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CAN/CSA-S6-06 A National Standard of Canada

Canadian Highway Bridge Design Code Reprinted October 2011. This reprint incorporates replacement pages issued as Supplement No.1 (May 2010) and Supplement No. 2 (October 2011) into the original 2006 Code.

CSA Standards Update Service CAN/CSA-S6-06 Reprinted October 2011 Title: Canadian Highway Bridge Design Code — originally published November 2006 Pagination: 889 pages (lxx preliminary and 819 text) Revisions issued: Supplement No. 1 — May 2010 Supplement No. 2 — October 2011

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National Standard of Canada

CAN/CSA-S6-06 Canadian Highway Bridge Design Code

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ISBN 1-55436-252-0 Technical Editor: Mark Braiter © Canadian Standards Association — 2006. Reprinted with revisions October 2011. All rights reserved. No part of this publication may be reproduced in any form whatsoever without the prior permission of the publisher.

© Canadian Standards Association

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Contents Technical Committee on the Canadian Highway Bridge Design Code (CAN/CSA-S6-06) xxxD Technical Committee on the Canadian Highway Bridge Design Code (CSA S6S1-10) xxxii Technical Committee on the Canadian Highway Bridge Design Code (CSA S6S2-11) xxxiv Subcommittee on Section 1 — General xxxivB Subcommittee on Section 2 — Durability xxxv Subcommittee on Section 3 — Loads (CAN/CSA-S6-06) xxxvi Subcommittee on Section 3 — Loads (CSA S6S1-10) xxxvii Subcommittee on Section 4 — Seismic design (CAN/CSA-S6-06) xxxviii Subcommittee on Section 4 — Seismic design (CSA S6S1-10) xxxix Subcommittee on Section 5 — Methods of analysis (CAN/CSA-S6-06) xl Subcommittee on Section 5 — Methods of analysis (CSA S6S1-10) xli Subcommittee on Section 6 — Foundations (CAN/CSA-S6-06) xlii Subcommittee on Section 6 — Foundations (CSA S6S1-10) xliii Subcommittee on Section 7 — Buried structures xliv Subcommittee on Section 8 — Concrete structures (CAN/CSA-S6-06) xlv Subcommittee on Section 8 — Concrete structures (CSA S6S1-10) xlvi Subcommittee on Section 9 — Wood structures xlvii Subcommittee on Section 10 — Steel structures (CAN/CSA-S6-06) xlviii Subcommittee on Section 10 — Steel structures (CSA S6S1-10) xlix Subcommittee on Section 11 — Joints and bearings l Subcommittee on Section 12 — Barriers and highway accessory supports li Subcommittee on Section 13 — Movable bridges lii Subcommittee on Section 14 — Evaluation (CAN/CSA-S6-06) liii Subcommittee on Section 14 — Evaluation (CSA S6S1-10) liv Subcommittee on Section 15 — Rehabilitation and repair lv Subcommittee on Section 16 — Fibre-reinforced structures (CAN/CSA-S6-06) lvi Subcommittee on Section 16 — Fibre-reinforced structures (CSA S6S1-10) lvii Code Calibration Task Force (CAN/CSA-S6-06) lix October 2011 (Replaces p. iii, May 2010)

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© Canadian Standards Association

Code Calibration Task Force (CSA S6S1-10) lx Editorial Task Force lxi French Translation Task Force (CAN/CSA-S6-06) lxii French Translation Task Force (CSA S6S1-10) lxiii Regulatory Authority Committee (CAN/CSA-S6-06) lxiv Regulatory Authority Committee (CSA S6S1-10) lxvi Regulatory Authority Committee (CSA S6S2-11) lxviA Preface lxvii Foreword lxx Section 1 — General 1 1.1 Scope 2 1.1.1 Scope of Code 2 1.1.2 Scope of this Section 2 1.1.3 Terminology 2 1.2 Reference publications 2 1.3 Definitions 10A 1.3.1 General 10A 1.3.2 General administrative definitions 10A 1.3.3 General technical definitions 10B 1.3.4 Hydraulic definitions 15 1.4 General requirements 16 1.4.1 Approval 16 1.4.2 Design 17 1.4.3 Evaluation and rehabilitation of existing bridges 18 1.4.4 Construction 18 1.5 Geometry 20 1.5.1 Planning 20 1.5.2 Structure geometry 20 1.6 Barriers 20 1.6.1 Superstructure barriers 20 1.6.2 Roadside substructure barriers 20 1.6.3 Structure protection in waterways 21 1.6.4 Structure protection at railways 21 1.7 Auxiliary components 21 1.7.1 Expansion joints and bearings 21 1.7.2 Approach slabs 21 1.7.3 Utilities on bridges 21 1.8 Durability and maintenance 22 1.8.1 Durability and protection 22 1.8.2 Bridge deck drainage 22 1.8.3 Maintenance 24 1.9 Hydraulic design 25 1.9.1 Design criteria 25 1.9.2 Investigations 26 1.9.3 Location and alignment 26 1.9.4 Estimation of scour 26

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October 2011 (Replaces p. iv, May 2010)

© Canadian Standards Association

1.9.5 1.9.6 1.9.7 1.9.8 1.9.9 1.9.10 1.9.11

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Protection against scour 27 Backwater 29 Soffit elevation 29 Approach grade elevation 30 Channel erosion control 30 Stream stabilization works and realignment 31 Culverts 31

Section 2 — Durability 33 2.1 Scope 34 2.2 Definitions 34 2.3 Design for durability 34 2.3.1 Design concept 34 2.3.2 Durability requirements 34 2.3.3 Structural materials 36 2.4 Aluminum 36 2.4.1 Deterioration mechanisms 36 2.4.2 Detailing for durability 36 2.5 Polychloroprene and polyisoprene 37 2.6 Polytetrafluoroethylene (PTFE) 37 2.7 Waterproofing membranes 37 2.8 Backfill material 37 2.9 Soil and rock anchors 37 2.10 Other materials 37 Section 3 — Loads 39 3.1 Scope 41 3.2 Definitions 41 3.3 Abbreviations and symbols 43 3.3.1 Abbreviations 43 3.3.2 Symbols 43 3.4 Limit states criteria 47 3.4.1 General 47 3.4.2 Ultimate limit states 47 3.4.3 Fatigue limit state 47 3.4.4 Serviceability limit states 47 3.5 Load factors and load combinations 48 3.5.1 General 48 3.5.2 Permanent loads 50 3.5.3 Transitory loads 51 3.5.4 Exceptional loads 51 3.6 Dead loads 51 3.7 Earth loads and secondary prestress loads 52 3.7.1 Earth loads 52 3.7.2 Secondary prestress effects 52 3.8 Live loads 52 3.8.1 General 52 3.8.2 Design lanes 52 3.8.3 CL-W loading 52 3.8.4 Application 54 3.8.5 Centrifugal force 56 3.8.6 Braking force 56 3.8.7 Curb load 56 3.8.8 Barrier loads 56 3.8.9 Pedestrian load 57 May 2010 (Replaces p. v, November 2006)

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3.8.10 3.8.11 3.8.12 3.9 3.9.1 3.9.2 3.9.3 3.9.4 3.10 3.10.1 3.10.2 3.10.3 3.10.4 3.10.5 3.11 3.11.1 3.11.2 3.11.3 3.11.4 3.11.5 3.11.6 3.11.7 3.12 3.12.1 3.12.2 3.12.3 3.12.4 3.12.5 3.12.6 3.13 3.14 3.14.1 3.14.2 3.14.3 3.14.4 3.14.5 3.14.6 3.14.7 3.15 3.16 3.16.1 3.16.2 3.16.3 3.16.4 3.16.5

© Canadian Standards Association

Maintenance access loads 57 Maintenance vehicle load 57 Multiple-use structures 57 Superimposed deformations 58 General 58 Movements and load effects 58 Superstructure types 58 Temperature effects 59 Wind loads 61 General 61 Design of the superstructure 62 Design of the substructure 63 Aeroelastic instability 64 Wind tunnel tests 65 Water loads 65 General 65 Static pressure 65 Buoyancy 65 Stream pressure 65 Wave action 66 Scour action 66 Debris torrents 66 Ice loads 67 General 67 Dynamic ice forces 67 Static ice forces 69 Ice jams 69 Ice adhesion forces 69 Ice accretion 69 Earthquake effects 69 Vessel collisions 70 General 70 Bridge classification 70 Assessment 70 Annual frequency of collapse 70 Design vessel 70 Application of collision forces 70 Protection of piers 71 Vehicle collision load 71 Construction loads and loads on temporary structures 71 General 71 Dead loads 71 Live loads 71 Segmental construction 71 Falsework 72

Annexes A3.1 (normative) A3.2 (normative) A3.3 (normative) A3.4 (normative)

— Climatic and environmental data 73 — Wind loads on highway accessory supports and slender structural elements 94 — Vessel collision 104 — CL-625-ONT live loading 113

Section 4 — Seismic design 115 4.1 Scope 117 4.2 Definitions 117

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May 2010 (Replaces p. vi, November 2006)

© Canadian Standards Association

4.3 4.3.1 4.3.2 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 4.4.6 4.4.7 4.4.8 4.4.9 4.4.10 4.5 4.5.1 4.5.2 4.5.3 4.6 4.6.1 4.6.2 4.6.3 4.6.4 4.6.5 4.6.6 4.7 4.7.1 4.7.2 4.7.3 4.7.4 4.7.5 4.8 4.8.1 4.8.2 4.8.3 4.8.4 4.8.5 4.9 4.9.1 4.9.2 4.10 4.10.1 4.10.2 4.10.3 4.10.4 4.10.5 4.10.6 4.10.7 4.10.8 4.10.9 4.10.10 4.10.11 4.10.12 4.10.13

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Abbreviation and symbols 119 Abbreviation 119 Symbols 119 Earthquake effects 122 General 122 Importance categories 122 Zonal acceleration ratio 123 Seismic performance zones 123 Analysis for earthquake loads 123 Site effects 125 Elastic seismic response coefficient 126 Response modification factors 127 Load factors and load combinations 128 Design forces and support lengths 128 Analysis 132 General 132 Single-span bridges 132 Multi-span bridges 133 Foundations 134 General 134 Liquefaction of foundation soils 134 Stability of slopes 135 Seismic forces on abutments and retaining walls 135 Soil-structure interaction 135 Fill settlement and approach slabs 135 Concrete structures 135 General 135 Seismic Performance Zone 1 135 Seismic Performance Zone 2 136 Seismic Performance Zones 3 and 4 136 Piles 138 Steel structures 140 General 140 Materials 140 Sway stability effects 140 Steel substructures 140 Other systems 144 Joints and bearings 144 General 144 Seismic design forces 144 Seismic base isolation 144 General 144 Zonal acceleration ratio 145 Seismic performance zones 145 Site effects and site coefficient 145 Response modification factors and design requirements for substructure 145 Analysis procedures 145 Clearance and design displacements for seismic and other loads 148 Design forces for Seismic Performance Zone 1 148 Design forces for Seismic Performance Zones 2, 3, and 4 148 Other requirements 148 Required tests of isolation system 149 Elastomeric bearings — Design 151 Elastomeric bearings — Construction 152

May 2010 (Replaces p. vii, November 2006)

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© Canadian Standards Association

4.10.14 4.10.15 4.11 4.11.1 4.11.2 4.11.3 4.11.4 4.11.5 4.11.6 4.11.7 4.11.8 4.11.9 4.11.10 4.11.11 4.11.12 4.11.13 4.11.14 4.11.15 4.12 4.12.1 4.12.2 4.12.3 4.12.4

Sliding bearings — Design 153 Sliding bearings — Construction 153 Seismic evaluation of existing bridges 153 General 153 Bridge classification 153 Damage levels 153 Performance criteria 153 Evaluation methods 153 Load factors and load combinations for seismic evaluation 154 Minimum support length 154 Member capacities 154 Required response modification factor 155 Response modification factor of existing substructure elements 155 Evaluation acceptance criteria 155 Other evaluation procedures 156 Bridge access 156 Liquefaction of foundation soils 156 Soil-structure interaction 156 Seismic rehabilitation 156 Performance criteria 156 Response modification factor for rehabilitation 156 Seismic rehabilitation 156 Seismic rehabilitation techniques 157

Section 5.1 5.2 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.4.8 5.4.9 5.4.10 5.4.11 5.4.12 5.4.13 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.5.6 5.5.7 5.5.8 5.6 5.6.1

5 — Methods of analysis 159 Scope 161 Definitions 161 Abbreviations and symbols 164 Abbreviations 164 Symbols 164 General requirements 167 Application 167 Analysis for limit states 167 Modelling 167 Structural responses 167 Factors affecting structural responses 170 Deformations 170 Diaphragms and bracing systems 170 Analysis of deck slabs 171 Analysis for redistribution of force effects 171 Analysis for accumulation of force effects due to construction sequence 171 Analysis for effects of prestress 171 Analysis for thermal effects 171 Secondary stability effects 171 Requirements for specific bridge types 171 General 171 Voided slab — Limitation on size of voids 171 Deck-on-girder 172 Truss and arch 172 Rigid frame and integral abutment types 172 Transverse wood deck 172 Box girder 172 Single-spine bridges 173 Dead load 173 Simplified methods of analysis (beam analogy method) 173

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May 2010 (Replaces p. viii, November 2006)

© Canadian Standards Association

5.6.2 5.7 5.7.1 5.7.2 5.8 5.8.1 5.8.2 5.8.3 5.9 5.9.1 5.9.2 5.9.3 5.10 5.10.1 5.10.2 5.10.3 5.11 5.11.1 5.11.2 5.11.3 5.11.4 5.11.5 5.12 5.12.1 5.12.2 5.12.3 5.12.4

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Refined methods of analysis 174 Live load 174 Simplified methods of analysis 174 Refined methods of analysis 202 Idealization of structure and interpretation of results 203 General 203 Effective flange widths for bending 203 Idealization for analysis 207 Refined methods of analysis for short- and medium-span bridges 207 Selection of methods of analysis 207 Specific applications 207 Model analysis 207 Long-span bridges 210 General 210 Cable-stayed bridges 210 Suspension bridges 210 Dynamic analysis 210 General requirements of structural analysis 210 Elastic dynamic responses 211 Inelastic-dynamic responses 211 Analysis for collision loads 211 Seismic analysis 211 Stability and magnification of force effects 212 General 212 Member stability analysis for magnification of member bending moments 212 Structural stability analysis for lateral sway 212 Structural stability analysis for assemblies of individual members 212A

Annexes A5.1 (normative) — Factors affecting structural response 213 A5.2 (informative) — Two-dimensional analysis 217 Section 6 — Foundations 225 6.1 Scope 227 6.2 Definitions 227 6.3 Abbreviations and symbols 229 6.3.1 Abbreviations 229 6.3.2 Symbols 229 6.4 Design requirements 230 6.4.1 Limit states 230 6.4.2 Effects on surroundings 231 6.4.3 Effects on structure 231 6.4.4 Components 231 6.4.5 Consultation 231 6.4.6 Inspection and quality control 231 6.5 Geotechnical investigation 231 6.5.1 General 231 6.5.2 Investigation procedures 232 6.5.3 Geotechnical parameters 232 6.5.4 Shallow foundations 232 6.5.5 Deep foundations 232 6.5.6 Report 232 6.6 Resistance and deformation 233 6.6.1 General 233 6.6.2 Ultimate limit state 233 May 2010 (Replaces p. ix, November 2006)

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6.6.3 6.7 6.7.1 6.7.2 6.7.3 6.7.4 6.7.5 6.8 6.8.1 6.8.2 6.8.3 6.8.4 6.8.5 6.8.6 6.8.7 6.8.8 6.8.9 6.8.10 6.9 6.9.1 6.9.2 6.9.3 6.9.4 6.9.5 6.9.6 6.10 6.10.1 6.10.2 6.10.3 6.10.4 6.11 6.11.1 6.11.2 6.11.3 6.11.4 6.12 6.12.1 6.12.2 6.12.3 6.13 6.13.1 6.13.2

© Canadian Standards Association

Serviceability limit state 234 Shallow foundations 235 General 235 Calculated geotechnical resistance at ULS 235 Pressure distribution 237 Effect of load inclination 238 Factored geotechnical horizontal resistance 239 Deep foundations 240 General 240 Selection of deep foundation units 240 Vertical load transfer 240 Downdrag 240 Factored geotechnical axial resistance 240 Group effects — Vertical loads 241 Factored geotechnical lateral resistance 241 Structural resistance 242 Embedment and spacing 242 Pile shoes and splices 243 Lateral and vertical pressures 243 General 243 Lateral pressures 243 Compaction surcharge 244 Effects of loads 245 Surcharge 245 Wheel load distribution through fill 245 Ground anchors 246 Application 246 Design 246 Materials and installation 246 Anchor testing 247 Sheet pile structures 247 Application 247 Design 247 Ties and anchors 248 Cellular sheet pile structures 248 MSE structures 248 Application 248 Design 248 Backfill 249 Pole foundations 249 Application 249 Design 249

Section 7 — Buried structures 251 7.1 Scope 252 7.2 Definitions 252 7.3 Abbreviation and symbols 254 7.3.1 Abbreviation 254 7.3.2 Symbols 254 7.4 Hydraulic design 258 Structural design 259 7.5 7.5.1 Limit states 259 7.5.2 Load factors 260 7.5.3 Material resistance factors 260 7.5.4 Geotechnical considerations 261

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May 2010 (Replaces p. x, November 2006)

© Canadian Standards Association

7.5.5 7.5.6 7.6 7.6.1 7.6.2 7.6.3 7.6.4 7.6.5 7.6.6 7.6.7 7.7 7.7.1 7.7.2 7.7.3 7.7.4 7.7.5 7.7.6 7.7.7 7.8 7.8.1 7.8.2 7.8.3 7.8.4 7.8.5 7.8.6 7.8.7 7.8.8 7.8.9 7.8.10 7.8.11 7.8.12 7.8.13 7.8.14 7.8.15

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Seismic requirements 262 Minimum clear spacing between conduits 262 Soil-metal structures 263 General 263 Structural materials 265 Design criteria 266 Additional design requirements 271 Construction 273 Special features 275 Site supervision and construction control 275 Metal box structures 276 General 276 Structural materials 276 Design criteria 277 Additional design considerations 278 Construction 278 Special features 279 Site supervision and construction control 279 Reinforced concrete buried structures 279 Standards for structural components 279 Standards for joint gaskets for precast concrete units 280 Installation criteria 280 Loads and load combinations 287 Earth pressure distribution from loads 288 Analysis 291 Ultimate limit state 291 Strength design 292 Serviceability limit state 295 Fatigue limit state 295 Minimum reinforcement 295 Distribution reinforcement 296 Details of the reinforcement 296 Joint shear for top slab of precast concrete box sections with depth of cover less than 0.6 m 297 Construction 297

Section 8 — Concrete structures 301 8.1 Scope 304 8.2 Definitions 304 8.3 Symbols 307 8.4 Materials 313 8.4.1 Concrete 313 8.4.2 Reinforcing bars and deformed wire 316 8.4.3 Tendons 316 8.4.4 Anchorages, mechanical connections, and ducts 317 8.4.5 Grout 318 8.4.6 Material resistance factors 318 8.5 Limit states 319 8.5.1 General 319 8.5.2 Serviceability limit states 319 8.5.3 Fatigue limit state 319 8.5.4 Ultimate limit states 320 8.6 Design considerations 320 8.6.1 General 320 8.6.2 Design 320 8.6.3 Buckling 323 May 2010 (Replaces p. xi, November 2006)

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8.7 8.7.1 8.7.2 8.7.3 8.7.4 8.8 8.8.1 8.8.2 8.8.3 8.8.4 8.8.5 8.8.6 8.8.7 8.9 8.9.1 8.9.2 8.9.3 8.9.4 8.9.5 8.10 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.11 8.11.1 8.11.2 8.11.3 8.12 8.12.1 8.12.2 8.12.3 8.12.4 8.12.5 8.12.6 8.13 8.13.1 8.13.2 8.13.3 8.14 8.14.1 8.14.2 8.14.3 8.14.4 8.14.5 8.14.6 8.15 8.15.1 8.15.2 8.15.3 8.15.4 8.15.5

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© Canadian Standards Association

Prestressing 323 Stress limitations for tendons 323 Concrete strength at transfer 324 Grouting 324 Loss of prestress 324 Flexure and axial loads 326 General 326 Assumptions for the serviceability and fatigue limit states 326 Assumptions for the ultimate limit states 327 Flexural components 327 Compression components 328 Tension components 331 Bearing 331 Shear and torsion 331 General 331 Design procedures 332 Sectional design model 333 Slabs, walls, and footings 337 Interface shear transfer 337 Strut-and-tie model 338 General 338 Structural idealization 338 Proportioning of a compressive strut 339 Proportioning of a tension tie 340 Proportioning of node regions 340 Crack control reinforcement 340 Durability 341 Deterioration mechanisms 341 Protective measures 341 Detailing for durability 346 Control of cracking 347 General 347 Distribution of reinforcement 347 Reinforcement 347 Crack control in the side faces of beams 348 Flanges of T-beams 348 Shrinkage and temperature reinforcement 348 Deformation 348 General 348 Dimensional changes 349 Deflections and rotations 349 Details of reinforcement and special detailing requirements 350 Hooks and bends 350 Spacing of reinforcement 351 Transverse reinforcement for flexural components 352 Transverse reinforcement for compression components 352 Reinforcement for shear and torsion 353 Maximum spacing of reinforcement for shear and torsion 353 Development and splices 353 Development 353 Development of reinforcing bars and deformed wire in tension 355 Development of reinforcing bars in compression 356 Development of pretensioning strand 357 Development of standard hooks in tension 357

May 2010 (Replaces p. xii, November 2006)

© Canadian Standards Association

8.15.6 8.15.7 8.15.8 8.15.9 8.16 8.16.1 8.16.2 8.16.3 8.16.4 8.16.5 8.16.6 8.16.7 8.17 8.18 8.18.1 8.18.2 8.18.3 8.18.4 8.18.5 8.18.6 8.18.7 8.19 8.19.1 8.19.2 8.19.3 8.19.4 8.20 8.20.1 8.20.2 8.20.3 8.20.4 8.20.5 8.20.6 8.20.7 8.21 8.22 8.22.1 8.22.2 8.22.3 8.22.4 8.22.5 8.22.6 8.22.7 8.23 8.23.1 8.23.2 8.23.3 8.23.4 8.23.5 8.23.6 8.23.7

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Combination development length 358 Development of welded wire fabric in tension 358 Mechanical anchorages 358 Splicing of reinforcement 358 Anchorage zone reinforcement 360 General 360 Post-tensioning anchorage zones 360 Pretensioning anchorage zones 363 Inclined anchorages 363 Intermediate anchorages 363 Anchorage blisters 363 Anchorage of attachments 363 Seismic design and detailing 366 Special provisions for deck slabs 367 Design methods 367 Minimum slab thickness 367 Allowance for wear 367 Empirical design method 367 Diaphragms 370 Edge stiffening 370 Distribution reinforcement 370 Composite construction 372 General 372 Flexure 372 Shear 372 Semi-continuous structures 372 Concrete girders 373 General 373 Effective flange width for T- and box girders 373 Flange thickness for T- and box girders 373 Isolated girders 373 Top and bottom flange reinforcement for cast-in-place T- and box girders 373 Post-tensioning tendons 374 Diaphragms 374 Multi-beam decks 374 Segmental construction 374 General 374 Additional ducts and anchorages 374 Diaphragms 375 Deviators for external tendons 375 Coupling of post-tensioning tendons 375 Special provisions for various bridge types 375 Precast segmental beam bridges 377 Concrete piles 378 General 378 Specified concrete strength 378 Handling 378 Splices 378 Pile dimensions 378 Non-prestressed concrete piles 378 Prestressed concrete piles 379

Section 9 — Wood structures 381 9.1 Scope 384 9.2 Definitions 384 May 2010 (Replaces p. xiii, November 2006)

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9.3 9.4 9.4.1 9.4.2 9.4.3 9.4.4 9.5 9.5.1 9.5.2 9.5.3 9.5.4 9.5.5 9.5.6 9.5.7 9.5.8 9.5.9 9.6 9.6.1 9.6.2 9.6.3 9.7 9.7.1 9.7.2 9.7.3 9.7.4 9.7.5 9.8 9.8.1 9.8.2 9.8.3 9.8.4 9.8.5 9.8.6 9.9 9.10 9.11 9.11.1 9.11.2 9.12 9.12.1 9.12.2 9.12.3 9.12.4 9.12.5 9.12.6 9.13 9.13.1 9.13.2 9.14 9.14.1 9.14.2 9.14.3 9.14.4 9.15

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Symbols 386 Limit states 388 General 388 Serviceability limit states 388 Ultimate limit states 388 Resistance factor 388 General design 389 Design assumption 389 Spans 389 Load-duration factor 389 Size-effect factors 389 Service condition 389 Load-sharing factor 389 Notched components 390 Butt joint stiffness factor 390 Treatment factor 391 Flexure 391 Flexural resistance 391 Size effect 391 Lateral stability 392 Shear 392 Shear resistance 392 Size effect 393 Shear force and shear load 393 Shear modulus 393 Vertically laminated decks 393 Compression members 393 General 393 Compressive resistance parallel to grain 394 Slenderness effect 394 Amplified moments 396 Rigorous evaluation of amplified moments 396 Approximate evaluation of amplified moments 398 Tension members 399 Compression at an angle to grain 400 Sawn wood 401 Materials 401 Specified strengths and moduli of elasticity 401 Glued-laminated timber 404 Materials 404 Specified strengths and moduli of elasticity 404 Vertically laminated beams 405 Camber 405 Varying depth 405 Curved members 406 Structural composite lumber 406 Materials 406 Specified strengths and moduli of elasticity 406 Wood piles 406 Materials 406 Splicing 406 Specified strengths and moduli of elasticity 406 Design 407 Fastenings 407

May 2010 (Replaces p. xiv, November 2006)

© Canadian Standards Association

9.15.1 9.15.2 9.15.3 9.16 9.17 9.17.1 9.17.2 9.17.3 9.17.4 9.17.5 9.17.6 9.17.7 9.17.8 9.17.9 9.17.10 9.17.11 9.17.12 9.18 9.18.1 9.18.2 9.18.3 9.18.4 9.19 9.19.1 9.19.2 9.19.3 9.19.4 9.19.5 9.20 9.20.1 9.20.2 9.21 9.21.1 9.21.2 9.21.3 9.22 9.22.1 9.22.2 9.22.3 9.22.4 9.22.5 9.23 9.23.1 9.23.2 9.23.3 9.23.4 9.23.5 9.23.6 9.23.7 9.23.8 9.24 9.25 9.25.1 9.25.2

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

General 407 Design 408 Construction 408 Hardware and metalwork 408 Durability 408 General 408 Pedestrian contact 408 Incising 408 Fabrication 409 Pressure preservative treatment of laminated veneer lumber 409 Pressure preservative treatment of parallel strand lumber 409 Field treatment 409 Treated round wood piles 409 Untreated round wood piles 409 Pile heads 409 Protective treatment of hardware and metalwork 409 Stress-laminated timber decking 410 Wood cribs 410 General 410 Member sizes and assembly 410 Fastening 410 Load transfer to cribs 410 Wood trestles 411 General 411 Pile bents 411 Framed bents 411 Caps 411 Bracing 411 Stringers and girders 411 Design details 411 Diaphragms 412 Nail-laminated wood decks 412 General 412 Transversely laminated wood decks 412 Longitudinal nail-laminated wood decks 413 Wood-concrete composite decks 413 General 413 Wood base 413 Concrete slab 414 Wood-concrete interface 415 Factored moment resistance 416 Stress-laminated wood decks 417 General 417 Post-tensioning materials 417 Design of post-tensioning system 417 Design of distribution bulkhead 419 Laminated decks 421 Net section 422 Hardware durability 422 Design details 423 Wearing course 423 Drainage 423 General 423 Deck 424

May 2010 (Replaces p. xv, November 2006)

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Section 10.1 10.2 10.3 10.3.1 10.3.2 10.4 10.4.1 10.4.2 10.4.3 10.4.4 10.4.5 10.4.6 10.4.7 10.4.8 10.4.9 10.4.10 10.4.11 10.4.12 10.4.13 10.5 10.5.1 10.5.2 10.5.3 10.5.4 10.5.5 10.5.6 10.5.7 10.5.8 10.5.9 10.6 10.6.1 10.6.2 10.6.3 10.6.4 10.6.5 10.6.6 10.6.7 10.7 10.7.1 10.7.2 10.7.3 10.7.4 10.7.5 10.8 10.8.1 10.8.2 10.8.3 10.8.4 10.9 10.9.1 10.9.2 10.9.3 10.9.4

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10 — Steel structures 425 Scope 428 Definitions 428 Abbreviations and symbols 430 Abbreviations 430 Symbols 430 Materials 437 General 437 Structural steel 437 Cast steel 437 Stainless steel 438 Bolts 438 Welding electrodes 438 Stud shear connectors 438 Cables 438 High-strength bars 438 Galvanizing and metallizing 438 Identification 438 Coefficient of thermal expansion 439 Pins and rollers 439 Design theory and assumptions 439 General 439 Ultimate limit states 439 Serviceability limit states 439 Fatigue limit state 439 Fracture control 440 Seismic requirements 440 Resistance factors 440 Analysis 440 Design lengths of members 440 Durability 441 General 441 Corrosion as a deterioration mechanism 441 Corrosion protection 441 Superstructure components 441 Other components 442 Areas inaccessible after erection 444 Detailing for durability 444 Design details 444 General 444 Minimum thickness of steel 444 Floor beams and diaphragms at piers and abutments 445 Camber 445 Welded attachments 446 Tension members 446 General 446 Axial tensile resistance 447 Axial tension and bending 447 Tensile resistance of cables 447 Compression members 447 General 447 Width-to-thickness ratio of elements in compression 448 Axial compressive resistance 450 Axial compression and bending 451

May 2010 (Replaces p. xvi, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

10.9.5 Composite columns 453 10.10 Beams and girders 455 10.10.1 General 455 10.10.2 Class 1 and 2 sections 455 10.10.3 Class 3 sections 457 10.10.4 Stiffened plate girders 457 10.10.5 Shear resistance 458 10.10.6 Intermediate transverse stiffeners 459 10.10.7 Longitudinal web stiffeners 460 10.10.8 Bearing stiffeners 461 10.10.9 Lateral bracing, cross-frames, and diaphragms 10.11 Composite beams and girders 463 10.11.1 General 463 10.11.2 Proportioning 463 10.11.3 Effects of creep and shrinkage 463 10.11.4 Control of permanent deflections 463 10.11.5 Class 1 and Class 2 sections 463 10.11.6 Class 3 sections 467 10.11.7 Stiffened plate girders 469 10.11.8 Shear connectors 470 10.11.9 Lateral bracing, cross-frames, and diaphragms 10.12 Composite box girders 472 10.12.1 General 472 10.12.2 Effective width of tension flanges 472 10.12.3 Web plates 472 10.12.4 Flange-to-web welds 472 10.12.5 Moment resistance 472 10.12.6 Diaphragms, cross-frames, and lateral bracing 10.12.7 Multiple box girders 475 10.12.8 Single box girders 475 10.13 Horizontally curved girders 476 10.13.1 General 476 10.13.2 Special considerations 476 10.13.3 Design theory 477 10.13.4 Bearings 477 10.13.5 Diaphragms, cross-frames, and lateral bracing 10.13.6 Steel I-girders 478 10.13.7 Composite box girders 480 10.13.8 Camber 482 10.14 Trusses 482 10.14.1 General 482 10.14.2 Built-up members 482 10.14.3 Bracing 483 10.15 Arches 484 10.15.1 General 484 10.15.2 Width-to-thickness ratios 484 10.15.3 Longitudinal web stiffeners 484 10.15.4 Axial compression and bending 484 10.15.5 Arch ties 485 10.16 Orthotropic decks 485 10.16.1 General 485 10.16.2 Effective width of deck 485 10.16.3 Superposition of local and global effects 485 10.16.4 Deflection 486

May 2010 (Replaces p. xvii, November 2006)

462

472

474

477

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10.16.5 10.16.6 10.16.7 10.17 10.17.1 10.17.2 10.17.3 10.17.4 10.18 10.18.1 10.18.2 10.18.3 10.18.4 10.18.5 10.19 10.19.1 10.19.2 10.20 10.20.1 10.20.2 10.21 10.21.1 10.21.2 10.21.3 10.22 10.22.1 10.22.2 10.22.3 10.22.4 10.22.5 10.22.6 10.22.7 10.22.8 10.23 10.23.1 10.23.2 10.23.3 10.23.4 10.23.5 10.23.6 10.24 10.24.1 10.24.2 10.24.3 10.24.4 10.24.5 10.24.6 10.24.7 10.24.8 10.24.9 10.24.10

© Canadian Standards Association

Girder diaphragms 486 Design detail requirements 486 Wearing surface 487 Structural fatigue 488 General 488 Live-load-induced fatigue 488 Distortion-induced fatigue 500 Orthotropic decks 501 Splices and connections 501 General 501 Bolted connections 502 Welds 504 Detailing of bolted connections 505 Connection reinforcement and stiffening 508 Anchor rods 509 General 509 Anchor rod resistance 509 Pins, rollers, and rockers 510 Bearing resistance 510 Pins 510 Torsion 511 General 511 Members of closed cross-section 511 Members of open cross-section 512 Steel piles 513 General 513 Resistance factors 513 Compressive resistance 513 Unsupported length 513 Effective length factor 513 Splices 513 Welding 513 Composite tube piles 513 Fracture control 514 General 514 Identification 514 Fracture toughness 514 Welding of fracture-critical and primary tension members 515 Welding corrections and repairs to fracture-critical members 516 Non-destructive testing of fracture-critical members 519 Construction requirements for structural steel 519 General 519 Submissions 519 Materials 520 Fabrication 520 Welded construction 523 Bolted construction 524 Tolerances 527 Quality control 528 Transportation and delivery 529 Erection 529

Section 11 — Joints and bearings 531 11.1 Scope 532 11.2 Definitions 532

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© Canadian Standards Association

11.3 11.3.1 11.3.2 11.4 11.4.1 11.4.2 11.5 11.5.1 11.5.2 11.5.3 11.5.4 11.5.5 11.5.6 11.5.7 11.5.8 11.5.9 11.6 11.6.1 11.6.2 11.6.3 11.6.4 11.6.5 11.6.6 11.6.7 11.6.8 11.6.9 11.6.10 Section 12.1 12.2 12.3 12.3.1 12.3.2 12.4 12.4.1 12.4.2 12.4.3 12.4.4 12.4.5 12.4.6 12.5 12.5.1 12.5.2 12.5.3 12.5.4 12.5.5 12.5.6 12.5.7 12.5.8 12.5.9 12.5.10 12.5.11

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Abbreviations and symbols 533 Abbreviations 533 Symbols 534 Common requirements 534 General 534 Design requirements 535 Deck joints 535 General requirements 535 Selection 536 Design 537 Fabrication 537 Installation 538 Joint seals 538 Sealed joint drainage 538 Open joint drainage 538 Volume control joint 538 Bridge bearings 538 General 538 Metal back, roller, and spherical bearings 539 Sliding surfaces 540 Spherical bearings 543 Pot bearings 544 Elastomeric bearings 545 Disc bearings 548 Guides for lateral restraints 549 Other bearing systems 550 Load plates and attachment for bearings 550 12 — Barriers and highway accessory supports 551 Scope 552 Definitions 552 Abbreviations and symbols 553 Abbreviations 553 Symbols 553 Barriers 554 General 554 Barrier joints 554 Traffic barriers 554 Pedestrian barriers 562 Bicycle barriers 563 Combination barriers 564 Highway accessory supports 564 General 564 Vertical clearances 564 Maintenance 564 Aesthetics 564 Design 564 Breakaway supports 566 Foundations 566 Corrosion protection 567 Minimum thicknesses 567 Camber 567 Connections 567

May 2010 (Replaces p. xix, November 2006)

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Section 13.1 13.2 13.3 13.4 13.4.1 13.4.2 13.4.3 13.4.4 13.4.5 13.4.6 13.4.7 13.4.8 13.4.9 13.4.10 13.5 13.5.1 13.5.2 13.5.3 13.5.4 13.5.5 13.5.6 13.5.7 13.5.8 13.5.9 13.5.10 13.5.11 13.5.12 13.5.13 13.6 13.6.1 13.6.2 13.6.3 13.6.4 13.6.5 13.7 13.7.1 13.7.2 13.7.3 13.7.4 13.7.5 13.7.6 13.7.7 13.7.8 13.7.9 13.7.10 13.7.11 13.7.12 13.7.13 13.7.14 13.7.15 13.7.16 13.7.17 13.7.18

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© Canadian Standards Association

13 — Movable bridges 569 Scope 572 Definitions 572 Symbols 572 Materials 573 General 573 Structural steel 573 Concrete 573 Timber 574 Carbon steel 574 Forged steel 574 Cast steel or iron 574 Bronze 574 Bolts 574 Wire rope 574 General design requirements 574 General 574 Type of deck 574 Piers and abutments 574 Navigation requirements 574 Vessel collision 574 Protection of traffic 575 Fire protection 575 Time of operation 575 Aligning and locking 575 Houses for machinery, electrical equipment, and operators 575 New devices 575 Access for routine maintenance 575 Durability 576 Movable bridge components 576 General features 576 Swing bridge components 580 Bascule bridge components 583 Rolling lift bridge components 583 Vertical lift bridge components 584 Structural analysis and design 589 General 589 Design theory and assumptions 589 Wind loads 589 Seismic loads 590 Reaction due to temperature differential 590 Hydraulic cylinder connections 591 Loads on end floor beams and stringer brackets 591 Swing bridges — Ultimate limit states 591 Bascule (including rolling lift) bridges — Ultimate limit states 592 Vertical lift bridges — Ultimate limit states 593 Dead load factor 593 All movable bridges — Ultimate limit states 594 Special types of movable bridges 594 Load effects 594 Fatigue limit state 594 Friction 594 Machinery supports 594 Vertical lift bridge towers 594

May 2010 (Replaces p. xx, November 2006)

© Canadian Standards Association

13.7.19 13.8 13.8.1 13.8.2 13.8.3 13.8.4 13.8.5 13.8.6 13.8.7 13.8.8 13.8.9 13.8.10 13.8.11 13.8.12 13.8.13 13.8.14 13.8.15 13.8.16 13.8.17 13.8.18 13.8.19 13.8.20 13.9 13.10 13.10.1 13.10.2 13.10.3 13.10.4 13.10.5 13.10.6 13.10.7 13.10.8 13.10.9 13.10.10 13.10.11 13.10.12 13.10.13 13.10.14 13.10.15 13.10.16 13.10.17 13.10.18 13.10.19 13.10.20 13.10.21 13.10.22 13.10.23 13.10.24 13.10.25 13.10.26 13.10.27 13.10.28 13.10.29 13.10.30

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Transitory loads 594 Mechanical system design 594 General 594 Operating machinery 595 Power sources 595 Prime mover 595 Power requirements for main machinery 596 Wedges 596 Brakes 597 Frictional resistance 598 Torque 599 Application of worker power 601 Machinery loads 601 Allowable stresses for machinery and allowable hydraulic pressures 601 Bearing pressures (moving surfaces) 603 Line-bearing pressure 605 Design of wire ropes 605 Shafting 607 Machinery fabrication and installation 608 Lubrication 614 Power equipment 615 Quality of work 617 Hydraulic system design 618 Electrical system design 619 General 619 Canadian Electrical Code, Part I 619 General requirements for electrical installation 619 Working drawings 620 Motor and generator tests 620 Motors — General requirements 621 Motor torque for span operation 621 Motor temperature, insulation, and service factor 622 Number of motors 622 Synchronizing motors for tower-drive vertical lift bridges 622 Speed of motors 622 Gear motors 622 Engine-generator sets 622 Automatic electric power transfer 623 Electrically operated motor brakes 624 Electrically operated machinery brakes 625 Design of electrical parts 625 Electrical control 625 Speed control for span-driving motors 627 Master switches and relays for span-driving motors 628 Programmable logic controllers 628 Resistances and reactors 628 Limit switches 629 Interlocking 629 Switches 629 Circuit breakers and fuses 630 Contact areas 630 Magnetic contactors 630 Overload relays 630 Shunt coils 630

May 2010 (Replaces p. xxi, November 2006)

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13.10.31 13.10.32 13.10.33 13.10.34 13.10.35 13.10.36 13.10.37 13.10.38 13.10.39 13.10.40 13.10.41 13.10.42 13.10.43 13.10.44 13.10.45 13.10.46 13.10.47 13.10.48 13.10.49 13.10.50 13.11 13.11.1 13.11.2 13.11.3 13.12 13.13 13.14

© Canadian Standards Association

Instruments 630 Protection of electrical equipment 631 Cast iron in electrical parts 631 Position indicators and meters 631 Indicating lights 631 Control console 631 Control panels 632 Enclosures for panel boards 632 Electrical wires and cables 632 Tagging of wires 633 Wire splices and connections 633 Raceways, metal conduits, conduit fittings, and boxes 633 Electrical connections between fixed and moving parts 634 Electrical connections across the navigable channel 635 Service lights 635 Navigation lights 636 Aircraft warning lights 636 Circuits 636 Grounding and lightning protection 636 Spare parts 636 Construction 637 Shop assemblies 637 Coating 637 Erection 637 Training and start-up assistance 639 Operating and maintenance manual 639 Inspection 640

Section 14 — Evaluation 641 14.1 Scope 643 14.2 Definitions 643 14.3 Symbols 643 14.4 General requirements 646 14.4.1 Exclusions 646 14.4.2 Expertise 646 14.4.3 Future growth of traffic or future deterioration 647 14.4.4 Scope of evaluation 647 14.5 Evaluation procedures 647 14.5.1 General 647 14.5.2 Limit states 647 14.5.3 Deleted 14.5.4 Evaluation methodology 648 14.5.5 Bridge posting 648 14.6 Condition inspection 648 14.6.1 General 648 14.6.2 Plans 649 14.6.3 Physical features 649 14.6.4 Deterioration 649 14.7 Material strengths 649 General 649 14.7.1 14.7.2 Review of original construction documents 649 14.7.3 Analysis of tests of samples 649 14.7.4 Strengths based on date of construction 650 14.7.5 Deteriorated material 651 14.8 Permanent loads 651

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May 2010 (Replaces p. xxii, November 2006)

© Canadian Standards Association

14.8.1 14.8.2 14.8.3 14.8.4 14.8.5 14.9 14.9.1 14.9.2 14.9.3 14.9.4 14.9.5 14.10 14.11 14.11.1 14.11.2 14.11.3 14.11.4 14.12 14.12.1 14.12.2 14.12.3 14.12.4 14.12.5 14.13 14.13.1 14.13.2 14.13.3 14.14 14.14.1 14.14.2 14.14.3 14.15 14.15.1 14.15.2 14.15.3 14.15.4 14.16 14.16.1 14.16.2 14.16.3 14.16.4 14.17 14.17.1 14.17.2 14.17.3 14.18

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

General 651 Dead load 651 Earth pressure and hydrostatic pressure 652 Shrinkage, creep, differential settlement, and bearing friction 652 Secondary effects from prestressing 652 Transitory loads 652 Normal traffic 652 Permit — Vehicle loads 656 Dynamic load allowance for permit vehicle loads and alternative loading 657 Multiple-lane loading 657 Loads other than traffic 658 Exceptional loads 659 Lateral distribution categories for live load 659 General 659 Statically determinate method 659 Sophisticated method 659 Simplified method 659 Target reliability index 659 General 659 System behaviour 660 Element behaviour 660 Inspection level 660 Important structures 660 Load factors 661 General 661 Permanent loads 662 Transitory loads 662 Resistance 665 General 665 Resistance adjustment factor 672 Effects of defects and deterioration 673 Live load capacity factor 674 General 674 Ultimate limit states 674 Serviceability limit states 675 Combined load effects 675 Load testing 675 General 675 Instrumentation 676 Test load 676 Application of load test results 676 Bridge posting 677 General 677 Calculation of posting loads 677 Posting signs 678 Fatigue 679

Annexes A14.1 (normative) — Equivalent material strengths from tests of samples 680 A14.2 (normative) — Evaluation Level 1 (vehicle trains) in Ontario 682 A14.3 (normative) — Evaluation Level 2 (two-unit vehicles) in Ontario 683 A14.4 (normative) — Evaluation Level 3 (single-unit vehicles) in Ontario 684

May 2010 (Replaces p. xxiii, November 2006)

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S6S1-10

Section 15 — Rehabilitation and repair 15.1 Scope 688 15.2 Symbols 688 15.3 General requirements 688 15.3.1 Limit states 688 15.3.2 Condition data 688 15.3.3 Rehabilitation loads and load factors 15.3.4 Analysis 688 15.3.5 Factored resistances 688 15.3.6 Fatigue 688 15.3.7 Bridge posting 689 15.3.8 Seismic upgrading 689 15.4 Special considerations 689 15.5 Data collection 689 15.6 Rehabilitation loads and load factors 15.6.1 Loads 689 15.6.2 Load factors and load combinations 15.7 Analysis 692 15.8 Resistance 692 15.8.1 Existing members 692 15.8.2 New members 692

© Canadian Standards Association

687

688

689 691

Section 16 — Fibre-reinforced structures 693 16.1 Scope 695 16.1.1 Components 695 16.1.2 Fibres 695 16.1.3 Matrices 695 16.1.4 Uses requiring Approval 695 16.2 Definitions 695 16.3 Abbreviations and symbols 697 16.3.1 Abbreviations 697 16.3.2 Symbols 698 16.4 Durability 701 16.4.1 FRP tendons, primary reinforcement, and strengthening systems 701 16.4.2 FRP secondary reinforcement 701 16.4.3 Fibres in FRC 701 16.4.4 Cover to reinforcement 702 16.4.5 Protective measures 702 16.4.6 Allowance for wear in deck slabs 702 16.4.7 Detailing of concrete components for durability 702 16.4.8 Handling, storage, and installation of fibre tendons and primary reinforcement 702 16.5 Fibre-reinforced polymers 702 16.5.1 Material properties 702 16.5.2 Confirmation of the specified tensile strength 702 16.5.3 Resistance factor 703 16.6 Fibre-reinforced concrete 703 16.6.1 General 703 16.6.2 Fibre volume fraction 703 16.6.3 Fibre dispersion in concrete 704 16.7 Externally restrained deck slabs 704 16.7.1 General 704 16.7.2 Full-depth cast-in-place deck slabs 705 16.7.3 Cast-in-place deck slabs on stay-in-place formwork 706 16.7.4 Full-depth precast concrete deck slabs 706 16.8 Concrete beams and slabs 711

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May 2010 (Replaces p. xxiv, November 2006)

© Canadian Standards Association

16.8.1 16.8.2 16.8.3 16.8.4 16.8.5 16.8.6 16.8.7 16.8.8 16.9 16.9.1 16.9.2 16.9.3 16.9.4 16.9.5 16.9.6 16.10 16.11 16.11.1 16.11.2 16.11.3 16.12 16.12.1 16.12.2 16.12.3

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

General 711 Deformability and minimum reinforcement 711 Non-prestressed reinforcement 712 Development length for FRP bars and tendons 712 Development length for FRP grids 712 Tendons 712 Design for shear 713 Internally restrained cast-in-place deck slabs 714 Stressed wood decks 715 General 715 Post-tensioning materials 715 Post-tensioning system 715 Stressing procedure 716 Design of bulkheads 716 Stressed log bridges 716 Barrier walls 718 Rehabilitation of existing concrete structures with FRP 719 General 719 Flexural and axial load rehabilitation 720 Shear rehabilitation with externally bonded FRP systems 722 Rehabilitation of timber bridges 724 General 724 Strengthening for flexure 725 Strengthening for shear 726

Annexes A16.1 (normative — Installation of FRP strengthening systems 729 A16.2 (normative) — Quality control for FRP strengthening systems 732 Section 17 — Aluminum Structures 735 17.1 Scope 738 17.2 Definitions 738 17.3 Abbreviations and symbols 740 17.3.1 Abbreviations 740 17.3.2 Symbols 740 17.4 Materials 745 17.4.1 General 745 17.4.2 Mechanical strengths 746 17.4.3 Physical properties 747 17.4.4 Bolts 747 17.4.5 Welding electrodes 747 17.4.6 Identification 747 17.5 Design theory and assumptions 748 17.5.1 General 748 17.5.2 Ultimate limit states (ULS) 748 17.5.3 Serviceability limit states (SLS) 748 17.5.4 Fatigue limit state 748 17.5.5 Fracture control 748 17.5.6 Seismic requirements 748 17.5.7 Resistance factors 748 17.5.8 Analysis 748 17.5.9 Design lengths of members 749 17.6 Durability 749 17.6.1 Corrosion protection 749

October 2011 (Replaces p. xxv, May 2010)

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S6S2-11

17.6.2 17.7 17.7.1 17.7.2 17.7.3 17.7.4 17.8 17.8.1 17.8.2 17.8.3 17.8.4 17.9 17.9.1 17.9.2 17.10 17.10.1 17.10.2 17.10.3 17.10.4 17.11 17.11.1 17.11.2 17.11.3 17.12 17.12.1 17.12.2 17.12.3 17.12.4 17.13 17.13.1 17.13.2 17.13.3 17.13.4 17.14 17.14.1 17.14.2 17.15 17.15.1 17.15.2 17.15.3 17.15.4 17.16 17.16.1 17.16.2 17.16.3 17.16.4 17.16.5 17.16.6 17.16.7 17.17 17.17.1 17.17.2

xxvi

© Canadian Standards Association

Detailing for durability 749 Design details 750 General 750 Minimum nominal thickness 750 Camber 750 Welded attachments 750 Cross-sectional areas, effective section, and effective strength 751 General 751 Cross-sectional areas 751 Effective section 751 Effective strength and overall buckling 752 Local buckling 753 Flat elements 753 Curved elements 757 Tension members 758 Limiting slenderness for tension members 758 Shear lag effect 758 Axial tensile resistance 760 Pin-connected tension members 760 Compression members 760 Limiting slenderness for compression members 760 Buckling 760 Members in axial compression 762 Flexural members 765 Classification of members in bending 765 Moment resistance of members not subject to lateral torsional buckling 765 Moment resistance of members subject to lateral torsional buckling 766 Webs in shear — Flat elements 768 Members in torsion 771 General 771 Hollow sections 771 Members of solid compact cross-section 772 Members of open cross-section 772 Members with combined axial force and bending moment 772 Axial tension and bending 772 Axial compression and bending 773 Built-up compression members 775 Spacing of connectors 775 Multiple-bar members with discrete shear connectors 775 Double angle struts 776 Lattice columns and beam-columns 776 Composite beams and girders 777 General 777 Concrete slab 777 Proportioning 778 Effects of creep and shrinkage 778 Control of permanent deflections 778 Resistance of composite section 778 Shear connectors 781 Trusses 782 General 782 Built-up members 782

October 2011 (Replaces p. xxvi, May 2010)

© Canadian Standards Association

17.17.3 17.18 17.18.1 17.18.2 17.18.3 17.18.4 17.18.5 17.19 17.19.1 17.19.2 17.19.3 17.19.4 17.19.5 17.19.6 17.19.7 17.19.8 17.19.9 17.20 17.20.1 17.20.2 17.20.3 17.20.4 17.21 17.21.1 17.21.2 17.22 17.22.1 17.22.2 17.22.3 17.22.4 17.23 17.24 17.24.1 17.24.2 17.25 17.25.1 17.25.2 17.25.3 17.25.4 17.25.5 17.25.6 17.25.7 17.25.8 17.25.9

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Bracing 782 Arches 783 General 783 Width-to-thickness ratios 783 Longitudinal web stiffeners 783 Axial compression and bending 784 Arch ties 784 Decks 784 General 784 Effective width of deck 784 Superposition of local and global effects 784 Longitudinal flexure 784 Transverse flexure 784 Decks in longitudinal compression 784 In-plane moment in decks 785 In-plane shear in decks 786 Wearing surface 786 Structural fatigue 787 General 787 Live-load-induced fatigue 787 Distortion-induced fatigue 790 Bridge decks 798 Fracture control 798 General 798 Identification 798 Splices and connections 798 General 798 Bolted connections 799 Welded connections 803 Gusset plate connections 809 Anchors 809 Pins, rollers, and rockers 809 Bearing resistance 809 Pins 810 Construction requirements 810 Submissions 810 Materials 811 Fabrication 811 Welded construction 813 Bolted construction 814 Tolerances 816 Quality control 817 Transportation and delivery 818 Erection 818

October 2011 (Replaces p. xxvii, May 2010)

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Tables 1.1 — 3.1 — 3.2 — 3.3 — 3.4 — 3.5 — 3.6 — 3.7 — 3.8 — 3.9 — 3.10 — 3.11 — 4.1 — 4.2 — 4.3 — 4.4 — 4.5 — 4.6 — 4.7 — 4.8 — 4.9 — 5.1 — 5.2 — 5.3 —

© Canadian Standards Association

7.11 — 7.12 — 7.13 —

Highway classes 17 Load factors and load combinations 49 Permanent loads — Maximum and minimum values of load factors for ULS 50 Unit material weights 51 Number of design lanes 52 Modification factor for multi-lane loading 55 Loads on traffic barriers 57 Maximum and minimum effective temperatures 59 Wind exposure coefficient, Ce 62 Modification of wind loads on superstructure with skew angle 64 Longitudinal drag coefficient, CD 66 Lateral load coefficient, CL 66 Seismic performance zones 123 Minimum analysis requirements for multi-span bridges 124 Regular bridge requirements 125 Site coefficient, S 125 Response modification factor, R 127 Modification factor, K 131 Site coefficient for seismic isolation design, Si 145 Damping coefficient, B 147 Minimum analysis requirements for evaluation 154 Structural responses 168 Superstructure categories for simplified methods of analysis for live load 175 F and Cf for longitudinal bending moments in shallow superstructures corresponding to ultimate and serviceability limit states 177 F and Cf for longitudinal bending moments in shallow superstructures corresponding to the fatigue limit state 185 Ce for longitudinal bending moments in shallow superstructures corresponding to the fatigue and vibration limit state 187 F and Cf for longitudinal moments in multi-spine bridges 189 F for longitudinal vertical shear corresponding to ultimate and serviceability limit states, m 191 F for longitudinal vertical shear corresponding to fatigue limit state, m 192 F for longitudinal vertical shear in multi-spine bridges 193 Maximum cantilever moments, My , due to unfactored CL-625 Truck wheel loads (DLA included), kN•m/m 196 Effective deck plate width for a longitudinal rib 205 Selection of methods of analysis 208 Geotechnical resistance factors 234 Equivalent fluid pressure per metre width, kPa/m 244 Requirements for cut ends 258 Specific limit states 260 Material resistance factors 261 Soil classifications 265 Secant modulus of soil, Es , for various soils 266 Values for k4 for calculating equivalent line loads 270 Minimum transverse distance of backfill in single-conduit soil-metal structures 275 Standards for precast buried concrete structures 280 Classification of placed soils 280 Soils and compaction requirements for standard installations for circular precast concrete pipes 283 Soils and compaction requirements for standard installations for concrete boxes 284 Vertical and horizontal arching factors for circular concrete pipes in standard installations 287 Vertical and horizontal arching factors for box sections in standard installations 288

xxviii

October 2011 (Replaces p. xxxviii, May 2010)

5.4

—

5.5

—

5.6 5.7 5.8 5.9 5.10

— — — — —

5.11 5.12 6.1 6.2 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10

— — — — — — — — — — — — — —

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

— Force factors for earth loads 289 — Earth pressure factors 289 — Length factors for earth pressures 290 — Crack-control coefficient, C1 295 — Shrinkage and temperature reinforcement 296 — Material resistance factors 319 — Prestressing tendon stress limits 324 — Friction factors 325 — Maximum water to cementing materials ratio 341 — Minimum concrete covers and tolerances 344 — Maximum crack width 347 — Minimum bend diameter, mm 350 — Minimum development length of reinforcing bars and deformed wire in tension 355 — Modification factors for development length 356 — Modification factors for hook development length 357 — Classification of lap splices in tension 359 — Construction tolerances 377 — Resistance factor for wood components,  389 — Load-sharing factor for bending, shear, and tension for all species and grades 390 — Values of De 390 — Size-effect factors ksb for flexure and ksv for shear for all species and grades 392 — Modification factor for lateral stability, ks 392 — Minimum values of the effective length factor, k 395 — A, S, and eo for piles at 0.55 of the effective length below the butt joint 397 —  to be used in calculating Pcr for piles 399 — Size-effect factor, kst , for tension at net section in dimension lumber 400 — Size-effect factor for bearing, ksq 400 — Permitted species and species combinations for sawn wood 401 — Specified strengths and moduli of elasticity for structural joists and planks, MPa 402 — Specified strengths and moduli of elasticity for beam and stringer grades, MPa 403 — Specified strengths and moduli of elasticity for post and timber grades, MPa 404 — Specified strengths and moduli of elasticity for glued-laminated Douglas fir timber, MPa 405 — Typical specified strengths and moduli of elasticity for structural composite lumber, MPa 406 — Specified strengths and moduli of elasticity for round wood piles, MPa 407 — Limiting pressure perpendicular to grain, fq , MPa 419 — Minimum section properties for steel channel bulkheads 420 — Corrosion protection for superstructure components 442 — Corrosion protection for other components 443 — Width-to-thickness ratio of elements in compression 449 — Fatigue life constants and constant amplitude threshold stress ranges 489 — Values of Nd 490 — Average daily truck traffic 490 — Detail categories for load-induced fatigue 491 — Detail categories for load-induced fatigue of orthotropic decks 498 — Values of ks and c1 503 — Matching electrode classifications for CSA G40.21 and CSA W59 steels 504 — Minimum edge distance for bolt holes 507 — Impact test temperatures and Charpy impact energy requirements for fracture-critical members 514A 10.13 — Impact test temperatures and Charpy impact energy requirements for primary tension members 514A 10.14 — Deleted 10.14A — Impact test temperatures and Charpy impact energy requirements for weld metal in fracture-critical members 515

7.14 7.15 7.16 7.17 7.18 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12 9.13 9.14 9.15 9.16 9.17 9.18 9.19 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12

October 2011 (Replaces p. xxix, May 2010)

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S6S2-11

© Canadian Standards Association

10.14B — Impact test temperatures and Charpy impact energy requirements for weld metal in primary tension members 515 10.15 — Preheat and interpass temperature for steel grades 518 10.16 — Minimum elapsed time for acceptance testing 519 10.17 — Minimum bend radii for bent plates 521 10.18 — Nut rotation from snug-tight condition 525 10.19 — Facing of bearing surfaces roughness requirements 527 11.1 — Dimensions for confined sheet PTFE 541 11.2 — Dimensions for stainless steel 541 11.3 — Maximum average contact pressure for PTFE, MPa 542 11.4 — Design coefficient of friction 543 11.5 — Physical properties of polyisoprene and polychloroprene 546 12.1 — Highway type factors, Kh 555 12.2 — Highway curvature factors, Kc 555 12.3 — Highway grade factors, Kg 556 12.4 — Superstructure height factors, Ks 556 12.5 — Optimum performance levels — Barrier clearance less than or equal to 2.25 m 557 12.6 — Optimum performance levels — Barrier clearance greater than 2.25 m and less than or equal to 3.75 m 558 12.7 — Optimum performance levels — Barrier clearance greater than 3.75 m 559 12.8 — Minimum barrier heights, H 560 12.9 — Strengths for aluminum castings 565 13.1 — Maximum tensile strength for Grade 1770 bright wire 586 13.2 — Maximum tensile strength for Grade 110/120 bright wire 586 13.3 — Swing bridges — Special load combinations and load factors 591 13.4 — Bascule (including rolling lift) bridges — Special load combinations and load factors 592 13.5 — Vertical lift bridges — Special load combinations and load factors 593 13.6 — Dead load factor,  D 593 13.7 — Coefficients of friction 598 13.8 — Machinery losses and efficiency coefficients 599 13.9 — Coefficients of friction for sliding span locks and end and centre wedges 599 13.10 — Maximum allowable stresses in trunnions, MPa (psi) 602 13.11 — Maximum allowable stresses for machinery parts other than trunnions, MPa (psi) 602 13.12 — Maximum bearing pressures 604 13.13 — Ultimate stress and ultimate strength of steel wire rope of 6 × 19 classification and 6 × 25 filler construction 606 13.14 — Permissible stresses in gear teeth 612 13.15 — Fits and finishes 618 14.1 — Properties of structural steel 650 14.2 — Minimum yield strengths of reinforcing steel, MPa 651 14.3 — Modification factors for multiple-lane loading 658 14.4 — Fraction of CL1-W loading to be applied in the other lanes 658 14.5 — Target reliability index, , for normal traffic and for PA, PB, and PS traffic 661 14.6 — Target reliability index, , for PC traffic 661 14.7 — Maximum dead load factors,  D 662 14.8 — Live load factors, L , for normal traffic (Evaluation Levels 1, 2, and 3) for all types of analysis 662 14.9 — Live load factors, L , for normal traffic (alternative loading) for all types of analysis 663 14.10 — Live load factors, L , for PA traffic 663 14.11 — Live load factors, L , for PB traffic 664 14.12 — Live load factors, L , for PC traffic 664 14.13 — Live load factors, L , for PS traffic 664 14.14 — Specified strengths and moduli of elasticity for beam and stringer grades and post and timber grades, MPa 672

xxx

October 2011 (Replaces p. xxx, May 2010)

© Canadian Standards Association

14.15 15.1 16.1 16.2 16.3 16.4

— — — — — —

16.5 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 17.10 17.11 17.12

— — — — — — — — — — — — —

Figures 3.1 — 3.2 — 3.3 — 3.4 — 3.5 — 3.6 — 3.7 — 4.1 — 5.1 — 5.1A — 5.2 — 5.3 — 5.4 — 5.5 — 5.6 — 6.1 — 6.2 — 6.3 — 6.4 — 6.5 — 6.6 — 7.1 — 7.2 — 7.3 — 7.4 — 7.5 — 7.6 — 7.7 — 7.8 — 7.9 — 7.10 —

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Resistance adjustment factor, U 673 Rehabilitation design live loads for restricted normal traffic 690 Conditions of use for FRP tendons and primary reinforcement 701 FRP for pultruded FRP and aramid fibre rope 703 Minimum values of Ri for various applications 704 Maximum permissible stresses in FRP tendons at jacking and transfer for concrete beams and slabs for pretensioning and post-tensioning systems 713 Values of KbFRP 725 Radiographic inspection frequency requirements for castings 746 Mechanical strengths 746 Mechanical strengths for common wrought products 747 Effective length factor, K 763 Fatigue life constants and constant amplitude threshold stress ranges 789 Values of Nd 789 Average daily truck traffic 789 Detail categories for load-induced fatigue 791 Aluminum alloy filler metals for structural welding of various base aluminum alloys 804 Recommended minimum bend radii for 90° cold bends of sheet and plate 813 Nut rotation from snug-tight condition* 814 Facing of bearing surfaces roughness requirements 817

Deflection limits for highway bridge superstructure vibration 48 CL-W Truck 53 CL-W Lane Load 54 Maintenance vehicle load 58 Modifications to maximum and minimum effective temperatures 59 Temperature differentials for Type A and C superstructures 60 Pier nose angle and subtended nose angle for calculating forces due to moving ice 68 Dimensions for minimum support lengths 131 DVE for slab-on-girder bridges 188 Definition of Sp and Se 194 Calculation of A 195 Notation for cantilever moments 196 Values of k for calculating transverse vertical shear in shear-connected beam bridges 200 be and b for various cross-sections 204 Effective width of orthotropic deck 206 Failure mechanism for footing 236 Footing under eccentric load 236 Bearing coefficients 237 Eccentricity limit 238 Load inclination reduction factors for bearing resistance,  ’ = 30° 239 Compaction effects 245 Dh and Dv for various shapes of pipe 264 Values of Af 267 Depth of cover, H and Hmin , for soil-metal structures and metal box structures 272 Trench reinforcement for the foundation of pipe-arches 273 Longitudinal seam bolting arrangements 274 Metal box structure dimensional limits 276 Minimum extent of structural backfill for metal box structures 279 Terminology and standard installations for circular precast concrete pipes on embankments 281 Terminology and standard installations for circular precast concrete pipes in trenches 282 Standard installations for concrete box sections on embankments 285

October 2011

xxxA

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© Canadian Standards Association

7.11 — Standard installations for concrete box sections in trenches 286 7.12 — Earth pressure distribution for standard installations of circular concrete pipes (force diagram) 289 7.13 — Lateral earth loads and pressure distribution on concrete box sections due to approaching wheel loads 291 8.1 — Magnitude of thrust 322 8.2 — Eccentricity of curved tendons 323 8.3 — Influence of reinforcement on spacing of diagonal cracks 334 8.4 — Influence of anchorage conditions on effective cross-sectional area of strut 339 8.5 — Reinforcement in cast-in-place deck slab 368 8.6 — Reinforcement for cast-in-place deck slabs designed using the empirical method 369 8.7 — Reinforcement for cast-in-place deck slabs on precast panels 369 8.8 — Edge stiffening at transverse free edges 371 9.1 — Connection of nail-laminated deck to steel beam 413 9.2 — Spliced butt joint 414 9.3 — Details of wood-concrete interface 415 9.4 — Alternative details of wood-concrete interface 416 9.5 — External post-tensioning system 418 9.6 — Internal post-tensioning system 418 9.7 — Protection for external post-tensioning system 423 10.1 — Class 1 and 2 sections in positive moment regions 465 10.2 — Class 1 and 2 sections in negative moment regions 466 10.3 — Class 3 Sections in positive moment regions 468 10.4 — Class 3 Sections in negative moment regions 469 10.5 — Detailing requirements for orthotropic decks 487 10.6 — Detail categories for load-induced fatigue 494 11.1 — Maximum average pressure on a layer of elastomeric bearing at SLS without rotation 548 12.1 — Application of traffic design loads to traffic barriers 562 12.2 — Application of pedestrian and bicycle design loads to barriers 563 14.1 — Level 1 evaluation loads with CL1-W Truck 653 14.2 — Level 2 evaluation loads with CL2-W Truck 654 14.3 — Level 3 evaluation loads with CL3-W Truck 655 14.4 — Deck punching shear for composite slabs 667 14.5 — Deck punching shear for non-composite slabs 668 14.6 — Spacing requirements for minimum reinforcement, mm 670 14.7 — Spacing requirements for minimum reinforcement as a fraction of shear depth 671 14.8 — Posting loads for gross vehicle weight 678 16.1 — Distance between the deck slab and the top of the supporting beam 707 16.2 — Detail of transverse edge stiffening 707 16.3 — Detail of transverse edge stiffening 708 16.4 — Detail of transverse edge stiffening 708 16.5 — Detail of transverse edge stiffening 709 16.6 — External transverse restraining system consisting of connected straps 709 16.7 — External transverse confining system consisting of indirectly connected partially studded straps 710 16.8 — External transverse confining system in longitudinal negative moment regions 710 16.9 — Post-tensioning system for stressed log bridges 716 16.10— Spliced butt joint for logs 717 16.11— Cross-section of a barrier wall reinforced with GFRP 719 16.12— Anchorage methods in the compression zone of externally bonded FRP shear reinforcement 723 16.13— Cross-section of a timber beam with GFRP NSMR 726 16.14— Elevation of timber beam with GFRP sheets for shear strengthening 727 16.15— Elevation of timber beam with GFRP bars for shear strengthening 728

xxxB

October 2011

© Canadian Standards Association

17.1 17.2 17.3 17.4 17.5

— — — — —

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Basic geometric parameters for local buckling 754 Stress distribution in composite sections 780 Stiffened plates and type of stiffeners 787 Detail categories for load-induced fatigue 794 The extent of heat-affected-zones (HAZ) 808

October 2011

xxxC

S6S2-11

© Canadian Standards Association

Technical Committee on the Canadian Highway Bridge Design Code (CAN/CSA-S6-06) This list reflects the Technical Committee membership when CAN/CSA-S6-06 was formally approved.

J. Francis

Nova Scotia Department of Transportation  and Public Works, Halifax, Nova Scotia

Chair

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

Vice-Chair

G. Richard

Ministère des transports du Québec, Québec, Québec

Vice-Chair

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Vice-Chair

H. Yea

Saskatchewan Highways and Transportation, Regina, Saskatchewan

Vice-Chair

A.C. Agarwal

Brampton, Ontario

W.V. Anderson

Delcan Corporation, Markham, Ontario

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

Associate

N. Banthia

University of British Columbia, Vancouver, British Columbia

Associate

F.M. Bartlett

University of Western Ontario, London, Ontario

D. Beaulieu

Centre de recherche industrielle du Québec, Ste-Foy, Québec

G.P. Carlin

Les Ponts Jacques Cartier et Champlain  Incorporée, Longueuil, Québec

M.S. Cheung

University of Ottawa, Ottawa, Ontario

C. Clarke

Alberta Infrastructure and Transportation, Edmonton, Alberta

D. Cogswell

New Brunswick Department of Transportation, Fredericton, New Brunswick

xxxD

Associate

Associate

October 2011

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

D. Dundas

Ontario Ministry of Transportation, Toronto, Ontario

D.J. Evans

Prince Edward Island Department of  Transportation and Public Works, Charlottetown, Prince Edward Island

P. Gauvreau

University of Toronto, Toronto, Ontario

A. Ho

Ontario Ministry of Transportation, Toronto, Ontario

K.C. Johns

Université de Sherbrooke, Sherbrooke, Québec

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

P. Lepper

Canadian Wood Council, Ottawa, Ontario

D. Macleod

Public Works and Government Services Canada, Gatineau, Québec

B. Massicotte

École Polytechnique de Montréal, Montréal, Québec

R. Mathieson

British Columbia Ministry of Transportation, Victoria, British Columbia

R.J. McGrath

Cement Association of Canada, Ottawa, Ontario

D. Mitchell

McGill University, Montréal, Québec

A.A. Mufti

University of Manitoba, Winnipeg, Manitoba

A. Nelson

Manitoba Department of Highways and Transportation, Winnipeg, Manitoba

R.J. Ramsay

UMA Engineering Limited, Edmonton, Alberta

Associate

J.A. Skeet

Dillon Consulting Limited, Calgary, Alberta

Associate

A.F. Wong

Canadian Institute of Steel Construction, Toronto, Ontario

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xxxi, November 2006)

Associate

Associate

Project Manager

xxxi

S6S1-10



© Canadian Standards Association

Technical Committee on the Canadian Highway Bridge Design Code (CSA S6S1-10) Note: This list reflects the Technical Committee membership when CSA S6S1-10 was formally approved.

H. Yea

Saskatchewan Highways and Infrastructure, Regina, Saskatchewan

Chair

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

Vice-Chair

G. Desgagné

Ministère des transports du Québec, Québec, Québec

Vice-Chair

D.J. Evans

Prince Edward Island Department of Transportation and Infrastructure Renewal, Charlottetown, Prince Edward Island

Vice-Chair

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Vice-Chair

A.C. Agarwal

Brampton, Ontario

W.V. Anderson

Delcan Corporation, Markham, Ontario

L. Atkin

Alberta Transportation, Edmonton, Alberta

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

Associate

N. Banthia

University of British Columbia, Vancouver, British Columbia

Associate

F.M. Bartlett

University of Western Ontario, London, Ontario

D. Beaulieu

Université Laval, Québec, Québec

M.S. Cheung

University of Ottawa, Ottawa, Ontario

D. Cogswell

New Brunswick Department of Transportation, Fredericton, New Brunswick

Associate

D. Dundas

Ontario Ministry of Transportation, Toronto, Ontario

Associate

xxxii

May 2010 (Replaces p. xxxii, November 2006)

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

P. Gauvreau

University of Toronto, Toronto, Ontario

Associate

G. Grondin

Unversity of Alberta, Edmonton, Alberta

Associate

A. Ho

Ontario Ministry of Transportation, Toronto, Ontario

K.C. Johns

Université de Sherbrooke, Sherbrooke, Québec

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

P. Lepper

Canadian Wood Council, Ottawa, Ontario

B. Massicotte

École Polytechnique de Montréal, Montréal, Québec

R. Mathieson

British Columbia Ministry of Transportation and Infrastructure, Victoria, British Columbia

R.J. McGrath

Cement Association of Canada, Ottawa, Ontario

D. Mitchell

McGill University, Montréal, Québec

A.A. Mufti

University of Manitoba, Winnipeg, Manitoba

R.J. Ramsay

AECOM, Edmonton, Alberta

G. Richard

Dessau Inc., Québec, Québec

J. Saweczko

Byrne Engineering Inc., Burlington, Ontario

J.A. Skeet

Dillon Consulting Limited, Calgary, Alberta

A.F. Wong

Canadian Institute of Steel Construction, Toronto, Ontario

M. Braiter

CSA, Mississauga, Ontario

October 2011 (Replaces p. xxxiii, May 2010)

Associate

Associate

Project Manager

xxxiii

S6S2-11



© Canadian Standards Association

Technical Committee on the Canadian Highway Bridge Design Code (CSA S6S2-11) This list reflects the Technical Committee membership when CSA S6S2-11 was formally approved.

H. Yea

Saskatchewan Highways and Infrastructure, Regina, Saskatchewan

Chair

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

Vice-Chair

G. Desgagné

Ministère des transports du Québec, Québec, Québec

Vice-Chair

D.J. Evans

Prince Edward Island Department of Transportation and Infrastructure Renewal, Charlottetown, Prince Edward Island

Vice-Chair

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Vice-Chair

A.C. Agarwal

Brampton, Ontario

W.V. Anderson

Delcan Corporation, Markham, Ontario

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

Associate

N. Banthia

University of British Columbia, Vancouver, British Columbia

Associate

F.M. Bartlett

University of Western Ontario, London, Ontario

D. Beaulieu

Université Laval, Québec, Québec

M.S. Cheung

University of Ottawa, Ottawa, Ontario

D. Dixon

McCormick Rankin Corporation, Mississauga, Ontario

Associate

D. Dundas

Ontario Ministry of Transportation, Toronto, Ontario

Associate

R. Eden

Manitoba Infrastructure and Transportation, Winnipeg, Manitoba

Associate

S. Eisan

Nova Scotia Transportation and Infrastructure Renewal, Halifax, Nova Scotia

xxxiv

October 2011 (Replaces p. xxxiv, May 2010)

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

P. Gauvreau

University of Toronto, Toronto, Ontario

Associate

G. Grondin

Unversity of Alberta, Edmonton, Alberta

Associate

G. Hewus

Federal Bridge Corporation, Ottawa, Ontario

Associate

A. Ho

Ontario Ministry of Transportation, Toronto, Ontario

A. Ikpong

Yukon Department of Highways and Public Works, Whitehorse, Yukon

K.C. Johns

Sherbrooke, Québec

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

A. Lanteigne

Government of the Northwest Territories, Yellowknife, Northwest Territories

P. Lepper

Canadian Wood Council, Ottawa, Ontario

B. Massicotte

École Polytechnique de Montréal, Montréal, Québec

R. Mathieson

British Columbia Ministry of Transportation and Infrastructure, Victoria, British Columbia

R.J. McGrath

Cement Association of Canada, Ottawa, Ontario

D. Mitchell

McGill University, Montréal, Québec

A.A. Mufti

University of Manitoba, Winnipeg, Manitoba

R.J. Ramsay

AECOM, Edmonton, Alberta

G. Richard

Dessau Inc., Québec, Québec

J. Saweczko

Byrne Engineering Inc., Burlington, Ontario

A.F. Wong

Canadian Institute of Steel Construction, Toronto, Ontario

M. Braiter

CSA, Mississauga, Ontario

October 2011

Associate

Associate

Associate

Associate

Project Manager

xxxivA

S6S2-11

© Canadian Standards Association

Subcommittee on Section 1 — General A. Ho

Ontario Ministry of Transportation, Toronto, Ontario

J. Doering

University of Manitoba, Winnipeg, Manitoba

H. Farghaly

Ontario Ministry of Transportation, St. Catharines, Ontario

R. Haynes

Ontario Ministry of Transportation, St. Catharines, Ontario

R. Richardson

Manitoba Department of Highways and Transportation, Winnipeg, Manitoba

D.M. Tran

Ministère des transports du Québec, Québec, Québec

R. Walters

Stantec Consulting Limited, Edmonton, Alberta

E. Waschuk

Alberta Infrastructure and Transportation, Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

xxxivB

Chair

Project Manager

October 2011

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 2 — Durability N. Banthia

University of British Columbia, Vancouver, British Columbia

G.E. Brudermann

Frido Consulting, Halfmoon Bay, British Columbia

P.D. Carter

CH2M HILL Canada, Vancouver, British Columbia

D. Conte

Ontario Ministry of Transportation, Toronto, Ontario

O.E. Gjorv

Norwegian University of Science and Technology, Trondheim, Norway

J. Kroman

City of Calgary, Calgary, Alberta

Z. Lounis

National Research Council Canada, Ottawa, Ontario

P. McGrath

McGrath Engineering Ltd., North Vancouver, British Columbia

S. Mindess

University of British Columbia, Vancouver, British Columbia

K. Sakai

Kagawa University, Takamatsu, Japan

G. Tadros

STECO Engineering Ltd., Calgary, Alberta

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xxxv, November 2006)

Chair

Project Manager

xxxv

S6S1-10

© Canadian Standards Association

Subcommittee on Section 3 — Loads (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

A.C. Agarwal

Brampton, Ontario

A. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

P. King

University of Western Ontario, London, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Mitchell

McGill University, Montréal, Québec

R.H. Pion

Public Works and Government Services Canada, Gatineau, Québec

G. Van Der Vinne

Northwest Hydraulic Consultants Ltd., Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

xxxvi

Chair

Project Manager

May 2010 (Replaces p. xxxvi, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 3 — Loads (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

A.C. Agarwal

Brampton, Ontario

Chair

A. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

Secretary

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

P. King

University of Western Ontario, London, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Mitchell

McGill University, Montréal, Québec

G. Van Der Vinne

Northwest Hydraulic Consultants Ltd., Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xxxvii, November 2006)

Project Manager

xxxvii

S6S1-10

© Canadian Standards Association

Subcommittee on Section 4 — Seismic design (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

D. Mitchell

McGill University, Montréal, Québec

U.D. Atukorala

Golder Associates Ltd., Burnaby, British Columbia

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

M. Bruneau

University at Buffalo, Buffalo, New York, USA

A. Heidebrecht

McMaster University, Hamilton, Ontario

D. Kennedy

Associated Engineering Ltd., Burnaby, British Columbia

N. Theodor

Ontario Ministry of Transportation, St. Catharines, Ontario

R. Tremblay

École Polytechnique de Montréal, Montréal, Québec

S. Zhu

Buckland & Taylor Ltd., North Vancouver, British Columbia

M. Braiter

CSA, Mississauga, Ontario

xxxviii

Chair

Project Manager

May 2010 (Replaces p. xxxviii, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 4 — Seismic design (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

D. Mitchell

McGill University, Montréal, Québec

U.D. Atukorala

Golder Associates Ltd., Burnaby, British Columbia

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

M. Bruneau

University at Buffalo, Buffalo, New York, USA

A. Heidebrecht

McMaster University, Hamilton, Ontario

D. Kennedy

Associated Engineering Ltd., Burnaby, British Columbia

N. Theodor

Ontario Ministry of Transportation, St. Catharines, Ontario

R. Tremblay

École Polytechnique de Montréal, Montréal, Québec

S. Zhu

Buckland & Taylor Ltd., North Vancouver, British Columbia

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xxxix, November 2006)

Chair

Project Manager

xxxix

S6S1-10

© Canadian Standards Association

Subcommittee on Section 5 — Methods of analysis (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

B. Massicotte

École Polytechnique de Montréal, Montréal, Québec

J. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

T. Chicoine

SNC-Lavalin Inc., Montréal, Québec

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

J. Newhook

Dalhousie University, Halifax, Nova Scotia

S. Sabanathan

Ontario Ministry of Transportation, St. Catharines, Ontario

M. Talbot

Ministère des transports du Québec, Québec, Québec

M. Braiter

CSA, Mississauga, Ontario

xl

Chair

Project Manager

May 2010 (Replaces p. xl, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 5 — Methods of analysis (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

B. Massicotte

École Polytechnique de Montréal, Montréal, Québec

J. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

T. Chicoine

Buckland & Taylor Ltd., North Vancouver, British Columbia

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

R. Hasan

Ontario Ministry of Transportation, St. Catharines, Ontario

M. Talbot

Ministère des transports du Québec, Québec, Québec

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xli, November 2006)

Chair

Project Manager

xli

S6S1-10

© Canadian Standards Association

Subcommittee on Section 6 — Foundations (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

D. Dundas

Ontario Ministry of Transportation, Toronto, Ontario

A. Altaee

Urkkada Technology, Ottawa, Ontario

U.D. Atukorala

Golder Associates Ltd., Burnaby, British Columbia

P. Branco

Thurber Engineering Limited, Oakville, Ontario

G. Fenton

Dalhousie University, Halifax, Nova Scotia

R. Green

Waterloo, Ontario

I. Husain

Ontario Ministry of Transportation, St. Catharines, Ontario

I. Leclerc

Ministère des transports du Québec, Québec, Québec

P. Ojala

Lea Consulting Limited, Markham, Ontario

D. Woeller

ConeTec Investigations Ltd., Vancouver, British Columbia

M. Braiter

CSA, Mississauga, Ontario

xlii

Chair

Project Manager

May 2010 (Replaces p. xlii, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 6 — Foundations (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

D. Dundas

Ontario Ministry of Transportation, Toronto, Ontario

A. Altaee

Urkkada Technology, Ottawa, Ontario

U.D. Atukorala

Golder Associates Ltd., Burnaby, British Columbia

P. Branco

Thurber Engineering Limited, Oakville, Ontario

G. Fenton

Dalhousie University, Halifax, Nova Scotia

R. Green

Waterloo, Ontario

I. Husain

Ontario Ministry of Transportation, St. Catharines, Ontario

I. Leclerc

Ministère des transports du Québec, Québec, Québec

P. Ojala

Lea Consulting Limited, Markham, Ontario

D. Woeller

ConeTec Investigations Ltd., Vancouver, British Columbia

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xliii, November 2006)

Chair

Project Manager

xliii

S6S1-10

© Canadian Standards Association

Subcommittee on Section 7 — Buried structures B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

G. Abdel-Sayed

Bloomfield Hills, Michigan, USA

J. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

K. Bontius

Hatch, Mott & MacDonald, Mississauga, Ontario

W. Brockbank

Reinforced Earth Company Ltd., Mississauga, Ontario

M. Gergely

Ontario Ministry of Transportation, St. Catharines, Ontario

W. Kenedi

Ontario Ministry of Transportation, St. Catharines, Ontario

E. Kling

Centennial Concrete Pipe & Products Inc., Cambridge, Ontario

I. Leclerc

Ministère des transports du Québec, Québec, Québec

J. Meyboom

Delcan Corporation, New Westminster, British Columbia

C. Mirza

Toronto, Ontario

I. Moore

Queen’s University, Kingston, Ontario

T. Morrison

Atlantic Industries Limited, Cambridge, Ontario

J. Newhook

Dalhousie University, Halifax, Nova Scotia

P. Sheehan

Armtec Limited Partnership, Guelph, Ontario

M. Braiter

CSA, Mississauga, Ontario

xliv

Chair

Project Manager

May 2010 (Replaces p. xliv, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 8 — Concrete structures (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

P. Gauvreau

University of Toronto, Toronto, Ontario

D. Bernard

Ministère des transports du Québec, Québec, Québec

M.P. Collins

University of Toronto, Toronto, Ontario

H. Ibrahim

Buckland & Taylor Ltd., North Vancouver, British Columbia

W. Leblanc

Con-Force Structures Limited, Calgary, Alberta

R.J. McGrath

Cement Association of Canada, Ottawa, Ontario

M. Meleka

Ontario Ministry of Transportation, St. Catharines, Ontario

D.M. Rogowsky

UMA Engineering Ltd., Edmonton, Alberta

R. Stofco

McCormick Rankin Corporation, Mississauga, Ontario

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xlv, November 2006)

Chair

Project Manager

xlv

S6S1-10



© Canadian Standards Association

Subcommittee on Section 8 — Concrete structures (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

P. Gauvreau

University of Toronto, Toronto, Ontario

D. Bernard

Ministère des transports du Québec, Québec, Québec

M.P. Collins

University of Toronto, Toronto, Ontario

S. Goulet

Ministère des transports du Québec, Québec, Québec

H. Ibrahim

Buckland & Taylor Ltd., North Vancouver, British Columbia

W. Leblanc

Con-Force Structures Limited, Calgary, Alberta

R.J. McGrath

Cement Association of Canada, Ottawa, Ontario

M. Meleka

Ontario Ministry of Transportation, St. Catharines, Ontario

D.M. Rogowsky

UMA Engineering Ltd., Edmonton, Alberta

R. Stofco

McCormick Rankin Corporation, Mississauga, Ontario

M. Braiter

CSA, Mississauga, Ontario

xlvi

Chair

Project Manager

May 2010 (Replaces p. xlvi, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 9 — Wood structures K.C. Johns

Université de Sherbrooke, Sherbrooke, Québec

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

L.M. Bélanger

Ministère des transports du Québec, Québec, Québec

R.M.G. Britton

University of Manitoba, Winnipeg, Manitoba

G.E. Brudermann

Frido Consulting, Halfmoon Bay, British Columbia

R.J. Eden

Manitoba Floodway Authority, Winnipeg, Manitoba

M. Erki

Royal Military College of Canada, Kingston, Ontario

R.O. Foschi

University of British Columbia, Vancouver, British Columbia

R. Krisciunas

Ontario Ministry of Transportation, Thunder Bay, Ontario

P. Lepper

Canadian Wood Council, Ottawa, Ontario

I. Sturrock

British Columbia Ministry of Transportation, Victoria, British Columbia

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xlvii, November 2006)

Chair

Project Manager

xlvii

S6S1-10

© Canadian Standards Association

Subcommittee on Section 10 — Steel structures (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

D. Beaulieu

Centre de recherche industrielle du Québec, Ste-Foy, Québec

D. Francis

Supreme Steel Ltd., Edmonton, Alberta

G. Grondin

University of Alberta, Edmonton, Alberta

H. Hawk

Delcan Corporation, Calgary, Alberta

J. Labbé

Ministère des transports du Québec, Québec, Québec

N. Theodor

Ontario Ministry of Transportation, St. Catharines, Ontario

R. Vincent

Canam Group Inc., Boucherville, Québec

A.F. Wong

Canadian Institute of Steel Construction, Toronto, Ontario

M. Braiter

CSA, Mississauga, Ontario

xlviii

Chair

Project Manager

May 2010 (Replaces p. xlviii, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 10 — Steel structures (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

G. Grondin

University of Alberta, Edmonton, Alberta

Chair

R. Vincent

Canam Group Inc., Boucherville, Québec

Vice-Chair

H. Hawk

Delcan Corporation, Calgary, Alberta

P. King

Rapid-Span Structures, Armstrong, British Columbia

J. Labbé

Ministère des transports du Québec, Québec, Québec

N. Theodor

Ontario Ministry of Transportation, St. Catharines, Ontario

E. Whalen

Canadian Institute of Steel Construction, Markham, Ontario

A.F. Wong

Canadian Institute of Steel Construction, Markham, Ontario

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. xlix, November 2006)

Project Manager

xlix

S6S1-10

© Canadian Standards Association

Subcommittee on Section 11 — Joints and bearings J.A. Skeet

Dillon Consulting Limited, Calgary, Alberta

J. Labbé

Ministère des transports du Québec, Québec, Québec

R. Mihaljevic

Ontario Ministry of Transportation, St. Catharines, Ontario

N. Patel

Ontario Ministry of Transportation, St. Catharines, Ontario

J.F. Reysset

Goodco Ltée, Laval, Québec

R. Yu

Alberta Infrastructure and Transportation, Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

l

Chair

Project Manager

May 2010 (Replaces p. l, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 12 — Barriers and highway accessory supports R.J. Ramsay

UMA Engineering Limited, Edmonton, Alberta

D. Beaulieu

Centre de recherche industrielle du Québec, Ste-Foy, Québec

M. Blouin

Ministère des transports du Québec, Québec, Québec

R. Haynes

Ontario Ministry of Transportation, St. Catharines, Ontario

M. Vallières

Ministère des transports du Québec, Québec, Québec

R. Yu

Alberta Infrastructure and Transportation, Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. li, November 2006)

Chair

Project Manager

li

S6S1-10

© Canadian Standards Association

Subcommittee on Section 13 — Movable bridges T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Campbell

Klohn-Krippen Consultants Ltd., Vancouver, British Columbia

R. Clayton

Byrne Engineering Inc., Burlington, Ontario

J. Crabb

Delcan Corporation, Markham, Ontario

D. Dixon

McCormick Rankin Corporation, Mississauga, Ontario

L. Huang

Modjeski and Masters, Mechanicsburg, Pennsylvania, USA

Q. Islam

Ontario Ministry of Transportation, Kingston, Ontario

W. McCraken

Byrne Engineering Inc., Burlington, Ontario

J. Saweczko

Byrne Engineering Inc., Burlington, Ontario

P.M. Skelton

Hardesty & Hanover, New York, New York, USA

A. Zaki

SNC-Lavalin Inc., Montréal, Québec

M. Braiter

CSA, Mississauga, Ontario

lii

Chair

Project Manager

May 2010 (Replaces p. lii, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 14 — Evaluation (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

F.M. Bartlett

University of Western Ontario, London, Ontario

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

B. Higgins

CBCL Limited, Halifax, Nova Scotia

W. Kenedi

Ontario Ministry of Transportation, St. Catharines, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

J. Meyboom

Delcan Corporation, New Westminster, British Columbia

P. Ojala

Lea Consulting Limited, Markham, Ontario

R.J. Ramsay

UMA Engineering Limited, Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. liii, November 2006)

Chair

Project Manager

liii

S6S1-10



© Canadian Standards Association

Subcommittee on Section 14 — Evaluation (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

D. Bagnariol

Ontario Ministry of Transportation, St. Catharines, Ontario

F.M. Bartlett

University of Western Ontario, London, Ontario

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

B. Higgins

CBCL Limited, Halifax, Nova Scotia

W. Kenedi

Ontario Ministry of Transportation, St. Catharines, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

R.J. Ramsay

AECOM, Edmonton, Alberta

M. Braiter

CSA, Mississauga, Ontario

liv

Chair

Project Manager

May 2010 (Replaces p. liv, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Subcommittee on Section 15 — Rehabilitation and repair F.M. Bartlett

University of Western Ontario, London, Ontario

D. Dixon

McCormick Rankin Corporation, Mississauga, Ontario

L. Feldman

University of Saskatchewan, Saskatoon, Saskatchewan

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

D. Lai

Ontario Ministry of Transportation, St. Catharines, Ontario

K.W. Neale

Université de Sherbrooke, Sherbrooke, Québec

M. Braiter

CSA, Mississauga, Ontario

May 2010 (Replaces p. lv, November 2006)

Chair

Project Manager

lv

S6S1-10

© Canadian Standards Association

Subcommittee on Section 16 — Fibre-reinforced structures (CAN/CSA-S6-06) Note: This list reflects the Subcommittee membership when CAN/CSA-S6-06 was formally approved.

A.A. Mufti

University of Manitoba, Winnipeg, Manitoba

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

N. Banthia

University of British Columbia, Vancouver, British Columbia

B. Benmokrane

Université de Sherbrooke, Sherbrooke, Québec

G. Desgagné

Ministère des transports du Québec, Québec, Québec

R.J. Eden

Manitoba Floodway Authority, Winnipeg, Manitoba

M. Erki

Royal Military College of Canada, Kingston, Ontario

V. Karbhari

University of California at San Diego, La Jolla, California, USA

J. Kroman

City of Calgary, Calgary, Alberta

D. Lai

Ontario Ministry of Transportation, St. Catharines, Ontario

A. Machida

Saitama University, Urawa, Japan

K.W. Neale

Université de Sherbrooke, Sherbrooke, Québec

G. Tadros

STECO Engineering Ltd., Calgary, Alberta

B. Taljsten

BYG-DTU, Lyngby, Denmark

M. Braiter

CSA, Mississauga, Ontario

lvi

Chair

Project Manager

May 2010

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 16 — Fibre-reinforced structures (CSA S6S1-10) Note: This list reflects the Subcommittee membership when CSA S6S1-10 was formally approved.

A.A. Mufti

University of Manitoba, Winnipeg, Manitoba

Chair

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

Secretary

N. Banthia

University of British Columbia, Vancouver, British Columbia

B. Benmokrane

Université de Sherbrooke, Sherbrooke, Québec

G. Desgagné

Ministère des transports du Québec, Québec, Québec

R.J. Eden

Manitoba Floodway Authority, Winnipeg, Manitoba

M. Erki

Royal Military College of Canada, Kingston, Ontario

V. Karbhari

University of California at San Diego, La Jolla, California, USA

J. Kroman

City of Calgary, Calgary, Alberta

D. Lai

Ontario Ministry of Transportation, St. Catharines, Ontario

A. Machida

Saitama University, Urawa, Japan

K.W. Neale

Université de Sherbrooke, Sherbrooke, Québec

J. Newhook

Dalhousie University, Halifax, Nova Scotia

S. Shamim

University of Toronto, Toronto, Ontario

G. Tadros

STECO Engineering Ltd., Calgary, Alberta

May 2010

lvii

S6S1-10

© Canadian Standards Association

B. Taljsten

BYG-DTU, Lyngby, Denmark

M. Braiter

CSA, Mississauga, Ontario

lviii

Project Manager

May 2010

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association



Subcommittee on Section 17 — Aluminum structures D. Beaulieu

Université Laval, Québec, Québec

A. Agarwal

Brampton, Ontario

S. Bédard

Dessau Inc. Laval, Québec

K. Y. Chu

Ontario Ministry of Transportation, St. Catharines, Ontario

A. de la Chevrotière

MaadiGroup Inc . Montréal, Québec

K. Gong

Constellium, Novi, Minnesota, USA

S. Guravich

Skarborn Engineering Limited, Fredericton, New Brunswick

F. Jutras

Groupe Conseil Roche Ltd, Ste-Foy, Québec

R. Kissell

The TGB Partnership, Hillsborough, North Carolina, USA

C. Marsh

Victoria, British Columbia

F. Mazzolani

Universita degli Studi di Napoli, Naples, Italy

B. Partridge

CWB Group, Milton, Ontario

S. Safadel

Ontario Power Generation Inc. Bowmanville, Ontario

M. Vallières

Ministère des transports du Québec, Québec, Québec

S. Walbridge

University of Waterloo, Waterloo, Ontario

E. Whalen

Canadian Institute of Steel Construction, Markham, Ontario

A. Ikpong

Yukon Department of Highways and Public Works, Whitehorse, Yukon

M. Braiter

CSA, Mississauga, Ontario

October 2011

Chair

Project Manager

lviiiA

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Code Calibration Task Force (CAN/CSA-S6-06) Note: This list reflects the Code Calibration Task Force membership when CAN/CSA-S6-06 was formally approved.

A.C. Agarwal

Brampton, Ontario

A. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Becker

Golder Associates Ltd., Calgary, Alberta

R.O. Foschi

University of British Columbia, Vancouver, British Columbia

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

H. Hong

University of Western Ontario, London, Ontario

P. King

University of Western Ontario, London, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Mitchell

McGill University, Montréal, Québec

A.S. Nowak

University of Nebraska, Lincoln, Nebraska, USA

M. Braiter

CSA, Mississauga, Ontario

May 2010

Chair

Project Manager

lix

S6S1-10



© Canadian Standards Association

Code Calibration Task Force (CSA S6S1-10) Note: This list reflects the Code Calibration Task Force membership when CSA S6S1-10 was formally approved.

A.C. Agarwal

Brampton, Ontario

Chair

A. Au

Ontario Ministry of Transportation, St. Catharines, Ontario

Secretary

D. Becker

Golder Associates Ltd., Calgary, Alberta

D.P. Gagnon

Buckland & Taylor Ltd., North Vancouver, British Columbia

H. Hong

University of Western Ontario, London, Ontario

P. King

University of Western Ontario, London, Ontario

C. Lam

Ontario Ministry of Transportation, St. Catharines, Ontario

D. Mitchell

McGill University, Montréal, Québec

A.S. Nowak

University of Nebraska, Lincoln, Nebraska, USA

I. Smith

University of New Brunswick, Fredericton, New Brunswick

M. Braiter

CSA, Mississauga, Ontario

lx

Project Manager

May 2010

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

Editorial Task Force M. Erki

Royal Military College of Canada, Kingston, Ontario

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

L.G. Jaeger

Halifax, Nova Scotia

M. Braiter

CSA, Mississauga, Ontario

May 2010

Chair

Project Manager

lxi

S6S1-10

© Canadian Standards Association

French Translation Task Force (CAN/CSA-S6-06) Note: This list reflects the French Translation Task Force membership when CAN/CSA-S6-06 was formally approved.

G. Desgagné

Ministère des transports du Québec, Québec, Québec

L.M. Bélanger

Ministère des transports du Québec, Québec, Québec

D. Bernard

Ministère des transports du Québec, Québec, Québec

M. Blouin

Ministère des transports du Québec, Québec, Québec

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

J. Labbé

Ministère des transports du Québec, Québec, Québec

M. Lacroix

Ministère des transports du Québec, Québec, Québec

J. Prévost

Ministère des transports du Québec, Québec, Québec

M. Savard

Ministère des transports du Québec, Québec, Québec

M. Vallières

Ministère des transports du Québec, Québec, Québec

M. Braiter

CSA, Mississauga, Ontario

lxii

Chair

Project Manager

May 2010

© Canadian Standards Association



Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

French Translation Task Force (CSA S6S1-10) Note: This list reflects the French Translation Task Force membership when CSA S6S1-10 was formally approved.

G. Desgagné

Ministère des transports du Québec, Québec, Québec

L.M. Bélanger

Ministère des transports du Québec, Québec, Québec

D. Bernard

Ministère des transports du Québec, Québec, Québec

M. Blouin

Ministère des transports du Québec, Québec, Québec

D. Boulet

Ministère des transports du Québec, Québec, Québec

J.P. Grenier

Ministère des transports du Québec, Québec, Québec

J. Labbé

Ministère des transports du Québec, Québec, Québec

M. Lacroix

Ministère des transports du Québec, Québec, Québec

J. Prévost

Ministère des transports du Québec, Québec, Québec

M. Savard

Ministère des transports du Québec, Québec, Québec

M. Talbot

Ministère des transports du Québec, Québec, Québec

M. Vallières

Ministère des transports du Québec, Québec, Québec

M. Braiter

CSA, Mississauga, Ontario

May 2010

Chair

Project Manager

lxiii

S6S1-10

© Canadian Standards Association

Regulatory Authority Committee (CAN/CSA-S6-06) Note: This list reflects the Regulatory Authority Committee membership when CAN/CSA-S6-06 was formally approved.

G. Richard

Ministère des transports du Québec, Québec, Québec

Chair

J. Francis

Nova Scotia Department of Transportation and Public Works, Halifax, Nova Scotia

Vice-Chair

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Vice-Chair

B. Bakht

JMBT Structures Research Inc., Toronto, Ontario

Associate

G.P. Carlin

Les Ponts Jacques Cartier et Champlain Incorporée, Longueuil, Québec

C. Clarke

Alberta Infrastructure and Transportation, Edmonton, Alberta

D. Cogswell

New Brunswick Department of Transportation, Fredericton, New Brunswick

D.J. Evans

Prince Edward Island Department of  Transportation and Public Works, Charlottetown, Prince Edward Island

A. Ikpong

Yukon Department of Highways and Public Works, Whitehorse, Yukon

D. Macleod

Public Works and Government Services Canada, Gatineau, Québec

R. Mathieson

British Columbia Ministry of Transportation, Victoria, British Columbia

D. Power

Newfoundland and Labrador Department of Transportation and Works, St. John’s, Newfoundland and Labrador

R. Richardson

Manitoba Department of Highways and Transportation, Winnipeg, Manitoba

D.R. Sitland

Government of Nunavut, Iqaluit, Nunavut

T. Williams

Government of the Northwest Territories, Yellowknife, Northwest Territories

lxiv

May 2010

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

H. Yea

Saskatchewan Highways and Transportation, Regina, Saskatchewan

M. Braiter

CSA, Mississauga, Ontario

May 2010

Project Manager

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Regulatory Authority Committee (CSA S6S1-10) Note: This list reflects the Regulatory Authority Committee membership when CSA S6S1-10 was formally approved.

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Chair

G. Desgagné

Ministère des transports du Québec, Québec, Québec

Vice-Chair

R. Mathieson

British Columbia Ministry of Transportation and Infrastructure, Victoria, British Columbia

Vice-Chair

L. Atkin

Alberta Transportation, Edmonton, Alberta

D. Cogswell

New Brunswick Department of Transportation, Fredericton, New Brunswick

R. Eden

Manitoba Department of Infrastructure and Transportation, Winnipeg, Manitoba

S. Eisan

Nova Scotia Department of Transportation and Infrastructure Renewal, Halifax, Nova Scotia

D.J. Evans

Prince Edward Island Department of Transportation and Infrastructure Renewal, Charlottetown, Prince Edward Island

G. Hewas

The Federal Bridge Corporation, Ottawa, Ontario

A. Ikpong

Yukon Department of Highways and Public Works, Whitehorse, Yukon

A. Lanteigne

Government of the Northwest Territories, Yellowknife, Northwest Territories

D. Power

Newfoundland and Labrador Department of Transportation and Works, St. John’s, Newfoundland and Labrador

H. Yea

Saskatchewan Highways and Transportation, Regina, Saskatchewan

M. Braiter

CSA, Mississauga, Ontario

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

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Regulatory Authority Committee (CSA S6S2-11) This list reflects the Regulatory Authority Committee membership when CSA S6S2-11 was formally approved.

T.B. Tharmabala

Ontario Ministry of Transportation, St. Catharines, Ontario

Chair

G. Desgagné

Ministère des transports du Québec, Québec, Québec

Vice-Chair

R. Mathieson

British Columbia Ministry of Transportation and Infrastructure, Victoria, British Columbia

Vice-Chair

R. Eden

Manitoba Department of Infrastructure and Transportation, Winnipeg, Manitoba

S. Eisan

Nova Scotia Department of Transportation and Infrastructure Renewal, Halifax, Nova Scotia

D.J. Evans

Prince Edward Island Department of Transportation and Infrastructure Renewal, Charlottetown, Prince Edward Island

G. Hewus

The Federal Bridge Corporation, Ottawa, Ontario

A. Ikpong

Yukon Department of Highways and Public Works, Whitehorse, Yukon

A. Lanteigne

Government of the Northwest Territories, Yellowknife, Northwest Territories

D. Power

Newfoundland and Labrador Department of Transportation and Works, St. John’s, Newfoundland and Labrador

V. Sahni

Public Works Government Services Canada, Ottawa, Ontario

H. Yea

Saskatchewan Highways and Transportation, Regina, Saskatchewan

M. Braiter

CSA, Mississauga, Ontario

October 2011

Project Manager

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Preface This is the tenth edition of CAN/CSA-S6, Canadian Highway Bridge Design Code. It supersedes the previous edition published in 2000, which amalgamated and superseded CAN/CSA-S6-88, Design of Highway Bridges, and the Ontario Ministry of Transportation’s OHBDC-91-01, Ontario Highway Bridge Design Code, 3rd ed. Earlier editions of the CSA Standard were published in 1978, 1974, 1966, 1952, 1938, 1929, and 1922. Earlier editions of the Ontario Highway Bridge Design Code were published in 1983 and 1979 by the Ontario Ministry of Transportation. This Code uses the limit states design approach and reflects current design conditions across Canada as well as research activity since the publication of the previous edition. Several design aspects are addressed for the first time in this edition and a more detailed treatment of many areas is provided. This Code has been written to be applicable in all provinces and territories. Section 1 (“General”) specifies general requirements and includes definitions and a reference publications clause applicable throughout this Code. It also specifies geometric requirements, based in part on the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads (1999), and hydraulic design requirements, based in part on the Transportation Association of Canada’s Guide to Bridge Hydraulics, 2nd ed. (2001). There are also provisions covering durability, economics, environmental considerations, aesthetics, safety, maintenance, and maintenance inspection access. Section 2 (“Durability”) addresses durability aspects of materials used in the construction of highway bridges, culverts, and other structures located in transportation corridors. The durability requirements for all of the materials are based on common principles applicable to the deterioration mechanisms for each material, the environmental conditions to which the materials are subjected, and the protective measures and detailing requirements needed to limit deterioration to acceptable levels. Section 3 (“Loads”) specifies loading requirements for the design of new bridges, including requirements for permanent loads, live loads, and miscellaneous transitory and exceptional loads (but excluding seismic loads). The 625 kN truck load model and corresponding lane load model are specified as the minima for interprovincial transportation and are based on current Canadian legal loads. Ship collision provisions are also included in Section 3. Section 3 no longer specifies limits on the span lengths for application of the truck and lane loads. Accordingly, long-span requirements have been developed and appear in Section 3 and elsewhere in this Code (these requirements, however, should not be considered comprehensive). Section 3 covers long-span live loading and addresses wind tunnel testing for aerodynamic effects. Section 4 (“Seismic design”) specifies seismic design requirements for new bridges. These are based primarily on AASHTO (American Association of State Highway and Transportation Officials) LRFDEM-3-M, AASHTO LRFD Bridge Design Specifications, 3rd ed. (2005). Section 4 differs from AASHTO LRFDEM-3-M, however, by providing a more extensive treatment of the importance and response modification factors, new design and detailing requirements for structural steel ductile substructure elements, and design provisions for seismic base isolation. Section 4 also includes design provisions for the seismic evaluation of existing bridges and provisions pertaining to the seismic rehabilitation of existing bridges. Section 5 (“Methods of analysis”) specifies requirements for analyzing the basic superstructure of a bridge. In its methods for simplified analysis of bridge superstructures, a bridge is treated as a single beam and force effects are averaged over the width of the bridge and subsequently amplified to calculate the true intensity. Distribution factors are based on research conducted up to the late 1990s. Simplified elastic methods are included for the analysis of transverse effects. Refined methods of analysis for short-, medium-, and long-span bridges are also addressed. Section 6 (“Foundations”) is based, as in the previous edition, on the use of global resistance factors. Section 6 employs the limit states design approach, in which the term “resistance” is applied to the strength or capacity of the soil or rock at the ultimate limit state and the term “reaction” is associated with the serviceability limit state and is indicative of a particular deformation. Section 6 also emphasizes the importance of communication between the bridge structural engineer and the geotechnical engineer at all stages of a project.

October 2011 (Replaces p. lxvii, May 2010)

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Section 7 (“Buried structures”) deals with soil-metal structures with shallow corrugated plates in which thrust is the dominant force in the metal plates as well as soil-metal structures with deep corrugated plates and metal box structures in which flexural effects are also considered in the design of the metal plates. Provisions have been added for reinforced concrete precast and cast-in-place structures, including pipes, box sections, and segmental structures. Section 7 also specifies requirements for determining the properties and dimensions of the engineered soil and non-soil components and addresses construction supervision and construction procedures for soil components. Section 8 (“Concrete structures”) covers reinforced and partially and fully prestressed concrete components (including deck slabs) made of normal-density, semi-low-density, and high-density concrete of a strength varying from 30 to 80 MPa. Compression field theory is used for proportioning for shear and for torsion combined with flexure. The strut-and-tie approach is used for proportioning regions where the plane sections assumption is not applicable. Section 9 (“Wood structures”) specifies properties for materials and fastenings that are consistent with CAN/CSA-O86-09, Engineering Design in Wood, and includes data for structural composite lumber. Its provisions related to shear and compression, load distribution, design factors (in many cases), and laminated wood decks are essentially unchanged from those of the previous edition. The shear force concept has been reintroduced for the shear design of sawn wood members and the specified strength values in shear have been increased, in accordance with CAN/CSA-O86-09. In addition, the factors for load-sharing systems have changed. Section 10 (“Steel structures”) specifies the majority of this Code’s design requirements for steel structures (with the exception of some seismic requirements specified in Section 4). Construction requirements that can have an impact on the resistance factors used in Section 10 are specified in Clause 10.24. Because this Code has been expanded to include long-span bridges, cables and arches are now dealt with. In addition, durability is now addressed much more fully and clauses dealing with beams and girders, composite beams and girders, horizontally curved girders, orthotropic decks, fatigue, and construction have been revised. Section 11 (“Joints and bearings”) covers the deck joints and bearings most commonly used in Canada. Section 12 (“Barriers and highway accessory supports”) specifies crash test requirements for barriers and breakaway highway accessory supports. Crash testing may be waived for barrier and accessory support designs that have a successful in-service performance record. Performance levels alternative to those specified in Section 12 are permitted if approved by the regulatory authority. Section 13 (“Movable bridges”) specifies requirements for the design, construction, and operation of conventional movable bridges. Although the structural design aspects are based on the limit states design approach, the mechanical systems design aspects follow the working stress principle used in North American industry. Section 14 (“Evaluation”) includes new provisions concerning the three-level evaluation system, evaluation of deck slabs, and detailed evaluation from bridge testing. The provisions on the strength of wood members and the shear resistance of concrete have been improved. Another category of permit vehicle (Permit — Annual or project [PA]) has been added. An optional probability-based mean load method that uses site-specific load and resistance information for more accurate evaluation is also provided. As in the previous edition, a more conventional approach to determining material grades from small samples is used in place of the Baye’s theorem approach in CAN/CSA-S6-88. Section 15 (“Rehabilitation and repair”) specifies rehabilitation design requirements and provides guidance on the selection of loads and load factors for rehabilitation that is based on the intended use of the bridge following rehabilitation. Section 16 (“Fibre-reinforced structures”) specifies design requirements for a limited number of structural components containing either high- or low-modulus fibres. The high-modulus fibres (aramid, carbon, and glass) are employed in fibre-reinforced polymers (FRPs), which are used as replacements for steel bars and tendons. The low-modulus fibres are used for controlling cracks in concrete. Section 16 covers concrete beams and slabs, concrete deck slabs, and stressed wood decks. In this edition, Section 16 includes new design provisions that permit glass-fibre-reinforced polymer to be used as primary reinforcement and as tendons in concrete. Section 17 (Aluminum Structures) specifies the design requirements for aluminum highway and pedestrian structures.

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© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Other new provisions in Section 16 permit the rehabilitation of concrete and timber structures using externally bonded FRP systems or near-surface-mounted reinforcement. The provisions concerning fibre-reinforced concrete deck slabs in the previous edition have been reorganized for this edition to include deck slabs of both cast-in-place and precast construction, which are now referred to as “externally restrained deck slabs”, whereas deck slabs containing internal FRP reinforcement are referred to as “internally restrained deck slabs”. The resistance factors of the previous edition have been revised and depend on conditions of use, with a further distinction made between factory- and field-produced FRPs. The previous edition’s deformability requirements for FRP-reinforced and FRP-prestressed concrete beams and slabs are now dealt with in separate clauses that cover design for deformability, minimum flexural resistance, and crack control reinforcement. The effect of the sustained loads on the strength of FRPs is accounted for in this edition by limits on stresses in FRPs induced at the serviceability limit state. In addition, new stress limits for tendons have been introduced. The design for shear is now an adaptation of this Code’s method for concrete structures and accounts for the decrease in shear carried by the concrete in FRP-reinforced beams. There are also modified provisions for barrier walls. Funding for developing and publishing this Code was provided by the governments of Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, the Northwest Territories, Nova Scotia, Nunavut, Ontario, Prince Edward Island, Québec, Saskatchewan, and Yukon, Public Works and Government Services Canada, and the Federal Bridge Corporation Limited. This Code could not have been developed without the cooperation of all of these sponsors. This Code was prepared by the Technical Committee on the Canadian Highway Bridge Design Code, under the jurisdiction of the Strategic Steering Committee on Structures (Design), and has been formally approved by the Technical Committee. It has been approved as a National Standard of Canada by the Standards Council of Canada. November 2006 Notes: (1) Use of the singular does not exclude the plural (and vice versa) when the sense allows. (2) Although the intended primary application of this Code is stated in Clause 1.1.1, it is important to note that it remains the responsibility of the users of the Code to judge its suitability for their particular purpose. (3) This publication was developed by consensus, which is defined by CSA Policy governing standardization — Code of good practice for standardization as “substantial agreement. Consensus implies much more than a simple majority, but not necessarily unanimity”. It is consistent with this definition that a member may be included in the Technical Committee list and yet not be in full agreement with all clauses of this publication. (4) CSA Codes and Standards are subject to periodic review, and suggestions for their improvement will be referred to the appropriate committee. (5) All enquiries regarding this Code, including requests for interpretation, should be addressed to Canadian Standards Association, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6. Requests for interpretation should (a) define the problem, making reference to the specific clause, and, where appropriate, include an illustrative sketch; (b) provide an explanation of circumstances surrounding the actual field condition; and (c) be phrased where possible to permit a specific “yes” or “no” answer. Committee interpretations are processed in accordance with the CSA Directives and guidelines governing standardization and are published in CSA’s periodical Info Update, which is available on the CSA Web site at www.csa.ca.

May 2010

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Foreword In Canada, the legal mandate for establishing design and construction requirements for highways, including highway bridges, lies with the provincial and territorial governments. Before the publication of the previous edition of this Code, Ontario regulated the design and construction of highway bridges through the Ontario Highway Bridge Design Code. All of the other provinces and territories used CAN/CSA-S6, Design of Highway Bridges, with the exception of Manitoba, which adopted the bridge code published by the American Association of State Highway and Transportation Officials (AASHTO). The previous edition of the Canadian Highway Bridge Design Code was developed to provide a state-of-the-art model design code that could be adopted by all provinces and territories. This new edition is intended to serve the same purpose. Among the benefits associated with undertaking the development of this Code is the opportunity to establish safety and reliability levels for highway bridges that are consistent across all Canadian jurisdictions. Adoption of a single code makes it easier for the consulting and producer industries to respond to calls for proposals and eliminates the need for familiarity with the details of several codes. The adoption of a single code also supports the implementation of a national highway transportation system with agreed minimum standards and loadings for bridges on interprovincial highways, thereby encouraging consistency of vehicle weights across jurisdictions and supporting the objective of more cost-effective transportation of goods. Designers need to be aware, however, that although this Code establishes CL-625 loading as the minimum for bridges that are part of the national highway system, it is within the mandate of the provinces and territories to adopt a heavier or lighter live loading based on local traffic conditions. For example, Ontario requires (as specified in Annex A3.4) the use of a CL-625-ONT loading in the design of new bridges; this reflects the higher average regulatory and observed loads for trucks operating in the province. All of the requirements of this Code applicable to CL-W loading also apply to CL-625-ONT loading. Designers should always obtain approval from the regulatory authority when a live loading other than the CL-625 loading is to be used for design, and should check whether any variations from the requirements of this Code are in effect in the jurisdiction, e.g., for evaluation of existing bridges or issuance of overload permits. This Code was developed by taking into account the different regulatory structures and standards of Canada’s provinces and territories. Overall priorities and objectives were established by the Regulatory Authority Committee (RAC), which also monitored the progress of the Code’s development. In accordance with CSA procedural requirements, however, responsibility for the technical content of this Code was assigned to the Technical Committee (TC), as were decisions on how to deal with the priorities and objectives identified by the RAC. Because of the breadth and complexity of this Code, subcommittees (which were required to operate and report on a consensus basis) were established to oversee each section. In addition, task forces were established to handle specific aspects of this Code. The subcommittees and task forces reported to the TC through their Chairs. The extensive use of subcommittees permitted the recruitment of experts with the knowledge needed to address the sometimes highly specialized subjects covered by this Code. The developers of this Code wish to acknowledge the contributions of the following individuals, who were unable to complete their terms on the RAC and TC: Ismail Elkholy (RAC and former Vice-Chair of TC) (Manitoba Department of Highways and Transportation) and Peter Lester (RAC and TC) (Newfoundland and Labrador Department of Transportation and Works). This Code is complemented by CSA S6.1-06, Commentary on CAN/CSA-S6-06, Canadian Highway Bridge Design Code, which provides rationale statements and explanatory material for many of the clauses of this Code. Although this Code is being published in both English and French, CSA S6.1 is available only in English.

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Section 1 — General 1.1 1.1.1 1.1.2 1.1.3 1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.4 1.4.1 1.4.2 1.4.3 1.4.4 1.5 1.5.1 1.5.2 1.6 1.6.1 1.6.2 1.6.3 1.6.4 1.7 1.7.1 1.7.2 1.7.3 1.8 1.8.1 1.8.2 1.8.3 1.9 1.9.1 1.9.2 1.9.3 1.9.4 1.9.5 1.9.6 1.9.7 1.9.8 1.9.9 1.9.10 1.9.11

Scope 2 Scope of Code 2 Scope of this Section 2 Terminology 2 Reference publications 2 Definitions 10A General 10A General administrative definitions 10A General technical definitions 10B Hydraulic definitions 15 General requirements 16 Approval 16 Design 17 Evaluation and rehabilitation of existing bridges 18 Construction 18 Geometry 20 Planning 20 Structure geometry 20 Barriers 20 Superstructure barriers 20 Roadside substructure barriers 20 Structure protection in waterways 21 Structure protection at railways 21 Auxiliary components 21 Expansion joints and bearings 21 Approach slabs 21 Utilities on bridges 21 Durability and maintenance 22 Durability and protection 22 Bridge deck drainage 22 Maintenance 24 Hydraulic design 25 Design criteria 25 Investigations 26 Location and alignment 26 Estimation of scour 26 Protection against scour 27 Backwater 29 Soffit elevation 29 Approach grade elevation 30 Channel erosion control 30 Stream stabilization works and realignment 31 Culverts 31

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Section 1 General 1.1 Scope 1.1.1 Scope of Code This Code applies to the design, evaluation, and structural rehabilitation design of fixed and movable highway bridges in Canada. There is no limit on span length, but this Code does not necessarily cover all aspects of design for every type of long-span bridge. This Code also covers the design of pedestrian bridges, retaining walls, barriers, and highway accessory supports of a structural nature, e.g., lighting poles and sign support structures. This Code is not intended to apply to public utility structures or to bridges used solely for railway or rail transit purposes. This Code also does not specify requirements related to coastal effects (e.g., exposure to sea action and icebergs) or to mountainous terrain effects (e.g., avalanches). For structures that can be subject to such effects, specialists need to be retained to review and advise on the design and to ensure that the applicable requirements of other codes are met. For bridges not entirely within the scope of this Code, the requirements of this Code apply only when appropriate. Necessary additional or alternative design criteria are subject to Approval.

1.1.2 Scope of this Section This Section specifies requirements for applying the Code and requirements of a general nature for bridges, culverts, and related works. These requirements govern basic geometry and hydraulic design. General requirements are also specified for subsidiary components, deck drainage, maintenance, and inspection access. Broad guidelines related to economic, aesthetic, and environmental considerations are also provided.

1.1.3 Terminology In CSA Standards, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; “should” is used to express a recommendation or that which is advised but not required; “may” is used to express an option or that which is permissible within the limits of the standard; and “can” is used to express possibility or capability. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

1.2 Reference publications This Code refers to the following publications, and where such reference is made, it shall be to the edition listed below, including all amendments published thereto. 

CSA (Canadian Standards Association) CAN/CSA-A23.1-09/CAN/CSA-A23.2-09 Concrete materials and methods of concrete construction/Methods of test and standard practices for concrete

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

CAN/CSA-A23.4-00/CAN/CSA-A251-00 Precast concrete — Materials and construction/Qualification code for architectural and structural precast concrete products CAN/CSA-A257 Series-03 Standards for concrete pipe and manhole sections CAN/CSA-A257.1-03 Non-reinforced circular concrete culvert, storm drain, sewer pipe, and fittings CAN/CSA-A257.2-03 Reinforced circular concrete culvert, storm drain, sewer pipe, and fittings CAN/CSA-A257.3-03 Joints for circular concrete sewer and culvert pipe, manhole sections, and fittings using rubber gaskets B95-1962 (R2002) Surface texture (roughness, waviness and lay) B97.3-M1982 (R2002) Tolerances and standard fits for mating parts, metric sizes B111-1974 (R2003) Wire nails, spikes and staples C22.1-09 Canadian Electrical Code, Part I C22.2 No. 100-04 Motors and generators C22.2 No. 178-1978 (R2001) Automatic transfer switches CAN/CSA-C22.3 No. 1-01 Overhead systems G4-00 Steel wire rope for general purpose and for mine hoisting and mine haulage G30.3-M1983 (withdrawn) Cold-drawn steel wire for concrete reinforcement G30.5-M1983 (withdrawn) Welded steel wire fabric for concrete reinforcement G30.14-M1983 (withdrawn) Deformed steel wire for concrete reinforcement G30.15-M1983 (withdrawn) Welded deformed steel wire fabric for concrete reinforcement CAN/CSA-G30.18-M92 (R2002) Billet-steel bars for concrete reinforcement

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G40.20-04/G40.21-04 (R2009) General requirements for rolled or welded structural quality steel/Structural quality steel

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CAN/CSA-G164-M92 (withdrawn) Hot dip galvanizing of irregularly shaped articles

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G189-1966 (withdrawn) Sprayed metal coatings for atmospheric corrosion protection G279-M1982 (withdrawn) Steel for prestressed concrete tendons

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G401-07 Corrugated steel pipe products

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O56-10 Round wood piles

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CAN/CSA-O80 Series-08 Wood preservation

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CAN/CSA-O80.3-97 Preservative treatment of piles by pressure processes O80.9-97 Preservative treatment of plywood by pressure processes

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CAN/CSA-O86-09 Engineering design in wood

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CAN/CSA-O122-06 Structural glued-laminated timber

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O141-05 (R2009) Softwood lumber O177-06 Qualification code for manufacturers of structural glued-laminated timber S6.1-06 Commentary on CAN/CSA-S6-06, Canadian Highway Bridge Design Code

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CAN/CSA-S16-09 Design of steel structures

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CAN/CSA-S157-05/S157.1-05 (R2010) Strength design in aluminum/Commentary on CSA S157-05, Strength design in aluminum

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S269.1-1975 (withdrawn) Falsework for construction purposes

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CAN/CSA-S269.2-M87 (withdrawn) Access scaffolding for construction purposes

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CAN/CSA-S806-02 (R2007) Design and construction of building components with fibre-reinforced polymers

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W47.1-09 Certification of companies for fusion welding of steel

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W47.2-M1987 (R2009) Certification of companies for fusion welding of aluminum

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CAN/CSA-W48-06 Filler materials and allied materials for metal arc welding

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W59-03 (R2008) Welded steel construction (metal arc welding)

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W59.2-M1991 (R2008) Welded aluminum construction

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W178.2-08 Certification of welding inspectors

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W186-M1990 (R2007) Welding of reinforcing bars in reinforced concrete construction

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AA (Aluminum Association) ADM-1 (2010) Aluminum Design Manual

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AASHTO (American Association of State Highway and Transportation Officials) GSBR (1989) (withdrawn) Guide Specifications for Bridge Railings GVCB-1 (1991) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges HB-17 (2002) Standard Specifications for Highway Bridges, 17th ed.

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LRFD-US-3 (2007) LRFD Bridge Design Specification, 4th ed. ANSI/NEMA (American National Standards Institute/National Electrical Manufacturers Association) MG-1-2003 Motors and generators AREMA (American Railway Engineering and Maintenance of Way Association) Manual for Railway Engineering, 4th ed. (2005) ASCE (American Society of Civil Engineers) 15-98 Standard Practice for Direct Design of Buried Precast Concrete Pipe Using Standard Installations (SIDD)

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ASME International (American Society of Mechanical Engineers) B1.10M-2004 (R2009) Unified Miniature Screw Threads B4.1-1967 (R2009) Preferred Limits and Fits for Cylindrical Parts

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B17.1-1967 (R2008) Keys and Keyseats

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B18.3-2003 (R2008) Socket Cap, Shoulder, and Set Screws, Hex and Spline Keys (Inch Series)

© Canadian Standards Association

ASTM International (American Society for Testing and Materials) A 27/A 27M-05 Standard Specification for Steel Castings, Carbon, for General Application A 36/A 36M-05 Standard Specification for Carbon Structural Steel A 48/A 48M-03 Standard Specification for Gray Iron Castings A 53/A 53M-04a Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless A 108-03 e1 Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished A 148/148M-05 Standard Specification for Steel Castings, High Strength, for Structural Purposes A 153/A 153M-05 Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware A167-99 (2004) Standard Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip A 240/A 240M-05 Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications A 276-05 Standard Specification for Stainless Steel Bars and Shapes A 307-04 Standard Specification for Carbon Steel Bolts and Studs, 60 000 PSI Tensile Strength A 325-04b Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength A 325M-04b Standard Specification for Structural Bolts, Steel, Heat Treated 830 MPa Minimum Tensile Strength [Metric] 

A325M-05 Standard Specification for Structural Bolts, Steel, Heat Treated 830 MPa Minimum Tensile Strength [Metric] A 370-05 Standard Test Methods and Definitions for Mechanical Testing of Steel Products A 449-04b Standard Specification for Quenched and Tempered Steel Bolts and Studs

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A 486/A 486M-84 (withdrawn Standard) Specification for Steel Castings for Highway Bridges A 490-04a Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength A 490M-04a Standard Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural Steel Joints [Metric] A 510-03 Standard Specification for General Requirements for Wire Rods and Coarse Round Wire, Carbon Steel A 586-04a Standard Specification for Zinc-Coated Parallel and Helical Steel Wire Structural Strand A 588/A 588M-05 Standard Specification for High-Strength Low-Alloy Structural Steel, up to 50 ksi [345 MPa] Minimum Yield Point, with Atmospheric Corrosion Resistance A 603-98 (R2003) Standard Specification for Zinc-Coated Steel Structural Wire Rope A 641/A 641M-03 Standard Specification for Zinc-Coated (Galvanized) Carbon Steel Wire A 653/A 653M-05 Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process A 668/A 668M-04 Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use A 675/A 675M-03 e1 Standard Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality, Mechanical Properties A 709/A 709M-05 Standard Specification for Carbon and High-Strength Low-Alloy Structural Steel Shapes, Plates, and Bars and Quenched-and-Tempered Alloy Structural Steel Plates for Bridges A 722/A 722M-07 Standard Specification for Uncoated High-Strength Steel Bars for Prestressing Concrete B 22-02 Standard Specification for Bronze Castings for Bridges and Turntables 

B 26/B 26M-09 Standard Specification for Aluminum-Alloy Sand Castings B 36/B 36M-01 Standard Specification for Brass Plate, Sheet, Strip, and Rolled Bar

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B 108/B 108M-08 Standard Specification for Aluminum-Alloy Permanent Mold Castings B 121/B 121M-01 Standard Specification for Leaded Brass Plate, Sheet, Strip, and Rolled Bar

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B 209-07 Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate October 2011 (Replaces p. 7, May 2010)

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B 211-03 Standard Specification for Aluminum and Aluminum-Alloy Bar, Rod, and Wire

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B 221-08 Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes

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B 308/B 308M-10 Standard Specification for Aluminum-Alloy 6061-T6 Standard Structural Profiles

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B 429/B 429M-10 Standard Specification for Aluminum-Alloy Extruded Structural Pipe and Tube B 746/B 746M-02 Standard Specification for Corrugated Aluminum Alloy Structural Plate for Field-Bolted Pipe, Pipe-Arches, and Arches

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B 928/B 928M-09 Standard Specification for High Magnesium Aluminum-Alloy Sheet and Plate for Marine Service and Similar Environments C 78-09 Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading) C 506M-05 Standard Specification for Reinforced Concrete Arch Culvert, Storm Drain, and Sewer Pipe [Metric] C 507M-05 Standard Specification for Reinforced Concrete Elliptical Culvert, Storm Drain, and Sewer Pipe [Metric] C 567-05 Standard Test Method for Determining Density of Structural Lightweight Concrete C 1399-07 Standard Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete C 1433-04 e1 Standard Specification for Precast Reinforced Concrete Box Sections for Culverts, Storm Drains, and Sewers [Metric] D 395-03 Standard Test Methods for Rubber Property — Compression Set D 412-98a (2002) e1 Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers — Tension D 429-03 Standard Test Methods for Rubber Property — Adhesion to Rigid Substrates D 573-04 Standard Test Method for Rubber — Deterioration in an Air Oven D 698-00 ae1 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)) D 746-04 Standard Test Method for Brittleness Temperature of Plastics and Elastomers by Impact

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D 1149-99 Standard Test Method for Rubber Deterioration-Surface Ozone Cracking in a Chamber D 1557-02 e1 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)) D 2239-03 Standard Specification for Polyethylene (PE) Plastic Pipe (SIDR-PR) Based on Controlled Inside Diameter D 2240-04 e1 Standard Test Method for Rubber Property — Durometer Hardness D 2487-00 Standard Classification of Soils for Engineering Purposes (Unified Soil Classification System) D 3350-04 Standard Specification for Polyethylene Plastics Pipe and Fittings Materials D 4541-02 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers D 4894-04 Standard Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion Materials D 5456-05 Standard Specification for Evaluation of Structural Composite Lumber Products 

E 290-09 Standard Test Methods for Bend Testing of Material for Ductility

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E 561-98-02 Standard Practice for R-curve Determination F 436-04 Standard Specification for Hardened Steel Washers

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F 467-08e1 Standard Specification for Nonferrous Nuts for General Use

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F 468-10 Standard Specification for Nonferrous Bolts, Hex Cap Screws, and Studs for General Use

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F 563-00 (withdrawn) Standard Specification for Wrought Cobalt 20Nickel 20Chromium 3.5Molybdenum 3.5Tungsten 5Iron Alloy for Surgical Implant Applications (UNS R30563) F 568M-04 Standard Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners

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F 593-02(2008) Standard Specification for Stainless Steel Bolts, Hex Cap Screws, and Studs

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F 594-09e1 Standard Specification for Stainless Steel Nuts

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F 1852-08 Standard Specification for “Twist Off” Type Tension Control Structural Bolt/Nut/Washer Assemblies, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength F 2280-08 Standard Specification for “Twist Off” Type Tension Control Structural Bolt/Nut/Washer Assemblies, Steel, Heat Treated 150 ksi Minimum Tensile Strength PS 62-97 (withdrawn Provisional Standard) Provisional Standard Specification for Precast Reinforced Concrete Box Sections for Culverts, Storm Drains, and Sewers AWPA (American Wood-Preservers’ Association) C33-03 Standard for Preservative Treatment of Structural Composite Lumber by Pressure Processes 

AWS (American Welding Society) A5.10/A5.10M:1999 Specification for Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods D1.2/D1.2M:2008 Structural Welding Code — Aluminum D17.3/D17.3M:2010 Specification for Friction Stir Welding of Aluminum Alloys for Aerospace Applications

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BSI (British Standard Institution) BS5400-3:2000 Steel, Concrete and Composite Bridges

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CEN (European Committee for Standardization) Eurocode 9:2006 Design of Aluminum Structures

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ECCS (European Convention for Constructions Steelwork) European Recommendation for Aluminum Alloy Structures, 1992 ed. Government of Canada Navigable Waters Protection Act, RSC 1985, c. N-22 NCHRP (National Cooperative Highway Research Program) Report 230 (1980) Recommended Procedures for the Safety Performance Evaluation of Highway Appurtenances Report 350 (1993) Recommended Procedures for the Safety Performance Evaluation of Highway Features NEMA (National Electrical Manufacturers Association) ICS9-1993 (withdrawn Standard) Industrial Control and Systems: Power Circuit Accessories NLGA (National Lumber Grades Authority) Standard Grading Rules for Canadian Lumber (2003)

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NRCC (National Research Council Canada) National Building Code of Canada, 2005 National Fire Code of Canada, 2005 Research Council on Structural Connections Specification for Structural Joints Using ASTM A325 or A490 Bolts (2004) Transportation Association of Canada Geometric Design Guide for Canadian Roads (1999) Guide to Bridge Hydraulics, 2nd ed. (2001) Manual of Uniform Traffic Control Devices for Canada (1998) UL (Underwriters Laboratories Inc.) 845 (1995) Standard for Motor Control Centers U.S. Department of Defense MIL-S-8660C (1999) (cancelled Specification) Silicone Compound

1.3 Definitions 1.3.1 General The definitions in Clauses 1.3.2 to 1.3.4 apply in this Code. Note: Additional definitions are found in Sections 2 to 16. In the case of a conflict between a definition in Sections 2 to 16 and a definition in Clauses 1.3.2 to 1.3.4, the definition in Sections 2 to 16 takes precedence.

1.3.2 General administrative definitions Note: The general administrative terms defined in this Clause are capitalized wherever they are used in this Code in their defined sense.

Approval or Approved — approval, or approved, in writing by the Regulatory Authority. Checker — a member or licensee of the Engineering Association who carries out the design check, rehabilitation design check, or evaluation check of a bridge or structure. Construction — the construction, reconstruction, rehabilitation, repair, or demolition of a structure. Constructor — (a) a Person that contracts to perform all of the Construction work on a project; (b) an Owner that contracts with two or more Persons for such Persons to perform part of the Construction work on a project; or (c) an Owner that performs all or part of the Construction work on a project. Engineer — a member or licensee of the Engineering Association who carries out the design, rehabilitation design, or evaluation of a bridge or structure. Engineering Association — an organization authorized by charter to regulate the profession of engineering in a province or territory. Owner — the Person having responsibility for and control of a bridge or structure.

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Person — an individual, board, commission, partnership, or corporation (including a municipal corporation) and his, her, or its agents, successors, and assignees. Plans — the drawings, documents, and specifications that define a Construction project, form part of the contract documents, or are included in the contract documents by reference; all Approved drawings and descriptions produced by a Constructor for the Construction of a bridge or other structure; and all revisions to the items described in this definition. Regulatory Authority — the federal, provincial, or territorial Minister having governmental jurisdiction and control, his or her nominee, or the local authority to whom this authority is delegated.

1.3.3 General technical definitions Abutment — a substructure that supports the end of a superstructure and retains some or all of the bridge approach fill. Arterial road — an arterial road as defined in the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Auxiliary component — a component of a structural system that does not constitute part of the intended load-sharing system. Auxiliary components include expansion joints, approach slabs, railings and barriers, and deck drains. Average annual daily traffic — the total volume of traffic during a year divided by the number of days in the year.

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Average daily traffic — the total volume of traffic during a given time period, in whole days, greater than one day and less than one year, divided by the number of days in that time period. Average daily truck traffic — the total volume of truck traffic during a given time period, in whole days, greater than one day and less than one year, divided by the number of days in that time period. Ballast wall — that part of an abutment above the bearing seats used primarily to retain approach fill and to provide a support for an approach slab and expansion joint. Barrier — a wall, railing, or fence that serves as a vehicular, pedestrian, bicycle, or combination barrier or as a noise or privacy barrier. Barrier wall — a barrier that has no openings and is at least 800 mm high. Bearing — a structural device that transmits loads while facilitating translation or rotation. Bevelled end — a culvert end cut or formed to lie in a plane inclined to the vertical. Bicycle barrier — a barrier for confining cyclists. Box culvert — a closed-invert culvert with a monolithic rectangular or trapezoidal cross-section. Bridge — a structure that provides a roadway or walkway for the passage of vehicles, pedestrians, or cyclists across an obstruction, gap, or facility and is greater than 3 m in span. Clear recovery zone — a roadside area that can be safely used by errant vehicles, is immediately adjacent to the edge of a traffic lane, and is clear of hazards. Coated reinforcement — steel reinforcement that is used in concrete and is coated with a protective coating complying with the requirements of Section 8. Collapse — a major change in the geometry of a structure rendering it unfit for use. Collector — a collector road as defined in the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Combination barrier — a barrier that serves as a vehicular barrier and as a pedestrian or bicycle barrier. Component — a member of a structure requiring individual design consideration. Crossfall — the transverse slope of a roadway, sidewalk, or deck surface. Crown — Crown of a bridge or culvert — the highest point on a curved soffit. Crown of a roadway — the highest point of a cross-section, formed where opposite crossfalls meet. Culvert — a structure that forms an opening through soil. Curb — a raised surface beside a roadway, forming a vertical or nearly vertical face that delineates the roadway edge and in some cases also channels water. Cut-off wall — a vertical wall attached to and extending below the end of a culvert or other structure. Deck — a component of a bridge superstructure that carries and distributes wheel loads. Deck joint — a structural discontinuity between two components, at least one of which is a deck component, that permits relative rotation or translation between the two.

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Deck slab — a solid concrete slab that carries and distributes loads to supporting members. Deck width — the horizontal distance, measured at deck level perpendicular to the direction of travel, from face to face of sidewalks or curbs (or barrier walls if there are no curbs). Design — the process of planning, analyzing, proportioning, drawing, and writing specifications for the Construction of a structure. Design lane — a longitudinal strip that is a fraction of the deck width, within which a truck or lane load is placed for the purpose of design or evaluation. Design life — a period of time, specified by an Owner, during which a structure is intended to remain in service. Divided highway — a highway with two or more roadways separated by medians or barriers. Downpipe — a pipe for conveying water from a deck drain to the ground or to a storm sewer. Downspout — a short pipe extending from a deck drain to below the bridge superstructure. Drip groove — a groove formed in a surface and intended to cause water to drop off the surface rather than run along it. Ductility — the ability to deform without failing after yielding. Evaluation — the process of determining load-carrying capacity. Expressway — an expressway as defined in the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Factored resistance — the resistance of a component, connection, foundation, or cross-section calculated in accordance with the requirements and assumptions of this Code, including the application of appropriate resistance factors. Failure — a state in which rupture, severe distortion or displacement, or loss of strength has occurred as a result of the load-carrying capacity of a component or connection having been exceeded. Falsework — a temporary structure that is used to support another structure or a part thereof, usually during a particular Construction procedure or sequence. Fascia — the surface that forms the lateral limit of a bridge. Fatigue — the initiation or propagation of cracks caused by the repeated application of load. Fatigue limit state — a limit state at which the effects of fatigue on the strength or condition of a structure are considered. Floor beam — a transverse beam spanning between longitudinal girders, trusses, or arches. Freeway — a freeway as defined in the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Gabion — a wire mesh basket that is filled with stone or broken rock or concrete and forms part of a larger unit used for slope stability, erosion control, or related purposes. Girder — a longitudinal beam resting directly on the substructure. Guiderail — a rail system along the edge of a roadway to delineate the roadway edge and to help redirect errant vehicles.

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Hazard — any obstacle or other feature, e.g., an embankment, sideslope, or body of water deeper than 1 m, that, without protection, is likely to cause significant injury to the occupants of a vehicle striking it. Headwall — a transverse wall at the end of a culvert. Highway — a common and public thoroughfare, e.g., a road, street, avenue, parkway, driveway, square, place, bridge, culvert, viaduct, or trestle, designed and intended for, or used by the general public for, the passage of pedestrians, cyclists, animals, or vehicles. Highway class — the class of highway determined in accordance with the volume of vehicular and truck traffic (see Clause 1.4.2.2). Highway classification — a category of highway, i.e., freeway, arterial road, collector road, or local road, that is used in establishing criteria for the geometric design of bridges. Interface shear — shear at and in the plane of an interface between (a) dissimilar elements or materials, e.g., a deck slab and a beam, or a web and a flange; or (b) concrete cast at different times. Lane — a traffic lane. Limit states — those conditions beyond which a structure or component ceases to meet the criteria for which it was designed. Load effect — any effect on or response of a structural component due to loads, forces, imposed deformations, or volumetric changes. Load factor — a factor applied to loads to take into account variability of loads, lack of precision in analysis for load effects, and reduced probability of loads from different sources acting simultaneously. Local road — a local road as defined in the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Longitudinal — the lengthwise direction. For bridges, this is normally the direction of traffic flow on the deck and of the main span. For culverts, it is normally the direction of the culvert axis. Long-span bridge — a bridge with an individual span longer than 150 m. Median — a raised or marked area that separates the roadways of a divided highway. Member — an element or assembly of elements within a structure that performs an identifiable function and can require individual design consideration. Multiple-load-path structure — a system of components in which the failure of any primary component or connection will not cause the structure to collapse. Open-type abutment — an abutment in front of which is a slope extending downward from a point on the abutment face that is just below the superstructure. Orthotropic deck — a deck that is orthogonally anisotropic. Normally this is a deck made of steel plate stiffened with open or closed steel ribs welded to the underside of the steel plate. Pedestrian barrier — a barrier that is intended to confine pedestrians. Pedestrian bridge — a bridge that provides a walkway primarily for the passage of pedestrians. Pier — a substructure used to transfer superstructure loads from the spans it supports to the foundation.

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Primary component — a component of a structural system that performs an essential role in load transfer and, on becoming ineffective, will substantially reduce the load-carrying capacity of the system or cause the collapse of a single-load-path structure. Rehabilitation — a modification, alteration, or improvement of the condition of a structure or bridge subsystem that is designed to correct deficiencies in order to achieve a particular design life and live load level. Reliability index or safety index — a numerical measure of the reliability of structures or components. Resistance factor — a factor applied to the unfactored resistance of a component or material at the ultimate limit state to take into account the variability of material properties and dimensions, quality of work, type of failure, and uncertainty in the prediction of the resistance. Return period — the average period in years between the occurrence of an event (e.g., a flood) and the next occurrence of an event of the same type. Roadway — that part of a highway that is intended for or can be used by vehicles, including traffic lanes, shoulders, and other adjacent areas such as those provided for clearance, pedestrians, or bicycles, if these areas are not separated by a barrier, by a guiderail, or by a curb that is at least 150 mm high. Secondary component — a component of a structural system that does not have an essential role in load transfer and whose removal from the structure would result in at most a minor redistribution of load effects to adjacent components. Serviceability limit state — the limit state at which the effects of vibration, permanent deformation, and cracking on the usability or condition of a structure are considered. Sidewalk — a pedestrian walkway located beside a roadway. Single-load-path structure — a structure in which the failure of any primary component or connection will cause the structure to collapse. Skew angle — the angle by which a bridge differs from a right-angled crossing. Normally, this is the angle between the longitudinal centreline of the bridge and a line perpendicular to the centreline of the bearings. Span — the following distances: (a) the horizontal distance between the centrelines of adjacent piers or abutments; (b) where bearings are provided, the horizontal distance between bearing centrelines; (c) for rigid frames, including box culverts, the clear opening width; and (d) a distance specified as a span in another Section of this Code. Spread footing — a footing that transfers structure loads directly to the underlying soil, rock, or engineered fill. Stress range — the algebraic difference between the maximum and minimum stress at the fatigue limit state where tension and compression are of opposite sign. Stringer — a longitudinal element supporting the deck and spanning between floor beams. Substructure — that part of a bridge, including abutments and piers, that supports the superstructure. Superstructure — that part of a bridge that spans water, a roadway, a railway, or another obstruction and is supported by the substructure. Temporary structure — a structure with a design life of less than five years. Traffic barrier — a barrier that is intended to confine vehicular traffic to a roadway or bridge deck.

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Traffic lane — a part of a roadway designated for the movement of a single file of vehicles. Transverse — in a plane that is perpendicular to the longitudinal direction. Ultimate limit state — a limit state that involves failure (including rupture, fracture, overturning, sliding, and other instability). Unfactored resistance — the resistance of a component or connection based on specified material properties and nominal dimensions and calculated in accordance with this Code. Utilities — transmission and distribution lines, pipes, cables, and other associated equipment used for public services including, but not limited to, electric power transmission and distribution, lighting, heating, gas, oil, water, sewage, cable television, telephone, and telegraph facilities. Vehicle — a motor vehicle, motor-assisted bicycle, trailer, traction engine, car, truck, farm tractor, road-building machine, or any device drawn or propelled by power other than that of the driver or operator, but not including the cars or engines of electric, diesel, or steam railways. Yield strength — the specified or established minimum yield strength of a material.

1.3.4 Hydraulic definitions Abnormal flood — a flood or flood condition produced at a site by abnormal events or conditions downstream or upstream of the site, including ice jams. Apron — an area of protective material laid on a stream bed to control local scour around a feature requiring protection. Backwater — the rise in water level caused by a downstream obstruction or constriction in a channel. Bridge waterway — that part of a bridge opening that is or can be occupied by water. Check flood — a flood greater than the normal design flood, used to check that a waterway designed for the normal design flood will withstand a larger flood without embankment failure or structural collapse. Collar — a concrete ring or stiffening component placed integrally with and at the end of a metal culvert. Competent velocity — the velocity at which water will begin to move material of a given type and particle size. Degradation — general and progressive lowering of the longitudinal profile of a channel by erosion. Depth of scour — the depth of material removed from a stream bed by scour, measured below the original bed. Design flood — a flood that a structure is designed to accommodate while conforming to specified requirements. Discharge — the rate of flow of water in cubic metres per second. Drop structure — a structure in a channel designed to lower the channel invert and the hydraulic grade line abruptly. Flood — an event leading to an above-normal water level or discharge. Flood plain — the relatively level area that adjoins a watercourse or other body of water and is subject to periodic flooding.

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General scour — scour in a stream bed that occurs at a structure as a result of general stream velocities exceeding the competent velocity of channel bed material. Improved inlet — a culvert inlet incorporating refined inlet geometry for the purpose of improving the culvert hydraulic capacity. Inerodible — durable enough to ensure that no important erosion will occur during the design life of the structure. Invert — the lowest point at a particular section of a channel bed or culvert opening. Local scour — scour in a stream bed adjacent to an obstruction, e.g., a pier or abutment, resulting from the disruption of flow caused by the obstruction. Normal design flood — the design flood that a structure is required to accommodate without damage to the structure or approaches. Normal water level — the average summer water level. Open-footing culvert — a culvert with individual wall foundations on either side of a stream bed or passageway. Original stream bed — the bed as it existed or exists before an actual or planned modification or activity. Piping — a movement of water through the soil around a structure that can cause loss of fine particles. Regulatory flood — a designated flood primarily used to define the limits of a flood plain for regulatory purposes. In special circumstances, it may be specified as the design flood to be used for particular purposes. Relief flow — the flood flow that bypasses the main structure opening at a stream or river crossing by flowing over the highway elsewhere or through a relief structure. Revetment — a vertical or inclined facing of rip-rap or other material protecting a soil surface from erosion. Scour — erosion of a stream bed by the action of flowing water. Stream bed — the surface of a natural or modified channel bed. Ultimate bed elevation — the anticipated lowest stream bed elevation occurring during the design life of a structure that allows for all scour and for degradation and artificial deepening.

1.4 General requirements 1.4.1 Approval Approval shall be obtained for any item, component, process, analytical method, or method of construction that does not comply with this Code or is outside Code limits. Use of load or strength formulations from other codes in conjunction with this Code shall require an Approved investigation of compatibility and comparative safety levels, with appropriate adjustment of load and resistance factors.

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1.4.2 Design 1.4.2.1 Design philosophy In the interpretation and application of this Code, the primary concern shall be the safety of the public, including that of Construction and maintenance workers. Design shall be based on the consideration of limit states in which, at the ultimate limit state, the factored resistance is used to exceed the total factored load effect. Structural components shall be designed to comply with the ultimate limit state, serviceability limit state, and fatigue limit state requirements of the applicable clauses of this Code. The Engineer shall ensure that all limit states appropriate to the particular structure being designed are investigated. In accordance with Section 5, and unless otherwise specified, elastic methods of analysis shall be required for determining structural behaviour and for determining responses of a structure and its components at all limit states. Inelastic methods and experimental methods of analysis of bridges shall require Approval unless specifically required or permitted by this Code.

1.4.2.2 Highway class The highway class shall be determined in accordance with Table 1.1 for the average daily traffic and average daily truck traffic volumes for which the structure is designed. Unless otherwise Approved, all new bridges shall be designed to comply with Class A highway requirements.

Table 1.1 Highway classes (See Clause 1.4.2.2.)

Highway class

Average daily traffic (ADT) per lane (number of vehicles)

Average daily truck traffic (ADTT) per lane (number of vehicles)

A

> 4000

> 1000

B

> 1000–4000

> 250–1000

C

100–1000

50–250

D

< 100

< 50

1.4.2.3 Design life Unless otherwise Approved, the design life of new structures shall be 75 years.

1.4.2.4 Structural behaviour and articulation All joints and bearings shall be designed as part of a system of articulation with appropriate anchorages, guides, restraints, and freedoms. Where bridges have superstructures that are supported by bearings on piers or abutments or some combination thereof, relative movements between the superstructure and substructure shall be analyzed and shall be allowed for in the design. The possible effects of the inexact fit of components shall be considered, with normal Construction and fabrication tolerances assumed unless tolerances are specified on the Plans. The effects of deflection on the magnitude and position of bearing reactions shall be considered, with allowance for the approximate nature of deflection calculations. Where relative movements are restrained or limited, the resulting force effects and distortions shall be considered.

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Unless otherwise Approved, superstructures with bearings and joints that electrically insulate them from the substructure and ground shall have direct ground connections to ensure that stray electrical and atmospheric electrostatic charges are harmlessly conducted to earth.

1.4.2.5 Single-load-path structures Special consideration shall be given to the critical components of single-load-path structures. Sufficient additional strength and protection shall be provided to ensure that they will not fail.

1.4.2.6 Economics After safety, the total projected lifetime cost shall be the determining consideration in selecting the type of structure, configuration of spans and supports, and Construction materials. This cost shall include allowances for inspection, maintenance, repair, and rehabilitation throughout the design life of the structure.

1.4.2.7 Environment Bridges, culverts, and their associated works shall be designed to comply with all environmental requirements established for the site. Wherever possible, features of archaeological, historical, and cultural importance shall be preserved. The design shall include an assessment of possible environmental effects and measures for limiting adverse effects to a practical minimum. Particular attention shall be paid to the preservation of wildlife and plant habitat. Structures on fish-bearing streams shall be designed to pass fish in accordance with Approved methods and criteria.

1.4.2.8 Aesthetics In the design and rehabilitation of structures, consideration shall be given to the appearance of the finished structure and to its compatibility with its surroundings. Wherever possible, the appearance of a structure shall be such that it will be generally perceived as an enhancement to its surroundings. Structures shall be simple and graceful in form, shall intrude minimally on desirable scenery, and shall exhibit an integrity in which the function of components is explicit in their form and their size realistically reflects necessary strength. Visual discontinuities or abrupt changes shall be avoided. Embellishments shall be permitted only where an important purpose is served and when the cost is demonstrably justified by the end served.

1.4.3 Evaluation and rehabilitation of existing bridges 1.4.3.1 Evaluation Requirements for the evaluation and load testing of highway bridges are specified in Section 14. The requirements of all other Sections shall be applied as appropriate unless specifically modified by Section 14.

1.4.3.2 Rehabilitation design Provisions for the rehabilitation design of highway bridges are specified in Section 15. The requirements of all other Sections shall be applied as appropriate unless specifically modified by Section 14 or 15.

1.4.4 Construction 1.4.4.1 General For the design of new bridges and therehabilitation design of existing bridges, the appropriate Sections of this Code shall apply to the consideration of all stages of Construction. In the evaluation of strength and stability for all stages, the following shall be considered: (a) the intended sequence of Construction; (b) the absence of restraints that would be present in the completed structure;

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(c) the possibility of loads or stresses in a member or component being temporarily greater than or of a reverse nature to those after completion; (d) construction loads; and (e) the consequences of failure.

1.4.4.2 Construction safety Protection for workers and the public at the construction site shall be in accordance with the applicable health and safety Acts and regulations. In the selection of construction methods and types of structures, the safety of construction workers shall be considered.

1.4.4.3 Construction methods When a bridge cannot be constructed without new or unusual procedures, or the assumed method of construction is not obvious, at least one method of construction shall be indicated on the Plans. When the method of Construction, rehabilitation, or demolition as envisaged by the Engineer is of such a nature as to cause critical load effects during Construction, the sequence of Construction stages and all necessary temporary support systems shall be shown on the Plans. The Plans shall indicate the location of all necessary temporary roadway and railway protection. The Plans shall require that when deviations from the indicated Construction methods are proposed, the Constructor shall submit new Plans to the Owner for Approval. The new Plans shall be signed and sealed in accordance with the requirements of the Regulatory Authority and indicate all proposed methods of Construction, sequences of Construction, and temporary support systems.

1.4.4.4 Temporary structures This Code shall apply to all temporary structures, except as follows: (a) CSA S269.1 and CAN/CSA-S269.2 shall apply to the design of falsework and temporary access scaffolding. (b) The requirements of the Regulatory Authority shall apply in lieu of this Code’s requirements for durability and serviceability. (c) This Code shall not apply to temporary traffic barrier installations. Except where otherwise Approved, falsework and temporary access scaffolding plans shall be designed by an Engineer and independently checked.

1.4.4.5 Plans The Plans shall specify all necessary details of the bridge or structure, the material requirements, the classification of the highway, the design live load, the rehabilitation level (where applicable), and the year of publication and edition number of the edition of this Code used. The system of articulation shall be shown on the Plans, including the location and type of bearings. Jacking locations shall be shown as required by Clause 1.8.3.3. Signing and sealing of drawings shall be performed in accordance with the requirements of the Regulatory Authority. The Plans shall include Approved specifications that are detailed and comprehensive enough to ensure that Construction is carried out in the manner and to the standards assumed in design and implicit in this Code. The requirements of this Code directly requiring the compliance of the Constructor shall be incorporated into the specifications.

1.4.4.6 Quality control and assurance Contractual requirements, Construction supervision, inspection, and testing shall be such as to ensure compliance with the Plans.

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1.5 Geometry 1.5.1 Planning The much greater cost and increased difficulty of widening bridges as compared to roadways shall be considered in determining whether the bridge cross-section should suit that of the proposed roadway or that planned for the roadway at some time in the future. Site conditions and requirements shall be considered in developing bridge alignment and plan geometry to accommodate existing and future traffic. The design average annual daily traffic, design hourly volume, and directional split shall be those forecast for a period starting not less than ten years after the design life start. For structures that are not easily widened, a longer period shall be determined from an economic assessment. Preference shall be given to straight horizontal alignments for bridges. The bridge deck longitudinal profile shall be continuous with the approach road profile.

1.5.2 Structure geometry 1.5.2.1 General Roadway and sidewalk widths, curb widths and heights, and all other geometrical requirements not specified in this Code shall comply with the standards of the Regulatory Authority or, in their absence, with the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Sidewalks and bicycle paths shall be separated from traffic lanes by a barrier or guiderail, or by a curb with a face height of at least 150 mm and a face slope not flatter than 1 horizontal to 3 vertical. Sidewalks and bicycle paths not so separated shall be designed as part of the roadway.

1.5.2.2 Clearances 1.5.2.2.1 Roadways and sidewalks Roadway and sidewalk clearances for structure openings and on structures shall comply with the standards of the Regulatory Authority or, in their absence, with the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads.

1.5.2.2.2 Railways Clearances for railways shall comply with the regulations of Transport Canada.

1.5.2.2.3 Waterways Clearances for navigable waterways shall comply with Clause 1.9.7.1.

1.5.2.2.4 Construction Clearances during Construction shall comply with the requirements of the agency with jurisdiction over the roadway, railway, or waterway passing through the opening.

1.6 Barriers 1.6.1 Superstructure barriers The design of permanent barriers on structures shall comply with Section 12.

1.6.2 Roadside substructure barriers Vehicular barriers or guiderails shall be provided in compliance with applicable roadside design requirements when the horizontal clearance from the roadway edge to a structure component is less than

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the clear recovery zone width determined in accordance with the requirements of the Regulatory Authority or, in their absence, with the Transportation Association of Canada’s Geometric Design Guide for Canadian Roads. Where a barrier is installed to protect a structural component, a minimum clearance of 125 mm shall be provided between the barrier and the component. For flexible guiderails, the clearance shall be sufficient to allow for their deflection under impact. For barriers that are designed as an integral part of the structural component, no clearance shall be required.

1.6.3 Structure protection in waterways If the waterway allows passage of vessels large enough to cause damage to the structure, independent, self-supporting fendering shall be provided to protect the structure and minimize damage to vessels. The fendering or the structure shall be designed to resist the vessel collision load in compliance with Section 3.

1.6.4 Structure protection at railways Protection shall be provided when specified by the railway authority.

1.7 Auxiliary components 1.7.1 Expansion joints and bearings Expansion joints and bearings shall comply with Section 11.

1.7.2 Approach slabs Unless otherwise Approved, bridges on paved roadways shall be provided with 6.0 m long reinforced concrete approach slabs anchored to the abutments. The approach slabs shall extend transversely to the limits of the roadway. The joints around the approach slabs shall be sealed.

1.7.3 Utilities on bridges 1.7.3.1 General Utilities on bridges shall be corrosion resistant and designed not to cause corrosion or staining of the structure.

1.7.3.2 Location and attachment Unless otherwise Approved, utilities on bridges shall be located in or under the side and median areas. In voided decks and box girders, utilities shall not pass through voids unless the voids are accessible for inspection and maintenance. Utilities shall be located and attached in such a manner that all primary components remain accessible. Utilities and fittings shall not be attached to primary components in such a manner as to adversely affect them structurally or reduce durability. Utility attachments to the flanges of steel girders shall not be permitted. All utilities on a bridge shall be designed for relocation to allow for future bridge maintenance. Conduits embedded in concrete shall follow the deck alignment where possible. Drains shall be provided at all low points. At transition joints, e.g., expansion joints, couplings shall be provided that will allow all possible movements without damage. At transition joints over or near structural bearings, the differential vertical movement allowance provided for jacking shall not be less than 15 mm.

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1.7.3.3 Highway utilities The original bridge design shall provide for a highway illumination power supply, lighting standards, remote sensing cabling, and any other utilities likely to be necessary.

1.7.3.4 Public utilities Provision shall be made for incorporating conduit in the superstructure for existing and planned utility cables that need to be carried across the structure.

1.7.3.5 Fluid-carrying utilities Utilities that carry fluids, including gas and oil lines, sewers, and water pipes, shall not be allowed in or under the superstructure or on the bridge unless Approved.

1.8 Durability and maintenance 1.8.1 Durability and protection Requirements for the durability of structures and for protective measures for structures (to ensure that the required design life is achieved) are specified in Section 2.

1.8.2 Bridge deck drainage 1.8.2.1 General Bridge deck drainage shall be designed to remove water from the deck as completely and quickly as possible and to discharge the runoff harmlessly.

1.8.2.2 Deck surface 1.8.2.2.1 Crossfall and grades Bridge deck drainage of the roadway shall be achieved by providing a minimum 2% transverse crossfall and by providing a minimum longitudinal grade of 0.5%, except where, for limited lengths, vertical curves or superelevation transitions preclude this. Except where unavoidable, bridges shall be located away from the low point of a sag curve in the vertical alignment of the road profile.

1.8.2.2.2 Deck finish Deck finishing methods and acceptance criteria shall be specified on the Plans, preclude the occurrence of local depressions in the surface of the concrete, and ensure a surface acceptable either for the application of a waterproofing membrane or as a wearing surface with sufficient roughness for skid resistance.

1.8.2.3 Drainage systems 1.8.2.3.1 General The spacing and capacity of bridge deck drains established by hydraulic design and testing shall be sufficient to ensure that for a ten-year design storm the runoff flowing in the swale or gutter will not encroach more than 1.50 m onto the traffic lane. Bridge deck drain inlets shall be provided only where this requirement would otherwise not be met. Where flat grades or sag curves are unavoidable, additional drainage shall be considered as a means of reducing local ponding.

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1.8.2.3.2 Deck drain inlets Drain inlets shall have grates with a clear spacing between bars of 40 to 75 mm. For highways from which cyclists are not excluded, grate bars shall be at an angle to the roadway centreline of between 45 and 90°. The top surface of a drain inlet grate shall be a minimum of 15 mm and a maximum of 25 mm below the plane of the wearing surface. The wearing surface around the drain inlet shall be sloped toward it from the general plane of the wearing surface at a slope of approximately 1 in 20.

1.8.2.3.3 Downspouts and downpipes The surface runoff collected at deck drain inlets shall be directed through the superstructure by individual vertical deck drain pipes with a minimum nominal inside diameter or width of 200 mm. Downpipes shall be rigid and made of corrosion-resistant material. Where it is necessary to direct water laterally, this shall be accomplished by running pipes as nearly vertical as possible. Changes in direction shall be not greater than 45°. Cleanouts shall be provided near bends or at intervals to permit access to all parts of a downpipe system. The location and length of downspouts shall be such that drainage will not be discharged or blown against any structural component. For design purposes, water shall be assumed to spread from the outlet at an angle of 45° from the vertical. Downspouts shall project a minimum of 150 mm below any adjacent component, except where prohibited by minimum vertical clearance requirements. Discharge from downpipes and downspouts shall be restricted to locations protected from erosion. Water shall not be discharged onto traffic or facilities such as roadways, pedestrian paths, and navigation channels. The probable performance of drainage systems at low temperatures shall be considered in the design, based on the behaviour of similar systems subject to local conditions, exposure, and maintenance standards, and shall take into account the consequences of freezing (including pipe bursting, deck flooding, and falling ice). The involvement of open deck joints in deck drainage shall be considered. Open troughs provided to collect runoff passing through the joint shall be large enough to contain the discharge, shall slope at an angle of not less than 30° to the horizontal, and shall in other respects meet the requirements for downspouts.

1.8.2.4 Subdrainage of wearing surface Provision shall be made for the drainage of water or for the release of pressure between waterproofing membranes and asphaltic concrete wearing surfaces. Drain holes with a minimum diameter of 15 mm shall be provided at this level in all deck drain inlets. At expansion joint dams or in other locations where a drainage pocket is formed, corrosion-resistant drainage tubes shall be installed to drain the trapped water and shall lead from the low point of the pocket to a location where the water can be discharged harmlessly.

1.8.2.5 Runoff and discharge from deck Runoff from the bridge deck at the abutments shall be intercepted immediately beyond the end of the bridge approach slab or before the end of the curb or barrier by catch basins or other suitable means. The intercepted water shall be directed away from the embankment slopes and abutments to prevent embankment erosion. Where approaches slope down toward a bridge, the runoff shall be intercepted by catch basins or other devices located on the approaches so as to minimize flow across the expansion joints and onto the bridge deck.

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1.8.3 Maintenance 1.8.3.1 Inspection and maintenance access 1.8.3.1.1 General The type of access needed for inspection and maintenance shall be considered in the design of all structures. Types of structures that have inaccessible areas where undetected dangerous deterioration can occur shall be avoided. Access to primary components requiring periodic inspection or maintenance shall be unhindered and not require equipment unlikely to be available.

1.8.3.1.2 Removal of formwork Unless otherwise Approved, all formwork shall be removed from the underside of concrete deck slabs and from the inside of steel and concrete box sections that have an inside vertical dimension of 1.20 m or more.

1.8.3.1.3 Superstructure accessibility The final structure site terrain and the need for access from below shall be reviewed during design to ensure ease of inspection of the primary components of superstructures. High bridges and bridges over deep water with individual spans longer than 30 m and not more than 75 m long shall be designed to permit inspection by mobile inspection equipment. For structures with spans longer than 75 m, consideration shall be given to providing catwalks or travelling-scaffold equipment.

1.8.3.1.4 Access to expansion joints A clear space of at least 200 mm shall be provided between the ballast walls and the superstructure end diaphragms and girders.

1.8.3.1.5 Access to primary component voids For box or cellular girders that have voids with an inside vertical dimension of 1.20 m or more, access hatches shall have a minimum clear opening size of 600 × 800 mm if rectangular or 800 mm in diameter if round. All voids or cells shall have an access hatch or an interior connection to a void that does. The interior connection openings shall not be smaller than the hatch openings. All hatches shall have close-fitting lockable covers. Where a void has access openings on the surface of structural components, the openings shall be fitted with cover plates of vandal-resistant design. All cover plates on manholes, hand holes, or other openings on the top surfaces of bridge components shall have weathertight seals. Drains shall be provided at all low points of voids and shall direct water to an area remote from structural components.

1.8.3.2 Maintainability Where it can reasonably be expected that components will have to be replaced or modified during the design life of the structure, methods of replacement shall be investigated to ensure the feasibility, acceptable cost, and duration of the work and, where appropriate, the availability of alternative routes or detours for traffic. This investigation shall ensure the availability of access and the integrity of the structure during the work.

1.8.3.3 Bearing maintenance and jacking Bridges with superstructures supported on bearings shall be designed to permit the jacking of the superstructure. Jack and shimming locations shall be shown on the drawings. The design shall allow for movement at the permanent bearing locations sufficient to permit bearing replacement.

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In the design of jack-bearing locations, the assumed factored jacking force shall not be less than twice the unfactored dead load. When closure of the structure to traffic is not practicable, a backup system of shim supports independent of the jacking equipment shall be provided and all loads shall be considered at the ultimate limit states for the jacking and shimming locations.

1.9 Hydraulic design 1.9.1 Design criteria 1.9.1.1 General The hydraulic design of bridges, culverts, and associated works shall comply with the requirements of the Regulatory Authority or, in their absence, with the Transportation Association of Canada’s Guide to Bridge Hydraulics. Acceptability criteria for the performance of structures in withstanding a design flood shall be in accordance with the intended level of service and normal economic constraints. Risks that are to be accepted shall be recorded as part of the design criteria.

1.9.1.2 Normal design flood The normal design flood shall have a return period of 50 years unless otherwise specified by the Regulatory Authority. Bridges and culverts shall be designed to accommodate the normal design flood without damage to the structure or the approaches. Relief flow over the roadway shall be allowed only with site-specific Approval and where geometric and level-of-service criteria permit. The site of the assumed relief flow shall be investigated to ensure that no significant damage or concealed hazards can arise.

1.9.1.3 Check flood The check flood shall have a return period of at least twice the normal design flood unless otherwise specified by the Regulatory Authority. Bridges and culverts shall be designed to withstand a check flood without endangering the integrity of the structure and without approach embankment failure.

1.9.1.4 Regulatory floods and relief flow When it is required that a structure be designed for the regulatory flood, relief flow shall be considered to the extent permitted by geometric, level-of-service, and other site criteria. The structure shall be designed for that part of the regulatory flood not accommodated by relief flow, without causing flooding of upstream property outside the established flood plain.

1.9.1.5 Design flood discharge The design flood discharge shall be estimated by Approved methods.

1.9.1.6 High-water levels Unless otherwise specified, the high-water levels used for design purposes shall be the water levels corresponding to the design flood discharge without ice jams. If the crossing is subject to abnormal flood conditions, the worst conditions for the particular design purpose likely to occur together with the design flood shall be assumed.

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1.9.2 Investigations For all water crossings, office studies and field surveys shall be carried out as part of the investigation of the proposed crossing site to determine (a) hydraulic characteristics; (b) geotechnical characteristics; (c) the location of all utilities in the area; (d) ownership of property that might be affected; (e) past and potential problems in the vicinity; (f) the hydraulic performance of existing structures near the site; (g) the flood history of the site; (h) the ice and debris history of the site; (i) other features pertinent to the hydraulic design; and (j) established and possible future land use trends and their effect on the waterway, flood plain, and watershed areas. When appropriate, other investigations, e.g., archaeological surveys or environmental studies, shall be conducted.

1.9.3 Location and alignment The selection of the location and alignment of a water crossing shall take into account the following factors: (a) the stability of the channel; (b) road geometrics and road user safety; (c) geotechnical conditions; (d) the effect of the crossing on adjacent structures and property; (e) the effects of adjacent dams, bridges, and other structures; (f) the interests of waterway users; and (g) any known future developments.

1.9.4 Estimation of scour 1.9.4.1 Scour calculations Depths of general scour, local scour, degradation, and artificial deepening of the channel shall be estimated at all structure sites. Scour calculations shall be prepared for all potentially critical conditions, including maximum depth of flow, maximum velocity, and extreme ice conditions. If abnormal flood conditions can occur at the site, a design flood discharge based on the lowest downstream water level likely to coincide with the design flood shall be considered.

1.9.4.2 Soils data The properties of the material below the estimated depth of maximum scour shall be examined to reduce the possibility of large errors in scour predictions.

1.9.4.3 General scour 1.9.4.3.1 Average depth The average depth of general scour shall be calculated using the competent velocity method or another Approved method and shall be referenced to the original stream bed.

1.9.4.3.2 Maximum depth The maximum depth of general scour at any point in a structure opening shall be determined by redistributing the average depth of general scour as described in the Transportation Association of Canada’s Guide to Bridge Hydraulics or using other Approved methods. The maximum depth of general

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scour shall be assumed to occur atany point across the structure opening except where protective features would prevent it.

1.9.4.4 Local scour The depth of local scour at a pier, abutment, or other obstruction shall be measured below the anticipated depth of general scour and shall be calculated using Approved methods. The possibility of local scour being caused or aggravated by ice jams or trapped debris shall be considered.

1.9.4.5 Total scour The total depth of scour at a point across a structure opening shall be taken as the sum of the maximum depth of general scour and the depth of local scour.

1.9.4.6 Degradation The probable depth of stream bed degradation during the design life of a structure shall be estimated by investigating the site and the characteristics and history of the channel.

1.9.4.7 Artificial deepening The amount of artificial deepening of a channel anticipated during the design life of a structure shall be obtained from drainage plans, if available. Otherwise, it shall be estimated from an investigation of existing structures on the same channel.

1.9.4.8 Allowance for degradation or artificial deepening The ultimate bed elevation at structures on channels subject to degradation or artificial deepening shall be taken as follows: (a) for degrading channels not having a concrete or steel invert that complies with Clause 1.9.5.7, the expected amount of degradation plus one-half the total scour; and (b) for channels likely to be artificially deepened, the expected amount of deepening plus the total scour.

1.9.5 Protection against scour 1.9.5.1 General Scour protection requirements for structure foundations shall be determined on the basis of the normal design flood and shall be modified if necessary to ensure that structural failure will not occur as a result of the check flood.

1.9.5.2 Spread footings 1.9.5.2.1 Depth of footings The following shall apply to depth of footings: (a) Minimum depth: except as specified in Items (b) to (e), the bottom surfaces of spread footings that could be exposed to stream flow shall be placed at the lowest of the following elevations: (i) a depth below the original bed not less than the following: (1) abutments other than arches: 1.50 m; and (2) piers and arch abutments: 2.00 m; (ii) a depth below the original bed not less than 1.7 times the estimated total depth of scour; and (iii) a depth not less than 0.50 m below the lowest level of existing or past scour. (b) Bedrock: spread footings may be founded on scour-resistant durable bedrock at a higher elevation than that specified by Item (a) if the depth is sufficient to ensure that they remain unaffected by scour, freezing, weathering, degradation, or artificial deepening during the design life of the structure.

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(c) Temporary structures: for temporary piers and abutments constructed of gabions or timber cribs, the depths specified in Items (a)(i) and (a)(iii) shall be reduced by half, and the factor specified in Item (a)(ii) shall be reduced from 1.7 to 1.3. (d) Degrading channels: on degrading channels that are not stabilized with a paved invert or revetment complying with Clause 1.9.5.7, the footing depth specified in Item (a)(ii) shall not be taken as less than the expected amount of degradation plus the estimated total depth of scour. (e) Artificial deepening: on channels likely to be artificially deepened, the footing depths specified in Items (a)(i) and (a)(ii) shall be measured below the expected stream bed elevation after deepening.

1.9.5.2.2 Protection of spread footings Spread footings shall not be founded at a depth less than that specified in Clause 1.9.5.2.1 unless (a) the structure opening has a concrete or steel invert complying with Clause 1.9.5.7; or (b) the footings are protected against undermining by sheet piling along the inside face and ends of the footings or by other Approved means. Spread footings adjacent to the stream channel shall not be founded at an elevation higher than the stream bed on material other than bedrock or rock fill unless protected by a concrete revetment complying with Clauses 1.9.5.7 and 1.9.9.3.

1.9.5.3 Piles 1.9.5.3.1 General In sands and other highly erodible soils, piles shall be used in preference to spread footings to provide better protection against the effects of scour.

1.9.5.3.2 Penetration and strength The penetration and structural strength of piles shall be sufficient to ensure their stability with the stream bed at its ultimate bed elevation.

1.9.5.3.3 Abutments supported on piles The bottom of footing elevation of abutments exposed to flowing water shall be set at least 1.0 m below the ultimate stream bed elevation. This requirement may be waived if footing protection meeting the requirements of Clause 1.9.5.2.2 is provided.

1.9.5.4 Sheet piling When required for scour protection, sheet piling shall comply with the following requirements: (a) the piling shall be securely attached to the footing or otherwise anchored to prevent movement; and (b) the penetration and structural strength of the piling shall be sufficient to ensure stability of the structure and piling with the stream bed at its ultimate bed elevation.

1.9.5.5 Protective aprons Flexible aprons used for protecting piers and abutments against local scour shall comply with the recommendations of the Transportation Association of Canada’s Guide to Bridge Hydraulics or those of the Regulatory Authority. Rip-rap stone sizes for aprons shall be determined by designing for a velocity 1.5 times the average velocity of the normal design flood discharge through the structure opening. The thickness of rip-rap aprons shall be not less than 1.5 times the median size of the stone.

1.9.5.6 Paved inverts and revetments Concrete and steel inverts and revetments that are needed to stabilize a channel at a structure shall have cut-off walls of sufficient depth and strength to prevent undermining. The cut-off walls shall be integral with or securely attached to the invert or revetment.

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1.9.5.7 Special protection against degradation Where a paved invert or revetment is required to stabilize a degrading stream bed, the following shall be provided: (a) Cut-off walls as specified in Clause 1.9.5.6. The downstream cut-off wall shall be designed to resist the maximum depth of degradation likely to occur during the design life of the structure or up to the time of scheduled stream bed maintenance. (b) An apron, energy dissipator, or other device to control erosion caused by the discharge from the structure. (c) If the invert is lower than the adjacent upstream bed, a sill, weir, or other effective control at the inlet.

1.9.6 Backwater 1.9.6.1 General Backwater shall be calculated using Approved methods. Backwater shall be limited so as to preclude damage to upstream property and buildings during the design flood. Unless otherwise Approved, the design flood shall be the normal design flood.

1.9.6.2 High-water level The high-water level used in the backwater calculations shall be as specified in Clause 1.9.1.6. If the crossing is subject to abnormal flood conditions, the highest downstream water level likely to occur together with the design flood shall be assumed.

1.9.6.3 Assumed depth of scour Unless otherwise Approved, the depth of scour assumed to have occurred in backwater calculations shall not be more than one-half the average depth of general scour calculated in accordance with Clause 1.9.4.3.

1.9.6.4 Waterway modification The enlargement of the natural channel cross-section at a bridge to reduce backwater shall be of such a nature as to provide a stable channel and preclude progressive sedimentation and growth of undesirable vegetation.

1.9.6.5 Reduction of backwater by relief flow Backwater calculations shall include relief flow over the roadway where allowed by Clause 1.9.1.2.

1.9.7 Soffit elevation 1.9.7.1 Clearance The clearance between the soffit of the structure and the high water level determined in accordance with Clause 1.9.7.2 shall be sufficient to prevent damage to the structure by the action of flowing water, ice floes, or debris, and unless otherwise Approved shall not be less than 1.0 m for freeways, arterial roads, and collector roads and not less than 300 mm for other roads. The clearance for a structure with an arched soffit shall be based on site-specific considerations. Vertical clearance for a structure on a navigable waterway shall be measured from the highest water level at which usual navigation is likely to occur. This level, together with the vertical and horizontal clearances, shall be determined in accordance with the Government of Canada’s Navigable Waters Protection Act. Unless otherwise Approved, the clearance between the lowest point of the soffit and normal water level shall be at least 1.0 m.

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1.9.7.2 High-water level for establishing soffit elevation 1.9.7.2.1 General Subject to Clause 1.9.7.2.2, and unless otherwise Approved for the site, the high-water level for establishing the minimum soffit elevation shall be the higher of (a) the high-water level determined in accordance with Clause 1.9.6.2; and (b) the high-water level caused by ice jams and having a return period comparable to that of the design flood.

1.9.7.2.2 Flooding and relief flow Use of the regulatory flood as the design flood to ensure that flooding of upstream property will not occur shall not require the soffit elevation to be higher than that required for the normal design flood, provided that adequate relief flow, as permitted by Clause 1.9.1.2, can occur.

1.9.8 Approach grade elevation 1.9.8.1 General Where geometric and other considerations permit, the approach grade shall be set so that the requirements of Clause 1.9.8.2 are met. If consideration of a regulatory flood is required and relief flow is permitted, the grade shall be set to optimize relief flow.

1.9.8.2 Freeboard Except when otherwise Approved, freeboard from the edge of through-traffic lanes to the high-water level determined in accordance with Clause 1.9.8.3 shall be 1.0 m for freeways, arterial roads, and collector roads and 300 mm for other roads.

1.9.8.3 High-water level for establishing approach grade The high-water level for establishing the approach grade elevation shall be as specified for establishing the minimum soffit elevation in Clause 1.9.7.2. Unless otherwise Approved, the high-water level upstream of the opening shall be increased by the estimated backwater.

1.9.8.4 Freeboard for routes under structures crossing water Freeboard for highways under bridges that cross water shall be in accordance with Clause 1.9.8.2. Freeboard for walkways, bicycle paths, and maintenance access roads under structures crossing water shall be at least 1.0 m above normal water level. This minimum value shall be increased when high maintenance costs are likely to result from its use.

1.9.9 Channel erosion control 1.9.9.1 Slope protection Where necessary, embankments shall be protected against erosion to prevent damage to the structure, roadway, or property affected by the crossing. The design of protection works shall be in accordance with the Transportation Association of Canada’s Guide to Bridge Hydraulics or as otherwise Approved.

1.9.9.2 Stream banks Stream banks shall be protected against erosion to the extent necessary to prevent damage to the highway or property affected by the crossing.

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1.9.9.3 Slope revetments Toe protection shall be provided to prevent undermining of slope revetments. Geotextile fabric, a graded granular filter blanket, or other Approved material shall be provided where necessary to prevent loss of underlying material. Unless otherwise Approved, a concrete revetment for protecting structure footings shall comprise concrete paving reinforced, tied, or interconnected in a way that ensures that the underlying material remains protected for the design life of the structure.

1.9.9.4 Storm sewer and channel outlets Outlets of storm sewers and channels discharging into or adjacent to a bridge or culvert opening shall have aprons, energy dissipators, drop structures, or other devices to prevent erosion that might endanger the bridge or culvert.

1.9.10 Stream stabilization works and realignment 1.9.10.1 Stream stabilization works Stabilization works shall be considered if one or more of the following is necessary: (a) stabilizing the channel location in the vicinity of the crossing; (b) reducing the cost of the crossing; (c) directing flow parallel to the piers and minimizing local scour; (d) improving the hydraulics of the waterway or reducing erosion; (e) protecting the roadway approaches from stream attack; (f) permitting the construction of a square crossing by diverting the channel from a skewed alignment; or (g) improving the location and geometry of the crossing. Stabilization works shall be designed to suit the requirements of the site and comply with the Transportation Association of Canada’s Guide to Bridge Hydraulics.

1.9.10.2 Stream realignment Stream realignment shall be considered only when no cost-effective alternative is possible. The design of stream realignments shall include an evaluation of environmental and hydraulic regime effects.

1.9.11 Culverts 1.9.11.1 General Closed-invert culverts shall be used in preference to open-footing culverts except where site conditions dictate the use of open-footing culverts.

1.9.11.2 Culvert end treatment End treatment shall be provided where there would otherwise be a possibility of uplift, piping, undermining, or damage due to ice or debris. End treatment in the form of an improved inlet shall be provided where there is a net benefit due to improved hydraulic efficiency. End treatments shall be of tested or established types.

1.9.11.3 Culvert extensions Extensions to existing culverts shall be designed to prevent internal blockages caused by changes of direction, changes in the shape of the cross-section, or changes in the number of openings or cells.

1.9.11.4 Alignment of non-linear culverts Unless otherwise Approved, changes of horizontal alignment shall be accomplished by gradual curves or by angular changes of direction not exceeding 15° at intervals of not less than 15 m.

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1.9.11.5 Open-footing culverts 1.9.11.5.1 Inerodible inverts An open-footing culvert with an inerodible invert shall be considered a closed-invert culvert.

1.9.11.5.2 Vertical clearance Soffit elevations for open-footing culverts shall comply with Clause 1.9.7, except that the minimum clearance shall be 300 mm.

1.9.11.6 Closed-invert culverts 1.9.11.6.1 Invert elevation The inverts of closed-invert culverts shall be located below the adjacent channel bed at an appropriate depth in order to (a) reduce the likelihood of hanging outlets and the undermining of culvert ends; (b) improve hydraulic efficiency; (c) enhance fish passage; (d) reduce the water velocity at the outlet; and (e) encourage natural sedimentation of the culvert floor and replication of natural habitat.

1.9.11.6.2 Artificial deepening If the channel is likely to be artificially deepened, the culvert invert elevation shall be based on the future channel elevation estimated in accordance with Clause 1.9.4.7.

1.9.11.6.3 Degrading channel In a degrading channel, a sill or weir shall be provided to maintain any difference in elevation between the culvert invert and the upstream bed.

1.9.11.6.4 Piping When soil properties and hydraulic conditions indicate that piping can occur along the barrel of a culvert, appropriate preventive measures, e.g., the use of clay seals, cut-off walls, or impermeable barriers, shall be taken.

1.9.11.6.5 Concrete box structures A cut-off wall shall be provided at each end of a concrete box culvert in accordance with Clause 1.9.5.6.

1.9.11.6.6 Soil-steel structures The following requirements shall apply to soil-steel structures: (a) End treatment: a cut-off wall, headwall, collar, or other Approved device shall be provided at the ends of soil-steel structures where it is necessary to protect the culvert against uplift, piping, or undermining. Connections to the culvert shall be designed to resist all possible uplift and earth pressure forces. Embankment slopes shall be modified where necessary to provide sufficient weight of fill to prevent hydraulic uplift of the inlet end. If a weir is provided at the inlet end, piping shall be prevented as required by Clause 1.9.11.6.4 and the possibility of uplift due to buoyancy shall be considered. (b) Camber: the camber requirements for all metal pipe culverts shall be calculated to accommodate longitudinal settlement and to prevent ponding within the culvert.

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Section 2 — Durability 2.1 2.2 2.3 2.3.1 2.3.2 2.3.3 2.4 2.4.1 2.4.2 2.5 2.6 2.7 2.8 2.9 2.10

Scope 34 Definitions 34 Design for durability 34 Design concept 34 Durability requirements 34 Structural materials 36 Aluminum 36 Deterioration mechanisms 36 Detailing for durability 36 Polychloroprene and polyisoprene 37 Polytetrafluoroethylene (PTFE) 37 Waterproofing membranes 37 Backfill material 37 Soil and rock anchors 37 Other materials 37

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Section 2 Durability 2.1 Scope This Section specifies requirements for durability that need to be considered during the design process in addition to this Code’s requirements for strength and serviceability. The requirements of this Section apply to the design of new bridges as well as to rehabilitation and replacement work.

2.2 Definitions The following definitions apply in this Section: Design life — a period of time specified by the Owner during which a structure is intended to remain in service. Durability — the capability of a component, product, or structure to maintain its function throughout a period of time with appropriate maintenance. Predicted service life — an estimated period of time for the service life based on actual construction data, condition surveys, environmental characterization, or experience. Service life — the actual period of time during which a structure performs its design function without unforeseen costs for maintenance and repair.

2.3 Design for durability 2.3.1 Design concept The design shall ensure that the structure will be able to maintain its level of serviceability during its design life. The designer shall consider the environmental conditions that exist at the site or are likely to exist during the design life of the structure and shall assess their significance in relation to the possible mechanisms of deterioration in the structure. Structural site investigation shall include testing of soils, groundwater, local runoff water, atmospheric pollution levels, and, when applicable, drainage system discharge (to detect corrosive substances). When a structure is being designed for a new facility, environmental conditions shall be predicted from comparable existing facilities. The requirements for durability protection and the planned replacement of components shall be identified and shown on the Plans.

2.3.2 Durability requirements 2.3.2.1 General The structural form, materials, and details shall be suitable for the design loads and environmental conditions that will be experienced during the design life of the structure.

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2.3.2.2 Materials The composition, properties, and performance of the materials selected for the structure shall be specified by taking into account the design loads and the expected environmental degradation during the design life of the structure. Note: See also Clause 2.3.3.

2.3.2.3 Structural details Members shall be designed to reduce the impact of environmental factors. Preference shall be given to structural details that provide free air circulation for all above-ground components. Members shall be detailed to minimize exposed surface area and avoid pockets, crevices, recesses, re-entrant corners, and locations that collect and retain water, debris, and moisture.

2.3.2.4 Bearing seats Bearing seats shall be designed so that contact with de-icing salts, salt-laden water runoff, leakage, and debris is prevented. The surfaces around and between bearing seats shall be sloped so that they are self-draining away from the bearings. Level areas for jacking of the superstructure for bearing replacement shall be provided.

2.3.2.5 Bridge joints 2.3.2.5.1 Expansion and/or fixed joints in decks Wherever practical, expansion and/or fixed joints in decks shall be avoided or placed in the approach pavements. Where expansion joints cannot be avoided, they shall be detailed to prevent damage to components of the structure from water, de-icing salts, chemicals, and roadway debris. End floor beams and end diaphragms under expansion joints shall be arranged to permit coating and future maintenance of surfaces that are exposed to surface runoff. The end diaphragms of box girders shall be detailed to prevent ingress of water into the boxes. The end diaphragms of slab-on-girder bridges shall be detailed to prevent water from expansion joints travelling along girders.

2.3.2.5.2 Joints in abutments, retaining walls, and buried structures Expansion and construction joints in abutments, retaining walls, and buried structures shall be sealed at the surface that is in contact with the backfill to prevent damage to components of the structure from water, de-icing salts, and chemicals.

2.3.2.6 Drainage The longitudinal and transverse slopes on bridge decks and the number and location of deck drains shall be in accordance with Section 1. Downspouts for deck drains shall be located in such a way that runoff water is discharged away from any part of the bridge. Downspouts shall extend at least 150 mm below adjacent members. Wherever practical, deck drains shall not pass through the box girders. Box girders shall be made watertight at their ends and adequately drained so as to reduce the potential for moisture entrapment and accelerated corrosion. Pockets and depressions that could retain water shall have effective drain holes or an alternative means of drainage. Measures shall be taken to prevent erosion from the discharge of drainage water.

2.3.2.7 Utilities All permanent iron and steel utility supports, fittings, and accessories shall be coated or galvanized. Utility supports shall be designed to prevent stray electrical currents between the structure and the utility supports.

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2.3.2.8 Birds and other animals In areas with large roosting bird populations, components shall be located and proportioned in a way that prevents the entry or roosting of birds in drain holes, expansion joints, and bearing cavities. In the absence of such measures, screening or other Approved methods shall be used to inhibit bird roosting. Voids shall be designed to prevent the entry of birds and other animals.

2.3.2.9 Access Access for maintenance and inspection shall be provided for all components of the structure.

2.3.2.10 Construction The quality of the materials, placement procedures, and construction details shall be specified on the Plans. The testing and acceptance methods required at the site for quality assurance of materials and construction shall be specified on the Plans.

2.3.2.11 Inspection and maintenance The design of bridges and other structural components shall be predicated on routine inspection and maintenance procedures being instituted.

2.3.3 Structural materials The designer shall review the environmental conditions and deterioration mechanisms for the material used and shall apply the following durability requirements to achieve the design life of the structure: (a) for concrete: Clause 8.11; (b) for wood: Clause 9.17; (c) for steel, including steel components of bearings, expansion joints, light poles, overhead sign supports, soil-steel structures, deck drains, and railings: Clause 10.6; (d) for fibre-reinforced structures: Clause 16.4 and Annexes A16.1 and A16.2; (e) for aluminum: Clause 2.1; and (f) for other materials: Clauses 2.5 to 2.10.

2.4 Aluminum 

2.4.1 Deterioration mechanisms The deterioration mechanisms to be considered for aluminum components shall include, but not be limited to, corrosion. More information can be found in Clause 17.6.

2.4.2 Detailing for durability 2.4.2.1 Connections Aluminum components shall be connected by welding, by stainless steel bolts, or by high-strength steel bolts galvanized in accordance with CAN/CSA-G164. In hot and very humid conditions, the surface between the galvanized bolt and the aluminum shall be coated with paint or bitumastic materials.

2.4.2.2 Inert separators Inert separators shall be provided where aluminum components are in contact with other metals (except stainless steel) or concrete.

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2.5 Polychloroprene and polyisoprene The properties specified for polychloroprene and polyisoprene shall ensure that the materials will not harden or crack in the environment in which they are used.

2.6 Polytetrafluoroethylene (PTFE) PTFE surfaces in contact with stainless steel shall be free of dirt to prevent excessive friction.

2.7 Waterproofing membranes Waterproofing membranes shall prevent the ingress of water and shall not crack during their service life. Only Approved waterproofing membranes shall be specified. Where a hot applied rubberized asphalt waterproofing membrane is used, it shall be protected with an asphalt-impregnated protection board to prevent it from being punctured. The membrane shall terminate in a chase in the curb or barrier wall. The top surfaces of a waterproofing membrane shall be drained to prevent ponding of water on the membrane.

2.8 Backfill material Backfill material shall be free draining and shall not contain corrosive chemicals that could have a detrimental effect on structural components in contact with the backfill material.

2.9 Soil and rock anchors Soil and rock anchors shall be protected from the detrimental effects of chemicals in the soil and rock or shall be made from inert materials.

2.10 Other materials The composition, properties, and performance of materials not covered in this Section shall be specified by taking into account the design loads and expected environmental degradation during the design life of the structure.

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Section 3 — Loads 3.1 3.2 3.3 3.3.1 3.3.2 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.5 3.5.1 3.5.2 3.5.3 3.5.4 3.6 3.7 3.7.1 3.7.2 3.8 3.8.1 3.8.2 3.8.3 3.8.4 3.8.5 3.8.6 3.8.7 3.8.8 3.8.9 3.8.10 3.8.11 3.8.12 3.9 3.9.1 3.9.2 3.9.3 3.9.4 3.10 3.10.1 3.10.2 3.10.3 3.10.4 3.10.5 3.11 3.11.1 3.11.2 3.11.3 3.11.4 3.11.5 3.11.6 3.11.7

Scope 41 Definitions 41 Abbreviations and symbols 43 Abbreviations 43 Symbols 43 Limit states criteria 47 General 47 Ultimate limit states 47 Fatigue limit state 47 Serviceability limit states 47 Load factors and load combinations 48 General 48 Permanent loads 50 Transitory loads 51 Exceptional loads 51 Dead loads 51 Earth loads and secondary prestress loads 52 Earth loads 52 Secondary prestress effects 52 Live loads 52 General 52 Design lanes 52 CL-W loading 52 Application 54 Centrifugal force 56 Braking force 56 Curb load 56 Barrier loads 56 Pedestrian load 57 Maintenance access loads 57 Maintenance vehicle load 57 Multiple-use structures 57 Superimposed deformations 58 General 58 Movements and load effects 58 Superstructure types 58 Temperature effects 59 Wind loads 61 General 61 Design of the superstructure 62 Design of the substructure 63 Aeroelastic instability 64 Wind tunnel tests 65 Water loads 65 General 65 Static pressure 65 Buoyancy 65 Stream pressure 65 Wave action 66 Scour action 66 Debris torrents 66

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3.12 3.12.1 3.12.2 3.12.3 3.12.4 3.12.5 3.12.6 3.13 3.14 3.14.1 3.14.2 3.14.3 3.14.4 3.14.5 3.14.6 3.14.7 3.15 3.16 3.16.1 3.16.2 3.16.3 3.16.4 3.16.5

© Canadian Standards Association

Ice loads 67 General 67 Dynamic ice forces 67 Static ice forces 69 Ice jams 69 Ice adhesion forces 69 Ice accretion 69 Earthquake effects 69 Vessel collisions 70 General 70 Bridge classification 70 Assessment 70 Annual frequency of collapse 70 Design vessel 70 Application of collision forces 70 Protection of piers 71 Vehicle collision load 71 Construction loads and loads on temporary structures 71 General 71 Dead loads 71 Live loads 71 Segmental construction 71 Falsework 72

Annexes A3.1 (normative) — Climatic and environmental data 73 A3.2 (normative) — Wind loads on highway accessory supports and slender structural elements 94 A3.3 (normative) — Vessel collision 104 A3.4 (normative) — CL-625-ONT live loading 113

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Section 3 Loads 3.1 Scope This Section specifies loads, load factors, and load combinations to be used in calculating load effects for design. Resistance factors required to check ultimate limit states criteria in accordance with Clause 3.4.2 are specified elsewhere in this Code. Loadings provisions for evaluation of existing structures are covered in Section 14 and for rehabilitation in Section 15. This Section includes requirements related to the vibration of highway and pedestrian bridges. It also includes requirements related to construction loads and temporary structures; these apply to partially completed structures and structures necessary for construction purposes. Snow loads are not specified because in normal circumstances the occurrence of a considerable snow load will cause a compensating reduction in traffic load.

3.2 Definitions The following definitions apply in this Section: Acceptance criterion — the acceptable frequency of collapse due to the design vessel collision. Buffeting — the loads induced in a structure by the turbulence in the natural wind. Damping — the dissipation of energy in a structure oscillating in one of its natural modes of vibration. It is normally expressed as a ratio of the actual value of damping to the critical value of damping. The critical value of damping is the lowest value at which an initial motion decays without oscillation. Dead load — the load from material that is supported by the structure and is not subject to movement. Debris torrent — a mass movement that involves water-charged inorganic and organic material flowing rapidly down a steep confined channel. Design lane — a longitudinal strip that is a fraction of the deck width and within which a Truck or Lane Load is placed for the purpose of design or evaluation. Divergence — an aerodynamic instability in torsion that usually occurs at wind speeds higher than those normally considered in design. Drag — the load in the direction of the wind, induced by an airstream acting on a body. Dynamic load allowance — an equivalent static load that is expressed as a fraction of the traffic load and is considered to be equivalent to the dynamic and vibratory effects of the interaction of the moving vehicle and the bridge, including the vehicle response to irregularity in the riding surface. Effective temperature — the temperature that governs the thermally induced expansion and contraction of a superstructure. Exceptional loads — the loads due to forces of nature or accident that would not be expected to occur more than once in the life of a bridge.

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Exposed frontal area — the net area of a body, member, or combination of members as seen in elevation. For a superstructure, the sum of the areas of all members, including railings and the deck system, as seen in elevation at 90° to the longitudinal axis in the case of a straight structure or to an axis chosen to maximize wind effects in the case of a structure that is curved in plan. Exposed plan area — the net area of an object as seen in plan from above. For a superstructure, the plan area of the deck and of any laterally protruding railings, members, or attachments. Factored load — the product of a load specified in this Code and the corresponding load factor. Factored load effect — the load effect caused by a factored load. Falsework — a temporary structure used to support another structure or a part of the other structure. Flexural frequency — a natural frequency of vibration of an unloaded bridge based on the longitudinal flexural stiffness and mass distribution of the superstructure. Flutter — an instability caused by the interaction of the wind and the bridge structure involving either pure torsional motion or coupled vertical and torsional motion of a bridge deck. Galloping — the cross-wind vibrations that arise from the aerodynamic instability of many slender structures. Gust effect coefficient — the ratio of the peak wind-induced load on a structure or response of a structure, including both static and dynamic action, to the static wind-induced load or response. It is also referred to as the gust coefficient. Ice accretion — the buildup of an ice layer on the exposed surfaces of a body due to freezing rain or in-cloud icing. Live load — a load imposed by vehicles, pedestrians, equipment, or components that are subject to movement. Load — a load, force, deformation, or volumetric change that is imposed externally on or internally within a structure. Natural frequency — the frequency of vibration of one of the natural modes of a bridge, expressed in cycles per second, and being the inverse of the natural period. Natural period — the duration of one complete cycle of free vibration of a normal mode of vibration of a structure. Normal mode shape — the geometric configuration of a structure associated with vibration at one of its natural frequencies. Pedestrian load — the load due to pedestrians on a bridge. Permanent loads — the loads that do not vary unless physical changes are made to the bridge. Reynolds number — the ratio of inertial forces to viscous forces of a fluid. Service life — the number of years a structure is intended to be in use. Slender structural element — a structural member with an aspect ratio of 20 or more. Strouhal number — a non-dimensional parameter that characterizes the frequency of vortex shedding and represents the ratio of the width of a body placed in an airstream to the wavelength of vortices shed from the body. Structural component — a component that influences the strength or stiffness of a structure.

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Traffic barrier — a barrier that is intended to provide protection to vehicular traffic. Traffic load — the load due to vehicles on a bridge. Transitory loads — the loads due to traffic or equipment on a structure, or the seasonal effects of nature. Travelled lane — a strip of roadway marked for use by a single line of vehicles. Vessel collision — the impact of a ship with the substructure or superstructure of a bridge over a navigable waterway. Vortex shedding — an instability of the wake behind a bluff (i.e., not streamlined) body in an airstream, comprising a more or less periodic shedding of vortices. The vortices are shed alternately from opposite sides of the body, producing an alternating lateral load normal to the wind direction. Wake buffeting — the loads induced in a structure by the turbulence caused by the wake of an upwind structure. Water loads — the loads from static or moving water, including pressure, buoyancy, waves, and debris torrents.

3.3 Abbreviations and symbols 3.3.1 Abbreviations The following abbreviations apply in this Section: CL FLS PL-1 PL-2 PL-3 SLS ULS

— Canadian loading (see Clause 3.8.3) — fatigue limit state — performance level 1 for traffic barriers — performance level 2 for traffic barriers — performance level 3 for traffic barriers — serviceability limit state — ultimate limit state

3.3.2 Symbols The following symbols apply in this Section: A

= area of a pier or drift exposed to flowing water, projected parallel to the longitudinal axis of the pier onto a plane perpendicular to that axis, m2 (see Clause 3.11.4.1); zonal acceleration ratio (dimensionless) (see Table A3.1.1); ice accretion load (see Tables 3.1 and A3.2.1)

AF

= annual frequency of collapse for a pier or span component susceptible to ship collision

AFmax = maximum annual frequency of collapse for a whole bridge due to vessel collision ai

= modal coefficient of magnitude of the oscillatory displacement for the member mode of vibration, i, for a member with a constant diameter or frontal width, m

ai (x1) = modal coefficient of magnitude of the oscillatory displacement due to vortex shedding excitation at location x1 for the member mode of vibration, i, for a member with a tapered diameter or frontal width, m B

= band width (a measure of the variability of the vortex shedding frequency) (see Table A3.2.4); width of ship, m (see Clause A3.3.3.3.5)

BL

= basic load (see Clause A3.2.3)

BR

= aberrancy base rate for vessels

b

= width of the traffic signal (see Figure A3.2.1); length of the member above or below location x1 for which D(x) is within a certain percentage of D(x1), m (see Clause A3.2.4.3.1(b))

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C

= a onstant c see ( Clause A3.2.4.3.1)

CD

= horizontal wind drag coefficient of a cylindrical shape with a diameter of D (see Table A3.2.2); longitudinal drag coefficient for stream pressure (see Table 3.10)

CH

= hydrodynamic mass coefficient

CL

= lateral load coefficient for stream pressure (see Table 3.11)

CL

= root-mean-square (RMS) lift coefficient for the cross-sectional geometry (see Table A3.2.4)

˜

Ca

= coefficient allowing for the ratio of pier width to ice thickness when the ice fails by crushing

Ce

= wind exposure coefficient

Cg

= wind gust effect coefficient

Ch

= horizontal wind drag coefficient

Cn

= coefficient of pier nose inclination

Cv

= vertical wind load coefficient

D

= dead load (see Tables 3.1 and A3.2.1); width or diameter of member (see Table A3.2.2); constant diameter or frontal width of member (see Clauses A3.2.4.2 and A3.2.4.3.1(a))

DB

= total height of vessel, m

DE

= depth of earth cover between the riding surface and the highest point of a structure, m

DWT

= dead weight tonnage of vessel, t

D(x)

= diameter or frontal width of a tapered member at location x, m (see Clauses A3.2.4.2 and A3.2.4.3.1(b))

d

= depth of superstructure, m

E

= loads due to earth pressure and hydrostatic pressure, including surcharges but excluding dead load (see Tables 3.1 and A3.2.1)

EQ

= earthquake load (see Tables 3.1 and A3.2.1)

e

= eccentricity of wind load on a sign, luminaire, traffic signal support, m

F

= loads due to stream pressure and ice forces or to debris torrents (see Table 3.1)

Fb

= horizontal ice load caused when ice floes fail by flexure, kN; horizontal ice force caused by floes that fail to flex on impact and ride on the inclined pier nose, kN

Fc

= horizontal ice load caused when ice floes fail by crushing, kN

Fh

= horizontal wind load per unit exposed frontal area, Pa

Fi (x)

= peak inertia load at location x for member mode of vibration, i, N/m

Ft

= transverse ice force, kN

Fv

= vertical wind load per unit exposed plan area, Pa (see Clause 3.10.2.3); vertical force on a bridge pier due to ice adhesion, kN (see Clause 3.12.5)

Fw

= force against a flat surface due to wave action, kN

GMi

= generalized mass for mode of vibration, i, kg

H

= depth of flowing water at a pier, m (see Clause 3.11.4.2); collision load arising from highway vehicles or vessels (see Table 3.1); height above ground of the top of a superstructure, m (see Clause 3.10.1.4); length of member, m (see Clause A3.2.4.3.1); ultimate bridge element strength, MN (see Clause A3.3.3.3.6)

Hw

= wave height, m

K

= all strains, deformations, and displacements and their effects, including the effects of their restraint and the effects of friction or stiffness in bearings. Strains and deformations include strains and deformations due to temperature change and temperature differential, concrete shrinkage, differential shrinkage, and creep, but not elastic strains (see Tables 3.1 and A3.2.1)

KE

= kinetic energy of a moving vessel, MN•m

k

= factor for calculation of load factor for wind effects, as determined by wind tunnel tests

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L

= length of a pier along the longitudinal axis, m (see Clause 3.11.4.2); live load (i.e., all applicable loads specified in Clause 3.8, including the dynamic load allowance, when applicable) (see Table 3.1); correlation length over which the vortices act in phase, m (see Table A3.2.4)

Lc

= width of horizontal clearance from pier(s), m

Lp

= perimeter of an oblong pier (excluding half-circles at the ends), m

m(x)

= mass per unit length of member at location x, kg/m

N

= number of vessels passing under a bridge

n

= number of design lanes on a bridge

ne

= frequency at which vortex shedding occurs for a member with constant diameter or frontal width, Hz

ne(x)

= frequency at which vortex shedding excitation occurs at location x for a member with a tapered diameter or frontal width, Hz (see Clause A3.2.4.2)

ni

= natural frequency of a member for mode of vibration, i, Hz

P

= total load due to flowing water acting on a pier in the direction of its longitudinal axis, N (see Clause 3.11.4); secondary prestress effects (see Tables 3.1 and A3.2.1); vessel impact force, MN (see Clause A3.3.3.3.6)

PBH

= ship bow collision force on an exposed superstructure, MN

PDH

= ship deck house collision force on a superstructure, MN

PMT

= ship mast collision force on a superstructure, MN

PS

= ship collision force, MN

Pp

= total load due to flowing water acting on a pier in the horizontal direction perpendicular to its longitudinal axis, N

PA

= probability of vessel aberrancy

PC

= probability of bridge collapse due to a collision with an aberrant vessel

PG

= geometric probability of a collision between an aberrant vessel and a bridge pier or span

p

= effective crushing strength of ice, kPa (see Clause 3.12.2); pedestrian load, kPa (see Clause 3.8.9)

q

= hourly mean reference wind pressure for the design return period, Pa

R

= radius of a circular pier, m; radius of half-circles at the ends of an oblong pier, m; radius of a circle that circumscribes each end of an oblong pier whose ends are not circular in plan at water level, m (see Clause 3.12.5)

RB

= correction factor for bridge location to determine probability of vessel aberrancy

RBH

= ratio of exposed superstructure depth to total bow depth

RC

= correction factor for current acting parallel to vessel transit path to determine probability of vessel aberrancy

RD

= correction factor for vessel traffic density to determine probability of vessel aberrancy

RDH

= reduction factor for deck house collision force (see Clause A3.3.7.2)

RXC

= correction factor for cross-currents acting perpendicular to vessel transit path to determine probability of vessel aberrancy

Re r

= Reynolds number (dimensionless) (see Table A3.2.4) = radius of curve, m (see Clause 3.8.5); ratio of corner radius to radius of inscribed circle (see Table A3.2.2) = Strouhal number (dimensionless) (see Clause A3.2.4.2); load due to differential settlement and/or movement of the foundation (see Tables 3.1 and A3.2.1) = total loaded length of walkway, m = torque on a support, N•mm = thickness of ice expected to make contact with a pier, m (see Clause 3.12)

S s T t

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tc

= transverse component of wind load, N

V

= hourly mean wind speed, m/s (see Clause A3.2.4.2); wind load on traffic (see Table 3.1); seismic zonal velocity ratio (dimensionless) (see Table A3.1.1); design collision velocity, m/s (see Clause A3.3.5)

VC

= current velocity component parallel to vessel transit path, m/s

VT

= typical vessel transit velocity, m/s

VXC

= current velocity component perpendicular to vessel transit path, m/s

Vmin

= minimum collision velocity, m/sec

Vref

= reference wind speed at deck height, m/s

Vw

= coefficient of variation of wind effects, as determined by wind tunnel tests

v

= design speed of a highway, km/h (see Clause 3.8.5); water velocity at the design flood, at SLS and ULS, m/s (see Clause 3.11.4)

W

= gross load of the idealized Truck, kN (see Clause 3.8.3.2); vessel displacement tonnage, t (see Clause A3.3.6); wind load on structure (see Tables 3.1 and A3.2.1)

Wa

= total normal wind load on a luminaire, sign panel, or traffic signal, N

Wc

= deck width, m

We

= width of design lane, m

Wh

= total normal wind load on exposed horizontal supports, N

Wv

= total normal wind load on exposed vertical supports, N

w

= frontal pier width at the level of ice action where the ice is to be split or crushed, measured perpendicular to the direction of ice motion, m

X

= distance to bridge element from centreline of vessel transit path, m

XC

= distance to edge of channel from centreline of vessel transit path, m

XL

= distance equal to three times the overall length of the design vessel from centreline of vessel transit path, m

x

= coordinate describing length along the member, m

yi (x)

= peak member displacement due to vortex shedding excitation at location x for member mode of vibration, i, m

Za

= acceleration-related seismic zone (see Table A3.1.1)

Zv

= velocity-related seismic zone (see Table A3.1.1)

ZW

= width of zone of vessel collision, m

α

= pier nose angle to the horizontal plane, degrees, as shown in Figure 3.7; wind velocity profile exponent (see Clause A3.2.4.3.1)

αD αE αP αw β ΔT δw ζi θ θf μi(x)

46

=

load factor for dead load

= load factor for earth pressure and hydrostatic pressure = load factor for secondary prestress effects = load factor for wind effects = subtended nose angle of an angular pier edge, degrees, as shown in Figure 3.7 = temperature differential, °C = bias coefficient of wind effect, as determined by wind tunnel tests = structural damping for the i th mode, expressed as a ratio of critical damping = angle between the direction of flow and the longitudinal pier axis, degrees (see Clause 3.11.4.2); angle of the turn of bend in channel, degrees (see Clause A3.3.3.3.1) = friction angle between ice and pier nose, degrees = amplitude of the member mode shape at location x for mode of vibration, i

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ρ = density of water, kg/m3 (see Clause 3.11.4); air mass density, kg/m3 (see Clause A3.2.4.3.1) ψ ( x 1) = shape factor for member taper

3.4 Limit states criteria 3.4.1 General Bridge design shall be based on the limit states philosophy specified in Clause 1.4.2.1.

3.4.2 Ultimate limit states Design shall provide a factored resistance that always exceeds the total factored load effect. Any structure where the total factored load effect could result in overturning, uplift, or sliding for any load combination shall be provided with anchorages.

3.4.3 Fatigue limit state Structural components shall satisfy the requirements for the fatigue limit state specified in the applicable Sections of this Code for the appropriate loading combinations.

3.4.4 Serviceability limit states Structural components shall satisfy the requirements for the serviceability limit states specified in the applicable Sections of this Code for the appropriate loading combinations. Superstructure vibration limitations shall be considered a serviceability limit state. Superstructures other than long-span bridges shall be proportioned so that the maximum deflection due to the factored traffic load, including the dynamic load allowance, does not exceed the limit shown in Figure 3.1 for the anticipated degree of pedestrian use. The deflection limit shall apply at the centre of the sidewalk or, if there is no sidewalk, at the inside face of the barrier. The traffic load shall be as specified in Clause 3.8.4.1(c). An Approved method shall be used to ensure that vibration likely to occur in normal use will not cause discomfort or concern to users of a pedestrian bridge.

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1000 500 UNACCEPTABLE

200

Static deflection, mm

Without sidewalks 100

With sidewalks — occasional pedestrian use

50

With sidewalks — frequent pedestrian use

20 10 5 ACCEPTABLE

2 1

0

1

2

3

4

5

6

7

8

9

10

First flexural frequency, Hz

Figure 3.1 Deflection limits for highway bridge superstructure vibration (See Clause 3.4.4.)

3.5 Load factors and load combinations 3.5.1 General The loading combinations to be considered and the load factors to be used shall be as specified in Tables 3.1 and 3.2 unless otherwise specified in Clause 3.5. Calibration of load factors and resistance factors shall be based on a minimum annual reliability index of 3.75 for CL-625 loading in accordance with Clause 3.8.3. Every load that is to be included in a load combination shall be multiplied by the specified load factor and the resulting load effects shall be calculated. The factored load effects shall then be added together to obtain the total factored load effect. If wind tunnel tests are used to derive wind loads, the wind load factors shall be as specified in Clause 3.10.5.2. The load factors for the effects of elastic distortions shall be those of the loads causing the distortion. The load combinations for highway accessory supports and slender structural elements shall be as specified in Annex A3.2. The total factored load effect used for each applicable load combination for construction loads shall not be less than 1.25 times the sum of the unfactored load effects included in the combination, unless otherwise Approved.

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Table 3.1 Load factors and load combinations



(See Clauses 3.5.1, 3.10.1.1, 3.10.5.2, 3.13, 3.16.3, 4.10.7, 4.10.10.1, 7.6.3.1.1, 7.7.3.1.1, 9.4.2, and 15.6.2.4.)

Loads

Permanent loads

Transitory loads

D

Exceptional loads

E

P

L*

K

W

V

S

EQ

F

A

H

11.00

1.00

1.00

1.00

0

0

0

0

0

0

0

0

1.00 0

1.00 0

1.00 0

0.90 0.90

0.80 0

0 0

0 0

1.00 0

0 0

0 0

0 0

0 0

D D D D D D D D

E E E E E E E E E

P P P P P P P P P

1.70†† 1.60 1.40 0 0 0 0 0 0

0 1.15 1.00 1.25 0 0 0 0 0

0 0 0.45§ 1.50§ 0 0 0.80§ 0 0

0 0 0.45 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 1.00 0 0 0 0

0 0 0 0 0 1.30 0 0 0

0 0 0 0 0 0 1.30 0 0

0 0 0 0 0 0 0 1.00 0

Fatigue limit state FLS ombination C Serviceability limit states SLS Combination 1 SLS Combination 2† Ultimate limit states‡ ULS Combination 1 ULS Combination 2 ULS Combination 3 ULS Combination 4 ULS Combination 5 ULS Combination 6** ULS Combination 7 ULS Combination 8 ULS Combination 9

1.35

*For the construction live load factor, see Clause 3.16.3. †For superstructure vibration only. ‡For ultimate limit states, the maximum or minimum values of  D ,  E , and P specified in Table 3.2 shall be used. §For wind loads determined from wind tunnel tests, the load factors shall be as specified in Clause 3.10.5.2. **For long spans, it is possible that a combination of ice load F and wind load W will require investigation. ††Also to be applied to the barrier loads. Legend: A= ice accretion load D= dead load E= loads due to earth pressure and hydrostatic pressure, including surcharges but excluding dead load EQ = earthquake load F= loads due to stream pressure and ice forces or to debris torrents H= collision load arising from highway vehicles or vessels, excluding barrier loads K= all strains, deformations, and displacements and their effects, including the effects of their restraint and the effects of friction or stiffness in bearings. Strains and deformations include strains and deformations due to temperature change and temperature differential, concrete shrinkage, differential shrinkage, and creep, but not elastic strains L= live load (including the dynamic load allowance, when applicable), including barrier loads P = secondary prestress effects S = load due to differential settlement and/or movement of the foundation V = wind load on traffic W = wind load on structure

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Table 3.2 Permanent loads — Maximum and minimum values of load factors for ULS (See Clauses 3.5.1, 3.5.2.1, 4.4.1, 4.4.9.3, and 7.8.7.1 and Table 3.1.) Dead load

Maximum  D

Minimum  D

Factory-produced components, excluding wood Cast-in-place concrete, wood, and all non-structural components Wearing surfaces, based on nominal or specified thickness Earth fill, negative skin friction on piles Water

1.10 1.20

0.95 0.90

1.50 1.25 1.10

0.65 0.80 0.90

Dead load in combination with earthquakes

Maximum  D

Minimum  D

All dead loads for ULS Combination 5 (see Table 3.1)

1.25

0.80

Earth pressure and hydrostatic pressure

Maximum  E

Minimum  E

Passive earth pressure, considered as a load* At-rest earth pressure Active earth pressure Backfill pressure Hydrostatic pressure

1.25 1.25 1.25 1.25 1.10

0.50 0.80 0.80 0.80 0.90

Prestress

Maximum  P

Minimum  P

Secondary prestress effects

1.05

0.95

*When passive earth pressure is considered as a resistance, it is factored in accordance with Section 6.

3.5.2 Permanent loads 3.5.2.1 General Total factored load effects shall include those effects due to all permanent loads acting on the structure. For ULS loading combinations, the maximum or minimum value specified in Table 3.2 for each load factor shall be used to maximize each total factored load effect. However, it is not normally necessary to consider load factors having different values in different spans. Except as required by Clause 3.5.2.2, the minimum values for load factors specified in Table 3.2 shall not be used for some loads together with maximum values for other loads when the possibility of these loads having minimum and maximum values simultaneously can safely be excluded.

3.5.2.2 Overturning and sliding effects

When the maximum value of  E for active pressure is used in calculating overturning for cantilever earth-retaining structures and for horizontal sliding, a value of 1.00 shall be used for  D. In calculating backfill pressures that oppose one another or reduce load effects within a structure, all combinations of maximum and minimum earth pressure load factors shall be considered. In calculating overturning moments occurring during balanced cantilever construction of segmental concrete bridges, maximum and minimum values of  D equal to 1.05 and 1.0, respectively, may be used for the erected segments provided that construction controls are specified to ensure that the difference in weight between any two segments forming a balancing pair does not exceed 5%, and that all differences in weight are corrected before the addition of further segments.

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3.5.3 Transitory loads Transitory loads shall be included in the loading combinations only if there is a possibility of the loads being applied to the structure at the stage considered and their inclusion increases the total factored load effect.

3.5.4 Exceptional loads Exceptional loads shall be included in the loading combinations only if there is a possibility of the loads being applied to the structure at the stage considered and their inclusion increases the total factored load effect.

3.6 Dead loads Dead loads shall include the weight of all components of the structure and appendages fixed to the structure, including wearing surface, earth cover, and utilities. In the absence of more precise information, the unit material weights specified in Table 3.3 shall be used in calculating dead loads. The weight of water shall be considered dead load. Other static effects, including lateral or upward water pressure and buoyancy, shall be considered hydrostatic pressures. The assumed water level shall be the maximum or minimum probable level, whichever produces the worst effect.

Table 3.3 Unit material weights (See Clause 3.6.)

November 2006

Material

Unit weight, kN/m3

Aluminum alloy Bituminous wearing surface Concrete Low-density concrete Semi-low-density concrete Plain concrete Prestressed concrete Reinforced concrete Coarse-grained (granular) soil Crushed rock Fine-grained sandy soil Glacial till Rockfill Slag Air-cooled slag Water-cooled slag Steel Water Fresh water Salt or polluted water Wood Hardwood Softwood

27.0 23.5 18.1 21.0 23.5 24.5 24.0 22.0 22.0 20.0 22.0 21.0 11.0 15.0 77.0 9.8 10.5 9.5 6.0

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3.7 Earth loads and secondary prestress loads 3.7.1 Earth loads Earth loads, other than those applied as dead loads, shall be as specified in Section 6. The requirements of Section 7 shall apply to buried structures.

3.7.2 Secondary prestress effects Secondary prestress effects shall be as specified in Section 8.

3.8 Live loads 3.8.1 General The live load models specified in Clauses 3.8.2 to 3.8.12 shall apply to all span ranges.

3.8.2 Design lanes The number of design lanes for traffic shall be determined from Table 3.4. Each design lane shall have a width, We , of Wc /n.

Table 3.4 Number of design lanes (See Clause 3.8.2.) Deck width, Wc , m

n

6.0 or less Over 6.0 to 10.0 Over 10.0 to 13.5 Over 13.5 to 17.0 Over 17.0 to 20.5 Over 20.5 to 24.0 Over 24.0 to 27.5 Over 27.5

1 2 2 or 3* 4 5 6 7 8

*Both should be checked.

3.8.3 CL-W loading 3.8.3.1 General CL-W loading consists of the CL-W Truck specified in Clause 3.8.3.2 or the CL-W Lane Load specified in Clause 3.8.3.3. A loading of not less than CL-625 shall be used for the design of a national highway network that is generally used for interprovincial transportation. A loading exceeding CL-625 may be specified by a provincial or territorial authority for the design of certain bridges within the province or territory. Loadings lesser or greater than CL-625 shall be used only where justified by traffic conditions and shall require Approval. Alternatively, a traffic load may be based on site-specific vehicle and traffic conditions established by vehicle count load surveys. The resulting level of safety shall be not less than that specified by this Code. Such a loading shall require Approval.

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3.8.3.2 CL-W Truck The CL-W Truck is the idealized five-axle truck shown in Figure 3.2. The W number indicates the gross load of the CL-W Truck in kilonewtons. Wheel and axle loads are shown in terms of W and are also shown for the CL-625 Truck. The wheel spacings, weight distribution, and clearance envelope of the CL-W Truck shall be as shown in Figure 3.2. In Ontario, a CL-625-ONT Truck as specified in Annex A3.4 shall be used. Note: The total load of the CL-625-ONT Truck is 625 kN, but the axle load distribution differs from that shown in Figure 3.2.

The CL-W and the CL-625-ONT Truck shall be placed centrally in a space 3.0 m wide that represents the clearance envelope for each Truck, unless otherwise specified by the Regulatory Authority or elsewhere in this Code. Axle no. CL-W CL-625

1 0.04W 0.08W

3 2 0.1W 0.1W 0.2W 0.2W

4 0.14W 0.28W

25 50

62.5 62.5 125 125

87.5 175

3.6 m

1.2 m

6.6 m

5 0.12W Wheel loads 0.24W Axle loads 75 150

Wheel loads, kN Axle loads, kN

6.6 m

18 m 0.25 m (Typ.)

0.25 m (Typ.)

0.25 m (Typ.)

2.40 m

1.80 m

0.60 m (Typ.)

Clearance envelope 3.0 m

Curb 0.6 m

1.8 m

0.6 m

Figure 3.2 CL-W Truck (See Clause 3.8.3.2.)

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3.8.3.3 CL-W Lane Load The CL-W Lane Load consists of a CL-W Truck with each axle reduced to 80% of the value specified in Clause 3.8.3.2, superimposed within a uniformly distributed load of 9 kN/m, and 3.0 m wide. The CL-W Lane Load is shown in Figure 3.3. In Ontario, a CL-625-ONT Lane Load as specified in Annex A3.4 shall be used. Uniformly distributed load 9 kN/m 0.032W 0.064W

0.08W 0.16W

3.6 m

0.08W 0.16W

1.2 m

0.112W 0.224W

6.6 m

0.096W Wheel loads 0.192W Axle loads

6.6 m

18 m

Figure 3.3 CL-W Lane Load (See Clause 3.8.3.3.)

3.8.4 Application 3.8.4.1 General



The following requirements shall apply: (a) Truck axles that reduce the load effect shall be neglected. (b) The uniformly distributed portion of the lane load shall not be applied to those parts of a design lane where its application decreases the load effect. (c) For the FLS and for SLS Combination 2, the traffic load shall be one truck only, increased by the dynamic load allowance and placed at the centre of one travelled lane. The lane load shall not be considered. (d) For SLS Combination 1 and for ultimate limit states, the traffic load shall be the truck load increased by the dynamic load allowance or the lane load, whichever produces the maximum load effect. This load shall be positioned longitudinally and transversely within each design lane at a location and in the direction that produces maximum load effect. The truck width shall not project beyond the design lane, except as specified in Clause 3.8.4.3(d). The lane load and the CL-W Truck clearance envelope shall not project beyond the edge of a design lane, except as specified in Clause 3.8.4.4.

3.8.4.2 Multi-lane loading When more than one design lane is loaded, the traffic load shall be multiplied by the applicable modification factor specified in Table 3.5. Design lanes that are loaded shall be selected to maximize the load effect.

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Table 3.5 Modification factor for multi-lane loading (See Clause 3.8.4.2.) Number of loaded design lanes

Modification factor

1 2 3 4 5 6 or more

1.00 0.90 0.80 0.70 0.60 0.55

3.8.4.3 Local components The following requirements shall apply: (a) For components incorporated into decks other than modular expansion joints, e.g., manhole covers and drainage gratings, the axle load considered shall be axle no. 2 of the CL-W Truck. (b) For modular expansion joints, the axle load considered shall be axle no. 4 of the CL-W Truck. (c) For decks and other components whose design is governed by the axle loads, the tandem axle, comprising axles nos. 2 and 3 of the CL-W Truck, or axle no. 4 of the CL-W Truck, whichever produces larger effects, shall be considered. (d) In the design lane adjacent to a curb, railing, or barrier, the minimum distance from the centres of the wheels to the curb, railing, or barrier wall shall be 0.30 m. Note: The axle numbers are shown in Figure 3.2.

3.8.4.4 Wheels on the sidewalk When sidewalks and other areas adjacent to a roadway are separated from it only by curbs and not by a traffic barrier, local responses shall be computed by considering a CL-W Truck with each axle load reduced to 70% and with its wheel centres not less than 0.30 m from the face of the railing or barrier on the outer edge. This requirement shall apply only at the ultimate limit states and shall not apply to longitudinal effects in slab bridges or to main girders.

3.8.4.5 Dynamic load allowance 3.8.4.5.1 General A dynamic load allowance shall be applied to the CL-W Truck, or any part of the truck specified in Clause 3.8.3.2, unless otherwise specified by the Regulatory Authority or elsewhere in this Code. A dynamic load allowance shall not be applied to the CL-W Lane Load specified in Clause 3.8.3.3, including that part of the CL-W Lane Load represented by axle loads. A dynamic load allowance shall be included in loads on the superstructure and loads transferred from the superstructure to the substructure, but shall not be included in loads transferred to footings that are surrounded with earth or to those parts of piles that are below ground. A dynamic load allowance shall increase the truck loads by the proportion of the load specified in this Section unless alternative values based on tests or dynamic analysis are Approved.

3.8.4.5.2 Buried structures The dynamic load allowance for loads on arch-type buried structures with a depth of earth cover, DE , between the riding surface and the highest point of the structure shall be 0.40(1 – 0.5DE ), but not less than 0.10. The dynamic load allowance for box-type buried structures shall be the value obtained from Clause 3.8.4.5.3 multiplied by the factor (1 – 0.5DE ), but not less than 0.10.

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3.8.4.5.3 Components other than buried structures For components other than buried structures, the dynamic load allowance shall be (a) 0.50 for deck joints; (b) 0.40 where only one axle of the CL-W Truck is used (except for deck joints); (c) 0.30 where any two axles of the CL-W Truck, or axles nos. 1 to 3, are used; or (d) 0.25 where three axles of the CL-W Truck, except for axles nos. 1 to 3, or more than three axles, are used. Note: The axle numbers are shown in Figure 3.2.

3.8.4.5.4 Reduction for wood components For wood components, the dynamic load allowance specified in Clauses 3.8.4.5.2 and 3.8.4.5.3 shall be multiplied by 0.70.

3.8.5 Centrifugal force For structures on horizontal curves, the centrifugal force shall be computed by multiplying CL-W Truck loads, without dynamic load allowance, by v 2/127r, which shall be taken as non-dimensional. The centrifugal force shall be applied horizontally at the centre of each design lane, at right angles to the direction of travel, and 2.0 m above the deck surface.

3.8.6 Braking force Braking force shall be considered only at the ultimate limit states. Braking force shall be an equivalent static force of 180 kN plus 10% of the uniformly distributed load portion of the lane load from one design lane, irrespective of the number of design lanes, but not greater than 700 kN in total. The braking force shall be applied at the deck surface.

3.8.7 Curb load Curb load shall be considered only at the ultimate limit states. For continuously supported curbs, the design load shall be a uniformly distributed lateral load of 20 kN/m. For curbs supported at discrete points, the design load shall be a concentrated lateral load of 32 kN. Curb loads shall be applied at the top of the curb or 250 mm above the deck surface, whichever is lower.

3.8.8 Barrier loads 3.8.8.1 Traffic barriers The transverse, longitudinal, and vertical loads shall be as specified in Table 3.6 and shall be applied simultaneously, as specified in Clause 12.4.3.5. These loads shall be used for the design of traffic barrier anchorages and decks only. Performance levels are defined in Clause 12.4.3.2.1. The barrier loads on railings shall not be considered to act simultaneously with the curb load or with the wheel loads positioned as specified in Clauses 3.8.4.1(a) and 3.8.4.4. A dynamic load allowance shall not be applied to these loads on barriers.

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Table 3.6 Loads on traffic barriers (See Clause 3.8.8.1.) Performance level

Transverse load, kN

Longitudinal load, kN

Vertical load, kN

PL-1 PL-2 PL-3

50 100 210

20 30 70

10 30 90

3.8.8.2 Pedestrian and bicycle barriers The load on pedestrian and bicycle barrier railings shall be a uniform load of 1.20 kN/m applied laterally and vertically simultaneously.

3.8.9 Pedestrian load For pedestrian bridges and sidewalks on highway bridges, the pedestrian load applied to the walkway area, p, shall be

p = 5 .0 −

s 30

but not less than 1.6 kPa and not greater than 4.0 kPa. For highway bridges with sidewalks, traffic loads in design lanes shall be considered together with the pedestrian load only at the ultimate limit states, with the pedestrian load reduced by 20%. The traffic load specified in Clause 3.8.4.4 and the pedestrian load shall not be considered to act simultaneously on a sidewalk.

3.8.10 Maintenance access loads Maintenance access loads shall be considered only at the ultimate limit states. Service walkways and safety gratings, and the members supporting them, shall be designed for a live load of 1.6 kN uniformly distributed over a rectangular area 1.00 × 0.50 m placed anywhere on the walkway or grating. Manhole steps and ladder rungs shall be designed for a load of 1.0 kN distributed over a length of 100 mm anywhere on the tread area. The tread area shall include all of the horizontal part of the step or rung except parts beyond bends or other features that effectively limit the usable tread length.

3.8.11 Maintenance vehicle load If the width of a sidewalk on a highway bridge, or of a pedestrian bridge, is greater than 3.0 m and access is provided for maintenance vehicles, the maintenance vehicle load shown in Figure 3.4 shall be considered on the walkway area. For sidewalks on a highway bridge, the maintenance vehicle load shall be considered only at the ultimate limit states. The maintenance vehicle load shall not be considered to act simultaneously with the pedestrian live load or with the loading from wheels on the sidewalk specified in Clause 3.8.4.4.

3.8.12 Multiple-use structures Where a highway bridge is used for other purposes, e.g., railway, rail transit, or other utility purposes, the loads and load factors shall be specified by the appropriate Regulatory Authority.

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Wheel loads

12

28 kN

Axle loads

24

56 kN Gross load, 80 kN 2.0 m

CL Axle

CL Axle

0.15 m

1.6 m

0.25 m

Travel 0.15 m

0.3 m

2.2 m truck width

0.25 m

CL Wheel

0.15 m

CL Wheel

Elevation

0.15 m

Plan

Figure 3.4 Maintenance vehicle load (See Clause 3.8.11.)

3.9 Superimposed deformations 3.9.1 General Clause 3.9 specifies requirements related to the effects of temperature changes, shrinkage, creep, thermal gradients through the depth of superstructure, and foundation deformations. These requirements apply to concrete structures, steel structures, and composite structures built from concrete and steel. Analysis of temperature, shrinkage, and creep effects shall not be required for conventional wood structures, but shrinkage and swelling that are perpendicular to the grain and are due to moisture changes shall be considered.

3.9.2 Movements and load effects Provision shall be made for all expansion and contraction that can occur as a result of variations in effective temperature, shrinkage, and creep. All load effects induced by restraint of these dimensional changes, including temporary restraints required during construction, shall be included in the analysis. The effects of concrete creep and shrinkage shall be as specified in Section 8. Temperature differentials and foundation deformation shall be considered when the resulting distortions and displacements or the restraint thereof can cause significant load effects, or where the serviceability of the structure could be affected. When it can be shown that inelastic behaviour reduces the load effects at the ULS and that the structure can sustain such inelastic behaviour, the reduced load effects may be considered.

3.9.3 Superstructure types Temperature effects shall be considered for the following superstructure types: (a) Type A: steel beam, box, or deck truss systems with steel decks, and truss systems that are above the deck;

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(b) Type B: steel beam, box, or deck truss systems with concrete decks; and (c) Type C: concrete systems with concrete decks.

3.9.4 Temperature effects 3.9.4.1 Temperature range The temperature range shall be the difference between the maximum and minimum effective temperatures as specified in Table 3.7 for the type of superstructure. The temperature range shall be modified in accordance with the depth of the superstructure as indicated in Figure 3.5. The maximum and minimum mean daily temperature shall be taken from Figures A3.1.1 and A3.1.2.

Table 3.7 Maximum and minimum effective temperatures (See Clause 3.9.4.1.) Superstructure type (see Clause 3.9.3.) A B

25 °C above maximum mean daily temperature 20 °C above maximum mean daily temperature 10 °C above maximum mean daily temperature

15 °C below minimum mean daily temperature 5 °C below minimum mean daily temperature 5 °C below minimum mean daily temperature

Reduction in maximum effective temperature, °C

M inimum effective temperature

10

Increase in minimum effective temperature, °C

C

Maximum effective temperature

10

5

0

0

1.0 Depth, m

2.0

0

1.0 Depth, m

2.0

5

0

Figure 3.5 Modifications to maximum and minimum effective temperatures (See Clause 3.9.4.1.)

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3.9.4.2 Effective construction temperature In the absence of site-specific data, an effective construction temperature of 15 °C shall be assumed for design. This temperature shall be used to determine the effective temperature ranges for the calculation of expansion and contraction. With Type C structures that are cast in place, the heat of hydration can cause the concrete temperature to be higher than the effective construction temperature at the time of initial set. If more precise data are not available, it shall be assumed that concrete cools by 25 °C from its initial set to the effective construction temperature.

3.9.4.3 Positioning of bearings and expansion joints The Plans shall indicate the positioning of bearings and expansion joints in accordance with Section 11.

3.9.4.4 Thermal gradient effects The effects of thermal gradients through the depth shall be considered in the design of Type A, B, and C structures. A thermal gradient is positive when the top surface of the superstructure is warmer than the bottom surface. The values of temperature differentials are given for Type A and C structures in Figure 3.6. For winter conditions, positive and negative differentials shall be considered. For summer conditions, only positive differentials shall be considered. For composite and non-composite Type B structures, a positive temperature differential decreasing linearly by 30 °C from the top to the bottom of the deck slab shall be considered. The temperature shall be assumed to remain constant throughout the beam or truss below the slab. It shall not be necessary to consider negative differentials. Allowances shall be made for the stresses and deformations induced when the coefficients of thermal expansion of the materials used in a composite structure differ.

3.9.4.5 Thermal coefficient of linear expansion The thermal coefficient of linear expansion shall be as specified in Section 8 for concrete and Section 10 for steel.

Temperature differential, DT, °C

15 Summer conditions — positive temperature differential 10 Winter conditions — positive or negative temperature differential

5

0

0

1.0

2.0

Depth, m

Figure 3.6 Temperature differentials for Type A and C superstructures (See Clause 3.9.4.4.)

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3.10 Wind loads 3.10.1 General 3.10.1.1 General Clause 3.10 specifies design wind loads for all highway structures and provides specific requirements for bridge substructures and superstructures. Guidance for determining the tendency toward aeroelastic instability in wind-sensitive bridges is also provided. All wind loads based on the reference wind pressure, q, shall be treated as equivalent static loads. Special requirements for wind tunnel testing are specified in Clause 3.10.5, with reference to the determination of specific load factors to replace those specified in Table 3.1 for wind load effects. Annex A3.2 specifies requirements for wind loads on highway accessory supports, barriers, and slender structural elements, including the effects of vortex shedding.

3.10.1.2 Reference wind pressure The hourly mean reference wind pressure, q, shall be as specified in Table A3.1.1 for a return period of (a) 100 years for bridge structures with any span 125 m long or longer; (b) 50 years for bridge structures with a maximum span shorter than 125 m, luminaire support structures higher than 16 m, and overhead sign structures; (c) 25 years for luminaire and traffic signal support structures 16 m high or shorter, and for barriers; and (d) 10 years for roadside sign structures where a long life expectancy is not required, or for any of the structures specified in Items (a) to (c) during construction. If the topography at the structure site can cause funnelling of the wind, the reference wind pressure shall be increased by 20%.

3.10.1.3 Gust effect coefficient For highway bridges that are not sensitive to wind action (which includes most bridges of spans less than 125 m except those that are cable supported), the gust effect coefficient, Cg , shall be taken as 2.0. For slender, lighter structures, e.g., pedestrian bridges, luminaire, sign, and traffic signal supports, barriers, and slender structural elements, Cg shall be taken as 2.5. For structures that are sensitive to wind action, the gust factor approach shall not be used and the wind loads shall be determined on the basis of a detailed analysis of dynamic wind action, using an Approved method that includes the effects of buffeting.

3.10.1.4 Wind exposure coefficient The wind exposure coefficient, Ce , shall not be less than 1.0 and shall be taken from Table 3.8 or calculated as (0.10H)0.2, where H is the height above ground of the top of the superstructure. For luminaire, sign, and traffic signal supports, and for barriers, H shall be taken to the top of the standard, support, or structure considered. The height above ground shall be measured from the foot of cliffs, hills, or escarpments when the structure is located in uneven terrain, or from the low water level for structures over water.

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Table 3.8 Wind exposure coefficient, Ce (See Clause 3.10.1.4.) Height above ground of the top of the superstructure, H, m

Wind exposure coefficient, Ce

0 to 10 Over 10 to 16 Over 16 to 25 Over 25 to 37 Over 37 to 54 Over 54 to 76 Over 76 to 105

1.0 1.1 1.2 1.3 1.4 1.5 1.6

3.10.1.5 Non-uniform loading Wind loads shall be applied uniformly or non-uniformly over the entire structure, whichever produces the more critical effects. Unless an analysis of non-uniform wind loads specific to the structure is undertaken, the non-uniform loading shall be 0.75 times the effective uniformly distributed load over any portion of the structure and the full effective uniformly distributed load applied over the remaining portion.

3.10.1.6 Overturning and overall stability When the prescribed loads in the design of members are being applied, overturning, uplift, and lateral displacement shall be considered.

3.10.1.7 Alternative methods When Approved, representative wind tunnel tests or more detailed methods of analysis may be used to establish load coefficients or design criteria different from those specified in this Section. Wind loads derived from the results ofwind tunnel tests shall be used with wind load factors determined in accordance with Clause 3.10.5.2.

3.10.2 Design of the superstructure 3.10.2.1 General The superstructure shall be designed for wind-induced vertical and horizontal drag loads acting simultaneously. The assumed wind direction shall be perpendicular to the longitudinal axis for a straight structure or to an axis chosen to maximize wind-induced effects for a structure curved in plan. 

3.10.2.2 Horizontal drag load The following wind load per unit exposed frontal area of the superstructure shall be applied horizontally: Fh = q CeCgCh where q, Ce , and Cg are as specified in Clauses 3.10.1.2, 3.10.1.4, and 3.10.1.3, respectively, and Ch = 2.0. In the case of truss spans, this load shall be taken to act on the windward truss simultaneously with a load on the leeward truss equal to the load on the windward truss in the through-trusses and 75% of the load on the windward truss in other trusses unless a recognized method is used to calculate the shielding effect of the windward truss.

3.10.2.3 Vertical load The following wind load per unit exposed plan area of the superstructure shall be applied vertically: Fv = q CeCgCv

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where q, Ce , and Cg are as specified in Clauses 3.10.1.2, 3.10.1.4, and 3.10.1.3, respectively, and Cv = 1.0. The vertical load shall be taken to act either upwards or downwards. In addition to the application of Fv as a uniformly distributed load over the whole plan area, the effect of possible eccentricity in the application of the load shall be considered. For this purpose, the same total load shall be applied as an equivalent vertical line load at the windward quarter point of the transverse superstructure width.

3.10.2.4 Wind load on live load The horizontal wind load per unit exposed frontal area of the live load shall be calculated in accordance with Clause 3.10.2.2, except that Ch shall be taken as 1.2. The exposed frontal area of the live load shall be the entire length of the superstructure, as seen in elevation in the direction of the wind as specified in Clause 3.10.2.1, or any part or parts of that length producing critical response, multiplied by a height of 3.0 m above the roadway surface for vehicular bridges and 1.5 m for pedestrian bridges. Areas below the top of a solid barrier wall shall be neglected.

3.10.3 Design of the substructure 3.10.3.1 General The substructure shall be designed for wind-induced loads transmitted to it from the superstructure and for wind loads acting directly on the substructure. Loads for wind directions both normal to and skewed to the longitudinal centreline of the superstructure shall be considered.

3.10.3.2 Wind loads transmitted from the superstructure The horizontal drag load specified in Clause 3.10.2.2 shall be resolved into transverse and longitudinal components using the skew angle modification coefficients specified in Table 3.9. These loads shall be applied as equivalent horizontal line loads at the elevation of the centroid of the exposed frontal area of the superstructure. The vertical load specified in Clause 3.10.2.3, modified for skew angle using appropriate coefficients from Table 3.9, shall be applied as an upward or downward line load along the centreline of the superstructure or along the windward quarter point, whichever produces the more critical effect. The vertical load and the longitudinal and transverse horizontal loads shall be applied simultaneously and the combination leading to maximum load effects in the substructure shall be used. The requirements of Clause 3.10.2.4 shall apply in determining the wind load on the live load that is to be transferred to the substructure. The modifications specified for “Other spans” in Table 3.9 shall apply to skewed wind loads on the live load on any type of span. Longitudinal loads shall be determined for winds parallel to the longitudinal axis of the bridge (i.e., at a skew angle of 90°) using the projected area to the wind of the bridge superstructure in the longitudinal direction.

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Table 3.9 Modification of wind loads on superstructure with skew angle (See Clause 3.10.3.2.) Modification coefficients Skew angle (measured from a line normal to the longitudinal axis), degrees 0 15 30 45 60

Truss spans

Other spans

Transverse horizontal or vertical load

Longitudinal horizontal load

Transverse horizontal or vertical load

Longitudinal horizontal load

1.00 0.93 0.87 0.63 0.33

0.00 0.16 0.37 0.55 0.67

1.00 0.88 0.82 0.66 0.34

0.00 0.12 0.24 0.32 0.38

3.10.3.3 Loads applied directly to substructure The substructure shall be designed for directly applied horizontal drag loads. The wind load on a unit frontal exposed area of the substructure shall be calculated in accordance with Clause 3.10.2.2. The horizontal drag coefficient, Ch , shall be taken as 0.7 for circular piers, 1.4 for octagonal piers, and 2.0 for rectangular and square piers. For wind directions skewed to the substructure, the loads shall be resolved into components taken to act perpendicularly to the end and side elevations of the substructure. These load components shall be assumed to act horizontally at the centroids of the exposed areas of the end and side elevations and shall be applied simultaneously with the loads transmitted from the superstructure.

3.10.4 Aeroelastic instability 3.10.4.1 General Aeroelastic instability, in which the motion of the structure in wind produces aerodynamic forces augmenting such motion, shall be taken into account in the design of bridges and structural components apt to be wind sensitive. The aeroelastic phenomena of vortex shedding, galloping, flutter, and divergence shall be considered where applicable.

3.10.4.2 Criterion for aeroelastic instability For a wind-sensitive structure affected by the wind actions specified in Clause 3.10.4.1, it shall be shown that the performance of the structure without further application of load factors is acceptable up to a wind speed higher than the reference wind speed, Vref . Unless alternative rational procedures are available, the reference wind speed shall be taken as

Vref = 1.24 a w qCe where

α w = the load factor for wind specified in Clause 3.5.1 The reference wind velocity shall be taken at deck height. Bridges and their structural components, including cables, shall be designed to be free of fatigue damage due to vortex-induced or galloping oscillations.

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3.10.5 Wind tunnel tests 3.10.5.1 General Structures that are sensitive to wind include those that are flexible, slender, lightweight, long span, or of unusual geometry. For such structures, supplementary studies by an expert in the field should be conducted, and it is possible that wind tunnel tests will be required. Representative wind tunnel tests may be used to satisfy the requirements of Clauses 3.10.4.1 and 3.10.4.2. These tests may also be used to establish the components of the overall structural loads specified in Clauses 3.10.2 and 3.10.3. 

3.10.5.2 Load factors If the overall structural loads due to wind are determined using wind tunnel tests, the load factor for wind,  w , in ULS Combination 4 shall be calculated as

a w = 0.80d w exp (3.5kVw ) where k

=

Vw2

0.152 + Vw2

The bias coefficient,  w , and coefficient of variation, Vw , of the wind load effect shall be determined by the persons responsible for the wind tunnel tests and shall account for the bias and uncertainty of the reference wind pressure, the gust, the pressure and exposure coefficients, and the uncertainty of the modelling. Wind load factors for design in the ULS Combination 3 and ULS Combination 7 shall be the product of the factor specified in Table 3.1 and the ratio ( w / 1.50).

3.11 Water loads 3.11.1 General Local conditions at the site shall be considered in all cases.

3.11.2 Static pressure Static water pressure shall be assumed to act perpendicular to the surface that is retaining the water. The pressure of water at a specific point shall be calculated as the product of the height of water above that point and the density of water.

3.11.3 Buoyancy The effects of immersion in water or exposure to water pressure shall be considered. The beneficial effects of buoyancy shall be included, provided that they are always in existence. The non-beneficial effects of buoyancy shall be included unless the possibility of their occurrence can be excluded with certainty. Buoyancy shall be taken as the vertical components of the static forces as calculated in accordance with Clause 3.11.2. Buoyancy shall be considered as an uplift force equivalent to the volume of water displaced.

3.11.4 Stream pressure 3.11.4.1 Longitudinal effects The load due to flowing water acting longitudinally on a substructure element, P, shall be taken as CDAv 2/2, where the longitudinal drag coefficient, CD , is as specified in Table 3.10.

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Table 3.10 Longitudinal drag coefficient, CD (See Clause 3.11.4.1.)

Upstream shape of pier

Longitudinal drag coefficient, CD

Semi-circular nosed Square ended Wedge nosed at 90° Pier with debris lodged

0.7 1.4 0.8 1.4

3.11.4.2 Lateral effects

The lateral load due to water flowing at angle,  , against a substructure element, Pp , shall be taken as CL HLv 2/2, where the lateral load coefficient, CL , is as specified in Table 3.11.

Table 3.11 Lateral load coefficient, CL (See Clause 3.11.4.2.) Angle,  , between direction of flow and longitudinal pier axis, degrees

Lateral load coefficient, CL

0 5 10 20 30

0.0 0.5 0.7 0.9 1.0

3.11.5 Wave action Force effects due to wave action on bridge substructure elements exposed to environments where significant wave action can occur shall be evaluated in accordance with site-specific conditions. In the absence of such evaluations, the force against a flat surface substructure element, Fw , due to wave action, as a function of the wave height, Hw , shall be taken as 10Hw2. Fw shall be considered to act at mid-height of the wave, Hw /2, above the still water elevation. For aerodynamically curved frontal surfaces, a value of Fw /2 shall be used.

3.11.6 Scour action Local conditions and past records of floods shall be consulted in designing foundation elements when scour is expected to occur. The requirements of Sections 1 and 6 shall be applied. Changes in foundation conditions resulting from the design flood shall be considered at serviceability and ultimate limit states.

3.11.7 Debris torrents Debris torrent loads shall be considered on exposed superstructures and substructures in accordance with site-specific conditions. Sites subject to heavy rainfall of short duration, earthquakes, landslides, and rockfalls shall be investigated for debris torrents when the following conditions exist: (a) the creek channel gradient is greater than 25° for an extended length along the channel profile; (b) boulders and debris exist in the channel; (c) there is a history of such events. An expert in the field shall be consulted to determine debris torrent loads.

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3.12 Ice loads 3.12.1 General Clause 3.12 refers only to freshwater ice in rivers and lakes. For ice loads in sea water, specialist advice shall be sought. Ice forces on bridge substructure elements shall be determined by considering the prevailing site conditions and expected form of ice action. The following interaction modes between ice and structure shall be considered: (a) dynamic forces due to collision of moving ice sheets or floes carried by the stream current or driven by wind action (both horizontal and vertical components shall be considered); (b) static forces due to thermal movements of continuous stationary ice sheets; (c) lateral thrust due to arching action resulting from ice dams and ice jams; and (d) static or dynamic vertical forces along the substructure element due to the effects of fluctuating water levels or the dynamic effects of colliding ice floes. Data related to the anticipated thickness of ice, its direction of movement, its speed of impact, and the height of its action on the substructure element shall be obtained or derived from field surveys and records of measurements made at or near the site.

3.12.2 Dynamic ice forces 3.12.2.1 Effective ice strength Unless more precise data is available, the following values for the effective crushing strength of ice, p, shall be used: (a) the ice breaks up at melting temperature and is substantially disintegrated: 400 kPa; (b) the ice breaks up at melting temperature and is somewhat disintegrated: 700 kPa; (c) the ice breaks up or ice movement occurs at melting temperature and is internally sound and moving in large pieces: 1100 kPa; and (d) the ice breaks up or ice movement occurs at temperatures considerably below the melting point or the ice: 1500 kPa. 

3.12.2.2 Dynamic ice force on a pier 3.12.2.2.1 General The horizontal dynamic ice force on a pier shall be determined in accordance with Clause 3.12.2.2.3 using the ice failure forces in accordance with Clause 3.12.2.2.2.

3.12.2.2.2 Ice failure forces Ice failure forces shall be determined as follows: (a) Bending force, Fb: Fb = Cn pt2 where Cn = 0.5 tan ( + 15°), with  as shown in Figure 3.7 (b) Crushing force, Fc: Fc = Ca ptw where

t +1 w (c) Bending/crushing transition force Fbc: Ca

=

5

(

)

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3.12.2.2.3 Horizontal dynamic ice, force, F The horizontal force, F, due to the pressure of moving ice shall be taken as, when Fc  Fb: F = Fc when Fc  Fb: F = Fc if Fbc  Fc F = Fb if Fbc  Fb F = Fbc if Fc  Fbc > Fb In small streams where it is unlikely that large-size ice floes will form, the force, F, may be reduced by up to 50% of the value in accordance with this Clause.

a Flow

b

Figure 3.7 Pier nose angle and subtended nose angle for calculating forces due to moving ice (See Clauses 3.12.2.2 and 3.12.2.3.1.)

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3.12.2.3 Ice impact forces 3.12.2.3.1 Piers parallel to flow Where the longitudinal axis of the pier is reasonably parallel to the direction of the movement of ice, the force, F, as derived from Clause 3.12.2.2, shall be considered to act along the longitudinal axis of the pier. The following design cases shall be investigated: (a) case 1: a longitudinal force, F, plus a transverse force, 0.15F ; and (b) case 2: a longitudinal force, 0.5F, plus a transverse force, Ft , where

Ft =

F 2 tan(0.5b + qf )

In the absence of more precise data,  f shall be taken as 6°. For a round-nosed edge,  shall be taken as 100°, where  is as shown in Figure 3.7.

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3.12.2.3.2 Piers skewed to flow For piers with their longitudinal axis at an angle to the direction of flow, the total collision forces shall be considered to act on the projected pier width and resolved into components parallel and perpendicular to the pier shaft. The component that acts transversely on the pier shaft shall not be taken as less than 20% of the total force.

3.12.2.4 Slender piers Where ice forces are significant, slender and flexible piers and their components, e.g., piles exposed to ice action, shall be used only when a specialist on the mechanics of ice and structure interaction is consulted.

3.12.3 Static ice forces Where ice sheets are exposed to non-uniform thermal stresses and strains relative to the pier due to unbalanced freezing, the resulting forces on the piers shall be calculated using a compressive crushing strength of ice of not less than 1500 kPa when the ice temperature is significantly below the freezing point.

3.12.4 Ice jams For clear openings of less than 30 m between piers or between a shoreline and a pier located in bodies of water where floating ice can occur, a pressure of 10 kPa shall be considered to act against the exposed substructure element. This force shall be applied above the level of still water for the expected thickness of the ice jam, both laterally and in the direction of the ice flow. For clear openings of more than 30 m, this force may be reduced to 5 kPa against the exposed faces.

3.12.5 Ice adhesion forces The vertical force due to water level fluctuations, Fv , on a pier frozen to an ice formation shall be calculated as follows: (a) for circular piers: Fv = 1250t 2(1.05 + 0.13R/t 0.75); and (b) for oblong piers: Fv = 15Lpt 1.25 + 1250t 2(1.05 + 0.13R/t 0.75).

3.12.6 Ice accretion 3.12.6.1 General Ice accretion loads shall be taken to occur on all exposed surfaces of superstructure members, structural supports, traffic signals, luminaires, and railings. In the case of sign panels, bridge girders, and solid barriers, ice accretion shall be considered to occur on one side only.

3.12.6.2 Load effect The design ice thickness for ice accretion shall be the value specified in Figure A3.1.4. A unit weight of 9.8 kN/m3 shall be used in calculating ice accretion loads.

3.13 Earthquake effects Requirements for calculating effects due to earthquake forces are specified in Section 4. Relevant data pertaining to seismic zones, velocities, and accelerations are provided in Table A3.1.1 and Figures A3.1.6 and A3.1.7. Load combinations and load factors are specified in Table 3.1.

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3.14 Vessel collisions 3.14.1 General In a navigable waterway crossing where there is a risk of vessel collision, all bridge elements that could be hit shall be designed for vessel impact or adequately protected from vessel collision. The design procedure for vessel collision shall be as specified in Annex A3.3. The following general requirements shall apply: (a) In navigable waterways where vessel collision is possible, structures shall be (i) designed to resist the design vessel collision forces; (ii) evaluated to meet a minimum level of safety; or (iii) adequately protected by fenders, dolphins, berms, islands, or other devices, as appropriate. (b) Consideration shall be given to the relationship of the bridge (including its structural dynamic response) to the following: (i) waterway geometry; (ii) size, type, loading condition, and frequency of vessels using the waterway; (iii) navigable water depth; and (iv) vessel speed and direction.

3.14.2 Bridge classification Bridges shall be classified as follows: (a) Class I: bridges that are of critical importance, including those that have to remain open to all traffic after a vessel collision. (b) Class II: bridges that are of regular importance, including those that have to remain open to emergency and security vehicles after a vessel collision.

3.14.3 Assessment Two methods, specified in Annex A3.3, may be used for assessing the classification criteria, the selection of the design vessel, and the calculation of the vessel collision forces. Method I is a simplified approach. Method II is a probabilistic approach based on AFmax , the maximum annual frequency of collapse for the whole bridge.

3.14.4 Annual frequency of collapse The annual frequency of collapse, AF, for each pier and span component susceptible to ship collision shall be determined by distributing the total bridge acceptance criterion, AFmax , over the number of piers and span components located in the navigable waterway.

3.14.5 Design vessel 3.14.5.1 Frequency distribution The number of vessels, N, passing under the bridge shall be developed for each pier and span component being evaluated in accordance with the size, type, and loading condition of the vessels and the depth of navigable water.

3.14.5.2 Selection For Method I, the selection of the design vessel shall be based solely on the frequency distribution of vessel traffic. For Method II, a design vessel for each pier or span component shall be selected, such that the estimated annual frequency of collapse due to vessels equal to and larger than the design vessel is less than the maximum permitted annual frequency, AFmax .

3.14.6 Application of collision forces Forces shall be applied as equivalent static forces for superstructure and pier design (see Annex A3.3).

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3.14.7 Protection of piers Protection may be provided to reduce or eliminate the exposure of bridge piers to vessel collision. Physical protection systems may include fenders, pile clusters, pile-supported structures, dolphins, islands, and combinations thereof. Such protection systems shall be considered sacrificial and be capable of stopping the vessel before contact with the pier or redirecting the vessel away from the pier.

3.15 Vehicle collision load Highway bridge piers located less than 10 m from the edge of the road pavement shall be designed for a collision load equivalent to a horizontal static force of 1400 kN. The collision load shall be applied horizontally 1.20 m above ground level at the pier, and at 10° to the direction of travel.

3.16 Construction loads and loads on temporary structures 3.16.1 General The weights of materials, workers, and equipment supported during construction shall be considered dead loads or live loads in accordance with Clauses 3.16.2 and 3.16.3. The possibility of occurrence of loads due to wind, ice, and stream flow shall be determined in accordance with the expected life of the structure or the duration of the construction stage considered. A ten-year return period shall be used for these loads when they are applied.

3.16.2 Dead loads Dead loads shall include the weights of formwork, falsework, fixed appendages, stored material, and lifting and launching devices, or parts thereof, that are not subject to movement during the construction stage considered.

3.16.3 Live loads Live loads shall include the weights of workers, vehicles, hoists, cranes, other equipment, and structural components that are subject to movement during the construction stage considered. The live load factor to be used for construction live loads shall be 85% of the value specified for L in Table 3.1.

3.16.4 Segmental construction 3.16.4.1 Erection loads Erection loads assumed in design shall be shown on the Plans. Erection loads shall include all induced forces due to the anticipated system of temporary works, erection equipment, construction sequence, and closure forces due to misalignment corrections. Consideration shall be given to the effects of any changes to the statics of the structural system occurring during construction and the imposition, change, and removal of any temporary supports, erection equipment, or assumed loads, including residual built-in forces, deformations, post-tensioning effects, creep, shrinkage, and thermal and any other strain-induced effects.

3.16.4.2 Construction live loads Except for bridges constructed by incremental launching, a uniformly distributed load of not less than 500 Pa over the constructed deck area of the bridge shall be considered, to allow for the weight of miscellaneous equipment and machinery. For balanced cantilever construction, the load shall be not less than 500 Pa on one cantilever and shall be 250 Pa on the other.

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Consideration shall be given to all loads from special construction equipment such as a form traveller, launching gantry or truss, lifting winch or crane, or segment delivery truck and to the static and dynamic force effects produced during segment lifting. The Plans shall require that the actual loads be obtained from the manufacturers of the equipment and Approved before construction. Forces due to acceleration and slippage during lifting shall be considered. An equivalent static load increment equal to at least 10% of the weight of the segment and attachments shall be assumed. When accelerations are not accurately predictable and controllable, an equivalent static load increment of 100% shall be assumed. Horizontal forces due to braking or acceleration of mobile construction equipment shall be considered in the design. Such forces shall be at least 2% of the total weight of the equipment.

3.16.4.3 Incremental launching Incrementally launched bridges shall be designed to resist the effects of bearing construction tolerances and friction on launching bearings. When inclined launching bearings are used (as opposed to permanent horizontal bearings) the additional forces at the launching jacks and the piers shall be considered. The coefficient of friction on launching bearings made of polished stainless steel sliding on lubricated polytetrafluoroethylene (PTFE) in compliance with Section 11 shall be assumed to vary between zero and 0.04, whichever governs holdback or pushing forces.

3.16.5 Falsework Falsework shall be designed and detailed in accordance with CSA S269.1.

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Annex A3.1 (normative) Climatic and environmental data Notes: (1) This Annex is a mandatory part of this Code. (2) See Annex CA3.1 of CSA S6.1 for the sources and derivation of the data presented in this Annex.

Table A3.1.1 Reference wind pressure and seismic zoning (See Clauses 3.10.1.2, 3.13, and 4.4.3.)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

415 570 470 280 220 305 285 455 245 225 320 475 360 445 445 225 225 485 310 310 485 270 325 210 305 240 270 265 285 360 405 305 225 340 225 380 380 360

530 675 560 340 265 355 340 560 315 285 370 605 420 555 555 280 280 565 365 365 565 355 410 255 350 285 310 345 375 420 525 360 275 410 280 440 440 420

620 755 630 385 300 390 380 640 375 335 405 715 470 645 645 325 325 625 400 400 625 425 480 285 385 315 345 415 445 470 625 405 320 470 325 485 485 470

710 840 700 430 340 430 430 720 440 390 440 830 520 740 740 370 370 690 440 440 690 500 550 310 420 350 380 480 520 520 730 450 360 530 370 520 520 520

4 3 5 2 1 3 2 6 1 1 1 4 4 6 6 1 1 5 1 2 5 1 1 1 1 1 1 1 1 4 3 1 1 1 1 4 4 4

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

0.20 0.15 0.30 0.10 0.05 0.15 0.10 0.40 0.05 0.05 0.05 0.20 0.20 0.40 0.40 0.05 0.05 0.30 0.05 0.10 0.30 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.20 0.15 0.05 0.05 0.05 0.05 0.20 0.20 0.20

4 3 5 1 0 1 1 6 1 1 0 4 — 6 6 1 1 5 0 1 5 1 1 0 0 1 1 1 1 — 3 1 1 1 1 2 2 —

0.20 0.15 0.30 0.05 0.00 0.05 0.05 0.40 0.05 0.05 0.00 0.20 — 0.40 0.40 0.05 0.05 0.30 0.00 0.05 0.30 0.05 0.05 0.00 0.00 0.05 0.05 0.05 0.05 — 0.15 0.05 0.05 0.05 0.05 0.10 0.10 —

British Columbia



Abbotsford Agassiz Alberni Ashcroft Beatton River Burns Lake Cache Creek Campbell River Carmi Castlegar Chetwynd Chilliwack Cloverdale Comox Courtenay Cranbrook Crescent Valley Crofton Dawson Creek Dog Creek Duncan Elko Fernie Fort Nelson Fort St. John Glacier Golden Grand Forks Greenwood Haney Hope Kamloops Kaslo Kelowna Kimberley Kitimat Plant Kitimat Townsite Langley

(Continued)

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Table A3.1.1 (Continued) Hourly mean wind pressure, Pa, for return periods of Location

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

British Columbia (continued) Lillooet Lytton Mackenzie Masset McBride McLeod Lake Merritt Mission City Montrose Nakusp Nanaimo Nelson New Westminster North Vancouver Ocean Falls 100 Mile House Osoyoos Penticton Port Alberni Port Hardy Port McNeill Powell River Prince George Prince Rupert Princeton Qualicum Beach Quesnel Revelstoke Richmond Salmon Arm Sandspit Sidney Smithers Smith River Squamish Stewart Taylor Terrace Tofino Trail Ucluelet Vancouver Vernon Victoria Williams Lake Youbou

315 310 245 490 275 245 315 465 215 235 470 225 360 360 465 300 300 395 470 485 485 420 280 420 240 460 250 240 360 285 535 460 315 210 380 325 315 270 540 260 540 360 315 475 295 460

380 380 285 565 315 285 380 580 285 285 560 280 420 430 535 355 405 505 560 565 565 530 335 485 310 560 285 285 430 340 615 535 365 255 480 380 365 330 615 315 315 430 380 560 340 535

430 435 315 625 350 315 430 675 340 330 635 325 470 480 595 390 495 590 630 625 625 620 370 535 365 640 310 315 480 380 680 595 400 285 560 425 400 360 675 350 675 480 430 630 375 595

490 490 350 690 380 350 490 770 410 370 710 370 520 530 650 430 590 680 700 660 680 710 410 590 420 720 340 350 530 430 740 660 440 310 650 480 440 400 740 390 740 530 490 690 410 660

2 2 2 6 1 2 2 4 1 1 4 1 4 4 4 1 1 1 5 6 6 5 2 5 2 4 2 1 4 1 6 5 3 2 3 4 1 4 5 1 5 4 1 5 2 4

0.10 0.10 0.10 0.40 0.05 0.10 0.10 0.20 0.05 0.05 0.20 0.05 0.20 0.20 0.20 0.05 0.05 0.05 0.30 0.40 0.40 0.30 0.10 0.30 0.10 0.20 0.10 0.05 0.20 0.05 0.40 0.30 0.15 0.10 0.15 0.20 0.05 0.20 0.30 0.05 0.30 0.20 0.05 0.30 0.10 0.20

1 2 0 6 0 0 1 4 1 1 4 1 — — 2 1 1 1 5 6 6 5 0 3 2 4 0 1 — 1 6 5 1 1 3 2 0 2 5 1 5 4 1 6 1 4

0.05 0.10 0.00 0.40 0.00 0.00 0.05 0.20 0.05 0.05 0.20 0.05 — — 0.10 0.05 0.05 0.05 0.30 0.40 0.40 0.30 0.00 0.15 0.10 0.20 0.00 0.05 — 0.05 0.40 0.30 0.05 0.05 0.15 0.10 0.00 0.10 0.30 0.05 0.30 0.20 0.05 0.40 0.05 0.20

305 390 315

360 440 380

405 485 430

450 520 490

1 1 1

0.05 0.05 0.05

0 0 0

0.00 0.00 0.00

Alberta Athabasca Banff Barrhead

(Continued)

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Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

275 395 395 315 300 740 655 310 535 235 730 315 315 365 305 265 270 315 215 370 210 240 510 365 210 310 300 640 215 395 235 310 705 235 310 330

320 460 455 380 360 895 770 365 665 305 880 380 390 415 360 310 310 380 255 430 255 305 585 415 255 365 360 745 255 470 285 365 850 285 365 390

360 515 495 430 405 1020 865 400 765 365 1000 430 450 460 405 350 350 435 285 475 285 365 650 455 285 400 405 825 290 535 320 405 965 320 405 435

400 570 540 490 450 1150 960 440 870 430 1130 490 510 500 450 390 380 490 320 520 310 420 720 500 310 440 450 910 320 600 360 440 1080 360 440 480

1 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 1 1 1 1 0 1 1 1 0 1 0 1 0 1 0 0 0 1 1

0.05 0.00 0.05 0.05 0.00 0.00 0.00 0.00 0.05 0.00 0.05 0.00 0.05 0.05 0.00 0.05 0.00 0.05 0.05 0.05 0.05 0.00 0.05 0.05 0.05 0.00 0.05 0.00 0.05 0.00 0.05 0.00 0.00 0.00 0.05 0.05

0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

280 240 320 430 575 510 355 255 230 280 245 300 320 305

330 305 395 510 670 590 415 310 275 330 310 360 380 360

370 365 450 575 745 650 465 355 310 370 360 405 430 405

410 420 510 640 820 710 510 400 340 410 410 450 480 450

1 0 1 0 0 1 1 0 0 1 0 1 1 0

0.05 0.00 0.05 0.00 0.00 0.05 0.05 0.00 0.00 0.05 0.00 0.05 0.05 0.00

0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Alberta (continued) Beaverlodge Brooks Calgary Campsie Camrose Cardston Claresholm Cold Lake Coleman Coronation Cowley Drumheller Edmonton Edson Embarras Portage Fairview Fort McMurray Fort Saskatchewan Fort Vermilion Grande Prairie Habay Hardisty High River Jasper Keg River Lac LaBiche Lacombe Lethbridge Manning Medicine Hat Peace River Penhold Pincher Creek Ranfurly Red Deer Rocky Mountain House Slave Lake Stettler Stony Plain Suffield Taber Turner Valley Valleyview Vegreville Vermilion Wagner Wainwright Wetaskiwin Whitecourt Wimborne

(Continued) November 2006

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Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

440 490 475 320 280 395 420 280 290 330 315 450 295 470 365 260 320 360 270 450 265 340 340 470 360 435 335 455 330 385 315

510 585 580 380 330 460 495 330 350 390 365 560 360 560 435 310 365 415 330 590 325 385 385 560 425 555 385 545 390 440 365

570 660 670 425 370 515 560 370 395 440 400 640 410 630 495 355 400 460 375 705 380 420 420 635 480 650 425 620 440 485 400

630 740 760 470 410 570 620 410 440 490 440 730 460 710 550 400 430 510 430 830 440 460 460 710 540 750 460 690 490 530 440

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

305 435 375 480 315 330 300 330 280 330 395 335 285 360 360 310 325 370

360 510 435 570 365 390 360 390 330 390 460 395 340 415 415 365 380 440

405 570 490 645 400 440 410 440 370 440 515 440 380 465 460 400 425 490

450 630 540 720 440 490 450 490 410 490 560 490 430 510 510 440 470 540

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Saskatchewan Assiniboia Battrum Biggar Broadview Dafoe Dundurn Estevan Hudson Bay Humbolt Island Falls Kamsack Kindersley Lloydminster Maple Creek Meadow Lake Melfort Melville Moose Jaw Mipawin North Battleford Prince Albert Qu’Appelle Regina Rosetown Saskatoon Scott Strasbourg Swift Current Uranium City Weyburn Yorkton Manitoba Beausejour Boissevain Brandon Churchill Dauphin Flin Flon Gimli Island Lake Lac du Bonnet Lynn Lake Morden Neepawa Pine Falls Portage la Prairie Rivers Sandilands Selkirk Split Lake

(Continued)

76

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© Canadian Standards Association

Canadian Highway Bridge Design Code

Table A3.1.1 (Continued)

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

350 310 350 295 330 370 350 355 280 350

405 365 405 340 390 440 405 415 330 405

450 405 450 380 440 490 450 460 370 450

500 440 500 420 490 540 510 510 420 490

0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0 0 0 0 0 0 0 0 0 0

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

395 430 305 220 295 305 205 275 200 305 230 210 350 240 320 350 460 260 240 315 310 415 315 385 260 360 315 265 290 215 245 295 310 375 190 320 285 285 330

480 510 360 280 360 360 240 330 235 380 280 280 415 305 380 435 535 315 305 380 365 485 380 460 315 415 365 310 360 280 310 360 380 455 235 380 375 375 410

550 570 400 330 410 400 260 370 260 440 320 330 460 360 430 500 590 350 360 430 400 540 430 520 350 460 400 350 415 335 360 410 435 525 270 430 450 450 475

620 640 450 380 460 450 290 420 290 500 360 390 520 420 480 580 660 390 420 490 440 600 490 595 390 510 440 390 470 390 420 460 500 600 310 480 530 550 600

0 1 2 0 2 1 0 2 0 0 1 1 1 1 1 0 1 1 0 0 0 1 1 1 1 0 0 0 1 0 1 2 1 0 0 0 0 0 0

0.00 0.05 0.10 0.05 0.10 0.05 0.00 0.10 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.05 0.00 0.00 0.00 0.05 0.05 0.00

0 1 4 1 4 — 0 4 0 1 2 1 2 1 1 0 — 1 1 1 1 1 3 1 1 1 — 1 1 — 1 4 1 0 0 0 — 1 0

0.00 0.05 0.20 0.05 0.20 — 0.00 0.20 0.00 0.05 0.10 0.05 0.10 0.05 0.05 0.00 — 0.05 0.05 0.05 0.05 0.05 0.15 0.05 0.05 0.05 — 0.05 0.05 — 0.05 0.20 0.05 0.00 0.00 0.00 — 0.05 0.00

Hourly mean wind pressure, Pa, for return periods of Location

10 yr

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Manitoba (continued) St. Boniface Steinbach St. Vital Swan River The Pas Thompson Transcona Virden Whiteshell Winnipeg Ontario Ailsa Craig Ajax Alexandria Alliston Almonte Ansonville Armstrong Arnprior Atikokan Aurora Bancroft Barrie Barriefield Beaverton Belleville Belmont Bowmanville Bracebridge Bradford Brampton Brantford Brighton Brockville Brooklin Burk’s Falls Burlington Caledonia Cambridge Campbellford Camp Borden Cannington Carleton Place Cavan Centralia Chapleau Chatham Chelmsford Chesley Clinton

(Continued) November 2006

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© Canadian Standards Association

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

260 465 260 440 255 300 350 260 320 330 300 320 200 430 335 310 340 315 230 235 330 290 280 375 250 260 335 390 365 230 350 275 210 310 395 300 205 260 365 250 215 335 315 260 365 335 290 310 200 255 190

315 535 310 510 325 360 415 315 380 410 355 380 235 510 385 380 410 390 275 305 410 360 360 455 310 310 385 460 415 275 415 330 245 380 480 350 240 315 415 295 280 385 380 315 415 410 360 365 245 325 235

350 595 350 565 385 410 465 350 430 480 390 430 260 575 425 435 470 450 310 365 475 415 420 525 355 355 425 520 460 310 465 375 275 435 550 390 260 350 460 325 335 425 435 350 460 475 415 405 280 385 270

390 650 390 620 450 460 520 390 480 550 430 480 290 640 450 500 530 510 340 420 540 470 480 600 410 400 460 580 500 340 520 420 300 490 620 430 290 390 500 360 390 460 490 390 500 540 470 450 320 450 310

1 1 0 1 0 2 0 2 1 0 0 0 0 1 0 0 0 1 0 1 0 1 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 0 1 1 0 0 1 2 0 1 0

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

0.05 0.05 0.05 0.05 0.05 0.10 0.00 0.10 0.05 0.00 0.00 0.00 0.00 0.05 0.05 0.05 0.00 0.05 0.00 0.05 0.00 0.05 0.05 0.00 0.05 0.05 0.05 0.00 0.05 0.00 0.05 0.05 0.00 0.00 0.00 0.00 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.00 0.05 0.00

1 1 1 1 1 4 0 4 1 0 0 0 0 — 1 1 0 1 0 1 0 1 1 0 1 1 1 0 2 0 2 — 0 0 0 0 0 1 1 1 1 — 2 1 1 1 1 4 0 1 0

0.05 0.05 0.05 0.05 0.05 0.20 0.00 0.20 0.05 0.00 0.00 0.00 0.00 — 0.05 0.05 0.00 0.05 0.00 0.05 0.00 0.05 0.05 0.00 0.05 0.05 0.05 0.00 0.10 0.00 0.10 — 0.00 0.00 0.00 0.00 0.00 0.05 0.05 0.05 0.05 — 0.10 0.05 0.05 0.05 0.05 0.20 0.00 0.05 0.00

Ontario (continued) Coboconk Cobourg Cochrane Colborne Collingwood Cornwall Corunna Deep River Deseronto Dorchester Dorion Dresden Dryden Dunbarton Dunnville Durham Dutton Earlton Edison Elmvale Embro Englehart Espanola Exeter Fenelon Falls Fergus Fonthill Forest Fort Erie Fort Frances Gananoque Georgetown Geraldton Glencoe Goderich Gore Bay Graham Gravenhurst Grimsby Guelph Guthrie Hagersville Haileybury Haliburton Hamilton Hanover Hastings Hawkesbury Hearst Honey Harbour Hornepayne

(Continued)

78

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© Canadian Standards Association

Canadian Highway Bridge Design Code

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

260 330 300 330 200 230 295 230 260 400 350 260 295 275 265 240 355 265 330 340 365 395 315 285 205 300 245 255 320 310 260 370 350 260 300 290 260 210 320 460 315 260 330 260 290 375 250 260 430 295 330

315 410 360 380 235 275 360 275 315 480 415 315 360 330 325 285 415 325 410 410 455 480 380 360 240 360 285 325 380 380 315 435 435 315 360 360 315 245 380 535 380 325 380 300 360 435 310 315 510 360 410

350 475 405 425 260 310 410 310 350 545 465 350 410 370 380 315 465 380 475 470 535 555 430 415 260 410 315 385 430 435 350 495 505 350 410 410 350 275 430 595 435 385 425 340 415 490 355 350 575 410 475

390 540 450 470 290 340 460 340 390 620 520 390 460 420 430 350 520 430 540 530 610 630 490 470 290 460 350 450 480 490 390 550 570 390 460 470 390 300 480 650 490 440 470 370 470 540 410 390 640 460 550

1 0 0 0 0 0 2 0 1 0 1 1 1 0 1 0 0 1 0 0 0 0 1 0 0 1 1 1 0 0 1 0 0 0 2 0 1 0 1 1 1 1 0 1 1 0 0 1 1 2 0

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

0.05 0.00 0.05 0.05 0.00 0.00 0.10 0.00 0.05 0.00 0.05 0.05 0.05 0.05 0.05 0.00 0.00 0.05 0.00 0.05 0.00 0.00 0.05 0.05 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.00 0.10 0.05 0.05 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.05

1 0 1 — 0 0 4 0 3 0 2 1 1 1 1 0 0 1 1 1 0 0 3 1 0 1 3 1 1 1 1 1 0 0 4 1 — 0 2 1 2 1 2 2 1 1 1 1 1 4 1

0.05 0.00 0.05 — 0.00 0.00 0.20 0.00 0.15 0.00 0.10 0.05 0.05 0.05 0.05 0.00 0.00 0.05 0.05 0.05 0.00 0.00 0.15 0.05 0.00 0.05 0.15 0.05 0.05 0.05 0.05 0.05 0.00 0.00 0.20 0.05 — 0.00 0.10 0.05 0.10 0.05 0.10 0.10 0.05 0.05 0.05 0.05 0.05 0.20 0.05

Ontario (continued) Huntsville Ingersoll Iroquois Falls Jarvis Jellicoe Kapuskasing Kemptville Kenora Killaloe Kincardine Kingston Kinmount Kirkland Lake Kitchener Lakefield Landsdowne House Leamington Lindsay Lion’s Head Listowel London Lucan Maitland Markdale Martin Matheson Mattawa Midland Milton Milverton Minden Mississauga Mitchell Moosonee Morrisburg Mount Forest Muskoka Airport Nakina Napanee Newcastle New Liskeard Newmarket Niagara Falls North Bay Norwood Oakville Orangeville Orillia Oshawa Ottawa Owen Sound

(Continued) November 2006

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© Canadian Standards Association

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

190 310 400 245 260 255 295 260 290 350 375 295 260 275 345 365 370 360 395 465 310 340 315 300 205 220 260 365 300 350 320 300 375 330 205 295 335 235 380 275 230 365 350 280 335 355 350 330 255 290 230

240 365 480 325 315 325 360 315 360 415 435 360 315 330 415 415 435 415 480 535 380 410 380 360 240 255 310 415 360 415 365 355 455 380 240 360 385 285 460 330 280 415 435 345 410 435 415 410 310 390 280

275 405 545 395 350 385 410 350 415 465 490 410 350 375 470 455 495 465 550 595 435 470 430 410 260 285 350 455 410 465 400 390 525 425 260 410 425 320 525 375 325 460 505 400 475 500 465 475 355 465 325

310 450 610 460 390 450 460 390 470 520 540 460 390 420 530 500 540 510 620 650 500 530 490 460 290 310 390 500 450 520 430 430 600 470 290 460 460 360 590 420 360 500 580 460 540 570 520 540 400 550 370

0 0 0 1 2 1 1 2 1 0 1 0 2 0 0 0 0 0 0 1 1 0 2 0 0 0 2 0 2 0 0 0 0 0 0 2 0 0 0 0 1 0 0 1 0 0 0 0 1 1 1

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

0.00 0.05 0.00 0.05 0.10 0.05 0.05 0.10 0.05 0.00 0.05 0.05 0.10 0.05 0.00 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.10 0.05 0.00 0.00 0.10 0.05 0.10 0.00 0.00 0.00 0.00 0.05 0.00 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.05 0.05 0.05 0.05 0.00 0.05 0.05 0.05

0 1 0 1 4 1 3 4 1 2 1 1 4 — 0 1 1 — 1 1 1 0 3 1 0 0 4 — 4 0 0 0 0 1 0 3 1 1 1 1 1 1 0 1 0 0 — 0 1 1 2

0.00 0.05 0.00 0.05 0.20 0.05 0.15 0.20 0.05 0.10 0.05 0.05 0.20 — 0.00 0.05 0.05 — 0.05 0.05 0.05 0.00 0.15 0.05 0.00 0.00 0.20 — 0.20 0.00 0.00 0.00 0.00 0.05 0.00 0.15 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.05 0.00 0.00 — 0.00 0.05 0.05 0.10

Ontario (continued) Pagwa River Paris Parkhill Parry Sound Pembroke Penetanguishene Perth Petawawa Peterborough Petrolia Picton Plattsville Point Alexander Porcupine Port Burwell Port Colborne Port Credit Port Dover Port Elgin Port Hope Port Perry Port Stanley Prescott Princeton Raith Red Lake Renfrew Ridgeway Rockland Sarnia Sault Ste. Marie Schreiber Seaforth Simcoe Sioux Lookout Smiths Falls Smithville Smooth Rock Falls Southampton South Porcupine South River St. Catharines St. Marys Stirling Stratford Strathroy Streetsville St. Thomas Sturgeon Falls Sudbury Sundridge

(Continued)

80

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© Canadian Standards Association

Canadian Highway Bridge Design Code

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

340 275 330 405 300 310 255 390 350 240 335 285 295 355 355 320 275 340 300 330 345 430 210 330 360 350 305 350

410 330 410 485 355 380 310 460 415 285 385 360 360 415 435 380 330 410 355 380 415 510 245 410 420 435 380 415

475 375 475 545 390 435 355 520 465 320 425 415 410 465 500 430 370 470 390 425 470 575 275 475 470 505 435 465

530 420 550 610 430 500 400 580 520 360 460 480 460 520 570 480 420 530 430 470 530 640 300 550 520 570 500 520

0 1 1 0 0 0 0 0 1 0 0 1 2 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0

0.05 0.05 0.05 0.00 0.00 0.00 0.05 0.05 0.05 0.00 0.00 0.05 0.10 0.05 0.05 0.00 0.05 0.00 0.00 0.00 0.00 0.05 0.00 0.05 0.00 0.00 0.05 0.00

1 2 0 0 0 0 1 1 1 0 — 1 — 1 1 0 1 0 0 1 0 1 0 1 0 0 1 0

0.05 0.10 0.00 0.00 0.00 0.00 0.05 0.05 0.05 0.00 — 0.05 — 0.05 0.05 0.00 0.05 0.00 0.00 0.05 0.00 0.05 0.00 0.05 0.00 0.00 0.05 0.00

235 235 240 315 250 260 295 265 450 315 385 305 280 280 310 305 410 235 385 310 250

285 285 285 365 310 310 360 325 535 365 460 360 330 330 365 360 510 285 460 365 310

320 320 320 400 355 350 410 380 600 400 520 405 370 370 400 405 585 320 520 400 360

360 360 350 440 400 390 460 430 660 440 580 450 410 410 440 450 660 360 580 440 410

2 3 1 2 2 2 2 4 2 2 3 2 2 2 2 2 3 2 2 2 3

0.10 0.15 0.05 0.10 0.10 0.10 0.10 0.20 0.10 0.10 0.15 0.10 0.10 0.10 0.10 0.10 0.15 0.10 0.10 0.10 0.15

3 3 2 — — 2 4 5 4 4 4 3 3 3 4 4 — 4 — 4 4

0.15 0.15 0.10 — — 0.10 0.20 0.30 0.20 0.20 0.20 0.15 0.15 0.15 0.20 0.20 — 0.20 — 0.20 0.20

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Ontario (continued) Tavistock Temagami Thamesford Thedford Thunder Bay Tillsonburg Timmins Toronto Trenton Trout Creek Trout Lake Uxbridge Vanier Vittoria Walkerton Wallaceburg Waterloo Watford Wawa Welland West Lorne Whitby White River Wiarton Windsor Wingham Woodstock Wyoming Québec Acton Vale Alma Amos Anjou Arvida Asbestos Aylmer Bagotville Baie-Comeau Beaconsfield Beauport Bedford Belœil Brome Brossard Buckingham Cacouna Campbell’s Bay Camp Valcartier Chambly Chicoutimi

(Continued) November 2006

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© Canadian Standards Association

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

270 330 305 280 260 315 240 310 535 240 365 590 295 230 240 265 700 590 305 295 310 630 270 255 255 335 280 675 315 310 450 310 395 385 315 260 315 235 310 385 385 385 330 260 240 235 300 450 450 240 395 315

330 390 360 330 315 365 285 365 640 285 415 700 360 275 285 310 820 700 360 360 365 780 325 310 310 385 330 815 365 365 555 365 480 460 365 315 365 285 365 460 460 460 390 310 285 275 360 535 535 275 480 365

375 435 405 370 350 400 320 405 725 315 455 785 410 305 315 350 920 785 405 410 405 905 360 355 355 425 370 930 400 400 645 400 555 520 400 350 400 320 400 520 520 520 435 350 320 305 410 600 600 305 555 400

430 480 450 410 390 440 350 450 815 350 500 870 460 340 350 390 1020 870 450 460 450 1030 400 400 400 460 410 1030 440 440 730 440 630 580 440 390 440 360 440 580 580 580 480 390 350 340 450 660 660 330 630 440

1 2 2 2 2 2 2 2 1 2 1 1 2 2 2 2 1 1 2 2 2 0 2 3 3 1 2 0 2 2 2 2 6 3 2 2 2 1 2 3 3 3 2 1 1 2 2 2 2 2 4 2

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

0.05 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.05 0.10 0.05 0.05 0.10 0.10 0.10 0.10 0.05 0.05 0.10 0.10 0.10 0.00 0.10 0.15 0.15 0.05 0.10 0.05 0.10 0.10 0.10 0.10 0.40 0.15 0.10 0.10 0.10 0.05 0.10 0.15 0.15 0.15 0.10 0.05 0.05 0.10 0.10 0.10 0.10 0.10 0.20 0.10

2 3 3 4 3 4 3 3 — 4 1 1 4 — 4 3 1 1 4 4 4 0 3 4 4 — — — — 4 — — 6 4 — 3 4 2 4 — 4 4 3 2 2 4 4 3 3 4 5 4

0.10 0.15 0.15 0.20 0.15 0.20 0.15 0.15 — 0.20 0.05 0.05 0.20 — 0.20 0.15 0.05 0.05 0.20 0.20 0.20 0.00 0.15 0.20 0.20 — — — — 0.20 — — 0.40 0.20 — 0.15 0.20 0.10 0.20 — 0.20 0.20 0.15 0.10 0.10 0.20 0.20 0.15 0.15 0.20 0.30 0.20

Québec (continued) Coaticook Contrecœur Cowansville Deux-Montagnes Dolbeau Dorval Drummondville Farnham Fort-Chimo Fort-Coulonge Gagnon Gaspé Gatineau Gentilly Gracefield Granby Harrington Harbour Havre-Saint-Pierre Hemmingford Hull Iberville Inukjuak Joliette Jonquière Kenogami Knob Lake Knowlton Kovik Bay Lachine Lachute Lac-Mégantic Laflèche La Malbaie L’Ancienne Lorette LaSalle La Tuque Laval Lennoxville Léry Les Saules Lévis Loretteville Louiseville Magog Malartic Maniwaki Masson Matane Mont-Joli Mont-Laurier Montmagny Montréal

(Continued)

82

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Canadian Highway Bridge Design Code

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

315 315 285 260 315 640 315 310 260 315 295 250 520 635 310 385 235 450 410 260 300 315 260 315

365 365 330 310 365 760 365 365 310 365 360 310 615 745 365 460 280 535 505 315 360 365 310 365

400 400 365 350 400 850 400 400 350 400 410 355 690 830 400 520 320 600 585 350 410 400 350 400

440 440 400 390 440 940 440 440 390 440 450 395 760 950 440 580 360 660 660 390 460 440 390 440

2 2 1 1 2 1 2 2 2 2 2 3 1 0 3 3 2 2 5 2 1 2 1 2

0.10 0.10 0.05 0.05 0.10 0.05 0.10 0.10 0.10 0.10 0.10 0.15 0.05 0.00 0.15 0.15 0.10 0.10 0.30 0.10 0.05 0.10 0.05 0.10

4 — 0 2 4 1 4 4 3 — — — 4 — — 4 2 3 6 3 2 4 2 4

0.20 — 0.00 0.10 0.20 0.05 0.20 0.20 0.15 — — — 0.20 — — 0.20 0.10 0.15 0.40 0.15 0.10 0.20 0.10 0.20

335 240 260 270

380 285 310 310

425 315 350 345

460 350 390 380

0 1 2 2

0.00 0.05 0.10 0.10

0 2 4 4

0.00 0.10 0.20 0.20

310

365

400

440

2

0.10

4

0.20

280 385 220 310 410

330 460 255 365 505

370 520 285 400 585

310 660 310 440 660

2 3 2 2 4

0.10 0.15 0.10 0.10 0.20

— — 3 4 5

— — 0.15 0.20 0.30

270 310 285 255 315 315 365 305 400 240 280 305 330

310 365 330 295 365 365 435 360 495 285 335 360 390

345 405 365 325 400 400 495 405 570 315 370 405 435

380 450 400 360 440 440 550 450 640 350 410 450 480

2 2 2 2 2 2 3 2 5 1 2 2 2

0.10 0.10 0.10 0.10 0.10 0.10 0.15 0.10 0.30 0.05 0.10 0.10 0.10

3 3 4 4 4 4 4 3 6 3 3 4 3

0.15 0.15 0.20 0.20 0.20 0.20 0.20 0.15 0.40 0.15 0.15 0.20 0.15

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Québec (continued) Montréal-Nord Mont-Royal Nitchequon Noranda Outremont Percé Pierrefonds Pincourt Plessisville Pointe-Claire Pointe-Gatineau Port-Alfred Port-Cartier Poste-de-La-Baleine Préville Québec Richmond Rimouski Rivière-du-Loup Roberval Rock Island Rosemère Rouyn Salaberry-deValleyfield Schefferville Senneterre Shawville Ste-Agathe-desMonts Ste-Anne-deBellevue St-Canut Ste-Foy St-Félicien St-Hubert St-Hubert-deTémiscouata St-Hyacinthe St-Jean St-Jérôme St-Jovite St-Lambert St-Laurent St-Nicolas Sutton Tadoussac Témiscaming Thetford Mines Thurso Trois-Rivières

(Continued) November 2006

83

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© Canadian Standards Association

Table A3.1.1 (Continued)

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

240 310 300 330 315 260 300 260 315 235

285 365 360 390 365 310 360 310 365 285

315 405 405 435 400 350 410 350 400 320

350 450 450 480 440 390 450 390 440 360

1 2 2 2 2 2 1 2 2 2

0.05 0.10 0.10 0.10 0.10 0.10 0.05 0.10 0.10 0.10

3 — 3 3 4 3 2 3 — 2

0.15 — 0.15 0.15 0.20 0.15 0.10 0.15 — 0.10

380 335 375 290 300 295 360 285 460 355 410 385 450 515 275

480 410 455 360 380 360 455 360 560 435 510 460 535 615 330

565 475 525 415 440 410 535 415 640 500 585 520 600 690 370

650 540 600 470 510 460 620 480 720 570 660 590 670 770 420

1 1 1 1 3 1 1 2 1 1 1 1 1 1 1

0.05 0.05 0.05 0.05 0.15 0.05 0.05 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.05

2 1 2 2 3 2 2 3 2 2 1 2 2 1 2

0.10 0.05 0.10 0.10 0.15 0.10 0.10 0.15 0.10 0.10 0.05 0.10 0.10 0.05 0.10

410 410 405 485 400 390 395 365 400 355 435 445 515 425 400 465 400 590 385 390 465

510 485 505 565 505 480 480 455 505 455 530 535 590 530 480 535 480 675 480 480 535

585 545 585 625 590 555 550 535 590 535 610 605 650 615 545 595 545 740 555 555 595

660 600 670 680 670 630 620 610 670 620 690 680 710 700 620 650 620 800 640 630 650

1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2

0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10

1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 2 1 1 1 1 2

0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.05 0.05 0.10 0.05 0.05 0.05 0.05 0.10

Hourly mean wind pressure, Pa, for return periods of Location

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Québec (continued) Val-d’Or Valleyfield Varennes Verchères Verdun Victoriaville Ville-Marie Waterloo Westmount Windsor Mills New Brunswick Alma Bathurst Campbellton Chatham Edmundston Fredericton Gagetown Grand Falls Moncton Oromocto Sackville Saint John St. Stephen Shippegan Woodstock Nova Scotia Amherst Antigonish Bridgewater Canso Dartmouth Debert Digby Greenwood Halifax Kentville Liverpool Lockeport Louisbourg Lunenburg New Glasgow North Sydney Pictou Port Hawkesbury Springhill Stewiacke Sydney

(Continued)

84

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© Canadian Standards Association

Canadian Highway Bridge Design Code

Table A3.1.1 (Continued)

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

480 455 455 495

550 530 535 560

620 600 620 630

1 1 1 1

0.05 0.05 0.05 0.05

1 1 1 1

0.05 0.05 0.05 0.05

Hourly mean wind pressure, Pa, for return periods of Location

10 yr

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Nova Scotia (continued) Tatamagouche Truro Wolfville Yarmouth

395 370 355 410

Prince Edward Island Charlottetown Souris Summerside Tignish

460 415 520 610

530 485 615 700

590 540 690 775

660 600 760 850

1 1 1 1

0.05 0.05 0.05 0.05

1 1 1 1

0.05 0.05 0.05 0.05

570 515 460 460 785 575 460 285 590 460 315 545 570 620 605 315 560 315

670 615 535 535 935 670 535 330 675 535 365 620 735 700 710 365 670 365

750 690 595 595 1050 745 595 365 740 595 400 675 870 770 800 400 755 400

830 770 660 660 1170 820 660 400 810 660 440 730 1010 840 890 440 840 440

1 1 1 0 1 1 1 0 2 1 1 1 1 1 1 0 1 1

0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.05 0.05

1 1 1 1 1 1 1 — 2 1 1 1 0 1 1 0 1 1

0.05 0.05 0.05 0.05 0.05 0.05 0.05 — 0.10 0.05 0.05 0.05 0.00 0.05 0.05 0.00 0.05 0.05

285 230 450 230 190 260 280

340 275 535 275 245 315 330

380 310 600 310 295 350 370

420 340 660 340 340 390 420

5 4 6 5 4 2 4

0.30 0.20 0.40 0.30 0.20 0.10 0.20

3 2 4 3 1 1 2

0.15 0.10 0.20 0.15 0.05 0.05 0.10

720 520 700 390 440 460 460 390 950 760

2 0 1 1 1 1 1 1 1 2

0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.10

1 1 1 0 0 0 0 0 0 1

0.05 0.05 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.05

Newfoundland and Labrador Argentia Bonavista Buchans Cape Harrison Cape Race Corner Brook Gander Goose Bay Grand Bank Grand Falls Labrador City Port aux Basques St. Anthony Stephenville St. John’s Twin Falls Wabana Wabush Lake Yukon Territory Aishihik Dawson Destruction Bay Snag Teslin Watson Lake Whitehorse

Northwest Territories Aklavik Coppermine Fort Good Hope Fort Providence Fort Resolution Fort Simpson Fort Smith Hay River Holman Island Inuvik

370 330 480 265 290 300 300 265 635 390

500 400 565 310 350 360 360 310 755 525

610 460 635 350 395 410 410 350 855 640

(Continued)

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Table A3.1.1 (Concluded) Hourly mean wind pressure, Pa, for return periods of Location

10 yr

25 yr

50 yr

100 yr

Velocityrelated seismic zone, Zv

Zonal velocity ratio, V

Accelerationrelated seismic zone, Za

Zonal acceleration ratio, A

Northwest Territories (continued) Mould Bay Norman Wells Port Radium Rae Tungsten Yellowknife

475 410 380 345 285 345

580 550 460 415 365 415

670 665 525 470 445 470

760 790 590 530 520 530

1 1 1 1 2 1

0.05 0.05 0.05 0.05 0.10 0.05

1 0 0 0 1 0

0.05 0.00 0.00 0.00 0.05 0.00

535 395 420 410 440 615 750 490 475 565 680 460 460 520 845

665 480 485 490 510 765 885 570 580 670 800 560 535 610 1065

770 550 540 545 565 890 995 640 670 750 900 640 595 690 1235

870 620 590 600 620 1020 1100 710 760 840 1000 720 660 770 1410

0 1 0 0 0 3 0 0 0 0 1 0 0 1 0

0.00 0.05 0.00 0.00 0.00 0.15 0.05 0.00 0.05 0.05 0.05 0.05 0.00 0.05 0.05

0 1 0 0 0 5 1 0 1 1 4 1 0 2 2

0.00 0.05 0.00 0.00 0.00 0.30 0.05 0.00 0.05 0.05 0.20 0.05 0.00 0.10 0.10

Nunavut Alert Arctic Bay Baker Lake Cambridge Bay Chesterfield Inlet Clyde River Coral Harbour Eskimo Point Eureka Iqaluit Isachsen Nottingham Island Rankin Inlet Resolute Resolution Island

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

160

140

120

100 90 80

60

40

20

14

C •A •N •A •D •A 100 50 0

12

14

12

24 24 • 22 • Snag

800 KM

60

Iqaluit •

Baker Lake

• Terrace

20

20 242628 30

•

22 Churchill

EDMONTON

• Port Harrison

•

• Cold Lake

Armstrong

• Kenora

100

95

90

•

26

24 26

50

28 26 24

28 30• Goose Bay

26

• Nitchequon

26

ST. JOHN‘S •

22 • Stephenville 45

26 24

Moosonee •

34 32 30

40

105

•

• Trout Lake

• Lethbridge Yorkton • REGINA • Dauphin • 28 28 28 30 32 WINNIPEG • 32 30 30 32

110

Chimo

Hopedale

River

Winisk •

Prince • The Pas • Albert • Saskatoon

• Calgary

• Fort

• Great Whale

Cranberry • Portage

• Kamloops • Vancouver

• VICTORIA Kimberley

55

Uranium • City

• Beaverlodge • Quesnel Williams • Lake

16 18

Chesterfield •

Fort • Vermilion • Ft. St. John

•



640

14

Fort

115

480

• Port Radium

• Nelson

120

320

• Arctic Bay

• Holman

• YELLOWKNIFE

45

160

Dawson

55

22

500

• Inuvik

• WHITEHORSE

50

400

Maximum mean daily temperature, °C.

20 18 16

Coppermine •

22 24

300

KM

14

60

200

MILES

160 80 0

22

100

MILES

• Pagawa 30 32

Chatham •

• Sydney

30 • FREDERICTON Val d’Or • QUEBEC • 28 • HALIFAX 28 Sudbury • 26 Montreal • Yarmouth 24 • S. S. Marie • 24 OTTAWA • 30 30 30 32 • TORONTO 30 28 30 30 • Windsor 30 32 32

85

80

75

70

65

40

60

Figure A3.1.1 Maximum mean daily temperature (See Clause 3.9.4.1.)

October 2011 (Replaces p. 87, November 2006)

87

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© Canadian Standards Association

160

140

120

100 90 80

60

40

20

-52 -50 -48

C •A •N •A •D •A 100 50 0

100

200 300 400

160

320 480 640

MILES 160 80 0

MILES

KM

-50

-50 -48 -50

500

800 KM

Minimum mean daily temperature, °C.

-46

• Inuvik 60

• Arctic Bay-44 -42

• Holman

• Dawson -48 -46 • Snag

60

Coppermine •

-44

• Port Radium

• WHITEHORSE -42 -40

55

• YELLOWKNIFE

-38 -34 • Terrace -20 -18 -16

Iqaluit •

Baker Lake

Fort

55

Chesterfield •

• Nelson Fort • Vermilion • Ft. St. John

-40

Uranium • City

• Fort

-38 -36 -34 •-32

Hopedale

30 • Beaverlodge Chimo Churchill • • Quesnel -28 Williams • Lake • Goose Bay EDMONTON • Cold Lake Great Whale • -28 -24 • River Cranberry • Portage Winisk • • Kamloops -22 Nitchequon • Prince • The Pas • • Vancouver ST. JOHN‘S • Albert • VICTORIA • Trout Lake • Calgary Saskatoon Stephenville -10-14 -16 • • -20-22Kimberley • -18 • Lethbridge -28 Yorkton • Moosonee • -32 REGINA • Dauphin • -36-38 Armstrong • Sydney -38 • Pagawa • Chatham • WINNIPEG • • Kenora • FREDERICTON -36 • White RiverVal d’Or • QUEBEC • • HALIFAX -34 -28 Sudbury • -30 -20 Yarmouth Montreal • • • S. S. Marie -32 OTTAWA • -28 30 -30 -32 • TORONTO -26 -28 -24 -22 • Windsor

50

• Port Harrison

-14 -12 -10

45

40

120



115

110

105

100

95

90

85

80

75

70

65

50

45

40

60

Figure A3.1.2 Minimum mean daily temperature (See Clause 3.9.4.1.)

88

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© Canadian Standards Association

Canadian Highway Bridge Design Code

160

140

120

100 90 80

60

40

20

C •A •N •A •D •A

100 50 0

100

200 300 400 500

160

320 480 640 800

MILES

MILES

160 80 0 KM

KM

Annual mean relative humidity, %

70 • Inuvik 60

70

• Arctic Bay

• Holman

• Dawson

60

80

60

• Snag

Coppermine •

80

• Port Radium

• WHITEHORSE

80 Iqaluit •

55 Baker Lake

• YELLOWKNIFE

60

Fort

Chesterfield •

• Nelson Fort

Prince• Terrace • Rupert

• Vermilion • Ft. St. John

Uranium

• City

• Beaverlodge

50

• Quesnel Williams • Lake

50

•

• Vancouver

Kimberley

45

•

• Calgary

80 Cranberry

• Portage Prince • The Pas • Albert • Saskatoon

• Great Whale River

• Nitchequon

45 Armstrong

WINNIPEG •

• Kenora

90

•

• Pagawa

Chatham •

• White RiverVal d’Or •

60

Sudbury • • S. S. Marie

QUEBEC •

Montreal • OTTAWA •

60

70 110

105

ST. JOHN‘S • • Stephenville

Moosonee •

•

• TORONTO70

115

50

• Trout Lake

40

120

80

•

• Goose Bay

Winisk •

• Lethbridge50

80 70

Hopedale

Chimo

• Cold Lake

Yorkton • REGINA • Dauphin

80

• Port Harrison • Fort

Churchill •

EDMONTON

• Kamloops

• VICTORIA

55

100

95

70 90

85

70

• Sydney

• FREDERICTON • HALIFAX • Yarmouth

40

80 80

• Windsor 80

75

70

65

60

Figure A3.1.3 Annual mean relative humidity (See Clauses 8.4.1.5.2, 8.4.1.6.3, and 8.7.4.3.2.)

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160

140

120

100 90 80

60

40

20

C •A •N •A •D •A 100 50 0

100

200 300 400 500

160

320 480 640 800

MILES

MILES

160 80 0 KM

• Inuvik 60

• Arctic Bay

• Holman

• Dawson

KM

Ice thickness 4 mm 12 mm 31 mm 66 mm

Zone Light Moderate Heavy Extreme

60

• Snag Coppermine •

• Port Radium

• WHITEHORSE

Iqaluit •

55 Baker Lake

• YELLOWKNIFE Fort • Nelson Prince • Terrace

• Rupert

Chesterfield •

Fort • Vermilion • Ft. St. John

Uranium • City

• Beaverlodge

50

• Quesnel Williams • Lake

EDMONTON

•

• Port Harrison • Fort

Churchill •

Hopedale

•

Chimo

50

• Goose Bay

• Cold Lake

• Great Whale

Cranberry • Portage

• Kamloops Prince • The Pas • • Vancouver Albert • VICTORIA • Calgary • Saskatoon Kimberley • • Lethbridge Yorkton • REGINA • Dauphin •

45

55

River

Winisk •

• Nitchequon

ST. JOHN‘S • • Stephenville

• Trout Lake

45 Moosonee • Armstrong

WINNIPEG •

• Kenora

•

• Pagawa

Chatham •

• White RiverVal d’Or • Sudbury • • S. S. Marie

40

QUEBEC •

• Sydney

• FREDERICTON • HALIFAX

Montreal • OTTAWA •

• Yarmouth

40

• TORONTO • Windsor 120

115

110

105

100

95

90

85

80

75

70

65

60

Figure A3.1.4 Ice accretion (See Clause 3.12.6.2.)

90

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

160

140

120

100 90 80

60

40

20

C •A •N •A •D •A 100 50 0

100

200 300 400 500

160

320 480 640 800

MILES

MILES

160 80 0 KM

KM

Permafrost region 1 — Discontinuous zone 2 — Continuous zone • Inuvik 60

• Arctic Bay

• Holman

• Dawson

60

• Snag Coppermine •

• Port Radium

• WHITEHORSE

2 Iqaluit •

55 Baker Lake

• YELLOWKNIFE Fort • Nelson Prince • Terrace

• Rupert

Chesterfield •

Fort • Vermilion • Ft. St. John

• Beaverlodge

50

• Quesnel Williams • Lake

EDMONTON

•

Uranium • City

1

• Port Harrison • Fort

Churchill •

Hopedale

•

Chimo

1

50

• Goose Bay

• Cold Lake

• Great Whale

Cranberry • Portage

• Kamloops Prince • Vancouver The Pas • Albert • • VICTORIA • Calgary • Saskatoon Kimberley • • Lethbridge Yorkton • REGINA • Dauphin •

45

55

River

Winisk •

• Nitchequon

ST. JOHN‘S • • Stephenville

• Trout Lake

45 Moosonee • Armstrong

WINNIPEG •

• Kenora

•

• Pagawa

Chatham •

• White RiverVal d’Or • Sudbury • • S. S. Marie

40

QUEBEC •

• Sydney

• FREDERICTON • HALIFAX

Montreal • OTTAWA •

• Yarmouth

40

• TORONTO • Windsor 120

115

110

105

100

95

90

85

80

75

70

65

60

Figure A3.1.5 Permafrost region (See Clause 6.1.)

November 2006

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160

140

120

100 90 80

60

40

20

C •A •N •A •D •A 100 50 0

• Inuvik Dawson

• Arctic Bay

• Holman

320 480 640 800 KM

g

0 .04 .08 .11 .16 .23 .32

A

0 .05 .10 .15 .20 .30 .40

Za

0

1

2

3

4

5

6

.32

60

.23

.0 8

.11 .08

160

KM

.16

.32 .16 •.16 .32 • Snag

200 300 400 500 MILES

160 80 0

.04

60

100

MILES

.08

.04

.32 .16

.11

Coppermine •

• Port Radium

• WHITEHORSE

.04

.04 Fort

Uranium • City

.1 1

.08

.32

• Quesnel Williams • Lake

EDMONTON

•

• Kamloops • Vancouver .08 45 .23

Kimberley

•

• Calgary

.04 • Port Harrison • Fort

Churchill •

• 50

• Goose Bay

• Cold Lake

• Great Whale

Cranberry • Portage

Yorkton • REGINA • Dauphin

River

Winisk •

Prince • The Pas • Albert • Saskatoon

.16 .32

Moosonee •

•

Armstrong

WINNIPEG •

• Kenora

•

.0

Stephenville • 45

8 Sydney •

• Pagawa

.11

• White River Sudbury • • S. S. Marie

40

.16 .32

• Nitchequon .16

.04

• Trout Lake

• Lethbridge

.32

Hopedale

Chimo

• ST. JOHN’S

Fort • Vermilion • Ft. St. John

• Beaverlodge

50

55

Chesterfield •

• Nelson • Terrace

.08

Iqaluit •

Baker Lake

• YELLOWKNIFE

QU

.1

EB

6

EC

Montreal • OTTAWA •

•

.11

• FREDERICTON • HALIFAX

.08

.16 55 .32

.08

• Yarmouth

40

.04

.08 • TORONTO • Windsor 120

115

110

105

100

95

90

85

80

75

70

65

60

Figure A3.1.6 Contours of peak horizontal ground accelerations (in units of g) having a probability of exceedance of 10% in 50 years (See Clauses 3.13 and 4.4.3.)

92

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

160

140

120

100 90 80

60

40

20

C •A •N •A •D •A

.04

100 50 0

100

200 300 400 500

160

320 480 640 800

MILES

MILES

160 80 0 KM

.08

.16 .32 • • Snag

.08

.16

• Inuvik

.16

60

.08 .16

• Arctic Bay

• Holman

KM

m/s

0 .04 .08 .11 .16 .23 .32

v

0 .05 .10 .15 .20 .30 .40

Zv

0

1

2

3

4

5

6

.08

Dawson

60

Coppermine •

• Port Radium

• WHITEHORSE

Iqaluit •

55 Baker Lake

• YELLOWKNIFE

.32 Fort • Nelson Prince • Rupert

• Terrace

Chesterfield • Fort

• Vermilion • Ft. St. John

Uranium • City

• Beaverlodge

50

• Quesnel Williams • Lake

.32

EDMONTON

•

• Kamloops

.16 45

• Vancouver

• VICTORIA .16 Kimberley • .08 .04

55

• Calgary

• Port Harrison • Fort

Churchill •

Hopedale

Chimo

• 50

• Goose Bay

• Cold Lake

• Great Whale

Cranberry

• Portage

• Nitchequon

ST. JOHN‘S • • Stephenville

• Trout Lake

• Lethbridge

Yorkton • REGINA • Dauphin

River

Winisk •

Prince • The Pas • Albert • Saskatoon

Armstrong

WINNIPEG •

• Kenora

•

• Pagawa

40

Chatham •

.32

• White RiverVal d’Or • Sudbury • • S. S. Marie

45

.32

Moosonee •

•

QUEBEC •

.16

.08 • FREDERICTON • HALIFAX

Montreal • OTTAWA •

.08 .04 • TORONTO

• Sydney .08 .16

• Yarmouth

40

.04

• Windsor 120

115

110

105

100

95

90

85

80

75

70

65

60

Figure A3.1.7 Contours of peak horizontal ground velocities (in units of m/s) having a probability of exceedance of 10% in 50 years (See Clause 3.13.)

November 2006

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Annex A3.2 (normative) Wind loads on highway accessory supports and slender structural elements Note: This Annex is a mandatory part of this Code.

A3.2.1 General Highway accessory supports and slender structural elements shall be designed for horizontal drag loads at the serviceability and ultimate limit states and, where appropriate, shall be designed for across-wind loads induced by vortex shedding excitation at the FLS. The loading combinations to be considered and the load factors to be used shall be as specified in Table A3.2.1. For each loading combination, every load that is to be included shall be multiplied by the load factor specified and the resulting load effects shall be calculated. The factored load effects shall then be added together to obtain the total factored load effect.

94

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Table A3.2.1 Load combinations and load factors for highway accessory supports and slender structural elements (See Clauses A3.2.1, 12.5.5.3, and 12.5.5.4.1.)

Permanent loads Loads

Exceptional loads

Transitory loads

D

E

P

K

W

S

EQ

A

0

0

0

0

1.00

0

0

0

1.00

1.00

1.00

0.80

0.70

1.00

0

0

αD αD αD

αE αE αE

αP αP αP

1.25 0 0

1.30 0.70 0.70

0 0 0

0 1.00 0

0 0 1.30

Fatigue limit state FLS Combination A1 Serviceability limit state SLS Combination A1 Ultimate limit states ULS Combination A1 ULS Combination A2 ULS Combination A3

Note: For ultimate limit states, the maximum or minimum value of α D , α E , and α P as specified in Clause 3.5.2 shall be used. Legend: A = ice accretion load D = dead load E = loads due to earth pressure and hydrostatic pressure, including surcharges but excluding dead load EQ = earthquake load K = all strains, deformations, and displacements and their effects, including the effects of their restraint and the effects of friction or stiffness in bearings. Strains and deformations include strains and deformations due to temperature change and temperature differential, concrete shrinkage, differential shrinkage, and creep, but not elastic strains P = secondary prestress effects S = load due to differential settlement and/or movement of the foundation W = wind load on structure

A3.2.2 Horizontal drag load The wind-induced horizontal drag load acting on the exposed frontal area of slender structural members shall be as specified in Clause 3.10.2.2, but using the values of Ch specified in Table A3.2.2.

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Table A3.2.2 Horizontal drag coefficient, Ch (See Clause A3.2.2.) Type and shape of members

Horizontal drag coefficient, Ch

Two members or trusses, one in front of the other Cylindrical Flat

1.9 2.9

Three trusses forming a triangular cross-section Cylindrical Flat

1.7 2.6

Traffic signals

1.2

Luminaires with rounded surfaces 0.5 Luminaires with rectangular flat surfaces

1.2

Sign panels and noise barriers Ratio of sides = 1 1 < ratio of sides ≤ 10 Ratio of sides > 10

1.1 1.2 1.3

Single member or truss

With D(qCe )0.5 ≤ 3.6 With 3.6 < D (qCe )0.5 < 7.2

Cylindrical

Dodecagonal*

6.42

1.2

D

1.3

0.5

0.65 (qC e )

2.60

1.2

0.8

D 0.6 (qC e )0.3

Octagonal†

1.2

1.2

Hexdecagonal 0 ≤ r < 0.26

1.1

1.37 + 1.08r −

r ≥ 0.26

1.1

0.55 +

1.2

1.7

Elliptical Broad side facing wind

1.7(D1/D2 – 1) + CD1(2 – D1/D2)

C D2

D (qC e )0.5 13.3

[7.2 − D (qC e )

Flat‡

Narrow side facing wind

With D(qCe )0.5 ≥ 7.2

1.7

0.5

]

−

Dr (qC e )0.5 0.83 – 1.08r 3.3 0.55

6.5 1.7

( 4 − D1 / D2 ) 3

*Valid for member with a ratio of corner radius to distance between parallel faces equal to or greater than 0.125. †The corners are assumed to be slightly rounded for octagonal sections. With sharp corners, a coefficient of 1.4 shall be used. ‡Flat members are shapes that are essentially flat in elevation, including plates, angles, and squares with slightly rounded corners and panels with variable message signs. A coefficient of 2.0 shall be used for single flat members, including plates, angles, and squares, with sharp corners. Legend: CD1 = drag coefficient of cylindrical shape with a diameter of D1 CD2 = drag coefficient of cylindrical shape with a diameter of D2 D = width or diameter of member, m D1/D2 = ratio of major to minor diameter of ellipse (maximum value of 2) r = ratio of corner radius to radius of inscribed circle

96

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Canadian Highway Bridge Design Code

A3.2.3 Horizontal drag load on highway accessory supports The horizontal drag load on members of highway accessory supports shall be in accordance with Clause A3.2.2. When the effects of wind loads are to be combined with those of ice accretion loads, the increase in exposed frontal area caused by ice accretion shall be considered. For highway accessories that are less than 1 m2 in area, the exposed frontal area for all wind directions shall be taken as constant and equal to the maximum exposed frontal area in any direction. The action of wind loads on highway accessory supports shall be as shown in Figure A3.2.1 and in accordance with the following: (a) Horizontal support members shall be designed for wind loads Wa and Wh applied normal to the accessories and horizontal support members, respectively, and acting at the centroids of their respective areas. (b) Vertical support members shall be designed for wind loads imposed from any direction by applying normal and transverse wind loads simultaneously to the member in the combinations specified in Table A3.2.3. The basic load (BL) specified in Table A3.2.3 shall be the wind loads Wa , Wh , and Wv applied normal to the accessories and support members, respectively, and acting at the centroids of their respective areas. The transverse wind load may be assumed to be equally distributed to all vertical support members. (c) The maximum torque on single vertical support members supporting two or more horizontal support members shall be calculated by assuming that the wind load acts on a horizontal support member only if the wind load acting on that member increases the torque. The resulting torsional effects shall be combined with other effects due to full wind load. The maximum torque on single vertical support members supporting highway accessories shall be not less than the full wind load multiplied by 0.15 times the overall width of the highway accessory.

Table A3.2.3 Normal and transverse load combinations (See Clause A3.2.3.)

November 2006

Normal component

Transverse component, t c

1.0BL 0.6BL

0.2BL 0.3BL

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b e2 wa , wh

wv

tc (wa , wh , wv)

e1

b

e wa Torque on support: T = (wa + wh)e e = 0.15b

High mast — Pole type

wa

wv

wh

Torque on support: T = wae e = 0.15b

Post-top luminaire

wa

wh

wv

Torque on support: T = (whe1) + (wae2) (for torque, apply wind on one side of support only)

Common light standard (balanced or unbalanced)

e tc (wa , wh , wv) wh wv

wa(1)

wa(2)

wh wa wv

tc (wa , wh , wv) wv

wa

wh

wa

Cantilever if required

wv

Sign bridge

Butterfly e1

b

e2 tc(wa , wh , wv) wa

wa

wv

wh wa

wa wa

wh wv wh wa

Torque on support: T = wae1 + whe2

Cantilever

e = 0.15 b

Two or more supports

wv

Torque on support: T = wae

Loads on sign support structure

Figure A3.2.1 Loads on sign, luminaire, and traffic signal support structures (See Clause A3.2.3.) (Continued)

98

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

e3 e2 e1

tc (wa , wh , wv)

wh w a

wv

e3 e2 e1

tc(wa , wh , wv)

wa

wh

wa wa

Torque on support:

wa

wa

Torque on support: T = (whe1) + (wae2) + (wae3) (for torque, apply wind on one side of support only)

T = (whe1) + (wae2) + (wae3)

Combination cantilever arm luminaires and traffic signals b

wh

wv

Cantilever arm mounted traffic signals (balanced or unbalanced)

tc (wa , wh , wv) wv

wa wh

wh

wa

wh

wa

wh

wa

wh

wa

wh

wv

wh , wa wa Torque on support: T = wae e = 0.15b

wv

Pole-top-mounted traffic signal

Bridge-mounted traffic signs

Note: Resultant wind forces are applied at the centroid of each component.

Figure A3.2.1 (Concluded)

A3.2.4 Across-wind loads A3.2.4.1 General The dynamic effects of across-wind loads induced by vortex shedding excitation on slender structural members shall be considered at the FLS. The stress range shall be taken as twice the maximum stress calculated in accordance with Clause A3.2.4.3.2. The stress range limit shall be taken as that corresponding to a fatigue life of over 2 000 000 cycles for the appropriate material and detail unless a detailed fatigue damage analysis shows that a different limit is appropriate.

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A3.2.4.2 Vortex shedding excitation The significance of vortex shedding excitation for a slender structural member shall be examined in accordance with Clause A3.2.4.3 as follows: (a) For members with a constant diameter or frontal width: ni < ne = SV/D where ni

= natural frequency of member for mode of vibration, i, Hz

ne

= frequency at which vortex shedding occurs for a member with a constant diameter or frontal width, Hz

S

= Strouhal number for the cross-sectional geometry, as specified in Table A3.2.4

V

= hourly mean wind speed at the location of the member being considered, m/sec =

1.24 qC e

where q

= hourly mean reference wind pressure for the design return period, Pa

Ce = wind exposure coefficient specified in Clause 3.10.1.4 D

= constant diameter or frontal width of member, m

The height above ground used to calculate Ce shall correspond to the height above ground of the location of coordinate x. The location at which ne is calculated shall be taken as the top of the member. (b) For members with a tapered diameter or frontal width: ni < ne (x) = SV/D(x) where ni

= natural frequency of member for mode of vibration, i, Hz

ne (x) = frequency at which vortex shedding excitation occurs at location x for a member with a tapered diameter or frontal width, Hz S

= Strouhal number for the cross-sectional geometry, as specified in Table A3.2.4

V

= hourly mean wind speed at the location of the member being considered, m/sec =

1.24 qC e

where q

= hourly mean reference wind pressure for the design return period, Pa

Ce = wind exposure coefficient specified in Clause 3.10.1.4 D(x) = diameter or frontal width of a tapered member at location x, m where x

= coordinate describing location along the member

ne (x) shall be calculated at sufficient locations along the member to determine at which locations vortex shedding excitation can occur.

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Table A3.2.4 Vortex shedding data (See Clause A3.2.4.2.)

Circular cross-section Subcritical Re < 3 × 105 Supercritical and transcritical Re ≥ 3 × 105 Square cross-section Multi-sided members and rolled structural shapes

S

˜ C L

B

L

0.18 0.25 0.11 0.15

0.50 0.20 0.60 0.60

0.10 0.30 0.25 0.25

2.5 1.0 3.0 2.75

Note: The Reynolds number, Re , shall be calculated as (VD/1.5) × 105. Legend: B = band width, i.e., a measure of the variability of the vortex shedding frequency ˜ C = root-mean-square (RMS) lift coefficient for the cross-sectional geometry L L = correlation length, i.e., the length (as a ratio of the diameter) over which the vortices act in phase S = Strouhal number

A3.2.4.3 Structural response to vortex shedding excitation A3.2.4.3.1 Displacements The magnitude of the peak member displacement, yi (x), due to vortex shedding excitation at any location, x, along the member for mode of vibration, i, shall be taken as follows: (a) For a member with a constant diameter or frontal width: yi (x) = ai μi (x) where yi (x) = peak member displacement due to vortex shedding excitation at location x for mode of vibration, i, m ai

= modal coefficient of magnitude of the oscillatory displacement for mode of vibration, i, for a member with a constant diameter or frontal width, m =

3.5CL rD 4 π0.25C

Bz i ( 4πS )2 GMi

f yi (x) ≤ 0.025D

i

H

2 ( r )CL D3 ∫ mi ( x ) dx

=

0

( 4πS )2 z i GMi

f yi (x) > 0.025D

i

where H

C =

x 3a mi2 ( x ) (H / D )2 dx ∫ 1+ H / 2LD 0 H 1 + 3a

where

α

= wind velocity profile exponent, taken as 0.36 for city centres and industrial areas, 0.25 for suburban and well-wooded areas, and 0.15 for open country with scattered trees

ζi

= structural damping for the i th mode, expressed as a ratio of critical damping

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GMi = generalized mass for mode of vibration, i, kg H

=

∫ m ( x )mi ( x ) dx 2

0

where m(x) = mass per unit length of member at location x, kg/m H

= length of member, m

μ i (x) = amplitude of the member mode shape at location x for mode of vibration, i = air mass density, taken as 1.29 kg/m3 (b) For a member with a tapered diameter or frontal width: yi (x) = ai (x1)μi (x) where ai (x 1) = modal coefficient of magnitude of the oscillatory displacement due to vortex shedding excitation at location x 1 for mode of vibration, i , for a member with a tapered diameter or frontal width 2πL CL rD 4 ( x1) = 3.5 mi ( x 1 ) z i y ( x1) ( 4πS )2 GMi ˜

=

2 r C L D 2 ( x1 ) ∫

x1 + b

D( x ) mi ( x ) dx

x1 − b ( 4πS )2 z i GMi

if yi (x) > 0.025D(x) at any location x

where x1

= location along a tapered member at which vortex shedding excitation is being considered

ψ (x 1) = b

dD( x1) a D( x1) + dx x

= length of the member above or below location x 1 for which D(x) is within a certain percentage of D(x 1) (the percentage shall be taken as 10% unless a smaller value can be justified)

For a tapered member, ai (x 1) shall be calculated for all locations, x 1, along the member at which vortex shedding excitation can occur for mode of vibration, i, as determined in accordance with Clause A3.2.4.2. The largest value of ai (x 1) calculated shall be used for determining yi (x) and the peak inertia loads specified in Clause A3.2.4.3.2.

A3.2.4.3.2 Stresses The maximum stresses in a member due to vortex shedding excitation shall be calculated by loading the member with the peak inertia loads acting statically. The magnitude of the peak inertia load per unit length at any location x along the member for mode of vibration, i, shall be taken as F i (x) = (2πni )2yi (x)m(x) where F i (x) = peak inertia load at location x for mode of vibration, i, N/m The calculation of the peak inertia loads shall take into account the mass of all components attached to the member.

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A3.2.4.3.3 Damping ratios

Unless experimentally determined values are available, the value of ζ i for members in all modes of vibration shall be taken as 0.0075 for steel and aluminum members and 0.015 for concrete members.

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Annex A3.3 (normative) Vessel collision Notes: (1) This Annex is a mandatory part of this Code. (2) Taken together, this Annex and Clause 3.14 constitute a condensed version of AASHTO GVCB-1 (but written, unlike AASHTO GVCB-1, in SI units). AASHTO GVCB-1 may be used as an alternative to Clause 3.14 and this Annex for detailed design for vessel collision. It may also be used as a reference when fuller information than is provided by Clause 3.14 and this Annex is needed.

A3.3.1 Vessel frequency A vessel frequency distribution shall be determined for the bridge site. The number of vessels, N, passing under the bridge, based on size, type, loading condition, and navigable water depth, shall be developed for each pier and span element to be evaluated. The vessel frequency distribution for vessels should be developed and modelled using dead weight tonnage (DWT) classification intervals appropriate for the waterway vessel traffic. See Annex CA3.3 of CSA S6.1.

A3.3.2 Design vessel selection A3.3.2.1 General Design vessel selection shall be based on Method I or Method II (Clauses A3.3.2.2 and A3.3.2.3, respectively). Once the design vessel is identified, the ship collision force can be evaluated using Clause A3.3.5.

A3.3.2.2 Method I Note: See Clause 3.14.2 for bridge classifications.

The following requirements shall apply: (a) Class I bridges: the design vessel size shall be such that the annual number of passages of vessels larger than the design vessel amounts to a maximum of 5% of the total annual number of merchant vessels that could impact the bridge element, but not more than 50. (b) Class II bridges: the design vessel size shall be such that the annual number of passages of vessels larger than the design vessel amounts to a maximum of 10% of the total annual number of merchant vessels that could impact the bridge element, but not more than 200.

A3.3.2.3 Method II Note: See Clause 3.14.2 for bridge classifications.

The following requirements shall apply: (a) Class I bridges: the maximum annual frequency of collapse, AFmax , for the whole bridge shall be 0.0001, i.e., a probability of 1 in 10 000. (b) Class II bridges: the maximum annual frequency of collapse, AFmax , for the whole bridge shall be 0.001, i.e., a probability of 1 in 1000. The maximum annual frequency of bridge collapse for the total bridge, AFmax , as determined in accordance with Item (a) or (b), shall be distributed over the number of pier and span elements located within the waterway, or within the distance of three times the overall length of the design vessel, on each side of the inbound and outbound vessel transit paths if the waterway is wide. This results in an acceptable risk criterion for each pier and span element of the total bridge.

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The design vessel for each pier or span element shall be chosen so that the annual frequency of collapse due to vessels that are equal in size to or larger than the design vessel is less than the acceptable risk criterion specified in Item (a) or (b), as applicable.

A3.3.3 Annual frequency of collapse A3.3.3.1 General The annual frequency of bridge component collapse due to vessel collision, AF, shall be taken as AF = (N)(PA)(PG)(PC) where N = the annual number of vessels, classified by type, size, and loading condition, that use the channel and can hit the bridge component PA

= the probability of vessel aberrancy

PG = the geometric probability of a collision between an aberrant vessel and a bridge pier or span PC

= the probability of bridge collapse due to a collision with an aberrant vessel

AF shall be calculated for each bridge element and vessel classification. The summation of all element AFs equals the annual frequency of collapse for the entire bridge structure.

A3.3.3.2 Probability of aberrancy The probability of vessel aberrancy, PA (the probability that a vessel will stray off course and threaten a bridge) may be determined either by statistical analysis of historical data on vessels transiting the waterway or by the following approximate method: PA = (BR)(RB)(RC)(RXC)(RD) where BR = = RB = RC RXC = = RD

aberrancy base rate (usually taken as 0.6 × 10–4 for ships) correction factor for bridge location correction factor for current acting parallel to vessel transit path correction factor for cross-currents acting perpendicular to vessel transit path correction factor for vessel traffic density

A3.3.3.3 Correction factors 

A3.3.3.3.1 Factor for bridge location Based on the relative location of the bridge in one of three waterway regions, as shown in Figure A3.3.1, the correction factor, RB , shall be as follows: (a) for straight regions: 1.0 (b) for transition regions:

1.0 +

q 90°

(c) for turn/bend regions:

q 45° where  = angle of the turn or bend specified in Figure A3.3.1, degrees 1.0 +

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Turn region 1000 m 1000 m

10

00

m

10

00

Channel

m

Straight region Transition region

q

Transition region

(a) Turn in channel

Bend region 1000 m 10

00

Channel

m

Straight region Transition region

q

Transition region

(b) Bend in channel

Figure A3.3.1 Waterway regions for bridge location (See Clause A3.3.3.1.)

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Pier Vessel

Centreline of vessel transit path

Vessel Aberrant vessel sailing path normal distribution σ = LOA

Vessel/pier Impact zone

PG



Figure A3.3.1A Geometric probability of pier collision (See Clause A.3.3.3.3.5.)

Bridge superstructure

Half-vessel width away from the pier

Centreline of vessel transit path

Aberrant vessel sailing path Normal distribution σ = LOA

PG = Sum of shaded areas



Figure A3.3.1B Geometric probability of superstructure collision (See Clause A.3.3.3.3.5.)

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A3.3.3.3.2 Factor for parallel currents For currents acting parallel to the vessel transit path in the waterway, the correction factor shall be

RC = 1.0 +

VC 5

where VC

= current velocity component parallel to vessel transit path, m/sec

A3.3.3.3.3 Factor for cross-currents For currents acting perpendicular to the vessel transit path in the waterway, the correction factor shall be

RXC = 1.0 +

VXC 2

where VXC

= current velocity component perpendicular to vessel transit path, m/sec

A3.3.3.3.4 Factor for vessel traffic density The correction factor, RD , selected on the basis of the ship traffic density in the waterway in the immediate vicinity of the bridge, shall be (a) 1.0 for low-density traffic, in which vessels rarely meet, pass, or overtake each other in the immediate vicinity of the bridge; (b) 1.3 for average-density traffic, in which vessels occasionally meet, pass, or overtake each other in the immediate vicinity of the bridge; or (c) 1.6 for high-density traffic, in which vessels routinely meet, pass, or overtake each other in the immediate vicinity of the bridge. 

A3.3.3.3.5 Geometric probability The geometric probability, PG, being the conditional probability that an aberrant vessel will hit a bridge component, shall be determined by a normal distribution to model the aberrant vessel sailing path near the bridge. The standard deviation of the normal distribution shall be taken to be equal to the overall length, LOA, of the vessel and mean of the normal distribution shall be located at the centerline of the vessel transit path. Any other distribution shall require Approval. Pier collision — the geometric probability, PG, for collision with a pier shall be taken as the area under the normal distribution curve bounded by the projected pier width perpendicular to the transit path and half width of the vessel on each side of the pier, as shown in Figure A3.3.1A. Superstructure collision — the geometric probability, PG, for collision with superstructure in a span shall be taken as sum of all areas under the normal distribution curve at locations where clearance under the superstructure is insufficient to allow clear passage of the vessel, as shown in Figure A3.3.1B. For the same bridge component, PG shall be calculated for each ship category.

A3.3.3.3.6 Probability of collapse The probability of bridge collapse, PC, once a bridge component has been hit by an aberrant vessel, being based on the ratio of the ultimate lateral resistance of the pier, HP , and span, HS , to the vessel impact force, P, as shown in Figure A3.3.2, shall be calculated as follows: PC = 0.1 + 9(0.1 – H/P) if 0.0  H/P < 0.1

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(1− H/P ) if 0.1  H/P  1.0 9

PC = 0.0 if H/P > 1.0 where H

= ultimate bridge element strength, HP or HS , MN

P

= vessel impact forces, PS , PBH , PDH , or PMT, MN, as specified in Clauses A3.3.5 and A3.3.7

Probability of collapse (PC)

1.0

0.5

0.1 0.1

0.5

1.0

Ultimate bridge element strength (H/P) Vessel impact force

Figure A3.3.2 Probability of collapse distribution (See Clause A3.3.3.3.6.)

A3.3.4 Design collision velocity A3.3.4.1 Transit velocity in channel The vessel transit velocity, VT , shall represent the velocity at which the design vessel is transiting the channel or waterway under normal environmental conditions.

A3.3.4.2 Minimum collision velocity The minimum collision velocity, V min , shall not be less than the yearly mean current velocity at the bridge location. In waterways subject to seasonal flooding, flood flow velocity shall be considered in determining the collision velocity.

A3.3.4.3 Distribution When an aberrant vessel wanders away from the navigation channel, its velocity shall be considered to reduce linearly to the minimum velocity over a distance equal to three times the overall length of the design vessel, as shown in Figure A3.3.3.

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Canadian Highway Bridge Design Code

VT

Vmin 0 0

XC

XL

Distance to bridge element from centreline of vessel transit path (X), m Legend: V = design collision velocity, m/sec VT = typical vessel transit velocity in the channel, m/sec Vmin = minimum collision velocity, m/sec XC = distance to edge of channel from centreline of vessel transit path, m XL = distance equal to three times the overall length of the design vessel from centreline of vessel transit path, m X = distance to bridge element from centreline of vessel transit path, m

Figure A3.3.3 Velocity distribution in channel (See Clause A3.3.4.3.)

A3.3.5 Ship collision force on pier The ship collision impact force shall be taken as PS = (DWT) 0.5 (V/8.4) where = equivalent static vessel collision force, MN

PS

DWT = dead weight tonnage of vessel, t V

= design collision velocity, m/sec

A3.3.6 Vessel collision energy The kinetic energy of a moving vessel to be absorbed during a non-eccentric collision with a bridge pier shall be taken as

KE =

(CH )(W )(V )2 2 × 103

where KE

= vessel collision energy, MN • m

CH

= hydrodynamic mass coefficient

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© Canadian Standards Association

= vessel displacement tonnage, t

The vessel displacement tonnage, W, shall be based on the loading condition of the vessel and shall include the empty weight of the vessel, plus consideration of the weight of cargo, DWT, for loaded vessels, or the weight of water ballast for vessels transiting in an empty or light condition. The following values of CH shall be used: (a) for large under-keel clearances (≥ 0.5 × draft): 1.05; and (b) for small under-keel clearances (≤ 0.1 × draft): 1.25.

A3.3.7 Ship collision force on superstructure A3.3.7.1 Collision with bow The bow collision force on a superstructure shall be taken as PBH = (RBH)(PS) where PBH

= ship bow collision force on an exposed superstructure, MN

RBH

= ratio of exposed superstructure depth to the total bow depth

PS

= ship collision force as specified in Clause A3.3.5, MN

For the purposes of this Clause, exposure shall be the vertical overlap between the vessel and the bridge superstructure within the depth of the collision zone.

A3.3.7.2 Collision with deck house The deck house collision force on a superstructure shall be taken as PDH = (RDH)(PS) where PDH

= ship deck house collision force, MN

RDH

= reduction factor of 0.10 for ships exceeding 100 000 DWT

⎡ DWT ⎤ = reduction factor of 0.20 − ⎢ (0.10) ⎣ 100 000 ⎥⎦ PS

for ships of 100 000 DWT or less

= ship collision force as specified in Clause A3.3.5, MN

A3.3.7.3 Collision with mast The mast collision force on a superstructure shall be taken as PMT = 0.10PDH where PMT

= ship mast collision force, MN

PDH

= ship deck house collision force as specified in Clause A3.3.7.2, MN

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A3.3.8 Application of impact forces A3.3.8.1 Pier design A3.3.8.1.1 Design cases Forces, both parallel and normal to the centreline of the navigable channel, shall be investigated. For pier design, the impact force shall be applied as an equivalent static force. Two design cases shall be considered: (a) 100% of the ship collision force, Ps , applied in a direction parallel to the alignment of the centreline of the navigable channel; and (b) 50% of the ship collision force, Ps , applied normal to the direction of the centreline of the channel. These impact forces shall not be taken to act simultaneously. All portions of the bridge pier exposed to physical contact by any portion of the design vessel’s hull or bow shall be proportioned to resist the applied loads. The bow overhang, rake, or flair distance shall be considered in determining the portions of the pier exposed to contact by the vessel. Crushing of the vessel’s bow causing contact with any setback portion of the pier shall also be considered.

A3.3.8.1.2 Distribution of impact force The impact force from both design cases shall be applied to the pier in accordance with the following requirements: (a) To design the pier for overall stability, the design impact force shall be applied as a concentrated force on the pier at the mean high water level of the waterway, as shown in Figure A3.3.4. (b) To design the pier for local collision forces, the design impact force shall be applied as a vertical line load equally distributed along the ship’s bow depth, as shown in Figure A3.3.5. The ship’s bow shall be considered to be raked forward when the potential contact area of the impact force on the pier is being determined.

A3.3.8.2 Superstructure design For superstructure design, the design impact force shall be applied as an equivalent static force perpendicular to the superstructure member.

PS

Mean high water level

Loaded/ballasted draft

Figure A3.3.4 Ship impact concentrated force on pier (See Clause A3.3.8.1.)

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PS DB

DB

Mean high water level

Loaded/ballasted draft

Figure A3.3.5 Ship impact line load for local collision force on pier (See Clause A3.3.8.1.)

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Annex A3.4 (normative) CL-625-ONT live loading Note: This Annex is a mandatory part of this Code.

A3.4.1 General In Ontario, the CL-625-ONT Truck shown in Figure A3.4.1 and the CL-625-ONT Lane Load shown in Figure A3.4.2 shall be used instead of the CL-625 Truck and CL-W Lane Load, respectively.

Axle no. 1 Wheel loads, kN 25 50 Axle loads, kN

4 87.5 175

3 2 70 70 140 140 3.6 m

1.2 m

5 60 120

6.6 m

6.6 m

18 m

Figure A3.4.1 CL-625-ONT Truck (See Clause A3.4.1.) Uniformly distributed load 9 kN/m Wheel loads, kN Axle loads, kN

20 40

56 56 112 112

3.6 m

1.2 m

70 140

6.6 m

48 96

6.6 m

18 m

Figure A3.4.2 CL-625-ONT Lane load (See Clause A3.4.1.)

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Section 4 — Seismic design 4.1 4.2 4.3 4.3.1 4.3.2 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 4.4.6 4.4.7 4.4.8 4.4.9 4.4.10 4.5 4.5.1 4.5.2 4.5.3 4.6 4.6.1 4.6.2 4.6.3 4.6.4 4.6.5 4.6.6 4.7 4.7.1 4.7.2 4.7.3 4.7.4 4.7.5 4.8 4.8.1 4.8.2 4.8.3 4.8.4 4.8.5 4.9 4.9.1 4.9.2 4.10 4.10.1 4.10.2 4.10.3 4.10.4 4.10.5 4.10.6 4.10.7 4.10.8

Scope 117 Definitions 117 Abbreviation and symbols 119 Abbreviation 119 Symbols 119 Earthquake effects 122 General 122 Importance categories 122 Zonal acceleration ratio 123 Seismic performance zones 123 Analysis for earthquake loads 123 Site effects 125 Elastic seismic response coefficient 126 Response modification factors 127 Load factors and load combinations 128 Design forces and support lengths 128 Analysis 132 General 132 Single-span bridges 132 Multi-span bridges 133 Foundations 134 General 134 Liquefaction of foundation soils 134 Stability of slopes 135 Seismic forces on abutments and retaining walls 135 Soil-structure interaction 135 Fill settlement and approach slabs 135 Concrete structures 135 General 135 Seismic Performance Zone 1 135 Seismic Performance Zone 2 136 Seismic Performance Zones 3 and 4 136 Piles 138 Steel structures 140 General 140 Materials 140 Sway stability effects 140 Steel substructures 140 Other systems 144 Joints and bearings 144 General 144 Seismic design forces 144 Seismic base isolation 144 General 144 Zonal acceleration ratio 145 Seismic performance zones 145 Site effects and site coefficient 145 Response modification factors and design requirements for substructure 145 Analysis procedures 145 Clearance and design displacements for seismic and other loads 148 Design forces for Seismic Performance Zone 1 148

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4.10.9 4.10.10 4.10.11 4.10.12 4.10.13 4.10.14 4.10.15 4.11 4.11.1 4.11.2 4.11.3 4.11.4 4.11.5 4.11.6 4.11.7 4.11.8 4.11.9 4.11.10 4.11.11 4.11.12 4.11.13 4.11.14 4.11.15 4.12 4.12.1 4.12.2 4.12.3 4.12.4

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Design forces for Seismic Performance Zones 2, 3, and 4 148 Other requirements 148 Required tests of isolation system 149 Elastomeric bearings — Design 151 Elastomeric bearings — Construction 152 Sliding bearings — Design 153 Sliding bearings — Construction 153 Seismic evaluation of existing bridges 153 General 153 Bridge classification 153 Damage levels 153 Performance criteria 153 Evaluation methods 153 Load factors and load combinations for seismic evaluation 154 Minimum support length 154 Member capacities 154 Required response modification factor 155 Response modification factor of existing substructure elements 155 Evaluation acceptance criteria 155 Other evaluation procedures 156 Bridge access 156 Liquefaction of foundation soils 156 Soil-structure interaction 156 Seismic rehabilitation 156 Performance criteria 156 Response modification factor for rehabilitation 156 Seismic rehabilitation 156 Seismic rehabilitation techniques 157

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Canadian Highway Bridge Design Code

Section 4 Seismic design 4.1 Scope This Section specifies minimum requirements for (a) the seismic analysis and design of new bridge structures; and (b) the seismic evaluation and rehabilitation of existing bridge structures.

4.2 Definitions The following definitions apply in this Section: Capacity-protected element — a substructure or superstructure element that has a force demand limited by the capacity of the ductile substructure element. Concentrically braced frame with nominal ductility — a braced frame with concentric bracing designed and detailed to absorb limited amounts of energy through inelastic bending or extension of bracing members. Connectors — mechanical devices, including bearing components and shear keys, that provide transverse or longitudinal restraint of movement of the superstructure relative to the substructure. Connectors do not include moment connections, monolithic joints, or longitudinal restrainers at expansion bearings (see Clause 4.4.10.4.2). Damping — the dissipation of energy of a structure oscillating in one of its natural modes of vibration. It is normally expressed as a ratio of the actual value of damping to the critical value of damping. The critical value of damping is the minimum damping at which an initial motion decays without oscillation. Design displacement — the minimum lateral seismic displacement at the centre of rigidity required for design of the isolation system (see Clause 4.10.7). Ductile concentrically braced frame — a braced frame with concentric bracing designed and detailed to absorb energy through yielding of the braces. Ductile substructure element — an element of a substructure that is expected to undergo reversed-cyclic inelastic deformations without significant loss of strength and is detailed to develop the appropriate level of ductility while remaining stable. Ductility — the ability of a structural member to deform without significant loss of load-carrying capacity after yielding. Effective damping — the value of equivalent viscous damping corresponding to the energy dissipated during cyclic response at the design displacement of the isolation system. Effective stiffness — the value of the lateral force in the isolation system, or an element thereof, divided by the corresponding lateral displacement. Effective weight — the total unfactored dead load of a superstructure and the portion of substructure elements that contribute to the inertial mass.

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Elastic restraint system — the collection of structural elements that provides restraint of a seismically isolated structure for non-seismic lateral loads. The elastic restraint system may be either an integral part of isolator units or a separate device. Emergency-route bridge — a bridge as specified in Clause 4.4.2. Factored load — the product of a load specified in this Code and the corresponding load factor. Factored load effect — the load effect caused by a factored load. Factored resistance — the resistance of a member calculated using the appropriate material resistance factors. Flexural frequency — a natural frequency of vibration of an unloaded bridge based on the flexural stiffness and mass distribution of the superstructure. Hoop — a closed tie or continuously wound tie with seismic hooks at each end. Isolation system — the collection of structural elements that includes all individual isolator units, all structural elements that transfer force between elements of the isolation system, and all connections to other structural elements. The isolation system also includes the elastic restraint system if such a system is used to meet the design requirements of Clause 4.10. Isolator unit — a device used for seismic base isolation (see Clause 4.10). Lateral restoring force — a lateral force that tends to restore the isolator unit to its original position. Lifeline bridge — a bridge as specified in Clause 4.4.2. Natural frequency — the frequency of vibration of one of the natural modes of a bridge, expressed in cycles per second. The natural frequency is the inverse of the natural period. Natural period — the duration of one complete cycle of free vibration of one of the normal modes of vibration. Nominal resistance — the resistance of a member, connection, or structure based on the specified material properties and the nominal dimensions and details of the final section(s) chosen, calculated with all material resistance factors taken as 1.0. Normal mode shape — the geometric configuration of a structure vibrating at one of the associated natural frequencies. Panel zone — the area of beam-to-column connection delineated by beam and column flanges. Probable resistance — the resistance of a member, calculated by taking into account the expected development of large strains and associated stresses larger than the minimum specified yield values taken as the nominal resistance times a factor greater than 1.0 (see Clause 4.4.10.4.3) Regular bridge — a bridge as specified in Clause 4.4.5.3.2. Response modification factor — a factor specified in Clauses 4.4.8.1, 4.11.9, and 4.12.2. Response spectrum — the envelope of maximum response of a single degree-of-freedom oscillator subjected to a particular disturbance, plotted as a function of the natural period or frequency of the oscillator. Restrainer — a tie, cable, or other device designed for limiting displacements at expansion bearings.

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Return period — the average time in years between the equalling or exceeding of an event. The inverse of the return period is approximately the probability of equalling or exceeding the event in one year. Seismic cross-tie — a single bar with a seismic hook at one end and, at the other end, a hook with a bend of at least 90° and at least a 12-bar diameter extension. Seismic hook — a hook with a bend of at least 135° and an extension of not less than the larger of ten bar diameters or 150 mm. Static pushover analysis — a static analysis involving a step-by-step force-deformation analysis procedure accounting for inelastic effects. Time-history analysis — a dynamic analysis obtained by determining the response using a step-by-step integration of an acceleration-time seismic ground response. Total design displacement — the maximum lateral seismic displacement of an isolator for the testing requirements of an isolation system (see Clause 4.10.7).

4.3 Abbreviation and symbols 4.3.1 Abbreviation The following abbreviation applies in this Section: PHA — Peak horizontal ground acceleration, g

4.3.2 Symbols The following symbols apply in this Section: A

= zonal acceleration ratio (dimensionless)

Ab

= bonded area of rubber

Ac

= area of core of a spirally reinforced compression member measured out-to-out of spirals, mm2

Ag

= gross cross-sectional area, mm2

Ar

= reduced net bonded area of rubber, Ab (1 – Δ /B)

Ash

= total cross-sectional area of tie reinforcement, including supplementary cross-ties with a vertical spacing of s and crossing a section with a core dimension of hc, mm2

B

= numerical coefficient related to the effective damping of the isolation system as specified in Table 4.8; the plan dimension in loaded direction of rectangular bearing or diameter of circular bearing

b

= width of the compression face of the member, mm

bbf

= width of the beam flange

C

= member reserve capacity calculated in accordance with Clause 4.11.9

Cf

= factored compressive force in column

Cr

= factored compressive resistance of column (see Clause 10.9.3)

Csm

= elastic seismic response coefficient for the mth mode of vibration (dimensionless)

D

= dead load, as defined in Clause 3.2

d

= effective depth, being the distance from the extreme compression fibre to the centroid of the tensile force, mm; depth of column

db

= nominal bar diameter

di

= design displacement at the centre of rigidity of the isolation system in the direction under consideration; lateral displacement under earthquake loads

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= modulus of elasticity of elastomer

EQ

= earthquake load, expressed as a modified design force (see Clauses 4.4.10.3.2 and 4.4.10.4.2)

F

= statically equivalent seismic force

FA

= design force for connections for bridges in Seismic Performance Zone 1

Fn

= maximum negative force in an isolator unit during a single cycle of prototype testing at a displacement amplitude of Δ n

Fn,min

= minimum negative force in an isolator unit for all cycles of prototype testing at a common displacement amplitude of Δ n

Fp

= maximum positive force in an isolator unit during a single cycle of prototype testing at a displacement amplitude of Δ p

Fp,min

= minimum positive force in an isolator unit for all cycles of prototype testing at a common displacement amplitude of Δ p

Fy

= specified minimum yield stress, MPa

fc’

= specified compressive strength of concrete, MPa

fcr

= cracking strength of concrete, MPa

fy

= minimum specified yield strength of reinforcing bars, MPa

g

= acceleration due to gravity

H

= for abutments, the average height of the columns supporting the bridge deck to the next expansion joint, mm; for columns or piers, the column or pier height, mm; for hinges within a span, the average height of the two adjacent columns or piers, mm Note: The value of H for single-span bridges is 0.0.

hc

= core dimension of a tied column in the direction under consideration, mm

I

= importance factor (dimensionless)

K

= bridge lateral stiffness; modification factor specified in Table 4.6

k

= material constant

keff

= effective stiffness of an isolator unit, determined by prototype testing

kmax

= maximum effective stiffness of an isolation system at the design displacement in the horizontal direction under consideration

kmin

= minimum effective stiffness of an isolation system at the design displacement in the horizontal direction under consideration

L

= length of the bridge deck to the adjacent expansion joint or to the end of the bridge deck, mm Note: For hinges within a span, L is the sum of the distances to either side of the hinge. For single-span bridges, L is the length of the bridge deck (see Figure 4.1).

L/r

= slenderness ratio of brace

Mpr

= probable flexural resistance of column

Mpx

= plastic moment resistance in strong direction of bending

m

= mass per unit length of a structure, kg/m

N

= minimum support length measured normal to the face of the abutment or pier, mm

n

= natural frequency of vibration, Hz

P

= maximum vertical load resulting from the combination of dead load plus live load (including seismic live load, if applicable) using a γ factor of 1.0

Pe

= equivalent uniformly distributed static seismic loading in uniform-load method (see Clause 4.5.3.1)

pe (x)

= equivalent static earthquake loading applied to represent the primary mode of vibration, kN/m

Pf

= factored axial load at a section at the ultimate limit state, N

po

= arbitrary uniform lateral load

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R

= response modification factor (dimensionless)

Rreq

= required response modification factor (see Clause 4.11.9)

Rprov

= provided response modification factor (see Clause 4.11.10)

ry

= radius of gyration of a member about its weak axis

S

= dimensionless site coefficient (see Clause 4.4.6); shape factor of an elastomeric bearing (see Clauses 4.10.12.2 and 11.2)

Se

= seismic force effect (see Clause 4.11.9)

Si

= dimensionless site coefficient for isolation design for the given soil profile, as specified in Clause 4.10.4

s

= vertical spacing of transverse reinforcement

T

= natural period of a structure, s

Te

= period of seismically isolated structure, s, in the direction under consideration

Tm

= period of vibration of the mth mode, s

t

= thickness of flange

Vc

= factored shear resistance provided by tensile stresses in the concrete, N

Vf

= factored shear force at a section, N

Vr

= factored shear resistance; factored shear resistance of column web

Vs,max = maximum value of Vs (x) Vs (x)

= deformation corresponding to po

W

= effective weight of a bridge Note: For design of the isolation system, W is the total seismic dead load weight of the structure above the isolation interface.

W(x)

= dead load of the bridge superstructure and tributary substructure, expressed in weight per unit length of the bridge

w

= web thickness

α β

= generalized participation factor used in the single-mode spectral method

γ Δ Δc Δn Δp Δs εc ε eq ε sc ε sh

= generalized mass factor used in the single-mode spectral method, kN-m2

ε sr εu θ λ ρh

= shear strain due to imposed rotation

= equivalent viscous damping ratio for the isolation system; generalized participation factor used in the single-mode spectral method, kN-m = shear deflection in the bearing = instantaneous compressive deflection = maximum negative displacement of an isolator unit during each cycle of prototype testing = maximum positive displacement of an isolator unit during each cycle of prototype testing = imposed lateral displacement = compression strain in bearing due to vertical loads = shear strain due to di = shear strain due to vertical loads = shear strain due to maximum horizontal displacement resulting from creep, post-tensioning, shrinkage, and thermal effects calculated between the installation temperature and the least favourable extreme temperature = minimum elongation-at-break of rubber = rotation imposed on bearing = slenderness parameter (see Clause 10.9.3) = ratio of area of horizontal shear reinforcement to gross concrete area of a vertical section

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ρs

= ratio of volume of spiral reinforcement to total volume of core, out-to-out of spirals of spirally reinforced compression members

ρv Σ keff

= ratio of area of vertical shear reinforcement to gross concrete area of a horizontal section

φc φs ψ

= resistance factor for concrete, as specified in Clause 8.4.6

= sum of the effective linear stiffnesses of all bearings and substructures supporting the superstructure segment, calculated at displacement di = resistance factor for structural steel (see Clause 10.5.7) or reinforcing steel (see Clause 8.4.6) = skew of support measured from a line normal to the span direction, degrees

4.4 Earthquake effects 4.4.1 General Force effects arising from horizontal earthquake motions shall be determined in accordance with Clause 4.4.5 on the basis of the elastic seismic response coefficient, Csm , specified in Clause 4.4.7 and the effective weight of the bridge. Seismic design force effects for ductile substructure elements shall be adjusted by the response modification factors specified in Clause 4.4.8.1 and designed and detailed in accordance with Clauses 4.7 and 4.8. Displacements shall be determined using a response modification factor of 1.0 and an importance factor of 1.0. Force effects arising from vertical earthquake motions shall be considered accounted for by using the load factors on dead loads specified in Table 3.2. Earthquake load effects for capacity-protected members shall be determined from elastic design forces or in accordance with capacity design principles for forces resulting from inelastic action of members with which they connect. Special bridges such as arches, cable-supported structures, and large trusses require special studies and shall be designed using seismic-resistant design principles providing a minimum level of safety comparable to that intended in this Code. Soil liquefaction, liquefaction-induced ground movements, slope instability, increases in lateral earth pressure, soil-structure interaction, and approach fill settlements shall be considered in accordance with Clause 4.6.

4.4.2 Importance categories For the purpose of Clause 4.4, the Regulatory Authority shall place bridges into one of the following three importance categories: (a) lifeline bridges; (b) emergency-route bridges; and (c) other bridges. The basis of classification shall include social/survival and security/defence requirements. In classifying a bridge, consideration shall be given to possible future changes in conditions and requirements. Lifeline bridges are generally those that carry or cross over routes that need to remain open to all traffic after the design earthquake, which is an event with a 10% probability of exceedance in 50 years (equivalent to a 15% probability of exceedance in 75 years and a return period of 475 years). Lifeline bridges also need to be usable by emergency vehicles and for security/defence purposes immediately after a large earthquake, e.g., a 1000-year return period event (7.5% probability of exceedance in 75 years). Emergency-route bridges are generally those that carry or cross over routes that should, at a minimum, be open to emergency vehicles and for security/defence purposes immediately after the design earthquake.

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4.4.3 Zonal acceleration ratio The zonal acceleration ratio, A, to be used in the application of Clause 4.4 shall be determined in accordance with one of the following Tables, except that a qualified specialist shall be consulted to determine the zonal acceleration ratio for sites located close to active faults or with PHA values greater than 0.40: (a) Table A3.1.1 (for locations not listed in Table A3.1.1, the highest value for adjacent locations listed in the Table shall be used unless site-specific data is obtained); or (b) Table 4.1, using the PHA specified in Figure A3.1.6 or as provided by the Geological Survey of Canada using the seismic hazard methodology used to generate Figure A3.1.6.

4.4.4 Seismic performance zones Bridges shall be assigned to one of the four seismic performance zones specified in Table 4.1 using the zonal acceleration ratio, A, obtained from Clause 4.4.3.

Table 4.1 Seismic performance zones (See Clauses 4.4.3, 4.4.4, 4.6.6, 4.10.2, 4.10.3, and 4.10.6.2.1.) Seismic performance zone Range of PHA, g, for 10% probability of exceedance in 50 years

Zonal acceleration ratio, A

Lifeline bridges (see Clause 4.4.2(a))

Emergency-route and other bridges (see Items (b) and (c) of Clause 4.4.2)

0.00 ≤ PHA < 0.04 0.04 ≤ PHA < 0.08 0.08 ≤ PHA < 0.11 0.11 ≤ PHA < 0.16 0.16 ≤ PHA < 0.23 0.23 ≤ PHA < 0.32 0.32 or greater

0 0.05 0.1 0.15 0.2 0.3 0.4

2 2 3 3 3 4 4

1 1 2 2 3 4 4

4.4.5 Analysis for earthquake loads 4.4.5.1 General The minimum analysis requirements for seismic effects shall be as specified in Clauses 4.4.5.2 and 4.4.5.3. For the modal methods of analysis specified in Clause 4.4.5.3, the elastic design spectrum shall be that given by the equation in Clause 4.4.7.1. Bridges in Seismic Performance Zone 1 need not be analyzed for seismic loads, regardless of their importance and geometry. However, the minimum requirements specified in Clauses 4.4.10.2 and 4.4.10.5 shall apply. Details for analysis of dynamic effects are specified in Clause 4.5.

4.4.5.2 Single-span bridges 4.4.5.2.1 Analysis requirements Seismic analysis shall not be required for single-span bridges regardless of seismic performance zone, except that single-span truss bridges in Seismic Performance Zones 2, 3, and 4 shall be analyzed as specified for regular multi-span bridges in Clause 4.4.5.3.

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4.4.5.2.2 Other requirements Connectors and restrainers between the superstructure and the abutments shall be designed for the minimum force requirements specified in Clause 4.4.10.1. Single-span truss bridges in Seismic Performance Zones 2, 3, and 4 shall be designed for the elastic forces (R = 1.0). For all seismic zones, end diaphragms in girder bridges shall be designed to remain elastic while transmitting forces equal to the connection forces specified in Clause 4.4.10. Minimum support length requirements shall be satisfied at each abutment as specified in Clause 4.4.10.5. For Seismic Performance Zones 2, 3, and 4, the applicable requirements of Clause 4.6 shall be satisfied.

4.4.5.3 Multi-span bridges 4.4.5.3.1 Analysis requirements For multi-span structures, the minimum analysis requirements shall be as specified in Table 4.2. Bridges may also be analyzed using an inelastic analysis such as a time-history analysis (see Clause 4.5.3.4) or a static pushover analysis (see Clause 4.5.3.5). Care needs to be taken with the modelling of the structure, selection of the input time histories, and interpretation of the results. The seismic analysis of earthquake load effects for multi-span trusses and the diaphragms of girder bridges in Seismic Performance Zones 2, 3, and 4 shall also include an assessment of earthquake load effects on the superstructure components. The analysis requirements shall be as specified in Table 4.2 and shall be based on an appropriate global model of the superstructure and substructure. The response modification factors and design requirements specified in Clauses 4.4.8 and 4.4.10 shall also apply.

Table 4.2 Minimum analysis requirements for multi-span bridges (See Clauses 4.4.5.3.1 and 4.10.6.1.) Seismic performance zone

Lifeline bridges

Emergency-route bridges

Other bridges

Regular

Irregular

Regular

Irregular

Regular

Irregular

1

—

—

No eismic analysis required (see Clause 4.4.5.1)

No sseismic analysis required (see Clause 4.4.5.1)

No seismic analysis required (see Clause 4.4.5.1)

No seismic analysis required (see Clause 4.4.5.1)

2

MM

MM

UL

MM

UL

SM

3

MM

TH*

MM

MM

UL

MM

4

MM

TH*

MM

MM

SM

MM

*Requires Approval. The multi-mode method may be used if appropriate. Legend: MM = multi-mode spectral method (see Clause 4.5.3.3) SM = single-mode spectral method (see Clause 4.5.3.2) TH = time-history method (see Clause 4.5.3.4) UL = uniform-load method (see Clause 4.5.3.1)

4.4.5.3.2 Regular and irregular bridges A bridge shall be considered regular if it has fewer than seven spans, no abrupt or unusual changes in weight, stiffness, or geometry, and no large changes in these parameters from span to span or support to support (abutments excluded) as specified in Table 4.3. All other bridges shall be considered irregular.

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Table 4.3 Regular bridge requirements (See Clause 4.4.5.3.2.) Number of spans 2

3

4

5

6

Maximum subtended angle (curved bridge)

90°

90°

90°

90°

90°

Maximum span length ratio from span to span

3

2

2

1.5

1.5

Continuous superstructure or multiple simple spans with longitudinal restrainers and transverse restraint at each support or a continuous deck slab

—

4

4

3

2

Multiple simple spans without restrainers or a continuous deck slab

—

1.25

1.25

1.25

1.25

Maximum bent or pier stiffness ratio from span to span (excluding abutments)

Note: All ratios are expressed in terms of the smaller value.

4.4.6 Site effects 4.4.6.1 General The effects of site conditions on bridge response shall be included in the determination of seismic loads for bridges. The site coefficient, S, specified in Table 4.4, shall be based on the soil profile types specified in Clauses 4.4.6.2 to 4.4.6.5. Subject to the requirements of Clause 4.4.6.6, a site coefficient need not be explicitly identified if a site-specific seismic response coefficient is developed by a qualified specialist.

Table 4.4 Site coefficient, S (See Clauses 4.4.6.1 and 4.4.6.6.) Soil profile type

Site  coefficient, S

I

1.0

II

1.2

III

1.5

IV

2.0

4.4.6.2 Soil Profile Type I Soil Profile Type I is a profile with (a) rock of any characteristic, shale-like or crystalline in nature (such material can be characterized by a shear wave velocity greater than 750 m/s or by another appropriate means of classification); or (b) stiff soil conditions where the soil depth is less than 60 m and the soil types overlying rock are stable deposits of sands, gravels, or stiff clays.

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4.4.6.3 Soil Profile Type II Soil Profile Type II is a profile with stiff clay or deep cohesionless soils where the soil depth exceeds 60 m and the soil types overlying rock are stable deposits of sands, gravels, or stiff clays.

4.4.6.4 Soil Profile Type III Soil Profile Type III is a profile with soft to medium-stiff clays and sands, characterized by 9 m or more of soft to medium-stiff clays with or without intervening layers of sand or other cohesionless soils.

4.4.6.5 Soil Profile Type IV Soil Profile Type IV is a profile with soft clays or silts greater than 12 m in depth. These materials can be characterized by a shear wave velocity less than 150 m/s and can include loose natural deposits or non-engineered fill.

4.4.6.6 Other soil profile types For other soil profile types, or where the soil properties are not known in sufficient detail to determine the soil profile type with confidence, the Engineer shall use his or her judgment to select a site coefficient from Table 4.4 that conservatively represents the amplification effects at the site. The soil profile coefficients shall apply to all foundation types, including pile-supported and spread footings.

4.4.7 Elastic seismic response coefficient 

4.4.7.1 General Unless otherwise specified in Clause 4.4.7.2, the elastic seismic response coefficient, Csm , for the mth mode of vibration shall be

C sm =

1.2AIS ≤ 2.5AI Tm2 / 3

where A = zonal acceleration ratio specified in Clause 4.4.3 S Tm I

= = = =

site coefficient specified in Clause 4.4.6 period of vibration of the mth mode, s importance factor based on the importance category specified in Clause 4.4.2 3.0 for lifeline bridges, but need not be taken greater than the value of R for the ductile substructure elements specified in Table 4.5 = 1.5 for emergency-route bridges = 1.0 for other bridges

4.4.7.2 Exceptions The following exceptions shall apply: (a) For Soil Profile Type III or Type IV soils in areas where the zonal acceleration ratio is equal to or greater than 0.30, Csm need not exceed 2.0AI. (b) For Soil Profile Type III or Type IV soils, Csm for modes other than the fundamental mode that have periods less than 0.3 s shall be taken as Csm = AI (0.8 + 4.0Tm) (c) For structures in which the period of vibration of any mode exceeds 4.0 s, the value of Csm for that mode shall be taken as

C sm =

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4.4.7.3 Site-specific elastic response coefficient Site-specific response spectra may be used with Approval, except that the response spectra ordinates shall not be less than 0.8Csm .

4.4.8 Response modification factors 4.4.8.1 General The seismic design force effects for the ductile substructure elements shall be determined by dividing the force effects resulting from elastic analysis by the appropriate response modification factor, R, specified in Table 4.5. Response modification factors depend on the ability of the ductile substructure element to develop an appropriate level of ductility and energy absorption and shall be used only when all of the design and detailing requirements specified in Table 4.5 are satisfied for the element. The lateral load-resisting substructure elements shall be designed and detailed to be ductile, i.e., have a minimum R of 2.0. For bridges of slab, beam-girder, or box girder construction with a structurally continuous reinforced concrete deck from pier to pier (or abutment to abutment), a detailed analysis of earthquake effects on superstructure components shall not be required. However, an analysis of cross-frames or diaphragms between girders at the abutments and piers shall be required.

Table 4.5 Response modification factor, R (See Clauses 4.4.7.1, 4.4.8.1, 4.4.10.4.2, and 4.12.2.)

Ductile substructure elements

Response modification factor, R

Wall-type piers in direction of larger dimension

2.0

Reinforced concrete pile bents Vertical piles only With batter piles

3.0 2.0

Single columns Ductile reinforced concrete Ductile steel

3.0 3.0

Steel or composite steel and concrete pile bents Vertical piles only With batter piles

5.0 3.0

Multiple-column bents Ductile reinforced concrete Ductile steel columns or frames

5.0 5.0

Braced frames Ductile steel braces Nominally ductile steel braces

4.0 2.5

Note: See Clauses 4.7 and 4.8 for design and detailing requirements.

4.4.8.2 Application Seismic forces shall be assumed to act in any horizontal direction. The appropriate R-factor shall be used for each orthogonal axis of the substructure. A wall-type concrete pier may be analyzed as a single column in the weak direction of the pier if all of the requirements for columns specified in Clause 4.7.4.2 are satisfied.

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4.4.9 Load factors and load combinations 4.4.9.1 General The load factors and load combinations shall be in accordance with Clause 3.5. The earthquake load, EQ, shall be determined in accordance with Clause 4.4.9.2.

4.4.9.2 Earthquake load cases Unless otherwise specified in Clause 4.4.9.3, the elastic seismic effects on each of the principal axes of a component resulting from analyses in the two perpendicular horizontal directions shall be combined to form two load cases as follows: (a) 100% of the absolute value of the effects resulting from an analysis in one of the perpendicular directions combined with 30% of the absolute value of the force effects from the analysis in the second perpendicular direction; and (b) 100% of the absolute value of the effects from the analysis in the second perpendicular direction combined with 30% of the absolute value of the force effects resulting from the analysis in the first perpendicular direction. The effects of vertical ground motion shall be accounted for by using the load factors on dead load specified in Table 3.2.

4.4.9.3 Time-history analysis For spectrum-compatible time-histories in accordance with Clause 4.5.3.4, separate analyses shall be carried out in the two perpendicular directions and the resulting forces shall be combined in accordance with Clause 4.4.9.2. For a time-history analysis using site-specific acceleration time-histories in which the two horizontal ground motion components are considered simultaneously, the resulting forces need not be combined as specified in Clause 4.4.9.2. The effects of vertical ground motion shall be accounted for by using the load factors on dead loads specified in Table 3.2 or by using a site-specific vertical acceleration time-history.

4.4.10 Design forces and support lengths 4.4.10.1 General For single-span bridges in any seismic performance zone, the minimum design connection force effect in the restrained directions between the superstructure and the substructure shall be the tributary dead load at the abutment multiplied by the zonal acceleration ratio and the site coefficient for the site (with a minimum value of A = 0.05). This force shall be considered to act in each horizontally restrained direction. For multi-span bridges, the applicable requirements of Clauses 4.4.10.2 to 4.4.10.7 shall be satisfied. For all bridges, the minimum support lengths at expansion bearings shall be in accordance with Clause 4.4.10.5. Alternatively, longitudinal restrainers shall be provided in accordance with Clause 4.4.10.6.

4.4.10.2 Seismic Performance Zone 1 Where transverse or longitudinal restraint of the superstructure is provided relative to the substructure, the restraining element shall be designed to resist a horizontal seismic force in each restrained direction equal to (a) 0.10 times the tributary dead load, for A = 0.0; or (b) 0.20 times the tributary dead load, for A = 0.05. For each uninterrupted segment of a superstructure, the tributary dead load at the line of fixed bearings used to determine the longitudinal connection force shall be the total dead load of the segment. If each bearing supporting an uninterrupted segment or simply supported span is restrained in the transverse direction, the tributary dead load used to determine the transverse connection design force shall be the dead load reaction at that bearing.

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4.4.10.3 Seismic Performance Zone 2 4.4.10.3.1 General Structures in Seismic Performance Zone 2 shall be analyzed in accordance with the minimum requirements specified in Clause 4.4.5.

4.4.10.3.2 Modified seismic design forces The modified seismic design forces for Zone 2 shall be determined in accordance with the requirements of Clause 4.4.10.4, except that the nominal resistance of the ductile substructure elements shall be used instead of their probable resistance.

4.4.10.4 Seismic Performance Zones 3 and 4 4.4.10.4.1 General Structures in Seismic Performance Zones 3 and 4 shall be analyzed in accordance with the minimum requirements specified in Clause 4.4.5.

4.4.10.4.2 Modified seismic design forces For load effects in ductile substructure elements, seismic design forces, e.g., moments in columns, piers, and pile bents or axial forces in braces, shall be determined by dividing the elastic seismic forces obtained in accordance with Clause 4.4.9.2 by the appropriate response modification factor, R, specified in Table 4.5. The seismic design forces so determined shall be termed modified seismic design forces. Seismic design forces for capacity-protected elements, e.g., superstructures, cap-beams, beam-column joints, and foundations (including footings, pile caps, and piles, but not including pile bents and retaining walls), shall be determined using elastic design forces obtained in accordance with Clause 4.4.9, with R = 1.0 and I = 1.0. Alternatively, capacity-protected elements may be designed to have factored resistances equal to or greater than the maximum force effects that can be developed by the ductile substructure element(s) attaining their probable resistance. Connectors shall be designed to transmit, in their restrained directions, the maximum force effects determined from 1.25 times the elastic seismic forces (R = 1.0 and I = 1.0), but these forces need not exceed the force that can be developed by the ductile substructure element attaining 1.25 times its probable resistance.

4.4.10.4.3 Yielding mechanisms and design forces in ductile substructures The yielding mechanism shall be considered to form prior to any other failure mode due to overstress or instability in the structure and/or in the foundation. Except for pile bents, yielding shall be permitted in ductile substructure elements such as columns, piers, or braces only at locations where the elements can be readily inspected and/or repaired. The nominal and probable resistances shall be determined for the final details of the member chosen and hence may be somewhat larger than the resistance required from the design procedure. For yielding mechanisms involving flexural hinging in ductile substructure elements such as columns, piers, and bents, inelastic hinging moments shall be taken as their probable resistance determined by multiplying the flexural nominal resistance of concrete sections by 1.30 and of steel sections by 1.25. The shear and axial design forces for columns, piers, and pile bents due to earthquake effects shall be as follows: (a) Shear forces: either the unreduced elastic design shear determined in accordance with Clause 4.4.10.4.2, with R = 1.0, or the shear corresponding to inelastic hinging of the column determined from statics that take into consideration the probable flexural resistance of the member and its effective height. For flared columns and columns adjacent to partial-height walls, the top and

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bottom flares and the height of the walls shall be considered in determining the effective column height. If the column foundation is significantly below ground level, the possibility of the hinge forming above the foundation shall be considered. (b) Axial forces: either the unreduced elastic design axial force determined in accordance with Clause 4.4.10.4.2 (using an R-factor of 1.0) or the axial force corresponding to inelastic hinging of the column in a bent.

4.4.10.4.4 Undesirable failure modes and design forces in ductile substructure elements Ductile substructure elements shall be designed so that undesirable failure modes such as shear failures in concrete columns and local buckling of steel columns or braces are avoided.

4.4.10.5 Minimum support length requirements for displacements Unless longitudinal restrainers in accordance with Clause 4.4.10.6 are provided, bridge support lengths at expansion bearings shall accommodate the greater of the maximum displacement calculated in accordance with Clause 4.4.5 (with R = 1.0) and the empirical support length, N, calculated in accordance with this Clause. Bearings restrained for longitudinal movement shall be designed in accordance with Clause 4.4.10.1, 4.4.10.2, 4.4.10.3.2, or 4.4.10.4.2. The empirical support length, N, shall be the minimum support length in millimetres measured normal to the face of the abutment or pier (excluding the concrete cover) and shall be calculated as follows:

y2 ⎤ L H ⎤⎡ ⎡ N = K ⎢200 + + ⎢1+ ⎥ ⎥ 600 150 ⎦ ⎣ 8000 ⎦ ⎣ where K

= modification factor specified in Table 4.6

L

= the length of the bridge deck to the adjacent expansion joint or to the end of the bridge deck, mm (see Figure 4.1) = for hinges within a span, the sum of the distances to either side of the hinge, mm = for single-span bridges, the length of the bridge deck, mm

H

= for abutments, the average height of the columns supporting the bridge deck to the next expansion joint, mm = for columns or piers, the column or pier height, mm = for hinges within a span, the average height of the two adjacent columns or piers, mm = for single-span bridges, 0.0 mm

ψ

130

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L1

L

L2

N1

N

Abutment

N2

Column or pier

L2

L1

N

Joint within a span

Figure 4.1 Dimensions for minimum support lengths (See Clause 4.4.10.5.) 

Table 4.6 Modification factor, K (See Clause 4.4.10.5.)

Seismic performance zone

Zonal acceleration ratio

Soil profile type

Modification factor, K

1

0

I or II

0.5

1

0

III or IV

1.0

1

0.05

All

1.0

2

All applicable

All

1.0

3

All applicable

All

1.5

4

All applicable

All

1.5

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4.4.10.6 Longitudinal restrainers Restrainers shall be designed to ensure integrity under excessive forces or movements without experiencing brittle failures. Friction shall not be considered to be an effective restrainer. Restrainers shall be designed for a force calculated as three times the zonal acceleration ratio, A, multiplied by the dead load of the lighter of the two adjoining spans or parts of the structure, but the factor 3A shall not be less than 0.2. If the restrainer is at a point where relative displacement of sections of the superstructure will occur due to effects such as temperature change and shrinkage, sufficient slack shall be provided in the restrainer so that the restrainer does not restrict such movements. Where restrainers are to be provided at columns or piers, the restrainer of each span may be attached to the column or pier rather than interconnecting adjacent spans. Where a column or pier could be subject to instability due to ground liquefaction or excessive ground movements, the restrainer shall be attached to the column or pier. The connections of a restrainer to the superstructure or substructure shall be designed to resist 125% of the ultimate restrainer capacity. Restrainers shall be designed to remain elastic under the design seismic forces specified in this Section.

4.4.10.7 Hold-down devices For bridges in Seismic Performance Zones 2, 3, and 4, hold-down devices shall be provided at supports and at hinges where the vertical force effect resulting from the seismic load cases specified in Clause 4.4.9.2 or 4.4.9.3 opposes and exceeds 50% but is less than 100% of the reaction due to dead loads. In this case, the net upward force for the design of the hold-down device shall be taken as 10% of the reaction due to dead loads that would be exerted if the span were simply supported. If the vertical seismic forces result in net uplift, the hold-down device shall be designed to resist the larger of (a) 120% of the difference between the vertical seismic force and the reaction due to dead loads; and (b) 10% of the reaction due to dead loads that would be exerted if the span were simply supported.

4.5 Analysis 4.5.1 General The minimum analysis requirements for seismic effects are specified in Clauses 4.4.5.2 and 4.4.5.3. The four types of analysis are described in Clauses 4.5.3.1 to 4.5.3.4. In the analysis methods specified in Clause 4.5.3, the actual weight shall be taken as the effective weight. In the modelling of reinforced concrete sections, either uncracked or cracked cross-sectional properties shall be used when the periods and force effects are calculated. The effects of cracking shall be taken into account in calculating deflections. For the modal methods specified in analysis specified in Clauses 4.5.3.2 and 4.5.3.3, the elastic design spectrum shall be in accordance with Clause 4.4.7. Bridges in Seismic Performance Zone 1 need not be analyzed for seismic loads, regardless of their importance and geometry. However, the minimum requirements specified in Clauses 4.4.10.2 and 4.4.10.5 shall apply.

4.5.2 Single-span bridges Seismic analysis of single-span bridges shall not be required, regardless of seismic zone, except as required by Clause 4.4.5.2.1.

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4.5.3 Multi-span bridges 4.5.3.1 Uniform-load method The uniform load method is applicable to both transverse and longitudinal earthquake motions. The equivalent uniformly distributed static seismic loading, Pe , shall be taken as

C smW L where W = effective weight of the bridge L = total length of the bridge In determining Csm from Clause 4.4.7.1, the period of vibration of the bridge, T, shall be taken as Pe =

W gK

T = 2π

where g = acceleration due to gravity, m/s2 K

= lateral stiffness of the bridge

=

poL Vs,max

where Vs,max = maximum static displacement of the bridge due to an arbitrary uniform lateral load, po 

4.5.3.2 Single-mode spectral method The single-mode spectral method of analysis shall be based on the fundamental mode of vibration in either the longitudinal or transverse direction, as appropriate. This mode shape may be found by applying a uniform horizontal load to the structure and calculating the corresponding deformed shape. The natural period may be calculated by equating the maximum potential and kinetic energies associated with the fundamental mode shape or by a more rigorous dynamic analysis. The amplitude of the displaced shape may be found from the elastic seismic response coefficient, Csm , specified in Clause 4.4.7.1 and the corresponding spectral displacement. This amplitude shall be used to determine force effects. The intensity of the equivalent static seismic loading, pe (x), shall be taken as

pe ( x ) = where

bC sm W ( x )Vs ( x ) g

∫W ( x )Vs ( x ) dx



=

Csm

= elastic seismic response coefficient in Clause 4.4.7.1

Vs

= deformation corresponding to po



where po = an arbitrary uniform lateral load 2 = ∫ W ( x )Vs ( x )dx

W(x) = effective weight of the bridge

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In determining Csm , the period of vibration of the bridge, T, shall be taken as

T = 2p

g po ga

where



=

∫ Vs (x ) dx

4.5.3.3 Multi-mode spectral method The multi-mode spectral method of analysis shall be used for bridges in which coupling occurs in more than one of the three coordinate directions within each mode of vibration. A three-dimensional model shall be used to represent the structure. The number of modes used in the analysis shall be such that 90% mass participation of the superstructure in the direction under consideration is accounted for. The elastic seismic response spectrum specified in Clause 4.4.7 shall be used for each mode. The member forces and displacements shall be estimated using an accepted modal combination procedure. For bridges with closely spaced modes (within 10% of each other in terms of natural frequency), the complete quadratic combination (CQC) method or the absolute sum of the modal quantities shall be used.

4.5.3.4 Time-history method The time-histories of input acceleration used to describe the earthquake loads shall be selected in consultation with the Regulatory Authority. Unless the Regulatory Authority otherwise directs, five spectrum-compatible time histories shall be used when site-specific time-histories are not available. The spectrum used to generate these five time-histories shall be the seismic response spectrum specified in Clause 4.4.7. If site-specific time-histories are used, they shall include the site soil profile effects and be modified by the importance factor, I. Every step-by-step time-history method of analysis used for elastic or inelastic analysis shall satisfy the requirements of Clause 5.11. If an inelastic time-history method of analysis is used, the R-factors shall be taken as 1.0. The sensitivity of the numerical solution to the size of the time step used for the analysis shall be determined. A sensitivity study shall also be carried out to investigate the effects of variations in assumed material hysteretic properties.

4.5.3.5 Static pushover analysis The static pushover analysis shall be a step-by-step force deformation response analysis that takes account of inelastic response and the structural detailing specified in the design, e.g., anchorage of reinforcement for reinforced concrete members and connection details for steel members. Possible local and global instability and brittle failure modes shall be considered. The analysis results may be used to determine the deformation capacity of the structure.

4.6 Foundations 4.6.1 General In addition to satisfying the requirements of Section 6, the requirements specified in Clauses 4.6.2 to 4.6.6 shall also be satisfied in Seismic Performance Zones 2, 3, and 4.

4.6.2 Liquefaction of foundation soils An evaluation shall be made of the potential for liquefaction of foundation soils and the impact of liquefaction on bridge foundations.

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If liquefiable soils are identified and pose a hazard to the bridge, one or more of the following measures shall be taken: (a) use of an appropriate foundation type, e.g., deep piles or piers that extend below the zone of liquefiable soil. These foundation elements shall be designed to withstand ground-movementinduced soil loads; (b) soil improvement methods such as densification, removal and replacement, grouting, and dewatering or providing drainage so that the pore water pressure rise necessary to trigger liquefaction is controlled; and (c) design of bridge structures to withstand the predicted ground movements.

4.6.3 Stability of slopes An analysis shall be carried out to assess the effect of seismic forces on the stability of soil and rock slopes adjacent to the bridge. If the analysis shows that slope instability is likely during or following an earthquake, the effect of this instability on the bridge foundations, particularly regarding slope movement, shall be evaluated. If the movements are unacceptable, slope-stabilizing measures shall be carried out to reduce such movements.

4.6.4 Seismic forces on abutments and retaining walls Seismically induced lateral soil pressures on the back of abutment and retaining walls shall be included in the design where applicable. These pressures may be calculated using the Mononobe-Okabe method.

4.6.5 Soil-structure interaction When deemed appropriate by the Regulatory Authority, the interaction of soil-structure foundation systems due to earthquake loading shall be evaluated.

4.6.6 Fill settlement and approach slabs Unless exempted by the Regulatory Authority, settlement or approach slabs providing structural support between approach fills and abutments shall be provided. These approach slabs shall be adequately tied to the abutments. Positive ties to the abutment shall be capable of resisting a design force, Fs , calculated as follows: Fs = (µ + A)Ws where µ

= coefficient of friction between the slab and the underlying soil

A

= zonal acceleration ratio (from Table 4.1)

Ws

= permanent vertical reaction between slab and soil

This connection shall be free to rotate so that moment will not be transferred to the abutment backwall when the approach fill settles.

4.7 Concrete structures 4.7.1 General Concrete structures shall satisfy the requirements of Clauses to 4.7.2 to 4.7.5 and the applicable requirements of Section 8.

4.7.2 Seismic Performance Zone 1 Bridges in Seismic Performance Zone 1 shall satisfy the requirements of Clause 4.4.10.2.

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4.7.3 Seismic Performance Zone 2 Bridges in Seismic Performance Zone 2 shall satisfy the requirements of Clause 4.4.10.3. The transverse reinforcement at the top and bottom of a column shall be as specified in Clauses 4.7.4.2.5 and 4.7.4.2.6.

4.7.4 Seismic Performance Zones 3 and 4 4.7.4.1 General Bridges in Seismic Performance Zones 3 and 4 shall satisfy the requirements of Clauses 4.4.10.4 and 4.7.4.2 to 4.7.4.4.

4.7.4.2 Column requirements 4.7.4.2.1 General For the purposes of Clauses 4.7.4.2.2 to 4.7.4.2.7, a vertical support shall be considered to be a column if the ratio of the clear height to the maximum plan dimension of the support is equal to or greater than 2.5. For a flared column, the maximum plan dimension shall be taken at the minimum section of the flare. For supports with a ratio of clear height to maximum plan dimension of less than 2.5, the requirements of Clause 4.7.4.3 shall apply.

4.7.4.2.2 Longitudinal reinforcement The area of longitudinal reinforcement shall not be less than 0.008 or more than 0.06 times the gross cross-sectional area, Ag , of the column. The centre-to-centre spacing of longitudinal bars shall not exceed 200 mm.

4.7.4.2.3 Flexural resistance The biaxial resistance of columns shall not be less than that required to resist the forces specified in Clause 4.4.10.4.

4.7.4.2.4 Column shear and transverse reinforcement The factored shear force, Vf , on each principal axis of each column and concrete pile bent shall be as specified in Clause 4.4.10.4.3. The amount of transverse reinforcement shall not be less than that determined in accordance with Clause 8.9.3. The following requirements shall apply to the plastic hinge regions at the top and bottom of the column and pile bents: (a) In the plastic hinge regions, when the minimum factored axial compression force exceeds 0.10fc’Ag , Vc shall be as specified in Clause 8.9.3. Vc shall be taken as zero when the minimum factored axial compression force is zero. For values of minimum factored axial compression force between zero and 0.1fc’ Ag , linear interpolation may be used to determine the value of Vc . (b) The plastic hinge region shall be assumed to extend from the soffit of girders or cap beams at the top of columns to the top of foundations at the bottom of columns. This distance shall be taken as the greatest of (i) the maximum cross-sectional dimension of the column; (ii) one-sixth of the clear height of the column; or (iii) 450 mm. The plastic hinge region at the top of the concrete pile bent shall be taken as that specified for columns. At the bottom of the pile bent, the plastic hinge region shall be considered to extend from three times the maximum cross-section dimension below the calculated point of maximum moment, taking into account soil-pile interaction, to a distance of not less than the maximum cross-section dimension, but not less than 500 mm above the ground line.

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4.7.4.2.5 Transverse reinforcement for confinement at plastic hinge regions The cores of columns and concrete pile bents shall be confined by transverse reinforcement in the expected plastic hinge regions. The transverse reinforcement for confinement shall have a yield strength not more than that of the longitudinal reinforcement and the spacing shall be in accordance with Clause 4.7.4.2.6. For a circular column, the ratio of spiral reinforcement,  s , shall not be less than the greater of that determined in accordance with Clause 8.14.4.2 or

rs = 0.12

fc′ ⎡ 1.25Pf ⎤ ⎢0.5 + ⎥ fc fc′Ag ⎥⎦ fy ⎢⎣

where

⎡ 1.25Pf ⎢0.5 + fc fc′Ag ⎢⎣

⎤ ⎥ ≥ 1.0 ⎥⎦

Within plastic hinge regions, splices in spiral reinforcement shall be in accordance with Clause 8.14.4.2. Lap splices in longitudinal reinforcement shall be used only as specified in Clause 4.7.4.2.7. For rectangular columns, the total cross-sectional area, Ash , of transverse reinforcement shall not be less than the greater of

Ash = 0.30shc

⎤ fc′ ⎡ Ag − 1⎥ ⎢ fy ⎣ Ac ⎦

Ash = 0.12shc

fc′ ⎡ 1.25Pf ⎢0.5 + fc fc′Ag fy ⎢⎣

⎤ ⎥ ⎥⎦

where

⎡ 1.25Pf ⎢0.5 + fc fc′Ag ⎢⎣

⎤ ⎥ ≥ 1.0 ⎥⎦

and s is the vertical spacing of transverse reinforcement. Ash shall be calculated for both principal axes of a rectangular column and the larger value shall be used. Transverse reinforcement in plastic hinge regions shall be provided by single or overlapping hoops or spirals. Seismic cross-ties having the same bar size as the tie may be used. Each end of the seismic cross-tie shall engage a peripheral longitudinal reinforcing bar. Seismic cross-ties shall be alternated so that hooks that do not qualify as seismic hooks are not adjacent to each other in the horizontal and vertical directions.

4.7.4.2.6 Spacing of transverse reinforcement for confinement Transverse reinforcement for confinement shall be provided in the plastic hinge regions specified in Clause 4.7.4.2.4 and shall extend into the top and bottom connections in accordance with Clause 4.7.4.4. The centre-to-centre spacing shall not exceed the smallest of 0.25 times the minimum component dimension, six times the diameter of the longitudinal reinforcement, or 150 mm. The centre-to-centre spacing of interlocking spirals or hoop cages in oblong columns shall not be greater than 0.75 times the diameter of the spiral or hoop cage. A minimum of four vertical bars shall be located within each overlapping region of the spirals or hoops.

4.7.4.2.7 Splices Splices shall satisfy the requirements of this Clause and Clause 8.15.9. May 2010 (Replaces p. 137, November 2006)

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Lap splices in longitudinal reinforcement shall not be located in plastic hinge regions and shall be permitted only within the centre half of column height unless the splices are located in a region where it is demonstrated that plastic hinging will not occur. The splice length shall not be less than the greater of 60 bar diameters or 400 mm. The centre-to-centre spacing of the transverse reinforcement over the length of the splice shall not exceed the smaller of 0.25 times the minimum cross-section dimensions of the component or 100 mm. Welded splices in accordance with Clause 8.15.9.2 or mechanical connection splices in accordance with Clause 8.4.4.4 may be used if not more than alternate bars in each layer of longitudinal reinforcement are spliced at a section and the distance between splices of adjacent bars is greater than the larger of 600 mm or 40db measured along the longitudinal axis of the column. 

4.7.4.3 Wall-type piers The requirements of this Clause shall apply to the design for the strong direction of a wall-type pier. The weak direction may be designed as a column in accordance with Clause 4.7.4.2. If the wall-type pier is not designed as a column in its weak direction, the limitations for shear resistance specified in this Clause shall apply. The reinforcement ratio, both horizontally,  h , and vertically,  v , in any wall-type pier shall not be less than 0.0025, and  v shall not be less than  h . Reinforcement spacing, both horizontally and vertically, shall not exceed 450 mm. The reinforcement required for shear shall be continuous and shall be distributed uniformly. The shear resistance, Vr , of the pier shall be taken as the lesser of 2.25c fcr bd and (0.41 c fcr +  h s fy)bd. Horizontal and vertical reinforcement shall be provided at each face of a pier. Splices in horizontal reinforcement shall be staggered and splices in horizontal and vertical layers shall not occur at the same location. Ties for end wall reinforcement need not extend across the strong direction.

4.7.4.4 Column connections The design forces for column connections shall be those for capacity-protected elements in accordance with Clause 4.4.10.4.2. The development length for all longitudinal steel shall be 1.25 times that specified in Clause 8.15.2. Column transverse reinforcement, as specified in Clause 4.7.4.2.5, shall be continued for a distance not less than the greater of 0.5 times the maximum column dimension or 400 mm from the face of the column connection into the adjoining component. The shear resistance provided by the concrete in the joint of a frame or bent, in the direction under consideration, shall not exceed 2.5c fcr bd.

4.7.5 Piles 4.7.5.1 General Pile reinforcing details shall meet the requirements of Clauses 4.7.5.2 to 4.7.5.4 and 8.23.

4.7.5.2 Seismic Performance Zone 1 No additional design provisions need to be considered for Seismic Performance Zone 1.

4.7.5.3 Seismic Performance Zone 2 4.7.5.3.1 General Piles for structures in Seismic Performance Zone 2 shall meet the requirements of Clause 4.4.10.3. Concrete piles shall be anchored to the pile footing or cap by embedment of pile reinforcement or by anchorages to develop uplift forces. The embedment length shall not be less than 1.25 times the development length required for the reinforcement specified in Clause 8.15. Concrete-filled pipe piles shall be anchored by at least four dowels with a minimum steel ratio of 0.01. Dowels shall be embedded in the manner normally used for concrete piles.

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4.7.5.3.2 Cast-in-place concrete piles Longitudinal reinforcement shall be provided for cast-in-place concrete piles in the upper end of the pile for a length not less than the greater of one-third of the pile length or 2500 mm, with a minimum steel ratio of 0.005 provided by at least four bars. Spiral reinforcement or equivalent ties of not less than 10M bars shall be provided at a pitch not exceeding 225 mm, except that the pitch shall not exceed 75 mm within a length not less than the greater of 600 mm or 1.5 times the maximum cross-section dimension below the pile footing reinforcement or cap reinforcement.

4.7.5.3.3 Precast concrete piles Longitudinal reinforcement in precast concrete piles shall not be less than 0.01 times the cross-sectional area and shall consist of at least four bars or tendons. Spiral reinforcement or equivalent ties in precast concrete piles shall not be less than 10M bars at a pitch not exceeding 225 mm, except that the pitch shall not exceed 75 mm within a length not less than the greater of 600 mm or 1.5 times the maximum cross-section dimension below the pile footing reinforcement or cap reinforcement.

4.7.5.4 Seismic Performance Zones 3 and 4 4.7.5.4.1 General In addition to meeting the requirements specified in Clause 4.7.5.3, piles in Seismic Performance Zones 3 and 4 shall meet the requirements of Clauses 4.7.5.4.2 to 4.7.5.4.5.

4.7.5.4.2 Confinement length The upper end of every pile shall be reinforced as a potential plastic hinge region except when it can be established that there is no possibility of significant lateral deflection of the pile. The potential plastic hinge region shall extend from the underside of the pile footing or cap over a length that is the greater of twice the maximum cross-section dimension or 600 mm. Where a plastic hinge can form at a lower level, the confinement transverse reinforcement shall be provided to the lower level.

4.7.5.4.3 Confinement reinforcement The transverse reinforcement within the confinement length, as specified in Clause 4.7.5.4.2, shall be in accordance with the requirements for columns in Clause 4.7.4.2.5.

4.7.5.4.4 Cast-in-place concrete piles Longitudinal reinforcement shall be provided for cast-in-place concrete piles for the full length of the piles. In the upper two-thirds of the pile, the longitudinal steel ratio, provided by not fewer than four bars, shall not be less than 0.0075. Spiral reinforcement or equivalent ties of not less than 10M bars shall be provided at a pitch not exceeding 225 mm, except that the pitch shall not exceed 75 mm for the top portion of the pile over a distance not less than the greater of 1200 mm or twice the maximum cross-section dimension, and confinement reinforcement shall be in accordance with Clause 4.7.5.4.3.

4.7.5.4.5 Precast concrete piles The longitudinal reinforcement in precast concrete piles shall not be less than 1% of the cross-sectional area of the pile and shall consist of at least four bars or tendons. Spiral reinforcement or equivalent ties in precast concrete piles shall not be less than 10M bars at a pitch not exceeding 225 mm, except for the top 1200 mm, where the pitch shall not exceed 75 mm and the confinement reinforcement shall be in accordance with Clause 4.7.5.4.3.

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4.8 Steel structures 4.8.1 General Steel structures shall meet the requirements of Clause 4.8 as well as the applicable requirements of Section 10. Clause 4.8 shall not apply to structures that are designed to resist full elastic seismic loads. There shall be a continuous and clear load path or paths. Proper load transfer shall be considered in designing foundations, substructures, superstructures, and connections. Welds located in regions of expected inelastic deformations shall be complete penetration welds. Partial penetration groove welds shall not be permitted in these regions. Abrupt changes in cross-sections of members shall not be permitted in regions of expected inelastic deformation unless demonstrated to be acceptable by analysis and such acceptability is supported by research results.

4.8.2 Materials Ductile substructure elements shall be made of steels conforming to CSA G40.21, Grade 350A, 350AT, 300W, 350W, 300WT, or 350WT. Materials other than these may be used if Approved and the probable and nominal strengths are correctly established. Other elements shall be made of steels in accordance with Clause 10.4.1.

4.8.3 Sway stability effects The sway effects produced by the vertical loads acting on the structure in its displaced configuration shall be determined from a second-order analysis. Alternatively, the requirements of CAN/CSA-S16 may be applied.

4.8.4 Steel substructures 4.8.4.1 General Clauses 4.8.4.2 to 4.8.4.4 shall apply to single-tier steel substructures of single-level bridges. For other structures, the requirements of Clause 4.8.5 shall apply.

4.8.4.2 Seismic Performance Zone 1 Steel substructures in Seismic Performance Zone 1 shall meet the requirements of Clause 4.4.10.2.

4.8.4.3 Seismic Performance Zone 2 4.8.4.3.1 General Steel substructures in Seismic Performance Zone 2 shall meet the requirements of Clauses 4.8 and 4.4.10.3.

4.8.4.3.2 Ductile moment-resisting frames and bents 4.8.4.3.2.1 General Ductile moment-resisting frames and bents shall meet the requirements of Clause 4.8.4.4.2, as modified by Clauses 4.8.4.3.2.2 and 4.8.4.3.2.3.

4.8.4.3.2.2 Columns Columns shall be designed as ductile substructure elements. The maximum axial compressive load limit of Clause 4.8.4.4.2.2 shall be replaced by 0.60Ag Fy .

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4.8.4.3.2.3 Beams, panel zones, and connections Beams, panel zones, moment-resisting connections, and column base connections shall be designed as capacity-protected elements as specified in Clause 4.4.10.3.2. The nominal flexural resistance of the column shall be determined from Clause 4.8.4.4.2.3, with φ s taken as unity.

4.8.4.3.3 Ductile single-column structures Ductile single-column structures shall meet the requirements of Clause 4.8.4.4.2, except that the maximum axial compressive load limit of Clause 4.8.4.4.2.2 shall be replaced by 0.60Ag Fy .

4.8.4.3.4 Ductile concentrically braced frames Ductile concentrically braced frames and bents shall meet the requirements of Clause 4.8.4.4.3.

4.8.4.3.5 Concentrically braced frames and bents with nominal ductility Concentrically braced frames and bents with nominal ductility shall meet the requirements of Clause 4.8.4.4.4, except that braces in chevron-braced frames need not comply with Clause 4.8.4.4.3.3 but shall meet the requirements of Clause 4.8.4.4.4.3.

4.8.4.3.6 Other framing systems Other framing systems shall meet the requirements of Clause 4.8.4.4.5 or 4.8.5.

4.8.4.4 Seismic Performance Zones 3 and 4 4.8.4.4.1 General Steel substructures in Seismic Performance Zones 3 and 4 shall meet the requirements of Clause 4.8 and the applicable requirements of Clause 4.4.10.4.

4.8.4.4.2 Ductile moment-resisting frames and single-column structures 4.8.4.4.2.1 General Clause 4.8.4.4.2 shall apply to ductile moment-resisting frames and bents constructed with I-shape beams and columns connected with their webs in a common plane. Columns shall be designed as ductile structural elements. The beams, the panel zone at column-beam intersections, and the connections shall be designed as capacity-protected elements in accordance with Clause 4.4.10.4.2. Moment-resisting frames that do not meet these requirements shall be designed in accordance with the requirements for ductile moment-resisting frames of Clause 27 of CAN/CSA-S16.1 using R = 5, or in accordance with Clause 4.8.5.

4.8.4.4.2.2 Columns Columns shall be Class 1 sections in accordance with Section 10. Welded sections shall have web-to-flange welds proportioned to develop the full tensile capacity of the web. The resistance of columns to combined axial load and bending shall be determined in accordance with Clauses 10.8.3 and 10.9.4. The factored axial compression due to the combination of seismic load and permanent loads shall not exceed 0.30Ag Fy . The factored shear resistance, Vr , developed by the column web shall be taken as 0.55φ s wdFy . The potential plastic hinge locations near the top and base of each column shall be laterally supported and the unsupported distance from these locations shall not exceed 980ry / Fy . These lateral supports shall be provided either directly to the flanges or indirectly through a column web stiffener or a continuity plate. Each column flange lateral support shall resist a force of not less than 2% of the nominal column flange strength (bbf t Fy ) at the support location. The possibility of complete load reversal shall be considered. November 2006

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Splices that incorporate partial joint penetration groove welds shall be located away from the potential plastic hinge locations at a minimum distance equal to the greatest of (a) one-fourth the clear height of column; (b) twice the column depth; and (c) 1 m. Fasteners connecting the separate elements of built-up columns shall have resistances able to support full yielding at potential plastic hinge locations.

4.8.4.4.2.3 Beams The factored resistances of the beams shall be determined in accordance with Clause 10.10 or 10.11. At a joint between beams and columns, the sum of the factored resistances of the beams shall not be less than the sum of the probable resistances of the column(s) framing into the joint. The probable resistance of column(s) shall be taken as 1.25 times their nominal flexural capacity, determined as follows unless demonstrated otherwise by rational analysis:

⎡ C ⎤ 1.18Mpx ⎢1− f ⎥ ≤ Mpx ⎢⎣ AgFy ⎥⎦

4.8.4.4.2.4 Seismic design forces for panel zones and connections Column-beam intersection panel zones, moment-resisting connections, and column base connections shall be designed as capacity-protected elements in accordance with Clause 4.4.10.4.2.

4.8.4.4.2.5 Additional requirements for panel zones and connections Panel zones shall be designed in such a manner that the vertical shearing resistance is determined in accordance with Clause 10.10.5, using Ft = 0. Diagonal stiffeners may be used. Beam-to-column connections shall have resistances not less than the resistances of the beam specified in Clause 4.8.4.4.2.3. Beam flange continuity plates shall be proportioned to meet the stiffener requirements of Clause 10.18.5.3 and shall be connected to both column flanges and the web. They shall be provided on both sides of the panel zone web, finish with a total width at least 0.8 times the flange width of the opposing flanges, and meet the b/t limit of a Class 3 projecting element specified in Clause 10.9.2. Flanges and connection plates in bolted connections shall have a factored net section ultimate resistance in accordance with Item (b) or (c) of Clause 10.8.2 at least equal to the factored gross area yield resistance specified in Clause 10.8.2(a).

4.8.4.4.3 Ductile concentrically braced frames 4.8.4.4.3.1 General Braces are the ductile substructure elements in ductile concentrically braced frames. The modified design forces for these members shall be determined in accordance with Clause 4.4.10.4.2.

4.8.4.4.3.2 Bracing systems Diagonal braces shall be oriented in such a manner that in any planar frame at least 30% of the horizontal shear carried by the bracing system is carried by tension braces and at least 30% is carried by compression braces. Frames in which seismic load resistance is provided by any of the following shall not be considered ductile concentrically braced frames: (a) chevron bracing or V-bracing, in which pairs of braces are located either above or below a beam and meet the beam at a single point within the middle half of the span; (b) K-bracing, in which pairs of braces meet a column on one side near its mid-height; and (c) knee bracing.

4.8.4.4.3.3 Bracing members

Bracing members shall have a slenderness ratio, L/r, less than 1900/ Fy .

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In built-up bracing members, the slenderness ratio of the individual parts shall be not greater than 0.5 times the slenderness ratio of the member as a whole. Symmetrical open sections shall be Class 1 in accordance with Section 10. Width-thickness ratios shall not exceed 145/ Fy (330/ Fy for rectangular and square hollow structural sections and 13 000/Fy for circular hollow structural sections). The factored compressive resistance of a brace shall be determined as the product of Cr specified in Clause 10.9.3 and a reduction factor equal to (1 + 0.35λ). This factor need not be applied if the tension braces acting in the same plane as the compression brace have sufficient reserve capacity to compensate for the reduction.

4.8.4.4.3.4 Brace connections Brace connections shall be designed as capacity-protected elements in accordance with Clause 4.4.10.4.2. The controlling probable resistance shall be taken as the axial tensile yield strength of the brace, Ag Fy . Eccentricities in brace connections shall be minimized. Brace connections, including gusset plates, shall be detailed to avoid brittle failures due to rotation of the brace when it buckles. This ductile rotational behaviour shall be allowed for, either in the plane of the frame or out of it, depending on the slenderness ratios. Fasteners that connect the separate elements of built-up bracing members shall, if the overall buckling mode induces shear in the fastener, have resistances able to support one-half of the yield load of the smaller component being joined, with this force assumed to act at the centroid of the smaller member.

4.8.4.4.3.5 Columns, beams, and other connections Columns, beams, beam-to-column connections, and column splices that participate in the lateral-load-resisting system shall be designed as capacity-protected elements in accordance with Clauses 4.4.10.4.2 and 4.8.4.4.3.4 and shall also meet the following requirements: (a) Columns, beams, and connections shall resist forces arising from load redistribution following brace buckling or yielding. The brace compressive resistance shall include the reduction factor specified in Clause 4.8.4.4.3.3 if this creates a more critical condition. (b) Column splices made with partial penetration groove welds and subject to net tension forces due to overturning effects shall have factored resistances not less than 50% of the flange yield load of the smaller segment.

4.8.4.4.4 Concentrically braced frames with nominal ductility 4.8.4.4.4.1 General Braces are the ductile substructure elements in nominally ductile concentrically braced frames. The modified design forces for these members shall be determined in accordance with Clause 4.4.10.4.2.

4.8.4.4.4.2 Bracing systems Bracing systems considered to have nominal ductility include tension diagonal bracing, chevron or V-bracing, and direct tension-compression diagonal bracing. K-braced frames, in which pairs of braces meet a column near its mid-height, and knee-braced frames shall not be considered concentrically braced frames with nominal ductility.

4.8.4.4.4.3 Bracing members Inclined compression bracing members shall be Class 2 sections as specified in Section 10 or shall have cross-section elements that can undergo limited straining while sustaining the yield stress.

4.8.4.4.4.4 Brace connections Brace connections shall be designed as capacity-protected elements in accordance with Clause 4.4.10.4.2. The controlling probable resistance shall be taken as the axial tensile yield strength of the brace, Ag Fy . For tension-only bracing, the load selected shall be multiplied by an additional factor of 1.10.

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4.8.4.4.4.5 Columns, beams, and connections Columns, beams, and connections shall be designed as capacity-protected elements in accordance with Clauses 4.4.10.4.2 and 4.8.4.4.3.5.

4.8.4.4.4.6 Chevron-braced and V-braced systems Braces in chevron-braced frames shall meet the requirements of Clause 4.8.4.4.3.3. The beam attached to chevron braces or V-braces shall be continuous between columns and its top and bottom flanges shall be designed to resist a lateral load of 1.5% of the flange yield force at the point of intersection with the braces. The beam shall (a) resist the combined effect corresponding to one brace attaining its reduced compressive resistance, as specified in Clause 4.8.4.4.3.3, with the other brace attaining its tensile capacity, Ag Fy , and the permanent loads acting on the beam; or (b) be a Class 1 section, as specified in Section 10, and the beam connections at the columns shall resist the load effects corresponding to plastic hinging at the brace intersection point. When such a beam is supported from below by chevron braces, it shall have adequate nominal resistance to support its permanent loads without the support provided by the braces.

4.8.4.4.5 Ductile eccentrically braced frames Ductile eccentrically braced frames may be proportioned in accordance with Clause 27.7 of CAN/CSA-S16, using R = 5.

4.8.5 Other systems Other framing systems and frames that incorporate special bracing, base isolation, or other energy-absorbing devices, or special ductile superstructure elements, shall be designed on the basis of published research results, observed performance in past earthquakes, or special investigation, and shall require Approval.

4.9 Joints and bearings 4.9.1 General The requirements of Section 11 shall apply to joints and bearings.

4.9.2 Seismic design forces The seismic design forces shall be in accordance with Clause 4.4.10.

4.10 Seismic base isolation 4.10.1 General Clause 4.10 specifies requirements for isolator units and for the seismic isolation design of highway bridges. Design requirements for isolation bearings are specified in Clauses 4.10.2 to 4.10.10. These requirements provide a revised design procedure for isolation bearings that allows for the possibility of large displacements resulting from the seismic response. General test requirements are specified in Clause 4.10.11. Requirements for elastomeric isolators are specified in Clauses 4.10.12 and 4.10.13. Additional requirements for sliding isolators are specified in Clauses 4.10.14 and 4.10.15. The requirements of Section 11 shall also apply. Isolation systems without self-centring capabilities shall not be used.

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4.10.2 Zonal acceleration ratio The zonal acceleration ratio, A, shall be as specified in Table 4.1 but not less than 0.1. Note: The zonal acceleration ratio specified in Table 4.1 for seismic isolation design is the same as that for conventional design.

4.10.3 Seismic performance zones The seismic performance zones, which delineate the method of analysis and the minimum design requirement, are the same as those for conventional design and are specified in Table 4.1.

4.10.4 Site effects and site coefficient The site coefficient for seismic isolation design, Si , which accounts for the site condition effects on the elastic response coefficient, shall be as specified in Table 4.7.

Table 4.7 Site coefficient for seismic isolation design, Si (See Clauses 4.10.4 and 4.10.6.2.1.) Soil profile type (see Clauses 4.4.6.2 to 4.4.6.5)

Site coefficient for seismic isolation design, Si

I

1.0

II

1.5

III

2.0

IV

2.7*

*Site-specific studies should be used for isolated bridges on Type IV soils.

4.10.5 Response modification factors and design requirements for substructure Response modification factors, R, for all substructures shall be limited to 1.5, whereas substructures for lifeline and emergency-route bridges shall be designed to remain elastic (R = 1.0). For all isolated bridges, the design and detailing requirements for substructures in Seismic Performance Zones 2, 3, and 4 shall, at a minimum, be equivalent to the requirements for structures in Seismic Performance Zone 2.

4.10.6 Analysis procedures 4.10.6.1 General Table 4.2 shall be used to determine the applicable analysis procedure. The application of the applicable analysis procedure to isolated bridges shall be as specified in Clause 4.10.6.2 or 4.10.6.3. However, for isolation systems where the effective damping (expressed as a percentage of critical damping) exceeds 30%, a three-dimensional non-linear time-history analysis shall be performed using the hysteresis curves of the isolation system unless the value of B in Clause 4.10.6.2.1 is limited to 1.7.

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4.10.6.2 Uniform-load/single-mode spectral analysis Note: See Clauses 4.5.3.1 and 4.5.3.2 for the uniform-load and single-mode spectral methods.

4.10.6.2.1 Statically equivalent seismic force and coefficient Except for the case where a soil profile for the bridge site is Type IV, the statically equivalent seismic force, F, shall be F = C’smW where C’sm

= elastic seismic response coefficient for isolated structures =

W

ASi A ≤ 2 .5 BTe B

= dead load of the superstructure segment supported by isolation bearings

The displacement, di , across the isolation bearings (in millimetres) shall be di = 250ASiTe B where A

= zonal acceleration ratio from Table 4.1

B

= damping coefficient from Table 4.8 for the direction under consideration

Si

= dimensionless site coefficient for isolation design for the given soil profile, as specified in Table 4.7

Te

= period of vibration, s =

2p

W S keff g

where

Σ k eff = sum of the effective linear stiffnesses of all bearings and substructures supporting the superstructure segment, calculated at displacement di

g

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Table 4.8 Damping coefficient, B (See Clauses 4.10.6.2.1 and 4.10.11.2.) Equivalent viscous damping, β (% of critical)

Damping coefficient, B

≤2

0.8

5

1

10

1.2

20

1.5

30

1.7

40

1.9

50

2

Note: The percentage of critical damping shall be verified by a test of the isolation system’s characteristics as specified in Clause 4.10.11.3.3. The damping coefficient shall be based on linear interpolation for damping levels other than those specified in this Table. For isolation systems where the effective damping exceeds 30% of critical, a three-dimensional non-linear time-history analysis shall be performed using the hysteresis curves of the system, unless B is limited to 1.7.

4.10.6.2.2 Application of uniform-load/single-mode method of analysis The statically equivalent force determined in accordance with Clause 4.10.6.2.1, which is associated with the displacement across the isolation bearings, shall be applied using either the uniform-load method or the single-mode spectral method of analysis independently along two perpendicular axes and combined as specified in Clause 4.4.9.2. The effective linear stiffness of the isolators used in the analysis shall be calculated at the design displacement.

4.10.6.3 Multi-mode spectral analysis Note: See Clause 4.5.3.3 for the multi-mode spectral method.

Where the appropriate ground motion response spectrum for the isolated modes is specified by Clause 4.10.6.2.1, an equivalent linear response spectrum analysis shall be performed in accordance with Clause 4.5.3. The ground motion response spectrum specified in Clause 4.4.7 shall be used for all other modes of vibration. The effective linear stiffness of the isolators shall be calculated at the design displacements. The combination of orthogonal seismic forces shall be in accordance with Clause 4.4.9.2.

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4.10.6.4 Time-history analysis Note: See Clause 4.5.3.4 for the time-history method.

For isolation systems requiring a time-history analysis, the following requirements shall apply: (a) The isolation system shall be modelled using the non-linear deformational characteristics of the isolators determined and verified by test in accordance with Clause 4.10.11. (b) Pairs of horizontal ground motion time-history components shall be selected from different recorded events and modified to be compatible with the design spectra of Clause 4.4.7. The following methods may be used to achieve this modification: (i) time histories may be scaled so that their 5%-damped response spectra do not fall below the design spectra of Clause 4.4.7 by more than 10% in the period range of 1 to 5 s or by more than 20% in the range below 1 s; or (ii) time histories may be scaled so that the square root of the sum of the squares (SRSS) of the 5%-damped spectrum of the scaled components does not fall below 1.3 times the design spectra of Clause 4.4.7 for the period range of 1 to 5 s. (c) At least three appropriate pairs of time histories shall be developed and each pair shall be applied simultaneously to the model. The maximum response of the parameter of interest shall be used for the design.

4.10.7 Clearance and design displacements for seismic and other loads The design displacements in the two orthogonal directions for clearance purposes shall be the maximum displacement determined in each direction from the analysis. The required clearance for lifeline and emergency-route bridges shall be 1.25 times the maximum displacements calculated. The total design displacement for the testing requirements of Clause 4.10.11 shall be the maximum of 50% of the elastomer shear strain in an elastomeric-based system or the maximum displacement that results from the combination of loads specified in Clause 4.4.9.2. Horizontal deflections in the isolators resulting from load combinations involving wind loads on structure and traffic, braking forces, and centrifugal forces, as specified in Table 3.1, as well as thermal movements, shall be calculated and adequate clearance shall be provided.

4.10.8 Design forces for Seismic Performance Zone 1 The seismic design force of the connection between superstructure and substructure at each isolator for bridges in Seismic Performance Zone 1, FA , shall be FA = keff di where keff = di

effective linear stiffness of the isolation bearing calculated at displacement di = displacement of the isolated superstructure as specified in Clause 4.10.6.2.1, using a minimum zonal acceleration ratio, A, of 0.10

4.10.9 Design forces for Seismic Performance Zones 2, 3, and 4 The requirements of Clauses 4.4.10.3 and 4.4.10.4 and the response modification factor and design requirements of Clause 4.10.5 shall apply in Seismic Performance Zones 2, 3, and 4. The seismic design forces for columns and piers shall not be less than the forces resulting from the yield level of a softening system, the friction level of a sliding system, or the ultimate capacity of a sacrificial seismic-restraint system. In all cases, the larger of the static or dynamic conditions shall apply.

4.10.10 Other requirements 4.10.10.1 Non-seismic lateral forces Isolated structures shall resist all non-seismic lateral load combinations applied above the isolation system, including load combinations involving wind loads on the structure and the traffic, braking forces, and centrifugal forces specified in Table 3.1.

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An elastic restraint system shall be provided to limit lateral displacements of the isolation system caused by non-seismic forces, to a value satisfactory to the design Engineer.

4.10.10.2 Lateral restoring force The isolation system shall be configured to produce a lateral restoring force such that the lateral force at the design displacement is at least 0.025W greater than the lateral force at 50% of the design displacement.

4.10.10.3 Vertical load stability The isolation system shall provide a factor of safety of at least 3.0 for vertical loads (dead load plus live load) in its laterally undeformed state. It shall also be designed to be stable under the dead load plus or minus any vertical load resulting from seismic effects at a horizontal displacement of 1.5 times the total design displacement for isolation systems with a lateral restoring force. If the design is based on maximum credible response spectra, the 1.5 and 3.0 coefficients shall be reduced to 1.1 and 2.2, respectively.

4.10.10.4 Cold weather requirements Cold weather performance shall be considered in the design of all types of isolation systems in sustained low-temperature zones.

4.10.11 Required tests of isolation system 4.10.11.1 General The deformation characteristics and damping values of the isolation system used in the design and analysis shall be based on the tests specified in Clause 4.10.11. Tests on similarly sized isolators may be used to satisfy the requirements of Clause 4.10.11. Such tests shall validate design properties that can be extrapolated to the actual sizes used in the design. The design shall also be based on manufacturers’ pre-Approved or certified test data.

4.10.11.2 Prototype tests The following requirements shall apply to prototype tests: (a) Prototype tests shall be performed on two full-size specimens of each type and size similar to that used in the design. The tests specimens shall include the elastic restraint system, if such a system is used in the design. The specimens tested shall not be used for construction. (b) For each cycle of tests, the force-deflection and hysteretic behaviour of the test specimens shall be recorded. (c) The following sequence of tests shall be performed for the prescribed number of cycles at a vertical load similar to the typical or average dead load on the isolators of a common type and size. The total design displacement of these tests shall be in accordance with Clause 4.10.7: (i) 20 fully reversed cycles of loading at a lateral force corresponding to the maximum non-seismic design force; (ii) three fully reversed cycles of loading at each of the following increments of the total design displacement: 0.25, 0.50, 0.75, 1.0, and 1.25; and (iii) 15 Si /B cycles, but not fewer than 10 fully reversed cycles of loading at 1.0 times the total design displacement and a vertical load similar to dead load. B shall be determined from Table 4.8. (d) The vertical load-carrying elements of the isolation system shall be statically tested at the displacements resulting from the requirements of Clause 4.10.10.3. In these tests, the maximum downward force shall be taken as the load of 1.25D plus the increased vertical load due to earthquake effects, and the minimum download force shall be taken as 0.8D minus the vertical load due to earthquake effects, where EQ is any vertical load resulting from horizontal seismic loads. (e) If a sacrificial elastic restraint system is used, the ultimate capacity shall be established by test.

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4.10.11.3 Determination of force-deflection characteristics 4.10.11.3.1 General The following requirements shall apply: (a) The force-deflection characteristics of the isolation system shall be based on the cyclic load test results for each fully reversed cycle of loading. (b) The effective stiffness of an isolator unit, keff , shall be calculated for each cycle of loading as follows: Fp − Fn keff = Dp − Dn where Fp and Fn are the maximum positive and maximum negative forces, respectively, and Δp and Δn are the maximum positive and maximum negative test displacements, respectively. If the minimum effective stiffness is to be determined, Fp,min and Fn,min shall be used in the equation.

4.10.11.3.2 System adequacy The performance of the test specimens shall be deemed to be adequate if the following conditions are satisfied: (a) The force-deflection plots of all tests specified in Clause 4.10.11.2 have a positive incremental force-carrying capacity. (b) For each increment of test displacement specified in Clause 4.10.11.2(c)(ii), the following conditions are met: (i) there is less than a ± 10% change from the average effective stiffness of a given test specimen over the required three cycles of test; and (ii) there is not more than a 10% difference in the average values of effective stiffness of the two test specimens of a common type and size of the isolator unit over the required three cycles of test. (c) There is not more than a 20% increase or 20% decrease in the effective stiffness between the first cycle and any subsequent cycle of each test specimen for the cyclic tests specified in Clause 4.10.11.2(c)(iii). (d) There is not more than a 20% decrease in the effective damping of each test specimen for the cyclic tests specified in Clause 4.10.11.2(c)(iii). (e) All specimens of vertical load-carrying elements of the isolation system remain stable at the displacements specified in Clause 4.10.10.3 for the static loads specified in Clause 4.10.11.2(d).

4.10.11.3.3 Design properties of the isolation system The following requirements shall apply to the design properties of the isolation system: (a) The minimum and maximum effective stiffness of the isolation system shall be determined as follows: (i) The value of kmin shall be based on the minimum effective stiffnesses of individual isolator units as determined by the cyclic tests of Clause 4.10.11.2(c)(ii) at a displacement amplitude equal to the design displacement. (ii) The value of kmax shall be based on the maximum effective stiffnesses of individual isolator units as determined by the cyclic tests of Clause 4.10.11.2(c)(ii) at a displacement amplitude equal to the design displacement. (b) The equivalent viscous damping ratio, β , of the isolation system shall be calculated as follows:

b=

1 Total area • 2π Skmax di2

where the total area represents the energy absorbed by the isolation system in one cycle and shall be taken as the sum of the areas inside the hysteresis loops of all isolators. The hysteresis loop area of each isolator shall be taken as the minimum area of one cycle obtained from the three hysteresis loops established by the cyclic tests of Clause 4.10.11.2(c)(ii) at a displacement amplitude equal to the design displacement.

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4.10.12 Elastomeric bearings — Design 4.10.12.1 General Isolator units that use elastomeric bearings shall be designed in accordance with Clause 4.10.12. Additional test requirements are specified in Clause 4.10.13. The requirements of Clause 4.10.12 shall be considered supplemental to those of Section 11. The requirements of Clause 4.10.12 shall govern in the event of a conflict with those of Section 11. The design procedures specified in Clause 4.10.12 are based on service loads excluding impact. Elastomeric bearings used in isolation systems shall be reinforced using integrally bonded steel reinforcement. Fabric reinforcement shall not be permitted.

4.10.12.2 Shear strain components for isolation design The four components of shear strain in the bearing shall be calculated as follows: (a) Shear strain due to compression by vertical loads, ε sc , shall be calculated as follows:

ε sc = 6Sε c where S

= shape factor of the bearing, as defined in Clause 11.2

εc

= Δc /Σ ti where

Σ ti = sum of the thicknesses of the deformable rubber layers = Δc /T =

P Ar E (1+ 2kS 2 )

The effects of creep of the elastomer shall be added to the instantaneous compressive deflection, Δc , when long-term deflections are considered. They shall not be included when the requirements of Clause 4.10.12.4 are applied. Long-term deflections shall be calculated from information relevant to the elastomer compound used, if it is available. If it is not, the values specified in Clause 11.6.6 shall be used as a guide. (b) Shear strain due to imposed lateral displacement, ε sh , shall be calculated as follows:

ε sh = Δs /T where T

= Σ ti

(c) Shear strain due to earthquake-imposed displacement, ε eq , shall be calculated as follows:

ε eq = di /T where T

= Σ ti

(d) Shear strain due to rotation, εsr , shall be calculated as follows:

e sr =

B 2q 2tiT

where T

= Σ ti

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4.10.12.3 Limiting criteria for allowable vertical loads The allowable vertical load on an elastomeric isolation bearing shall be governed by limitations on the equivalent shear strain in the rubber due to different load combinations and to the stability requirements specified in Clauses 4.10.12.4 to 4.10.12.6.

4.10.12.4 Combinations of shear strains due to service loads The following two criteria shall be satisfied for service loads that include dead load plus live load, thermal effects, creep, shrinkage, and rotation: (a) ε sc + ε sh + ε sr ≤ 0.5ε u ; and (b) ε sc ≤ 0.33ε u . 0.5ε u shall not exceed 5.0.

4.10.12.5 Combinations of shear strains due to dead and seismic loads The following criterion shall be satisfied for seismic loads that include dead load and seismic load, seismic design displacements, and rotation:

ε sc + ε eq + ε sr ≤ 0.75ε u

4.10.12.6 Stability against overturning Elastomeric isolation bearings shall be shown either by test or analysis to be capable of resisting the vertical loads specified in Clause 4.10.11.2(d) at the seismic design displacements specified in Clause 4.10.7.

4.10.13 Elastomeric bearings — Construction 4.10.13.1 General Isolator units that use elastomeric bearings shall be constructed in accordance with Clause 4.10.13. The requirements of Clause 4.10.13 shall be considered supplemental to Section 11. The requirements of Clause 4.10.13 shall govern in the event of a conflict with those of Section 11. Elastomeric bearings used in isolation systems shall be reinforced using integrally bonded steel reinforcement. Fabric reinforcement shall not be permitted. Seismic isolation bearings shall meet the requirements of Clause 4.10.13.2 and Section 11.

4.10.13.2 Additional requirements for elastomeric isolation bearings 4.10.13.2.1 General In addition to the material and bearing tests required by Clauses 4.10.10 and 4.10.11, the tests specified in Clauses 4.10.13.2.2 and 4.10.13.2.3 shall be performed on elastomeric isolation bearings.

4.10.13.2.2 Compression A 12 h sustained proof load test on each bearing shall be performed. The compressive load for the test shall be 1.5 times the sum of the maximum dead load plus live load. If bulging suggests poor laminate bond, the bearing shall be rejected.

4.10.13.2.3 Combined compression and shear A minimum of 20% of the bearings shall be selected at random for testing in combined compression and shear. The bearings may be tested in pairs. The compressive load shall be the dead load and the bearings shall be subjected to five complete reversed cycles of loading to shear strains of ± 0.5. Test results shall be within ±10% of those values assumed in design. Bearings that test outside this range may be accepted only on Approval.

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4.10.14 Sliding bearings — Design Sliding bearings may be used for isolation systems if Approved. The Regulatory Authority shall specify appropriate materials and design parameters. The requirements of Clause 11.6 for PTFE bearing surfaces shall be satisfied.

4.10.15 Sliding bearings — Construction Isolator units that use sliding bearings shall be constructed in accordance with Section 11.

4.11 Seismic evaluation of existing bridges 4.11.1 General The seismic evaluation of existing bridges shall be conducted by Engineers knowledgeable in the field of earthquake engineering. The Owner or those having jurisdiction shall be responsible for the identification and prioritization of existing bridges that require seismic evaluation.

4.11.2 Bridge classification The Owner or those having jurisdiction shall classify bridges in accordance with Clause 4.4.2. For lifeline bridges, special studies shall be performed to evaluate their seismic performance. The earthquake level and procedure used for evaluating lifeline bridges shall be specified by the Owner or those having jurisdiction and shall, at a minimum, comply with the requirements of this Code. For emergency-route and other bridges, the requirements of Clause 4.11 shall apply.

4.11.3 Damage levels 4.11.3.1 Moderate damage Moderate damage is damage that does not cause collapse of a bridge and following which the bridge can be repaired to full strength without full closure; access to emergency vehicles is available almost immediately after the earthquake and limited access to normal traffic is available within a few days.

4.11.3.2 Significant damage Significant damage is damage that does not cause collapse of a bridge but can take several weeks or months to repair; limited access to emergency and light traffic is sometimes available after a few days, but full service is not available until repairs are completed.

4.11.4 Performance criteria Emergency-route bridges predicted to withstand the major earthquake with moderate or less damage shall be considered satisfactory. Other bridges predicted to withstand the major earthquake with significant or less damage shall be considered satisfactory.

4.11.5 Evaluation methods 4.11.5.1 Minimum analysis requirements for evaluation The minimum analysis requirements for evaluation shall be as specified in Table 4.9.

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Table 4.9 Minimum analysis requirements for evaluation (See Clause 4.11.5.1.) Multi-span bridges Seismic performance zone

Single-span bridges Emergency-route

1 2 3 4

None None LE LE

Legend: LE = MM = None = SM =

Emergency-route

Other

Other

Regular

Irregular

Regular

Irregular

None None None LE

None LE SM MM

None LE MM MM

None None LE SM

None None LE MM

limited seismic evaluation required (see Clause 4.11.5.2) multi-mode spectral method (see Clause 4.5.3.3) no seismic evaluation required single-mode spectral method (see Clause 4.5.3.2)

4.11.5.2 Limited evaluation Limited evaluation shall require the following: (a) Available seat width shall be checked for the minimum requirements specified in Clause 4.4.10.5 or longitudinal restrainers complying with Clause 4.4.10.6 shall be provided. (b) Bearings shall be checked for a force demand not less than 20% of the tributary dead load in the restrained directions. (c) The potential for soil-liquefaction-induced ground movements, slope instability, approach fill settlements, and increases in lateral earth pressure shall be considered.

4.11.6 Load factors and load combinations for seismic evaluation In lieu of specific provisions provided by the Regulatory Authority, seismic evaluation of existing bridges shall be based on the following load factors and load combination: 1.0D + 1.0EQ Seismic forces and displacements resulting from orthogonal loading shall be combined in accordance with Clause 4.4.9.2.

4.11.7 Minimum support length For bridges requiring detailed evaluation, available support lengths at expansion bearings shall be checked for the greater of the maximum displacement calculated in accordance with Clause 4.11.5 or the empirical seat width requirements specified in Clause 4.4.10.5. Alternatively, longitudinal restrainers complying with Clause 4.4.10.6 shall be provided.

4.11.8 Member capacities 4.11.8.1 General For the purposes of Clause 4.11 only, member capacities, C, shall be the unfactored nominal resistance of the member.

4.11.8.2 Material strengths Material strengths shall be evaluated in accordance with Clause 14.7.

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4.11.8.3 Nominal resistance For existing structural members meeting all of the design and detailing requirements of this Code, the nominal resistance shall be calculated in accordance with Clauses 4.7 and 4.8. For members not meeting all of the design and detailing requirements of this Code, account shall be taken of the effects of any differences. Differences to be accounted for shall include, but not be limited to, the following: (a) For steel members, the influence of the width/thickness (b/t) ratios for local buckling shall be considered in evaluating their nominal resistance. (b) Steel members whose slenderness ratios exceed those allowed by this Code shall be considered to act in tension only unless their behaviour under compression is evaluated based on verified research results. (c) For reinforced concrete members with inadequately anchored or spliced steel bars, premature bond failure shall be considered in evaluating their nominal flexural resistance based on verified research results. (d) For reinforced concrete members, the concrete contribution to the shear resistance shall be reduced as the ductility demand increases in the structural member being evaluated. (e) Inadequately detailed beam-column joints and column-footing joints shall be checked for shear capacity.

4.11.8.4 Effects of deterioration The nominal resistances of existing members shall be reduced to account for any member defects or deterioration in accordance with Clause 14.14.3.

4.11.9 Required response modification factor For each structural element and connector, the required response modification factor, Rreq , shall be found such that the following equation is satisfied: Rreq = Se /C where Se

= seismic force effect assuming all members remain elastic, calculated in accordance with Clause 4.11.5, except as limited by capacities of other members

C

= member reserve capacity after the effects of dead load have been considered, calculated in accordance with Clause 4.11.8

4.11.10 Response modification factor of existing substructure elements The response modification factor provided, Rprov , shall be the R-factor specified in Clause 4.4.8.1 when all members and joints satisfy the design and detailing requirements of Clauses 4.7 and 4.8. For members and joints not so detailed, Rprov shall be determined from (a) an assessment of the consequences of specific detailing, and with due consideration for all possible failure modes and the expected length of inelastic deformations on the overall performance of the bridge. The selected levels for acceptable response modification factors shall meet the performance requirements specified in Clause 4.11.4; and (b) results from reversed-cyclic loading tests of structural components constructed to simulate as-built details, which provide a means for evaluating the influence of important details and for determining a suitable Rprov .

4.11.11 Evaluation acceptance criteria The structural elements and connectors of an existing bridge shall be deemed acceptable for seismic evaluation if Rprov is greater than or equal to Rreq . If any element or connector does not meet this requirement, rehabilitation in accordance with Clause 4.12 shall be carried out unless it can be demonstrated by non-linear analysis that the consequences would not be detrimental to the performance of the bridge.

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4.11.12 Other evaluation procedures The lateral strength (pushover analysis) and time-history analysis methods may be used for seismic evaluation of existing bridges. Care shall be taken with the modelling of the structure, selection of the input time histories, and interpretation of the analysis results.

4.11.13 Bridge access The loss of access resulting from an abutment structural failure, adjacent slope failure, or approach fill settlement shall be evaluated for emergency route bridges located in Seismic Performance Zones 3 and 4.

4.11.14 Liquefaction of foundation soils The potential for liquefaction of the foundations soils shall be evaluated for the following bridges: (a) bridges located in Seismic Performance Zone 4; and (b) multi-span bridges classified as emergency-route bridges and located in Seismic Performance Zone 3. If subsoil liquefaction is likely and the foundation movements are unacceptable, mitigation measures shall be taken (see Clause 4.6).

4.11.15 Soil-structure interaction When deemed appropriate by the Regulatory Authority, the interaction of soil-structure foundation systems to earthquake loadings shall be evaluated.

4.12 Seismic rehabilitation 4.12.1 Performance criteria Seismic rehabilitations shall be designed so that a minimum level of safety is provided. This level shall be (a) comparable to that intended for new bridges; or (b) as prescribed by the Regulatory Authority.

4.12.2 Response modification factor for rehabilitation The response modification factor, R, for the rehabilitated ductile substructure element shall be determined in accordance with Clause 4.11.10 but shall not exceed the smaller of (a) the value of R from Table 4.5 corresponding to the type of substructure element; or (b) 5.0.

4.12.3 Seismic rehabilitation 4.12.3.1 In the design of the rehabilitation measures, the following design aspects shall be accounted for: (a) the fact that increased stiffness due to strengthening can attract higher seismic loads; (b) the influence of the rehabilitation measures on fatigue life; (c) the influence of the rehabilitation measures on alteration of load paths; (d) the fact that strengthening some members can result in larger force demands on other members (including superstructure members), connections, and foundations; (e) the need to design rehabilitation measures to prevent damage to inaccessible underground foundations; (f) restraint on thermal movement due to added restrainers; (g) the fact that improvement of foundation soils can induce movements or tilting of the substructure; (h) the need for proper planning of the sequence if rehabilitation is applied in stages; (i) the need (if applicable) for adequate maintenance and inspection of the rehabilitated structure at regular intervals; and (j) such other design aspects as are applicable to the rehabilitation measures.

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4.12.3.2 In the design of the rehabilitation measures, the following requirements shall apply: (a) column rehabilitation jackets shall terminate 100 mm from the top of the footing and the bottom of the cap beam; (b) if uplift occurs near the base of a structure, care shall be taken to ensure adequate guiding for this movement. Due consideration shall be given to other effects, e.g., loss of support and impact; (c) if base isolators are employed, care shall be taken in assessing the structural stability at other limit state combinations (e.g., wind); (d) the durability of the rehabilitation measures shall be assessed; and (e) a complete re-analysis of the rehabilitated structure in both the longitudinal and transverse directions shall be conducted to assess the performance of the rehabilitated structure.

4.12.4 Seismic rehabilitation techniques Seismic rehabilitation techniques that have been analytically and experimentally verified shall be used, subject to Approval. Note: Seismic rehabilitation techniques include the following: (a) isolation of ground motion from the structure by “base isolation” bearings or other means; (b) increasing the ductility of the system with or without strengthening; (c) introduction of energy-dissipating devices; (d) installation of restrainers, bumpers, or both between spans; (e) alteration of load paths; (f) increasing available support lengths both longitudinally and transversely; (g) making provision for inelastic hinging to occur; (h) strengthening; (i) improvement of liquefaction-prone foundation soils; and (j) stabilization of approach fills and adjacent slopes.

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Section 5 — Methods of analysis 5.1 5.2 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.4.8 5.4.9 5.4.10 5.4.11 5.4.12 5.4.13 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.5.6 5.5.7 5.5.8 5.6 5.6.1 5.6.2 5.7 5.7.1 5.7.2 5.8 5.8.1 5.8.2 5.8.3 5.9 5.9.1 5.9.2 5.9.3 5.10 5.10.1 5.10.2 5.10.3 5.11 5.11.1 5.11.2 5.11.3 5.11.4

Scope 161 Definitions 161 Abbreviations and symbols 164 Abbreviations 164 Symbols 164 General requirements 167 Application 167 Analysis for limit states 167 Modelling 167 Structural responses 167 Factors affecting structural responses 170 Deformations 170 Diaphragms and bracing systems 170 Analysis of deck slabs 171 Analysis for redistribution of force effects 171 Analysis for accumulation of force effects due to construction sequence 171 Analysis for effects of prestress 171 Analysis for thermal effects 171 Secondary stability effects 171 Requirements for specific bridge types 171 General 171 Voided slab — Limitation on size of voids 171 Deck-on-girder 172 Truss and arch 172 Rigid frame and integral abutment types 172 Transverse wood deck 172 Box girder 172 Single-spine bridges 173 Dead load 173 Simplified methods of analysis (beam analogy method) 173 Refined methods of analysis 174 Live load 174 Simplified methods of analysis 174 Refined methods of analysis 202 Idealization of structure and interpretation of results 203 General 203 Effective flange widths for bending 203 Idealization for analysis 207 Refined methods of analysis for short- and medium-span bridges 207 Selection of methods of analysis 207 Specific applications 207 Model analysis 207 Long-span bridges 210 General 210 Cable-stayed bridges 210 Suspension bridges 210 Dynamic analysis 210 General requirements of structural analysis 210 Elastic dynamic responses 211 Inelastic-dynamic responses 211 Analysis for collision loads 211

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Seismic analysis 211 Stability and magnification of force effects 212 General 212 Member stability analysis for magnification of member bending moments 212 Structural stability analysis for lateral sway 212 Structural stability analysis for assemblies of individual members 212A

Annexes A5.1 (normative) — Factors affecting structural response 213 A5.2 (informative) — Two-dimensional analysis 217

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Section 5 Methods of analysis 5.1 Scope This Section specifies analysis requirements for bridges, including but not limited to bridges of the following superstructure types: (a) slab; (b) voided slab; (c) deck-on-girder, including slab-on-girder, steel-grid-deck-on-girder, and wood-deck-on-girder; (d) shear-connected beam; (e) truss; (f) arch; (g) rigid frame and integral abutment; (h) bridges incorporating wood beams; (i) box girder — single cell; (j) box girder — multi-cell; (k) box girder — multi-spine; (l) cable stayed; and (m) suspension. Note: In this Section, these are referred to as Type A, Type B, etc.

5.2 Definitions The following definitions apply in this Section: Cantilever slab — that portion of a deck slab that lies outside the outermost girder or web or lies outside the outermost lines of support. Deck — an element of a bridge superstructure that carries and distributes wheel loads to the substructure. Degree-of-freedom — one of a number of translations or rotations that are required to define the movement of a node. Distortional stresses — stresses developed in a cross-section because of distortion in its own plane. Divergence — an aerodynamic instability in torsion that is analogous to column buckling and usually occurs at wind speeds beyond the range normally considered in the design. Effective width — a reduced width of a flange or deck that enables a member to be proportioned on the basis of uniform stress. External portion of a bridge — a part of the transverse cross-section of a bridge, as follows: (a) for a solid slab bridge, the outermost 2.00 m of the transverse cross-section on either side of the bridge; (b) for a voided slab bridge with rectangular or circular voids, that part of the transverse cross-section on either side of the bridge that is on the outer side of the vertical plane bisecting the outermost void; (c) for a slab-on-girder bridge, that part of the transverse cross-section on either side of the bridge that is on the outer side of the vertical plane midway between the outermost girder and the girder next to it; and (d) for a multi-cell or multi-spine box girder bridge, that part of the transverse cross-section on either side of the bridge that is on the outer side of the vertical plane that bisects the area of the outermost cell. November 2006

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Flexural rigidity — the bending stiffness of a beam, EI, or the bending stiffness per unit width or per unit length of an orthotropic plate, Dx or Dy , respectively. Floor beam — a transverse structural member that supports a deck or longitudinal stringers and spans between longitudinal girders, trusses, or arches. Floor system — that portion of a bridge superstructure that directly supports traffic, including, where present, the deck, floor beams, and stringers. Grid — a plane assembly of intersecting beams subject to loading perpendicular to the plane formed by the assembly and characterized by the fact that interaction between beams takes place only at their intersections. Idealization — representation of a structure or load for purposes of analysis or testing. In-plane forces — forces acting in the plane of an element, member, or system. Integral abutment bridge — a bridge in which there is no expansion joint between the bridge superstructure and its abutment(s) and structural continuity with the abutment(s) is preserved. Interface shear — shear between a deck and a supporting beam. Internal portion of a bridge — that part of the transverse cross-section of a bridge contained between the two external portions. Large-deflection theory — a theory that assumes that deflections caused by the application of loads alter the behaviour of a structure to the extent that they need to be considered in the analysis of the structure. Longitudinal direction — the direction of traffic flow. Longitudinal moment — moment in the longitudinal vertical plane about a transverse axis. Longitudinal torsion — torsion about a longitudinal axis. Longitudinal vertical shear — vertical shear in the longitudinal vertical plane associated with change of longitudinal moment. Mathematical model — a conceptual approximation to a structure for purposes of analysis. Modification factor — a factor applicable to highway live loads (see Clause 3.8.4.2). Moment of inertia — the second moment of area of the cross-section of a component with respect to a centroidal axis in the plane of the area, unless otherwise specified in this Section. Multi-cell bridge — a box girder bridge with three or more webs per box and in which the bottom flange is continuous in the transverse direction. Multi-spine bridge — a box girder bridge in which the bottom flange is discontinuous in the transverse direction, thus forming spines mutually connected only by the deck slab and transverse diaphragms (if present). Orthotropic deck — a deck made of steel plates stiffened with open or closed steel ribs welded to the undersides of the steel plates. Orthotropic plate — a plate with different flexural and torsional rigidities in orthogonal directions. Radius of curvature — the radius at any point on a longitudinal line joining the centroids of transverse cross-sections, when viewed in plan.

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Rigid frame bridge — a bridge in which the piers, abutments, or both are structurally continuous with the longitudinal components of the superstructure. Shallow superstructure bridge type — one of the bridge types in which in-plane distortions of the transverse cross-section are negligible, i.e., slab, slab-on-girder, voided slab, and shear-connected beam bridge types (but only, in the case of shear-connected beams, if the interconnections of adjacent beams provide continuity of transverse flexural rigidity across the cross-section). Shear-connected beams — longitudinal beams placed side by side, with connections between adjacent beams, e.g., shear keys, for transferring transverse vertical shear. Skew angle — the angle between the longitudinal centreline of a bridge and a line normal to the centreline of bearings. Skew span (for a bridge in which the plan-form is a parallelogram) — the length of the unsupported edge. Skew width (for a bridge in which the plan-form is a parallelogram) — the width of the deck parallel to the supported edge. Small-deflection theory — analysis based on the assumption that deflections caused by the application of loads do not have a significant effect on the accuracy of the analysis and can therefore be ignored in the calculation of force effects. Span — the length between the supports of a bridge, taken along the line of the main supporting members. Spine — a portion of a bridge cross-section that comprises a portion of the deck, two webs, and a lower flange and thereby constitutes a closed box. Stringers — longitudinal structural members spanning between floor beams. Transverse direction — the direction perpendicular to the longitudinal direction at any point on a bridge. Transverse moment — moment in the transverse vertical plane about a longitudinal axis. Transverse torsion — torsion about a transverse axis. Transverse vertical shear — vertical shear in the transverse vertical plane associated with change of transverse moment. Voided slab — a concrete slab with circular or rectangular voids described in Clause 5.5.2 and geometrical and structural configurations that make the effects of cell distortion negligible. Warping stresses — in-plane stresses that are developed in a cross-section and are due to restraint of the in-plane displacements associated with warping of the cross-section’s components. Width — the following distances: (a) for a bridge in which the unsupported edges are parallel, the perpendicular distance between the unsupported edges of the bridge; and (b) for a bridge in which the unsupported edges are not parallel, the distance between the unsupported edges along a line perpendicular to the centreline of the bridge at the point of consideration.

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5.3 Abbreviations and symbols 5.3.1 Abbreviations The following abbreviations apply in this Section: FLS — fatigue limit state SLS — seviceability limit state ULS — ultimate limit state

5.3.2 Symbols The following symbols apply in this Section: A

= factor for calculating cantilever moments in deck slabs (see Figure 5.2)

As

= total area of stiffeners in width B, as shown in Figure 5.6 for orthotropic steel decks

Ax

= equivalent area per unit width of the transverse section of a voided slab

Ay

= equivalent area per unit length of the longitudinal section of a voided slab

a

= length of the longer side of a rectangular section; distance between adjacent transverse bracing members; for orthotropic steel decks, the distance centre-to-centre of longitudinal ribs (see Table 5.11)

B

= width of a bridge; for orthotropic steel decks, the spacing of transverse or longitudinal beams, as shown in Figure 5.6

Be

= a reduced value of B

Bp

= for orthotropic steel decks, the length of the cantilever

b

= length of the shorter side of a rectangular section; one-half of the transverse span of a deck slab, as shown in Figure 5.5

be

= a reduced value of b

C

= transverse distance of the wheel load from the supported edge of a cantilever slab, m; modification factor for simplified analysis of skewed slab-on-girder bridges (see Table CA5.1.3 of CSA S6.1)

Ce

= correction factor used to adjust the F value for longitudinal moment to account for the vehicle edge distance

Cf

= correction factor used to adjust the F value for longitudinal moment and longitudinal vertical shear

DVE

= vehicle edge distance for slab-on-girder bridges, m, as shown in Figure 5.1

Dt

= distribution width for transverse moment in timber decks

Dx

= longitudinal flexural rigidity per unit width

Dxy

= longitudinal torsional rigidity per unit width

Dy

= transverse flexural rigidity per unit length

Dyx

= transverse torsional rigidity per unit length

D1

= coupling rigidity per unit width

D2

= coupling rigidity per unit length

DLA

= dynamic load allowance, as defined in Clause 3.2

ds

= for box girder cross-sections, the length of each side of thickness t

E

= modulus of elasticity; a distribution width for one line of wheels for steel grid decks spanning longitudinally

EL

= modulus of elasticity of wood in the direction L shown in Figure A5.2.2

ET

= modulus of elasticity of wood in the direction T shown in Figure A5.2.2

Ec

= modulus of elasticity of concrete

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Es

= modulus of elasticity of steel

e

= for orthotropic steel decks, the distance centre-to-centre between adjacent closed ribs

F

= when a bridge superstructure is analyzed in accordance with simplified methods, a width dimension that characterizes load distribution for a bridge, as specified in Clauses 5.7.1.2 to 5.7.1.5 and 5.7.1.6.2, m

Fm

= when a bridge superstructure is analyzed in accordance with simplified methods, an amplification factor to account for the transverse variation in maximum longitudinal moment intensity, as compared to the average longitudinal moment intensity

Fv

= when a bridge superstructure is analyzed in accordance with simplified methods, an amplification factor to account for the transverse variation in maximum longitudinal vertical shear intensity, as compared to the average longitudinal vertical shear intensity

G

= shear modulus

GLT

= shear modulus of wood with respect to axes L and T shown in Figure A5.2.2

Gc

= shear modulus of concrete

Gs

= shear modulus of steel

I

= moment of inertia of the cross-section of a beam

iL

= longitudinal moment of inertia per unit width

iT

= transverse moment of inertia per unit length

J

= torsional inertia of a beam

jL

= longitudinal torsional inertia per unit width

jT

= transverse torsional inertia per unit length

K

= torsional constant for a rectangular section

k

= constant used in calculating maximum transverse vertical shear intensity due to live load in shear-connected beam bridges (see Clause 5.7.1.8.1)

L

= for simply supported spans, the span; for continuous spans, the span specified in Clause A5.1.2

Ls

= stringer span

1, 2 = distances between points of inflection, as shown in Figure 5.6 for orthotropic steel decks



MT

= maximum longitudinal moment for one lane width of truck or lane loading, as applicable, including dynamic load allowance

Me

= moment at the end of an individual compression member

Mg

= for girder-type bridges, the maximum longitudinal moment per girder due to live load, including the effects of amplification for transverse variation in maximum longitudinal moment intensity and dynamic loading

Mg,avg = average moment per girder due to live load, determined by sharing equally the total live load moment on the bridge cross-section among all girders in the cross-section 

Mns

= moment at the end of a compression member due to loads that cause no appreciable sway, calculated using first-order elastic analysis



Ms

= moment at the end of a compression member due to loads that cause appreciable sway, calculated using first-order elastic analysis



Mx

= longitudinal bending moment per unit width

Mxy

= longitudinal torsional moment per unit width

My

= transverse bending moment per unit length

m

= for bridges of the solid cross-section type, e.g., slabs, voided slabs, and wood deck bridges that span longitudinally, the maximum longitudinal moment per metre of width due to live load

mavg

= for bridges of the solid cross-section type, e.g., slabs, voided slabs, and wood deck bridges that span longitudinally, the average longitudinal moment per metre of width due to live load

N

= number of girders or longitudinal wood beams in the bridge deck width

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n

= modular ratio, Es /E c , for steel and concrete; modular ratio of girder or beam material to slab material; number of design lanes on a bridge

P

= wheel load of the CL-625 Truck

R

= mean radius of curvature of the curved portion of a bridge that is curved in plan

RL

= modification factor for multi-lane loading in accordance with Clause 3.8.4.2

rt

= ratio of the thickness, t 1, of the deck slab at the exterior edge of a bridge deck to the thickness, t 2, at the edge of the flange of the external girder

S

= centre-to-centre spacing of longitudinal girders of a deck-on-girder bridge; centre-to-centre spacing of circular voids of a voided slab bridge; centre-to-centre spacing of spines of a multi-spine bridge



Sc

= transverse distance from the free edge of the cantilever overhang to the centreline of the web of the external girder



Se

= equivalent span of concrete deck in metres (see Clause 5.7.1.7.1)



Sp

= transverse distance of the free edge of the cantilever overhang to the supported edge (see Clause 5.7.1.6.1.1)

Sy

= transverse shear rigidity per unit length

sv

= shear area per unit length, as specified in Clause A5.2.1

t

= overall thickness of a slab

tv

= depth of circular or rectangular void in voided slabs



t1

= slab thickness at the external edge of the deck slab

t2

= slab thickness at the edge of the flange of the external girder

VT

= maximum longitudinal vertical shear for one lane width of truck or lane loading, as applicable, including dynamic load allowance

Vg

= for girder-type bridges, the maximum longitudinal vertical shear per girder due to live load, including the effects of amplification for transverse variation in maximum longitudinal vertical shear intensity and dynamic loading

Vg,avg = average shear per girder due to live load, determined by sharing equally the total live load shear on the bridge cross-section among all girders in the cross-section



Vy

= maximum intensity of transverse vertical shear in shear-connected beam bridges

v

= for slab, voided slab, and wood deck bridges that span longitudinally, the maximum longitudinal vertical shear per metre of width due to live load, including the effects of amplification for transverse variation in maximum longitudinal vertical shear intensity and dynamic loading

vavg

= average shear per metre of width due to live load for slab, voided slab, and wood deck bridges that span longitudinally, determined by sharing uniformly the total live load shear on the bridge cross-section over the width of the bridge cross-section

We

= width of a design lane, m

w

= transverse deflection of plates as used in the plate theory

x

= transverse distance between the face of the railing and the longitudinal line where moment intensity is investigated in a cantilever slab, m

x, y

= coordinates of a reference point on a cantilever slab, as shown in Figure 5.2

 s

= parameter specified in Clause 5.7.1.3



= skew parameter specified in Clause 5.6.1.1

µ

= lane width modification factor



= Poisson’s ratio

166

= moment magnification factor accounting for second-order effects of vertical load acting on a structure in a laterally displaced configuration

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

= skew angle; for orthotropic steel decks, the effective plate width factor for interior portions of the deck, as shown in Figure 5.6

p

= for orthotropic steel decks, the effective plate width factor for exterior portions of the deck, as shown in Figure 5.6

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5.4 General requirements 5.4.1 Application The requirements of Clauses 5.4.2 to 5.4.13 shall apply to bridges of all types, subject to the requirements of Clause 5.5 for certain types of short- and medium-span bridges and Clause 5.10 for long-span bridges.

5.4.2 Analysis for limit states All bridges and bridge elements shall be modelled in such a manner that their analysis accurately predicts their behaviour at each relevant limit state. For the purpose of analysis, materials shall be treated as elastic unless otherwise permitted in this Section or Approved. The elastic properties and characteristics of the materials shall be determined in accordance with Sections 8 to 10 and 16. Inelastic properties of materials may be used for analysis of structures designed to resist (a) ship impact; (b) earthquake at ultimate limit states; and (c) accidental collision forces. For inelastic behaviour, materials shall be deemed to have residual strength when strained past their elastic limit only when their behaviour is known to be ductile or, in the case of concrete, when adequate confinement reinforcement is provided in accordance with Section 4.

5.4.3 Modelling 5.4.3.1 General The geometry and structural characteristics of a bridge shall be modelled in such a manner that an analysis based on the model accurately reflects the behaviour of the bridge. Small-deflection theory or large-deflection theory shall be used for the analysis as applicable and as required by Clauses 5.4.3.2 and 5.4.3.3, respectively. The plan geometry requirements of Clause A5.1.3 shall also apply to bridge geometry modelling.

5.4.3.2 Small-deflection theory Beams, girders, trusses, braced frames, grillages, slabs, and connections designed in accordance with this Code shall be considered structures to which small-deflection theory applies. Accordingly, the effects of deflection on analysis of the structural system may be ignored.

5.4.3.3 Large-deflection theory Arch bridges, suspension bridges, cable-stayed bridges, catenaries, and frames where sidesway is permitted by this Code shall be analyzed using large-deflection theory unless analysis or past experience with similar structures indicates that small-deflection theory is adequate.

5.4.4 Structural responses Type A to K bridges (see Clause 5.1) shall be analyzed for the relevant structural responses specified in Table 5.1. Bridges of other types shall be analyzed for all of the responses specified in Table 5.1. Deformations shall be calculated in accordance with Clause 5.4.6.

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Table 5.1 Structural responses (See Clauses 5.4.4, 5.4.7, 5.5.2, 5.5.4, 5.5.5.1, 5.5.5.2, 5.5.7, and A5.1.5.)

Bridge type

Longitudinal Transverse Longitudinal Longitudinal moment moment torsion vertical shear

Transverse vertical shear

In-plane forces Requirement

A. Slab

X

X

X*†

X

X*†

—

—

B. Voided slab

X

X

X*†

X

X*†

X‡

Voids shall meet the requirements specified in Clause 5.5.2

C. Deck-on-girder

X

X

X*†

X

X*†

X‡

Longitudinal moment shall be taken by girder only or girder plus slab, depending on whether construction is non-composite or composite, respectively. Transverse moment taken by deck only (need not be considered if the deck is a slab designed in accordance with the empirical method specified in Clause 8.18.4).

D. Shear-connected beam

The bridge shall be treated as A, B, or C, as applicable X

X

X*†

X

X§

X‡

—

Without continuity of transverse flexural rigidity across the cross-section

X

X*†

X*†

X

X§

X‡

Longitudinal moment and longitudinal vertical shear shall be calculated as for multi-spine bridges of concrete construction

Truss members

—

—

—

—

—

—

The requirements of Clause 5.5.4 shall apply

Floor system

**

**

**

**

**

**

—

Arch members

—

—

—

—

—

—

The requirements of Clause 5.5.4 shall apply

Floor system

**

**

**

**

**

**

—

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With continuity of transverse flexural rigidity across the cross-section

Longitudinal Transverse Longitudinal Longitudinal moment moment torsion vertical shear

Transverse vertical shear

In-plane forces Requirement

Members supporting floor system

—

—

—

—

—

—

The requirements of Clause 5.5.4 shall apply

Floor system

**

**

**

**

**

**

—

H. Incorporating wood beams

X

X††

X*†

X

X‡‡

X§§

Live load deflections shall be considered and the requirements of Section 9 shall be followed

I. Box girder — Single cell***

X

X

X

X

X

X

—

J. Box girder — Multi-cell***

X

X

X

X

X

X

—

K. Box girder — Multi-spine***

X

X*†

X*†

X

X*†

X

—

Bridge type G. Rigid frame and integral abutment

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*Not required for dead load if the requirements of Clause 5.6.1.1 are met. †Not required for live load if the requirements of Clause 5.7.1.1 are met. ‡Applies only to prestressing. §Applies only to live load. **Using appropriate orientation, treat similarly to Type A, B, C, D, or H. ††Applies only to deck-on-stringer type. ‡‡Applies only to wood plank decks under live load. §§Applies only to prestressed wood decks. ***The requirements of Clause 5.5.7 shall apply. Torsional warping need be considered only in the case of steel and steel-composite construction. For concrete box girders, torsional warping need not be considered. Distortional warping need not be considered in the case of concrete or steel-composite construction if (a) adequate diaphragms or cross-frames are present over the supports; (b) in addition to those over the supports, a minimum of two intermediate diaphragms per span are present for concrete construction and three per span for steel-composite construction; and (c) adjacent diaphragms are spaced not more than 18 m apart in the case of concrete construction and not more than 12 m apart in the case of steel-composite construction. Note: An “X” indicates that the response shall be considered.

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5.4.5 Factors affecting structural responses In deriving the appropriate structural responses, all relevant factors in the design, both geometric and non-geometric, shall be taken into account, including, but not limited to, the following: (a) continuity of spans; (b) plan geometry, including skewness and curvature; (c) edge stiffening; (d) longitudinal variation of transverse section; (e) transverse variation of longitudinal section; (f) diaphragms and cross-frames; (g) wind bracing; (h) interaction of floor system and its support system; (i) barrier and parapet walls; (j) support boundary conditions; (k) movement of supports; (l) temperature; (m) creep, shrinkage, and relaxation; (n) elastic shortening; and (o) construction sequence. The factors specified in this Clause shall be taken account of in accordance with Annex A5.1, as applicable.

5.4.6 Deformations 5.4.6.1 General Deformations shall be calculated using material properties specified in Sections 8 to 10 and 16, as applicable. Deformations due to prestress shall be taken into account in accordance with the requirements of Clause 5.4.11.

5.4.6.2 Dead load deflections In the calculation of dead load deflection, the effects of construction sequence, prestressing, creep, and shrinkage shall be considered. The simplified method specified in Clause 5.6.1.2 may be used for bridges meeting the requirements of Clause 5.6.1.1.

5.4.6.3 Live load deflections In the absence of a more rigorous analysis, live load deflections of a bridge that satisfy the requirements of Clause 5.7.1.1 may be determined as follows: (a) Regardless of the transverse position of the live load, the average deflection of the transverse cross-section of the bridge may be determined by treating the bridge as a beam and calculating the deflection of the beam due to flexure. (b) For compliance with the deflection limitation requirements of Clause 3.4.4, the maximum deflection of the transverse cross-section of a bridge of shallow superstructure may be estimated using the method specified in Clause 5.7.1.2.2. The maximum deflection of any point on the transverse cross-section of a multi-spine box girder bridge may be estimated using the same method specified in Clause 5.7.1.2.2, in accordance with the additional requirements of Clause 5.7.1.3.

5.4.7 Diaphragms and bracing systems Diaphragms and bracing systems shall comply with the applicable requirements of Sections 8 to 10, Table 5.1, and Clause A5.1.5.

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5.4.8 Analysis of deck slabs Concrete deck slabs that are proportioned in accordance with Clause 8.18.4 need not be analyzed, except that the cantilever portions of a deck slab that are outside the outermost girders shall be analyzed in accordance with Clause 5.7.1.6.1. Concrete deck slabs not designed in accordance with Clause 8.18.4 shall be analyzed by elastic methods, except that at the ULS a yield line method may be used in lieu of elastic analysis. Deck components, other than monolithic concrete slabs designed in accordance with Clause 8.18.4, may be analyzed using elastic methods or the simplified methods specified in Clause 5.7.1.7.

5.4.9 Analysis for redistribution of force effects The effect of creep and shrinkage on redistribution of force effects shall be considered.

5.4.10 Analysis for accumulation of force effects due to construction sequence The accumulation of force effects due to the construction sequence shall be considered. For calculation of force effects at a particular stage in the construction sequence, elastic methods shall be used and the material properties shall be those appropriate to that stage of construction.

5.4.11 Analysis for effects of prestress Force effects arising from prestress, including secondary force effects in statically indeterminate structures, shall be taken into account.

5.4.12 Analysis for thermal effects Thermal effects shall be included in the analysis, as specified in Clause 3.9.

5.4.13 Secondary stability effects Secondary effects related to overall structural stability and member stability shall be included in the analysis, in accordance with Clause 5.12 and, as applicable, Sections 8 to 10 and 16.

5.5 Requirements for specific bridge types 5.5.1 General For Type A to K bridges (see Clause 5.1), the general requirements specified in Clause 5.4 shall be subject to the requirements specified in Clauses 5.5.2 to 5.5.8. For other types of bridges, engineering judgment shall be used to determine what further requirements apply.

5.5.2 Voided slab — Limitation on size of voids If a bridge is to be treated as a voided slab type, the limiting size of the voids shall be as follows: (a) For circular voids, the diameter of the void shall not exceed 80% of the total depth of the slab, and the spacing of the voids, centre-to-centre, shall not be less than the total depth of the slab. (b) For rectangular voids, the thickness of the web defined by adjacent voids shall be not less than 20% of the total depth of the section. The depth of the void shall not exceed 80% of the total depth of the section and the transverse width of the void shall not exceed 1.5 times its depth. Where the voids do not comply with the requirements of Item (a) or (b), as applicable, the bridge shall be treated as being of the multi-cell box girder type unless adequate diaphragms are provided to prevent cell distortion in accordance with Table 5.1, in which case the bridge may be treated as a voided slab.

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5.5.3 Deck-on-girder For the structural responses of deck-on-girder bridges, the following shall apply: (a) The longitudinal moment shall be assumed to be resisted only by the girders if the structural action is non-composite, and by the girders plus an appropriate portion of the deck if the structural action is composite. (b) The transverse moment shall be assumed to be taken by the deck; the action of cross-bracing or diaphragms, if present, may be taken into account.

5.5.4 Truss and arch For the structural responses of truss and arch bridges, the following shall apply: (a) The floor system shall be analyzed for the structural responses specified in Table 5.1, with the exception of longitudinal torsion, for which analysis shall be optional. (b) Axial forces for each member of the truss or arch shall be considered, including the effects of axial offset or eccentricity at panel points. (c) The overall stability of the truss shall be considered. (d) The stability of the compression chord of a pony truss shall be considered. (e) In-plane and out-of-plane buckling of components shall be considered. (f) In the analysis of long-span arches, the deflected shape of the structure shall be used in the formulation of equilibrium. Short- to medium-span arches may be analyzed using magnification correction methods.

5.5.5 Rigid frame and integral abutment types 5.5.5.1 Rigid frame For rigid frame bridges, the analysis for structural responses shall meet the requirements for slab, voided slab, deck-on-girder, or truss and arch bridges (as applicable) specified in Clauses 5.5.2 to 5.5.4 and Table 5.1, and shall also include in-plane forces and bending moments induced by frame action.

5.5.5.2 Integral abutment For integral abutment bridges, the analysis for structural responses shall meet the requirements for slab and deck-on-girder bridges (as applicable) specified in Clauses 5.5.3 and Table 5.1. The negative moment region in proximity to an integral abutment shall be established by the Engineer using appropriate methods of elastic analysis. In-plane forces and bending moments induced by frame action occurring after establishment of continuity between the superstructure and the substructure shall be included in the analysis.

5.5.6 Transverse wood deck For bridges incorporating laminated wood decks spanning transversely between longitudinal girders or stringers, only the transverse moment need be analyzed.

5.5.7 Box girder For the structural responses of box girder bridges, the following shall apply: (a) For dead load, all of the structural responses specified in Table 5.1 shall be considered. The warping and distortional effects introduced during steel and steel-composite construction shall also be considered, as shall the distortional effects that occur during construction in concrete box girders that are temporarily of open section. (b) For live load, all of the structural responses specified in Table 5.1 shall be considered. Warping and distortional effects shall be included in the analysis unless the bridge complies with the requirements of Clause 5.7 for the purposes of simplified analysis and (i) in the case of concrete and steel-composite construction, the requirements of Table 5.1 regarding diaphragms or cross-frames are met; and (ii) in the case of composite steel box girders of the multi-spine type, the requirements of Clauses 10.12.5.1 and 10.12.7 are met.

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5.5.8 Single-spine bridges A torsionally stiff, closed section single-girder superstructure may be idealized for global force effects as a single-spine beam if the ratio of the span length to the width exceeds 2.5. The width to be used in applying this criterion shall be the average distance between the outside faces of the exterior webs and the span length shall be taken as follows: (a) for simply supported bridges, the length between bearing lines; and (b) for continuous and/or skewed bridges, the length of the longest side of the rectangle that can be drawn within the plan view of the width of the smallest span. A horizontally curved, torsionally stiff single-spine superstructure may be analyzed for global force effects as a curved spine beam. The location of the centreline of such a beam shall be taken at the centre of the cross-section and the eccentricity of dead loads shall be taken into account.

5.6 Dead load 5.6.1 Simplified methods of analysis (beam analogy method) 5.6.1.1 Conditions for use For dead load analysis, the beam analogy method specified in Clause 5.6.1.2 may be used for bridges satisfying the following conditions: (a) the width is constant; (b) the support conditions are closely equivalent to line support at the ends of the bridge and, in the case of multi-span bridges, at intermediate supports; (c) for slab and voided slab bridges, the skew parameter, ε = B tan ψ/L , does not exceed 1/6, and for slab-on-girder bridges built with shored construction, the skew parameter, ε = S tan ψ/L , does not exceed 1/18, where S is the centre-to-centre spacing of longitudinal web lines or girders and B is the width of the bridge; Note: For slab-on-girder bridges built with unshored construction, no limitation on the value of the skew parameter, ε , applies.

(d) for bridges that are curved in plan and built with shored construction, the radius of curvature, span, and width satisfy the requirements of Clause A5.1.3.2; (e) slab and voided slab bridges are (i) of substantially uniform depth across a transverse section; or (ii) tapered in the vicinity of a free edge, provided that the length of the taper in the transverse direction does not exceed 2.5 m; and (f) for a bridge with longitudinal girders and an overhanging deck slab, the overhang is not more than 1.80 m and does not exceed 60% of the mean spacing between the longitudinal girders or, for box girder bridges, 60% of the spacing of the two outermost adjacent webs. When these conditions are not fully met, engineering judgment shall be used to determine whether the bridge satisfies these conditions to an extent sufficient for the beam analogy method to apply.

5.6.1.2 Description of method A bridge satisfying the requirements of Clause 5.6.1.1 shall be treated as a beam for the purpose of determining longitudinal moments, longitudinal vertical shears, and deflections due to dead load. The whole of the bridge superstructure, or that part of the bridge superstructure contained between two parallel vertical planes running in the longitudinal direction, may be considered. The dead load of the cast deck and superimposed dead load shall be distributed in accordance with engineering judgment and in a manner that satisfies overall equilibrium. Any element of superstructure in which the load is carried mainly by flexure in one direction, including but not limited to the following, may be analyzed as a beam: (a) a rectangular slab supported along two opposite edges only; (b) a rectangular slab supported along three or four edges and with a width more than twice the span;

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(c) floor beams and associated portions of a deck; and (d) stringers and associated portions of a deck.

5.6.2 Refined methods of analysis For short- and medium-span bridges, a refined method of analysis in accordance with Clause 5.9 shall be used when the requirements of Clause 5.6.1 are not met. In cases where the requirements of Clause 5.6.1 are met, a refined method in accordance with Clause 5.9 may nevertheless be used. For long-span bridges, a refined method in accordance with Clause 5.10 shall always be used.

5.7 Live load 5.7.1 Simplified methods of analysis 5.7.1.1 Conditions for use For live load analysis, the simplified methods of Clauses 5.7.1.2 to 5.7.1.5 may be used for bridges satisfying the following conditions: (a) the width is constant; (b) the support conditions are closely equivalent to line support at the ends of the bridge and, in the case of multi-span bridges, at intermediate supports; (c) for slab bridges and slab-on-girder bridges with skew, the skew parameter requirements of Clause A5.1.3.1 are met; (d) for bridges that are curved in plan, the radius of curvature, span, and width satisfy the applicable requirements of Clause A5.1.3.2; (e) slab and voided slab bridges are (i) of substantially uniform depth across a transverse section; or (ii) tapered in the vicinity of a free edge, provided that the length of the taper in the transverse direction does not exceed 2.5 m; (f) for slab-on-girder bridges, there are at least three longitudinal girders of equal flexural rigidity and equal spacing, or with variations from the mean in rigidity and spacing of not more than 10% in each case; (g) for multi-spine bridges, there are at least two longitudinal girders of nearly equal flexural rigidity and equal spacing; (h) for a bridge with longitudinal girders and an overhanging deck slab, the overhang is not more than 1.80 m and does not exceed 60% of the mean spacing between the longitudinal girders or, for box girder bridges, the spacing of the two outermost adjacent webs; (i) for a continuous span bridge, the requirements of Clause A5.1.2 are met; (j) for multi-spine bridges, each spine has only two webs, and, for steel and steel-composite multi-spine bridges, the requirements of Clause 10.12.5.1 are met; and (k) for multi-spine bridges, the number of lanes is larger than or equal to the number of spines and B/L is less than or equal to 1.0. When these conditions are not fully met, engineering judgment shall be used to determine whether the bridge satisfies these conditions to an extent sufficient for the appropriate simplified method to apply. For the purpose of using simplified methods of analysis for live load, superstructure types shall be categorized as specified in Table 5.2.

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Table 5.2 Superstructure categories for simplified methods of analysis for live load (See Clause 5.7.1.1.) Category

Type of superstructure

Applicable Clauses

Shallow superstructure

Slab Voided slab that complies with Clause 5.5.2* Slab-on-girder Steel-grid-deck-on-girder Wood-deck-on-girder Wood deck on longitudinal wood beam Stress-laminated wood deck bridge spanning longitudinally Longitudinal nail-laminated wood deck bridge Longitudinal laminates of wood-concrete composite decks

5.7.1.2 (longitudinal moment) 5.7.1.4 (longitudinal vertical shear)

Shear-connected-beam bridge in which the interconnection of adjacent beams is such as to provide continuity of transverse flexural rigidity across the cross-section.

5.7.1.2 (longitudinal moment) 5.7.1.4 (longitudinal vertical shear) 5.7.1.8 (transverse vertical shear)

Box girder bridge in which the boxes are connected only by the deck slab and transverse diaphragms, if present. The bottom flanges of the boxes are discontinuous.

5.7.1.3 (longitudinal moment) 5.7.1.5 (longitudinal vertical shear)

Shear-connected beam bridge in which the interconnection of adjacent beams is such as not to provide continuity of transverse flexural rigidity across the cross-section.

5.7.1.3 (longitudinal moment) 5.7.1.5 (longitudinal vertical shear) 5.7.1.8 (transverse vertical shear)

Multi-spine bridge

*Multi-cell box girders with diaphragms in accordance with Clause 5.4.4 may be treated as voided slabs for the purposes of simplified methods of analysis; otherwise, a refined method of analysis in accordance with Clause 5.9 shall be used.

5.7.1.2 Longitudinal bending moments in shallow superstructures 5.7.1.2.1 Longitudinal bending moments for ultimate and serviceability limit states 5.7.1.2.1.1 For a bridge classified as a shallow superstructure and satisfying all of the applicable conditions listed in Clause 5.7.1.1, the method specified in Clause 5.7.1.2.1.2 may be used for obtaining governing live load moments in the internal and external portions of the bridge in the absence of a more refined method.

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5.7.1.2.1.2 Longitudinal bending moment diagrams shall be obtained by treating the bridge as a beam for two load cases. The first load case shall comprise one truck consisting of two lines of wheels as specified in Clause 3.8.3.2, multiplied by the appropriate factor (1 + DLA) specified in Clause 3.8.4.5. The second load case shall comprise the lane load specified in Clause 3.8.3.3. The governing moments per design lane thus obtained shall be designated MT . The following requirements shall also apply: (a) For girder-type bridges and bridges with longitudinal wood beams, the longitudinal moment per girder, Mg, shall be calculated as follows: Mg = Fm Mg,avg where Fm

= amplification factor to account for the transverse variation in maximum longitudinal moment intensity, as compared to the average longitudinal moment intensity

SN ≥ 1.05 ⎡ mCf ⎤ F ⎢1+ ⎣ 100 ⎥⎦ where S = centre-to-centre girder spacing, m F = width dimension that characterizes load distribution for a bridge, m =

⎡ mCf ⎤ ⎢⎣1+ 100 ⎥⎦ = lane width correction factor where We − 3.3 ≤ 1.0 0 .6 where We = width of design lane, m, calculated in accordance with Clause 3.8.2

μ

=

Cf

= percentage correction factor obtained from Table 5.3

For bridges with Sc greater than 0.5S, Fm for external girders shall be multiplied by 1.05. Mg,avg = average moment per girder due to live load determined by sharing equally the total moment on the bridge cross-section among all girders in the cross-section

nMT RL N where n = number of design lanes in accordance with Clause 3.8.2 = maximum moment per design lane at the point of the span under consideration, as MT specified in this Clause = modification factor for multi-lane loading in accordance with RL Clause 3.8.4.2 or 14.9.4.2 N = number of girders or longitudinal wood beams in the bridge deck width, B F and Cf shall be obtained from Table 5.3 for bridges with up to four design lanes, for both the internal and external portions of the cross-section, both of which shall be obtained corresponding to the type of bridge, the class of highway, number of design lanes, and the span, L. The span, L, for continuous spans shall be as specified in Clause A5.1.2. For bridges with more than four design lanes, the value of F shall be calculated as follows: =

F = F4

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where F4 = value of F for four design lanes obtained from Table 5.3 and the value for Cf obtained from Table 5.3 for n = 4 shall be used without modification. (b) For slab bridges, voided slab bridges, and wood deck bridges that span longitudinally, the moment per metre of width, m, shall be calculated as follows: m = Fm mavg where Fm

=

B ≥ 1.05 ⎡ mCf ⎤ F ⎢1+ ⎣ 100 ⎥⎦

where B mavg =

= total width of bridge, regardless of whether tapered edges are present

nMT RL Be

where = effective width of the bridge, calculated by reducing the total width, B, for the effects of tapered edges, if present, as specified in Clause A5.1.4 F and Cf shall be obtained from Table 5.3 and F shall be modified for bridges with more than four design lanes in accordance with Clause 5.7.1.2.1.2(a). Be

Table 5.3 F and Cf for longitudinal bending moments in shallow superstructures corresponding to ultimate and serviceability limit states (See Clauses 5.7.1.2.1.2 and 5.7.1.2.2.2.) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes Type A or B

F, m

Portion

3 m < L ≤ 10 m

1

External Internal

3.80 + 0.04L 4.00 + 0.04L

4.20 4.40

16 – (36/L) 16 – (36/L)

2

External Internal

7.10 7.60 – (6/L)

7.10 7.30 – (3/L)

20 – (40/L) 20 – (40/L)

3

External Internal

7.90 + 0.21L 5.90 + 0.41L

10.80 – (8/L) 10.80 – (8/L)

16 – (30/L) 16 – (30/L)

4

External Internal

10.10 + 0.26L 7.40 + 0.56L

14.30 – (16/L) 14.00 – (10/L)

16 – (30/L) 16 – (30/L)

C or D (for 1 evaluation only)

External Internal

3.80 + 0.04L 4.00 + 0.04L

4.20 4.40

16 – (36/L) 16 – (36/L)

2

External Internal

7.10 7.60 – (6/L)

7.10 7.30 – (3/L)

20 – (40/L) 20 – (40/L)

3

External Internal

7.90 + 0.21L 6.20 + 0.38L

10.80 – (8/L) 10.80 – (8/L)

16 – (30/L) 16 – (30/L)

4

External Internal

— —

— —

A or B (for design of new bridges or evaluation)

— —

L > 10 m

Cf , %

(Continued)

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Table 5.3 (Continued) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes

Portion

3 m < L ≤ 10 m

Type C slab-on-girder

1

External Internal

3.30 3.30 + 0.05L

3.50 – (2/L) 4.40 – (6/L)

5 – (12/L) 5 – (12/L)

2

External Internal

6.50 4.80 + 0.10L

6.80 – (3/L) 7.20 – (14/L)

10 – (25/L) 10 – (25/L)

3

External Internal

8.30 6.70 + 0.08L

8.70 – (4/L) 9.60 – (21/L)

10 – (25/L) 10 – (25/L)

4

External Internal

9.50 7.60 + 0.14L

10.00 – (5/L) 11.20 – (22/L)

10 – (25/L) 10 – (25/L)

C or D (for 1 evaluation only)

External Internal

3.30 3.30 + 0.05L

3.50 – (2/L) 4.40 – (6/L)

5 – (12/L) 5 – (12/L)

2

External Internal

6.10 4.80 + 0.10L

6.40 – (3/L) 7.20 – (14/L)

5 – (15/L) 5 – (15/L)

3

External Internal

7.70 6.60 + 0.04L

8.10 – (4/L) 8.80 – (18/L)

10 – (25/L) 10 – (25/L)

4

External Internal

1

External Internal

3.40 2.80 + 0.06L

3.40 4.20 – (8/L)

0 0

2

External Internal

6.30 5.40

6.30 7.90 – 125/(L + 40)

0 0

3

External Internal

8.40 7.20

8.40 10.60 – 170/(L + 40)

0 0

4

External Internal

9.80 8.40

9.80 12.30 – 195/(L + 40)

0 0

C or D (for 1 evaluation only)

External Internal

3.40 2.80 + 0.06L

3.40 4.20 – (8/L)

0 0

2

External Internal

6.00 5.40

6.00 7.90 – 125/(L + 40)

0 0

3

External Internal

7.40 6.70

7.40 9.80 – 155/(L + 40)

0 0

4

External Internal

Type C with 140 mm laminated wood deck*

A or B (for design of new bridges or evaluation)

A or B (for design of new bridges or evaluation)

F, m

— —

— —

L > 10 m

Cf , %

— —

— —

— —

— — (Continued)

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Table 5.3 (Continued) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes Type C with 290 mm laminated wood deck*

Type C steel-griddeck-on-girder with deck less than 100 mm thick

F, m

Portion

3 m < L ≤ 10 m

1

External Internal

3.50 3.30 + 0.05L

3.50 4.80 – 20/(L + 10)

2

External Internal

6.30 5.20 + 0.07L

6.30 7.30 – (14/L)

3

External Internal

8.60 7.10 + 0.12L

8.60 10.0 – (17/L)

10 – (25/L) 10 – (25/L)

4

External Internal

10.10 8.30 + 0.14L

10.10 11.70 – (20/L)

10 – (25/L) 10 – (25/L)

C or D (for 1 evaluation only)

External Internal

3.50 3.30 + 0.05L

3.50 4.80 – 20/(L + 10)

2

External Internal

6.00 5.20 + 0.07L

6.00 7.30 – (14/L)

10 – (25/L) 10 – (25/L)

3

External Internal

7.50 6.60 + 0.11L

7.50 9.20 – (15/L)

10 – (25/L) 10 – (25/L)

4

External Internal

— —

— —

— —

1

External or Internal

2.70

2.70

0

2

External or Internal

4.80

4.80

0

3

External or Internal

6.50

6.50

0

4

External or Internal

7.60

7.60

0

C or D (for 1 evaluation only)

External or Internal

2.70

2.70

0

2

External or Internal

4.80

4.80

0

3

External or Internal

6.00

6.00

0

4

External or Internal

—

—

—

A or B (for design of new bridges or evaluation)

A or B (for design of new bridges or evaluation)

L > 10 m

Cf , % 0 5 – (12/L) 10 – (25/L) 10 – (25/L)

0 5 – (12/L)

(Continued)

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Table 5.3 (Continued) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes Type C steel-griddeck-on-girder with deck 100 mm thick or thicker

F, m

Portion

3 m < L ≤ 10 m

L > 10 m

Cf , %

1

External or Internal

3.60

3.60

0

2

External or Internal

6.10

6.10

0

3

External or Internal

8.10

8.10

0

4

External or Internal

9.50

9.50

0

C or D (for 1 evaluation only)

External or Internal

3.60

3.60

0

2

External or Internal

6.10

6.10

0

3

External or Internal

7.50

7.50

0

4

External or Internal

—

—

—

1

External or Internal

2.40

2.40

0

2

External or Internal

4.60

4.60

0

3

External or Internal

6.10

6.10

0

4

External or Internal

7.20

7.20

0

C or D (for 1 evaluation only)

External or Internal

2.40

2.40

0

2

External or Internal

4.60

4.60

0

3

External or Internal

5.70

5.70

0

4

External or Internal

—

—

—

A or B (for design of new bridges or evaluation)

Type C with A or B (for wood plank deck design of new bridges or evaluation)

(Continued)

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Table 5.3 (Continued) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes Type H sawn wood stringer bridge

Type H stress-laminated wood deck bridge spanning longitudinally

F, m

Portion

3 m < L ≤ 10 m

L > 10 m

Cf , %

1

External or Internal

3.60

—

0

2

External or Internal

4.70 + 0.14L

—

0

3

External or Internal

6.20 + 0.19L

—

0

4

External or Internal

7.30 + 0.22L

—

0

C or D (for 1 evaluation only)

External or Internal

3.60

—

0

2

External or Internal

4.70 + 0.14L

—

0

3

External or Internal

5.70 + 0.18L

—

0

4

External or Internal

—

—

—

1

External or Internal

3.10 + 0.08L

3.10 + 0.08L

0

2

External or Internal

4.70 + 0.12L

4.70 + 0.12L

0

3

External or Internal

6.20 + 0.16L

6.20 + 0.16L

0

4

External or Internal

7.30 + 0.19L

7.30 + 0.19L

0

C or D (for 1 evaluation only)

External or Internal

3.10 + 0.08L

3.10 + 0.08L

0

2

External or Internal

4.70 + 0.12L

4.70 + 0.12L

0

3

External or Internal

5.80 + 0.15L

5.80 + 0.15L

0

4

External or Internal

—

—

—

A or B (for design of new bridges or evaluation)

A or B (for design of new bridges or evaluation)

(Continued)

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Table 5.3 (Concluded) Highway class (see Clause 1.4.2.2) No. of Bridge type and design (see Clause 5.1) applicability lanes Type H longitudinal nail-laminated wood deck bridge

Type H longitudinal laminates of wood-concrete composite deck bridge

F, m

Portion

3 m < L ≤ 10 m

L > 10 m

Cf , %

1

External or Internal

1.70

1.70

0

2

External or Internal

3.10

3.10

0

3

External or Internal

4.10

4.10

0

4

External or Internal

4.80

4.80

0

C or D (for 1 evaluation only)

External or Internal

1.70

1.70

0

2

External or Internal

2.90

2.90

0

3

External or Internal

3.60

3.60

0

4

External or Internal

—

—

—

1

External or Internal

3.20

3.20

0

2

External or Internal

6.00

6.00

0

3

External or Internal

8.00

8.00

0

4

External or Internal

9.30

9.30

0

C or D (for 1 evaluation only)

External or Internal

3.20

3.20

0

2

External or Internal

6.00

6.00

0

3

External or Internal

7.40

7.40

0

4

External or Internal

—

—

—

A or B (for design of new bridges or evaluation)

A or B (for design of new bridges or evaluation)

*For girder bridges with laminated wood decks not 140 or 290 mm thick, linear interpolation based on the values for 140 and 290 mm decks shall be used. Note: Only Class A highways shall be used for determining F values for the design of new bridges. In the evaluation of existing bridges, Class A, B, C, or D highways may be used for determining F values, in accordance with the requirements of the Regulatory Authority.

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5.7.1.2.2 Longitudinal bending moments and associated deflections for fatigue limit state and superstructure vibration 5.7.1.2.2.1 For a bridge classified as a shallow superstructure and satisfying all of the applicable conditions listed in Clause 5.7.1.1, the method specified in Clause 5.7.1.2.2.2 may be used for obtaining governing longitudinal moments in the absence of a more refined method.

5.7.1.2.2.2 The following requirements shall apply: (a) The values of F, Cf , and Ce shall be obtained using Tables 5.4 and 5.5 for the internal and external portions of the cross-section, in accordance with the type of bridge, the number of design lanes, the span, L, and, in the case of slab-on-girder bridges, the vehicle edge distance, DVE , as shown in Figure 5.1. For bridges other than the slab-on-girder type, there shall be no need to consider DVE . When the value of DVE is greater than 3.00 m, it shall be taken as 3.00 m for the purposes of this Clause. The span, L, for continuous spans shall be as specified in Clause A5.1.2. (b) The longitudinal bending moments and deflections shall be calculated by treating the bridge as a beam loaded by two lines of wheels that comprise one truck, as specified in Clause 3.8.3.2. The bending moments and deflections shall be multiplied by (1 + DLA), where DLA is the relevant dynamic load allowance for a single vehicle or portion of a vehicle, as applicable, to obtain the live load longitudinal bending moments and deflections for the entire cross-section of the bridge. The governing moments thus obtained shall be designated MT , which shall be distributed in the cross-section in accordance with Item (c). (c) For girder-type bridges and bridges with longitudinal wood beams, the longitudinal moment per girder, Mg , shall be calculated as follows: Mg = Fm Mg,avg where Fm

= amplification factor to account for the transverse variation in maximum longitudinal moment intensity, as compared to the average longitudinal moment intensity =

SN ≥ 1.05 Cf C ⎤ m ⎡ F ⎢1+ + e ⎥ ⎣ 100 100 ⎦

where S

= centre-to-centre girder spacing, m

F

= width dimension that characterizes load distribution for a bridge, obtained from Table 5.4. For the internal girders of slab-on-girder bridges consisting of two or more lanes, the value of F obtained from Table 5.4 shall be modified by the following factor, which accounts for the variation of F with girder spacing S: For 10 m ≤ L ≤ 50 m:

⎡ ⎡ L − 10 ⎤ ⎤ F = Ftab ⎢1.00 + ( 0.29S − 0.35) ⎢ ⎥ ⎣ 40 ⎥⎦ ⎦ ⎣ For L > 50 m: F = Ftab (0.29S + 0.65) where Ftab is the value of F for the internal girders from Table 5.4 and the girder spacing, S, is limited to 1.2 m ≤ S ≤ 3.6 m. A value of 3.6 m shall be used for S if S exceeds 3.6 m.

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We − 3.3 ≤ 1.0 0 .6 where We = width of design lane, m, calculated in accordance with Clause 3.8.2

μ

=

Cf

= percentage correction factor obtained from Table 5.4

Ce

= percentage correction factor for vehicle edge distance obtained from Table 5.5

For bridges with Sc greater than 0.5S, Fm for external girders shall be multiplied by 1.05. Mg,avg = average moment per girder determined by sharing equally the total moment on the bridge cross-section among all girders in the cross-section = MT /N where MT

= maximum moment for one truck at the point of the span under consideration, as specified in Item (b)

N

= number of girders or longitudinal wood beams in the bridge deck width, B

The amplification factor, Fm , shall apply to the calculation of maximum deflection. The maximum deflection of a girder for satisfying superstructure vibration requirements shall be determined by applying (Fm / N ) trucks per girder and using the appropriate stiffness characteristics of the girder. (d) For slab bridges, voided slab bridges, and wood deck bridges that span longitudinally, the moment per metre of width, m, shall be calculated as follows: m = Fm mavg where Fm

=

B ≥ 1.05 ⎡ mCf ⎤ F ⎢1+ ⎣ 100 ⎥⎦

where B

= total width of the bridge, regardless of whether tapered edges are present

mavg = MT /Be where Be

= effective width of the bridge, calculated by reducing the total width, B, for the effects of tapered edges, if present, as specified in Clause A5.1.4

F and Cf shall be obtained from Table 5.4 and the amplification factor, Fm , shall apply to the calculation of maximum deflection. The maximum deflection of a point on the transverse section of a slab or voided slab bridge for satisfying superstructure vibration requirements shall be determined by applying (Fm / B ) trucks per metre of width and using the appropriate stiffness characteristics of a 1 m wide section of slab.

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Table 5.4 F and Cf for longitudinal bending moments in shallow superstructures corresponding to the fatigue limit state (See Clause 5.7.1.2.2.2.)



Bridge type (see Clause 5.1)

No. of design lanes

Type A or B

Type C slab-on-girder

Portion

3 m < L  10 m

1

External Internal

3.80 + 0.04L 4.00 + 0.04L

4.20 4.40

16 – (36/L) 16 – (36/L)

2

External Internal

3.60 + 0.26L 3.20 + 0.30L

7.00 – (8/L) 6.40 – (2/L)

16 – (36/L) 16 – (36/L)

3

External Internal

3.30 + 0.30L 3.00 + 0.40L

9.60 – (33/L) 9.80 – (29/L)

16 – (36/L) 12 – (36/L)

4 or more

External Internal

3.40 + 0.30L 3.00 + 0.44L

12.00 – (56/L) 12.00 – (46/L)

10 – (30/L) 10 – (30/L)

1

External Internal

3.30 3.30 + 0.05L

3.50 – (2/L) 4.40 – (6/L)

5 – (12/L) 5 – (12/L)

2

External Internal

3.60 2.80 + 0.12L

3.80 – (2/L) 4.60 – (6/L)

5 – (15/L) 5 – (15/L)

3

External

3.60 + 0.01L

4 or more

Type C with 140 mm laminated wood deck*

Type C with 290 mm laminated wood deck*

F, m

Internal

2.80 + 0.12L

External

3.80

L > 10 m

3.70 +

(L − 10 )

140 4.80 – (8/L)

3.80 +

(L − 10 )

Cf , %

0 0 0

Internal

2.80 + 0.12L

140 5.00 – (10/L)

1

External Internal

3.40 2.80 + 0.06L

3.40 4.20 – (8/L)

0 0

2

External Internal

3.60 3.00 + 0.06L

3.80 – (2/L) 4.40 – (8/L)

0 0

3

External Internal

3.60 3.00 + 0.06L

3.80 – (2/L) 4.40 – (8/L)

0 0

4 or more

External Internal

3.60 3.00 + 0.06L

3.80 – (2/L) 4.40 – (8/L)

0 0

1

External Internal

3.50 3.30 + 0.05L

3.50 4.80 – 20/(L + 10)

0 5 – (12/L)

2

External Internal

3.50 + 0.02L 3.30 + 0.05L

3.90 – (2/L) 5.40 – 3.20 L − 6

6 – (15/L) 6 – (15/L)

3

External Internal

3.50 + 0.02L 3.40 + 0.06L

3.90 – (2/L) 5.50 – 1350/(L + 20)2

10 – (21/L) 10 – (21/L)

4 or more

External Internal

3.50 + 0.02L 3.60 + (L2/200)

3.90 – (2/L) 6.00 – (19/L)

10 – (21/L) 10 – (21/L)

0

(Continued)

May 2010 (Replaces p. 185, November 2006)

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Table 5.4 (Continued) Bridge type (see Clause 5.1)

No. of design lanes

Portion

3 m < L ≤ 10 m

L > 10 m

Cf , %

External or Internal

2.70

2.70

0

External or Internal

2.80

2.80

0

3

External or Internal

2.80

2.80

0

4 or more

External or Internal

2.80

2.80

0

1

External or Internal

3.60

3.60

0

2

External or Internal

3.70

3.70

0

3

External or Internal

3.70

3.70

0

4 or more

External or Internal

3.70

3.70

0

1

External or Internal

2.40

2.40

0

2

External or Internal

2.40

2.40

0

3

External or Internal

2.40

2.40

0

4 or more

External or Internal

2.40

2.40

0

1

External or Internal

3.60

—

0

2

External or Internal

3.70

—

0

3 or more

External Internal

3.70 3.80

— —

0 0

1

External or Internal

3.10 + 0.08L

3.10 + 0.08L

0

2 or more

External or Internal

3.40 + 0.07L

3.40 + 0.07L

0

1 or more

External or Internal

1.70

—

0

Type C steel-grid-deck- 1 on-girder with deck less than 100 mm thick 2

Type C steel-grid-deckon-girder with deck 100 mm thick or thicker

Type C with wood plank deck

Type H sawn wood stringer bridge

Type H stress-laminated wood deck bridge spanning longitudinally Type H longitudinal nail-laminated wood deck bridge

F, m

(Continued)

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Canadian Highway Bridge Design Code

Table 5.4 (Concluded) No. of design lanes

Bridge type (see Clause 5.1) Type H longitudinal laminates of wood-concrete composite deck bridge

F, m Portion

3 m < L ≤ 10 m

L > 10 m

Cf , %

1

External or Internal

3.20

3.20

0

2

External or Internal

3.30

3.30

0

3

External or Internal

3.30

3.30

0

4 or more

External or Internal

3.30

3.30

0

*For girder bridges with laminated wood decks not 140 or 290 mm thick, linear interpolation based on the values for 140 and 290 mm decks shall be used.

Table 5.5 Ce for longitudinal bending moments in shallow superstructures corresponding to the fatigue and vibration limit state (See Clause 5.7.1.2.2.2.)

Bridge type (see Clause 5.1) Type C slab-on-girder

No. of design lanes

Portion

3 m < L ≤ 20 m

L > 20 m

1

External Internal

0 0

0 0

2

External

30(DVE –1)[1 + 0.4(DVE –1)2]

⎡ 160 (DVE − 1)2 ⎤ 30 (DVE − 1) ⎢1 + ⎥ L2 ⎣ ⎦

Internal

0

0

External

26(DVE –1)[1 + 0.4(DVE –1)2]

⎡ 160 (DVE − 1)2 ⎤ 26 (DVE − 1) ⎢1 + ⎥ L2 ⎣ ⎦

Internal

0

0

External

26(DVE –1)[1 + 0.4(DVE –1)2]

⎡ 160 (DVE − 1)2 ⎤ 26 (DVE − 1) ⎢1 + ⎥ L2 ⎣ ⎦

Internal

0

0

External or Internal

0

0

3

4 or more

Other types

November 2006

Ce , %

1 or more

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Centreline of travelled lane and centreline of truck DVE

_ 0.6S <

S

DVE

Figure 5.1 for slab-on-girder bridges (See Clause 5.7.1.2.2.2.)

5.7.1.3 Longitudinal bending moments in multi-spine bridges 5.7.1.3.1 If all of the applicable conditions listed in Clause 5.7.1.1 are satisfied, the simplified method specified in Clause 5.7.1.3.2 may be used for multi-spine bridges.

5.7.1.3.2

The value of β shall be calculated as follows:

⎡B b = π⎢ ⎣L

⎤ ⎡ Dx ⎤ ⎥ ⎢D ⎥ ⎦ ⎢⎣ xy ⎥⎦

0.5

where B

= for ultimate and serviceability limits states, the width of the bridge = for the fatigue limit state, the width of the bridge, but not greater than three times the spine spacing, S

Dx

= total bending stiffness, EI, of the bridge cross-section divided by the width of the bridge

Dxy

= total torsional stiffness, GJ, of the bridge cross-section divided by the width of the bridge

The longitudinal bending moment per spine shall be calculated using the methods specified in Clause 5.7.1.2.1 for the ultimate and serviceability limit states and in Clause 5.7.1.2.2 for the fatigue limit state, except that S shall be taken as the centreline-to-centreline spacing of the spines and the applicable values of F and Cf shall be obtained from Table 5.6. No distinction shall be made between internal and external portions of the cross-section, and the value of Ce shall be taken as zero. At ultimate and serviceability limit states for bridges with more than four design lanes, the value of F shall be calculated as follows:

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© Canadian Standards Association

F = F4

Canadian Highway Bridge Design Code

nRL 2.80

where F4

=

value of F for four design lanes obtained from Table 5.6

Table 5.6 F and Cf for longitudinal moments in multi-spine bridges (See Clause 5.7.1.3.2.)

Limit state

Number of design lanes

F, m

Cf , %

ULS or SLS

2 3 4

8.5 – 0.3β 11.5 – 0.5β 14.5 – 0.7β

16 – 2β 16 – 2β 16 – 2β

FLS

2 or more

8.5 – 0.9β

16 – 2β

5.7.1.4 Longitudinal vertical shear in shallow superstructures 5.7.1.4.1 Longitudinal vertical shear for ultimate and serviceability limit states 5.7.1.4.1.1 For a bridge classified as a shallow superstructure and satisfying all of the applicable conditions listed in Clause 5.7.1.1, the method specified in Clause 5.7.1.4.1.2 may be used for obtaining governing live load shears in the internal and external portions of the bridge.

5.7.1.4.1.2 Longitudinal vertical shear diagrams shall be obtained by treating the bridge as a beam for two load cases. The first load case shall comprise one truck consisting of two lines of wheels, as specified in Clause 3.8.3.2, multiplied by the appropriate factor (1 + DLA) specified in Clause 3.8.4.5. The second load case shall comprise the lane load specified in Clause 3.8.3.3. The governing shears per design lane thus obtained shall be designated VT . The following requirements shall also apply: (a) For girder-type bridges and bridges with longitudinal wood beams, the longitudinal vertical shear per girder, Vg , shall be calculated as follows: Vg = FvVg,avg where = amplification factor to account for the transverse variation in maximum longitudinal vertical Fv shear intensity, as compared to the average longitudinal vertical shear intensity = SN/F where S

= centre-to-centre girder spacing, m

F

= width dimension that characterizes load distribution for a bridge

Vg,avg = average shear per girder determined by sharing equally the total shear on the bridge cross-section among all girders in the cross-section nVT RL = N

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where n

= number of design lanes in accordance with Clause 3.8.2

VT

= maximum shear per design lane at the point of the span under consideration, as specified in this Clause

RL

= modification factor for multi-lane loading in accordance with Clause 3.8.4.2 or 14.9.4.2

N

= number of girders or longitudinal wood beams in the bridge deck width, B

For bridges with up to four design lanes, F shall be obtained from Table 5.7. For girder-type bridges, where the spacing, S, of longitudinal girders is less than 2.00 m, the value of F obtained from Table 5.7 shall be multiplied by (S/2)0.25. This reduction factor shall not apply to solid slabs, transversely prestressed laminated-wood bridges, or longitudinal laminates of wood-concrete composite decks. For bridges with more than four design lanes, the value of F shall be calculated as follows:

F = F4

nRL 2.80

where F4

= v alue of F for four design lanes obtained from Table 5.7 and multiplied by (S/2)0.25 if S is less than 2.00 m

(b) For slab bridges, voided slab bridges, and wood deck bridges that span longitudinally, the longitudinal vertical shear per metre of width, v, shall be calculated as follows: v = Fvvavg where = B/F ≥ 1.05

Fv

where B

= total width of the bridge, regardless of whether tapered edges are present

F

= width dimension that characterizes load distribution for a bridge, obtained from Table 5.7

nVT RL Be where Be = effective width of the bridge, calculated by reducing the total width, B , for the effects of tapered edges, if present, as specified in Clause A5.1.4 For voided slab bridges where the centre-to-centre spacing, S, of longitudinal web lines is less than 2.00 m, the value of F obtained from Table 5.7 shall be multiplied by (S/2)0.25. For bridges with more than four design lanes, the value of F shall be calculated as follows: vavg

=

F = F4

nRL 2.80

where F4

190

= v alue of F for four design lanes obtained from Table 5.7 and multiplied by the factor (S/2)0.25 if S is less than 2.00 m

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

Table 5.7 F for longitudinal vertical shear corresponding to ultimate and serviceability limit states, m (See Clause 5.7.1.4.1.2.) Number of design lanes and class of highway 1

2

3

All classes

All classes

Class A or B

Class C or D

Class A or B

Type A

2.60 + 0.45 L

4.20 + 0.66 L

5.60 + 1.05 L

5.20 + 0.97 L

6.50 + 1.44 L

Type B

3.60

6.30

8.40

7.80

9.80

Slab-on-girder

3.50

6.10

8.20

7.60

9.50

With laminated wood deck

3.00*

5.40*

7.20*

6.60*

8.40*

With plank wood deck

2.40*

4.60*

6.10*

5.70*

7.20*

Deck less than 100 mm thick

2.30*

4.30*

5.80*

5.40*

6.70*

Deck 100 mm thick or thicker

3.00*

5.50*

7.40*

6.80*

8.50*

Longitudinal wood beams with transverse laminated wood deck

3.30*

5.70*

7.60*

7.00*

8.90*

Stress-laminated wood deck bridge spanning longitudinally

3.30

5.10

6.80

6.30

7.90

Longitudinal nail-laminated wood deck bridge

1.70

3.10

4.10

3.60

4.80

Longitudinal laminates of wood-concrete composite deck bridge

2.60

4.80

6.50

6.00

7.60

Bridge type (see Clause 5.1)

4

Type C

Steel-grid-deckon-girder

Type H

*These values of F are the maximums to be used for internal and external girders. In addition, for external girders, the load shall be the reaction of the wheel loads, assuming that the flooring between the stringers acts as a simple beam, but F shall not be greater than the value specified for internal girders.

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5.7.1.4.2 Longitudinal vertical shear for fatigue limit state For a bridge satisfying all of the applicable conditions listed in Clause 5.7.1.1, live load longitudinal vertical shear may be calculated using the method specified in Clause 5.7.1.4.1, except that the values of F shall be obtained from Table 5.8 and VT shall be calculated using a single truck on the bridge, in one lane only, such that n = 1 and RL = 1.00.

Table 5.8 F for longitudinal vertical shear corresponding to fatigue limit state, m (See Clause 5.7.1.4.2.) Number of design lanes Bridge type (see Clause 5.1)

1

2

3

4

Type A

2.60 + 0.45 L

3.20 + 0.13L

3.20 + 0.16L

3.60 + 0.14L

Type B

3.60

3.60

3.80

3.90

Slab-on-girder

3.50

3.60

3.60

3.70

With laminated wood deck

3.00*

3.30*

3.30*

3.30*

With plank wood deck

2.40*

2.50*

2.50*

2.50*

Deck less than 100 mm thick

2.30*

2.40*

2.40*

2.40*

Deck 100 mm thick or thicker

3.00*

3.10*

3.10*

3.10*

Longitudinal wood beams with transverse laminated wood deck

3.30*

3.50*

3.50*

3.60*

Stress-laminated wood deck bridge spanning longitudinally

3.30

3.50

3.70

3.70

Longitudinal nail-laminated wood deck bridge

1.70

1.70

1.70

1.70

Longitudinal laminates of wood-concrete composite deck bridge

2.60

2.80

2.80

2.80

Type C

Steel-grid-deck-on-girder

Type H

*These values of F are the maximums to be used for internal and external girders. In addition, for external girders, the load shall be the reaction of the wheel loads, assuming that the flooring between the stringers acts as a simple beam, but F shall not be greater than the value specified for internal girders.

5.7.1.5 Longitudinal vertical shear in multi-spine bridges 5.7.1.5.1 If all of the applicable conditions listed in Clause 5.7.1.1 are satisfied, the simplified method specified in Clause 5.7.1.5.2 may be used.

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© Canadian Standards Association

5.7.1.5.2 For bridges with up to four design lanes, the value of F for longitudinal vertical shear shall be obtained from Table 5.9. The method specified in Clause 5.7.1.4 for the applicable limit state shall be used, with S being the centreline-to-centreline spacing of spines and N the number of spines; the shear thus obtained shall be for one spine. The shear force determined for one spine shall be equally distributed to the two webs of the spine. The value of Fv for the purposes of this Clause shall be such that Fv is greater than or equal to Fm . At ultimate and serviceability limit states for bridges with more than four design lanes, the value of F shall be calculated as follows:

nRL 2.80

F = F4 where F4

= value of F for four design lanes obtained from Table 5.9

Table 5.9 F for longitudinal vertical shear in multi-spine bridges (See Clause 5.7.1.5.2.) Limit state

Number of design lanes

F, m

ULS or SLS

2 3 4

7.2 9.6 11.2

FLS

2 or more

4.25

5.7.1.6 Deck slab moments due to loads on the cantilever overhang 5.7.1.6.1 Transverse moments due to wheel loads on the cantilever overhang 

5.7.1.6.1.1 Transverse moments in the cantilever overhang For a cantilever slab of constant or linearly varying thickness, the intensity of transverse moment My due to a concentrated load P shall be calculated as follows:

My =

2PA ⎡ ⎛ Ax ⎞ 2 ⎤ π ⎢1+ ⎜ ⎟ ⎥ ⎢⎣ ⎝ C − y ⎠ ⎥⎦

2

where A

= coefficient obtained from Figure 5.2

C

= transverse distance of the load from the supported edge of the cantilever slab

and x and y are the coordinates shown in Figure 5.2, with y less than C. The relevant design moment intensity shall be obtained by multiplying My by (1 + DLA). For the design moment intensity due to the vertical axle loads of the CL-625 Truck, the effects of individual loads shall be obtained and superimposed or, alternatively, the design moment intensity due to the CL-625 Truck may be obtained directly, without calculation, from Table 5.10 for stiffened and unstiffened overhangs, as applicable (Table 5.10 includes the factor [1 + DLA]). Edge stiffening is provided

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by a continuous concrete barrier. Barriers shall be continuously longitudinally reinforced and have a stiffness equal to or greater than provided by New Jersey barriers. For those portions of the cantilever slab that are within a distance Sp of a transverse free edge of the slab, the transverse moment intensity shall be assumed to be 2My unless a more rigorous analysis is used. Sp is the transverse distance measured from the free edge of the cantilever overhang to the supported edge. The supported edge may be determined from Figure 5.1A for different types of superstructures.

Sp

Se

Se

Se

45°

45°

Se

Sp

45°

Sp

Sp



Figure 5.1A Definition of Sp and Se

(See Clauses 5.7.1.6.1.1 and 5.7.1.7.1.)

5.7.1.6.1.2 Transverse moments in the interior panel next to the cantilever overhang In the absence of a more refined method of analysis, the transverse moments in the interior panel next to the cantilever overhang may be assumed to vary linearly from the values calculated in accordance with Clause 5.7.1.6.1.1 at the root of the cantilever overhang to zero at the girder next to the exterior girder.

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Unsupported edge Applied load P

Point evaluated

P C

x

C

y

Sp

t1

t2 Sp

Supported edge

rt = t1/t2

Note: x and y are positive values. 1.2

1.2

y=0 y = 0.5Sp

y=0 y = 0.5Sp

C P

1.0

C P

1.0

0.8

0.8

rt = 0.50

A 0.6

A 0.6

rt = 0.50

rt = 1.0

0.4

rt = 1.0

0.4

0.2

0.2

rt = 0.50

rt = 0.50

0

rt = 1.0

0

0.2

0.4

0.6 C/Sp

0.8

1.0

0

rt = 1.0

0

(a) Slab without edge stiffening

0.2

0.4

0.6 C/Sp

0.8

1.0

(b) Slab with edge stiffening

Note: For rt < 0.5, use refined analysis.



Figure 5.2 Calculation of A (See Clause 5.7.1.6.1.1.)

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Table 5.10 Maximum cantilever moments, My , due to unfactored CL-625 Truck wheel loads (DLA included), kN•m/m



(See Clause 5.7.1.6.1.1.)

Sp , m 1.00 1.50 2.00 2.50 3.00

Unstiffened edge

Stiffened edge

Max. My in kN•m/m

Max. My in kN•m/m

rt = 1.00 41 43 53 60 92

rt = 0.75 43 47 57 65 99

rt = 0.5

rt = 1.00

rt = 0.75

rt = 0.5

44 51 60 70 107

37 34 35 37 70

41 37 39 40 74

45 41 43 43 77

Notes: (1) Values obtained for y = 0, C = Sp – 0.75. (2) rt = t1/t2.

0.30 m P

P

1.8 m t2

t1

–> 0.75 m Sp

S

Figure 5.3 Notation for cantilever moments



(See Table 5.10.)

5.7.1.6.2 Local longitudinal moment in cantilever slabs (main reinforcement parallel to traffic) For longitudinal cantilever spans not longer than 3 m, the maximum intensity of local longitudinal moment, Mx , in kN•m/m, shall be calculated as follows: Mx = PC/F where P

= 87.5 kN wheel load of the CL-W Truck

C

= longitudinal distance of P from the line of transverse support, m

F

= 0.35C + 1.00 (but shall not exceed 2.10 m) The relevant design moment shall be obtained by multiplying Mx by (1 + DLA).

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For longitudinal cantilever spans longer than 3 m, the methods specified in Clause 5.7.1.2.1 shall be used, with the span length, L , being taken as twice the cantilever span. The live loading to be used shall be in accordance with Clause 3.8.4.3(c).

5.7.1.6.3 Transverse moments in cantilever slabs due to railing loads In determining transverse moments in cantilever slabs resulting from the barrier or railing loads specified in Clause 3.8.8.1 and applied in accordance with Clause 12.4.3.5, the method of analysis shall be (a) a refined method in accordance with Clause 5.9; or (b) yield line theory.

5.7.1.7 Transverse bending moments in decks 

5.7.1.7.1 Concrete decks slabs supported on longitudinal girders Concrete deck slabs shall be analyzed for positive and negative bending moments resulting from loads applied on the slabs. The analysis shall consider the bending moments induced in the longitudinal direction that agree with the assumptions used in the analysis of the transverse bending moments. The cantilever portions of concrete deck slabs shall be analyzed for transverse negative bending moments resulting from loads on the cantilever portions of the slabs or horizontal loads on barriers and railings. The cantilever portions of concrete deck slabs may be analyzed using Clause 5.7.1.6. Concrete deck slabs (cantilever portions that are proportioned in accordance with the empirical design method of Clause 8.18.4 for the CL-625 Truck) need not be analyzed for transverse bending moments due to live load. Concrete deck slabs that are supported on longitudinal girders may be analyzed for transverse bending using the simplified elastic method in which the maximum unfactored transverse moment intensity in the portion of the deck slab between the outer girders due to the CL-625 Truck shall be determined as follows: (a) Except for portions of the deck slab within 1 m of a free edge, the deck slab shall be designed for an unfactored transverse live load moment intensity as follows: (i) for simple span deck slabs: (Se + 0.6)P/10 kN•m/m, where Se is the equivalent transverse span in metres, which can be determined from Figure 5.1A for different types of superstructures. P is 87.5 kN, the maximum wheel load of the CL-625 Truck; and (ii) for deck slabs continuous over three or more supports, the maximum bending moment, either positive or negative, shall be assumed to be 80% of that determined for a simple span. These moments shall be increased by the dynamic load allowance for a single axle, as specified in Clause 3.8.4.5.3. (b) The portion of a deck slab within 1 m of a transverse free edge shall be reinforced to twice the level of the transverse reinforcement in the other portions of the deck slab unless equivalent local stiffening by diaphragms is provided in accordance with a requirement in another Section of this Code. (c) The longitudinal moment intensity for distribution of wheel loads to be used with the transverse moment intensity specified in Item (a) shall be taken as 120/(Se0.5)% (but not to exceed 67% of the maximum transverse moment intensity) and shall be applied as a positive moment that produces tension in the bottom portion of the deck slab. The longitudinal reinforcement necessary to resist the longitudinal moment shall be used in the centre half of the span. The percentage may be reduced by 50% in the end quarters of the span.

5.7.1.7.2 Steel grid decks 5.7.1.7.2.1 General Transverse bending moments due to live load in steel grid decks shall be determined as specified in this Clause and Clauses 5.7.1.7.2.2 and 5.7.1.7.2.3. The grid floor shall be designed as continuous. For concrete-filled floors, moments may be determined in accordance with Clause 5.7.1.7.1 using the simplified elastic method for concrete decks.

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The requirements for load distribution specified in Clauses 5.7.1.7.2.2 and 5.7.1.7.2.3 assume that the floor is composed of main elements that span between girders, stringers, or cross-beams, and of secondary elements that are capable of transferring load between the main elements. Reinforcement for secondary elements shall consist of bars or shapes welded to the main steel.

5.7.1.7.2.2 Decks filled with concrete Floors filled with concrete that span perpendicular to the direction of traffic may be analyzed using the elastic method for concrete deck design for load distribution and moment calculation. Floors that span longitudinally shall be designed for longitudinal moments determined by distributing one line of truck wheel loads over a width E = 1.22 + 0.06S 2.1 m, where S is the span in metres. Longitudinal edge beams shall be provided for all cantilevered slabs having main reinforcement parallel to traffic. The beam may consist of a slab section additionally reinforced, a beam integral with and deeper than the slab, or an integral reinforced section of slab and curb or slab and parapet. The unfactored live load moment for the longitudinal edge beam shall equal 0.1PS kN•m for simple spans and 0.08PS kN•m for continuous spans, where S is the span, in metres, between points of support. Transverse cantilevered beams, diaphragms, or substructure locations are considered points of support. P is the maximum wheel load of the CL-625 Truck (87.5 kN), which shall be increased by (1 + DLA). The strength of the composite steel and concrete slab shall be determined using the “transformed area” method.

5.7.1.7.2.3 Open decks A wheel load of one-tenth of the total weight of the CL-625 Truck (62.5 kN), further increased by (1 + DLA), shall be distributed over a length and width equal to the wheel dimensions specified in Clause 3.8.3.2. The strength of the section shall be determined using the moment of inertia method. Edges of open grid steel decks shall be supported by suitable means as required. These supports may be longitudinal, transverse, or both, as required to support all edges properly.

5.7.1.7.3 Transverse laminated wood decking on sawn timber stringers For bridges with sawn timber stringers, the maximum transverse moment intensity, My , due to the CL-625 Truck or to Level 2 or 3 evaluation trucks shall be calculated as follows: My = 2.40 + 0.47Ls for bridges with one design lane = 2.19 + 0.56Ls for bridges with more than one design lane In these equations, Ls , the stringer span, is in metres and My is in kN•m/m.

5.7.1.7.4 Transverse stress-laminated wood deck-on-girders For bridges with stress-laminated wood decks, the transverse moment in the decking shall be calculated by assuming that a transverse line of wheels is sustained uniformly by a transverse strip of the decking of a width, Dt , measured in the longitudinal direction of the bridge span, with Dt = 0.30 + 0.4S for decks with edge stiffening at the transverse free edges, and in which the flexural rigidity of the stiffening beam is greater than or equal to that of a transverse strip of the decking with a width, measured in the longitudinal direction of the bridge span, of 0.25 m. In this equation Dt and S are in metres and S is the girder spacing. If the stiffening beam is absent or has a flexural rigidity less than specified in this Clause, Dt = 0.30 + 0.14S shall be used.

5.7.1.7.5 Transverse nail-laminated wood deck-on-girders Transverse bending moments due to live load on transverse nail-laminated wood deck-on-girders shall be determined by distributing a wheel load over a width of 0.4 m plus the thickness of the wearing surface.

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5.7.1.7.6 Transverse wood plank deck-on-girders Transverse bending moments due to live load in wood plank decks shall be determined using the equivalent strip method and distributing a wheel load over the width of a plank or 0.25 m, whichever is larger.

5.7.1.8 Transverse vertical shear 5.7.1.8.1 Transverse vertical shear in shear-connected beam bridges The maximum intensity of transverse vertical shear, Vy , in kN/m, shall be assumed to occur when there is only one design vehicle on the bridge. The following simplified method may be used for shear-connected beam bridges: (a) The value of β is calculated as follows:

⎡B ⎤ ⎡ D ⎤ b = π⎢ ⎥⎢ x ⎥ ⎣ L ⎦ ⎢⎣ Dxy ⎥⎦

0.5

(b) In accordance with Figure 5.4, the value of transverse vertical shear intensity, Vy , in kN/m is calculated as follows: β=

Vy = kW where k

= applicable value obtained from Figure 5.4, m–1

W

= heaviest axle load of the design vehicle, kN

Linear interpolation for this intensity is to be used for widths falling between the widths specified in Figure 5.4. (c) The intensity of transverse vertical shear obtained in accordance with Item (b) shall be multiplied by (1 + DLA) to obtain the design intensity of transverse vertical shear, where DLA is the applicable dynamic load allowance for a single vehicle, as specified in Clause 3.8.4.5.

5.7.1.8.2 Transverse vertical shear in transverse wood plank deck-on-girders The transverse vertical shear due to live load on wood plank decks shall be determined using the equivalent strip method and distributing a wheel load over the width of a plank or 0.25 m, whichever is larger.

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1.5

β = 0.2 β = 0.5

1.0

β = 1.0 β = 1.5 β = 2.0

k, m –1

0.5

0

0

10

20 30 Span, m

40

50

(a) B = 7.5 m 1.5

β = 0.2 β = 0.5

1.0

β = 1.0 β = 1.5 β = 2.0

k, m –1

0.5

0

0

10

20

30

40

50

Span, m

(b) B = 10.0 m

Figure 5.4 Values of k for calculating transverse vertical shear in shear-connected beam bridges (See Clause 5.7.1.8.1.) (Continued)

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1.5

β = 0.2 β = 0.5 β = 1.0 β = 1.5

1.0

β = 2.0

k, m –1

0.5

0

0

10

20 30 Span, m

40

50

(c) B = 12.5 m

1.5

β = 0.2 β = 0.5 β = 1.0 β = 1.5

1.0 k,

β = 2.0

m –1

0.5

0

0

10

20

30

40

50

Span, m

(d) B = 15.0 m

Figure 5.4 (Concluded)

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5.7.1.9 Analysis of stringers in truss and arch bridges In analyzing the stringers in truss and arch bridges, the portion of the bridge between adjacent floor beams may be analyzed using the methods specified in Clause 5.6.1.2 for dead load and Clauses 5.7.1.2 and 5.7.1.4 for live load; in both cases, the distance between the adjacent floor beams shall be taken as L, which, if less than 3.0 m, shall be taken as 3.0 m. When stringers are designed with continuity at the floor beam supports, the flexibility of the floor beams shall be considered.

5.7.1.10 Analysis of floor beams in truss and arch bridges A live load situated between two floor beams shall be divided between the two beams by simple static division, using the lever principle, without any dispersion of the load along the beams. The line of the lever shall be perpendicular to the floor beams.

5.7.1.11 Analysis of orthotropic steel decks 5.7.1.11.1 General Force effects in orthotropic decks may be determined by elastic methods of analysis, e.g., equivalent grillage, or by finite strip or finite element methods as specified in Clause 5.9. In lieu of a more precise analysis, the use of the approximate methods of analysis, as specified in Clauses 5.7.1.11.3 to 5.7.1.11.5, shall be permitted.

5.7.1.11.2 Wheel load distribution A 45° distribution in all directions of the tire pressure calculated in accordance with Clauses 3.8.3.2, 3.8.4.3, and 3.8.4.4 from the surface contact area to the middle of the steel deck plate (including dynamic load allowance for a single axle in accordance with Clause 3.8.4.5) may be assumed.

5.7.1.11.3 Effective width of deck The effective width of deck shall be as specified in Clause 5.8.2.2.

5.7.1.11.4 Approximate analysis of decks with open ribs The rib may be analyzed as a continuous beam supported by the floor beams. For rib spans not exceeding 4.6 m, the load on one rib due to wheel loads may be determined as the reaction of transversely continuous deck plate on rigid ribs. For rib spans greater than 4.6 m, the effect of rib flexibility on the lateral distribution of wheel loads shall be considered, and for this purpose elastic analysis shall be employed. For rib spans not greater than 3 m, the flexibility of the floor beams shall be considered when force effects are calculated.

5.7.1.11.5 Approximate analysis of decks with closed ribs For the analysis of decks with closed ribs, semi-empirical methods may be used. The load effects on a closed rib with the span not greater than 6.1 m may be calculated from wheel loads placed over one rib only, with the effects of the adjacent transversely located wheel loads disregarded.

5.7.2 Refined methods of analysis For short- and medium-span bridges where the simplified methods specified in Clause 5.7.1 are not applicable, a refined method of analysis in accordance with Clause 5.9 shall be used. In cases where the requirements of Clause 5.7.1 are met, a refined method of analysis may nevertheless be used. For long-span bridges, a refined method in accordance with Clause 5.10 shall be used.

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5.8 Idealization of structure and interpretation of results 5.8.1 General In the analysis, the structure, boundary conditions, and loading shall be idealized in such a way that the total idealization represents realistically the properties of the actual structure, the actual boundary conditions, and the actual dead and applied loads. The method of idealizing the structure specified in Clause A5.2.1 may be used. In applying the results of the analysis to the actual structure, the structural responses carried by any component of the mathematical model shall be deemed to be carried by the portion or portions of the actual structure for which the given component is the analogue.

5.8.2 Effective flange widths for bending 5.8.2.1 Concrete slab-on-girders In the calculation of bending resistances and bending stresses in slab-on-girder bridges and box girder bridges with a concrete slab, a reduced cross-section shall be used. The reduced cross-section shall comprise a left-hand overhang, a central portion, and a right-hand overhang. The overhang, be , shall be determined as follows: 3

L ⎤ ⎡ be / b = 1− ⎢1− for L / b ≤ 15 15 b ⎥⎦ ⎣ = 1 for L / b > 15 where be

= dimension shown in Figure 5.5 for the applicable type of bridge cross-section

b

= the dimension shown in Figure 5.5 for the applicable type of bridge cross-section

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be

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be

b

be

be

2b

be

b

2b Steel or concrete

Steel or concrete be

be

be

be be

b

2b

be

be

b be

b

45° Steel or concrete

be

2b

2b be

2b

Figure 5.5 be and b for various cross-sections (See Clause 5.8.2.1.)

5.8.2.2 Orthotropic steel decks 5.8.2.2.1 Longitudinal ribs The effective width of the deck acting as the top flange of one longitudinal stiffener or one rib shall be determined from Table 5.11.

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Table 5.11 Effective deck plate width for a longitudinal rib (See Clause 5.8.2.2.1.) ao

a

ao + eo

a

Effective width = ao

e

a

e

Effective width = ao + eo

Rib section properties for calculation of deck rigidity and flexural effects due to dead load

ao = a

ao + eo = a + e

Rib section properties for calculation of flexural effects due to wheel loads

ao = 1.1a

ao + eo = 1.3(a + e)

5.8.2.2.2 Longitudinal girders and transverse beams The effective width of the deck acting as the top flange of a longitudinal superstructure component or transverse beam may be determined using an accepted method of analysis or may be taken as shown in Figure 5.6. The effective span, L, shown as 1 and 2 in Figure 5.6 shall be taken as the actual span for simple spans and as the distance between points of dead load contraflexure for continuous spans.

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Bp

t

As = total area of stiffeners in width B 0.5Ψ B

0.85ΨpBp

Points of inflection

Bp

B

0.5Ψ B

2

Uniform load

1

0.85ΨpBp Actual stress distribution

Maximum stress

1  1 /4

 1 /4 Inflection point or simple support

Effective width of flange 1.0 As = 0 Bt =1

1 3

5

4

2

0.8

6

0.6

Ψ or Ψp

C1

C2 2

0.4

If C1 = C2, obtain Ψ as the average of the values of Ψ for  2 = 2C1 and 2 = 2C2

0.2

0

0

5

10

15

20

L/B or L/2Bp



Figure 5.6 Effective width of orthotropic deck (See Clause 5.8.2.2.2.)

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Notes: (1) Curves 1 and 2 apply to the middle half of the positive moment region of beams. (2) Curves 3 and 4 apply to areas in positive moment regions located between the inflection point or simple support and one-quarter of the length of the positive moment region. (3) Curves 5 and 6 apply to negative moment regions. Legend: B = spacing of longitudinal or transverse beams, as applicable, mm Bp

=

l1 , l2 = L = =

ψ ψp

= =

length of the cantilever portion of the transverse beam, mm distances between the points of inflection of the longitudinal or transverse beams, as applicable, mm l1 for positive moment regions of the longitudinal or transverse beams, as applicable l2 for negative moment regions of the longitudinal beams or transverse beams Note: For cantilever portions of transverse beams, L shall be taken as twice the length of the cantilever. effective plate width factor for interior portions of deck between beams effective width factor for exterior or cantilever portions of deck

Figure 5.6 (Concluded) 5.8.3 Idealization for analysis For the purposes of analysis, the stiffness properties for concrete and composite members shall be based on uncracked sections or on cracked and/or uncracked sections consistent with the anticipated behaviour.

5.9 Refined methods of analysis for short- and medium-span bridges 5.9.1 Selection of methods of analysis The refined methods of analysis for short- and medium-span bridges are as follows: (a) grillage analogy; (b) orthotropic plate theory; (c) finite element; (d) finite strip; (e) folded plate; and (f) semi-continuum. Unless specified elsewhere in this Code or Approved, the method or methods of analysis may be selected from Table 5.12. Other methods may be used if they are capable of providing a level of accuracy comparable to that of the methods specified in Items (a) to (f).

5.9.2 Specific applications Influence surfaces may be used to evaluate relevant responses in bridge superstructures if they are developed from the refined methods specified in Clause 5.9.1 or from model analysis in accordance with Clause 5.9.3. The use of influence surfaces developed using other methods shall require Approval.

5.9.3 Model analysis The use of model analysis (which involves testing a physical model of the whole or part of a bridge) shall be acceptable as an alternative or addition to other methods of analysis permitted in this Section. The model analysis and the interpretation of the results for the purpose of design shall require Approval.

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Table 5.12 Selection of methods of analysis (See Clause 5.9.4.) Bridge type(s) (see Clause 5.1) for which the method is appropriate

Limitations on applicability

Simplified method specified in Clause 5.6.1.2 for dead load

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Single cell Box girder — Multi-cell Box girder — Multi-spine

Elements of the structure shall meet the requirements of Clause 5.6.1.1

Simplified method specified in Clauses 5.7.1.2, 5.7.1.4, 5.7.1.6, and 5.7.1.7 for live load

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams

Structure shall meet the requirements of Clause 5.7.1.1

Simplified method specified in Clauses 5.7.1.3 and 5.7.1.5 for live load

Box girder — Multi-spine

Structure shall meet the requirements of Clause 5.7.1.1

Grillage analogy

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Multi-cell Box girder — Multi-spine Orthotropic decks

—

Orthotropic plate theory

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Multi-spine Orthotropic decks

Structure shall meet the requirements of Clause 5.7.1.1

Method of analysis

(Continued)

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Table 5.12 (Concluded) Method of analysis

Bridge type(s) (see Clause 5.1) for which the method is appropriate

Limitations on applicability

Finite element

All bridge types

For shear-connected beam bridges, it is possible that special elements with zero transverse rigidity will be necessary

Finite strip

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Single cell Box girder — Multi-cell Box girder — Multi-spine Orthotropic decks Cable stayed Suspension

The support conditions are closely equivalent to line support at the ends of the bridge. In the case of multi-span bridges, isolated column supports shall be permitted. For shear-connected beam bridges, it is possible that special elements with zero transverse rigidity will be necessary.

Folded plate

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Single cell Box girder — Multi-cell Box girder — Multi-spine Orthotropic decks

Not applicable to bridges with (a) a skew parameter greater than that permitted by Clause 5.6.1.1; or (b) support conditions other than those permitted by Clause 5.6.1.1. For shear-connected beam bridges, it is possible that special elements with zero transverse rigidity will be necessary.

Semi-continuum

Slab Voided slab Slab-on-girder Shear-connected beam Floor systems of truss, arch, or rigid frame and integral abutment Bridges incorporating longitudinal wood beams Box girder — Multi-spine Orthotropic decks

Structures shall meet the requirements of Clause 5.7.1.1

Conventional methods of analysis for truss, arch, or rigid frame and integral abutment

Trusses, arches, and rigid frames and integral abutment, as applicable

—

Influence surface

All bridge types

In accordance with Clause 5.9.2

Model analysis

All bridge types

In accordance with Clause 5.9.3

Other methods

All bridge types

Require Approval

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5.10 Long-span bridges 5.10.1 General In the analysis of cable-stayed bridges, suspension bridges, and long-span arches, the deflected shape of the structure shall be used in the formulation of equilibrium. For other types of long-span bridges, the analysis may be based on typical assumptions associated with small-deflection, linear-elastic structures. The elastic method used shall be capable of determining all essential structural responses.

5.10.2 Cable-stayed bridges Spatial or planar structural analysis may be used to determine the distribution of force effects in the components of a cable-stayed bridge if the tower geometry, the number of planes of stays, and the torsional stiffness of the deck superstructure are considered. Cable-stayed bridges shall be investigated for (a) non-linear effects that could result from the change in cable sag at all limit states; (b) deformation of the deck superstructure at all limit states; and (c) material non-linearity at the ultimate limit states. The change in force effects due to deflection may be investigated using any method that satisfies large-deflection theory and accounts for the change in orientation at the ends of the cable stays. Cable-stayed bridges shall be investigated for the effects of the loss of any cable stay in order to ensure the integrity of the structure in the event of such a loss. Cable stays shall be designed to be easily replaceable.

5.10.3 Suspension bridges For suspension bridges, force effects shall be analyzed using the large-deflection theory for vertical, torsional, and lateral loads. Linear and elastic material properties may be assumed; however, the non-linear geometrical relationship between force and deformation shall be accounted for. The effects of wind loads shall be analyzed, taking into consideration the tension stiffening of the cables.

5.11 Dynamic analysis 5.11.1 General requirements of structural analysis 5.11.1.1 General For analysis of the dynamic behaviour of bridges, the stiffness, mass, and damping characteristics of the structural components shall be modelled. The minimum number of degrees of freedom included in the analysis shall be based on the number of natural frequencies to be obtained and the reliability of the assumed mode shapes. The model shall be compatible with the accuracy of the solution method. Dynamic models shall include relevant aspects of the structure and the excitation. The relevant aspects of the structure may include distribution of mass, distribution of stiffness, and damping characteristics. The relevant aspects of excitation may include frequency of the forcing function, duration of application, and direction of application.

5.11.1.2 Distribution of masses The modelling of mass shall be consistent with the number of mode shapes used in the analysis.

5.11.1.3 Stiffness The stiffnesses of the elements of the model shall be consistent with the corresponding portions of the bridge being modelled.

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5.11.1.4 Damping Equivalent viscous damping may be used to represent energy dissipation.

5.11.1.5 Natural frequencies For the purpose of Clause 5.11.2, and unless otherwise specified by the Regulatory Authority, elastic undamped natural modes and frequencies of vibration shall be used. For the purpose of Clause 5.11.4 and Section 4, all relevant damped modes and frequencies shall be considered.

5.11.2 Elastic dynamic responses 5.11.2.1 Vehicle-induced vibrations Vehicle-induced vibrations shall be accounted for by applying a dynamic load allowance, i.e., an equivalent static load equal to a fraction of the applied live load. The dynamic load allowance shall be as specified in Clause 3.8.4.5.

5.11.2.2 Wind-induced vibrations In accordance with Clauses 3.10.4.1 and 3.10.4.2, wind-sensitive structures shall be analyzed for dynamic effects such as buffeting by turbulent or gusting winds and unstable wind–structure interaction such as vortex shedding, galloping, and flutter. Slender or torsionally flexible structures shall be analyzed for lateral buckling, excessive thrust, and divergence. Oscillatory deformations under wind that could lead to excessive stress levels, structural fatigue, and user inconvenience shall be avoided. Bridge decks, cable stays, and hanger cables shall be protected against excessive vortex and against oscillations induced by wind and rain. Where practical, the employment of dampers shall be considered to control excessive dynamic responses. Where dampers or shape modification are not practical, the structural system shall be changed to achieve such control.

5.11.3 Inelastic-dynamic responses 5.11.3.1 General Energy dissipation by one or more of the following mechanisms during a major earthquake or ship collision may be taken into account: (a) elastic or inelastic deformation of the object that could collide with the structure; (b) inelastic deformation of the structure and its attachments; (c) permanent displacements of the masses of the structure and its attachments; and (d) inelastic deformation of special-purpose mechanical energy dissipaters.

5.11.3.2 Plastic hinges and yield lines For the purpose of analysis, energy absorbed by inelastic deformation in a structural component may be assumed to be concentrated in plastic hinges and yield lines. The location of these sections may be established by successive approximation to obtain a lower bound solution for the energy absorbed. For these sections, moment-rotation hysteresis curves may be determined using verified analytic material models.

5.11.4 Analysis for collision loads Where permitted by Section 3, dynamic analysis of ship collision may be replaced by an equivalent static elastic analysis. Where an inelastic analysis is specified, the effect of other loads that could be present shall be considered.

5.11.5 Seismic analysis The minimum analysis requirements for seismic effects shall be as specified in Clauses 4.4.5, 4.5, and 4.11.5. May 2010 (Replaces p. 211, November 2006)

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5.12 Stability and magnification of force effects 5.12.1 General Stability effects are divided into two categories: member stability and structural stability. The stability of individual members, of the components of structural assemblies, and of structural systems shall be considered in the analysis. Stability analyses of structural assemblies and individual members shall be performed as specified in the clauses of Sections 8 to 10 and 16 that apply to the material(s) used for the members.

5.12.2 Member stability analysis for magnification of member bending moments Member stability analysis shall be performed in order to account for (a) the interaction between axial compression forces and bending moments or out-of-straightness of a member; and (b) the possible increase of the bending moment magnitude between the two ends of a member. Each member shall be considered individually. 

5.12.3 Structural stability analysis for lateral sway Structural stability analysis shall be performed to account for gravity loads undergoing lateral sway arising from horizontal loads or out-of-plumbness of the structure. This structural analysis shall encompass all members or structural components resisting the sway. In lieu of a more refined second-order analysis, the following equations may be used: Me = Mns + s Ms where Me

= moment at the end of an individual compression member

Mns

= moment at the end of a compression member due to loads that cause no appreciable sway, calculated using first-order elastic analysis

Ms

= moment at the end of a compression member due to loads that cause appreciable sway, calculated using first-order elastic analysis

s

= moment magnification factor accounting for second-order effects of vertical load acting on a structure in a laterally displaced configuration

Second-order effects may be neglected if s  1.05. The moment magnification factor, s , may be calculated by one of the two following methods: Method I

1

ds = 1−

∑ Pf

fm ∑ Pc

where Pf

= summation of all vertical loads on the sway-resisting columns

Pc

= summation of all column-buckling loads in the sway-resisting system

m

= 0.75 for concrete elements = 1.0 for structural steel elements

Pc shall be calculated similarly to Pc in Clause 8.8.5.3 for concrete elements and to Ce in Clause 10.9.4.2 for steel elements.

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Method II

1

ds = 1−

∑ Pf fm ∑ (Ssh )

where Pf

= summation of all vertical loads on the sway-resisting columns

Ss

= lateral stiffness of sway-resisting element

h

= height of associated sway-resisting element

m

= 0.75 for concrete elements = 1.0 for structural steel elements

5.12.4 Structural stability analysis for assemblies of individual members The structural stability of an assembly of individual members shall be considered for the condition of the buckling of such an assembly acting as a whole.

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Annex A5.1 (normative) Factors affecting structural response Note: This Annex is a mandatory part of this Code.

A5.1.1 General The factors affecting structural response are specified in this Annex. The method of analysis chosen shall be capable of evaluating behaviour affected by these factors.

A5.1.2 Continuity of spans When the simplified methods specified in Clauses 5.7.1.2 to 5.7.1.5 are to be used for a multi-span bridge, the effect of continuity may be accounted for, provided that the ends of the bridge are free of externally applied restraint against rotation, by taking the value of L for obtaining F as follows: (a) for positive moments in an exterior span: 80% of the distance between the external support and the internal support; (b) for positive moments in an interior span: 60% of the distance between the internal supports; and (c) for negative moments in the region of an internal support: 25% of the sum of the spans on either side of the support. The positive moment and negative moment regions (only for the purpose of obtaining the value of F ) will then be as shown in Figure A5.1.1. Unless specified elsewhere in this Section, points of inflexion shall not be assumed to occur at the positions shown in Figure A5.1.1 for any purpose other than calculating F. A value of 3.0 m shall be assumed for L if it is found to be less than 3.0 m. M– calculation

0.75L1

0.25(L1 + L2)

0.5L2

0.25(L2 + L3)

0.75L3

M+ calculation

0.8L1

0.2(L1 + L2)

0.6L2

0.2(L2 + L3)

0.8L3

L1

L2

L3

Figure A5.1.1 Assumed points of inflexion under dead loads (See Clause A5.1.2.)

A5.1.3 Plan geometry A5.1.3.1 Shallow superstructures on skew spans 

A5.1.3.1.1

If, for solid and voided slab bridges, the skew parameter  =  tan  /L does not exceed 1/6, and, for slab-on-girder bridges, the skew parameter  = S tan  /L does not exceed 1/18, the angle of skew may be October 2011 (Replaces p. 213, November 2006)

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ignored for the calculation of longitudinal moment and shears if the analysis is carried out for a right span that is equal to the skew span of the actual structure. Note: S is the girder spacing, L is the span, and B is the bridge width.

A5.1.3.1.2 A5.1.3.1.2.1 For values of the skew parameter greater than those specified in Clause A5.1.3.1.1, the effects of longitudinal and transverse torsion under live and dead loads and prestressing forces shall be considered, except that slab-on-girder bridges satisfying all of the applicable conditions listed in Clause 5.7.1.1 may be analyzed using the simplified methods of Clause 5.7.1, supplemented as specified in Clause A5.1.3.1.2.2.

A5.1.3.1.2.2 For slab-on-girder bridges with skew, a simplified method of analysis for longitudinal bending moment may be used in the absence of a more refined method, i.e., the corresponding bridge without skew, using the skew span, may be analyzed for longitudinal bending moment in accordance with Clauses 5.7.1.2.1 and 5.7.1.2.2. The bending moments thus obtained may be used for design without modification.

A5.1.3.1.3 For the calculation of longitudinal vertical shear in slab-on-girder bridges with skew, the increase of shear forces near an obtuse corner as compared to skewless bridges shall be taken into account in accordance with a suitable method.

A5.1.3.2 Bridges curved in plan For both live and dead loads, longitudinal twisting moments and the associated effects of torsional and distortional warping shall be considered. If L2/BR for a bridge as shown in Figure A5.1.2 is not greater than 0.5, the bridge may be treated as straight for the calculation of values in simplified methods of analysis if there are at least two intermediate diaphragms per span. L

B R

Figure A5.1.2 Bridges curved in plan (See Clause A5.1.3.2.)

A5.1.3.3 Other plan geometries When a bridge superstructure with a plan geometry that is not rectangular, skewed, or curved is analyzed, the method of analysis shall be capable of deriving all relevant structural responses and shall be compatible with the requirements specified in Clauses A5.1.3.1 and A5.1.3.2.

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A5.1.4 Transverse variation of longitudinal section A slab that is tapered in the vicinity of its free edges for a distance of up to 2.5 m may be regarded as being of constant thickness if the total width of the slab is conceptually reduced so as to have the cross-sectional area shown in Figure A5.1.3. < – 2.5 m

< – 2.5 m

< – 2.5 m

Actual structure Same area

Same area

Same area

Equivalent structure Equivalent width

Equivalent width

Equivalent width

Figure A5.1.3 Idealization of cross-section with a varying thickness (See Clause A5.1.4.)

A5.1.5 Diaphragms and cross-frames For bridges of the shallow superstructure type, the effect on the structural responses of diaphragms and cross-frames between supports may be ignored. In the case of box girders, all diaphragms and cross-frames shall be taken into consideration if the number of diaphragms and cross-frames is less than the minimum number required in Table 5.1 when the analysis is based on a method other than the simplified method specified in Clauses 5.6 and 5.7.

A5.1.6 Wind bracing Engineering judgment shall be used to decide whether the forces in the wind bracing arising from its acting integrally with the rest of the structure need be considered; if so, the analysis shall be able to predict these forces.

A5.1.7 Interaction of floor system and its support system In truss bridges and arch bridges where the floor system is connected to the trusses or arches in such a way that at least a part of the floor system acts integrally with the trusses or arches, the effective contribution from the floor system may be included.

A5.1.8 Barrier and parapet walls In cases where the bridge incorporates barrier or parapet walls that are structurally integral with the bridge, (a) the effect of the barrier or parapet walls shall be ignored in calculating the distribution of loads for ultimate limit states and serviceability limit states; November 2006

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(b) the barrier or parapet walls may be included in the bridge cross-section in calculating the distribution of loads for the FLS and superstructure vibration; and (c) the beneficial effect of barrier walls may be included in calculating the distribution of loads for the ULS of deck slabs only.

A5.1.9 Support conditions other than line support In cases where the support condition includes isolated supports or generates an irregular pattern of support forces, the analysis shall be capable of assessing the local behaviour arising from the support condition.

A5.1.10 Movement of supports and supports for continuous and skew spans The methods of analysis shall take into account the anticipated support conditions in new bridges and the actual support conditions in existing bridges, either directly or through subsequent adjustments to the results of the analysis. In continuous or skew structures, the analysis shall be capable of taking into account differential settlement.

A5.1.11 Temperature effects Stresses due to changes in the mean temperature of the bridge or to temperature gradients shall be assessed in accordance with Section 3.

A5.1.12 Creep and shrinkage The structural response of a bridge superstructure due to the creep and shrinkage effects of concrete shall be provided for in accordance with Sections 3 and 8.

A5.1.13 Secondary force effects and elastic shortening The influence of secondary force effects and elastic shortening shall be considered. Elastic methods of analysis shall be used for this purpose.

A5.1.14 Construction sequence Due account shall be taken of the change in nature of the structural system and of changes in material properties that occur during the construction sequence. The behaviour at any stage of the construction sequence shall be analyzed using elastic methods of analysis.

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Annex A5.2 (informative) Two-dimensional analysis Note: This Annex is not a mandatory part of this Code.



A5.2.1 Two-dimensional analysis of steel, aluminum, or concrete superstructures



A5.2.1.1 For two-dimensional analysis, shallow steel, aluminum, or concrete superstructures may be idealized as grillages or orthotropic plates.

A5.2.1.2 For considering the flexural behaviour of the bridge types described in Clause A5.2.1.1 using two-dimensional mathematical models, the following parameters are necessary: (a) Parameters that depend on the material: E = modulus of elasticity

 = Poisson’s ratio (taken as 0.15 for concrete and 0.30 for steel) G = shear modulus = E/2(1 +  ) n = modular ratio, Es / E c (b) Parameters that depend on the cross-section: iL = longitudinal moment of inertia per unit width jL = longitudinal torsional inertia per unit width iT = transverse moment of inertia per unit length jT = transverse torsional inertia per unit length sv = shear area per unit length (needed only for slabs with rectangular voids)

A5.2.1.3 The properties required for analysis as grillage or orthotropic plate may be calculated as specified in Table A5.2.1 and the values of the parameters may be calculated as specified in Table A5.2.2. For both reinforced concrete and prestressed concrete, the uncracked section should be used in calculating these parameters. The factors F1 and F2 indicated in Table A5.2.2 for voided slabs may be obtained from Figure A5.2.1. In other cases, the torsional inertia of a section may be calculated by dividing the section into a number of rectangles and adding the torsional inertias of all rectangles. The torsional inertia of a single rectangle with sides a and b may be taken to be J = Kab3, where a is the longer and b the shorter of the two sides of the rectangle and K is a constant depending on the ratio of a / b , which can be interpolated from Table A5.2.3.

A5.2.1.4 In the absence of a more detailed analysis, the equivalent areas for in-plane analysis of slabs with circular voids may be taken as follows: (a) Ax = the equivalent area of the transverse section, per unit width

=t −

π (tv ) 4S

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(b) Ay = the equivalent area of the longitudinal section, per unit length

t ⎤ ⎡ S − tv ⎤ ⎤ ⎡ ⎡ ⎡t ⎤ ⎡ t ⎤ = t ⎢1− 0.5 ⎢ v ⎥ ⎢1+ v ⎥ + 0.1⎢1.7 − v ⎥ ⎢ t t t ⎦ ⎣ t ⎥⎦ ⎥⎦ ⎣ ⎦ ⎣ ⎦⎣ ⎣

Table A5.2.1 Properties of idealized orthotropic plate or grillage (See Clause A5.2.1.3.)

Longitudinal direction

Transverse direction

Properties to define a two-dimensional orthotropic plate

Grillage beam properties to define a two-dimensional orthogonal grillage

Dx = EiL

Moment of inertia, Ix = i L × (longitudinal grillage beam spacing)

Dxy = GjL*

Torsional inertia, Jx = jL × (longitudinal grillage beam spacing)

D1 =  × (lesser of Dx or Dy)

No equivalent to D1

Dy = EiT

Moment of inertia, Iy = i T × (transverse grillage beam spacing)

Dyx = GjT*

Torsional inertia, Jy = jT × (transverse grillage beam spacing)

D2 = D1

No equivalent to D2

Sy = Gsv†

Transverse shear area = sv × (transverse grillage beam spacing)

*There is a lack of consistency in the application of this value in various analyses. When the analysis uses the following expression to calculate of Mxy , the values of Dxy and Dyx are calculated as specified in this Table:

∂ 2w ∂xy However, when the following expression for calculating Mxy is used, the values of Dxy and Dyx are taken as half those specified in this Table: Mxy = Dxy

∂ 2w ∂xy For grillage properties, the expressions specified in this Table for torsional inertia are always correct as stated. †Required only for voided slabs with rectangular voids. Mxy = 2Dxy

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Table A5.2.2 Expressions for structural parameters (See Clause A5.2.1.3.) Structural parameters

Bridge type and transverse section

iT

iL

Slab

(

t3

12 1− v 2 t

Non-composite slab-on-girder

)

t 3 Ixt + 12 S where Ixt = transformed moment of inertia of the girder about its own x-axis

S

Composite slab-on-girder

Ix S where Ix = the combined transformed moment of inertia of slab portion located in width S

S S/2 S/2

Voided slab with rectangular voids

t 3 − tv3 12

(

t3

12 1− v 2

(

t3

12 1− v 2

(

t3

12 1− v 2

)

)

)

t 3 − tv3 12

jL

jT

sv

t3 6

t3 6

May be ignored

t3 6

t3 6

May be ignored

t3 J t3 + 6 S 6 where J = transformed torsional inertia of the girder multiplied by ng = 0.88n for steel portions

May be ignored

2A12 ds B∑ t

*

t

t1 t3

tv

Median line

t

Median line

t

 t2

2A22 ds L∑ t

L

B

S

Area A1

Voided slab with circular voids

t 3 πtv4 − 12 64S

tv t

F1t 3 12 (F1 from Figure A5.2.1)

Area A2

Intermediate webs ignored

Intermediate diaphragm, if any, ignored

F2t 3 6 (F2 from Figure A5.2.1)

F2t 3 6 (F2 from Figure A5.2.1)

May be ignored

S

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Table A5.2.2 (Concluded) Structural parameters

Bridge type and transverse section

iL

Multi-spine girder

iT

Ix S where Ix = the combined transformed moment of inertia of slab portion located in width S

Area Ao enclosed by median line

S



(

t3

12 1− v 2

)

jL

jT

sv

4A 20 ds S∑ ngt

t3 6

May be ignored for slab between spines. See note (*) for portion within spine. The stiffness of internal braces in spines may be included.

for the portion where of the deck ng = 1.0 for between the concrete spines. The portions value of iT for = 0.88n for steel the portion of portions the deck included in the spine is calculated by considering the total transverse stiffness of the spine, including that of the bracing and diaphragms within the box.

⎡ ⎤ 3 ⎥ ⎡ t13 + t23 ⎤ E ⎢ t S 3 * sv = ⎢ ⎥ for voided slabs with rectangular voids. ⎢ 2 ⎥ ⎣ S ⎦ G ⎢ St33 + t13 + t23 ⎡ t + tv ⎤ ⎥ ⎢⎣ 2 ⎥⎦ ⎥ ⎢⎣ ⎦ Note: All parameters are in terms of deck slab concrete units.

(

)

Table A5.2.3 Torsional constant, K, for rectangular sections where a  b (See Clause A5.2.1.3 and Table A5.2.4.) a/b

1

1.2

1.5

2.0

2.5

3.0

4.0

5.0

10.0

420

K

0.141

0.166

0.196

0.229

0.249

0.263

0.281

0.291

0.312

0.333

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tv

t

S

1.0 0.50 0.60 0.70 t /t 0.75 v 0.80 0.85

0.9 0.8 F1 0.7 0.6 0.5 0.4 0.4

0.5

0.6

0.7

0.8

tv /S

Coefficients for Dy

1.0

0.50 0.60 0.70 t /t 0.75 v 0.80 0.85

0.9 0.8 F2 0.7 0.6 0.5 0.4 0.4

0.5

0.6

0.7

0.8

tv /S

Coefficients for Dxy

Figure A5.2.1 Modification factors for voided slabs (See Clause A5.2.1.3 and Table A5.2.2.)

A5.2.2 Two-dimensional analysis of wood floor systems The six structural parameters needed to idealize a wood floor system for two-dimensional analysis may be calculated as specified in Table A5.2.4. The footnote to Table A5.2.4 applies to the calculation of Dxy . In the absence of actual material properties, a value of 9600 MPa for EL needs to be employed for load distribution analysis of wood floor systems. The effective values of ET and GLT need to be 0.015EL and 0.030EL , respectively. ET is the modulus of elasticity in the principal direction L shown in Figure A5.2.2 and GLT is the shear modulus in the LT plane. For analysis of elastic shortening due to load perpendicular to the grain, ET needs to be taken as 0.05EL in the absence of actual properties.

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Table A5.2.4 Calculation of structural parameters for bridges incorporating wood beams (See Clause A5.2.2.) Structural parameters Bridge type and transverse section

Dx

Dy

Dxy

Dyx

D1 = D2

Transverse laminated wood decks on longitudinal wood beams

EL bt23 12S

ELt13 12

GLT Kt2b3 * S

0.0

0.0

EsI S

ELt13 12

0.0

0.0

0.0

ELt 3 12

ET t 3 12

GLT t 3 6

GLT t 3 6

0.0

Ec I where I = combined moment of inertia of a unit width of concrete and wood using a modular ratio of Ec /EL

Ec t13 12

Gc t13 6

Gc t13 6

ν Dy

t1 t2 b S Transverse laminated decks on longitudinal steel beams

where I = moment of inertia of a girder in steel units

t1 S Glue-laminated and transversely laminated prestressed decks t

Composite concrete slabs on longitudinally laminated wood decks

t1 t2

*K is obtained from Table A5.2.3.

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T

R L

Figure A5.2.2 Principal directions in wood specimen (See Clause A5.2.2.)

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Section 6 — Foundations 6.1 6.2 6.3 6.3.1 6.3.2 6.4 6.4.1 6.4.2 6.4.3 6.4.4 6.4.5 6.4.6 6.5 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.6 6.6.1 6.6.2 6.6.3 6.7 6.7.1 6.7.2 6.7.3 6.7.4 6.7.5 6.8 6.8.1 6.8.2 6.8.3 6.8.4 6.8.5 6.8.6 6.8.7 6.8.8 6.8.9 6.8.10 6.9 6.9.1 6.9.2 6.9.3 6.9.4 6.9.5 6.9.6 6.10 6.10.1 6.10.2 6.10.3

Scope 227 Definitions 227 Abbreviations and symbols 229 Abbreviations 229 Symbols 229 Design requirements 230 Limit states 230 Effects on surroundings 231 Effects on structure 231 Components 231 Consultation 231 Inspection and quality control 231 Geotechnical investigation 231 General 231 Investigation procedures 232 Geotechnical parameters 232 Shallow foundations 232 Deep foundations 232 Report 232 Resistance and deformation 233 General 233 Ultimate limit state 233 Serviceability limit state 234 Shallow foundations 235 General 235 Calculated geotechnical resistance at ULS 235 Pressure distribution 237 Effect of load inclination 238 Factored geotechnical horizontal resistance 239 Deep foundations 240 General 240 Selection of deep foundation units 240 Vertical load transfer 240 Downdrag 240 Factored geotechnical axial resistance 240 Group effects — Vertical loads 241 Factored geotechnical lateral resistance 241 Structural resistance 242 Embedment and spacing 242 Pile shoes and splices 243 Lateral and vertical pressures 243 General 243 Lateral pressures 243 Compaction surcharge 244 Effects of loads 245 Surcharge 245 Wheel load distribution through fill 245 Ground anchors 246 Application 246 Design 246 Materials and installation 246

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6.10.4 6.11 6.11.1 6.11.2 6.11.3 6.11.4 6.12 6.12.1 6.12.2 6.12.3 6.13 6.13.1 6.13.2

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Anchor testing 247 Sheet pile structures 247 Application 247 Design 247 Ties and anchors 248 Cellular sheet pile structures 248 MSE structures 248 Application 248 Design 248 Backfill 249 Pole foundations 249 Application 249 Design 249

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Canadian Highway Bridge Design Code

Section 6 Foundations 6.1 Scope This Section specifies minimum requirements for the design of foundations and the estimation of earth pressures on retaining structures, including requirements pertaining to geotechnical investigations and design reports. This Section does not apply to buried structures that fall within the scope of Section 7 or to the design of structures in permafrost, and is not mandatory for the design of temporary structures. Note: See Figure A3.1.5 for a permafrost region map of Canada.

6.2 Definitions The following definitions apply in this Section: Active pressure — the lateral earth pressure exerted on a retaining structure when it is able to move away from the backfill by an amount sufficient to mobilize the soil strength fully. Assessed value — a value determined through assessment. Assessment — the estimation of resistance and deformation values for a site by reference to values established for other sites known to have similar stratigraphy. At-rest pressure — the lateral earth pressure within soil before it is displaced or excavated. Backfill — the fill retained by a structure, including fill Approved for use as engineered fill, e.g., earth backfill, rock fill, slag, and polystyrene. Backfill also includes retained materials such as in-situ soil or rock. Bearing surface — the contact surface between a foundation or component and the soil or rock on which it bears. Bond length — the portion of a ground anchor that transmits the tendon force to the surrounding soil or rock. Deep foundation — a foundation that transfers load to soil or rock through a combination of toe bearing and shaft resistance at a depth exceeding three times the effective pile width below the surface of backfill or original ground level. The minimum depth for a deep foundation is 3 m below the base of the pile cap. Deformation — the total or differential movement of a foundation, consisting of one or more of settlement, heave, horizontal displacement, and rotation. Double corrosion protection (in relation to ground anchors) — a system of double covering of the tendon to protect against corrosion, normally consisting of encapsulation within a sealed tube that is encased in an outer tube filled with grout. Downdrag load — the load transferred to a deep foundation unit when the surrounding soil settles in relation to it. Dynamic analysis — calculation of the impact force, driving resistance, and energy of a pile by wave propagation theory without the use of field measurements.

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Dynamic test — determination of the resistance, impact force, and developed driving energy of a driven pile by analysis of the measured strain induced by the driving of the pile. Effective height (in relation to a retaining structure) — the overall vertical dimension of the surface over which horizontal earth pressure is assumed to act. Factored geotechnical resistance at ULS — the product of the resistance factor and the ultimate soil or rock resistance. Free-stressing length — the portion of the ground anchor tendon that is free to elongate during stressing. Geotechnical Engineer — an Engineer or foundation engineering specialist responsible for the work related to soil and rock, including site investigation, foundation recommendations, inspection, and quality control. Geotechnical reaction at SLS — the reaction of the soil or rock at the deformation associated with an SLS condition. Geotechnical report — a report prepared by the geotechnical Engineer to satisfy the requirements of Clause 6.5. Geotechnical resistance at ULS — the resistance of soil or rock corresponding to a failure mechanism predicted from theoretical analysis using unfactored geotechnical parameters obtained from testing or estimated from assessed values. Ground anchor — a structural component installed in soil or rock to resist loads transferred to it in tension. Ground anchor tendon — an assembly consisting of prestressing steel, a corrosion protection system, and an end anchorage. Groundwater — a free body of water in the ground. Artesian groundwater — groundwater, in a confined aquifer, under pressure that results in its hydrostatic elevation being higher than the elevation of the top of the confined aquifer at the location of measurement. Groundwater level (groundwater table) — the top surface of a free body of water in the ground. Lockoff load — the load in a ground anchor immediately after the load has been transferred from the jack to the stressing anchorage. Long-term deformation — the time-dependent deformation in soil or rock occurring as a result of consolidation, creep, or both. Passive resistance — the resistance occurring as a result of the movement of a retaining structure, footing, or pile toward backfill, soil, or rock. Pile — a deep foundation unit wholly or partially embedded in the ground and installed by casting-in-place, driving, augering, jetting, or other means. Post-grouting — the pressure grouting of the bond length of a ground anchor after the initial bond grout has set. Relaxation — a reduction in the resistance of a pile over time due to the dissipation of pore water pressure.

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Restrained structure — a wall, abutment, or other retaining structure that cannot move sufficiently to mobilize active earth pressure. Shallow foundation — a foundation in which a footing transfers load directly to the soil- or rock-bearing surface, normally at a depth less than the effective footing width. Short-term deformation — the deformation in soil or rock that occurs on the application of load. Temporary structure — a structure with a service life of less than two years. Transfer load — see Lockoff load. Unrestrained structure — a wall, abutment, or other earth-retaining structure that can move by an amount sufficient to mobilize active pressure in the retained soil.

6.3 Abbreviations and symbols 6.3.1 Abbreviations The following abbreviations apply in this Section: MSE — mechanically stabilized earth SLS — serviceability limit state ULS — ultimate limit state

6.3.2 Symbols The following symbols apply in this Section: A‘

= effective contact area, m2

As‘

= effective peripheral area of the pile shaft within the supporting stratum, m2

At‘

= effective cross-sectional area of the pile tip, m2

B

= width of a shallow foundation, m

B‘

= effective width of a shallow foundation, m

b

= equivalent diameter of a deep foundation unit, taken as the diameter of a round pile or as the face-to-face dimension of an octagonal, hexagonal, or square pile, m

c

= undrained shear strength, kPa

c‘

= effective cohesion, kPa

D

= embedment depth of a shallow foundation, m

eB

= eccentricity of load from the centroid of the footing in the short direction, m

eL

= eccentricity of load from the centroid of the footing in the long direction, m

H

= unfactored horizontal force, kN

Hf

= factored horizontal load, kN

Hri

= factored horizontal shear resistance of the interface between the foundation and the soil, kN

Hrs

= factored horizontal shear resistance of the soil, kN

ic

= inclination factor associated with Nc

iq

= inclination factor associated with Nq

i

= inclination factor associated with N

L

= length of footing or pile, m

L‘

= effective length of footing or pile, m

Nc

= bearing coefficient for cohesion

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

Nq

= bearing coefficient for overburden pressure

N

= bearing coefficient for soil weight

Q

= applied load, kN

q

= applied pressure, kPa

q‘

= effective overburden pressure at the foundation level, kPa

qu

= ultimate geotechnical pressure resistance, kPa

Ru

= ultimate resistance of a deep foundation unit, kN

rs

= ultimate unit shaft resistance within supporting stratum, kPa

rt

= ultimate unit toe resistance, kPa

sc

= shape factor associated with Nc

sq

= shape factor associated with Nq

s

= shape factor associated with N

V

= unfactored vertical force, kN

z

= depth below ground surface, m

 ‘ i  ‘ *

= unit weight, kN/m3

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= effective unit weight, kN/m3 = angle of inclination of force from the vertical, degrees = angle of internal friction, degrees = effective angle of internal friction, degrees = angle of friction at interface between the footing and the soil or rock, degrees

6.4 Design requirements 6.4.1 Limit states 6.4.1.1 General Foundations and retaining structures shall be proportioned to satisfy the requirements of this Section at the SLS and ULS. The design process shall include a consideration of the manner in which a structure and the supporting soil or rock will approach a limit state.

6.4.1.2 Ultimate limit state The ULS conditions to be considered shall include those in which a failure mechanism forms in the soil or rock and those in which loss of static equilibrium or rupture of a portion of the structure occurs because of deformation of the soil or rock. The following shall be considered both singly and in combination: (a) overall stability of a foundation and of any adjacent slope; (b) bearing resistance; (c) pullout or uplift resistance; and (d) sliding, horizontal shear resistance, and passive resistance.

6.4.1.3 Serviceability limit state The SLS conditions to be considered shall be those causing the structure to become unserviceable and shall include the following: (a) foundation deformations that cause SLS limitations for the structure to be exceeded; (b) deformations that cause the riding surface or transitions between the approaches and the bridge superstructure to become unacceptable; and (c) deformations that cause unacceptable structure misalignment, distortion, or tilting.

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6.4.2 Effects on surroundings Changes that could occur at or near the site during and after construction shall be investigated during design. Effects on existing structures and on the adjacent ground to be considered shall include (a) changes in bearing and sliding resistance due to excavation or ground disturbance; (b) changes in groundwater level; (c) effects of blasting and pile driving; (d) effects of soil compaction; (e) effects of load changes on pressures within subsurface layers; and (f) effects of temperature changes, e.g., by heating or freezing.

6.4.3 Effects on structure For the appropriate limit state, consideration shall be given to all loads, imposed deformations, and foundation and component deformations. The variability and interdependence of these at various times during the design life of the structure shall be taken into account. The effects to be considered shall include (a) groundwater effects, including seepage, piping, and subsurface erosion; (b) forces due to lateral and vertical soil movements; (c) dynamic effects, including earthquakes and blasting; (d) frost penetration; (e) the variability of soil and rock strata; (f) scour and excavation; and (g) backfill compaction.

6.4.4 Components All footings, foundation components, and retaining structure components, including deep foundation units, ground anchors and ties, pole footings, and all components of crib and bin walls and MSE systems, shall be considered structural components and shall comply with the applicable requirements of this Code for the material in question.

6.4.5 Consultation Consultation between the structural Engineer and the geotechnical Engineer shall take place during planning, design, and construction. The geotechnical Engineer shall review the geotechnical aspects of the Plans before construction.

6.4.6 Inspection and quality control During construction, deep and shallow foundations, MSE, and ground anchors shall be inspected by the geotechnical Engineer to confirm that the site conditions are consistent with the design assumptions and to ensure that the geotechnical aspects of the work are carried out as intended. The results of the inspection and of observations at the site shall be documented.

6.5 Geotechnical investigation 6.5.1 General A geotechnical investigation shall be conducted to assess the suitability of the site for the proposed structure. Preliminary design information shall be established before and during the geotechnical investigation. To the extent practicable, this information shall include the following: (a) the type of structure; (b) the probable substructure locations; (c) the minimum footing depths; (d) the approximate magnitude and direction of foundation loads; (e) the approximate acceptable short-term and long-term foundation deformations; and November 2006

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(f)

the changes to the site and the surrounding area that could be caused by the structure during and after construction. The investigation shall be of sufficient scope to provide information on the subsurface conditions and to verify the assumptions made for the design and construction of the structure and associated approaches. The investigation shall include a subsurface exploration of sufficient depth to identify any stratum that could affect the performance of the proposed structure and approaches, and shall provide necessary information for design and construction, including appropriate geotechnical parameters to be used in design. The site investigation shall establish the geology, geomorphology, and hydrogeology of the site, determine whether the chemical nature of the soil, bedrock, and groundwater could affect the durability of the structure or its foundation units, provide details of matters requiring inspection during construction, and, where appropriate, provide requirements for post-construction observations.

6.5.2 Investigation procedures Site investigations, field tests, and laboratory testing shall be carried out in accordance with recognized or standardized procedures. The procedures used shall be documented.

6.5.3 Geotechnical parameters Geotechnical parameters shall be appropriate to the nature of the soil, rock, or anticipated backfill, the mode of failure or deformation being considered, and the variability of the soils and rock occurring at the site. Test procedures that will ensure appropriate accuracy shall be used.

6.5.4 Shallow foundations For shallow foundations, values of the factored geotechnical resistance at the ULS for the probable depths of embedment and footing sizes shall be determined. Geotechnical reactions at the SLS for associated deformation values shall be estimated in accordance with Clause 6.6.3.

6.5.5 Deep foundations For deep foundations, values of the factored geotechnical resistance at the ULS for the appropriate types and lengths of deep foundation units shall be determined. Installation procedures and group effects shall also be investigated. Foundation loads at SLS for associated deformation values shall be estimated in accordance with Clause 6.6.3.

6.5.6 Report The geotechnical report shall discuss and provide recommendations related to the following, as applicable: (a) the procedures used in the investigation; (b) the geology, geomorphology, and hydrogeology of the site; (c) the surface and subsurface conditions at the site (to be described in detail); (d) the groundwater elevations, including anticipated fluctuations; (e) representative values of the geotechnical parameters; (f) the types, depths, and widths of foundations; (g) the factored geotechnical resistance at the ULS for shallow foundations or deep foundation units or groups; (h) the deformations for anticipated SLS loads and the relevant range of footing sizes and typical pile configurations. When estimates of SLS loads are not available, SLS reactions for a range of corresponding estimated deformations shall be provided. This range shall include foundation settlements of 25 and 50 mm; (i) the effect on the geotechnical design of the construction of any associated works; (j) the values of earth pressures and corresponding values of soil or rock parameters for the design of retaining structures; (k) the construction and inspection measures required during construction and any special monitoring requirements related to the performance of the structure;

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(l) the geotechnical implications for adjacent property of the proposed structure and its construction; (m) the impact of events such as landslides and earthquakes on the structure; (n) the stability and settlement of approaches to the structure; and (o) erosion and frost protection requirements. Unless otherwise Approved, the report shall be signed and sealed by two Engineers, one of whom shall be a principal Engineer.

6.6 Resistance and deformation 6.6.1 General Geotechnical resistances or reactions used in the design shall ensure acceptable performance of the structure at both the ULS and the SLS. The methods of analysis shall include consideration of the duration of the loading and construction sequence. When site-specific geotechnical parameters are chosen for calculation of geotechnical resistance at the ULS and geotechnical reactions at the SLS, the variability of the conditions at the site, and the type of foundation and construction sequence, shall be considered.

6.6.2 Ultimate limit state 6.6.2.1 Procedures The geotechnical resistance at the ULS of shallow or deep foundations and anchors shall be determined from calculations, field tests, or assessments for a given soil or rock at a specific site. Unfactored geotechnical parameters shall be used to determine the geotechnical resistance at the ULS. The factored geotechnical resistance at the ULS of a deep or shallow foundation shall be the ultimate geotechnical resistance multiplied by the relevant resistance factor specified in Table 6.1, unless a higher value is Approved.

6.6.2.2 Geotechnical formulas The geotechnical formulas used for calculating ultimate resistance shall be appropriate to the soil and rock conditions at the site.

6.6.2.3 In-situ tests The parameters for calculation of geotechnical resistance at the ULS of a shallow foundation, anchor, pile, or group of piles may be determined from in-situ tests at the site. The factored resistance at the ULS shall be the ultimate geotechnical resistance obtained from the in-situ tests using an Approved method of interpretation and multiplied by the resistance factor specified in Table 6.1.

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Table 6.1 Geotechnical resistance factors (See Clauses 6.6.2.1, 6.6.2.3, 6.10.2.2, and 6.13.2.3.)

Application

Resistance factor

Shallow foundations Bearing resistance Passive resistance Horizontal resistance (sliding)

0.5 0.5 0.8

Ground anchors (soil or rock) Static analysis — Tension Static test — Tension

0.4 0.6

Deep foundations — Piles Static analysis Compression Tension Static test Compression Tension Dynamic analysis — Compression Dynamic test — Compression (field measurement and analysis) Horizontal passive resistance

0.4 0.3 0.6 0.4 0.4 0.5 0.5

6.6.2.4 Assessed value Provided that suitable geotechnical data, including the detailed stratigraphy, have been obtained from the site, ultimate geotechnical resistance may be estimated based on extrapolation of foundation performance under similar site conditions.

6.6.3 Serviceability limit state 6.6.3.1 General The SLS to be considered shall be those of the short-term and long-term total and differential deformations. The simultaneous occurrence of several types of deformation shall be considered.

6.6.3.2 Calculations The methods used for calculating SLS deformations and reactions shall employ unfactored geotechnical parameters appropriate to the site conditions.

6.6.3.3 Tests The time dependency of deformations shall be considered in planning the in-situ tests and interpreting test results to determine geotechnical reaction at the SLS.

6.6.3.4 Assessed values When applicable geotechnical data, including the detailed stratigraphy at the site, are available, measurements of actual deformation at sites with similar stratigraphy may be used to determine the geotechnical reactions and deformations at the SLS.

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6.6.3.5 Loads for SLS analysis Unfactored permanent and transitory loads shall be used for calculating total deformation in non-cohesive soils. Permanent loads and appropriate proportions of transitory loads shall be considered for the initial and time-dependent final deformations of cohesive soils.

6.6.3.6 Calculation considerations In calculating or predicting short-term and long-term deformations for the geotechnical reaction at the SLS, the following shall be taken into account: (a) the sequence of construction and changes in soil parameters as a consequence of construction; (b) observations of deformation of substructures in similar subsurface conditions; (c) the influence of soil variability, including layering; (d) induced stress and strain levels in relation to the geotechnical resistance at the ULS and preconsolidation pressure; (e) permeability, drainage, water content, and pore pressure; (f) the magnitude of the strains in the soils associated with the deformations; and (g) consolidation, creep, swelling, or collapse characteristics. A range of possible values shall be considered when values of deformation are to be used in structural analysis.

6.7 Shallow foundations 6.7.1 General The requirements of Clauses 6.7.2 to 6.7.5 shall apply to shallow foundations, including combined footings and mats, isolated footings, and wall footings.

6.7.2 Calculated geotechnical resistance at ULS The geotechnical resistance at ULS for a concentrically loaded footing founded in a uniform soil stratum, as shown in Figure 6.1, shall be calculated from the following or an alternative Approved method: qu = cNc sc ic + q‘Nq sq iq + 0.5γ ‘BNγ sγ iγ The parameters used for analysis shall be stated. When the load is eccentric, the footing shall be considered to have an effective concentrically loaded area of width B ‘ and length L‘ in accordance with Figure 6.2, where for a load, Q, the stress, q, is given by q = Q/B‘L‘ where B‘

= B – 2eB , but is less than L‘

L‘

= L – 2eL

The dimensionless bearing coefficients, Nc , Nq , and Nγ , depend only on the value of the effective internal friction angle, φ ‘, and are as shown in Figure 6.3. In the bearing resistance equation, shape factors that account for the width-to-length ratio of footings shall be calculated from sc

= 1 + (B ‘/L‘) (Nq /Nc )

sq

= 1 + (B ‘/L‘) (Nq /Nc )

sγ

= 1 – 0.4(B‘/L‘) The effects of a load inclination shall be accounted for by applying inclination factors as follows:

ic

= (1 – δi /90°)2

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iq

= (1 – δi /90°)2

iγ

= (1 – δi / φ ‘) 2

where

δi = angle of the resultant force with respect to the vertical CL

Slip line field associated with failure mechanism

Displacement field associated with failure mechanism Vertical settlement associated with punching

φ 45˚+ 2

B

Surcharge b a

III

f

e

III

I II

II

e1

d

f1 Weightless (g = 0) possesses c′,f′

Figure 6.1 Failure mechanism for footing (See Clause 6.7.2.) Centroid of effective area

Total load = Q Effective area, A′ = B′ x L′ Equivalent stress, q = Q/A′ L

V

L′ H

V

H

B′ B′/2

B

Plan of footing

B′/2

Section of footing with the effective area

Note: Values are factored and apply to the ULS.

Figure 6.2 Footing under eccentric load (See Clause 6.7.2.)

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Bearing coefficients Nc , Nq , and Ng

100

When f ′ = 0, Nc = 5.14 Nq = 1.00 Ng = 0.00

80

60

40

Nc Nq

20

Ng

0 0

10

20

30

40

Angle of internal friction, f ′ , degrees

Figure 6.3 Bearing coefficients (See Clause 6.7.2.)

6.7.3 Pressure distribution 6.7.3.1 Effective area For proportioning of concentrically loaded footings, a contact pressure of uniform intensity at the ULS shall be assumed. For eccentrically loaded footings, an equivalent effective area with a contact pressure of uniform intensity shall be assumed such that the centroid of the area coincides with the vertical component of the factored load.

6.7.3.2 Pressure distribution at the ULS for structural design For the structural design of footings, the more critical of the following shall be considered: (a) a uniform pressure distribution whose magnitude shall not be more than the factored geotechnical resistance; or (b) a linear pressure distribution where the maximum bearing pressure could be greater than the factored geotechnical resistance.

6.7.3.3 Pressure distribution at the SLS A linear distribution of contact pressure at the SLS shall be assumed. Tension at the interface between the footing and the soil or rock shall not be assumed.

6.7.3.4 Eccentricity limit In the absence of detailed analysis at the ULS for soil or rock, the eccentricity of the resultant of the factored loads at the ULS acting on a foundation, as shown in Figure 6.4, shall not exceed 0.30 times the dimension of the footing in the direction of the eccentricity being considered.

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Resultant force

CL of footing 0.3B

0.3B

Limits of eccentricity B

Figure 6.4 Eccentricity limit (See Clause 6.7.3.4.)

6.7.4 Effect of load inclination The inclination of the factored load shall be considered when the bearing resistance of shallow foundations is being determined. When the geotechnical resistance values are given for vertical forces, either the inclination reduction factors specified in Clause 6.7.2 or the reduction factors specified in Figure 6.5 shall apply in calculating the effect of load inclination. The factors specified in Figure 6.5 shall apply to the vertical factored geotechnical resistance only for embedment-to-width ratios (D/B‘) greater than 0.125 and for ratios of horizontal force to vertical force less than 0.55. The effects of load inclination for shallow foundations on rock shall be analyzed, taking into account any weaknesses in the rock.

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1.0

Reduction factor

0.8 Cohesive soil

D

Non-cohesive soil

0.6

B′

D/B′ = 0.125

0.4

B

D/B′ = 0.25 D/B′ = 0.5 D/B′ = 1.0

0.2

D/B′ = 2.0

0.0 0.0

0.1

0.2

0.3

0.4

0.5

0.6

Ratio of horizontal to vertical load

Figure 6.5 Load inclination reduction factors for bearing resistance,  ‘ = 30° (See Clause 6.7.4.)

6.7.5 Factored geotechnical horizontal resistance The factored geotechnical horizontal resistance shall not be less than the horizontal component of the factored load. The factored geotechnical horizontal resistance shall be taken as the lesser of the factored horizontal shear resistance of the soil or rock below the footing and the factored horizontal shear resistance of the interface between the footing and the soil or rock. Where appropriate, the factored horizontal passive resistance of the soil or rock shall be included. In the absence of a detailed analysis, the following shall be used to calculate the factored geotechnical horizontal resistance within the soil close to the soil-structure interface: Hrs = 0.8A‘c‘ + 0.8V tan ‘ > Hf In the absence of a detailed analysis, the following shall be used to calculate the factored geotechnical horizontal shear resistance at the interface between the footing and the soil or rock: 

Hri = 0.8A‘c‘ + 0.8V tan  > Hf The effective cohesion, c‘, shall be zero in the absence of detailed test data. The effective contact area, A‘, shall be the smallest area required to carry the minimum vertical loads. When the subgrade soil is clay, the short-term case shall also be checked using tan  ‘ = 0 and c ‘ equal to either the undrained shear strength or adhesion at the interface. When the passive pressure resistance of the soil or rock in front of the wall or some portion thereof is considered as contributing to resistance, the soil or rock properties and the acceptability of the movement required to develop the passive condition shall be considered. The presence of planes of weaknesses and discontinuities in the soil or rock beneath a foundation and the effects of buoyancy and seepage shall be considered in determining horizontal resistance. Sliding resistance for footings placed on smooth or inclined bedrock surfaces shall be supplemented by keys, dowels, or sockets unless horizontal resistance and stability can be ensured by other means.

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6.8 Deep foundations 6.8.1 General The requirements of this Clause apply to vertical and inclined piles acting as single units or in a group.

6.8.2 Selection of deep foundation units For deep foundations the following shall be considered: (a) the suitability of the type of pile; (b) the reliability of the soil or rock in providing the required resistance; (c) the durability of the pile material; (d) the movement of the soil surrounding the piles; (e) scour, future dredging, or excavation; (f) the effect of groundwater on the installation of piles; (g) the existence of sloping bedrock, boulders, or construction debris; (h) the ductility of the pile in seismic areas; and (i) the effects of frost.

6.8.3 Vertical load transfer All loads on a deep foundation shall be assumed to be transferred to the underlying strata by the deep foundation units and any contribution arising from direct bearing of the footing on the soil shall be neglected.

6.8.4 Downdrag Downdrag on piles caused by settlement of the surrounding soil shall be considered a load and shall be specified by the geotechnical Engineer. For the purposes of calculation, downdrag effects on piles shall be considered to be those of settlement and structural resistance. Downdrag loads shall be evaluated by the geotechnical Engineer by taking into account the specific site conditions. If neutral plane concepts are used, the location of the plane of zero relative movement between the soil and the pile for a pile or group of piles shall be determined by using unfactored loads and unfactored geotechnical parameters. The downdrag load, along with other loads, shall be applied to the pile or pile group using load factors specified in Section 3.

6.8.5 Factored geotechnical axial resistance 6.8.5.1 General The methods used to establish and verify the geotechnical axial resistance shall be appropriate to the site, to the soil or rock conditions, to the type of deep foundation unit, and to the proposed method of installation. At least one of the following methods shall be used: (a) static analysis; (b) static pile load test; (c) dynamic analysis (for compression only); (d) dynamic pile test (for compression only); and (e) assessed value. For driven piles, an assessment shall be made to determine that the piles can be installed to design depth and provide the design resistance without inducing damaging stresses. The factored geotechnical axial resistance shall not exceed the factored structural resistance of the pile.

6.8.5.2 Static analysis The geotechnical resistance at ULS of piles shall be calculated as follows: Ru = total shaft resistance + toe resistance =  As‘ rs + At‘ rt

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where As‘ rs

= ultimate shaft resistance, kN

At‘rt

= ultimate pile toe resistance, kN

∑ As‘rs indicates the summation over the length of the pile in those strata considered as contributing to the shaft resistance. For re-entrant surfaces of a pile shaft, e.g., H-piles, the shaft resistance shall be taken as the lesser of the soil-pile interface resistance and the shear resistance on a plane through the soil joining the re-entrant corners.

6.8.5.3 Static pile load tests Static test loads applied to a pile shall normally be measured to an accuracy of ± 2% and vertical displacement to a precision of ± 0.025 mm.

6.8.5.4 Dynamic analysis and tests The dynamic analysis and tests shall consider the hammer-pile-soil systems proposed for or used at the site.

6.8.5.5 Limitation for tension piles In determining the geotechnical axial resistance at the ULS of a pile in tension, only the shaft resistance and the weight of the pile shall be considered. For tapered piles, tensile resistance shall not be considered unless demonstrated by testing at the site.

6.8.5.6 Relaxation of driven piles For stratigraphies where relaxation of the resistance of the driven pile can occur, the design shall take into consideration a possible loss of resistance with time.

6.8.6 Group effects — Vertical loads 6.8.6.1 Load distribution At the SLS, piles and pile footings shall be assumed to respond linearly to applied loads. Either linear or non-linear responses to applied loads shall be assumed in determining the loads acting on individual piles within a pile group at the ULS. For other structural components, a linear response to applied loads shall be assumed when the forces at the ULS are calculated. For this case, the forces acting on the piles shall not be limited by the factored geotechnical resistance of the piles.

6.8.6.2 Group resistance The factored vertical resistance of a pile group shall be determined as follows: (a) the factored geotechnical resistance of a group of piles bearing on rock, dense sand, or gravel with no weak strata beneath the bearing layer shall be taken as the sum of the factored axial geotechnical resistances of the individual piles in the group; or (b) the factored geotechnical resistance of a group of piles that derive their resistance primarily from shaft friction shall be taken as the lesser of the following: (i) the sum of the factored geotechnical resistances of the individual piles in the group; or (ii) the factored geotechnical resistance of an equivalent block enclosing the pile group.

6.8.7 Factored geotechnical lateral resistance 6.8.7.1 General The factored geotechnical lateral resistance of a pile shall be determined from at least one of the following: (a) static analysis; (b) static tests; and (c) assessment. November 2006

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6.8.7.2 Static analysis The factored geotechnical horizontal resistance of a pile shall be taken as the sum of the horizontal component of the factored passive resistance of the soil against the pile and the horizontal component of the factored axial load present in an inclined pile. The factored horizontal resistance of a group of piles shall take group effects into consideration.

6.8.7.3 Lateral deflection The resistance provided by the soil to a pile as the pile deflects laterally shall be considered using unfactored geotechnical parameters. The pile shall be modelled as a beam-column supported by springs equivalent to the passive reaction distributed along the shaft. A linear or non-linear resistance-displacement relationship may be assumed. The relationship shall reflect the type of pile and the resistance and deformation characteristics of the soil. Both short-term static and cyclic responses shall be considered. Soil properties at various elevations shall be based on test data appropriate to similar soil types.

6.8.8 Structural resistance 6.8.8.1 Supported length That portion of a deep foundation unit that is permanently in contact with soil shall be considered a laterally supported compression member.

6.8.8.2 Unsupported length The length of pile between points of contraflexure in contact with air or water, including any buried length that could become exposed, shall be considered laterally unsupported. Engineering judgment shall be used to determine whether a soft soil provides adequate lateral support for a pile.

6.8.8.3 Structural instability For piles not permanently in contact with soil, the possibility of structural instability of individual piles and of a pile group shall be considered.

6.8.8.4 Transporting, handling, and driving Prefabricated deep foundation units shall be of sufficient strength to withstand force effects resulting from transporting, handling, and driving.

6.8.8.5 Factored structural resistance The factored structural resistance of piles at the ULS shall be determined in accordance with the applicable Sections of this Code. In the case of embedded laterally supported piles, a reduction factor of 0.75 shall be applied. The reduction factor may be modified to increase the resistance if warranted by an assessment of the design and construction conditions for the site.

6.8.9 Embedment and spacing 6.8.9.1 Embedment in footing Where the heads of piles are encased in a concrete footing or pile cap, the heads shall project at least 300 mm into the footing after all material that has been damaged by driving has been removed. For concrete and concrete-filled steel pipe piles connected to pile caps using reinforcing steel, the minimum embedment may be reduced to 100 mm. The reinforcement shall be developed by embedment length, end anchorage, or both in accordance with Section 8.

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6.8.9.2 Pile spacing Where the centre-to-centre spacing of piles at the underside of the footing is less than 2.5b or less than 750 mm, the effects of interaction between piles shall be considered.

6.8.10 Pile shoes and splices 6.8.10.1 Pile shoes or points Where soil or rock conditions warrant, pile shoes or points shall be used to ensure the integrity of piles during driving or to ensure effective contact with an end-bearing stratum. Where shaft friction is required to contribute significantly to pile resistance, the pile shoes shall be shaped to avoid reducing shaft friction or pile shoes shall not be used.

6.8.10.2 Splices The structural resistance of a pile splice shall be at least equal to that of the pile. Where shaft friction is required to contribute significantly to pile resistance, the pile splices shall be shaped to avoid reducing shaft friction. Splicing of wood piles shall require Approval.

6.9 Lateral and vertical pressures 6.9.1 General In calculating the magnitude and direction of the lateral pressures due to backfill, the following shall be considered: (a) the nature and density of the backfill; (b) the mobilized parameters of the backfill; (c) the movement of the structure relative to the backfill; (d) wall friction; (e) the slope of the surface of the backfill; (f) force effects due to compaction of the backfill; (g) surcharge and superimposed loads; (h) groundwater and seepage; (i) the temperature regime; (j) dynamic effects, including earthquakes; (k) the adequacy of surface and subsurface drainage; and (l) protection against pressures due to freezing of free water within the backfill.

6.9.2 Lateral pressures 6.9.2.1 General Lateral pressures for use in the design of a structure shall include the effects of any superimposed dead and live load and the following shall apply: (a) For an unrestrained structure, an active pressure due to backfill shall be considered in proportioning the width of the footing and the arrangement of piles. Lateral pressure due to compaction shall not be considered. (b) For an unrestrained structure, an active pressure due to backfill and pressure due to compaction shall be considered in the proportioning of the structural sections. (c) For a restrained structure, an at-rest pressure and pressure due to compaction shall be considered in the proportioning of the width of the footing, the arrangements of piles, and the structural sections. (d) For structures where the interaction between structure and soil is considered to be neither restrained nor unrestrained, the earth pressure shall be determined by recognized methods of analysis from consideration of the movement of the structure relative to the retained soil and of the limit state condition in the supporting foundation. November 2006

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Where it is possible for the base of a soil-retaining structure to move laterally at the ULS and thereby to mobilize passive pressure in foundation soils, the passive pressure shall be considered a resistance.

6.9.2.2 Calculated pressures Pressures shall be calculated using representative unfactored soil parameters and recognized methods of analysis. The compaction pressures specified in Clause 6.9.3 shall be used as minimum values. Where the sloping surcharge exceeds 5°, an evaluation by a geotechnical Engineer shall be performed.

6.9.2.3 Equivalent fluid pressures Equivalent fluid pressures shall be considered acceptable for calculating active and at-rest earth pressures for retaining structures with a stem height not exceeding 6.0 m, provided that well-drained granular material fills the space between the back face of the wall and a limiting line drawn at 45° to the horizontal from where the back face of the footing meets the bottom of the footing. In the absence of calculated values developed from established soil properties for retaining walls having a stem height not exceeding 6.0 m, the equivalent fluid pressures, not including compaction pressures, shall be in accordance with Table 6.2. The effect of shear resistance or wall friction between the back face of the wall and the soil may be neglected. The equivalent fluid pressure values specified in Table 6.2 shall not apply in the following circumstances: (a) if the soil beyond the granular material limiting line specified in this Clause consists of soft cohesive soil or organic soils; (b) if the ground surface within the granular material limiting line slopes upward from the wall at more than 5° to the horizontal; or (c) if the groundwater table is above the base of the footing.

Table 6.2 Equivalent fluid pressure per metre width, kPa/m (See Clause 6.9.2.3.) Angle of internal friction

Pressure

Active condition

30–35° Greater than 35°

7z 6z

At-rest condition

30–35° Greater than 35°

11z 10z

6.9.3 Compaction surcharge For retained backfill that is placed and compacted in layers, the lateral force caused by compaction shall be considered. For the calculated pressures required by Clause 6.9.2.2 and the granular backfill required by Clause 6.9.2.3, a lateral pressure varying linearly from 12 kPa at the fill surface to 0 kPa at a depth of 1.7 m below the surface for angles of internal friction from 30 to 35°, or 2.0 m below the surface for angles of internal friction greater than 35°, shall be added to the lateral earth pressure, as shown in Figure 6.6, in lieu of calculation by recognized methods of analysis. In the absence of detailed analysis, the additional lateral pressure due to the effects of compaction for restrained structures shall be taken as the at-rest pressure intensity at a given elevation multiplied by 0.15. The total lateral pressure for restrained structures shall be added to the lateral pressure corresponding to light compaction, as shown in Figure 6.6.

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Minimum of 12 kPa (a)

(b)

(a) Lateral pressure corresponding to light compaction

(b) Lateral pressure corresponding to active condition for unrestrained structures and at-rest condition, plus an allowance for compaction for restrained structures

Figure 6.6 Compaction effects (See Clause 6.9.3.)

6.9.4 Effects of loads The effects of loads of various inclinations shall be considered in the assessment of the ultimate resistance of foundations supporting earth-retaining structures. Where a mass of soil is retained behind a wall, combinations of load factor for both horizontal and vertical load shall be considered. For earth pressures acting on a buried structure such as a culvert or partial frame, where different soil masses are possible on either side of the structure, the maximum or minimum load factors specified in Section 3 shall apply.

6.9.5 Surcharge The horizontal and vertical force effects due to footings and other loads placed in or on the backfill shall be taken into account. A live load surcharge shall apply where the backfill supports highway live loads within a distance from the back face of the wall equal to the effective height. Where an approach slab extends over this distance and is supported by or at the wall, the surcharge shall not apply. The live load surcharge shall be equal to an equivalent additional fill height of 0.80 m. The surcharge shall be assumed to act above the finished grade and over the length of the retaining structure.

6.9.6 Wheel load distribution through fill When the depth of fill over a structure is 0.60 m or more, wheel loads shall be uniformly distributed at the surface of the structure over a rectangle, the sides of which are equal to the footprint of the wheel of the CL-W Truck as specified in Clause 3.8.3.1 plus 1.75 times the depth of fill. When distributed wheel loads from two or more wheels overlap, the total load of those wheels shall be uniformly distributed over the smallest rectangle that includes their individual areas, but the total width of distribution shall not exceed the total width of the structure supporting the fill. When the depth of fill over a structure is less than 0.60 m, no distribution beyond the footprints of the wheels shall be considered.

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6.10 Ground anchors 6.10.1 Application Clause 6.10 applies to the design, installation, stressing, inspection, and testing of temporary and permanent ground anchor systems. It applies to soil and rock anchors, but not to soil nailing and MSE systems. Sections 8, 9, and 10 shall apply to ground anchors used with concrete structures, wood structures, and steel structures, respectively.

6.10.2 Design 6.10.2.1 General The designer shall assess the performance requirements for the ground anchor system and the available site information. The pullout performance shall be sufficient for the service life of the installation. The following shall be considered: (a) the site conditions; (b) the soil and rock properties; (c) ground discontinuities; (d) ground creep susceptibility; (e) the grout-ground interface; (f) the diameter of the hole; (g) the construction methods and equipment; (h) the grouting procedure; (i) the strength of the grout; (j) the tendon-grout bond; (k) the structural components; (l) the aggressiveness of the environment; and (m) corrosion protection. The durability of the anchorage system shall be designed for the service life of the installation. Installations with a design life exceeding two years shall be considered permanent.

6.10.2.2 Factored geotechnical resistance at the ULS and geotechnical reaction at the SLS Potential failure mechanisms at ultimate limit states shall be identified and evaluated. The factored geotechnical resistance at the ULS shall be determined using the resistance factors specified in Table 6.1. The geotechnical resistance at the ULS and the geotechnical reaction at the SLS shall be determined by one or more of the following: (a) a static analysis based on geotechnical information obtained at the site; (b) pullout tests; or (c) an assessment by extrapolation of anchor behaviour under similar site conditions.

6.10.2.3 Spacing, bond length, and free-stressing length The spacing, bond length, and free-stressing length shall be sufficient to ensure performance of the ground anchor. The centre-to-centre spacing between bond lengths shall not be less than four times the diameter of the bored hole. The bond length shall be sufficient to develop the required pullout resistance and shall not be less than 3 m. The length of the free-stressing zone shall locate the bond length outside the failure wedge.

6.10.3 Materials and installation 6.10.3.1 Prestressing steel and attachments The prestressing steel shall comply with CSA G279.

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Tendons shall be designed so that (a) the factored resistance at the ULS does not exceed 60% of the specified tensile strength of the prestressing steel; (b) the transfer or lockoff load does not exceed 70% of the specified strength of the prestressing steel; (c) the maximum test load does not exceed 80% of the specified strength of the prestressing steel; and (d) the anchorage components and couplers for tendons develop at least 100% of the specified strength of the tendon.

6.10.3.2 Grout or concrete for bond length The strength of grout or concrete for the bond length shall be adequate for the anchor performance specified in Clause 6.10.3.1. The use of post-grouting techniques shall be considered as a means of enhancing anchor resistance. Post-grout pressures shall be controlled so that the overlying soil is not disturbed.

6.10.3.3 Backfill for free-stressing length The backfill for the free-stressing length shall completely fill the annular space between the ground anchor tendon and the borehole wall and shall prevent any transfer of the anchor load to the free-stressing length.

6.10.3.4 Corrosion protection For temporary anchors, the prestressing steel shall retain adequate structural strength during the required service life of the anchor and the provisions for corrosion protection shall be adequate for this purpose. For permanent anchors, double corrosion protection, providing two separate corrosion barriers to the prestressing steel, shall be incorporated.

6.10.4 Anchor testing 6.10.4.1 General Anchor testing shall comply with accepted and Approved standards and with the following requirements: (a) A sufficient number of pre-production tests shall be carried out where in-situ tests are required as a basis for grout-to-ground bond design. (b) A sufficient number of performance tests shall be carried out to determine whether the anchor design has sufficient load-carrying capacity and creep performance. (c) Proof tests shall be carried out on all production anchors to confirm that anchor pullout performance is sufficient and that the free-length requirements have been satisfied. (d) Liftoff tests shall be carried out on selected production anchors to confirm creep performance.

6.10.4.2 Acceptance criteria The acceptance criteria for anchor performance shall be sufficient for meeting Approved standards and project-specific requirements.

6.11 Sheet pile structures 6.11.1 Application Clauses 6.11.2 to 6.11.4 apply to retaining structures that consist of driven sheet piles with or without ties.

6.11.2 Design In the design of all components and the determination of deformations, the method of analysis used shall assume a linear or non-linear resistance-displacement relationship in accordance with the resistance and deformation characteristics of the soil and of the sheet piles. Long-term and short-term static and cyclic responses shall be considered. November 2006

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The determination of soil properties at various elevations shall be based on field tests or assessed values.

6.11.3 Ties and anchors 6.11.3.1 Deadman anchors In determining the required length of tie rods connected to deadman anchors, the possible reduction in anchor resistance caused by interference between the active failure wedge behind the sheeting and the passive failure wedge in front of the anchor shall be considered.

6.11.3.2 Pile anchors Tie rod anchorages consisting of vertical or inclined piles shall be designed in accordance with Clause 6.8.

6.11.3.3 Tie load The factored load to be resisted by anchorage ties shall not exceed 80% of the calculated factored tensile resistance at the ULS calculated in accordance with Section 10.

6.11.3.4 Sagging of tie rods When tie rods are underlain by compressible soils that can undergo significant vertical deformation under surcharge loading, the possibility of additional tensile stresses being induced in the tie rods because of sagging shall be considered.

6.11.4 Cellular sheet pile structures In the proportioning of cellular sheet pile structures, the following shall be considered: (a) the type of pile; (b) ease of installation; (c) the type of backfill and its geotechnical properties; (d) the groundwater and free water levels; (e) acceptable deformations; (f) durability; (g) future dredging or excavation; and (h) scour.

6.12 MSE structures 6.12.1 Application Clause 6.12 applies to the design of reinforced-soil-type retaining wall systems consisting of prefabricated facing elements, reinforced soil mass, and soil-reinforcing elements, normally comprising metal strips, geogrids, or metal mesh. Components made of materials that are not covered by this Code shall be used only when short- and long-term testing have established their suitability for the intended purpose. The testing shall establish all relevant properties, including those pertaining to durability, dimensional stability, and creep. The design of MSE structures shall take into consideration both overall stability and internal stability.

6.12.2 Design 6.12.2.1 General The design shall be based on accepted methods of analysis and shall take into consideration the magnitude of strains expected in the soil-reinforcing elements and the soil; internal stability within the zone of the soil-reinforcing elements; and the site-specific external stability of the MSE geometry.

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6.12.2.2 Calibration When established empirical methods of analyzing the internal resistance of reinforced-soil-type structures are available and are based on working stress design methods, such methods shall be used to check the results of the analytical limit states design method.

6.12.2.3 Factors for consideration In determining proportions, including those of the founding level and the overall width of MSE structures, the following shall be considered: (a) the type and spacing of soil-reinforcing elements; (b) the backfill type and compaction; (c) the durability of components; (d) scour, future dredging, or excavation; and (e) groundwater and seepage.

6.12.3 Backfill Backfill within and behind the reinforced soil mass shall consist of Approved earth material compacted using methods and equipment appropriate to the type of structure.

6.13 Pole foundations 6.13.1 Application Clause 6.13 applies to the design of pole foundations, including foundations for high-mast lighting poles, in which a vertical cylindrical footing is formed by augering or excavating into the ground, securing a reinforcement cage and pole base anchorage system in the hole, and casting the footing concrete around them against undisturbed soil.

6.13.2 Design 

6.13.2.1 General The embedded length and diameter of the foundation shaft that is considered to be effective in resisting horizontal pressure shall be determined by accepted analytical methods. The foundation shaft and any concrete extension thereof that is not considered part of the foundation shall comply with all reinforced concrete substructure requirements of this Code. Anchor rods and anchorages shall comply with the applicable requirements of Sections 8, 10, and 12.

6.13.2.2 Assumptions Transverse loads, including those caused by bending effects, shall be assumed to be resisted by the horizontal reaction of the ground surrounding the foundation shaft. In the determination of horizontal soil reactions, the foundation shaft shall be considered to be infinitely stiff. In both cohesive and non-cohesive soils, allowance shall be made at the ULS for the end effect on transverse distribution of pressures within the soil mass that resist the horizontal movement of the foundation shaft. When significant proportions of the horizontal soil/rock reactions are due to permanent loads, allowance shall be made for the effects of long-term loading on foundation deformations and resistance.

6.13.2.3 Ultimate limit state At the ULS, the full passive resistance of the soil shall be assumed to have developed. The passive resistance factor applied shall be as specified in Table 6.1.

6.13.2.4 Serviceability limit state The SLS consideration shall be rotation of the footing. Rotation shall not exceed the tilting limit for the serviceable function of the pole. The rotation shall be calculated using an Approved method of analysis. October 2011 (Replaces p. 249, November 2006)

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Section 7 — Buried structures 7.1 7.2 7.3 7.3.1 7.3.2 7.4 7.5 7.5.1 7.5.2 7.5.3 7.5.4 7.5.5 7.5.6 7.6 7.6.1 7.6.2 7.6.3 7.6.4 7.6.5 7.6.6 7.6.7 7.7 7.7.1 7.7.2 7.7.3 7.7.4 7.7.5 7.7.6 7.7.7 7.8 7.8.1 7.8.2 7.8.3 7.8.4 7.8.5 7.8.6 7.8.7 7.8.8 7.8.9 7.8.10 7.8.11 7.8.12 7.8.13 7.8.14 7.8.15

Scope 252 Definitions 252 Abbreviation and symbols 254 Abbreviation 254 Symbols 254 Hydraulic design 258 Structural design 259 Limit states 259 Load factors 260 Material resistance factors 260 Geotechnical considerations 261 Seismic requirements 262 Minimum clear spacing between conduits 262 Soil-metal structures 263 General 263 Structural materials 265 Design criteria 266 Additional design requirements 271 Construction 273 Special features 275 Site supervision and construction control 275 Metal box structures 276 General 276 Structural materials 276 Design criteria 277 Additional design considerations 278 Construction 278 Special features 279 Site supervision and construction control 279 Reinforced concrete buried structures 279 Standards for structural components 279 Standards for joint gaskets for precast concrete units 280 Installation criteria 280 Loads and load combinations 287 Earth pressure distribution from loads 288 Analysis 291 Ultimate limit state 291 Strength design 292 Serviceability limit state 295 Fatigue limit state 295 Minimum reinforcement 295 Distribution reinforcement 296 Details of the reinforcement 296 Joint shear for top slab of precast concrete box sections with depth of cover less than 0.6 m 297 Construction 297

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Section 7 Buried structures 7.1 Scope This Section specifies requirements for the analysis and design of buried structures of the following types: (a) soil-metal structures; (b) metal box structures; and (c) reinforced concrete structures. This Section also specifies construction procedures, properties and dimensions of engineered soil components, and requirements for construction supervision.

7.2 Definitions The following definitions apply in this Section: Arch — a soil-metal or reinforced concrete structure in which the conduit wall is not continuous around the perimeter of the bridged opening and the conduit wall is supported on footings. Arching — the transfer of pressure or load between the soil masses adjacent to and above a conduit that move relative to one another. Positive arching results in the transfer of loads away from the conduit; negative arching produces the opposite effect. Bedding — the prepared portion of engineered soil on which the base of a closed conduit wall is placed. Bevelled end — the termination of the wall of a conduit, cut at a plane inclined to the horizontal. Buried structure — a structure that has one or more conduits and is designed by taking account of the interaction between the conduit wall and engineered soil. Camber — an adjustment required in the longitudinal profile of bedding to compensate for post-construction settlement. Compaction — the process of soil densification, at a specified moisture content, by the application of pressure through rolling, kneading, tamping, rodding, or vibratory actions of mechanical or manual equipment. Conduit — the bridged opening of a buried structure. Conduit wall — the corrugated metal plate shell or reinforced concrete wall lining a conduit. Connection — an overlapped bolted joint between two structural metal plates or a joint between two reinforced concrete elements. Controlled low-strength material — a mixture of soil, a small amount of cement, and a large amount of water and other admixtures that flows easily in its initial stages and hardens to a 28-day compressive strength of 1 to 5 MPa. Crown — the highest point of the transverse section of a conduit wall. Deep corrugations — structural plate corrugations with a pitch between 380 and 400 mm and a rise between 140 and 150 mm.

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Depth of cover — the vertical distance between the roadway surface and the conduit wall, as shown in Figures 7.3, 7.8, and 7.11. Engineered soil — soil selected and placed to achieve desired geotechnical properties. Foundation — the soil or rock underlying a conduit and the engineered soil. Frost-susceptible soil — soil that tends to heave excessively under frost action, resulting in a severe degradation in strength and stiffness. Haunch — the following: (a) in a soil-metal structure or circular concrete structure, the portion of the conduit wall between the spring line and the top of the bedding or footing; (b) in a metal-box structure, the curved portion of the conduit wall between the sidewall and top, sometimes referred to as the shoulder; and (c) in a concrete box section, the stiffened corner portions. Horizontally elliptical pipe — an elliptical pipe whose the major diameter is horizontal and greater than 1.10 times the minor diameter. Invert — the lowest point of a conduit at a transverse section or the bottom segment of a conduit wall. Longitudinal direction — the direction of a conduit axis that is parallel to the locus of the crown. Longitudinal stiffeners — stiffeners that comprise continuous structural elements, are usually of reinforced concrete construction, and are attached along the length of the metallic shell at the junction of the top and side arcs. Metal box structure — a structure that is fabricated from corrugated metal plates, has the details shown in Figure 7.7, and in which the design of the conduit wall is mainly governed by flexure. Modified proctor density — the maximum dry density of a soil determined in accordance with ASTM D 1557. Modulus of soil stiffness — the ratio of the radial contact pressure to the radial strain in a soil. Obvert — the highest point of a conduit at a transverse section or the top segment of a metal conduit wall. Overfill — the soil placed above and beyond required structural backfill. Pipe-arch — a conduit that consists of arched upper and side portions and is structurally continuous with an invert whose radius of curvature is greater than that of the other portions. Re-entrant arch — an arch whose spring lines lie above the footings. Rise — the maximum vertical clearance inside a conduit at a transverse section, measured at the mid-depth of the corrugations of metal structures. Round pipe — a circular or elliptical pipe whose major diameter does not exceed 1.10 times the minor diameter. Shallow corrugations — structural plate corrugations with a pitch between 150 and 230 mm and a rise between 50 and 65 mm. Shoulder — the portion of a conduit wall between the crown and the spring line. Sidefill — the portion of structural backfill illustrated in Figures 7.8 and 7.9 for circular concrete pipes and in Figures 7.10 and 7.11 for concrete box sections.

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Sidewall — the vertical or nearly vertical portion of a conduit wall in a metal or concrete box structure. Soil-metal structure — a structure fabricated from corrugated metal sheets or plates. Soil modification — improvement of soil strength, compressibility, or permeability by geotechnical means, including the use of geosynthetics. Span — the maximum horizontal clearance inside a conduit at a transverse section, measured for soil-metal structures at the mid-depth of the corrugations. Spring line — the locus of the outermost points of the sides of a conduit. Standard installation — the installation of buried concrete structures as specified in Clauses 7.8.3.5 and 7.8.3.6. Standard Proctor density — the maximum dry density of a soil, determined in accordance with ASTM D 698. Stiffener — a structural member connected to a conduit wall to improve its strength and stiffness. Structural backfill — the engineered soil placed around a conduit in a controlled manner, as specified in Clauses 7.6.5.6.1, 7.7.5.1.1, and 7.8.15.5. Thrust — the circumferential compressive force in a conduit wall, per unit length of the wall. Transverse direction — the direction in the horizontal plane perpendicular to the longitudinal direction. Transverse section — a section in the vertical plane normal to the longitudinal direction. Vertically elliptical pipe — an elliptical pipe whose major diameter is vertical and greater than 1.10 times the minor diameter.

7.3 Abbreviation and symbols 7.3.1 Abbreviation The following abbreviation applies in this Section: CLSM — Controlled low-strength material

7.3.2 Symbols The following symbols apply in this Section: A

=

cross-sectional area of a corrugated metal conduit wall per unit length in the longitudinal direction, mm2/mm

AH

=

horizontal acceleration ratio due to earthquake loading (dimensionless), equal to the zonal acceleration ratio in Clause 4.4.3

AL

=

axle load, kN (see Clause 7.7.3.1.3)

AV

=

vertical acceleration ratio due to earthquake loading (dimensionless), equal to two-thirds of the horizontal acceleration ratio, AH

Ac

=

axle load during construction, kN

Af

=

factor used to calculate the thrust due to dead load in a conduit wall

As

=

area of tensile reinforcement per width b, mm2/mm

Asi

=

total area of the inner cage reinforcement area per width b, mm2/mm

Aso

=

total area of the outer cage reinforcement area per width b, mm2/mm

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Avs

=

area of stirrup reinforcement to resist shear and radial tension in each line of stirrups at circumferential spacing, sv , mm2 per width b

B1

=

crack-control coefficient for the effect of spacing and number of layers of reinforcement for all sizes of welded wire fabric and hot-rolled bars 10M or smaller with a longitudinal spacing of less than or equal to 100 mm

b

=

width of the concrete section that resists structural force effects, mm

Cs

=

axial stiffness parameter for soil-metal structures (see Clause 7.6.3.1.2)

C1

=

crack-control coefficient for the type of reinforcement; tandem axle coefficient for metal box structures (see Clause 7.7.3.1.3)

Dh , Dv =

dimensions relating to the conduit, m (see Figures 7.1 and 7.2)

Di

=

inside diameter of concrete pipe, mm

Do

=

outside diameter of concrete pipe, mm

DLA

=

dynamic load allowance expressed as a fraction of live load

d

=

depth of corrugation, mm; distance from compression face to centroid of tension reinforcement, mm

dc

=

corrugation depth, mm

E

=

modulus of elasticity, MPa

Em

=

modified modulus of soil stiffness, MPa

Es

=

secant modulus of soil stiffness, MPa

FN

=

coefficient for effect of thrust on shear strength

Fc

=

factor for effect of curvature on diagonal tension (shear) strength in curved components

Fcr

=

crack-width control factor for adjusting crack control

Fd

=

factor for crack-depth effect resulting in increase in diagonal tension (shear) strength with decreasing d

Fm

=

reduction factor for modifying buckling stress in multi-conduit structures

Frt

=

factor for pipe size effect on radial tension strength of pipe

Fy

=

cold-formed yield stress of a metal conduit wall, MPa

fb

=

factored failure stress in compression in a metal conduit wall, MPa

fc‘

=

design compressive strength of concrete, MPa

fs

=

maximum service load strength of reinforcing steel for crack control, MPa

fv

=

maximum developable strength of stirrup material, MPa

fy

=

design yield strength of reinforcement, MPa

H

=

depth of cover or height of overfill, m

H‘

=

half the vertical distance between crown and spring line, m

Hc

=

depth of cover at intermediate stages of construction, m

He

=

effective value of depth of cover above a conduit (used for calculating bending moment due to dead load in a complete soil-metal structure), m

Hmin

=

minimum allowable depth of cover above a conduit, m

h

=

overall thickness of member (wall thickness), mm

I

=

second moment of cross-sectional area, A, about the neutral axis of a corrugated section in the longitudinal direction of the conduit, mm4/mm

K

=

factor representing the relative stiffness of a conduit wall with respect to the adjacent soil; the effective length factor used in a P-Δ an alysis

kM1,

=

factors used in calculating moments in soil-metal structures (see Clauses 7.6.3.3.1 and

kM2, kM3

7.6.3.3.2)

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haunch moment reduction factor for metal box structures

k1 , k 2 , =

factors used in calculating dead load and live load moments in soil-metal and metal box

k3 , k 4

structures

LL

=

line load equivalent to the live load acting on a metal structure, kN/m

Lc

=

line load equivalent to the construction load acting on a metal structure, kN/m

Lhi

=

horizontal dimension of concrete box section to inside of walls, mm

Lho

=

horizontal dimension of concrete box section to outside of walls, mm

Lvi

=

vertical dimension of concrete box section to inside of top and bottom slabs, mm

Lvo

=

vertical dimension of concrete box section to outside of top and bottom slabs, mm

lt

=

length of dispersed live load at crown level measured transversely, m (see Clause 7.6.3.1.3)

lθ

=

total additional arc length beyond calculated arc lengths requiring stirrups, mm

M

=

unfactored moment in a soil-metal structure, kN•m/m

MB

=

additional moment in the wall of a soil-metal structure due to a height of fill, Hc , above the crown, kN•m/m

MC

=

additional moment in a soil-metal structure due to construction live loads, kN•m/m

MD

=

sum of the intensities of bending moments at the crown and haunch in a metal box structure due to dead load, kN•m/m; moment in the wall, kN•m/m

ME

=

additional moment in a metal box structure due to earthquake loading, kN•m/m

ML

=

sum of the crown and haunch bending moments in a metal box structure due to live load; moment in the wall, kN•m/m

MP

=

unfactored plastic moment capacity of a corrugated metal section, kN•m/m

MPf

=

factored plastic moment capacity of a corrugated metal section, kN•m/m

McD

=

crown bending moment in a metal box structure due to dead load, kN•m/m

McL Mcf MhD Mhf MhL Mnu

= = = = = =

Mu M1 mf NF Nu

= = = = =

n P

= =

crown bending moment in a metal box structure due to live load, kN•m/m total factored crown bending moment in a metal box structure, kN•m/m haunch bending moment in a metal box structure due to dead load, kN•m/m total factored haunch bending moment in a metal box structure, kN•m/m haunch bending moment in a metal box structure due to live load, kN•m/m factored moment in concrete structures, as modified for effects of compressive or tensile thrust, N•mm per width b factored moment acting on a cross-section of a concrete structure, N•mm per width b moment in a soil-metal structure resulting from fill to the crown level, kN•m/m modification factor for multi-lane loading flexibility number used in calculating moments in a soil-metal structure during construction factored axial thrust acting on a cross-section of a concrete structure (positive when compressive, negative when tensile), N per width b number of layers of reinforcement in a cage (n = 1 or 2) unfactored thrust in the wall of a soil-metal structure, kN/m

PPf

=

factored compressive strength of a corrugated metal section without buckling, kN/m

Ph

=

total horizontal earth load acting on a buried concrete pipe, kN per width b (see Clause 7.8.4.2.2)

R

=

radius of curvature of a conduit wall at the mid-depth of corrugations at a transverse section, mm; rise of a metal box structure as shown in Figure 7.6, m

RB , RL , = RU Rb

256

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=

radius of curvature of the invert of the cross-section of a pipe-arch November 2006

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Rc

=

R at crown, mm

Re

=

equivalent radius specified in Clause 7.6.3.2, mm

Canadian Highway Bridge Design Code

Rs

=

radius of curvature of the haunch of the cross-section of a pipe-arch

r

=

radius of gyration of corrugation profile, mm; radius to centreline of concrete pipe wall, mm

rs

=

radius of the inside reinforcement, mm

S

=

least transverse clear spacing between adjacent conduits, m

SM

=

fifth percentile flexural strength of a longitudinal connection per unit length, kN•m/m

Ss

=

fifth percentile axial strength of a longitudinal connection per unit length, kN/m

sv

=

circumferential spacing of stirrups, mm

s1

=

longitudinal spacing of circumferential reinforcement, mm

TC

=

additional thrust in the wall of a soil-metal structure due to construction live loads, kN/m

TD , TL

=

maximum thrust in a conduit wall per unit length due to unfactored dead and live loads, respectively, kN/m

TE

=

additional thrust in the wall of a soil-metal structure due to earthquake loading, kN/m

Tf

=

maximum thrust in a conduit wall due to factored loads per unit length, kN/m

tb

=

clear cover over reinforcement, mm

Vb

=

basic shear strength of a critical section of a concrete structure, where Mnu /Vu d = 3.0, N per width b

Vc

=

nominal shear strength provided by a concrete cross-section, N per width b

Vu

=

factored shear force acting on a concrete cross-section, N per width b

W

=

dead weight of the column of material above a conduit per unit length of conduit (see Figure 7.2), kN/m for soil-metal structures and kN per width b for concrete pipe and concrete box sections

We

=

total vertical earth load acting on a buried concrete pipe, kN per width b (see Clause 7.8.4.2.2)

wc

=

weight of a column of unit area of fill above a reference point at the top or on the sides of a buried concrete box section, kN/m2

αD αL γ θ

=

load factor for dead loads

=

load factor for live loads

=

unit weight of soil, kN/m3

=

skew angle of a conduit, degrees (see Table 7.1); orientation angle in a circular concrete pipe, degrees

θ0

=

angle of radial line from vertical demarking the upper and lower portions of a conduit wall in a soil-metal structure, radians

κ

=

crown moment coefficient used to calculate the crown and haunch bending moments in a metal box structure

λ λh

=

factor used in calculating K

=

factor used in the analysis of concrete buried structures in standard installations to account for the effect of soil-structure interaction on the horizontal soil pressures

λv

=

factor used in the analysis of concrete buried structures in standard installations to account for the effect of soil-structure interaction on the vertical soil pressures

ρ

=

σ σL

= =

reduction factor for buckling stress in metal conduit walls; ratio of reinforcement area to concrete area stress due to thrust in a conduit wall due to factored loads, MPa equivalent uniformly distributed pressure at the crown due to unfactored dispersed live load, kPa

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σh σv φc φh φ hc φj φs φt

= = = = = = = =

© Canadian Standards Association

horizontal earth pressure acting on the sides of a buried concrete box section, kPa vertical earth pressure acting at the top of a buried concrete box section, kPa resistance factor for concrete in compression, radial tension, and in shear resistance factor for plastic hinge for the completed structure resistance factor for plastic hinge during construction resistance factor for failure of connections resistance factor for flexural steel reinforcement resistance factor for compressive strength of soil-metal and metal box structures

7.4 Hydraulic design The following requirements shall apply to buried structures that are intended to convey water: (a) the hydraulic design of the conduit shall be in accordance with Clause 1.9; (b) the cut ends shall be as indicated in Table 7.1; and (c) for soil-metal structures and metal box structures, end treatments shall be provided in accordance with Clause 1.9.

Table 7.1 Requirements for cut ends (See Clause 7.4.) Typical view of installation Description of cut end Plan Section X-X 1. Square end with roadway parallel to transverse direction

Requirements None

X

X

2. Square end with roadway X skew to transverse direction

θ shall be less than 40°. For θ greater than 20°, the earth X q Contour grading

3. Skew end

pressure imbalance shall be accommodated by structural reinforcement of the conduit wall or by contour grading of the embankment slope. As for No. 2

X

X q

(Continued)

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Table 7.1 (Concluded) Typical view of installation Description of cut end Plan Section X-X 4. Square bevel with roadway parallel to X transverse direction

5. Square bevel with roadway skew to X transverse direction

X

b

Requirements b shall not be less than Dv /8. The ends shall be treated as a retaining structure and shall be designed in accordance with Section 6.

As for Nos. 3 and 4

X

b

q

6. Skew bevel

This cut end shall be avoided

X

X q

7.5 Structural design 7.5.1 Limit states For different types of buried structures, the specific limit states corresponding to general limit states shall be as specified in Table 7.2.

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Table 7.2 Specific limit states (See Clause 7.5.1.) General limit state

Type of structure

Specific limit state

Applicable clause

Ultimate limit state

Soil-metal with shallow corrugations

Compression failure Plastic hinge during construction Connection failure

7.6.3.2 7.6.3.3.1 7.6.3.4

Soil-metal with deep corrugations

Compression failure Plastic hinge Plastic hinge during construction Connection failure

7.6.3.2 7.6.3.3.2 7.6.3.3.1 7.6.3.4

Soil-metal

Deformation during construction

7.6.3.3.1

Metal box

Deformation during construction

7.7.5.2

Concrete

Maximum crack widths due to flexure

7.8.9.1

Soil-metal

—

—

Metal box

Stress range in conduit wall

7.7.3.1.5

Concrete

Stress range of the reinforcement

7.8.10

Serviceability limit state

Fatigue limit state

7.5.2 Load factors The load factors shall be as specified in Clause 3.5.1, except that the load factor for dead load for earth fill over concrete structures with curved bottom surfaces shall be increased by the installation factor specified in Clause 7.8.7.1(a). For earth pressure due to live loads, the factor for live loads shall be applied.

7.5.3 Material resistance factors The material resistance factors specified in Table 7.3 shall be used to calculate factored resistances for conduit walls.

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Table 7.3 Material resistance factors (See Clause 7.5.3.)

Type of structure

Component of resistance

Material resistance factor

Soil-metal with shallow corrugations

Compressive strength Plastic hinge during construction Connections

φ t = 0.80 φ hc = 0.90 φ j = 0.70

Soil-metal with deep corrugations

Compressive strength Plastic hinge Plastic hinge during construction Connections

φt φh φ hc φj

Metal box

Compressive Strength Plastic hinge Connections

φ t = 0.90 φ h = 0.90 φ j = 0.70

Precast concrete

Cold-drawn wire and welded wire fabric Flexural reinforcement — Hot-rolled bars Concrete (normal density)

φ s = 0.90 φ s = 0.90 φ c = 0.80

Cast-in-place concrete

Flexural steel reinforcement Concrete (normal density)

φ s = 0.90 φ c = 0.75

= = = =

0.80 0.85 0.90 0.70

7.5.4 Geotechnical considerations 7.5.4.1 Geotechnical investigation The feasibility of constructing buried structures and their approaches shall be established by a geotechnical investigation of the site unless knowledge of local subsurface conditions indicates that approach fills and cuts will remain stable during and after construction. Geotechnical investigation of the foundation shall be carried out to provide the information required for the design of the footings or the base of the structure.

7.5.4.2 Soil properties The soil properties used in the design of buried structures shall be as specified in Clause 7.6.2.3 for soil-metal structures, Clause 7.7.2.2 for metal box structures, and Clause 7.8.3.1 for concrete structures.

7.5.4.3 Camber Whether camber is needed shall be established by considering the flow-line gradient and estimating the maximum deformation of the foundation at the invert. If the maximum foundation deformation is to be compensated, the invert grade shall be cambered by an amount sufficient to prevent the development of a sag or back slope in the flow line.

7.5.4.4 Footings Footings shall be designed in accordance with Clause 6.7. Scour protection shall be provided in accordance with Clause 1.9.5. In the design of footings, consideration shall be given to resisting the horizontal reactions that develop in footings because of soil pressures on the conduit wall.

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7.5.4.5 Control of soil migration Where groundwater and soil characteristics can cause migration of soil fines into or out of foundation, bedding, sidefill, and backfill soils, methods to prevent migration shall be specified for the installation. These methods shall comprise the use of placed soils with filter gradation, the use of filter geotextiles, or other suitable means.

7.5.5 Seismic requirements 7.5.5.1 General Buried structures shall be designed to resist inertial forces associated with a seismic event having a 10% chance of being exceeded in 50 years. The vertical component of the earthquake acceleration ratio, AV , shall be two-thirds of the horizontal ground acceleration ratio, AH . AH shall be set equal to the zonal acceleration ratio specified in Clause 4.4.3. Amplification of these accelerations shall be considered where a significant thickness of less competent soil overlies rock or firm ground. Damage to the structure caused by excessive deformation of the soil, including the foundation soil, during a seismic event shall also be considered.

7.5.5.2 Seismic design of soil-metal structures For soil-metal structures, the additional thrust, TE , due to earthquake loading shall be calculated as follows: TE = TD AV In accordance with Clause 3.5.1, the total factored thrust, Tf , including the earthquake effects, shall be calculated as follows: Tf = α DTD + TE

7.5.5.3 Seismic design of metal box structures For metal box structures, the additional moment due to the effect of earthquake, ME , shall be calculated as follows: ME = MD AV The total factored moments, Mcf and Mhf , including the earthquake effects, shall be calculated as follows: Mcf =κ (α DMD + ME) Mhf = (1 – κ )(α DMD + ME) where αD is obtained from Clause 3.5.1.

7.5.5.4 Seismic design of concrete structures For concrete structures, the effects of earthquake loading shall be calculated in accordance with Clause 7.8.4.4.

7.5.6 Minimum clear spacing between conduits For multi-conduit structures, including soil-metal structures with shallow corrugations, the minimum clear spacing between adjacent conduits shall be not less than 1000 mm or one-tenth of the largest span; this requirement may be waived for concrete boxes with cement grout between the boxes. For multi-conduit soil-metal structures with deep corrugations, the minimum clear spacing between adjacent conduits shall be 1000 mm; if CLSM is used between the conduits, the minimum clear spacing may be reduced to 800 mm if the CLSM is poured to a height where its width is at least 800 mm.

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7.6 Soil-metal structures 7.6.1 General Clauses 7.6.2 to 7.6.7 apply to the structural design of steel or aluminum structures of circular, elliptic, pipe-arch, or pear-shaped pipes with a closed or arch configuration shown in Figure 7.1.

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Line through mid-height of corrugations (typical)

Dv

Dv

Dh

Dh

(a) Round pipe

(b) Horizontally elliptical pipe

0.5Dv

Dv

Dh

Dh

Spring line (typical)

(d) Pipe arch

(c) Vertically elliptical pipe

0.5Dv 0.5Dv

Dh

Dh

(e) Pear-shaped pipe

(f) Re-entrant arch

0.5Dv

Dv

Imaginary line

Dh

(g) Semi-circular arch

Dh

(h) Part-arch

Figure 7.1 Dh and Dv for various shapes of pipe (See Clauses 7.2, 7.6.1, 7.6.3.1.2, 7.6.3.2, and 7.6.4.1.)

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7.6.2 Structural materials 7.6.2.1 Structural metal plate Steel plates with both shallow and deep corrugations, and related components, shall satisfy the material and fabrication requirements of CSA G401. Aluminum plates and components shall satisfy the material and fabrication requirements of ASTM B 746/B 746M.

7.6.2.2 Corrugated steel pipe Corrugated steel pipe shall satisfy the material and fabrication requirements of CSA G401.

7.6.2.3 Soil materials Unless supported by in-situ or laboratory testing using recognized geotechnical engineering investigation and evaluation methods, the design shall be based on the soil properties specified in Table 7.4 for the various soils classified in Table 7.5. When the Standard Proctor densities are other than those specified in Table 7.5, linear interpolation shall be used to obtain the value of Es. In the absence of laboratory data, the value of Es for CLSM shall be assumed to be 30 MPa.

Table 7.4 Soil classifications (See Clauses 7.6.2.3 and 7.6.5.6.2 and Table 7.5.)

Soil group

Grain size

Soil types

Unified Soil Classification symbol*

I

Coarse

Well-graded gravel or sandy gravel Poorly graded gravel or sandy gravel Well-graded sand or gravelly sand Poorly graded sand or gravelly sand

GW GP SW SP

II

Medium

Clayey gravel or clayey-sandy gravel Clayey sand or clayey gravelly sand Silty sand or silty gravelly sand

GC SC SM

*According to ASTM D 2487.

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Table 7.5 Secant modulus of soil, Es , for various soils (See Clauses 7.2, 7.6.2.3, and 7.6.3.3.1.) Standard Proctor density, %†

Es , MPa

I

85 90 95 100

6 12 24 30

II

85 90 95 100

3 6 12 15

Soil group*

*See Table 7.4. †According to ASTM D 698.

7.6.3 Design criteria 7.6.3.1 Thrust 7.6.3.1.1 General The thrust, Tf , in the conduit wall due to factored live loads and dead loads shall be calculated for ULS Combination 1 of Table 3.1 as follows: Tf = α DTD + α LTL (1 + DLA) where TD and TL are calculated in accordance with Clauses 7.6.3.1.2 and 7.6.3.1.3, respectively, and the dynamic load allowance, DLA, is obtained from Clause 3.8.4.5.2.

7.6.3.1.2 Dead loads The thrust, TD , in the conduit walls due to the overfill shall be calculated as follows: TD = 0.5(1.0 – 0.1Cs)Af W where (a) Cs , the axial stiffness parameter, is calculated as follows:

Cs =

1000E sDv EA

(b) Af is obtained from Figure 7.2 for the relevant values of Dh /Dv and H/Dh , where Dh and Dv are as shown in Figure 7.1. For H/Dh smaller than 0.2, Af shall be obtained by graphical or numerical extrapolation, provided that the value of H is not smaller than the minimum depth of cover permitted by Clause 7.6.4.1; and (c) W is the weight of the column of earth and the pavement above the conduit, as shown in Figure 7.2.

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2.5

2.0

Dh /Dv = 0.6

1.5

Dh /Dv = 0.8 Dh /Dv = 1.0 Dh /Dv = 1.2 Dh /Dv = 1.4 Dh /Dv = 1.6

Af 1.0 W 0.5

0 0

1.0

2.0

3.0

H/Dh

Figure 7.2 Values of Af (See Clause 7.6.3.1.2.)

7.6.3.1.3 Live loads The thrust, TL , shall be assumed to be constant around the conduit wall, and its value shall be the lesser of TL = 0.5Dhσ L mf = 0.5ltσ L mf where (a) lt is the distance between the outermost axles, including the tire footprints, placed in accordance with Item (c)(i) plus 2H; (b) mf is the modification factor for multi-lane loading obtained from Clause 3.8.4.2, in accordance with the number of vehicles considered; and (c) the load case yielding the maximum value of σ Lmf governs. σ L is obtained as follows: (i) within the span length, position as many axles of the CL-W Truck or Trucks at the road surface above the conduit as would give the maximum total load; (ii) distribute the rectangular wheel loads through the fill down to the crown level at a slope of one vertically to one horizontally in the transverse direction of the conduit and two vertically to one horizontally in the longitudinal direction; and (iii) obtain the equivalent uniformly distributed pressure σ L by assuming that the total wheel loads considered in Item (i) are uniformly distributed over the rectangular area that encloses the individual rectangular areas obtained in Item (ii).

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7.6.3.2 Wall strength in compression For the purposes of this Clause, the conduit wall shall be divided into lower and upper zones separated from each other by two symmetrical radial lines with their centre at the centre of curvature of the arc at the crown, and with an angle θ 0, in radians, from the vertical calculated as follows:

⎡ EI ⎤ q 0 = 1.6 + 0.2 log ⎢ 3⎥ ⎢⎣ EmR ⎥⎦ At the ultimate limit state, the compressive stress, σ = Tf /A, shall not exceed the factored failure compressive stress, fb , calculated as follows: (a) for R ≤ Re :

(

)

2 ⎡ Fy KR ⎤ ⎢ ⎥ fb = ft Fm Fy − ⎢ 12Er 2 r ⎥ ⎥⎦ ⎣⎢

(b) for R > Re :

fb =

3ft rFmE ⎡ KR ⎤ ⎢⎣ r ⎥⎦

2

where (i) φ t for compressive strength is obtained from Clause 7.5.3; (ii) Fm = 1.0 for structures with single conduits

⎡ 0.3S ⎤ = ⎢0.85 + ⎥ ≤ 1.0 for structures with multiple conduits Dh ⎦ ⎣ where S is the least transverse clear spacing between adjacent conduits and Dh corresponds to the largest conduit in the structure and is as shown in Figure 7.1. The value of Fm shall be assumed to be 1.0 for upper portions of soil-metal structures with deep corrugations; (iii) Re =

r K

⎡ 6E r ⎤ ⎢ ⎥ ⎢⎣ Fy ⎥⎦

0.5

⎡ (H + H ′) ⎤ (iv) r = ⎢1000 Rc ⎥⎦ ⎣ (v)

⎡ EI ⎤ K = l⎢ 3⎥ ⎢⎣ EmR ⎥⎦

0.5

≤ 1.0

0.25

(vi) Em for the side and bottom portions of the conduit wall shall be the same as Es , but for the upper quarter of the conduit wall, it shall be calculated as follows:

⎡ ⎡ ⎤ Rc Em = E s ⎢1− ⎢ ⎥ ⎢ ⎣ Rc + 1000 [H + H ′] ⎦ ⎣

2⎤

⎥ ⎥ ⎦

When the conduit wall is supported by a combination of compacted soil and CLSM, the value of Em shall be based on the lower value of Es for the two materials; and

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(i)

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

 for the upper segments of the conduit wall of all structures except single-radius part-arches with rise-to-span ratios of less than 0.4 shall be calculated as follows: 0.25 ⎤ ⎡ ⎡ EI ⎤ ⎥ l = 1.22 ⎢1.0 + 1.6 ⎢ ⎥ ⎢ ⎥ EmRc3 ⎥⎦ ⎢ ⎣ ⎣ ⎦ For all other cases,  shall be 1.22.

7.6.3.3 Wall strength in bending and compression 7.6.3.3.1 Wall strength during construction For soil-metal structures with shallow or deep corrugations, the Plans shall specify the maximum axle load, Ac , of the construction equipment to be used above the conduit. The combined effects of the bending moment and axial thrust arising from the unfactored dead load and the specified construction equipment shall not exceed the factored plastic moment capacity of the section at all stages of construction, where the combined bending moment and axial thrust are calculated as follows: 2

⎡P ⎤ M ≤1 ⎢ ⎥ + MPf ⎣ PPf ⎦ where



P

= TD + TC (for Hc smaller than the minimum depth of cover required by Clause 7.6.4.1, P shall be assumed to be zero)

PPf

=  hc AFy

M=

M1 + MB + MC where M1

= kM1RB Dh3

MB

= – kM2RB Dh2Hc

MC =

kM3RLDhLc where kM1 = 0.0046 – 0.0010 log10(NF) for NF  5000 = 0 .0009 for NF > 5000 kM2 = 0.018 – 0.004 log10(NF) for NF  5000 = 0 .0032 for NF > 5000 kM3 = 0.120 – 0.018 log10(NF) for NF  100 000 = 0.0 30 for NF > 100 000 RB =

0.67 + 0.87[(Dv /2Dh) – 0.2] for 0.2  Dv /2Dh  0.35 = 0 .80 + 1.33[(Dv /2Dh) – 0.35] for 0.35 < Dv /2Dh  0.50 = Dv /Dh for Dv /2Dh > 0.5

RL Lc =

= [0.265 – 0.053 log10 (NF)]/(Hc /Dh)0.75 1.0 Ac /k4

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MPf

=  hc MP

M MPf

= absolute value of the ratio M / MPf

k4 shall be interpolated from the values specified in Table 7.6 and NF shall be calculated as follows: NF = Es(1000Dh)3/EI where Es is as specified in Table 7.5.

Table 7.6 Values for k 4 for calculating equivalent line loads (See Clauses 7.6.3.3.1, 7.6.3.3.2, and 7.7.3.1.3.) k4, m Depth of cover, m

Two wheels per axle

Four wheels per axle

Eight wheels per axle

0.3 0.6 0.9 1.5 2.1 3.0 4.6 6.1 9.1

1.3 1.6 2.1 3.7 4.4 4.9 6.7 8.5 12.2

1.5 2.0 2.7 3.8 4.4 4.9 6.7 8.5 12.2

2.6 2.8 3.2 4.1 4.5 4.9 6.7 8.5 12.2

7.6.3.3.2 Wall strength of completed structure For completed soil-metal structures with deep corrugations, the combined effects of the bending moment and axial thrust at the ultimate limit state shall not exceed the factored plastic moment capacity of the section, where the combined bending moment and axial thrust are calculated as follows: 2

⎡ Tf ⎤ Mf ≤ 1.0 ⎢ ⎥ + P M ⎣ Pf ⎦ Pf where Tf is calculated in accordance with Clause 7.6.3.1.1 and PPf , Mf , and MPf are calculated as follows: PPf = h AFy

Mf = a D M1 + a D MD + a LML (1+ DLA ) where M1 = kM1RB Dh3 MD = –kM2RB Dh2He where He = smaller of H and Dh /2 ML = kM 3RU Dh AL k4

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where kM1, kM2, kM3, and RB are obtained from the equations in Clause 7.6.3.3.1, AL is the weight of the second axle of the CL-W Truck, and k4 is obtained by interpolation from Table 7.6 for H up to 3.0 m. For H greater than 3.0 m, k4 shall be assumed to be 4.9 m. RU shall be calculated as follows:

0.265 − 0.053 log10 NF

RU = MPf

(H / Dh )0.75

≤ 1.0

= φh MP

Mf = absolute value of the ratio M / M f Pf MPf

7.6.3.4 Connection strength

The factored strength of longitudinal connections of conduit walls, φ j Ss , shall not be less than Tf , in which the fifth percentile strength, Ss , may be evaluated experimentally or obtained from Approved test data or published standards.

7.6.3.5 Maximum difference in plate thickness The difference in the thicknesses of the plates meeting at a longitudinal connection shall not exceed 1 mm if the thinner plate has a thickness of less than 3.1 mm, or exceed 1.5 mm if one of the plates has a thickness between 3.1 and 3.5 mm.

7.6.3.6 Radius of curvature The radius of curvature of the conduit wall, R, at any location shall not be less than 0.2Rc unless Approved. The ratio of the radii of mating plates at a longitudinal connection shall not be more than 8.

7.6.4 Additional design requirements 7.6.4.1 Minimum depth of cover For soil-metal structures with shallow corrugations, unless the conduit wall is designed using an Approved method other than one specified in this Section, the minimum depth of cover, Hmin , in metres, as shown in Figure 7.3, shall be the largest of (a) 0.6

⎡ Dh ⎤ ⎢ ⎥ ⎣ Dv ⎦

0.5

(b)

Dh 6

(c)

⎡D ⎤ 0 .4 ⎢ h ⎥ ⎣ Dv ⎦

2

where Dh and Dv are as shown in Figure 7.1. For soil-metal structures with deep corrugations, the minimum depth of cover shall be the smaller of 1.5 m and the minimum depth of cover for structures with shallow corrugations but the same conduit size.

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Roadway surface

H

Roadway surface

Hmin

H

Hmin

Neutral axis

Neutral axis

Single corrugated plate partially stiffened with sections of corrugated plate or other stiffeners

Single corrugated plate

Roadway surface

H

Hmin

Neutral axis

Continuously stiffened double corrugation

Figure 7.3 Depth of cover, H and Hmin, for soil-metal structures and metal box structures (See Clauses 7.2, 7.6.4.1, and 7.7.4.1.)

7.6.4.2 Foundation treatment for pipe-arches Foundations below the haunches of pipe-arches shall be treated as follows: (a) for dense to very dense cohesionless foundations and for stiff to hard cohesive foundations, no treatment shall be required; (b) for soft to firm cohesive foundations, reinforcement shall be provided as shown in Figure 7.4; and (c) for loose to compact cohesionless foundations, reinforcement shall be provided as shown in Figure 7.4 or by in-situ compaction. Geotechnical engineering judgment shall be used to determine the state of the foundation indicated in Items (a) to (c).

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CL

Trench reinforcement comprising Group I soils compacted to at least 95% Standard Proctor density 600 mm

Rs

Rb 300 mm

45°

45° 0.2Rb/Rs

Bedding

(metres)

Figure 7.4 Trench reinforcement for the foundation of pipe-arches (See Clause 7.6.4.2.)

7.6.4.3 Durability The durability of the structure shall be ensured for the specified design life with respect to the environment to which it will be exposed, in accordance with the relevant requirements of Section 2.

7.6.5 Construction 7.6.5.1 General The Plans shall specify the construction procedures and quality controls to be used.

7.6.5.2 Deformation during construction For all conduit shapes, the upward or downward crown deflection shall not exceed 2% of the rise unless Approved. Longitudinal and transverse alignment shall be maintained. If struts or cables are used to maintain the conduit shape during assembly or backfilling, they shall be removed before they restrict the downward movement of the crown.

7.6.5.3 Foundations When the foundation exhibits non-uniform characteristics, their effects shall be assessed and treated if necessary to ensure acceptable behaviour of the conduit.

7.6.5.4 Bedding The bedding shall consist of free-draining, well-graded granular material, and be preshaped in the transverse direction to accommodate the curved invert. A 200 mm thickness of the bedding layer that is in direct contact with the invert shall be left uncompacted.

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7.6.5.5 Assembly and erection Bolts at longitudinal connections shall be arranged in accordance with one of the two arrangements shown in Figure 7.5. When arrangement (b) is used, the bolts in the row closest to a visible edge of the mating plate shall be in the valleys and those in the other row shall be on the ridges. The torque on the bolts prior to backfilling shall be between 200 and 340 N•m. Before backfilling, at least 5% of the bolts used in each circumferential and longitudinal connection shall be tested after assembly. The test bolts shall be randomly selected and the installation shall be considered acceptable if the torque requirement is met in at least 90% of the bolts tested.

76 mm

76 mm

76 mm Ridge (typical)

Bolting arrangement (a)

76 mm

76 mm

76 mm

Visible edge (typical)

Valley (typical)

Bolting arrangement (b)

Figure 7.5 Longitudinal seam bolting arrangements (See Clause 7.6.5.5.)

7.6.5.6 Structural backfill 7.6.5.6.1 Extent of structural backfill The structural backfill in single-conduit structures under different fill conditions shall extend transversely at least the length specified in Table 7.7 on each side beyond the spring lines of the conduit, and vertically up to the minimum depth of cover required by Clause 7.6.4.1. For multi-conduit structures, structural backfill shall be provided between the adjacent conduits and shall extend transversely beyond the outer conduits at least the applicable distance specified in Table 7.7 for single-conduit structures. In the vertical direction, the structural backfill shall extend up to the minimum depth of cover required by Clause 7.6.4.1.

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Table 7.7 Minimum transverse distance of backfill in single-conduit soil-metal structures (See Clause 7.6.5.6.1.)

Backfill condition

Minimum transverse distance beyond each spring line, m

Structure constructed in trench in which the natural soil is as good as, or better than, the engineered soil

Smaller of 2.0 m and Dh /2

Structure constructed in trench in which the natural soil is poorer than the engineered soil

Smaller of 5.0 m and Dh /2, but not less than the smaller of rise and Dv /2

Structure constructed on embankment

Smaller of 5.0 m and Dh /2, but not less than the smaller of rise and Dv /2

7.6.5.6.2 Material for structural backfill The material for structural backfill shall be boulder free and shall be selected from the Group I or II soils specified in Table 7.4, with compaction corresponding to the modulus of soil stiffness used in the design. The backfill shall be placed and compacted in layers not exceeding 200 mm of compacted thickness, with each layer compacted to the required density prior to the addition of the next layer. The difference in levels of structural backfill on the two sides of a conduit at any transverse section shall not exceed 200 mm. The structural backfill within 300 mm of the conduit walls shall be free of stones exceeding 75 mm in any dimension. Heavy equipment shall not be allowed within 1 m of the conduit walls. The structural backfill adjacent to the conduit wall and to within the frost penetration depth shall be free of frost-susceptible soils. CLSM, if used, shall be considered part of the structural backfill.

7.6.6 Special features Soil-metal structures may be designed with structural or soil modifications or both. However, for compliance with the requirements of Clause 7.6, the properties of the affected components resulting from such modifications shall be determined from laboratory tests or field observations.

7.6.7 Site supervision and construction control The Plans shall specify (a) the requirements for testing of soil compaction; (b) that the supervision of the construction of soil-metal structures shall be undertaken by an Engineer who is experienced in the design and construction of such structures; and (c) the following procedures for inspection, as applicable: (i) for structures with spans between 3.0 and 6.0 m, that the work shall be inspected by the Engineer or a designated representative at the completion of the bedding, the erection of the conduit walls, the placement of the backfill under the haunches, the placement of the backfill up to the spring lines, the placement of the backfill up to the crown, and the placement of the backfill up to the level of minimum cover; (ii) for structures with spans between 6.0 and 8.0 m, that the inspections in Item (i) shall be conducted and that the construction shall be inspected daily by the Engineer or a designated representative until the backfill has reached the minimum depth of cover; and (iii) for structures with spans greater than 8 m or for which special techniques are used in accordance with Clause 7.6.6, that all stages of construction shall be inspected on a full-time basis by the Engineer. October 2011 (Replaces p. 275, November 2006)

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7.7 Metal box structures 

7.7.1 General The soil-structure interaction requirements of Clauses 7.7.2 to 7.7.7 shall apply to the design of steel and aluminum box structures with the dimensional limits shown in Figure 7.6 and a depth of cover up to 1.5 m. For spans greater than 8 m or rises greater than 3.2 m, the forces in the structure shall be calculated using rigorous methods of analysis that take into account the beneficial effects of soil-structure interaction. The rigorous methods of analysis may also be used for other metal box structures in lieu of the methods specified in Clauses 7.7.3.1.2 and 7.7.3.1.3. Stiffeners

Crown

Haunch

Sidewall

Rise, R

Span, Dh

Element

Minimum, m

Maximum, m

Rise, R

0.8

3.2

Span, Dh

2.7

8.0

Figure 7.6 Metal box structure dimensional limits (See Clauses 7.2 and 7.7.1.)

7.7.2 Structural materials 7.7.2.1 Structural metal plates Structural metal plates shall satisfy the requirements of Clause 7.6.2.1.

7.7.2.2 Soil materials The soil properties shall be determined in accordance with Clause 7.6.2.3.

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7.7.3 Design criteria 7.7.3.1 Design criteria for crown and haunches 7.7.3.1.1 General The factored crown and haunch bending moments, Mcf and Mhf , induced by factored dead and live loads shall be calculated for ULS Combination 1 of Table 3.1 as follows: Mcf = αDMcD + αLMcL(1 + DLA) Mhf = αDMhD + αLMhL(1 + DLA) where McD and MhD are calculated in accordance with Clause 7.7.3.1.2 and McL and MhL are calculated in accordance with Clause 7.7.3.1.3.

7.7.3.1.2 Dead loads The intensities of bending moments at the crown and the haunch due to dead loads, McD and MhD , shall be obtained as fractions of MD and calculated as follows: McD = κ MD MhD = (1 –κ )MD where

κ

= crown moment coefficient = 0.70 – 0.0328Dh

MD

=

d ⎤⎤ ⎡ ⎡ k1g Dh3 + k2g ⎢H − ⎢0.3 + c ⎥ ⎥ Dh2 2000 ⎦ ⎦ ⎣ ⎣

where k1

= 0.0053 – 0.00024 (3.28Dh – 12)

k2

= 0.053

7.7.3.1.3 Live loads The intensities of bending moments at the crown and the haunch due to live loads, McL and MhL , shall be obtained as fractions of ML and calculated as follows: McL = κ ML MhL = (1 – κ )kR ML where

κ

= crown moment coefficient = 0.70 – 0.0328Dh

kR

= 0.425H + 0.48 ≤ 1.0

ML

= C1k3 LL Dh where C1

= 1.0 for single axles =

0 .5 +

Dh ≤ 1.0 for multiple axles 15.24

0.08 k3

=

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⎡H ⎤ ⎢D ⎥ ⎣ h⎦

0.2

or Dh ≤ 6.0f m

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LL

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⎡⎣0.08 − 0.002 (3.28Dh − 20 ) ⎤⎦ ⎡H ⎤ ⎢D ⎥ ⎣ h⎦

0.2

for

m

Dh < 8 m

6

<

= AL /k4

where AL is the weight of a single axle of the CL-W Truck for Dh < 3.6 m, or the combined weight of the two closely spaced axles of the CL-W Truck for Dh ≥ 3.6 m, and k4 is a factor for calculating the line load, as specified in Table 7.6

7.7.3.1.4 Flexural capacity at the ultimate limit state At the ultimate limit state, neither the factored crown moment, Mcf , nor the factored haunch moment, Mhf , shall exceed the factored plastic moment, MPf , calculated as follows: MPf =φ h MP where

φh

= resistance factor for plastic hinge, as specified in Clause 7.5.3

MP

= plastic moment of the section

7.7.3.1.5 Fatigue resistance Longitudinal bolted seams shall not be located in the vicinity of the crown nor in areas of maximum live load moments at haunches. For spans greater than 8.0 m, consideration shall be given to the fatigue resistance of the bolted seams.

7.7.3.2 Design criteria for connections For conduit walls designed for only bending moments, the factored moment resistance of longitudinal connections, φ j SM, shall not be less than MPf . For sidewalls designed for both axial thrust and bending moments, the factored axial strength of longitudinal connections, φ jSs , shall not be less than Tf . The fifth percentile strengths, SM and Ss , may be evaluated experimentally or obtained from Approved test data or from published standards. Connections shall be designed at the ultimate limit state for the larger of (a) the calculated moment due to factored loads at the connection; and (b) 75% of the factored resistance of the member, φ h Mp.

7.7.4 Additional design considerations 7.7.4.1 Depth of cover The minimum depth of cover, Hmin , shown in Figure 7.3, shall be 0.3 m.

7.7.4.2 Durability The requirements of Clause 7.6.4.3 shall be satisfied.

7.7.5 Construction 7.7.5.1 Structural backfill 7.7.5.1.1 Extent of structural backfill The extent of structural backfill shall be as shown in Figure 7.7.

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Dh/2

Canadian Highway Bridge Design Code

Dh/2

0.30 m

Dh 1.0 m

1.0 m

Figure 7.7 Minimum extent of structural backfill for metal box structures (See Clause 7.7.5.1.1.)

7.7.5.1.2 Materials for structural backfill The materials for structural backfill shall satisfy the requirements of Clause 7.6.5.6.2.

7.7.5.2 Deformation during construction The upward or downward crown deflection during construction shall not exceed 1% of the span unless a greater deflection is Approved.

7.7.6 Special features The use of special features to improve the structural performance, and their effects on the requirements of Clauses 7.7.1 to 7.7.5, shall be subject to Approval.

7.7.7 Site supervision and construction control The site supervision and construction control of metal box structures shall be in accordance with Clause 7.6.7.

7.8 Reinforced concrete buried structures 7.8.1 Standards for structural components For reinforced concrete buried structures, the materials, methods of material testing, and construction practices for concrete shall be in accordance with Clause 8.4.1.1, and those for reinforcing bars and meshes with Clauses 8.4.2.1.1 and 8.4.2.2. In addition, the manufacturing Standards applicable to generic precast buried concrete structures shall be as specified in Table 7.8. For precast segmental structures, including non-standard arches and three-sided boxes with flat and curved tops (some of which can be proprietary products), the manufacturing Standards shall be those specified in Table 7.8 (adapted as necessary) and such other Standards as are applicable (also adapted as necessary).

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Table 7.8 Standards for precast buried concrete structures (See Clause 7.8.1.) Category of structure

Standard

Arch pipe Box sections Circular pipe Elliptical pipe Manholes and catchbasins

ASTM C 506M ASTM C 1433M or ASTM PS 62 CAN/CSA-A257.1 and CAN/CSA-A257.2 ASTM C 507M CAN/CSA-A257 Series

7.8.2 Standards for joint gaskets for precast concrete units Elastomeric gaskets used for sealing precast concrete units shall comply with CAN/CSA-A257.3.

7.8.3 Installation criteria 7.8.3.1 Backfill soils The extent of the soil included in the design of the structure shall be as specified in Clauses 7.8.3.5 and 7.8.3.6 for the applicable structure, with the classification of placed soils being as specified in Table 7.9.

Table 7.9 Classification of placed soils (See Clauses 7.8.3.1 and 7.8.3.5.2.) Soil group*

Description

Unified Soil Classification symbols†

I

Sand and gravel

SW, SP, GW, GP

II

Sandy silt

GM; SM; ML; GC and SC with less than 20% passing #200 sieve

III

Silty clay

CL; MH; GC and SC with more than 20% passing #200 sieve

*See Table 7.4. †According to ASTM D 2487.

7.8.3.2 Minimum depth of cover for structures with curved tops For concrete structures with curved-top segments designed in accordance with the empirical methods specified in this Section, the minimum depth of cover shall be as follows: (a) for structures below unpaved and flexible pavements: the greater of 300 mm and one-fourth the radius of curvature of the top segment; and (b) for structures below rigid pavements: 150 mm plus the thickness of the pavement.

7.8.3.3 Compaction Unless otherwise Approved, the measure of the compaction of placed soils shall be the Standard or Modified Proctor density in accordance with ASTM D 698 and ASTM D 1557, respectively.

7.8.3.4 Frost penetration For concrete structures in climates where frost can penetrate embedment soils, frost-susceptible soils shall not be used adjacent to the conduit wall within the depth of frost penetration unless, for design purposes, they are considered to be uncompacted.

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7.8.3.5 Standard installations for circular precast concrete pipes 7.8.3.5.1 General Four types of installation for circular precast concrete pipes are specified in Table 7.10. Pipes in these installations shall be analyzed in accordance with the empirical method specified in Clause 7.8.5.2. The extent of the different zones of the backfill shall be as shown in Figures 7.8. and 7.9.

Overfill zone (soil group I, II, or III)

Do/6 (min.)

H

Do

Do (min.)

Crown Haunch zone

Obvert

Lower sidefill zone

Di

Invert Bottom

Bedding

Outer bedding zone material and compaction each side — same requirements as haunch

Do /3

Middle bedding zone loosely placed uncompacted granular, except Type 4

Foundation or subgrade (existing soil or compacted fill)

Figure 7.8 Terminology and standard installations for circular precast concrete pipes on embankments (See Clauses 7.2, 7.8.3.5.1, 7.8.3.5.2, and 7.8.15.6.1.)

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Overfill zone (soil group I, II, or III) Excavation line, as required

H

Do/6 (min.)

Do

Do (min.)

Haunch zone This in-situ soil shall be considered as lower sidefill zone for the calculation of soil properties

Di Bedding

Outer bedding zone material and compaction each side — same requirements as haunch

Do/3

Middle bedding zone loosely placed uncompacted granular, except Type 4

Foundation

Figure 7.9 Terminology and standard installations for circular precast concrete pipes in trenches (See Clauses 7.2, 7.8.3.5.1, 7.8.3.5.2, and 7.8.15.6.1.)

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Table 7.10 Soils and compaction requirements for standard installations for circular precast concrete pipes (See Clauses 7.8.3.5.1 and 7.8.3.5.2.) Equivalent minimum Standard Proctor compaction Installation type

Minimum bedding thickness

Soil group

Haunch and outer bedding zones

Lower sidefill zone

Do / 12, but not less than 150 mm

I II III

95% Not permitted Not permitted

90% 95% 100%

Do / 24 , but not less than 75 mm

Do / 12, but not less than 150 mm

I II III

90% 95% Not permitted

85% 90% 95%

C3

Do / 24, but not less than 75 mm

Do / 12, but not less than 150 mm

I II III

85% 90% 95%

85% 90% 95%

C4

No bedding needed

Do / 12, but not less than 150 mm

I

No compaction needed No compaction needed 85%

Soil foundations

Rock foundations

C1

Do / 24, but not less than 75 mm

C2

II III

No compaction needed No compaction needed 85%

7.8.3.5.2 Additional requirements for standard trench and embankment installations The following additional requirements shall apply to standard trench and embankment installations: (a) the soil in the haunch zone, as shown in Figures 7.8 and 7.9, shall be one of the engineered soil groups identified in Table 7.9; (b) the soil in the lower sidefill zones and in the overfill zone, as shown in Figures 7.8 and 7.9, shall be (i) engineered soil in accordance with Table 7.9 and meet the requirements of Table 7.10; or (ii) an in-situ soil of equivalent stiffness; (c) the extent of bedding shall be as shown in Figures 7.8 and 7.9; (d) the properties of the soil within a distance Do measured laterally from the conduit wall shall be used for the design of the structure; and (e) the soil in the outer bedding, haunch, and lower sidefill zones shall be compacted to at least the same degree as the soil in the overfill zone.

7.8.3.5.3 Additional requirements for standard trench installations only The following additional requirements shall apply to standard trench installations only: (a) the trench width shall be sufficient to permit the proper use of equipment for compacting the backfill in the haunch zone; and (b) in-situ soils that have cuts from 0 to 10° of vertical shall be considered equivalent to Group I soils compacted to 90% of Standard Proctor density.

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7.8.3.6 Standard installations for precast and cast-in-place concrete boxes 7.8.3.6.1 General Two types of installation for precast and cast-in-place concrete boxes are specified in Table 7.11. Box structures in these installations shall be analyzed in accordance with the empirical method specified in Clause 7.8.5.3. The extent of the different zones of the backfill shall be as shown in Figures 7.10 and 7.11.

Table 7.11 Soils and compaction requirements for standard installations for concrete boxes (See Clauses 7.8.3.6.1 and Figures 7.10 and 7.11.)

Soil group

Equivalent minimum Standard Proctor compaction in sidefill and outer bedding zones

B1

I II III

90% 95% Not permitted

B2

I II III

80% 85% 95%

Installation type

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Overfill (soil group I, II, or III)

Lho /2 (min.)

Sidefill (see Table 7.11)

Lho /2 (min.)

Lho

Lhi

Lvo Lvi

Bedding 50 mm (min.)

Outer bedding material and compaction each side — same requirements as sidefill

Lho/3

Middle bedding loosely placed uncompacted bedding for Type B1

Figure 7.10 Standard installations for concrete box sections on embankments (See Clauses 7.2, 7.8.3.6.1, and 7.8.15.6.1.)

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Overfill (soil group I, II, or III)

Lho/6 (min.)

Excavation line, as required

Lho

Lho (min.)

Sidefill (see Table 7.11) This in-situ soil shall be considered as lower sidefill zone for the calculation of soil properties

Bedding 50 mm (min.)

Outer bedding material and compaction each side — same requirements as sidefill

Lho/3

Middle bedding loosely placed uncompacted bedding for Type B1

Figure 7.11 Standard installations for concrete box sections in trenches (See Clauses 7.2, 7.8.3.6.1, and 7.8.15.6.1.)

7.8.3.6.2 Additional requirements for standard trench and embankment installations The following additional requirements shall apply to standard trench and embankment installations: (a) the soil in the outer bedding and sidefill zones shall be compacted to at least the same degree as the soil in the overfill zone; and (b) the soil in the middle bedding zone shall be of the same material as that in the outer bedding zone, but shall not be compacted.

7.8.3.6.3 Additional requirements for standard trench installations only The following additional requirements shall apply to standard trench installations only: (a) the trench width shall be sufficient to permit the proper use of equipment for compacting the backfill; and (b) in-situ soils that have cuts from 0 to 10° of vertical shall be considered equivalent to Group I soils compacted to 90% of Standard Proctor density.

7.8.3.7 Non-standard installations Buried concrete structures may be placed in non-standard installations if they are designed in accordance with Approved methods based on soil-structure interaction.

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7.8.4 Loads and load combinations 7.8.4.1 Load combinations Consistent with the load combinations of Section 3, the following load combinations shall be considered for the ultimate limit state design: (a) self-weight of the structure, earth load, live load, and water load, together with the minimum value in the range of lateral earth pressure; (b) the combination specified in Item (a), except with the maximum value in the range of lateral earth pressure; (c) the combination specified in Item (a), except that the live load is adjacent to structures with vertical sides instead of over the structure; and (d) self-weight of the structure, earth, and earthquake load.

7.8.4.2 Earth load 7.8.4.2.1 General Earth load shall be determined from the unit weight and height of overfill soil over the top of the structure and its effects shall be determined by an analysis of soil-structure interaction based on the characteristics of the installation.

7.8.4.2.2 Earth load on circular pipe in standard installations The total vertical earth load acting on a buried pipe, We , shall be obtained by multiplying the weight of the column of earth over the outside diameter of the pipe, W, by the vertical arching factor, λ v , for the specified standard installation type. The total horizontal earth load acting on the buried pipe, Ph , shall be obtained by multiplying the weight of the column of earth over the outside diameter of the pipe, W, by the horizontal arching factor, λ h , for the specified standard installation type. The values of λ v and λ h for each standard installation type shall be as specified in Table 7.12.

Table 7.12 Vertical and horizontal arching factors for circular concrete pipes in standard installations (See Clauses 7.8.4.2.2, 7.8.5.2.3, and 7.8.5.2.4.)

Installation type

Vertical arching factor, λ v

Horizontal arching factor, λ h

C1 C2 C3 C4

1.35 1.40 1.40 1.45

0.45 0.40 0.37 0.30

7.8.4.2.3 Earth load on box sections in standard installations The vertical and horizontal earth loads shall be determined by multiplying the weight of earth over the top of the box section by the vertical and horizontal arching factors, λ v and λ h , respectively, as specified in Table 7.13.

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Table 7.13 Vertical and horizontal arching factors for box sections in standard installations (See Clauses 7.8.4.2.3 and 7.8.5.3.2.)

Installation type

Vertical arching factor, λ v

B1 B2

Horizontal arching factor, λ h Minimum

Maximum

1.20

0.30

0.50

1.35

0.25

0.50

7.8.4.3 Live load Live load shall be the applicable CL-W Truck load specified in Section 3 and shall include the dynamic load allowance specified in Clause 3.8.4.5.2.

7.8.4.4 Earthquake loads The additional force effects due to earthquake loads shall be accounted for by multiplying the force effects due to self-weight and earth load, obtained in accordance with Clauses 7.8.6 and 7.8.7.1, by the vertical acceleration ratio, AV , specified in Clause 7.5.5.1.

7.8.5 Earth pressure distribution from loads 7.8.5.1 General Earth pressures acting on buried concrete structures shall be determined from a soil-structure interaction analysis for the soil/pipe installation. Earth pressure distributions developed for circular pipe and box sections in standard installations shall be as specified in Clauses 7.8.5.2 and 7.8.5.3, respectively.

7.8.5.2 Circular pipe in standard installations 7.8.5.2.1 Pipe weight For the analysis of the effects of its self-weight, the pipe shall be assumed to be supported at the bottom over an arc length subtending an angle of 30° centred at the pipe invert. A radial pressure distribution at the pipe support shall be assumed to be sinusoidal, with the peak at the centre and zero at the edges.

7.8.5.2.2 Earth load For the analysis of horizontal and vertical effects of earth load, a unit length of pipe shall be assumed to be subjected to the earth pressure distribution shown in Figure 7.12. The various components of the Figure 7.12 force diagram shall be obtained by multiplying the earth load, W, by the factors specified in Table 7.14 for the applicable standard installation type. The pressure distributions shall be taken to vary linearly or parabolically and the magnitude of their components shall be obtained by multiplying W /Do by the relevant factors specified in Table 7.15 for the relevant standard installation type. The locations of the forces and peak values of pressures shall be determined by multiplying the length factors specified in Table 7.16 by Do.

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0.5F3

0.5F3

F6

F6

F5 F4

Do = 1 c

d

uc

vd

e

F5 F4

f

0.5F2

0.5F2 F1

Figure 7.12 Earth pressure distribution for standard installations of circular concrete pipes (force diagram) (See Clauses 7.8.5.2.2–7.8.5.2.4.)

Table 7.14 Force factors for earth loads (See Clause 7.8.5.2.2.) Installation type

F1

F2

F3

F4

F5

F6

C1 C2 C3 C4

0.62 0.85 1.05 1.45

0.73 0.55 0.35 0.00

1.35 1.40 1.40 1.45

0.19 0.15 0.10 0.00

0.08 0.08 0.10 0.11

0.18 0.17 0.17 0.19

Table 7.15 Earth pressure factors (See Clause 7.8.5.2.3 and 7.8.5.2.4.)

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Installation Type

pa

pb

pc

pd

C1 C2 C3 C4

1.40 1.45 1.45 1.45

0.40 0.40 0.36 0.30

2.87 3.51 4.26 4.58

1.85 1.48 0.99 0.00

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Table 7.16 Length factors for earth pressures (See Clause 7.8.5.2.2.) Installation type

lc

le

lf

u

v

C1 C2 C3 C4

0.18 0.19 0.20 0.25

0.08 0.10 0.12 0.00

0.05 0.05 0.05 —

0.80 0.82 0.85 0.90

0.80 0.70 0.60 —

Note: ld = 0.5 – lc – le .

7.8.5.2.3 Water loads For determining the effects of water loads, a unit length of the pipe shall be assumed to be flowing full, and the non-dimensional earth pressure distribution on the bottom of the pipe shall be as shown in Figure 7.12 and specified in Table 7.15. To obtain the actual bottom pressures for an installation type, the force ratios F1 and F2 shall be multiplied by the total weight of water divided by the applicable vertical arching factor, λ v , obtained from Table 7.12. Lateral pressure shall be neglected.

7.8.5.2.4 Live load For the analysis of live load effects, a unit length of pipe shall be assumed to be subjected to a uniform pressure at the top of the pipe, determined by distributing the applied wheel load through the pavement (if any) and earth above the pipe over a distance specified in Clause 6.9.6. The reacting earth pressure on the bottom of the pipe shall be determined using the non-dimensional pressure distribution on the bottom of the pipe shown in Figure 7.12 and specified in Table 7.15. To obtain the actual bottom pressures for an installation type, the force ratios F1 and F2 shall be multiplied by the total live load acting on the pipe divided by the applicable vertical arching factor, λ v , obtained from Table 7.12. Lateral pressure shall be neglected.

7.8.5.3 Box sections in standard installations 7.8.5.3.1 Box weight For the analysis of the effects of its self-weight, the concrete box shall be assumed to be uniformly supported over its entire width.

7.8.5.3.2 Earth load

Earth pressures on box sections shall be assumed to be uniformly distributed vertical pressures, σ v , and linearly varying horizontal pressures, σ h , calculated as follows: (a) σ v = λ v wc (b) σ h = λ h wc where the earth pressure arching factors, λ v and λ h , are as specified in Table 7.13 for the two standard installations, and wc is the weight of a column of unit area of fill above the reference point. The maximum and minimum values of λ h shall be used to obtain the maximum positive and negative moments in the conduit walls. The reaction pressure on the bottom of the box shall be assumed to be uniformly distributed.

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7.8.5.3.3 Live load Earth pressure on the buried box section due to live load shall be considered to be uniformly distributed above the box section over an area determined by distribution of the applied live load through the pavement (if any) and earth above the pipe as specified in Clause 6.9.6. The reacting earth pressure on the bottom of the box shall be assumed to be uniformly distributed. Lateral pressure due to live load for the load combinations specified in Items (a) and (b) of Clause 7.8.4.1 shall be neglected. For the load combination specified in Item (c) of Clause 7.8.4.1, lateral pressure from an approaching wheel load shall be taken as shown in Figure 7.13. No live load on box for this load case

Approaching wheel load H pt = 10.2 kPa H

pt

Maximum pt = 38.3 kPa

Lvo

10.2 pb = kPa Lvo +H 1000

pb

Figure 7.13 Lateral earth loads and pressure distribution on concrete box sections due to approaching wheel loads (See Clause 7.8.5.3.3.)

7.8.6 Analysis An analysis for moments, thrusts, and shears shall be performed for buried concrete structures subject to the load combinations of Clause 7.8.4. For pipe and box structures, the earth pressure distributions shall be as specified in Clause 7.8.5.

7.8.7 Ultimate limit state 7.8.7.1 Additional factors The load factors for self-weight, earth, water, live, and earthquake loads shall be in accordance with Clause 7.5.2. In addition, the following requirements shall be satisfied: (a) An installation factor of 1.1, in addition to the other load factors, shall be included in the multiplication to obtain the factored load effects due to earth load on the pipe and conduit shapes with curved bottoms. (b) In the calculation of flexural tension, shear, and radial tension, where compressive thrust reduces the required strength for combined bending and thrust compared to bending alone, the load factors for compressive thrust caused by self-weight load, earth load, and live load shall be taken as 1.0 in lieu of the minimum load factors specified in Table 3.2. November 2006

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7.8.7.2 Resistance factors Resistance factors shall be as specified in Clause 7.5.3.

7.8.8 Strength design 7.8.8.1 Flexure 7.8.8.1.1 General The proportioning of conduit walls subject to combined flexure and axial compression shall be in accordance with Clause 8.8. In addition, the following shall apply at locations where any flexural reinforcement is terminated: (a) The minimum area of the remaining reinforcement shall have sufficient development length. (b) At least 33% of the maximum inside reinforcement in slabs and walls shall be continuous in each component of a structure. At least 25% of the maximum outside reinforcement in slabs and walls shall be continuous in each component of a structure. (c) The design yield strength, fy , shall not exceed 500 MPa for bars or 550 MPa for welded wire fabric if the design yield strength is not greater than 85% of the breaking strength. (d) The concrete strength, fc’, used in calculating design resistances shall not exceed 45 MPa.

7.8.8.1.2 Maximum flexural reinforcement without stirrups or ties When stirrups or ties are not used, Asi shall not exceed the following limits, which are based on considerations of radial tensile strength:

⎡f ⎤ F Asi ≤ 0.111brs fc′ ⎢ c ⎥ rt ⎣ fs ⎦ fy where =

Frt

(3600 − Di )2

+ 0.80 for 1800 mm < Di ≤ 3600 mm 16.8 × 106 = 0.8 for Di > 3600 mm

7.8.8.2 Design for shear 7.8.8.2.1 Circular, elliptical, and arch pipe without stirrups or ties When stirrups or ties are not used, the conduit wall shall be designed so that for each region requiring flexural tensile reinforcement at the inside or outside of the wall, the shear strength of the concrete, Vc , shall be greater than the factored shear force, Vu , at any section in each region. Mnu shall be calculated as follows: Mnu = Mu − Nu

( 4h − d ) 8

At sections where Mnu /Vuφ c d is greater than or equal to 3.0, the following value of Vc shall apply: Vc = Vb where Vb

292

=

⎡F F ⎤ 0.083bfc d fc′ (1.1+ 63r ) ⎢ d N ⎥ ⎣ Fc ⎦

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where fc‘

≤ 45 MPa

ρ

=

As < 0.02 bd

Fd

=

0.8 +

FN

= 1+

Nu ≥ 1.0 for compressive thrust (Nu positive) 14bh

= 1+

Nu ≤ 1.0 for tensile thrust (Nu negative) 3.5bh

= 1+

d for tension on the inside of the pipe 2r

= 1−

d for tension on the outside of the pipe 2r

Fc

41 ≤ 1.3 d

At sections where Mnu /Vuφ c d is less than 3.0, the following value of Vc shall apply:

4Vb ≤ 0.25fc bd fc′ Vc = Mnu +1 Vu d where Vb is as specified in this Clause.

7.8.8.2.2 Box sections and segmental structures without stirrups or ties 7.8.8.2.2.1 For concrete box culverts, the shear strength of the slab need not be checked if the following conditions are satisfied: (a) the centre-to-centre spacing of the vertical walls is less than or equal to 4.0 m; (b) the slab thickness is greater than or equal to 175 mm; and (c) the reinforcement ratio of bottom steel bars in the direction of the span is not less than 0.3%. When stirrups or ties are not used in box sections and segmental structures, and the conditions specified in Items (a) to (c) are not satisfied, the shear strength shall be determined at critical sections, taking into consideration the fact that sections located less than a distance d from the face of a support can be designed for the same shear, Vu , as that calculated at a distance d, if the support reaction, in the direction of the applied shear, introduces compression into the end regions of the member and no concentrated load occurs between the face of the support and the location of the critical section at d. Also, the tips of haunches with an inclination 45° or steeper shall be taken as the face of the support instead of the face of the sidewall.

7.8.8.2.2.2 The shear strength specified in Clause 7.8.8.2.2.1 shall be determined (a) in accordance with Clauses 8.9.3 and 8.9.4, except that for sections within 2d of the face of the support, Clause 8.10 shall be used instead of Clause 8.9; or (b) using an alternative procedure for single-cell box sections, for which the shear strength without stirrups or ties is taken in accordance with Clause 7.8.8.2.1, with Fc = 1.0, provided that the following conditions are satisfied: (i) the load distribution over the top and bottom slabs is uniform;

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(ii) the combined area of inner and outer reinforcement at d f rom support satisfies

Asi + Aso ≥

2Vu fs fy

where Vu is taken at a distance d from the support; (iii) the area of the reinforcement that resists tension produced by the bending moment at a distance d from the face of the support or haunch tip is calculated as follows:

Mu ⎤ ⎡ ⎢⎣0.5Vu + 0.9d ⎥⎦ As ≥ fs fy where Mu is taken at a distance d from the support or the tip of the haunch; and (iv) inner and outer reinforcement extend into the support wall or haunch with sufficient anchorage to develop the minimum required reinforcement areas in Items (ii) and (iii) and the outer reinforcement extends beyond 2d from the support, with sufficient anchorage to develop the minimum required outer reinforcement area.

7.8.8.2.3 Stirrup reinforcement for shear and radial tension If Vc is less than Vu at any section, stirrups shall be designed so that

Avs =

(Mu − 0.45Nu fc d ) ⎤ 1.1sv ⎡ ⎢(Vu Fc − Vc ) + ⎥ fv fc d ⎣ rs ⎦

where ≤

Vc

0.166fc bd fc′ = maximum strength that can be developed by the stirrups and is less than or equal to fy

fv

The following requirements shall also apply: (a) For pipes, the maximum spacing between the stirrups in the circumferential direction shall be sv ≤ 0.75φ c d. (b) For box and segmental structures, the maximum spacing between the stirrups in the circumferential direction shall be as specified in Clause 8.14.6. (c) For curved members, the maximum spacing between the stirrups in the longitudinal direction shall be the same as the spacing of the circumferential reinforcing wires or bars. (d) For straight members, the maximum spacing between the stirrups in the longitudinal direction shall be 1.5d. (e) Stirrups shall be provided in all locations where Vu is greater than Vc plus an additional minimum distance equal to the conduit wall thickness, h, beyond these locations. (f) When stirrups are required for shear or radial tension at the invert or the crown regions of curved conduit walls, they shall extend on each side beyond the calculated arc length requiring stirrups for an additional arc length of at least 0.5lθ , where

q =

πq (Di 6 + 2tb ) + h 180

If stirrups are also needed at the spring line regions, as can occur in very-high-loading conditions, they shall be spaced at sv and shall extend around the entire circumference. (g) The stirrups required at a point of critical shear in a region adjacent to a support shall be extended to the face of the support members. In box sections and other structures with 45° or steeper haunches, the stirrups used in the slab shall be extended to a point one-third the slab thickness, h, from the start of the haunch toward the support. Stirrup anchorage shall be in accordance with Clause 8.15.1.5 or as demonstrated by Approved tests.

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7.8.9 Serviceability limit state 7.8.9.1 Control of cracking The crack-control requirements of Clauses 8.12.2 and 8.12.3 shall be satisfied, except for structures with principal reinforcement consisting of 10M bars or smaller spaced at intervals of 100 mm or less, for which the crack-control factor, Fcr , calculated as follows, shall not exceed 0.85:

Fcr =

0.083C1 h 2 fc′ ⎤ B1 ⎡ ⎢fs − ⎥ 5250fs ⎢⎣ rd 2 ⎥⎦

where B1

=

⎡ 25tb s1 ⎤ ⎢ 2n ⎥ ⎣ ⎦

1/ 3

where (a) tb ≥ 25 mm and tb ≤ 0.33h or 75 mm, whichever is less; (b) 50 mm ≤ s1 ≤ 102 mm; and (c) n = 1 when tension reinforcement is a single layer and n = 2 when tension reinforcement is made of multiple layers. The crack-control coefficient, C 1, for different types of reinforcement shall be as specified in Table 7.17.

Table 7.17 Crack-control coefficient, C1 (See Clause 7.8.9.1.) Type of reinforcement

C1

Smooth wire or plain bars

1.0

Welded smooth wire fabric with 200 mm maximum spacing of longitudinal wires, deformed wire, or welded deformed wire fabric

1.5

Deformed bars or any reinforcement with stirrups anchored to it

1.9

7.8.9.2 Corrosion protection Primary corrosion protection of reinforcement shall be provided by controlling crack widths in accordance with Clause 7.8.9.1 and by providing sufficient concrete cover in accordance with Clause 8.11.2.2.

7.8.10 Fatigue limit state Reinforcement stress ranges in the top slabs of box sections and similar structures with depths of cover less than 0.6 m shall comply with the requirements of Clause 8.5.3.1, except that cross-wire welds in welded wire fabric reinforcement shall not be deemed to be tack welds.

7.8.11 Minimum reinforcement 7.8.11.1 Parallel to span Each of the inside and outside layers of reinforcement parallel to the span shall provide a minimum area of reinforcement of 0.002bh, but not less than that required for shrinkage and temperature in accordance with Clause 7.8.11.2.

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7.8.11.2 Perpendicular to span Reinforcement for shrinkage and temperature effects normal to the principal reinforcement shall be provided in conduits where principal reinforcement extends in one direction only. The minimum area and maximum spacing of shrinkage and temperature reinforcement shall be in accordance with Table 7.18.

Table 7.18 Shrinkage and temperature reinforcement (See Clauses 7.8.11.2 and 7.8.12.2.)

Type of structure Precast concrete, maximum length 6 m Other

Minimum area of reinforcement, mm2/m Inside face

Outside face

Maximum spacing, mm

Above principal reinforcement on inside face

300

—

250

2

Near each face

300

300

250

≥ 0.6

2

Near each face

500

250

250

< 0.6

2

Near each face

500

500

250

Minimum depth of earth cover, m

Number of layers

≥ 0.6

1

< 0.6

Location

7.8.12 Distribution reinforcement 7.8.12.1 Design of reinforcement The following requirements for design of reinforcement shall apply: (a) The top slabs of box sections, and other structures with flat top slabs with a depth of cover less than 0.6 m, shall be provided with distribution reinforcement in accordance with Clause 8.18.7, to be placed near the inside of the bottom face of the slab. (b) Where not overlaid by a cast-in-place reinforced concrete slab, top slabs of precast concrete box sections, and other precast concrete structures with flat top slabs with a depth of cover less than 0.6 m, shall have additional distribution reinforcement equal to at least one-half the amount of distribution reinforcement required by Item (a), placed near the outside of the top face of the slab. Note: The area of shrinkage and temperature reinforcement required by Clause 7.8.11.2 may also be used to satisfy the requirements for distribution reinforcement in this Clause.

7.8.12.2 Minimum area of distribution reinforcement The minimum area of distribution reinforcement perpendicular to the principal transverse reinforcement shall be as specified in Table 7.18.

7.8.13 Details of the reinforcement 7.8.13.1 General Subject to Clause 7.8.13.2, the details of the reinforcement shall be in accordance with Clauses 8.14 and 8.15.

7.8.13.2 Precast concrete pipe and box sections The following details of the reinforcement shall be in accordance with the requirements specified in Appendix A of ASCE 15: (a) development of principal reinforcement for welded splices, lapped splices, and anchorage at cut-offs;

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(b) anchorage of stirrups located in regions where the outside reinforcement is subjected to flexural tension; and (c) joint reinforcement.

7.8.14 Joint shear for top slab of precast concrete box sections with depth of cover less than 0.6 m The top slab joint between adjacent precast concrete units shall be capable of transferring a minimum unfactored shear load of 60 000 N/m unless the joints in the top slab are covered by a cast-in-place reinforced concrete slab at least 150 mm thick. If individual shear connectors are used, their centre-to-centre spacing shall not be greater than 800 mm, with a minimum of two shear connectors per joint.

7.8.15 Construction 7.8.15.1 Foundations 7.8.15.1.1 General The foundation shall comprise moderately firm to hard in-situ soil, stabilized soil, or compacted fill materials.

7.8.15.1.2 Soft soil When unsuitable or unstable material is encountered, the foundation shall be stabilized so as to meet the installation design requirements of Clause 7.8.3. Foundation soils for a minimum of one conduit inside width on each side of the conduit shall be at least as stiff as the foundation soil below the conduit.

7.8.15.1.3 Rock Precast concrete pipe and other conduits with curved bottoms shall not be placed directly on a rock foundation. For pipes, the minimum bedding thickness over rock shall be the greater of 150 mm or Do /12. Precast concrete box sections and other conduits with flat bottoms shall be placed on a flat granular bedding at least 75 mm thick.

7.8.15.1.4 Control of water Groundwater levels shall be controlled to avoid disturbing fine sand or silty soil foundations and to comply with the installation requirements specified in Clause 7.8.3.

7.8.15.2 Subgrade for cast-in-place structures 7.8.15.2.1 Undisturbed foundation Firm to hard in-situ foundation soils shall be undisturbed. Soils on top of the foundation shall be compacted to the same stiffness as the undisturbed in-situ soil to maintain uniform support along the length of the conduit. Foundation soils that could be disturbed by the construction process shall be protected.

7.8.15.2.2 Control of line and grade Line and grade shall be maintained to allow construction of structures at the specified location and with the specified minimum wall thickness. Low spots shall be filled with concrete or with soil compacted to the same stiffness as the undisturbed in-situ soil.

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7.8.15.3 Bedding for precast concrete structures 7.8.15.3.1 Uniform support and control of grade The bedding shall be constructed as required for the specific installation by Clause 7.8.3 in order to distribute the load-bearing reaction uniformly on the pipe barrel or structure base and to maintain the required conduit grade.

7.8.15.3.2 Compaction The bedding layers shall be compacted as specified for the installation design in Clause 7.8.3. For pipes designed as Type C1, C2, or C3 in accordance with Clause 7.8.3.5, or as Type B1 in accordance with Clause 7.8.3.6, the bedding layer shall be placed as uniformly as possible but shall be loosely placed and uncompacted under the middle third of the conduit wall. For all structures, the outer bedding or any bedding that may be under the lower side areas shall be compacted to at least the same requirements as apply to the outer bedding or lower side areas, whichever are more stringent.

7.8.15.3.3 Maximum aggregate size The maximum aggregate size for bedding shall not exceed 25 mm unless the bedding has a thickness of 150 mm or greater, in which case the maximum aggregate size shall not exceed 38 mm.

7.8.15.3.4 Bell holes Bell holes shall be excavated in the bedding or foundation when pipe with expanded bells is installed so that the pipe is supported by the barrel and not by the bells.

7.8.15.4 Placement and joining of precast structures 7.8.15.4.1 Control of line and grade Structures shall be installed to the line and grade shown on the Plans. Joining shall be in accordance with the manufacturer’s recommendations. Before the precast section is joined, it shall be brought to correct alignment and the top positioned.

7.8.15.4.2 Adjustments in alignment If the precast section being installed is misaligned, the section shall be completely disconnected, the alignment corrected, and the section rejoined. Alignments shall not be adjusted by exerting force on the barrel of the section or by lifting and dropping the section.

7.8.15.5 Structural backfill 7.8.15.5.1 Type and compaction Soils placed below and adjacent to a precast structure shall be of the type and compaction level specified in Clause 7.8.3.5 or 7.8.3.6, as applicable, for the particular location of the soils in the backfill zones. The soils shall be placed and compacted uniformly so as to distribute the load-bearing reaction uniformly to the bedding over the full length of the structure. Within 0.3 m of the conduit wall, the aggregate size shall be less than or equal to 38 mm.

7.8.15.5.2 Concrete pipe in standard installations For precast concrete pipes designed as standard installations in accordance with Clause 7.8.3.5, the haunch and lower sidefill zones shall be constructed using the soil type and minimum compaction level corresponding to the particular standard installation type.

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7.8.15.5.3 Box sections in standard installations For box sections designed as standard installations in accordance with Clause 7.8.3.6, the sidefill zones shall be constructed using the soil type and minimum compaction level corresponding to the particular standard installation type.

7.8.15.5.4 Testing When the design requires compliance with the soil type and compaction requirements of this Section, such compliance shall be verified by appropriate observations and tests performed by an Approved geotechnical Engineer.

7.8.15.6 Sidefill soils 7.8.15.6.1 Constructed soils Soils in the sidefill zones identified in Figures 7.8 to 7.11 shall be of a type and have the minimum compaction specified in Clause 7.8.3.5 or 7.8.3.6, as applicable, or the minimum compaction of the overfill soils, whichever is greater. Constructed soils shall not contain debris, organic matter, frozen materials, or large stones of a diameter greater than one-half the thickness of the compacted layers being placed or 100 mm, whichever is smaller. Soils shall be deposited uniformly on each side of the structure in order to prevent lateral displacement.

7.8.15.6.2 In-situ soils In-situ soils that are located in the sidefill zones of trenches whose walls have a slope greater than 10° from the vertical and are less stiff than the constructed overfill soils shall be removed and replaced with compacted soils whose stiffness is at least that of the overfill soils.

7.8.15.7 Overfill soils 7.8.15.7.1 Type, compaction, and unit weight Overfill soils shall be constructed as specified in this Section. The compaction shall not be greater than the compaction or equivalent stiffness of soils in the sidefill zone and foundation. The average unit weight shall not exceed the design unit weight of overfill soil.

7.8.15.7.2 Structures below pavements Overfill in trenches and in other locations where pavements require control of differential settlement shall be of a type and compaction level that can control pavement differential settlement within acceptable limits for the particular type of pavement.

7.8.15.8 Trenches 7.8.15.8.1 General The walls of trenches shall be maintained in a stable condition so as to permit safe construction operations and compliance with applicable safety standards.

7.8.15.8.2 Width control When required by the installation design, trench width shall be controlled within the limits shown on the Plans. If no width limits are shown, the trench width shall be sufficient to facilitate compliance with this Section’s requirements for compaction of soils in the haunch zone.

7.8.15.8.3 Sheathing removal Unless sheathing is to be left in place, it shall be pulled out in vertical increments in order to permit placement and compaction of fill material for the full width of the trench.

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7.8.15.8.4 Trench shields and boxes When trench shields or boxes are moved, the previously installed structure shall not be disturbed and any void left by the trench box shall be filled with soil, compacted as specified in this Section.

7.8.15.9 Protection from construction equipment overload 7.8.15.9.1 Limitation of construction loads The load imposed on an installed structure by construction equipment shall be limited to a load that does not exceed the design strength of the buried structure. For box sections and similar structures, the effects of approaching wheel loads adjacent to the sides of the structure, as well as the effects of loads above the structure, shall be considered.

7.8.15.9.2 Extent of overfill for support of construction loads In an embankment installation, the full overfill depth required to support construction equipment loads shall extend at least one structure width or 3.0 m, whichever is greater, beyond each side of the installed structure so as to protect the structure from excessive loading and to prevent possible lateral displacement of the structure. The overfill may be ramped beyond this width in order to facilitate passage of the construction equipment over an installed structure. If a large volume of construction traffic needs to cross an installed structure, the point of crossing shall be changed from time to time, in accordance with engineering judgment, to minimize the possibility of lateral displacement.

7.8.15.10 Site supervision and construction control The Plans shall require that the Engineer designated by the Owner as responsible for inspection of the construction shall be experienced in the design and construction of soil installations for buried concrete structures. Construction shall be inspected for compliance with the compaction and testing requirements of Clauses 7.8.15.3 and 7.8.15.5 to 7.8.15.7. Records (including recorded observations) covering at least the following construction processes shall be provided: (a) the condition of the foundation before installation of bedding (to include observations of in-situ soils below and adjacent to the structure); (b) the type and compaction of bedding soil (including avoidance of bedding compaction near pipe inverts when such control is specified by the installation design); (c) the type and compaction of embedment soils, especially below the pipe haunches and immediately adjacent to the conduit structures; (d) for embankment installations, the type and compaction of embankment in the region adjacent to the height of the conduit; (e) for trench installations, the width of the trench at the top and bottom of the conduit, the slope of the trench wall, and the type and stiffness of in-situ material in the trench and wall; (f) the type and compaction of overfill soils above the conduit; and (g) the type and compaction of the pavement sub-base, if any, and the type of pavement.

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Section 8 — Concrete structures 8.1 8.2 8.3 8.4 8.4.1 8.4.2 8.4.3 8.4.4 8.4.5 8.4.6 8.5 8.5.1 8.5.2 8.5.3 8.5.4 8.6 8.6.1 8.6.2 8.6.3 8.7 8.7.1 8.7.2 8.7.3 8.7.4 8.8 8.8.1 8.8.2 8.8.3 8.8.4 8.8.5 8.8.6 8.8.7 8.9 8.9.1 8.9.2 8.9.3 8.9.4 8.9.5 8.10 8.10.1 8.10.2 8.10.3 8.10.4 8.10.5 8.10.6 8.11 8.11.1 8.11.2 8.11.3 8.12 8.12.1

Scope 304 Definitions 304 Symbols 307 Materials 313 Concrete 313 Reinforcing bars and deformed wire 316 Tendons 316 Anchorages, mechanical connections, and ducts 317 Grout 318 Material resistance factors 318 Limit states 319 General 319 Serviceability limit states 319 Fatigue limit state 319 Ultimate limit states 320 Design considerations 320 General 320 Design 320 Buckling 323 Prestressing 323 Stress limitations for tendons 323 Concrete strength at transfer 324 Grouting 324 Loss of prestress 324 Flexure and axial loads 326 General 326 Assumptions for the serviceability and fatigue limit states 326 Assumptions for the ultimate limit states 327 Flexural components 327 Compression components 328 Tension components 331 Bearing 331 Shear and torsion 331 General 331 Design procedures 332 Sectional design model 333 Slabs, walls, and footings 337 Interface shear transfer 337 Strut-and-tie model 338 General 338 Structural idealization 338 Proportioning of a compressive strut 339 Proportioning of a tension tie 340 Proportioning of node regions 340 Crack control reinforcement 340 Durability 341 Deterioration mechanisms 341 Protective measures 341 Detailing for durability 346 Control of cracking 347 General 347

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8.12.2 8.12.3 8.12.4 8.12.5 8.12.6 8.13 8.13.1 8.13.2 8.13.3 8.14 8.14.1 8.14.2 8.14.3 8.14.4 8.14.5 8.14.6 8.15 8.15.1 8.15.2 8.15.3 8.15.4 8.15.5 8.15.6 8.15.7 8.15.8 8.15.9 8.16 8.16.1 8.16.2 8.16.3 8.16.4 8.16.5 8.16.6 8.16.7 8.17 8.18 8.18.1 8.18.2 8.18.3 8.18.4 8.18.5 8.18.6 8.18.7 8.19 8.19.1 8.19.2 8.19.3 8.19.4 8.20 8.20.1 8.20.2 8.20.3 8.20.4 8.20.5

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Distribution of reinforcement 347 Reinforcement 347 Crack control in the side faces of beams 348 Flanges of T-beams 348 Shrinkage and temperature reinforcement 348 Deformation 348 General 348 Dimensional changes 349 Deflections and rotations 349 Details of reinforcement and special detailing requirements 350 Hooks and bends 350 Spacing of reinforcement 351 Transverse reinforcement for flexural components 352 Transverse reinforcement for compression components 352 Reinforcement for shear and torsion 353 Maximum spacing of reinforcement for shear and torsion 353 Development and splices 353 Development 353 Development of reinforcing bars and deformed wire in tension 355 Development of reinforcing bars in compression 356 Development of pretensioning strand 357 Development of standard hooks in tension 357 Combination development length 358 Development of welded wire fabric in tension 358 Mechanical anchorages 358 Splicing of reinforcement 358 Anchorage zone reinforcement 360 General 360 Post-tensioning anchorage zones 360 Pretensioning anchorage zones 363 Inclined anchorages 363 Intermediate anchorages 363 Anchorage blisters 363 Anchorage of attachments 363 Seismic design and detailing 366 Special provisions for deck slabs 367 Design methods 367 Minimum slab thickness 367 Allowance for wear 367 Empirical design method 367 Diaphragms 370 Edge stiffening 370 Distribution reinforcement 370 Composite construction 372 General 372 Flexure 372 Shear 372 Semi-continuous structures 372 Concrete girders 373 General 373 Effective flange width for T- and box girders 373 Flange thickness for T- and box girders 373 Isolated girders 373 Top and bottom flange reinforcement for cast-in-place T- and box girders 373

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8.20.6 8.20.7 8.21 8.22 8.22.1 8.22.2 8.22.3 8.22.4 8.22.5 8.22.6 8.22.7 8.23 8.23.1 8.23.2 8.23.3 8.23.4 8.23.5 8.23.6 8.23.7

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Post-tensioning tendons 374 Diaphragms 374 Multi-beam decks 374 Segmental construction 374 General 374 Additional ducts and anchorages 374 Diaphragms 375 Deviators for external tendons 375 Coupling of post-tensioning tendons 375 Special provisions for various bridge types 375 Precast segmental beam bridges 377 Concrete piles 378 General 378 Specified concrete strength 378 Handling 378 Splices 378 Pile dimensions 378 Non-prestressed concrete piles 378 Prestressed concrete piles 379

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Section 8 Concrete structures 8.1 Scope This Section specifies requirements for the design of structural components that are made of precast or cast-in-place normal-density, low-density, or semi-low-density concrete and reinforced with prestressed or non-prestressed steel. The components covered by this Section can be prestressed with pretensioned steel, grouted post-tensioned steel, or both.

8.2 Definitions The following definitions apply in this Section: Adhesive anchor — an anchor inserted into a hole drilled in hardened concrete and held in place by epoxy resin or another adhesive. Anchor — a bolt, stud, or reinforcing bar embedded in concrete. Anchorage — (a) in post-tensioning, a device used to anchor a tendon to a concrete member; (b) in pretensioning, a device used to anchor a tendon until the concrete has reached a predetermined strength; and (c) for reinforcing bars, a length of reinforcement, mechanical anchor, or hook, or a length of reinforcement combined with a mechanical anchor or a hook. Anchorage blister — a protrusion in a web, flange, or flange-web junction for placement of tendon anchorage fittings. Anchorage system — an anchor or assemblage of anchors. At jacking — at the time of tensioning tendons. Attachment — a structure external to concrete that transmits loads to an anchor. At transfer — at the time immediately after transfer. Bonded tendon — a tendon that is bonded to concrete directly or by grouting. Cast-in-place anchor — an anchor that is in its final location at the time of placing of concrete. Closure — a cast-in-place concrete segment used to complete a span in segmental construction. Concrete cover — the least distance between the surface of reinforcing bars, strands, post-tensioning ducts, anchorages, or connections and the surface of concrete. Creep — time-dependent deformation of concrete under sustained load. Curvature friction — the friction resulting from the curvature of the specified profile of post-tensioning tendons. Decompression — a condition at which the concrete compressive stress induced by prestress, at a specified point in a section, is reduced to zero by the tensile stress due to applied loads.

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Deep beam — a member with a span-to-depth ratio of less than 2.0, where for continuous spans a effective span is taken as the distance between points of contraflexure due to dead load. Development length — the length of embedded reinforcement required to develop the specified strength of the reinforcement. Deviator — a protrusion in a web, flange, or web-flange junction cast at appropriate locations in a span to control the geometry or to provide a means for changing the direction of external tendons. Duct — an opening in concrete for internal post-tensioning tendons. Edge distance — the minimum distance between the anchor centreline and the free edge of the concrete. Effective depth — the distance from the extreme compression fibre to the centroid of the tensile force. Effective prestress — the stress or force remaining in the tendons or the concrete after all losses have occurred. Embedment depth — the distance from the bearing surface of the anchor in tension to the surface of the concrete. Embedment length — the length of embedded reinforcement provided beyond a critical section. Equivalent embedment length — the length of embedded straight reinforcement that can develop the same strength as that which can be developed by a standard hook or mechanical anchorage. External tendon — a post-tensioning tendon placed outside a web or flange (usually inside a box girder cell). Grouted anchor — an anchor grouted into a hole drilled in hardened concrete. Internal tendon — a post-tensioning tendon embedded in a member. Jacking force — the force applied to stress tendons. For pretensioning, the specified jacking force excludes the force to compensate for anchorage slip and temperature correction. For post-tensioning, the specified jacking force includes an allowance to compensate for anchorage slip. Low-density concrete — concrete with an air-dry density not greater than 1850 kg/m3 (determined in accordance with ASTM C 567). Multi-beam decks — deck systems consisting of precast components placed side-by-side. Normal-density concrete — concrete having a fresh density between 2150 and 2500 kg/m3 (determined in accordance with CAN/CSA-A23.2). Post-tensioning — a method of prestressing in which the tendons are stressed after the concrete has reached a predetermined strength. Precast components — concrete components that are cast in a location other than their final position and manufactured and erected in accordance with CAN/CSA-A23.4. Prestressed concrete — reinforced concrete with an average effective prestress of at least 1.50 MPa. Pretensioning — a method of prestressing in which the tendons are stressed before the concrete is placed. Reinforcement — steel in the form of reinforcing bars, wires, wire fabric, or tendons. Relaxation — the time-dependent reduction of stress in tendons at constant strain. November 2006

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Secondary prestressing effects — the effects caused by restraint of deformation resulting from the prestressing force. Segmental girder — a girder made up of individual components post-tensioned together to act as a monolithic unit under loads. Semi-low-density concrete — concrete with an air-dry density greater than 1850 kg/m3 but less than 2150 kg/m3 (determined in accordance with ASTM C 567). Shear lug — a plate or bar that transmits shear forces to concrete. Sheath — a tube-like component for forming a duct for internal post-tensioning and for containing tendons and grout for external post-tensioning. Skew angle — the angle formed by subtracting the acute angle of the parallelogram from 90° in a slab panel in the form of a parallelogram. Slab — a component with a width at least four times the effective depth. Spacing — the distance between centrelines of adjacent reinforcing bars, wires, tendons, or anchors. Specified strength of concrete — the 28-day compressive strength of concrete as specified on the Plans and determined in accordance with CAN/CSA-A23.2. Specified strength of tendon — the tensile strength or breaking load of a tendon per unit area as specified on the Plans and determined in accordance with CSA G279. Spiral — continuously wound bar or wire in the form of a cylindrical helix. Stress range — the algebraic difference, at the fatigue limit state, between the maximum and minimum stresses for reinforcing bars or the increase in tension for tendons. Tendon — a high-strength steel element used to impart prestress to concrete. Tension stiffening — the stiffening effect on a member due to the contribution of the uncracked concrete between cracks. Transfer — the act of transferring force in tendons to concrete. Transfer length — the length over which a prestressing force is transferred to concrete by bond in a pretensioned component. Transverse reinforcement — reinforcement used to resist shear, torsion, or lateral forces in a structural component (typically deformed bars bent into U, L, or rectangular shapes and located not parallel to longitudinal reinforcement). Note: The term “stirrups” is usually applied to transverse reinforcement in flexural components and the term “ties” to transverse reinforcement in compression components.

Wall-type compression component — a component with a rectangular cross-section having a width-to-depth ratio of 4 or greater. Wobble friction — the friction caused by the unintended deviation of a post-tensioning sheath or duct from its specified profile. Yield strength — the specified minimum yield strength of reinforcement.

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8.3 Symbols The following symbols apply in this Section: Ab

= area of an individual reinforcing bar, mm2; bearing area of a post-tensioned anchor, mm2

Abr

= bearing area of an anchor or shear lug, mm2

Ac

= area of core of a spirally reinforced compression member measured out-to-out of spirals, mm2

Acp

= area enclosed by the outside perimeter of a concrete cross-section, including the area of holes, if any, mm2

Acs

= effective cross-sectional area of a compressive strut, mm2

Act

= area of concrete on the flexural tension side of a member, mm2

Acv

= area of concrete resisting shear transfer, mm2

Ag

= gross cross-sectional area, mm2

Ao

= area enclosed by shear flow path, including the area of holes, if any, mm2

Aoh

= area enclosed by the centreline of exterior closed transverse torsion reinforcement, including the area of voids, if any, mm2

Aps

= area of tendons on the flexural tension side of a member, mm2

As

= area of reinforcing bars on the flexural tension side of a member, mm2

As’

= area of reinforcing bars on the flexural compression side of a member, mm2

Ass

= area of reinforcement in the strut, mm2

Ast

= area of reinforcement in the tie, mm2; total area of longitudinal reinforcing bars, mm2

At

= area of closed transverse torsion reinforcement, mm2

Atr

= area of reinforcement within ld that crosses the potential bond-splitting crack, mm2

Av

= area of transverse shear reinforcement perpendicular to the axis of a member within a distance s, mm2

Avf

= area of shear-friction reinforcement, mm2

Aw

= area of an individual wire to be developed or spliced, mm2

A1

= loaded area, mm2

A2

= maximum area of the portion of the supporting surface that is geometrically similar to and concentric with the loaded area and does not overlap similar areas from adjacent loaded areas, mm2

ANC

= loss of prestress due to slip of post-tensioning tendon at anchorage, MPa

a

= depth of an equivalent rectangular stress block, mm (see Clause 8.8.3); lateral dimension of the anchorage device measured parallel to the larger dimension of the cross-section, mm; maximum size of aggregate, mm; difference between mean concrete strength and specified strength fc‘ at 28 days

ag

= specified nominal size of coarse aggregate, mm

Br

= factored bearing resistance of a concrete component, N

b

= width of the compression face of member, mm; lateral dimension of the anchorage device measured parallel to the smaller dimension of the cross-section, mm

bo

= perimeter of the critical section for slabs and footings, mm

bv

= effective web width within depth dv , mm (see Clause 8.9.1.6)

bw

= web width, mm

Cm

= factor relating the actual moment diagram to an equivalent uniform moment diagram

CR

= loss of prestress due to creep of concrete, MPa

c

= distance from extreme compression fibre to neutral axis, mm; cohesion for interface shear transfer, MPa; distance from centroidal axis of a pile to the extreme fibre in tension or compression, mm

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cd

= cover to a post-tensioning duct, mm

d

= effective depth (being the distance from the extreme compression fibre to the centroid of the tensile force), mm

da

= nominal diameter of an anchor, mm

db

= nominal diameter of a bar, wire, or prestressing strand, mm

dba

= nominal diameter of a reinforcing bar anchoring a strut, mm

dbs

= distance from the loaded surface to the centroid of the bursting force, mm

dcs

= the smaller of (a) the distance from the closest concrete surface to the centre of the bar being developed; and (b) two-thirds the centre-to-centre spacing of the bars being developed, mm

dd

= nominal diameter of a post-tensioning duct, mm

deff

= effective length of a shear plane at post-tensioning ducts, mm

dp

= distance from the extreme compression fibre to the centroid of the tendons, mm

dv

= effective shear depth, mm

Ec

= modulus of elasticity of concrete, MPa

Ec,28

= modulus of elasticity of concrete at 28 days, MPa

Ec(t0)

= modulus of elasticity of concrete at time of loading, MPa

Eci

= modulus of elasticity of concrete at transfer, MPa

Ep

= modulus of elasticity of tendons, MPa

Es

= modulus of elasticity of reinforcing bars, MPa

EI

= flexural stiffness, N•mm2

ES

= loss of prestress due to elastic shortening of concrete, MPa

e

= base of Napierian logarithms; eccentricity, mm

Ff

= factored tensile force on an anchor, N

F’

= reduced force effect due to creep

Fl

= lateral force per unit length due to the multi-strand effect in a curved tendon, N/mm

Flc

= required tensile force in longitudinal reinforcement on the flexural compression side of a member, N

Flt

= required tensile force in longitudinal reinforcement on the flexural tension side of a member, N

Fpu

= total specified strength of tendons, N

Fr

= factored tensile resistance of an anchor, N; distributed thrust per unit length in the plane of the curved tendon, N/mm

Fs

= force in tendons, N

FR

= loss of prestress due to friction at a point x metres from the jacking end, MPa

fc‘

= specified compressive strength of concrete, MPa

fc′

= square root of the specified compressive strength of concrete, which after being multiplied by an empirical constant with suitable units is expressed in megapascals

fca

= compressive stress in concrete immediately behind an anchorage device, MPa

fcds

= concrete stress at the centre of gravity of tendons due to all dead loads except the dead load present at transfer at the same section or sections for which fcir is calculated (the stress being positive when tensile), MPa

fce

= axial concrete stress that can be taken as fpc for prestressed members and Nf /Ag for non-prestressed members (the stress being positive when compressive), MPa

fci’

= compressive strength of concrete at transfer, MPa

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fci′

Canadian Highway Bridge Design Code

= square root of the compressive strength of concrete at transfer, which after being multiplied by an empirical constant with suitable units is expressed in megapascals

fcir

= concrete stress at the centre of gravity of tendons due to the prestressing effect at transfer and the self-weight of the member at sections of maximum moment, MPa

fcr

= cracking strength of concrete, MPa

fcri

= cracking strength of concrete at transfer, MPa

fcu

= limiting compressive stress in a strut, MPa; crushing strength of concrete, MPa

fl

= calculated stress in concrete due to specified live load, MPa

fpc

= compressive stress in concrete after all prestress losses have occurred, either at the centroid of the cross-section resisting live load or at the junction of the web and flange when the centroidal axis lies in the flange, MPa; for two-way action, the average of the values of compressive stress in concrete for the two directions, after all prestress losses, at the centroid of the section, MPa

fpo

= stress in prestressed reinforcement when stress in the surrounding concrete is zero, MPa

fps

= stress in tendons at the ultimate limit state, MPa

fpu

= specified tensile strength of prestressing steel, MPa

fpy

= yield strength of prestressing steel (may be taken as 0.90fpu for low-relaxation strands, 0.85fpu for smooth high-strength bars, and 0.80fpu for deformed high-strength bars), MPa

fs

= tensile stress in reinforcing bars, MPa

fse

= effective stress in prestressing steel after losses, MPa

fsi

= stress in pretensioning strand just prior to transfer, MPa

fsj

= stress in prestressing steel at jacking, MPa

fst

= stress in prestressing steel at transfer, MPa

fsu

= specified tensile strength of anchor steel, MPa

ftl

= tensile stress in concrete at the serviceability limit state, MPa

fw

= stress in reinforcement under conditions causing cracking, calculated on a cracked section

fy

= specified yield strength of reinforcing bars, MPa

h

= overall thickness of a component, mm; the lateral dimension of the cross-section in the direction considered, mm; overall thickness of a deck slab, including the precast panel if present, mm

ha

= height of a strut at the outside edge of bearing, as shown in Figure 8.4(b), mm

ho

= a notional thickness that is a function of λ and rv , mm

hs

= height of strut, as shown in Figure 8.4(c), mm

Icr

= moment of inertia of a cracked section, transformed to concrete, mm4

Ie

= effective moment of inertia, mm4

Ig

= moment of inertia of the gross concrete section about the centroidal axis, neglecting the reinforcement, mm4

Is

= moment of inertia of the reinforcement about the centroidal axis of component cross-section, mm4

K

= wobble friction coefficient per metre length of a prestressing tendon

Kcr

= factor used to calculate prestress loss due to creep of concrete

Ktr

= transverse reinforcement index (see Clause 8.15.2.2)

k

= effective length factor for compression members

kb

= parameter used in calculating crack width (to account for the type of force causing the cracking) (see Clause 8.12.3.2)

kp

= factor dependent on the type of prestressing steel specified in Clause 8.8.4.2

k1

= bar location factor

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k2

= coating factor

k3

= bar size factor

l

= length, mm

la

= length of a reinforcing bar anchoring a strut, as shown in Figure 8.4(a), mm

lb

= length of bearing, mm

ld

= development length, mm

ldh

= development length of a standard hook in tension measured from the critical section to the outside end of the hook, mm

le

= effective length, mm

lhb

= basic development length of a standard hook in tension measured from the critical section to the outside end of the hook, mm

lu

= unsupported length of a compression member, mm

Ma

= maximum moment in a member at the stage for which the deformation is being calculated, N•mm; allowable flexural moment on a pile without axial load at the serviceability limit state, N•mm

Mc

= magnified moment used for proportioning slender compression members, N•mm

Mcr

= cracking moment, N•mm

Mf

= factored moment at a section, N•mm

Mr

= factored flexural resistance of a section in bending, N•mm

Mrx

= factored flexural resistance of a section about the x-axis, N•mm

Mry

= factored flexural resistance of a section about the y-axis, N•mm

Ms

= flexural moment at a section under consideration at the serviceability limit state load, N•mm

Mx

= component about the x-axis of the moment due to factored loads, N•mm

My

= component about the y-axis of the moment due to factored loads, N•mm

M1

= value of the smaller end moment at the ultimate limit state due to factored loads acting on a compression member (to be taken as positive if the member is bent in single curvature and negative if it is bent in double curvature), N•mm

M2

= value of the larger end moment at the ultimate limit state due to factored loads acting on a compression member (always taken as positive), N•mm

N

= total number of post-tensioning tendons; unfactored permanent load normal to the interface area (taken as positive for compression and negative for tension), N

Nf

= factored axial load normal to the cross-section occurring simultaneously with Vf , including the effects of tension due to creep and shrinkage, N

n

= modular ratio (= Es / Ec or Ep / Ec ); number of anchorages in a row; projection of a base plate beyond the wedge hole or wedge plate, as applicable, mm; number of bars or wires being developed along the potential plane of bond splitting

Pa

= allowable axial load on a prestressed concrete pile without flexure at the serviceability limit state, N

Pc

= buckling load, N

Pf

= factored axial load at a section at the ultimate limit state, N

Po

= factored axial resistance of a section in pure compression, N

Pr

= factored axial resistance of a section in compression with minimum eccentricity, N

Prx

= factored axial resistance in compression corresponding to Mrx , N

Prxy

= factored axial resistance in compression with biaxial loading, N

Pry

= factored axial resistance in compression corresponding to Mry , N

Ps

= axial load at a pile section at the serviceability limit state, N

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pc

= outside perimeter of a concrete section, mm

ph

= perimeter of closed transverse torsion reinforcement measured along its centreline, mm

R

= reduction factor for laterally unsupported piles (see Clause 8.23.7.2.2); radius of curvature of a tendon, mm

REL1

= loss of prestress due to relaxation of prestressing steel before transfer, MPa

REL2

= loss of prestress due to relaxation of prestressing steel after transfer, MPa

RH

= annual mean relative humidity, %

r

= radius of gyration of a gross cross-section, mm

rv

= volume per unit length of a concrete section divided by the corresponding surface area in contact with freely moving air, mm

S

= time-dependent factor for calculating deformations caused by sustained loads; effective span length of slab, m; spacing of the supporting beams for slabs, m

Se

= unsupported length of the edge-stiffening beams in deck slabs, m

SH

= loss of prestress due to shrinkage of concrete, MPa

s

= spacing of reinforcing bars, mm; spacing of stirrups measured parallel to the longitudinal axis of a component, mm; centre-to-centre spacing of multiple anchorages, mm; vertical spacing of ties, mm; maximum centre-to-centre spacing of transverse reinforcement within ld , mm

sd

= clear spacing between ducts in the plane perpendicular to the tendon deviation, mm

srm

= average spacing of cracks

sw

= spacing of wires to be developed or spliced, mm

sz

= crack spacing parameter dependent on crack control characteristics of longitudinal reinforcement, mm

sze

= equivalent value of sz that accounts for influence of aggregate size, mm

Tbs

= bursting force behind a post-tensioning anchor, N

Tcr

= torsional cracking resistance, N•mm

Tf

= factored torsional moment at a section, N•mm

Tr

= factored torsional resistance provided by shear flow, N•mm

t

= age of concrete after casting, days; time, days; thickness of a section, mm; average thickness of a bearing plate, mm

ta

= thickness of an anchor head, mm

td

= maximum projection of an anchor head, mm

t0

= age of concrete at the time of loading or from when the influence of shrinkage is calculated, days

Vc

= factored shear resistance provided by tensile stresses in concrete, N

Vcd

= resistance of concrete in the plane of the tendon curvature, N

Vf

= factored shear force at a section, N

Vp

= component in the direction of the applied shear of all of the effective prestressing forces crossing the critical section factored by φp (taken as positive if resisting the applied shear), N

Vr

= factored shear resistance, N

Vs

= factored shear resistance provided by shear reinforcement, N

v

= nominal shear stress, MPa; shear resistance of shear friction plane, MPa

w

= crack width, mm

x

= distance from the jacking end in post-tensioning, m; bonded length of pretensioned strand up to the inside edge of the bearing area, mm; length of reinforcing bar extending beyond the inner edge of the node region, mm

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α

= vector sum of angular changes in elevation and plan of a prestressing tendon profile from the jacking end to any point x, radians; angle of inclination of transverse reinforcement to the longitudinal axis of a member, degrees; angle of inclination of a tendon force with respect to the centreline of a member (positive if the anchor force points toward the centroid of the section and negative if the anchor force points away from the centroid of the section), degrees

α1 β

= ratio of average stress in a rectangular compression block to the specified concrete strength

β RH βc βd

= coefficient describing the effect of relative humidity on shrinkage in concrete

βf βs βt β1 γc Δ fs Δ fs1 Δ fs2 δ εc ε cs ε cs0 ε cσ εe

= coefficient used in calculation of creep coefficient

εs ε sm εx ε1 θ

= tensile strain in a tie; tensile strain in reinforcing bars; concrete shrinkage strain

θs κ λ1

= smallest angle between a compressive strut and the adjoining tensile tie, degrees

µ

= friction coefficient

ρ ρ’ ρc ρs

= factor used to account for the shear resistance of cracked concrete (see Clauses 8.9.3.4 and 8.9.3.6 to 8.9.3.8) = parameter used in calculating crack width = ratio of the maximum factored axial dead load to the total factored load used in Clause 8.8.5.3(f) = coefficient describing the development with time of shrinkage in concrete = coefficient used in calculation of creep coefficient = factor in Clause 8.8.3(f) = mass density of concrete, kg/m3 = total loss of prestress, MPa = loss of prestress at transfer, MPa = loss of prestress after transfer, MPa = moment magnification factor for compression members = concrete creep strain = time-varying strain in concrete due to shrinkage = notional shrinkage coefficient = total time-varying strain in concrete due to constant stress = concrete elastic strain calculated using the modulus of elasticity based on the concrete strength at 28 days = average strain in reinforcement = longitudinal strain (see Clause 8.9.3.8) = principal tensile strain, taken as a positive quantity, in cracked concrete due to factored loads = angle of inclination of the principal diagonal compressive stresses to the longitudinal axis of a member, degrees; angle of skew of a bridge, degrees = correction factor for closely spaced anchorages (see Clause 8.16.2.2.6) = parameter dependent on the density of concrete and used to determine the friction coefficient, µ = the ratio As / bd = the ratio As‘ / bd = ratio of reinforcement in the effective tension area of concrete = ratio of the volume of spiral reinforcement to the total volume of the core, out-to-out of spirals, of spirally reinforced compression members

ρv

= the ratio Avf / Acv ; ratio of the area of vertical shear reinforcement to the gross concrete area of a horizontal section

σ

= compressive stress across a shear-friction plane, MPa

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σc φ φ RH φc φp φs ψ

Canadian Highway Bridge Design Code

= stress in concrete = creep coefficient = coefficient used in calculation of creep coefficient = resistance factor for concrete (see Clause 8.4.6) = resistance factor for tendons (see Clause 8.4.6) = resistance factor for reinforcing bars (see Clause 8.4.6) = ratio of creep strain ε c to elastic strain ε e

8.4 Materials 8.4.1 Concrete 8.4.1.1 Compliance with CAN/CSA-A23.1/CAN/CSA-A23.2 Materials, methods of material testing, and construction practices shall, unless otherwise specified in this Section, comply with CAN/CSA-A23.1/CAN/CSA-A23.2.

8.4.1.2 Concrete strength Unless otherwise Approved, the specified strength of concrete, fc’, shall be a minimum of 30 MPa for non-prestressed members and a minimum of 35 MPa for prestressed members. However, concrete with strengths greater than 85 MPa shall be used only if Approved. The concrete strength shall be shown on the Plans.

8.4.1.3 Thermal coefficient In the absence of more accurate data, the thermal coefficient of linear expansion of concrete shall be taken as 10 × 10–6/ °C.

8.4.1.4 Poisson’s ratio Unless determined by Approved physical tests, Poisson’s ratio for elastic strains shall be taken as 0.2.

8.4.1.5 Shrinkage 8.4.1.5.1 General The design values of shrinkage strains in normal-density concrete shall be determined as follows: (a) in accordance with Clause 8.4.1.5.2; or (b) based on data obtained from physical tests on the same mix of concrete that is to be used in construction. The choice of method shall take into consideration the sensitivity of structural behaviour to shrinkage strain as well as the possible consequences of calculated shrinkage strains being significantly different from actual strains. The design values of shrinkage strains in low-density and semi-low-density concrete shall be determined on the basis of data obtained from physical tests on the same mix of concrete that is to be used in construction.

8.4.1.5.2 Calculation of shrinkage strain

Except as permitted in Clause 8.4.1.5.1(b), the strain, εcs , due to shrinkage that develops in an interval of time, t – t0 , shall be calculated as follows:

e cs (t − t0 ) = e cs 0 b s (t − t0 )

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where ε cs0 = notional shrinkage coefficient = b ⎡160 + 50 ⎡9 − fc′ + a ⎤ ⎤ × 10−6 RH ⎢ ⎢ 10 ⎥⎦ ⎥⎦ ⎣ ⎣ where

⎡ ⎡ RH ⎤3 ⎤ bRH = −1.55 ⎢1− ⎢ ⎥ ⎥ ⎢⎣ ⎣ 100 ⎦ ⎥⎦ a

=

difference between mean concrete strength and specified strength, fc’, at 28 days (in the absence of data from the concrete that is to be used, a may be taken as 10 MPa)

where RH =

annual mean relative humidity, %, as shown in Figure A3.1.3

β s (t – t0), which describes the development of shrinkage with time, shall be calculated as follows: b s (t − t 0 ) =

t − t0 2

⎡ 2r ⎤ 350 ⎢ v ⎥ + (t − t0 ) ⎣ 100 ⎦

8.4.1.6 Creep 8.4.1.6.1 General The design values of creep strains in normal-density concrete shall be determined as follows: (a) in accordance with Clause 8.4.1.6.2; or (b) based on data obtained from physical tests on the same mix of concrete that is to be used in construction. The choice of method shall take into consideration the sensitivity of structural behaviour to creep strain as well as the possible consequences of calculated creep strains being significantly different from actual strains. The design values of creep strains in low-density and semi-low-density concrete shall be determined on the basis of data obtained from physical tests on the same mix of concrete that is to be used in construction.

8.4.1.6.2 Calculation of time-varying strain due to stress Except as permitted in Clause 8.4.1.6.1(b), for structural components with serviceability limit state compressive stresses less than 0.4fc‘, the total time-varying strain, ε cσ (t,t0), due to a constant stress, σc (t0), applied at time t0 shall be calculated as follows:

⎡ 1 f (t , t 0 ) ⎤ e c s (t , t 0 ) = s c (t 0 ) ⎢ + ⎥ Ec ,28 ⎥⎦ ⎢⎣ Ec (t0 ) where Ec (t0) = modulus of elasticity of concrete at time of loading

φ (t,t0) = creep coefficient as specified in Clause 8.4.1.6.3 Ec,28

= modulus of elasticity of concrete at 28 days

The principle of superposition may be used to calculate strains due to a time-varying stress.

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8.4.1.6.3 Creep coefficient

The creep coefficient, φ (t,t0), shall be calculated as follows:

f (t ,t0 ) = fRH bf bt bc (t − t0 ) where

φ RH

= 1+

1− (RH ) / (100% ) 0.46 ⎡⎣( 2rv ) / 100 ⎤⎦

1/ 3

where RH = annual mean relative humidity, %, as shown in Figure A3.1.3

βf

=

βt

=

5.3 0.5

⎡⎣(fc′ + a ) / 10 ⎤⎦ where a = difference between mean concrete strength and specified strength, fc’, at 28 days (in the absence of data from the concrete that is to be used, a may be taken as 10 MPa) 1 0.1+ (t0 )

0.2

β c (t – t0) =

⎡ t − t0 ⎤ ⎢ ⎥ ⎣ bH + t − t0 ⎦

0.3

where 18 ⎡ ⎡ RH ⎤ ⎤ 2rv 150 ⎢1+ ⎢1.2 + 250 ⎥ 100% ⎥⎦ ⎥⎦ 100 mm ⎢⎣ ⎣ but shall not be taken larger than 1500

βH =

8.4.1.7 Modulus of elasticity In the absence of more accurate data, the modulus of elasticity of concrete, Ec , shall be taken as

(3000

)

fc′ + 6900 ( g c / 2300 )

1.5

8.4.1.8 Cracking strength 8.4.1.8.1 The cracking strength, fcr , shall be taken as (a) 0.4 fc′ for normal-density concrete; (b) 0.34 fc′ for semi-low-density concrete; and (c) 0.30 fc′ for low-density concrete.

8.4.1.8.2 The cracking strength at transfer, fcri , shall be taken as (a) 0.4 fci′ for normal-density concrete; (b) 0.34 fci′ for semi-low-density concrete; and (c) 0.30 fci′ for low-density concrete. November 2006

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8.4.2 Reinforcing bars and deformed wire 8.4.2.1 Reinforcing bars 8.4.2.1.1 Specification All reinforcing bars shall meet the requirements of CAN/CSA-G30.18. Grade R bars shall meet the following additional requirements: (a) the minimum elongation at rupture in a 200 mm gauge length shall be 12% for 25M bars and smaller and 10% for 30M bars and larger; and (b) the pin diameter for the 180° bend tests shall be (i) 4db for 25M bars and smaller; (ii) 6db for 30M and 35M bars; and (iii) 8db for 45M and 55M bars.

8.4.2.1.2 Welding Where welding of the reinforcing bars is permitted, the reinforcing bars shall be Grade W.

8.4.2.1.3 Yield strength The specified yield strength, fy , of reinforcing bars shall be between 300 and 500 MPa and shall be shown on the Plans.

8.4.2.1.4 Stress-strain relationship Reinforcing bars may be assumed to exhibit a bilinear stress-strain relationship with a slope, Es , equal to 200 000 MPa prior to the yield point and a slope of zero beyond the yield point.

8.4.2.1.5 Reinforcing bar diameters The bar designation number may be taken as the nominal diameter of a reinforcing bar in millimetres.

8.4.2.2 Steel wires and welded wire fabric Steel wires shall comply with the applicable requirements of CSA G30.3 and CSA G30.14. Deformed wire that complies with CSA G30.14 shall not be smaller than MD25. Welded wire fabric shall comply with the applicable requirements of CSA G30.5 and CSA G30.15. The minimum elongation of welded wire fabric, as measured over a gauge length of at least 100 mm and including at least one cross-wire, shall be 4%.

8.4.3 Tendons 8.4.3.1 General Tendons shall take the form of high-tensile-strength, low-relaxation strand or high-strength bars and shall meet the requirements of CSA G279. For pretensioned construction, tendons shall be Size Designation 9, 13, or 15 strands. Coated strands shall not be used unless Approved.

8.4.3.2 Stress-strain relationship The stress-strain relationship used shall be representative of the tendons to be used in construction.

8.4.3.3 Modulus of elasticity The modulus of elasticity of tendons, Ep , shall be based on representative stress-strain curves, when available. In the absence of such data, the following values shall be used: (a) seven-wire high-strength strand: (i) Size 9, 13, or 15: 200 000 MPa; and (ii) Size 16: 195 000 MPa; and (b) high-strength bar: 205 000 MPa.

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8.4.4 Anchorages, mechanical connections, and ducts 8.4.4.1 Anchorages for post-tensioning tendons When tested in an unbonded condition, anchorages for post-tensioning tendons shall develop at least 95% of the specified tensile strength of the tendons without exceeding the anticipated set. After tensioning and seating, anchorages shall sustain applied loads without slippage, distortion, or other changes that result in loss of prestress. The dimensions and details of the anchorages, including any reinforcement immediately behind the anchorages, shall be based on the specified strength of the tendon and the specified strength of the concrete at transfer. Anchorages for external unbonded post-tensioning tendons shall also meet Approved dynamic tests.

8.4.4.2 Anchorages for reinforcing bars Mechanical anchorage devices shall be capable of developing the yield strength of the reinforcing bars without damage to the concrete.

8.4.4.3 Mechanical connections for post-tensioning tendons When tested in an unbonded condition, couplers for post-tensioning tendons shall develop 95% of the specified tensile strength of the tendons without exceeding the anticipated set. Couplers for external unbonded post-tensioning tendons shall also meet Approved dynamic tests. Couplers and their components shall be enclosed in housings. The housings shall be long enough to permit the necessary movements and shall be provided with fittings to allow complete grouting. Couplers shall not reduce the elongation at rupture below the requirements of the tendon itself. Couplers shall not be used at points of sharp tendon curvature or in the vicinity of points of maximum moments.

8.4.4.4 Mechanical connections for reinforcing bars Mechanical connections for reinforcing bars shall develop, in tension or compression (as required), the greater of 120% of the specified yield strength of bars or 110% of the mean yield strength of the actual bars used to test the mechanical connection. The total slip of the reinforcing bars within the splice sleeve of the connector after loading in tension to 0.5fy and relaxing to 0.05fy shall not exceed the following measured displacements between gauge points straddling the splice sleeve: (a) for bars sizes up to and including 45M: 0.25 mm; and (b) for 55M bars: 0.75 mm.

8.4.4.5 Ducts 8.4.4.5.1 General Sheaths for internal post-tensioning ducts shall be made of bright steel, galvanized steel, or plastic. The sheaths shall be corrugated and shall be non-reactive with concrete, tendons, and grout. The shape of corrugations shall be such that the sheaths can be completely filled with grout. Sheaths for external post-tensioning shall be made of plastic.

8.4.4.5.2 Size For single-strand or bar tendons, the inside diameter of the sheaths for post-tensioning ducts shall be at least 6 mm larger than the nominal diameter of the strand or bar. For multiple-strand tendons, the inside cross-sectional area of the sheath shall be at least twice the cross-sectional area of the prestressing tendon. The inside diameter of a circular sheath or an equivalent diameter of a non-circular sheath shall not exceed 40% of the least gross concrete thickness at the duct.

8.4.4.5.3 Steel sheaths Sheaths shall be watertight under an internal pressure of 350 kPa. Rigid steel sheaths shall have a wall thickness of at least 0.6 mm and shall permit bending of the sheath to a minimum inside radius of

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curvature of 9 m without distress. Semi-rigid steel sheaths shall have a wall thickness of at least 0.25 mm and shall permit the bending of the sheath to a minimum inside radius of curvature of 3.5 m without distress.

8.4.4.5.4 Plastic sheaths Unless otherwise Approved, plastic sheaths, including their splices, shall be made of high-density polyethylene conforming to ASTM D 3350 Cell Classification 324420C, shall be vapour tight, and shall remain vapour tight after tendon installation and stressing. The polyethylene sheath shall be manufactured in accordance with ASTM D 2239. Plastic sheaths shall not be used when the radius of curvature of the tendon is less than 10 m. The sheaths shall be capable of bending to the specified minimum radius of curvature without local buckling or damage. The sheath wall thickness shall be such that for the specified minimum radius of curvature the remaining wall thickness, after a tendon movement of 750 mm under a tendon stress of 80% of the specified strength, will not be less than 1 mm. For curved sheaths, the radial force exerted by a single strand on the sheath wall shall not exceed40 kN/m. The stiffness of plastic sheaths shall be such that (a) for sheaths with an inside diameter of 50 mm or less, a 3 m length supported at the ends will not deflect, under its own weight, more than75 mm at room temperature (i.e., not less than 20 °C); (b) for sheaths with an inside diameter of more than 50 mm, a 6 m length supported at the ends will not deflect, under its own weight, more than 75 mm at room temperature; and (c) the sheath shall not dent more than 3 mm under a point load of 445 N applied through a 10M reinforcing bar between the corrugation ribs at room temperature. Sheaths and their splices for external post-tensioning shall be smooth, seamless, and capable of withstanding a grouting pressure of at least 1000 kPa.

8.4.4.5.5 Vents and drains Ducts shall be provided with vents and drains at appropriate locations.

8.4.4.5.6 Ducts at deviators Within deviators, the sheaths for post-tensioning tendons shall consist of (a) galvanized steel pipe in accordance with ASTM A53/A53M, Type E, Grade B, with a wall thickness not less than 3 mm, and bent to conform to the tendon alignment; or (b) an Approved sheath detail. 

8.4.4.6 Anchor rods and studs Anchor rods and studs shall comply with Section 10.

8.4.5 Grout 8.4.5.1 Post-tensioning Unless otherwise Approved, grout for post-tensioning ducts shall comply with CAN/CSA-A23.1 and have a compressive strength of at least 35 MPa at 28 days.

8.4.5.2 Other applications Grout for other applications shall be Approved.

8.4.6 Material resistance factors The material resistance factors specified in Table 8.1 shall be used to calculate the factored resistance

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Table 8.1 Material resistance factors (See Clause 8.4.6.)



Material

Material resistance  factor

Concrete

 c = 0.75

Reinforcement Reinforcing bars, wire, and wire fabric Prestressing strands High-strength bars

 s = 0.90  p = 0.95  p = 0.90

Anchor rods and studs

In accordance with Section 10

8.5 Limit states 8.5.1 General Bridge components and retaining walls shall be proportioned to satisfy the requirements at the serviceability limit states, fatigue limit state, and the ultimate limit states.

8.5.2 Serviceability limit states 8.5.2.1 General The cracking, deformation, stress, and vibration serviceability limit states shall be considered.

8.5.2.2 Cracking The requirements of Clause 8.12 shall be met, except for tensile surfaces of components that are permanently covered with 600 mm or more of earth.

8.5.2.3 Deformation The requirements of Clause 8.13 shall be met and attention shall be given to short- and long-term deformations that could affect the function of the structure.

8.5.2.4 Stress The stresses in a component shall not exceed the values specified in Clauses 8.7.1, 8.8.4.6, and 8.23.7, as applicable.

8.5.2.5 Vibration The requirements of Section 3 with respect to vibration of the structure shall be met.

8.5.3 Fatigue limit state 8.5.3.1 Reinforcing bars Except for reinforcement in deck slabs designed in accordance with Clause 8.18.4, the following requirements shall apply: (a) The stress range in straight bars shall not exceed 125 MPa. (b) The stress range at anchorages, connections, and bends shall not exceed 65 MPa.

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(c) Unless otherwise Approved, tack welding of reinforcing bars shall not be permitted. For bars containing complete joint penetration groove welds that meet the requirements of CSA W186, the stress range in the vicinity of welds shall not exceed 100 MPa. For other types of welded splices, the stress range shall not exceed 65 MPa.

8.5.3.2 Tendons The stress range in strands in corrugated steel ducts or for pretensioning strands shall not exceed 125 MPa for radii of curvature of 10 m or more and 70 MPa for radii of curvature of 3.5 m or less. Linear interpolation shall be used for intermediate radii. The stress range in strands in corrugated plastic ducts shall not exceed 125 MPa. The stress range in deformed and smooth high-strength bars shall not exceed 70 and 90 MPa, respectively. The stress range in tendons at couplers shall not exceed 70 MPa.

8.5.4 Ultimate limit states 8.5.4.1 General The ultimate limit states to be considered shall be those of strength and stability.

8.5.4.2 Strength Structural components shall be proportioned so that the factored resistances are equal to or greater than the effects of factored loads.

8.5.4.3 Stability The structure as a whole and its components shall be proportioned to resist sliding, overturning, uplift, and buckling. The effects of the eccentricity of loads shall be considered.

8.6 Design considerations 8.6.1 General Except as permitted by Clause 8.6.2.6, load effects shall be determined by elastic analysis, while still retaining equilibrium and strain compatibility. The strut-and-tie model specified in Clause 8.10 may be used to proportion reinforcement and concrete sections in areas near supports, concentrated loads, and abrupt changes in cross-sections.

8.6.2 Design 8.6.2.1 General Components shall be proportioned for all load stages that can be critical during the life of the structure, including construction.

8.6.2.2 Member stiffness Any reasonable assumption may be adopted for computing the axial, flexural, shear, and torsional stiffnesses, provided that the assumption is used consistently throughout the analysis.

8.6.2.3 Imposed deformations Imposed deformations due to elastic shortening, shrinkage, temperature change, creep, movement of supports, and other causes shall be considered. The effects on adjoining elements of a structure due to deformations caused by prestressing shall be considered.

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The restraining forces produced in the adjoining elements may be reduced to take account of the effects of creep. The reduced restraining forces in the adjoining elements due to the prestress in a component, F‘, may be calculated as follows:

F ′ = F (1− e −Y (t ,t0 ) ) where

Ψ (t,t0) = ratio of creep strain at time t for the loading applied at time t0 In the absence of a more accurate procedure, the shrinkage stresses shall be reduced by 60% to account for creep.

8.6.2.4 Stress concentrations Stress concentrations induced by prestressing, other loads, or restraints shall be considered.

8.6.2.5 Secondary effects due to prestress Secondary effects in statically indeterminate structures induced by prestress shall be considered. The factored secondary effects shall be included with the factored load effects.

8.6.2.6 Redistribution of force effects When a statically indeterminate structure is constructed in stages, the redistribution of the permanent loads and prestressing effects due to creep shall be taken into account. Non-linear analysis may be used to determine the redistribution of load effects due to concrete cracking and material non-linearity in statically indeterminate structures. For continuous beams, in lieu of such analysis, the negative moments at the ultimate limit states obtained by linear elastic analysis may be decreased or increased by not more than 20(1 – 2.26c / d)%, provided that c/ d is less than or equal to 0.28 and the positive moments are adjusted accordingly.

8.6.2.7 Directional change of tendons 8.6.2.7.1 Thrusts in plane of tendons Thrusts produced by directional change of tendons shall be investigated and resisted by the concrete or by reinforcing bars. The design forces shall be taken as the specified strength of the tendons. The magnitude of the thrust in the plane of the tendon deviation shall be calculated as shown in Figure 8.1. The resistance per unit length provided by the concrete cover in the plane of the tendon curvature, Vcd , may be taken equal to 0.40φ c deff fcr , where deff is the lesser of 2(bw – dd /2) and 2(cd + dd /4 + ∑sd / 2) when sd is greater than or equal to dd , and is equal to 2(cd + dd /4) when sd is less than dd . Where the resistance provided by the concrete cover is less than the thrust, fully anchored tie-backs to resist the total thrust shall be provided.

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2q Fs

Fs Fs

Fs

Concentrated thrust = 2Fs sinq N

Abrupt direction change

R

Distributed thrust per unit length Fr = Fs /R

Transitional direction change

Figure 8.1 Magnitude of thrust (See Clause 8.6.2.7.1.)

8.6.2.7.2 Multi-strand tendons The lateral force, Fl, exerted by the bunching of strands of multi-strand post-tensioning tendons at the inside of the curved ducts shall be calculated as Fs /πR. Where the resistance provided by the concrete cover is less than the lateral forces, local confining reinforcement, which should be in the form of spirals, shall be provided throughout the curved tendon segment to resist the lateral forces.

8.6.2.7.3 Webs and flanges of box girders The flexure in the webs or flanges of box girders due to the forces in the plane of the tendon curvature or deviation may be calculated using an elastic frame analysis. Confinement reinforcement shall be provided around the ducts at each segment face for post-tensioning ducts located in the bottom flange of variable-depth segmental girders whose bottom flange consists of chords between segment joints. The reinforcement shall consist of at least two rows of 10M bars at both sides of each duct and shall extend the full depth of the flange minus the thickness of the top and bottom covers.

8.6.2.7.4 Stress in reinforcement The stress in the reinforcement to resist tension shall not exceed 240 MPa and the spacing of the reinforcement shall not exceed 250 mm.

8.6.2.7.5 Centre of gravity of tendons in ducts The eccentricity of curved tendons with respect to the duct shall be determined as shown in Figure 8.2.

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e CL of duct Centre of gravity of tendon Radius of curvature

Duct diameter, mm

e, mm

75 or less

12

Over 75 to 100

20

Over 100

25

Figure 8.2 Eccentricity of curved tendons (See Clause 8.6.2.7.5.)

8.6.3 Buckling Consideration shall be given to the buckling of precast components during handling and erection and to the buckling of thin webs and flanges. The effects of lateral eccentricity of loads shall be taken into account in determining the spacing of lateral restraints. However, unless a stability analysis is carried out, the spacing shall not exceed the lesser of 50b and 200(b2/ d) for beams. For cantilevers with lateral restraint only at the support, the clear distance from the end of the cantilever to the face of the support shall not exceed the lesser of 25b and 100(b2/ d).

8.7 Prestressing 8.7.1 Stress limitations for tendons Tendons shall be stressed to provide a minimum effective prestress of 0.45fpu . The stress in the tendons shall not exceed the values specified in Table 8.2.

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Table 8.2 Prestressing tendon stress limits (See Clause 8.7.1.) Tendon type High-strength bar

At jacking Pretensioning Post-tensioning At transfer Pretensioning Post-tensioning At anchorage and couplers Elsewhere

Low-relaxation strand

Smooth

Deformed

0.78fpu 0.80fpu

— 0.76fpu

— 0.75fpu

0.74fpu

—

—

0.70fpu 0.74fpu

0.70fpu 0.70fpu

0.66fpu 0.66fpu

8.7.2 Concrete strength at transfer The force in the tendons shall not be transferred to the concrete until the compressive strength of the concrete is at least 25 MPa for pretensioned components and at least 20 MPa for post-tensioned components.

8.7.3 Grouting After completion of post-tensioning, all internal and external ducts shall be grouted and load shall not be applied to or removed from the components until the grout has reached a compressive strength of at least 20 MPa.

8.7.4 Loss of prestress 8.7.4.1 General In the calculation of the prestress losses, the following shall be considered: (a) anchorage slip and friction; (b) elastic shortening of concrete; (c) relaxation of tendons; (d) creep of concrete; (e) shrinkage of concrete; and (f) any other special circumstances. In the calculation of time-dependent losses due to creep and shrinkage of concrete and relaxation of tendons, the interdependence of these phenomena, as well as the influence of non-prestressed reinforcement, shall be considered. For segmental construction, for components of low- or semi-low-density concrete, and where a more accurate estimate of losses is required, the calculation of prestress losses shall be based on a method supported by proven data. For multi-stage construction and multi-stage prestressing, the prestress losses shall be calculated by taking into consideration the elapsed time between each stage. In lieu of a more detailed analysis, the prestress losses at transfer, Δ fs1, and after transfer, Δ fs2 , for components constructed using normal-density concrete and single-stage prestressing shall be calculated in accordance with Clauses 8.7.4.2 and 8.7.4.3, respectively. The total loss considered, Δ fs , shall be taken as Δ fs1 + Δ fs2 .

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8.7.4.2 Losses at transfer 8.7.4.2.1 General

In lieu of a more accurate method, the total losses at transfer, Δ fs1, shall be taken as ANC + FR + REL1 + ES.

8.7.4.2.2 Anchorage slip The magnitude of the anchorage slip, ANC, shall be as required to control the stress in the tendons at transfer or as recommended by the manufacturer of the anchorage, whichever is greater. The magnitude of the slip shall be shown on the Plans.

8.7.4.2.3 Friction loss The loss due to friction between tendons and the sheath, FR, at a distance x from the jacking end shall be calculated as fsj (1 – e –(Kx + µα)). The values of K and µ shall be based on test data for the materials specified and shall be shown on the Plans. In the absence of such data, the values of K and µ specified in Table 8.3 may be used.

Table 8.3 Friction factors (See Clause 8.7.4.2.3.) Strand

Smooth bar

Deformed bar

Sheath type

K

µ

K

µ

K

µ

Internal ducts Rigid steel Semi-rigid steel over 75 mm outside diameter Semi-rigid steel up to 75 mm outside diameter Plastic

0.002 0.003 0.005 0.001

0.18 0.20 0.20 0.14

— — 0.003 —

— — 0.20 —

— — 0.003 —

— — 0.30 —

External ducts Straight plastic Rigid steel pipe deviators

0.000 0.002

— 0.25

— —

— —

— —

— —

8.7.4.2.4 Relaxation of tendons In pretensioned components, the relaxation loss, REL1, in low-relaxation tendons initially stressed in excess of 0.50fpu shall be calculated as follows:

REL1 =

⎤ log ( 24t ) ⎡ fsj − 0.55⎥ fsj ⎢ 45 ⎢⎣ fpy ⎥⎦

8.7.4.2.5 Elastic shortening The loss due to elastic shortening, ES, shall be calculated as follows: (a) pretensioned components:

ES =

Ep Eci

fcir

(b) post-tensioned components:

⎡ N − 1⎤ E p ES = ⎢ fcir ⎣ 2N ⎥⎦ Eci

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8.7.4.3 Losses after transfer 8.7.4.3.1 General

The losses after transfer, Δ fs2 , shall be taken as CR + SH + REL2 . If the ratio As /Aps is equal to or less than 1.0, the losses after transfer due to creep, shrinkage, and relaxation of tendons may be calculated in accordance with Clauses 8.7.4.3.2, 8.7.4.3.3, and 8.7.4.3.4, respectively. Otherwise, a more detailed analysis shall be performed.

8.7.4.3.2 Creep In lieu of a more accurate method, prestress losses due to creep, CR, may be calculated as follows:

Ep 2 CR = ⎡1.37 − 0.77 ( 0.01RH ) ⎤ K cr (fcir − fcds ) ⎣ ⎦ Ec where RH = annual mean relative humidity, %, as shown in Figure A3.1.3 Kcr

= 2.0 for pretensioned components and 1.6 for post-tensioned components

8.7.4.3.3 Shrinkage In lieu of a more accurate method, the loss of prestress due to shrinkage, SH, may be calculated as (117 – 1.05RH) for pretensioned components and (94 – 0.85RH) for post-tensioned components.

8.7.4.3.4 Relaxation of tendons In lieu of a more accurate method, loss of prestress due to relaxation after transfer, REL2 , may be calculated as follows for low-relaxation strand:

⎡f ⎤⎡ CR + SH ⎤ fpu ≥ 0.002fpu REL2 = ⎢ st − 0.55⎥ ⎢0.34 − ⎥ 1.25fpu ⎥⎦ 3 ⎢⎣ fpu ⎥⎦ ⎢⎣ For high-strength bars, the relaxation loss, REL2 , shall be based on Approved test data. In the absence of such data, REL2 shall be taken as 20 MPa.

8.8 Flexure and axial loads 8.8.1 General The requirements of Clauses 8.8.2 to 8.8.7 shall apply with respect to the proportioning of concrete components subjected to flexure or axial loads or both.

8.8.2 Assumptions for the serviceability and fatigue limit states In addition to the conditions of equilibrium and compatibility of strains, the following shall apply to calculations for the serviceability and fatigue limit states: (a) Concrete may be assumed to resist tension at sections that are uncracked, except as specified in Clause 8.8.6. (b) The stress in the concrete shall be assumed to be directly proportional to strain. (c) Strain in the concrete shall be assumed to vary linearly over the depth of the section, except for deep beams, where a non-linear distribution of strain shall be considered. (d) Strain changes in bonded reinforcement shall be assumed to be equal to strain changes in the surrounding concrete.

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(e) The transformed area of bonded reinforcement may be included in the calculation of section properties. Before grouting, the loss of concrete area due to post-tensioning ducts, coupler sheaths, or transition trumpets shall be considered, except where such loss of area is insignificant. The modular ratio, n, shall not be taken as less than 6. An effective modular ratio of 2n may be used to transform the compression reinforcement for stress computations corresponding to permanent loads.

8.8.3 Assumptions for the ultimate limit states In addition to the conditions of equilibrium and compatibility of strains, the calculations for the ultimate limit states shall be based on the material resistance factors specified in Clause 8.4.6 and the following shall apply to such calculations: (a) Strain in the concrete shall be assumed to vary linearly over the depth of the section, except for deep beams, which shall satisfy the requirements of Clause 8.10. (b) Strain changes in bonded reinforcement shall be assumed to be equal to strain changes in the surrounding concrete. (c) The maximum usable strain at the extreme concrete compression fibre shall be assumed to be 0.0035 unless the concrete is confined and a higher value of strain can be justified. In the latter case, a strain compatibility analysis shall be used. (d) Except for the strut-and-tie model of Clause 8.10, the stress in the reinforcement shall be taken as the value of the stress determined using strain compatibility based on a stress-strain curve representative of the steel reinforcement to be used, multiplied by  s or  p . (e) The tensile strength of the concrete shall be neglected in the calculation of the factored flexural resistance. (f) The relationship between concrete strain and the concrete compressive stress may be assumed to be rectangular, parabolic, or any other shape that results in a prediction of strength in substantial agreement with the results of comprehensive tests. In this regard, an equivalent rectangular concrete stress distribution may be used, i.e., a concrete stress of  1 cfc’ is uniformly distributed over an equivalent compression zone, bounded by the edges of the cross-section and a straight line parallel to the neutral axis at a distance a =  1c from the fibre of maximum compressive strain, where c is the shortest length between the fibre of maximum compressive strain and the neutral axis,   1 = 0.85 – 0.0015fc’  0.67 and  1 = 0.97 – 0.0025fc’  0.67.

8.8.4 Flexural components 8.8.4.1 Factored flexural resistance The factored flexural resistance shall be calculated in accordance with Clause 8.8.3.

8.8.4.2 Tendon stress at the ultimate limit states The value of fps for components with bonded tendons shall be computed using a method based on strain compatibility and using stress-strain curves representative of the steel, except that if c/dp is less than or equal to 0.5, the following expression may be used: fps = fpu (1 – kp c/dp ) where kp is 0.3 for low-relaxation strands, 0.4 for smooth high-strength bars, and 0.5 for deformed high-strength bars, and the value of c shall be determined assuming a stress of fps in the tendons. For components with unbonded tendons, fps shall be taken as fse unless a detailed analysis accounting for deformations demonstrates that a higher value can be used. External tendons shall be treated as unbonded tendons.

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8.8.4.3 Minimum reinforcement The total amount of reinforcement shall be such that the factored flexural resistance, Mr , of the component is at least 1.20 times the cracking moment. This requirement may be waived if the factored flexural resistance provided is at least one-third greater than the minimum resistance required for factored loads.

8.8.4.4 Cracking moment A component shall be assumed to crack when the moment at a section is such that a tensile stress of fcr , as specified in Clause 8.4.1.8, is induced in the concrete.

8.8.4.5 Maximum reinforcement The amount of reinforcement provided shall be such that the factored flexural resistance, Mr , is developed with c/d not exceeding 0.5. This requirement may be waived if it is demonstrated to the satisfaction of the Regulatory Authority that the consequences of reinforcement not yielding are acceptable. 

8.8.4.6 Prestressed concrete stress limitations The stresses in the concrete shall not exceed the following: (a) At transfer and during construction: (i) compression: 0.60fci’ ; (ii) tension in components without reinforcing bars in the tension zone: 0.50fcri . Where the calculated tensile stress exceeds 0.50fcri , reinforcing bars in which the tensile stress is assumed to be 240 MPa shall be provided to resist the total tensile force in the concrete, calculated on the basis of an uncracked section; and (iii) tension at joints in segmental components: (1) without reinforcing bars passing through the joint in the tension zone: zero; and (2) with reinforcing bars passing through the joint in the tension zone: 0.50fcri . Where the calculated tensile stress is between zero and 0.50fcri , reinforcing bars in which the tensile stress is assumed to be 240 MPa shall be provided to resist the total tensile force in the concrete calculated on the basis of an uncracked section. (b) At the serviceability limit states, if the tension in the concrete exceeds fcr , Clause 8.12 shall apply. Tension shall not be permitted across the joints of segmental components unless bonded reinforcing bars pass through the joints in the tensile zone. (c) In prestressed slabs with circular voids, the average compressive stress due to effective longitudinal prestress alone shall not exceed 6.5 MPa. In post-tensioned slabs with circular voids, the following shall apply: (i) an effective transverse prestress shall be provided to give a compressive stress of 4.5 MPa in the concrete above the longitudinal voids; and (ii) the thicknesses of the concrete above and below the voids shall not be less than 175 mm and 125 mm, respectively.

8.8.5 Compression components 8.8.5.1 General The proportioning of cross-sections subject to combined flexure and axial compression shall be in accordance with Clause 8.8.3.

8.8.5.2 Slenderness effects The proportioning of compression components shall be based on forces and moments determined from an analysis of the structure. Except as permitted by Clause 8.8.5.3, such an analysis shall include the influence of axial loads and variable moment of inertia on component stiffness and moments, the effect of deflections on the moments and forces, and the effects of the duration of the loads and prestressing forces.

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8.8.5.3 Approximate evaluation of slenderness effects In lieu of the requirements of Clause 8.8.5.2, the proportioning of non-prestressed compression components with a slenderness ratio, klu /r, less than 100, may be based on the following approximate procedure: (a) The unsupported length, lu , of a compression component shall be taken as the clear distance between components capable of providing lateral support for the compression component. (b) For components braced against side-sway, the effective length factor, k, shall be taken as 1.0 unless an analysis shows that a lower value can be used. For components not braced against side-sway, the effective length factor, k, shall be determined with due consideration of end restraint and the effects of cracking and reinforcement on relative stiffness, and shall not be taken as less than 1.0. (c) The radius of gyration, r, shall be calculated for the gross concrete section. (d) For components braced against side-sway, the effects of slenderness may be neglected when the slenderness ratio, klu /r, is less than [34 – 12(M1/M2)]. (e) For components not braced against side-sway, the effects of slenderness may be neglected when klu /r is less than 22. (f) Components in structures that do not undergo appreciable lateral deflections shall be proportioned using the factored axial load at the ultimate limit state and a magnified moment, Mc , calculated as follows: Mc = δ M 2 where

d =

Cm ⎡ P ⎤ 1− ⎢ f ⎥ ⎣ 0.75Pc ⎦ where

Pc =

≥ 1.0

π2EI

(k  u )2

In lieu of a more accurate calculation, E I may be taken as

EI =

0.2Ec I g + E sIs 1+ b d

or, conservatively, as 0.25Ec Ig . For components braced against side-sway, and without transverse loads between supports for the loading case under consideration, Cm may be taken as

Cm = 0.6 + 0.4

M1 ≥ 0.4 M2

For all other cases, Cm shall be taken as 1.0. (g) If calculations show that there is no moment at both ends of a compression component or that the calculated end eccentricities are less than (15 + 0.03h) mm, M2 shall be based on a minimum eccentricity of (15 + 0.03h) mm about each principal axis separately. When calculated end eccentricities are less than (15 + 0.03h) mm, calculated end moments shall be used to evaluate M1/M2. However, if calculations show that there is essentially no moment at both ends of a compression component, the ratio M1/M2 shall be taken as equal to 1.0. (h) For eccentrically prestressed components, consideration shall be given to the effect of lateral deflection due to prestressing in determining the magnified moment. (i) For components in structures that undergo appreciable lateral deflections resulting from combinations of vertical load or combinations of vertical and lateral loads, M1 and M2 shall be determined using a second-order analysis.

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8.8.5.4 Maximum factored axial resistance For components with spiral reinforcement, the factored axial resistance, Pr , shall be less than or equal to 0.80Po , and for components with tie reinforcement, shall be less than or equal to 0.75Po .

8.8.5.5 Biaxial loading In lieu of an analysis based on stress and strain compatibility for a loading condition of biaxial bending, non-circular components subjected to biaxial bending may be proportioned approximately in accordance with the following: (a) When the required factored axial resistance is equal to or greater than 0.10φ c fc’ Ag :

1 Prxy

=

1 1 1 + − Prx Pry Po

(b) When the required factored axial resistance is less than 0.10φ c fc’ Ag :

M x My + ≤1 Mrx Mry

8.8.5.6 Reinforcement limitations The maximum area of prestressed and non-prestressed longitudinal reinforcement shall be such that

As Apsfpu + ≤ 0.08 Ag Agfy and Apsfps Agfc′

≤ 0.30

The minimum area of prestressed and non-prestressed longitudinal reinforcement shall be such that

Asfy Agfc′

+

Apsfpu Agfc′

≥ 0.135

When the proportioning of compression components is controlled by considerations other than applied loading, the minimum area of longitudinal reinforcement shall be that required for a component with a reduced effective area of concrete capable of resisting the factored loads. The minimum number of longitudinal reinforcing bars shall be six for bars in a circular arrangement and four for bars in a rectangular arrangement. The minimum size of bar shall be 15M and the spacing shall not exceed 300 mm.

8.8.5.7 Transverse reinforcement Transverse reinforcement shall be provided in accordance with Clause 8.14.4.

8.8.5.8 Hollow rectangular components The wall slenderness ratio of a hollow rectangular cross-section, calculated as the larger internal plan dimension of the section divided by the wall thickness, shall not exceed 35. The resistance of a section with a wall slenderness ratio greater than 15 shall be reduced at a rate of 2.5% for each unit increase in the wall slenderness ratio above 15, to a maximum reduction of 25% at a wall slenderness ratio of 25. The reduction shall remain at this level up to a wall slenderness ratio of 35. Two layers of longitudinal and transverse reinforcement shall be provided in each wall of the cross-section, with one layer near each face of the wall and the two layers having approximately equal areas. The spacing of the longitudinal reinforcement shall comply with the requirements for walls and slabs in Clause 8.14.2.1.

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The transverse reinforcement shall comply with the requirements of Clause 8.14.4.3. Cross-ties shall be provided between layers of reinforcement in each wall. The cross-ties shall have a standard 135° hook at one end and a standard 90° hook at the other end and shall be located to enclose each longitudinal and transverse bar at a spacing not to exceed 600 mm.

8.8.6 Tension components For components in which the applied loading induces tensile stresses throughout the cross-section, the load shall be assumed to be resisted by the reinforcement alone when the tensile stress under serviceability limit state loads exceeds 0.6fcr . The requirements of Clause 8.12 shall apply. The amount of reinforcement shall be such that the factored axial tensile resistance is at least 1.20 times the load inducing a tensile stress of fcr in the concrete. Components subjected to eccentric tension loading that induces both tensile and compressive stresses in the cross-section shall comply with Clauses 8.8.2 to 8.8.4 and 8.12.

8.8.7 Bearing 8.8.7.1 Factored bearing resistance

The factored bearing resistance of concrete without transverse reinforcement shall be taken as 0.85φ c fc’ A1.

8.8.7.2 Bearing area The bearing area of a concrete component shall be taken as the loaded area A1, except that (a) when the supporting surface is wider on all sides than the loaded area, the factored bearing resistance may be multiplied by A 2 / A 1 , but not by a value greater than 2; and (b) when the supporting surface is sloped or stepped, A2 may be taken as the area of the lower base of the largest prismoid contained wholly within the support, having for its upper base the loaded area, and having side slopes of 1 vertical to 2 horizontal.

8.8.7.3 Bursting and spalling When the factored applied load exceeds that based on the bearing area permitted by Clause 8.8.7.2, adequate provision shall be made to resist the bursting and spalling forces in accordance with Clause 8.16.

8.9 Shear and torsion 8.9.1 General 8.9.1.1 Consideration of torsion Torsional effects shall be considered in regions where the factored torsional moment, Tf , is greater than 0.25Tcr , where 2 Acp ⎡ ⎤ fce Tcr = 0.80fc fcr ⎢1+ ⎥ pc ⎣ 0.80fc fcr ⎦

0.5

8.9.1.2 Regions requiring transverse reinforcement Except for solid slabs, walls, and footings, transverse reinforcement shall be provided in all regions where Vf is greater than (0.20φ c f cr bv dv + 0.5φ pVp ) and Tf is greater than 0.25Tcr .

8.9.1.3 Minimum amount of transverse reinforcement When calculations show that transverse shear reinforcement is required, Av shall not be less than 0.15fcr (bv s /f y). November 2006

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8.9.1.4 Design yield strength of transverse reinforcement The design yield strength of tendons used as transverse reinforcement shall be taken as the effective prestress plus 400 MPa, but shall not be taken greater than fpy .

8.9.1.5 Effective shear depth The effective shear depth, dv , shall be taken as the greater of 0.72h or 0.9d, where d is taken as the distance from the extreme compression fibre to the centroid of the longitudinal tension reinforcement in the half-depth of the section containing the flexural tension zone.

8.9.1.6 Effective web width The effective web width, bv , shall be taken as the minimum web width within the depth dv . In determining bv at a particular level, one-half the diameters of ungrouted ducts or one-quarter the diameters of grouted ducts at that level shall be subtracted from the web width. For solid circular sections, bv may be taken as the diameter.

8.9.1.7 Variable-depth components The resolved force components of inclined flexural compression and flexural tension in variable-depth components shall be taken into account when calculating shear resistance.

8.9.1.8 Reduced prestress within transfer length In pretensioned members, the reduction in prestress within the transfer length of prestressing tendons shall be considered when calculating Vp , fpo , and the tensile force that can be resisted by the longitudinal reinforcement. The prestress force may be assumed to vary linearly from zero at the point at which bonding commences to a maximum at a distance from the end of the tendon equal to the transfer length, assumed to be 50 diameters for strands and 100 diameters for single wires.

8.9.2 Design procedures 8.9.2.1 Flexural regions When it is reasonable to assume that plane sections remain plane, components shall be proportioned for shear and torsion using either the sectional design model specified in Clause 8.9.3 or the strut-and-tie model specified in Clause 8.10. In addition, the applicable requirements of Clause 8.9.1 shall be satisfied.

8.9.2.2 Regions near discontinuities When the plane sections assumption of flexural theory is not applicable, components shall be proportioned for shear and torsion using the strut-and-tie model specified in Clause 8.10. In addition, the applicable requirements of Clause 8.9.1 shall be satisfied.

8.9.2.3 Interface regions Interfaces between elements such as webs and flanges, between dissimilar materials, and between concretes cast at different times or at potential or existing major cracks shall be proportioned for shear transfer in accordance with Clause 8.9.5.

8.9.2.4 Slabs, walls, and footings With the exception of deck slabs, slab-type components subjected to concentrated loads shall be proportioned for shear in accordance with Clause 8.9.4 or 8.10.

8.9.2.5 Detailed analysis In lieu of the methods specified in Clauses 8.9.2.1 to 8.9.2.4, the resistance of components in shear or in shear combined with torsion may be determined by satisfying the applicable conditions of equilibrium and compatibility of strains, using appropriate stress-strain relationships for reinforcement and for diagonally cracked concrete.

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8.9.3 Sectional design model 8.9.3.1 Sections near supports Where the reaction force introduces compression into the end region of a component, the critical section for shear near the support shall be located at a distance of dv from the face of the support.

8.9.3.2 Required shear resistance Components subjected to shear shall be proportioned so that Vf is less than Vr .

8.9.3.3 Factored shear resistance The factored shear resistance, Vr , shall be calculated as Vc + Vs + Vp . However, Vc + Vs shall not exceed 0.25φc fc’ bv dv .

8.9.3.4 Determination of Vc

Vc shall be calculated as 2.5β φ c fcr bv dv . However, fcr shall not be greater than 3.2 MPa.

8.9.3.5 Determination of Vs Vs shall be determined as follows: (a) For components with transverse reinforcement perpendicular to the longitudinal axis, Vs shall be calculated as follows:

Vs =

fsfy Av dv cot q

s (b) For components with transverse reinforcement inclined at an angle to the longitudinal axis and in the direction that will intersect diagonal cracks caused by the shear, Vs shall be calculated as follows: Vs =

fsfy Av dv ( cot q + cot a ) sina s

8.9.3.6 Determination of β and θ for non-prestressed components (simplified method) For non-prestressed components not subjected to axial tension, and provided that the specified yield strength of the longitudinal reinforcement does not exceed 400 MPa and the design concrete strength does not exceed 60 MPa, the value of the angle of inclination, θ, shall be taken as 42° and the value of β shall be determined as follows: (a) For sections with at least the minimum amount of transverse reinforcement required by Clause 8.9.1.3, β shall equal 0.18. (b) For sections containing no transverse reinforcement located in footings where the distance from the point of zero shear to the face of the column, pedestal, or wall is less than 3dv , β shall equal 0.18. (c) For other sections not containing transverse reinforcement but having a specified nominal maximum size of coarse aggregate not less than 20 mm, β shall equal 230/(1000 + dv ). Alternatively, for sections containing no transverse reinforcement, β may be determined for all aggregate sizes as equal to 230/(1000 + sze ), where the equivalent crack spacing parameter, sze , is 35sz /(15 + ag ). However, sze shall not be taken as less than 0.85sz . As shown in Figure 8.3, the crack spacing parameter, sz , shall be taken as dv or as the distance between layers of distributed longitudinal reinforcement where each intermediate layer of such reinforcement has an area at least equal to 0.003b wsz .

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8.9.3.7 Determination of β and θ (general method) The value of β shall be calculated as follows:

⎡ ⎤⎡ ⎤ 0.4 1300 b=⎢ ⎥⎢ ⎥ ⎣ (1+ 1500e x ) ⎦ ⎣ (1000 + sze ) ⎦ For sections containing at least the minimum transverse reinforcement required by Clause 8.9.1.3, sze shall be taken as 300 mm; otherwise, sze shall be calculated in accordance with Clause 8.9.3.6. The value of ag in Clause 8.9.3.6 shall be taken as zero if fc‘ is greater than 70 MPa and shall be linearly equal to zero as fc‘ goes from 60 to 70 MPa. The angle of inclination, θ, shall be calculated as (29 + 7000εx)(0.88 + sze /2500). sz sin q

As > 0.003bwsz

sz q

(a) Component without transverse reinforcement but with well-distributed longitudinal reinforcement Flexural compression zone

sz sin q

sz > dv

q

(b) Component without transverse reinforcement and with concentrated longitudinal reinforcement

Figure 8.3 Influence of reinforcement on spacing of diagonal cracks (See Clause 8.9.3.6.)

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8.9.3.8 Determination of εx

In lieu of more accurate calculations, εx shall be calculated as follows:

ex =

Mf / dv + Vf − Vp + 0.5Nf − Aps fpo

(

2 E s As + E p Aps

)

Evaluation of this equation shall be based on the following: (a) Vf and Mf are positive quantities and Mf shall not be less than (Vf –Vp)dv . (b) Nf shall be taken as positive for tension and negative for compression. For rigid frames and rectangular culverts, the value of Nf used to determine εx may be taken as twice the compressive axial thrust calculated by elastic analysis. (c) As and Aps are the areas of reinforcing bars and prestressing tendons in the half-depth of the section containing the flexural tension zone. (d) fpo may be taken as 0.7fpu for bonded tendons outside the transfer length and fpe for unbonded tendons. (e) In calculating As , the area of bars that terminate less than their development length from the section under consideration shall be reduced in proportion to their lack of full development. (f) If the value of εx is negative, it shall be taken as zero or recalculated with the denominator replaced by 2(Es As + Ep Aps + Ec Act ). However, εx shall not be less than –0.20 × 10–3. (g) For sections closer than dv to the face of the support, the value of εx calculated at dv from the face of the support may be used in evaluating θ and β. (h) If the axial tension is large enough to crack the flexural compression face of the section, the resulting increase in εx shall be taken into account. In lieu of more accurate calculations, the value calculated from the equation shall be doubled. (i) θ and β may be determined from Clause 8.9.3.7 using a value of εx that is greater than that calculated from the equation in this Clause. However, εx shall not be greater than 3.0 × 10 –3.

8.9.3.9 Proportioning of transverse reinforcement Near locations where the spacing, s, of the transverse reinforcement changes, the quantity A v /s may be assumed to vary linearly over a length, h, centred on the location where the spacing changes.

8.9.3.10 Extension of longitudinal reinforcement At every section, the longitudinal reinforcement shall be designed to resist the additional tensile forces caused by shear as specified in Clauses 8.9.3.11 and 8.9.3.12. Alternatively, for members not subjected to significant tension or torsion, these requirements may be satisfied by extending the flexural tension reinforcement a distance of dv cotθ beyond the location required by flexure alone.

8.9.3.11 Longitudinal reinforcement on the flexural tension side Longitudinal reinforcement on the flexural tension side shall be proportioned so that at all sections the factored resistance of the reinforcement, taking account of the stress that can be developed in this reinforcement, is greater than or equal to Flt , calculated as follows:

Ft =

(

)

Mf + 0.5Nf + Vf − 0.5Vs − Vp cotq dv

where Mf and Vf are taken as positive quantities and Nf is positive for axial tension and negative for axial compression. In this equation, dv may be taken as the flexural lever arm at the factored resistance.

8.9.3.12 Longitudinal reinforcement on the flexural compression side Longitudinal reinforcement on the flexural compression side of the section shall be proportioned so that the factored tensile resistance of this reinforcement, taking account of the stress that can be developed in this reinforcement, shall be greater than or equal to the force Flc , calculated as follows:

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(

)

Fc = 0.5Nf + Vf − 0.5Vs − Vp cotq −

Mf dv

where Mf and Vf are taken as positive quantities and Nf is positive for axial tension and negative for axial compression.

8.9.3.13 Compression fan regions In regions adjacent to maximum moment locations, the cross-sectional area of longitudinal reinforcement on the flexural tension side of the member need not exceed the cross-sectional area required to resist the maximum moment acting alone. This exception shall apply only when the support or the load at the maximum moment location introduces direct compression into the flexural compression face of the member and the member is not subject to significant torsion.

8.9.3.14 Anchorage of longitudinal reinforcement at exterior supports At exterior direct-bearing supports, the longitudinal reinforcement on the flexural tension side for the member shall be capable of resisting a tensile force of (Vf – 0.5Vs – Vp) cot+ 0.5Nf , where Vs is based on the transverse reinforcement provided within a length of dv cotfrom the face of the support. However, Vs shall not be taken as greater than Vf . The tension force in the reinforcement shall be developed at the point where a line inclined at angle  to the longitudinal axis and extending from the inside edge of the bearing area intersects the centroid of the reinforcement.

8.9.3.15 Transverse reinforcement for combined shear and torsion For sections subjected to combined shear and torsion, the transverse reinforcement provided shall be at least equal to the sum of that required for shear and that required for the coexisting torsion.

8.9.3.16 Transverse reinforcement for torsion The amount of transverse reinforcement required for torsion shall be such that Tr is greater than or equal to Tf .

8.9.3.17 Factored torsional resistance The value of Tr shall be calculated as follows:

Tr = 2Ao

fs At fy s

cot q

where Ao is taken as 0.85Aoh and  is as specified in Clause 8.9.3.6 or 8.9.3.7. 

8.9.3.18 Cross-sectional dimensions to avoid crushing for combined shear and torsion The cross-sectional dimensions to avoid crushing for combined shear and torsion shall be as follows: (a) For box sections:

Vf − Vp bv dv

+

Tf ph ≤ 0.25fc fc′ 2 1.7Aoh

If the wall thickness of the box section is less than Aoh /ph , the second term in this expression shall be replaced by Tf /(1.7Aoht), where t is the wall thickness at the location where the stresses are being checked. (b) For other sections: 2

2

⎡ Tf ph ⎤ ⎡Vf − Vp ⎤ ≤ 0.25fc fc′ ⎢ ⎥ +⎢ 2 ⎥ ⎣ bv dv ⎦ ⎣ 1.7Aoh ⎦

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8.9.3.19 Determination of εx for combined shear and torsion

If β and θ and are determined using Clause 8.9.3.7, the value of εx for a section subjected to torsion shall be determined by the equation specified in Clause 8.9.3.8, but the term (Vf – Vp) in Clause 8.9.3.8(a) shall be replaced by

(

Vf − Vp

)

2

⎡ 0.9phTf ⎤ +⎢ ⎥ ⎣ 2Ao ⎦

2

8.9.3.20 Proportioning longitudinal reinforcement for combined shear and torsion The longitudinal reinforcement shall be proportioned to satisfy the requirements of Clauses 8.9.3.11 and 8.9.3.12, except that the term (Vf – 0.5Vs – Vp) in those clauses shall be replaced by

(

Vf − 0.5Vs − Vp

)

2

⎡ 0.45phTf ⎤ +⎢ ⎥ ⎣ 2Ao ⎦

2

8.9.4 Slabs, walls, and footings 8.9.4.1 Critical sections for shear In determining the shear resistance of slabs, walls, and footings in the vicinity of concentrated loads or reactions, the more severe of the following two actions shall govern: (a) beam action, with a critical section extending in a plane across the entire width and located at a distance, d, from the face of the concentrated load or reaction area, or from any change in slab thickness; and (b) two-way action, with a critical section perpendicular to the plane of the slab and located so that its perimeter, bo , is a minimum, but need not approach closer than 0.5d to the perimeter of the concentrated load or reaction area. Shear resistance shall also be investigated at critical sections located at a distance not closer than 0.5d from any change in slab thickness and located such that the perimeter, bo , is a minimum.

8.9.4.2 Beam action For beam action, the shear resistance shall be calculated in accordance with Clause 8.9.3.3.

8.9.4.3 Two-way action For two-way action, the shear resistance shall be such that Vr is greater than Vf , where Vr = (φ c fcr + 0.25fpc )bod + Vp

8.9.5 Interface shear transfer 8.9.5.1 General A crack shall be assumed to occur along the shear plane and the relative displacement shall be considered to be resisted by cohesion and friction maintained by the shear-friction reinforcement crossing the crack. In lieu of more detailed calculations, the shear resistance of the plane, v, may be calculated as φ c (c + µσ ), but v shall not exceed 0.25φ c fc‘ or 6.5 MPa. c and µ shall be as specified in Clause 8.9.5.2 and σ shall be as specified in Clause 8.9.5.3.

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8.9.5.2 Values of c and µ 8.9.5.2.1 The following values shall be taken for c and µ in Clause 8.9.5.1: (a) For concrete placed against hardened concrete, with the surface clean and free of laitance but not intentionally roughened, c shall equal 0.25 MPa and µ shall equal 0.60λ1. (b) For concrete placed against hardened concrete, with the surface clean and free of laitance and intentionally roughened to a full amplitude of about 5 mm and a spacing of about 15 mm, c shall equal 0.50 MPa and µ shall equal 1.00λ1. (c) For concrete placed monolithically, c shall equal 1.00 MPa and µ shall equal 1.40λ1. The values of λ1 shall be as specified in Clause 8.9.5.2.2.

8.9.5.2.2 Values of λ 1

The values of λ1 shall be as follows: (a) normal-density concrete: 1; (b) semi-low-density concrete: 0.85; and (c) low-density concrete: 0.75.

8.9.5.3 Value of σ

The value of σ in Clause 8.9.5.1 shall be calculated as follows:

s = rv fy +

N Acv

where

rv =

Avf Acv

8.9.5.4 Anchorage of shear-friction reinforcement The shear-friction reinforcement shall be capable of developing the specified yield strength of the reinforcement on both sides of the shear-friction plane.

8.10 Strut-and-tie model 8.10.1 General Strut-and-tie models may be used to determine internal force effects near supports and the points of application of concentrated loads. Strut-and-tie models shall be considered for the design of deep footings and pile caps or other situations in which the distance between the centres of applied load and the supporting reaction is less than twice the component thickness.

8.10.2 Structural idealization The strength of concrete structures, components, or regions shall be investigated by idealizing them as a series of reinforcing steel tensile ties and concrete compressive struts interconnected at nodes to form a truss capable of carrying all of the factored loads to the supports. In determining the geometry of the truss, account shall be taken of the required dimensions of the compressive struts and tensile ties.

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8.10.3 Proportioning of a compressive strut 8.10.3.1 Strength of strut The dimensions of the strut shall be large enough to ensure that the calculated compressive force in the strut does not exceed  c Acsfcu , where Acs and fcu are determined in accordance with Clauses 8.10.3.2 and 8.10.3.3, respectively.

8.10.3.2 Effective cross-sectional area of strut The value of Acs shall be calculated by considering both the influence of the anchorage conditions at the ends of the strut, as shown in Figure 8.4, and the available concrete area. £ 6dba

a sinqs

£ 6dba

x

dba

qs

s

6dba

6dba

dba

a

x

x–x

(a) Strut anchored by reinforcement

b sinqs + ha cosqs qs

b

hs

ha

0.5ha b

qs

b sinqs + hs cosqs

(b) Strut anchored by bearing and reinforcement

(c) Strut anchored by bearing and strut

Figure 8.4 Influence of anchorage conditions on effective cross-sectional area of strut (See Clause 8.10.3.2.)

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8.10.3.3 Limiting compressive stress in strut The value of fcu shall be calculated as follows:

fcu =

fc′ ≤ a1fc′ 0.8 + 170e1

where 1 is calculated as  s + ( s + 0.002) cot2s , in which  s is the smallest angle between the compressive strut and the adjoining tensile ties and  s is the tensile strain in the tensile tie inclined at  s to the compressive strut.

8.10.3.4 Reinforced strut If the compressive strut contains reinforcement that is parallel to the strut and has been detailed to develop its yield stress in compression, the calculated force in the strut shall not exceed  c fcu Acs +  s fy Ass . The strut shall be reinforced with lateral ties in accordance with Clause 8.14.4.3.

8.10.4 Proportioning of a tension tie 8.10.4.1 Strength of tie The cross-sectional area of the reinforcement in a tension tie shall be large enough to ensure that the calculated tensile force in the tie does not exceed  s fy Ast +  p fpy Aps , where Ast is the cross-sectional area of the reinforcing bars in the tie and Aps is the cross-sectional area of the tendons in the tie.

8.10.4.2 Anchorage of tie The tension tie reinforcement shall be anchored so that it is capable of resisting the calculated tension in the reinforcement at the inner edge of the node region. For straight bars extending a distance x beyond the inner edge of the node region, where x is less than d , the calculated stress shall not exceed f y ( x/d), where d is calculated in accordance with Clause 8.15.2.

8.10.5 Proportioning of node regions 

8.10.5.1 Stress limits in node regions Unless special confining reinforcement is provided, the calculated concrete compressive stress in the node regions shall not exceed the following (with1, as specified in Clause 8.8.3): (a) 1 c fc’ in node regions bounded by compressive struts and bearing areas; (b) 0.881 c f’c in node regions anchoring a tension tie in only one direction; and (c) 0.761 cf’c in node regions anchoring tension ties in more than one direction.

8.10.5.2 Satisfying stress limits in node regions The stress limits in node regions may be considered satisfied if the following two conditions are met: (a) the bearing stress in the node regions produced by concentrated loads or reactions does not exceed the stress limits specified in Clause 8.10.5.1; and (b) the tensile tie reinforcement is uniformly distributed over an effective area of concrete at least equal to the tensile tie force divided by the stress limits specified in Clause 8.10.5.1.

8.10.6 Crack control reinforcement Except for slabs and footings, components or regions that have been designed in accordance with Clauses 8.10.1 to 8.10.5 shall contain an orthogonal grid of reinforcing bars near each face. The spacing of this reinforcement shall not exceed 300 mm. The ratio of reinforcement area to gross concrete area shall not be less than 0.003, but the reinforcement need not be more than 1500 mm2/m in each face and in each direction. If located within the tension tie, the crack control reinforcement may also be considered tension tie reinforcement.

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8.11 Durability 8.11.1 Deterioration mechanisms The deterioration mechanisms to be considered for concrete components shall include, but not be limited to, the following: (a) carbonation-induced corrosion without chloride; (b) chloride-induced corrosion due to seawater; (c) chloride-induced corrosion from sources other than seawater; (d) freeze-thaw deterioration; (e) alkali aggregate reaction; (f) chemical attack; and (g) abrasion.

8.11.2 Protective measures 8.11.2.1 Concrete quality 8.11.2.1.1 General The maximum water to cementing materials ratio by mass requirements for structural concrete shall be as specified in Table 8.4 for the applicable combination of deterioration mechanisms and environmental exposures. For structural concrete not covered by Table 8.4, the maximum water to cementing materials ratio shall be 0.50 unless otherwise Approved.

Table 8.4 Maximum water to cementing materials ratio (See Clause 8.11.2.1.1.) Deterioration mechanism

Environmental exposure

Maximum ratio*†‡

Chloride-induced corrosion

Marine Airborne salts Tidal and splash spray Submerged

0.45 0.45 0.40

Other than marine Wet, rarely dry Dry, rarely wet Cyclic, wet/dry

0.40 0.40 0.40

Freeze-thaw attack§

Unsaturated Saturated

0.45 0.40

Carbonation-induced corrosion without chloride

Wet, rarely dry Dry, rarely wet Cyclic, wet/dry

0.50 0.50 0.45

*Unless otherwise Approved. †Water to cementing materials ratio by mass. Cementing materials include Portland cement, silica fume, fly ash, and slag. ‡The ratio shall be independently verified on the submitted concrete mix design and concrete materials. Quality control and quality assurance measures shall be taken to ensure uniformity of concrete production so that water/cement limits are maintained throughout production. Such measures shall include measurements of slump, air content, unit weight, and strength. §Air content shall be in accordance with CAN/CSA-A23.1. The minimum air content shall be 5.5% for concrete in saturated conditions unless otherwise Approved. November 2006

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8.11.2.1.2 Concrete composition The concrete composition shall be such that the concrete (a) satisfies all specified performance criteria; (b) contains durable materials; (c) can be placed, compacted, and cured to form a dense cover to the reinforcement; (d) is free of harmful internal reactions, e.g., alkali-aggregate reactions; (e) withstands the action of freezing and thawing, including the effects of de-icing salts (where applicable); (f) withstands external exposures, e.g., weathering, gases, liquids, and soil; and (g) withstands mechanical attacks, e.g., abrasion.

8.11.2.1.3 Concrete placement The maximum and minimum allowable concrete placement temperatures to ensure durable concrete shall be shown on the Plans.

8.11.2.1.4 Compaction The methods used for mixing, placing, and compacting the fresh concrete shall be shown on the Plans to ensure that (a) the constituents are distributed uniformly in the mixture; (b) the concrete is well consolidated; and (c) the reinforcement, pretensioning strands, and post-tensioning ducts are not damaged by vibrating operations.

8.11.2.1.5 Cold joints The concrete surface at a cold joint shall be rough cleaned, abrasive blast cleaned, or both. Coated bars at cold joints shall be protected during abrasive blast cleaning.

8.11.2.1.6 Slip-form construction The slip-form construction for reinforced concrete components shall not be permitted unless Approved.

8.11.2.1.7 Finishing The methods to be used for finishing the surface of the concrete to ensure a durable surface shall be shown on the Plans.

8.11.2.1.8 Curing The methods to be used for curing the concrete to ensure durability shall be shown on the Plans.

8.11.2.1.9 Exposure to chlorides Chlorides shall not be added to fresh concrete and the concrete components shall not be exposed to chlorides until the concrete has attained the specified minimum strength.

8.11.2.2 Concrete cover and tolerances The minimum concrete cover and tolerances for steel reinforcement, pretensioning strands, and post-tensioning ducts shall not be less than the values specified in Table 8.5 for the applicable environmental exposure. The minimum cover and tolerances for anchorages and mechanical connections shall be those specified for reinforcing steel in Table 8.5. The applicable concrete covers and tolerances shall be shown on the Plans.

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8.11.2.3 Corrosion protection for reinforcement, ducts, and metallic components Unless otherwise Approved, steel reinforcement, anchorages, and mechanical connections specified for use within 75 mm of a surface exposed to moisture containing de-icing chemicals shall have an Approved protective coating, be protected by other Approved methods of corrosion protection or prevention, or be of non-corrosive materials. Exposed inserts, fasteners, and plates shall be protected from corrosion by Approved methods. Sheaths for internal post-tensioning ducts specified for use within 100 mm of a surface subject to moisture containing de-icing chemicals shall be made of non-corroding material or with an Approved coating. The ends of pretensioning strands shall be protected by Approved methods when they are not encased in concrete.

8.11.2.4 Sulphate-resistant cements Sulphate-resistant cement shall be specified for concrete in deep foundation units, footings, buried structures made of reinforced concrete, or other substructure components exposed to soils or water to an extent sufficient to cause a strong sulphate attack on concrete. Protection against sulphate attack shall be in accordance with CAN/CSA-A23.1.

8.11.2.5 Alkali-reactive aggregates Aggregates for concrete shall be tested for susceptibility to alkali aggregate reaction. The evaluation and use of aggregates susceptible to alkali aggregate reaction shall be in accordance with CAN/CSA-A23.1 and CAN/CSA-A23.2-27A.

8.11.2.6 Drip grooves Continuous drip grooves shall be formed on the underside of the bridge deck. The grooves shall be located close to the fascia and shall have minimum dimensions for depth and width of 20 mm and 50 mm, respectively. At expansion joints without joint armouring, the end of the concrete deck slab shall be provided with a drip groove. If joint armouring is provided, it shall cover the end of the deck slab and extend at least 50 mm below the concrete in order to form a drip projection.

8.11.2.7 Waterproofing Unless otherwise Approved, concrete decks that are expected to be salted for winter maintenance or are exposed to a marine environment shall be waterproofed with an Approved waterproofing system.

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Table 8.5 Minimum concrete covers and tolerances



(See Clause 8.11.2.2.) Concrete covers and tolerances Environmental exposure De-icing chemicals; spray or surface runoff containing de-icing chemicals;

Component

Reinforcement/ steel ducts

Cast-in-place Precast concrete, mm concrete, mm

(1)

Top of bottom slab for rectangular voided deck

Reinforcing steel Pretensioning strands Post-tensioning ducts

40 ± 10 — 60* ± 10

40 ± 10 55 ± 5 60* ± 10

(2)

Top surface of buried structure with less than 600 mm fill† Top surface of bottom slab of buried structure

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

50 ± 10 65 ± 5 70* ± 10

(3)

Top surface of structural component, except (1)  and (2) above‡

Reinforcing steel Pretensioning strands

70 ± 20 —

55 ± 10

130* ± 15 90* ± 15

120* ± 10 80* ± 10

130* ± 15

120* ± 10

Reinforcing steel Pretensioning strands Reinforcing steel Pretensioning strands Post-tensioning ducts

— — 50 ± 10 — 70* ± 10

40 ± 10 38 ± 3 45 ± 10 60 ± 5 65* ± 10

marine spray

Post-tensioning ducts Longitudinal Transverse (dd  60 mm Transverse (dd > 60 mm )

70 ± 5

(4)

Soffit of precast deck form

(5)

Soffit of slab less than 300 mm thick or soffit of top slab of voided deck

(6)

Soffit of slab 300 mm thick or thicker or soffit of structural component, except (4) and (5) above

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 10 — 80* ± 10

50 ± 10 65 ± 5 70* ± 10

(7)

Vertical surface of arch, solid or voided deck, pier cap, T-beam, or interior diaphragm

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 10 — 90* ± 10

60 ± 10 75 ± 5 80* ± 10

(8)

Inside vertical surface of buried structure or inside surface of circular buried structure

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

50 ± 10 65 ± 5 70* ± 10

(9)

Vertical surface of structural component, except (7) and (8) above

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

55 ± 10 70 ± 5 75* ± 10

Reinforcing steel Pretensioning strands Post-tensioning ducts

— — —

35 +10 or –5 50 ± 5 55* ± 10

(10) Precast T-, I-, or box girder

(Continued)

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Table 8.5 (Continued) Concrete covers and tolerances Environmental exposure Component

Reinforcement/ steel ducts

Cast-in-place Precast concrete, concrete, mm mm

No de-icing chemicals; no spray or surface runoff containing de-icing chemicals; no marine spray

(1)

Top of bottom slab for rectangular voided deck

Reinforcing steel Pretensioning strands Post-tensioning ducts

40 ± 10 — 60* ± 10

40 ± 10 55 ± 5 60* ± 10

(2)

Top surface of buried structure with less than 600 mm fill† or top surface of bottom slab of buried structure

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 20 — 80* ± 15

40 ± 10 55 ± 5 60* ± 10

(3)

Top surface of structural component, except (1) and (2) above‡

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 20 — 80* ± 15

50 ± 10 70 ± 5 70 ± 10

(4)

Soffit of precast deck form

Reinforcing steel Pretensioning strands

— —

40 ± 10 38 ± 3

(5)

Soffit of slab less than 300 mm thick or soffit of top slab of voided deck

Reinforcing steel Pretensioning strands Post-tensioning ducts

40 ± 10 — 60* ± 10

40 ± 10 55 ± 5 60* ± 10

(6)

Soffit of slab 300 mm thick or thicker or soffit of structural component, except (4) and (5) above

Reinforcing steel Pretensioning strands Post-tensioning ducts

50 ± 10 — 70* ± 10

40 ± 10 55 ± 5 60* ± 10

(7)

Vertical surface of arch, solid or voided deck, pier cap, T-beam, or interior diaphragm

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 10 — 80* ± 10

50 ± 10 65 ± 5 70* ± 10

(8)

Inside vertical surface of buried structure or inside surface of circular buried structure

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 20 — 80* ± 15

40 ± 10 55 ± 5 60* ± 10

(9)

Vertical surface of structural component, except (7) and (8) above

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 20 — 80* ± 15

50 ± 10 70 ± 5 70* ± 10

Reinforcing steel Pretensioning strands Post-tensioning ducts

— — —

30 +10 or –5 45 ± 5 50* ± 10

(10) Precast T-, I-, or box girder

(Continued)

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Table 8.5 (Concluded) Concrete covers and tolerances Environmental exposure Component

Reinforcement/ steel ducts

Cast-in-place Precast concrete, concrete, mm mm

Earth or fresh water

Swamp, marsh, salt water, or aggressive backfill

(1)

Footing, pier, abutment, or retaining wall

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

55 ± 10 75 ± 5 80* ± 10

(2)

Concrete pile

Reinforcing steel Pretensioning strands Post-tensioning ducts

— — —

40 ± 10 55 ± 5 60* ± 10

(3)

Caisson with liner

Reinforcing steel Post-tensioning ducts

60 ± 20 80* ± 15

(4)

Buried structure with more than 600 mm of fill†

Reinforcing steel Pretensioning strands Post-tensioning ducts

60 ± 20 — 80* ± 15

40 ± 10 55 ± 5 60* ± 10

(1)

Footing, pier, abutment, or retaining wall

Reinforcing steel Pretensioning strands Post-tensioning ducts

80 ± 20 — 100* ± 15

65 ± 10 85 ± 10 90* ± 10

(2)

Concrete pile

Reinforcing steel Pretensioning strands Post-tensioning ducts

— — —

50 ± 10 65 ± 5 70* ± 10

(3)

Caisson with liner

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

(4)

Buried structure with more than 600 mm of fill†

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20 — 90* ± 15

Footing

Reinforcing steel

100 ± 25

—

Caisson

Reinforcing steel Post-tensioning ducts

100 ± 25 120 ± 15

— —

Reinforcing steel Pretensioning strands Post-tensioning ducts

70 ± 20§ — 90* ± 15§

Cast against and (1) permanently exposed to earth (2) Various

Components other than those covered elsewhere in this Table

— —

— — — 55 ± 10 70 ± 5 80* ± 10

55 ± 10§ 70 ± 5§ 80* ± 10§

*Or 0.5d , whichever is greater. d †Buried structures with less than 600 mm of fill shall have a distribution slab. ‡For concrete decks without waterproofing and paving, increase the concrete cover by 10 mm to allow for wearing of the surface concrete. §Or as Approved.

8.11.3 Detailing for durability 8.11.3.1 Reinforcement detailing Reinforcement shall be spaced or grouped to facilitate the placing and compaction of concrete.

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8.11.3.2 Confining reinforcement cage Pretensioned and post-tensioned tendons shall be confined in an outer reinforcement cage, where practical.

8.11.3.3 Debonding of pretensioned strands Pretensioned strands shall not be debonded at the ends of girders unless the ends are protected by Approved methods.

8.12 Control of cracking 8.12.1 General The requirements of Clauses 8.12.2 to 8.12.6 shall apply with respect to the distribution of reinforcing bars and tendons to control cracking.

8.12.2 Distribution of reinforcement Bonded reinforcing bars and, where applicable, tendons, shall be uniformly distributed within the tensile zone as close to the extreme tension fibre as cover and spacing requirements permit. Reinforcing bars shall also be provided at the side faces of beams in accordance with Clause 8.12.4.

8.12.3 Reinforcement 8.12.3.1 Maximum crack width Crack widths at serviceability limit states shall not exceed the values specified in Table 8.6 for the applicable type of structural component and exposure.

Table 8.6 Maximum crack width (See Clause 8.12.3.1.) Type of structural component Non-prestressed

Prestressed

Type of exposure

Maximum crack width, mm

De-icing chemicals; spray or surface runoff containing de-icing chemicals; marine spray; swamp; marsh; salt water; aggressive backfill

0.25

Other environmental exposures

0.35

De-icing chemicals; spray or surface runoff containing de-icing chemicals; marine spray; swamp; marsh; salt water; aggressive backfill

0.15

Other environmental exposure

0.20

8.12.3.2 Calculation of crack width

Crack width, w, shall be taken as kb β c srm εsm . kb shall be taken as 1.2 for components with epoxy-coated reinforcing steel and 1.0 for all other components. When cracking is caused by load, βc shall be taken as 1.7. When cracking is caused by superimposed deformations, βc shall be taken as 1.7 for cross-sections with a minimum dimension exceeding of 800 mm and 1.3 for cross-sections with a minimum dimension of

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300 mm or less. Linear interpolation may be used to calculate βc for cross-sections with a minimum dimension between these limits. srm shall be calculated as follows (in millimetres):

srm = 50 + 0.25kc

db rc

kc shall be taken as 0.5 for bending and 1.0 for pure tension. ρc is the ratio As /Act , where Act is the effective tension area of the concrete cross-section and As is the area of reinforcement contained within Act . The depth of Act shall be taken as the lesser of (a) 2.5 times the distance from the extreme tensile fibre of the cross-section to the centroid of tensile reinforcement; and (b) one-third the distance from the neutral axis of the cross-section to the extreme tensile fibre. εsm shall be calculated as follows:

e sm

2 fs ⎡ ⎡ fw ⎤ ⎤ = ⎢1− ⎢ ⎥ ⎥ E s ⎢ ⎣ fs ⎦ ⎥ ⎣ ⎦

where fs is stress in reinforcement at the serviceability limit state and fw is stress in reinforcement under the conditions causing initial cracking. Both fs and fw shall be calculated on the basis of a cracked section.

8.12.4 Crack control in the side faces of beams Note: This Clause does not apply to prestressed components in which the minimum prestress is such that the cracks due to the application of live load remain closed under permanent load effects.

Where the overall depth of a beam exceeds 750 mm, longitudinal reinforcement with a total area not less than 0.01bwd shall be evenly distributed over both faces of the web over a distance of 70% of the overall depth from the tension face, at a spacing of not more than 200 mm. The value of bw used to calculate the area of reinforcement need not be greater than 250 mm. This reinforcement may be included in strength calculations if a strain compatibility analysis is conducted to determine the stresses in the individual bars.

8.12.5 Flanges of T-beams For flanges of T-beams subjected to flexural tension exceeding fcr , the reinforcing bars shall be uniformly distributed over an effective flange width as specified in Clause 5.8.2 or over a flange width equal to 10% of the span, whichever is smaller. If the effective flange width exceeds 10% of the span, additional longitudinal reinforcement shall be provided in the outer portions of the flange.

8.12.6 Shrinkage and temperature reinforcement Reinforcement for shrinkage and temperature crack control normal to the principal reinforcement shall be provided in structural components where the principal reinforcement extends in one direction only. At all sections where it is required, such reinforcement shall be developed in accordance with Clause 8.15.2. The minimum area of shrinkage and temperature reinforcement in each face and in each direction shall be 500 mm2/m and the spacing of the bars shall not exceed 300 mm.

8.13 Deformation 8.13.1 General Dimensional changes, deflections, and rotations occurring immediately upon the application of loads shall be determined in accordance with elastic methods using the value of Ec at the time of loading and taking into consideration the effects of cracking and reinforcement.

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8.13.2 Dimensional changes Dimensional changes due to loads, temperature, shrinkage, and creep shall be determined using the data specified in Clauses 8.4.1.3, 8.4.1.5, and 8.4.1.6.

8.13.3 Deflections and rotations 8.13.3.1 General Deflections and rotations shall be calculated in accordance with one of the methods specified in Clauses 8.13.3.2 to 8.13.3.4.

8.13.3.2 Refined method Determination of deflection and rotation of a member by a refined method shall make allowance for the the following, as applicable: (a) shrinkage and creep properties of the concrete; (b) relaxation of prestressing steel; (c) expected load history; and (d) effects of cracking and tension stiffening.

8.13.3.3 Simplified method Deflections and rotations may be calculated using the effective moment of inertia, Ie , as follows:

(

Ie = Icr + I g − Icr

)

3

⎡ Mcr ⎤ ⎢ ⎥ ≤ Ig ⎣ Ma ⎦

For prestressed concrete, the value of Mcr /Ma to be used in calculating deflections and rotations due to live load shall be taken as

(f − f ) Mcr = 1− tl cr Ma fI For continuous spans, the effective moment of inertia may be taken as the average for the critical positive and negative moment sections. For prismatic members, the effective moment of inertia may be taken as the value at midspan for simple spans and at the support for cantilevers.

8.13.3.4 Total deflection and rotation In lieu of a more refined analysis, the sum of the total instantaneous and long-term deflection and rotation for flexural non-prestressed components may be obtained by multiplying, respectively, the instantaneous deflection and rotation caused by the sustained load by the factor

⎡ ⎤ S ⎢1+ ⎥ ′ ⎣ 1+ 50 r ⎦ where ρ ‘ shall be taken as the value at midspan for simple and continuous spans and at the support for cantilevers. The factor S for duration of sustained loads shall be taken as follows: (a) three months: 1; (b) six months: 1.2; (c) 12 months: 1.4; and (d) five years or more: 2. If necessary, linear interpolation may be used for durations of less than five years. In lieu of a more refined analysis, the long-term deflection and rotation of flexural prestressed components may be estimated by multiplying, respectively, the instantaneous deflection and rotation due November 2006

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to loads and prestress by appropriate factors. The total deflection and rotation may be estimated by adding the instantaneous and the long-term deflection and rotation, respectively.

8.14 Details of reinforcement and special detailing requirements 8.14.1 Hooks and bends 8.14.1.1 Standard hooks The standard hooks specified in Clauses 8.14.1.2 and 8.15.5 shall consist of (a) a semi-circular bend plus an extension of at least four bar diameters but not less than 60 mm at the free end of the bar; (b) a 90° bend plus an extension of at least twelve bar diameters at the free end of the bar; or (c) for stirrup and tie anchorage only, either a 90° or a 135° bend plus an extension of at least six bar diameters at the free end of the bar.

8.14.1.2 Minimum bend diameter The diameter of a bend measured on the inside of a bar for standard hooks, except for stirrup and tie hooks, shall not be less than the applicable value specified in Table 8.7.

Table 8.7 Minimum bend diameter, mm (See Clause 8.14.1.2.) Type of reinforcement Bar

300R

400R or 500R

400W or 500W

Epoxy coated

10M 15M 20M 25M 30M 35M 45M 55M

60 90 — — — — — —

70 100 120 150 250 300 450 600

60 90 100 150 200 250 400 550

80 120 160 200 240 350 450 550

8.14.1.3 Stirrups and tie hooks The inside diameter of bends and 90° and 135° hooks for stirrups and ties shall not be less than four bar diameters for uncoated bars and eight bar diameters for epoxy-coated bars. The inside diameter of bends in plain or deformed welded wire fabric for stirrups and ties shall be not less than four wire diameters for deformed wire larger than 7 mm and two wire diameters for all other wires, except that bends with an inside diameter of less than eight wire diameters shall be not less than four wire diameters from the nearest welded intersection.

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8.14.2 Spacing of reinforcement 8.14.2.1 Reinforcing bars 8.14.2.1.1 For cast-in-place concrete, the clear distance between parallel bars in a layer or a ring shall not be less than (a) 1.5 times the nominal diameter of the bars; (b) 1.5 times the maximum size of the coarse aggregate; and (c) 40 mm.

8.14.2.1.2 For precast concrete, the clear distance between parallel bars in a layer or a ring shall not be less than (a) the nominal diameter of the bars; (b) 1.33 times the maximum size of the coarse aggregate; and (c) 25 mm.

8.14.2.1.3 For parallel reinforcing bars placed in two or more layers, with a clear distance between layers of not more than 150 mm, the bars in the upper layers shall be placed directly above those in the lower layers (except in deck slabs). The clear distance between layers shall not be less than (a) 25 mm; and (b) the nominal diameter of the bars.

8.14.2.1.4 The clear distance limitation between bars shall also apply to the clear distance between a contact lap splice and adjacent splices or bars.

8.14.2.1.5 In walls and slabs, primary flexural reinforcement shall be spaced not farther apart than (a) 1.5 times the thickness of the component; and (b) 450 mm. The maximum spacing of hoops, spirals, ties and shrinkage, and temperature reinforcement shall satisfy Clauses 8.12.6, 8.14.3, and 8.14.4.

8.14.2.2 Tendons 8.14.2.2.1 Pretensioning The centre-to-centre spacing between pretensioning strands at the ends of the members shall not be less than 50 mm. Pretensioning strands may be bundled, provided that a minimum of 50 mm spacing is maintained at the end of the member. Groups of up to eight strands may be bundled to touch one another in a vertical plane. The number of strands bundled in any other manner shall not exceed four. The clear distance between groups of bundled strands shall not be less than 1.33 times the maximum size of the aggregate or 25 mm, whichever is greater.

8.14.2.2.2 Post-Tensioning The clear distance between post-tensioning ducts shall not be less than 40 mm. For groups of ducts in the same horizontal plane, the clear horizontal distance between each group shall not be less than 100 mm. A group shall contain not more than three ducts. For groups of ducts in two or more horizontal planes, the clear horizontal distance between adjacent groups shall not be less than 100 mm. A group shall contain not more than two ducts in the same horizontal plane. November 2006

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For precast or cast-in-place segmental construction, the clear horizontal distance between groups of ducts may be reduced to 75 mm.

8.14.3 Transverse reinforcement for flexural components Where compression reinforcement for flexural components is required by analysis, the reinforcement shall be confined by closed stirrups. The stirrups shall be at least 10M when the longitudinal bars are 30M or smaller and at least 15M when the longitudinal bars are larger than 30M. Welded wire fabric of equivalent area may be used for closed stirrups. The spacing of the stirrups shall not exceed (a) 16 times the diameter of the longitudinal bar; (b) the least dimension of the component; and (c) 300 mm. For hollow rectangular components that meet the requirements of Clause 8.8.5.8, the spacing of the stirrups shall also not exceed 1.25 times the wall thickness. For specified concrete strength exceeding 60 MPa, the spacing of the stirrups shall be reduced by 25%. None of the longitudinal bars shall be farther than 150 mm from the leg of a confining stirrup. Closed stirrups may be formed in one piece by overlapping the hooks of standard stirrups around a longitudinal bar, or formed in one or two pieces lap-spliced with a minimum lap of 1.3ld.

8.14.4 Transverse reinforcement for compression components 8.14.4.1 General The longitudinal reinforcement for wall-type compression components need not be enclosed by lateral ties if the reinforcement area is not greater than 0.01 times the gross concrete area or when analysis shows that longitudinal reinforcement is not required as compression reinforcement.

8.14.4.2 Spirals Spiral reinforcement for compression components shall consist of evenly spaced continuous spirals held firmly in place by attachment to the longitudinal reinforcement and by spacers. The spirals shall be of a size that permits handling and placing without distortion from the specified dimensions. Anchorage of spiral reinforcement shall be provided by one and one-half extra turns of spiral bar at each end of the spiral unit embedded in the footing and the component supported above the footing, or by a 90° bend around a longitudinal reinforcing bar plus an extension of at least 24 bar diameters into the core. Splices in spiral bars shall be provided by one of the following means: (a) complete joint penetration groove welds meeting the requirements of CSA W186; (b) mechanical connections meeting the requirements of Clause 8.4.4.4; (c) ends of spiral bars anchored around a longitudinal reinforcing bar with extensions of at least 24 bar diameters into the core; or (d) an Approved method. Spiral reinforcement shall extend over the full length of the compression component. The maximum centre-to-centre spacing shall not exceed six times the diameter of the longitudinal bars or 150 mm, whichever is less. The clear spacing shall not be less than 25 mm and not less than 1.33 times the maximum size of the coarse aggregate. The ratio of spiral reinforcement, ρ s , shall not be less than the following value:

⎡ Ag ⎤f′ ⎡ P ⎤ rs = 0.45 ⎢ − 1⎥ c ⎢0.5 + 1.25 f ⎥ fc fc′Ag ⎥⎦ ⎣ Ac ⎦ fy ⎢⎣

8.14.4.3 Ties In tied compression components, all bars shall be enclosed by ties. The size and spacing of these ties shall meet the requirements for stirrups in Clause 8.14.3, except that the spacing may be increased for compression components that have a larger cross-section than required by the conditions of loading, in

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which case the maximum spacing shall not exceed 450 mm. Welded wire fabric of equivalent area may be used for ties. Ties shall be arranged so that every corner bar and alternate longitudinal bar has lateral support provided by the corner of a tie having an included angle of not more than 135°, and no bar shall be farther than 150 mm clear on either side from such a laterally supported bar. Ties shall be located vertically not more than half a tie spacing above the footing or from other support, and not more than half a tie spacing below the lowest horizontal reinforcement in the components supported above.

8.14.5 Reinforcement for shear and torsion 8.14.5.1 Transverse reinforcement Transverse reinforcement shall consist of one of the following forms: (a) stirrups perpendicular to the axis of the component or at an angle of 45° or more to the longitudinal tension reinforcement, with the inclined stirrups oriented to intercept potential cracks; (b) well-anchored tendons that are detailed and constructed to minimize seating and time-dependent losses and are perpendicular to the axis of the component or at an angle of 45° or more to the longitudinal tension reinforcement, with the inclined tendons oriented to intercept potential diagonal cracks; (c) spirals; or (d) welded wire fabric, with the wires perpendicular to the axis of the component. Transverse reinforcement for shear shall be anchored in accordance with Clause 8.15.1.5.

8.14.5.2 Torsional reinforcement Torsional reinforcement shall consist of longitudinal reinforcement and one of the following forms of transverse reinforcement: (a) closed stirrups perpendicular to the axis of the component and anchored with 135° hooks; (b) a closed cage of welded wire fabric perpendicular to the axis of the component; or (c) spirals. 

8.14.6 Maximum spacing of reinforcement for shear and torsion

If Vf is less than or equal to (0.10cfc’bv dv + Vp) and Tf is less than or equal to 0.25Tcr , the spacing of the transverse reinforcement, s, measured in the longitudinal direction, shall not exceed the lesser of 600 mm or 0.75dv . If Vf exceeds (0.10c fc’bv dv + Vp), or if Tf exceeds 0.25Tcr , s shall not exceed the lesser of 300 mm or 0.33dv . The spacing of longitudinal bars for torsion distributed around the perimeter of the stirrups shall not exceed 300 mm. At least one longitudinal bar with a diameter not less than 0.06 times the spacing of the stirrups and not smaller than 15M shall be placed inside each corner of the closed stirrups. The corner bars shall be anchored in accordance with Clause 8.15.2 or 8.15.5.

8.15 Development and splices 8.15.1 Development 8.15.1.1 General The calculated tension or compression in the reinforcement at each section shall be developed on each side of that section by one or more of embedment length, end anchorage, and a hook or mechanical device. Hooks or mechanical devices may be used in developing the strength of the bars in tension only.

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Tension reinforcement may be anchored by extending it into the compression zone or bending it and making it continuous with the reinforcement on the opposite face of the member. Reinforcement shall extend beyond the point at which it is theoretically no longer required to resist flexure in accordance with the requirements of Clause 8.9.3.10. The value of fc′ in Clause 8.4.1.8 used to compute fcr in Clauses 8.15.2.2, 8.15.2.3, 8.15.3.1, 8.15.5.2, and 8.15.7.2 shall not exceed 8.0.

8.15.1.2 Positive moment reinforcement At least 33% of the positive moment reinforcement in simply supported members and 25% of the positive moment reinforcement in continuous members shall extend along the same face of the member into the support. Such reinforcement shall extend at least 150 mm beyond the centreline of the exterior support and shall satisfy the requirements of Clause 8.9.3.10. When a flexural member is part of the lateral-load-resisting system, the positive moment reinforcement required to be extended into the support shall be anchored so as to develop the yield strength in tension at the face of the support.

8.15.1.3 Negative moment reinforcement Negative moment reinforcement in a continuous, restrained, or cantilever member, or any member of a rigid frame, shall be anchored in or through the supporting member by embedment length, hooks, or mechanical anchorage. At least 33% of the total reinforcement provided for negative moment at the support shall have an embedment length beyond the point of inflection not less than the effective depth of the member, 12db , or 0.06 of the clear span, whichever is greatest.

8.15.1.4 Special members Adequate end anchorage shall be provided for tension reinforcement in flexural members where stress in the reinforcement is not directly proportional to moment. Such members include, but are not limited to, sloped, stepped, or tapered footings, brackets, deep beams, and members in which the tension reinforcement is not parallel to the compression face.

8.15.1.5 Anchorage of transverse reinforcement Transverse reinforcement provided for shear shall extend as close to the compression and tension surfaces of the member as cover requirements and the proximity of other reinforcement permit. Transverse reinforcement provided for shear shall be anchored at both ends by one of the following: (a) For 15M and smaller bars and MD200 and smaller wire, a standard hook, as specified in Clause 8.14.1.1, around longitudinal reinforcement. (b) For 20M and 25M stirrups, a standard hook, as specified in Clause 8.14.1.1, around longitudinal reinforcement, plus an embedment between mid-depth of the member and the outside end of the hook equal to or greater than 0.33d . (c) For each leg of welded smooth wire fabric forming single U-stirrups, (i) two longitudinal wires running at a 50 mm spacing along the member at the top of the U; or (ii) one longitudinal wire located not more than 0.25d from the compression face and a second wire closer to the compression face and spaced not less than 50 mm from the first. The second wire may be located on the stirrup leg beyond a bend or on a bend with an inside diameter of not less than 8db . (d) For each end of a single leg stirrup of welded smooth or deformed wire fabric, two longitudinal wires at a minimum spacing of 50 mm, with the inner wire at least 0.25d from the mid-depth of the member. The outer longitudinal wire at the tension face shall not be farther from that face than the portion of primary flexural reinforcement closest to the face. (e) A mechanical anchor capable of developing the yield strength of the bar. Pairs of U-stirrups or ties placed so as to form a closed unit shall be considered properly spliced when lapped for a length of 1.3d . In components with a depth of at least 450 mm, such splices having Abfy not

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more than 40 kN per leg may be considered adequate if the stirrup legs extend the full available depth of the component. Between the anchored ends, each bend in the continuous portion of a transverse single U-stirrup or multiple U-stirrup shall enclose a longitudinal bar.

8.15.2 Development of reinforcing bars and deformed wire in tension 8.15.2.1 General The development length, ld , of reinforcing bars and deformed wire in tension shall be determined from Clause 8.15.2.2 or 8.15.2.3, but shall not be less than 300 mm, except as specified in Clause 8.15.2.5.

8.15.2.2 Development length The development length, ld , of reinforcing bars and deformed wire in tension shall be calculated as follows:

 d = 0.45

k1k2k3 ⎡ fy (dcs + Ktr ) ⎢⎣ fcr

⎤ ⎥ Ab ⎦

where Ktr

=

0.45

Atr fy 10.5sn

where s

= maximum centre-to-centre spacing of transverse reinforcement within a distance ld and the factor 10.5 is expressed in millimetres per newton

However, the term (dcs + Ktr ) shall not be taken greater than 2.5db .

8.15.2.3 Simplified development length The development length, ld , of reinforcing bars and deformed wire in tension may be taken from Table 8.8 if the clear cover and clear spacing of the bars being developed are at least db and 1.4db , respectively.

Table 8.8 Minimum development length of reinforcing bars and deformed wire in tension (See Clause 8.15.2.3.)

Cases Components containing minimum stirrups or ties (Clause 8.9.1.3 or 8.14.4.3) within ld or slabs and walls with a clear spacing of not less than 2db between bars being developed Other cases

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Minimum development length, ld

0.18k1k2k3

0.24k1k2k3

fy fcr fy fcr

db

db

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8.15.2.4 Modification factors The following modification factors shall be used in calculating the development length specified in Clauses 8.15.2.2 and 8.15.2.3: (a) Bar location factor, k1: (i) 1.3 for horizontal reinforcement placed so that more than 300 mm of fresh concrete is cast in the component below the development length or splice; and (ii) 1.0 for other cases. (b) Coating factor, k2: (i) 1.5 for epoxy-coated reinforcement with a clear cover less than 3db or a clear spacing between bars being developed less than 6db ; (ii) 1.2 for all other epoxy-coated reinforcement; and (iii) 1.0 for uncoated reinforcement. (c) Bar size factor, k3: (i) 0.8 for 20M and smaller bars and deformed wires; and (ii) 1.0 for 25M and larger bars. The product k1k2 need not be taken greater than 1.7.

8.15.2.5 Modification factors for excess reinforcement The development length, ld , may be multiplied by the factor (As required)/(As provided) where reinforcement in a flexural member exceeds that required by analysis, except where anchorage or development for fy is specifically required or the reinforcement is proportioned in accordance with Clause 8.17.

8.15.3 Development of reinforcing bars in compression 8.15.3.1 The development length, ld , for reinforcing bars in compression shall be calculated as follows:

d =

0.10fy db fcr

but shall not be less than 0.044fy db and not less than 200 mm. The units of the constant 0.044 shall be taken as the reciprocal of MPa.

8.15.3.2 The development length, ld , may be multiplied by one or both of the applicable modification factors specified in Table 8.9. The cumulative value shall be not less than 0.6.

Table 8.9 Modification factors for development length (See Clause 8.15.3.2.)

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Condition

Modification factor

Reinforcement exceeding that required by analysis

(As required)/(As provided)

Reinforcement enclosed within spirals at least 6 mm in diameter and with a pitch of not more than 100 mm, or within 10M ties in accordance with Clause 8.14.4.3 and spaced not more than 100 mm on centre

0.75

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8.15.4 Development of pretensioning strand Pretensioning strand shall be bonded beyond the critical section for a development length of not less than ld , calculated as follows:

 d = 1.5

fsi db − 117 + 0.18 fps − fse db fci′

(

)

Where bonding of the strand does not extend to the ends of the component and tension occurs at the serviceability limit state within the development length, ld , a development length of 2ld shall be used. The number of strands where the bonding does not extend to the ends of the member shall not exceed 25% of the total number of strands.

8.15.5 Development of standard hooks in tension 8.15.5.1 General The development length, ldh , for reinforcing bars in tension terminating in a standard hook shall be calculated as the product of the basic development length, lhb , specified in Clause 8.15.5.2 and the applicable modification factor or factors specified in Table 8.10. The development length ldh shall be not less than 8db or 150 mm, whichever is greater.

8.15.5.2 Basic development length The basic development length for a hooked bar, lhb , shall be calculated as 40db /fcr .

8.15.5.3 Factors modifying hook development length The basic development length, lhb , shall be multiplied by the applicable modification factor or factors specified in Table 8.10.

Table 8.10 Modification factors for hook development length (See Clauses 8.15.5.1 and 8.15.5.3.) Condition

Modification factor

Bars with fy other than 400 MPa

fy /400

35M or smaller bars where the side cover normal to plane of the hook is greater than 60 mm; 90° hooks where the cover on the bar extension beyond the hook is greater than 50 mm

0.7

35M or smaller bars where the hook is confined by at least three ties or stirrups with a spacing not greater than 3db along a length at least equal to the inside diameter of the hook, where db is the diameter of the hooked bar

0.8

Reinforcement exceeding that required by analysis, provided that anchorage or development to attain fy is not specifically required

(As required)/(As provided)

Epoxy-coated reinforcement

1.2

For bars being developed by a standard hook at the ends of components where both the side cover and the top or bottom cover over the hook are less than 60 mm, the hook shall be enclosed within at least three ties or stirrups with a spacing of not greater than 3db along a length at least equal to the inside diameter of the hook, where db is the diameter of the hooked bar. For this case, the factor of 0.8 in Table 8.10 shall not apply. November 2006

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8.15.6 Combination development length The development length, ld , may consist of a combination of the equivalent embedment length of a hook or mechanical anchorage plus the additional embedment length of the reinforcement measured from the point of tangency of the hook.

8.15.7 Development of welded wire fabric in tension 8.15.7.1 Deformed wire fabric The development length, ld , of welded deformed wire fabric measured from the point of critical section to the end of the wire shall be calculated as the product of the development length specified in Clause 8.15.2.2 or 8.15.2.3 and the applicable wire fabric factor specified in this Clause, but ld shall not be less than 200 mm except for lap splices, which shall be in accordance with Clause 8.15.9.5. For welded deformed wire fabric with at least one cross-wire within the development length not less than 50 mm from the point of critical section, the wire fabric factor shall be the greater of (fy – 240)/fy and 5db /sw , but need not be taken greater than 1.0. For welded deformed wire fabric with no cross-wires within the development length, or with a single cross-wire less than 50 mm from the point of critical section, the wire fabric factor shall be taken as 1.0.

8.15.7.2 Smooth wire fabric The yield strength of welded smooth wire fabric shall be considered developed by embedment of two cross-wires, with the closer cross-wire not less than 50 mm from the point of critical section. However, the development length, ld , measured from the point of critical section to the outermost cross-wire shall not be less than 1.30Aw fy /sw fcr , modified by the ratio for reinforcement exceeding that required by analysis, but shall not be taken less than 150 mm, except for the calculation of lap splices in accordance with Clause 8.15.9.6.

8.15.8 Mechanical anchorages Reinforcement may be developed by a mechanical anchorage device of the type specified in Clause 8.4.4.2.

8.15.9 Splicing of reinforcement 8.15.9.1 Lap splices Lap splices shall not be used for bars larger than 35M. Bars spliced by non-contact lap splices in flexural members shall not be spaced transversely farther apart than (a) 0.20 times the required lap splice length; and (b) more than 150 mm.

8.15.9.2 Welded splices A welded splice shall have bars welded to develop, in tension, at least 120% of the specified yield strength, fy , of the bar, but not less than 110% of the mean yield strength representative of the bars to be used in the test of the welded splice.

8.15.9.3 Splices of deformed bars and deformed wire in tension Lap splices of deformed bars and deformed wire in tension shall be classified as Class A or Class B in accordance with Table 8.11. The minimum length of lap shall be 1.0ld for Class A splices and 1.3ld for Class B splices, but not less than 300 mm. In this regard, the development length, ld , shall be calculated in accordance with Clause 8.15.2.1, but without the modification factors for excess reinforcement specified in Clause 8.15.2.5.

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Table 8.11 Classification of lap splices in tension (See Clause 8.15.9.3.) Maximum percentage of As spliced within required splice length (As provided)/(As required)

50

100

≥2 5 m. For the orthogonal arrangement of reinforcing bars in interior regions, minimum ρ = 0.003.

Figure 8.6 Reinforcement for cast-in-place deck slabs designed using the empirical method (See Clause 8.18.4.2.)

Equal reinforcement ratio based on effective depth of slab

Cast-in-place topping

Pretensioning strand or non-prestressed reinforcement

Precast panel Effective depth of slab

Figure 8.7 Reinforcement for cast-in-place deck slabs on precast panels (See Clause 8.18.4.3.1.)

8.18.4.3.2 Partial-depth precast panels For the empirical design method to apply, partial-depth precast panels acting compositely with the cast-in-place topping and the supporting beams shall be designed to satisfy the following conditions in addition to those of Clause 8.18.4.1: (a) The design takes handling and construction methods into account. (b) The effective span is taken as the distance between the edges of flanges of the supporting beams plus 150 mm. (c) The thickness of the panel is not more than 0.55h. (d) The pretensioning strands or reinforcing bars are located at the mid-depth of the panel. (e) In addition to the transverse strands or reinforcing bars, the panel contains 10M longitudinal reinforcing bars at a maximum spacing of 400 mm or a reinforcement mesh with a cross-sectional area of 230 mm2/m width in the longitudinal direction of the bridge. (f) For pretensioned panels, the compressive and tensile stresses in the concrete during construction do not exceed 0.6 fc‘ and fcr , respectively (assuming the strand-placing tolerances specified in Clause 8.11.2.2). November 2006

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(g) The effective span of a precast panel with only non-prestressed reinforcement does not exceed 2.0 m. (h) The deflection of a panel during construction does not exceed (i) 15 mm; and (ii) 1/240 of the effective span of the panel. (i) The top surface of a panel is clean and free of laitance and intentionally roughened to a full amplitude of about 2 mm at about 15 mm centres. (j) The ends of a panel are supported on the beams in such a manner that, after placement of the concrete topping, a continuous bedding support at least 75 mm wide is provided over the full length of the beams, and such support is within 25 mm of the edges of the beam flanges. (k) For pretensioned panels, the transfer and development length of the strands accounts for the anticipated conditions during construction.

8.18.4.4 Full-depth precast panels For the empirical design method to apply, the full-depth precast panels shall satisfy the following conditions in addition to those of Clause 8.18.4.1 and, as applicable, Clause 8.18.4.2: (a) the panels cover the full width of the bridge; (b) the depth of the panels is not less than 190 mm; (c) at their transverse joints, the panels are joined together by grouted shear keys and are longitudinally post-tensioned with a minimum effective prestress of 1.7 MPa; (d) the ducts for longitudinal post-tensioning are located at the mid-depth of the panels, and openings (also known as blockouts) are provided at the joints to accommodate splices for tendons; (e) blockouts are provided in the panels at locations where the panels are to be connected to the beams for composite action; (f) initially, the panels are supported on the beams by means of temporary levelling devices, with the blockouts for connections to beams for composite action and the gap between the panels and beams being filled with grout after completion of post-tensioning; and (g) the grout used in the shear keys has a minimum strength of 35 MPa at 24 h.

8.18.5 Diaphragms The decks slabs of all continuous-span bridges shall have cross-frames or diaphragms extending throughout the cross-section at intermediate support lines. Steel I-girders supporting deck slabs designed in accordance with the empirical design method of Clause 8.18.4 shall have intermediate cross-frames or diaphragms at a spacing of not greater than 8.0 m centre-to-centre. Deck slabs on box girders shall have intermediate diaphragms or cross-frames at a spacing not exceeding 8.0 m centre-to-centre between the boxes. Alternatively, deck slabs may contain reinforcement over the internal webs additional to that required by the empirical method (to provide for the global transverse bending due to eccentric loads).

8.18.6 Edge stiffening The transverse free edges of all deck slabs shall be stiffened by composite edge beams and shall be proportioned for the effects of wheel loads. Where the unsupported length of an edge stiffening beam, Se , is less than or equal to 5 m and the slab is designed in accordance with Clause 8.18.4, the details as shown in any one of the diagrams of Figure 8.8 may be considered satisfactory.

8.18.7 Distribution reinforcement The distribution reinforcement for slabs analyzed using elastic methods in accordance with Section 5 shall be placed transverse to the main reinforcement. The amount of distribution reinforcement for the main reinforcement parallel to traffic, as a percentage of the main reinforcement, shall be 55/(S)0.5, up to a maximum of 50%. When the main reinforcement is perpendicular to traffic, the amount of the distribution reinforcement shall be 120/(S)0.5, up to a maximum of 67%. In the outer quarter of the span it may be reduced to one-half of the calculated amount.

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Three 25M bars (fully anchored reinforcement)

As = 0.028t2

t Se /9

Slab reinforcement End reinforcement (same size and spacing as longitudinal slab reinforcement) 500 mm

Three 25M bars (fully anchored reinforcement) Three 25M bars (fully anchored reinforcement)

Two 15M bars

t

Se /12

200 mm 300 mm

Two 15M bars

Slab reinforcement End reinforcement (same size and spacing as longitudinal slab reinforcement) Minimum C200 x 21 with two 22 mm diameter x 100 mm long stud connectors per row. Stud spacing at least same as longitudinal slab reinforcement. Web of channel connected to top flange of supporting beams. Three 25M bars (fully anchored reinforcement) t

Se /12

Slab reinforcement End reinforcement (same size and spacing as longitudinal slab reinforcement) Minimum W200 x 52 with two 22 mm diameter x 100 mm long stud connectors per row. Stud spacing at least same as longitudinal slab reinforcement. Top flange of beam connected to top flange of supporting beams. 200 mm 300 mm As = 0.008bd (fully anchored reinforcement) t

Se/12

Slab reinforcement End reinforcement (same size and spacing as longitudinal slab reinforcement)

d (500 mm min.)

As = 0.028t2 As = 0.008bd (fully anchored reinforcement) b (300 mm min.)

Figure 8.8 Edge stiffening at transverse free edges (See Clause 8.18.6.) November 2006

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8.19 Composite construction Note: This Clause applies to flexural components constructed in separate placements and interconnected in such a manner that they respond to loads as an integral unit.

8.19.1 General Precast concrete units shall be proportioned to support all loads applied before the cast-in-place concrete attains a strength of 0.75fc‘.

8.19.2 Flexure When the components used in composite construction have different specified strengths, stresses at the serviceability limit state shall be calculated on the basis of the respective moduli of elasticity. Differential shrinkage between cast-in-place and precast concrete shall be considered in the design of composite components at the serviceability limit state. A differential shrinkage strain of 100 × 10–6 shall be assumed unless more accurate data are available. The factored resistance of a composite section shall be calculated in the manner used for a monolithically cast unit.

8.19.3 Shear The factored shear resistance of a composite section shall be calculated in accordance with Clause 8.9.3.3. Interface shear shall be investigated and provided for in accordance with Clause 8.9.5.

8.19.4 Semi-continuous structures 8.19.4.1 General The effects of creep and shrinkage shall be considered when structural continuity is assumed in calculating live load and superimposed dead load effects in bridges composed of simply supported girders that are precast, prestressed, and made continuous by providing tensile reinforcement in the cast-in-place deck slabs and diaphragms over the girder supports.

8.19.4.2 Positive moments When the age of girders at the time of introducing continuity can be predicted and controlled, the positive moment reinforcement over the supports shall be proportioned for structural continuity to resist the moments due to creep, shrinkage, temperature change, and live load in remote spans. The effects of deformation and settlement of piers shall also be considered. The stress in the reinforcement shall be limited to 240 MPa at serviceability limit states. When the age of girders at the time of introducing continuity cannot be predicted and controlled, the superimposed dead load and live load moments shall be determined from an analysis that accounts for the lack of positive moment continuity. Minimum positive moment reinforcement having an area at least 1.50 times the nominal depth of the precast component shall be provided in the bottom flanges over the supports (with the units of both the multiplier of 1.50 and the depth in millimetres). The reinforcement shall be adequately embedded in the bottom flange of the girders beyond the strand transfer length and anchored into the diaphragm over the continuity supports.

8.19.4.3 Negative moments The negative moment at the supports shall be calculated based on the assumption of full structural continuity. The effect of precompression due to prestress in the girders shall be neglected in calculating the negative flexural resistance within the strand transfer length. The ratio of the continuity reinforcement, ρ , in the deck slab shall not exceed 0.5 times the ratio that would produce balanced strain conditions for the composite section.

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8.20 Concrete girders 8.20.1 General In box girders and T-girders, there shall be full transfer of shear forces at the interface of the girder webs and the top and bottom flanges. Proportioning for interface shear shall be in accordance with Clause 8.9.5. Changes in the thickness of the web of a girder shall be achieved by tapering for a minimum distance of twelve times the difference in web thickness.

8.20.2 Effective flange width for T- and box girders The effective flange width shall be as specified in Clause 5.8.2.

8.20.3 Flange thickness for T- and box girders 8.20.3.1 Top flange The thickness of the top flange shall be as specified in Clause 8.18.2 and not less than the following: (a) for cast-in-place T- and box girders: 0.05 times the clear distance between the webs; and (b) for precast T- and box girders: (i) 125 mm; and (ii) 0.03 times the clear distance between the webs. Where the top flanges of precast T- and box girders act compositely with a cast-in-place concrete topping, the flange thickness limit shall be that for cast-in-place girders and shall be based on the total thickness.

8.20.3.2 Bottom flange The thickness of the bottom flange shall not be less than the following: (a) for cast-in-place girders: (i) 150 mm; and (ii) 0.06 times the clear distance between the webs; and (b) for precast girders: (i) 100 mm; and (ii) 0.03 times the clear distance between the webs.

8.20.3.3 Fillets For cast-in-place girders, fillets with dimensions of at least 100 × 100 mm shall be provided at the intersections of all interior surfaces. They may, however, be omitted at the junction of the web and bottom flange of a box girder.

8.20.4 Isolated girders Isolated girders in which the T-form is used for providing additional compression area shall have a flange thickness at least equal to 0.3 times the web width or 100 mm, whichever is greater.

8.20.5 Top and bottom flange reinforcement for cast-in-place T- and box girders In each flange, reinforcement with a minimum area of 0.004 times the flange area shall be placed parallel to the girder span (for prestressed components, however, a minimum reinforcement of 0.003 times the flange area shall be used). Such reinforcement shall be distributed near both surfaces of the flange. The spacing of the reinforcement shall not exceed 300 mm. In each flange, reinforcement with a minimum area of 0.005 times the transverse cross-sectional area of the flange based on the least corresponding flange thickness shall be placed transverse to the girder span. Such reinforcement shall be distributed near both surfaces of the flange. The maximum spacing of the reinforcement shall be 300 mm. All transverse reinforcement in the bottom flange of box girders shall extend over the width of the girder and shall be adequately anchored. November 2006

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8.20.6 Post-tensioning tendons Ducts for post-tensioning shall be located within the stirrups in webs and, where applicable, between layers of transverse reinforcing in flanges and slabs. The effect of grouting pressure in the ducts shall be considered. Curved tendons shall meet the requirements of Clause 8.6.2.7. In the top and bottom flanges of box sections where ducts for post-tensioning are spaced closer than 300 mm, the top and bottom reinforcement mats shall be tied together with vertical reinforcement consisting of 10M hairpin bars with a spacing not exceeding 300 mm in each direction.

8.20.7 Diaphragms Diaphragms shall be provided at abutments and piers. The diaphragms shall be proportioned to transfer loads to the supports and to allow for future jacking of the girders. Intermediate diaphragms shall be provided if required for improving load distribution or for stability during construction.

8.21 Multi-beam decks Multi-beam decks consisting of precast units placed side by side shall have a means for live load shear transfer between the units. Shear transfer may be achieved by (a) a 150 mm thick concrete structural slab. The transverse shear in the slab shall be calculated in accordance with Section 5 and the concrete slab shall be reinforced to resist this shear in accordance with Clause 8.9.5; (b) grouted shear keys in combination with lateral post-tensioning providing a prestress of not less than 1.7 MPa, after all losses, over a compressed depth of joint not less than 175 mm; or (c) an Approved means capable of live load shear transfer between the units.

8.22 Segmental construction 8.22.1 General Clause 8.22 applies to post-tensioned girders made of match-cast or cast-in-place concrete segments. The cross-section may consist of single or multi-cell box segments or beam-type segments. The box segments may be transversely prestressed and the beam-type segments may be pretensioned. The erection and construction loads shall be as specified in Section 3. Stresses due to the changes in the structural system, in particular the effects of the application of a load to one system and its removal from a different system, shall be accounted for. Redistribution of force effects due to creep shall be taken into account and allowance made for possible variations in the creep rate and magnitude.

8.22.2 Additional ducts and anchorages 8.22.2.1 General Provision shall be made for the introduction of additional post-tensioning to compensate for excessive friction losses during construction and for future strengthening of the bridge.

8.22.2.2 During construction Segmental box girder bridges with internal tendons shall have additional anchorages and ducts capable of accommodating tendons with a capacity equal to at least 5% of the positive and negative moment post-tensioning forces, respectively. The ducts shall be located symmetrically about the bridge centreline and the anchorages shall be distributed uniformly at three segment intervals along the length of the bridge. At least one additional duct per web with adequate anchorage shall be provided. For continuous bridges, the additional positive moment ducts and anchorage capacity need not be provided along 25% of the span length on either side of an intermediate support. All additional ducts not used during construction shall be grouted at the same time as other ducts in the span.

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8.22.2.3 Future strengthening Provision shall be made for access, anchorages, deviators, and openings along the box girder cells to permit addition of external tendons located symmetrically about the bridge centreline for future strengthening. In this regard, provision shall be made for at least 10% of the positive moment post-tensioning forces and at least 10% of the negative moment post-tensioning forces.

8.22.3 Diaphragms Diaphragms shall be provided at abutments, piers, and locations of abrupt angular changes of the soffit of the girders. Provision shall be made in the diaphragms for openings for access, future strengthening, and utilities.

8.22.4 Deviators for external tendons 8.22.4.1 Design and detailing Deviators shall consist of deviation blocks or diaphragms. The design of the deviators shall be based on the specified strength of the tendons. Localized flexural effects in the web and flange shall be considered. Reinforcement shall be provided in the form of reinforcing bars anchored in the web and flange. The development length shall be measured from the tendon axis and the reinforcement shall be mechanically anchored around longitudinal reinforcing bars.

8.22.4.2 Localized effects The transverse force effects at the deviation blocks due to unsymmetrical geometry and sequence of post-tensioning shall be considered and shall be resisted by post-tensioning or by reinforcing bars proportioned for a stress not exceeding 240 MPa.

8.22.5 Coupling of post-tensioning tendons Not more than 50% of the tendons in a member shall be coupled at the same section. The distance between couplers of adjacent tendons shall not be less than the segment length and not less than twice the segment depth.

8.22.6 Special provisions for various bridge types 8.22.6.1 Precast segmental 8.22.6.1.1 General Precast segmental bridges shall be designed to be erected in accordance with one of the following methods: (a) balanced cantilever; (b) span-by-span; or (c) progressive placement. The minimum age of the segments at the time of erection shall be 14 d unless otherwise Approved.

8.22.6.1.2 Joints Precast segments shall be match cast and erected with epoxied joints. The minimum thickness of epoxy shall be 2 mm on each surface if applied to both surfaces or 3 mm if applied to one surface. A minimum compressive stress of 350 kPa shall be provided over the entire cross-sectional area between precast segments by temporary post-tensioning until the permanent tendons are fully stressed.

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8.22.6.1.3 Shear keys At the joints, shear keys incorporating corrugations shall be providing in the webs. The spacing of the corrugations shall be four times their depth. The corrugations shall be not less than 30 mm deep and shall extend for as much of the web width and depth as practicable. Interface shear resistance shall be calculated in accordance with Clause 8.9.5. Keys in the top and bottom flanges for alignment of segments during erection shall also be provided. These may be large single-element keys.

8.22.6.2 Cast-in-place segmental 8.22.6.2.1 General Cast-in-place segmental bridges shall be designed to be constructed on falsework in accordance with the balanced cantilever method, span-by-span construction, or incremental launching.

8.22.6.2.2 Closure segments The length of a closure segment shall be such as to permit coupling of the duct sheaths and jacking of the tendons in the completed cantilevers.

8.22.6.2.3 Joints The contact surfaces between cast-in-place segments shall be clean, free of laitance, and intentionally roughened. Longitudinal reinforcing bars in the segments shall extend across the joints.

8.22.6.3 Balanced cantilever construction This Clause shall apply to both precast and cast-in-place cantilever construction. Longitudinal tendons may be anchored in the webs, in the slab, or in blisters built out from the web or slab. A minimum of two longitudinal tendons shall be anchored in each segment. Continuity tendons shall be anchored at least one segment beyond the point where they are theoretically required for stresses. The segment lengths, construction loads, and sequence of construction assumed in the design shall be shown on the Plans.

8.22.6.4 Span-by-span construction Provision shall be made in the design of span-by-span construction for accumulated construction force effects due to the change in the structural system as the construction progresses.

8.22.6.5 Incrementally launched construction 8.22.6.5.1 General Tensile stresses under all stages of launching shall not exceed the limits specified in Clause 8.8.4.6(a)(iii)(2). Provision shall be made to resist the frictional forces on the substructure during launching and to restrain the superstructure if the structure is launched down a gradient. For determining the critical frictional forces, the friction on launching bearings shall be assumed to vary between zero and 4%, whichever is critical. The upper value may be reduced to 3.5% if pier deflections and launching jack forces are monitored during construction.

8.22.6.5.2 Force effects due to construction tolerances The force effects due to the permissible construction tolerances specified in Table 8.12 shall be superimposed on those arising from gravity loads.

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Table 8.12 Construction tolerances (See Clause 8.22.6.5.2.) Condition

Tolerance, mm

In the longitudinal direction between bearings of adjacent supports

5

In the transverse direction between two adjacent bearings

3

Between the fabrication area and the launching equipment in the longitudinal and transverse directions

3

Lateral deviation at the outside of the webs

3

The horizontal force acting on the lateral guides of the launching bearings shall be not less than 1/100 of the vertical support reaction. For stresses during construction, one-half of the force effects due to construction tolerances and one-half of the force effects due to temperature as specified in Section 3 shall be superimposed on those arising from gravity loads.

8.22.6.5.3 Design details Piers and superstructure diaphragms at piers shall be designed to permit jacking of the superstructure during all launching stages and for the installation of permanent bearings. Frictional forces during launching shall be considered in the design of the substructure. Local stresses that could develop at the underside of the web during launching shall be investigated. The following dimensional requirements shall be satisfied: (a) launching bearing pads shall not be placed closer than 80 mm to the outside of the web; (b) concrete cover between the soffit and post-tensioning ducts shall not be less than 150 mm; and (c) bearing pressures at the web/soffit corner shall be investigated and the effects of ungrouted ducts and any eccentricity between the intersection of the centrelines of the web and the bottom slab and the centreline of the bearing shall be considered. The straight tendons required to resist forces during launching should be placed in the top and bottom flanges. For T-sections, the bottom tendons shall be located in the lower one-third of the web. The faces of construction joints shall be intentionally roughened or provided with shear keys in accordance with Clause 8.22.6.1.3. The reinforcement in both directions at all concrete surfaces across the joint and extending up to at least 2 m on each side of the joint shall be 15M bars at 200 mm centres.

8.22.7 Precast segmental beam bridges 8.22.7.1 General Precast beam-type segments shall, where practicable, be pretensioned to resist the applicable dead and construction loads so that the tensile stress during construction is limited to 0.6fcr .

8.22.7.2 Joints Joints between the segments shall be epoxied or cast in place. Epoxied joints shall be formed between match-cast surfaces. The match-cast effect in spliced pretensioned girders shall be created by casting against precision-made steel bulkheads. The joints shall meet the requirements of Clause 8.22.6.1.2. Cast-in-place joints shall be wide enough to permit the coupling of duct sheaths and placing of concrete. The strength of concrete in the joints shall be compatible with that of the adjacent girder concrete.

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8.22.7.3 Shear keys Large single-element shear keys shall be provided for match-cast splices. For cast-in-place splices, the ends of the beams at the joints shall be artificially roughened.

8.23 Concrete piles 8.23.1 General The design of concrete piles shall meet the requirements of this Section and Section 6.

8.23.2 Specified concrete strength Unless otherwise Approved, the minimum concrete strength shall be 30 MPa for cast-in-place piles and 35 MPa for precast piles.

8.23.3 Handling Account shall be taken of the handling and transportation of precast piles. An allowance for impact of 50% of the weight of the pile shall be made in proportioning the pile.

8.23.4 Splices The shape and size of a splice shall be such as not to affect the performance of the pile. The strength of a splice shall be at least equal to the strength of the pile in compression, tension, and flexure. The slack in mechanical splices shall be less than 0.5 mm in either compression or tension.

8.23.5 Pile dimensions The minimum diameter or side dimension shall be 200 mm for precast piles and 400 mm for cast-in-place piles. Prestressed concrete piles may be solid or hollow. The minimum wall thickness for hollow piles shall be 125 mm.

8.23.6 Non-prestressed concrete piles 8.23.6.1 General Non-prestressed concrete piles shall meet the requirements of Clauses 8.8.3 and 8.8.5.

8.23.6.2 Reinforcement details 8.23.6.2.1 Cast-in-place The reinforcement details for cast-in-place concrete piles shall meet the requirements of Clauses 8.14 and 8.15.

8.23.6.2.2 Precast For precast concrete piles, the area of longitudinal reinforcement shall not be less than 0.015 and shall not be more than 0.08 of the cross-sectional area of the pile. Longitudinal reinforcement shall be enclosed within spirals that meet the requirements of CSA G30.3. For piles up to 600 mm in diameter, the spiral wire shall have a diameter of at least 5 mm. At the end of a pile, the spiral shall have a pitch of 25 mm for five turns followed by a pitch of 75 mm for 16 turns. For the remainder of the pile, the spiral shall have a pitch of not more than 150 mm. For piles more than 600 mm in diameter, the spiral wire shall have a diameter of at least 6 mm. At the ends of a pile, the spiral shall have a pitch of 40 mm for four turns followed by a pitch of 50 mm for 16 turns. For the remainder of the pile, the spiral shall have a pitch of not more than 100 mm.

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8.23.7 Prestressed concrete piles 8.23.7.1 Effective prestress Prestressing steel shall be placed and stressed to provide an effective prestress of between 3 and 5 MPa for piles up to 12 m long and between 5 and 8 MPa for piles longer than 12 m. The effective axial prestress shall not exceed 0.20fc’.

8.23.7.2 Concrete stress limitations 8.23.7.2.1 Handling Stresses during handling shall not exceed 0.60fc’ in compression and fcr in tension.

8.23.7.2.2 Under loads The stresses at serviceability limit state loads acting on a pile shall be such that (a) no tension develops; and (b) (Ps /Pa + Ms /Ma ) < 1.0 where Pa

= (0.33fc‘ – 0.27fpc)Ag for laterally supported piles = R(0.33fc‘ – 0.27fpc)Ag for laterally unsupported piles with le /r < 120 where R le =

= (1.23 – 0.008le / r ) < 1.0 1.0l for piles hinged at both ends = 0.8 l for piles fixed at one end = 0.6 l for piles fixed at both ends

Ma =

fpc (Ig /c)

8.23.7.3 Factored resistance The basic assumptions of Clause 8.8.3 and the requirements of Clause 8.8.5 shall be used in calculating the resistance of piles.

8.23.7.4 Sections within development length The effect of the transfer length on the stresses at serviceability limit states and the development length on the factored resistance shall be investigated.

8.23.7.5 Reinforcement details The full length of tendons shall be enclosed within spiral wire meeting the requirements of CSA G30.3. Spirals shall be provided in accordance with Clause 8.23.6.2.2.

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Section 9 — Wood structures 9.1 9.2 9.3 9.4 9.4.1 9.4.2 9.4.3 9.4.4 9.5 9.5.1 9.5.2 9.5.3 9.5.4 9.5.5 9.5.6 9.5.7 9.5.8 9.5.9 9.6 9.6.1 9.6.2 9.6.3 9.7 9.7.1 9.7.2 9.7.3 9.7.4 9.7.5 9.8 9.8.1 9.8.2 9.8.3 9.8.4 9.8.5 9.8.6 9.9 9.10 9.11 9.11.1 9.11.2 9.12 9.12.1 9.12.2 9.12.3 9.12.4 9.12.5 9.12.6 9.13 9.13.1 9.13.2 9.14

Scope 384 Definitions 384 Symbols 386 Limit states 388 General 388 Serviceability limit states 388 Ultimate limit states 388 Resistance factor 388 General design 389 Design assumption 389 Spans 389 Load-duration factor 389 Size-effect factors 389 Service condition 389 Load-sharing factor 389 Notched components 390 Butt joint stiffness factor 390 Treatment factor 391 Flexure 391 Flexural resistance 391 Size effect 391 Lateral stability 392 Shear 392 Shear resistance 392 Size effect 393 Shear force and shear load 393 Shear modulus 393 Vertically laminated decks 393 Compression members 393 General 393 Compressive resistance parallel to grain 394 Slenderness effect 394 Amplified moments 396 Rigorous evaluation of amplified moments 396 Approximate evaluation of amplified moments 398 Tension members 399 Compression at an angle to grain 400 Sawn wood 401 Materials 401 Specified strengths and moduli of elasticity 401 Glued-laminated timber 404 Materials 404 Specified strengths and moduli of elasticity 404 Vertically laminated beams 405 Camber 405 Varying depth 405 Curved members 406 Structural composite lumber 406 Materials 406 Specified strengths and moduli of elasticity 406 Wood piles 406

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9.14.1 9.14.2 9.14.3 9.14.4 9.15 9.15.1 9.15.2 9.15.3 9.16 9.17 9.17.1 9.17.2 9.17.3 9.17.4 9.17.5 9.17.6 9.17.7 9.17.8 9.17.9 9.17.10 9.17.11 9.17.12 9.18 9.18.1 9.18.2 9.18.3 9.18.4 9.19 9.19.1 9.19.2 9.19.3 9.19.4 9.19.5 9.20 9.20.1 9.20.2 9.21 9.21.1 9.21.2 9.21.3 9.22 9.22.1 9.22.2 9.22.3 9.22.4 9.22.5 9.23 9.23.1 9.23.2 9.23.3 9.23.4 9.23.5 9.23.6 9.23.7

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Materials 406 Splicing 406 Specified strengths and moduli of elasticity 406 Design 407 Fastenings 407 General 407 Design 408 Construction 408 Hardware and metalwork 408 Durability 408 General 408 Pedestrian contact 408 Incising 408 Fabrication 409 Pressure preservative treatment of laminated veneer lumber 409 Pressure preservative treatment of parallel strand lumber 409 Field treatment 409 Treated round wood piles 409 Untreated round wood piles 409 Pile heads 409 Protective treatment of hardware and metalwork 409 Stress-laminated timber decking 410 Wood cribs 410 General 410 Member sizes and assembly 410 Fastening 410 Load transfer to cribs 410 Wood trestles 411 General 411 Pile bents 411 Framed bents 411 Caps 411 Bracing 411 Stringers and girders 411 Design details 411 Diaphragms 412 Nail-laminated wood decks 412 General 412 Transversely laminated wood decks 412 Longitudinal nail-laminated wood decks 413 Wood-concrete composite decks 413 General 413 Wood base 413 Concrete slab 414 Wood-concrete interface 415 Factored moment resistance 416 Stress-laminated wood decks 417 General 417 Post-tensioning materials 417 Design of post-tensioning system 417 Design of distribution bulkhead 419 Laminated decks 421 Net section 422 Hardware durability 422

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Design details 423 Wearing course 423 Drainage 423 General 423 Deck 424

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Section 9 Wood structures 9.1 Scope This Section applies to structural wood components and their fastenings.

9.2 Definitions The following definitions apply in this Section: Beam and stringer (grading term) — sawn wood with a smaller dimension of at least 114 mm and a larger dimension more than 51 mm greater than the smaller dimension, graded for use in bending with the load applied to the narrow face. Bearing block — a short wood block with its grain parallel to the applied post-tensioning force, used to distribute the forces in a stress-laminated wood bridge with an external post-tensioning system. Butt joint — the discontinuities in a laminated wood deck where the ends of two laminates meet. Crib — a configuration of horizontal members with alternating layers (usually perpendicular to one another) connected to form a closed box. Dimension lumber — sawn wood 38 to 102 mm thick. Direct bearing area — the area of outside lamination over which the post-tensioning is assumed to be applied. Direct bearing pressure — the average pressure that is assumed to be applied to the direct bearing area by the post-tensioning force. Distribution bulkhead — a steel section used to distribute the post-tensioning force. Drift pin — a steel pin used to connect wood members. Duration of load — a period of continuous application of a specified load or the summation of the time periods of intermittent applications of the same load. External post-tensioning system — a system that transversely post-tensions a longitudinally laminated wood deck using two bars at each anchorage, one above and one below the deck. Framed bent — a line of wood columns suitably braced. Glued-laminated timber (Glulam) — structural wood that is manufactured in accordance with CSA O122 and is produced by gluing together a number of laminates with essentially parallel grains. Grade — the designation of the quality of a wood element. Header — a horizontal member of a crib whose longitudinal axis runs perpendicular to the long side of the crib and provides anchorage to the stretchers. Incising — the process of cutting many small slits into the surface of the wood before pressure preservative treatment.

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Internal post-tensioning system — a system for transversely post-tensioning a longitudinally laminated wood deck using a single bar at each anchorage (the bar being situated at the neutral axis of the wood deck). Joist (grading term) — sawn wood that is 38 to 89 mm thick, at least 114 mm wide, and intended to be loaded on its narrow face. Laminate — dimension lumber used in a laminated wood deck or beam. Laminated veneer lumber — structural wood that is manufactured in accordance with ASTM D 5456 and consists of bonded wood veneer sheet elements with their wood fibres primarily oriented along the length of the member. Laminated wood deck — a deck consisting of dimension lumber joined to form a continuous wood slab with the widths oriented vertically. Load-sharing system — a system of members consisting of two or more essentially parallel members arranged or connected in such a way that they mutually support the load and deflect together by approximately the same amount. Longitudinally laminated deck — a laminated wood deck in which the length of the laminates is oriented in the direction of the span of the bridge. Nail-laminated deck — a laminated wood deck joined together only by the successive nailing of each lamination to the preceding one. Parallel strand lumber — structural wood that is manufactured in accordance with ASTM D 5456 and consists of wood strand elements with their wood fibres primarily oriented along the length of the member. Pile bent — a single line of free-standing piles, suitably braced and connected to form a pier. Plank (grading term) — sawn wood that is 38 to 89 mm thick, at least 114 mm wide, and intended to be loaded on its wide face. Post and timber (grading term) — sawn wood with a smaller dimension of at least 114 mm and a larger dimension not more than 51 mm greater than the smaller dimension, graded for use as a column. Preservative treatment — impregnation under pressure with a wood preservative in accordance with the CSA O80 Series of Standards. Sawn wood — wood that is the product of a sawmill and is not further manufactured other than by sawing, resawing, passing lengthwise through a standard planing mill, and crosscutting to length. Specified strength of sawn wood — the assigned strength for calculating resistance, as specified in Tables 9.12 to 9.17. Stress-graded lumber — sawn wood that has been graded in accordance with the NLGA Standard Grading Rules for Canadian Lumber. Stress-laminated wood deck — a laminated wood deck that is post-tensioned perpendicular to the deck laminates using high-strength steel bars. Transversely laminated deck — a laminated wood deck in which the laminates are oriented approximately perpendicular to the direction of the span of the bridge. Wood-concrete composite deck — a longitudinally laminated wood deck made composite with a reinforced concrete overlay.

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Wood mudsill — a horizontal member that bears on soil and is used to distribute vertical loads. Wood preservative — a chemical formulation that is toxic to fungi, insects, borers, and other wood-destroying organisms and meets the requirements of the CSA O80 Series of Standards. Wood trestle — a wood bridge with pile bents or framed bents.

9.3 Symbols The following symbols apply in this Section: A

= cross-sectional area of a member or the bearing area, mm2

Ab

= area of direct bearing on the edge lamination, mm2

Ar

= steel/wood ratio (As /Aw)

As

= total cross-sectional area of post-tensioning steel at one anchorage, mm2

Aw

= product of the distance between two consecutive post-tensioning anchorages and the depth of the wood deck, mm2

b

= width of a member or lamination, mm

bb

= width of the distribution of the post-tensioning forces at the edge lamination, mm

Cc

= slenderness ratio

Ck

= intermediate slenderness factor

Cm

= factor relating the actual moment diagram to an equivalent uniform moment diagram

Cs

= slenderness factor

Db

= diameter of the butt of a pile, mm

De

= width over which elements sharing load deform substantially uniformly, m

Deff

= effective diameter of a pile or other round compression member at 0.45 of the member length above the lower point of contraflexure, mm

Dh

= diameter of a hole for post-tensioning, mm

Dt

= diameter of the tip of a pile, mm

d

= depth of a member or lamination, mm

dc

= depth of a channel bulkhead, mm

Ec

= modulus of elasticity of concrete, MPa

Es

= modulus of elasticity of steel, MPa

E05

= 5th percentile of the modulus of elasticity, MPa

E50

= 50th percentile of the modulus of elasticity, MPa

eb

= unamplified eccentricity at the middle of the unsupported length due to a bow in a column, mm

eo

= unamplified eccentricity at the critical section, mm

fbu

= specified ending b strength, MPa

fpu

= specified compressive strength parallel to grain, MPa; specified tensile strength of a prestressing tendon, MPa

fpy

= specified yield strength of a prestressing tendon, as defined in CSA G279

fql

= limiting pressure perpendicular to the grain, MPa

fqu

= specified compressive strength perpendicular to the grain, MPa

ftg

= specified tensile strength parallel to the grain at the gross section for glued-laminated Douglas fir, MPa

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ftn

= specified tensile strength parallel to the grain at the net section for glued-laminated Douglas fir, MPa

ftu

= specified tensile strength parallel to the grain, MPa

fvu

= specified shear strength for a 1.0 m3 cube subjected to uniform shear, MPa

I

= moment of inertia of a section, mm4

Ib

= moment of inertia of a pile at its butt, mm4

k

= effective length factor

kb

= modification factor for the effect of butt joints on the stiffness of laminated wood decks

kc

= slenderness factor

kd

= modification factor for duration of load

kl s

= modification factor for lateral stability

km

= modification factor for load sharing

ksb

= modification factor for the size effect for flexure

ksp

= modification factor for the size effect for compression parallel to the grain

ksq

= modification factor for the size effect for compression perpendicular to the grain

kst

= modification factor for the size effect for tension

ksv

= modification factor for the size effect for shear

ku

= ratio of effective length to total length of a pile

L

= length of a component, mm

Lb

= length of the distribution of the post-tensioning force along the edge lamination, mm

Lp

= length of a steel anchorage plate, mm

Lu

= laterally unsupported length of a component, mm

Mc

= amplified moment used for proportioning slender compression members, N•mm

Mp

= factored unamplified moment at the critical section of a pile, N•mm

Mr

= factored resistance of a member in flexure, N•mm

Mx

= amplified moment about the x-axis of a compression member, N•mm

Mxr

= factored resistance in bending about the x-axis of a compression member, N•mm

My

= amplified moment about the y-axis of a compression member, N•mm

Myr

= factored resistance in bending about the y-axis of a compression member, N•mm

M0

= total factored maximum unamplified moment for columns other than tapered piles, N•mm

M1

= value of the smaller end moment at the ultimate limit state due to factored loads acting on a compression member (positive if the member is bent in single curvature and negative if bent in double curvature), N•mm

M2

= value of the larger end moment at the ultimate limit state due to factored loads acting on a compression member (always positive), N•mm

Nb

= a measure of the frequency of butt joints in laminated wood decks, being, for any 1.0 m wide band perpendicular to the laminates, the minimum number of laminates without joints adjacent to a laminate having a butt joint

Nf

= assumed uniformly distributed normal pressure after losses, MPa

Nj

= assumed uniformly distributed normal pressure at transfer, MPa

P

= factored axial load, N

Pcr

= factored Euler buckling load, N

Pr

= factored resistance in compression of an axially loaded short column, N

Rr

= factored resistance in bearing, N

S

= section modulus, mm3

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Sb

= section modulus of a transformed section of a composite wood-concrete deck with respect to the bottom fibres, mm3

St

= section modulus of a transformed section of a composite wood-concrete deck with respect to the reinforcing steel, mm3

s

= spacing of prestressing anchorages, m

T

= total time for which a segment of a transversely laminated deck is not under stress

Tr

= factored resistance in tension, N

tp

= thickness of an anchorage plate, mm

V

= volume of a beam, m3

Vf

= factored shear load on a member, kN

Vr

= factored shear resistance, N

w

= width of a steel anchorage plate, mm

δ η θ φ φs

= moment amplification factor = factor used in computing Pcr for tapered piles = angle between the plane of loading and the direction of the grain, degrees = resistance factor for wood components = resistance factor for steel components

9.4 Limit states 9.4.1 General Structural components shall be proportioned to satisfy the requirements at the serviceability limit state in accordance with Clause 9.4.2 and at the ultimate limit state in accordance with Clause 9.4.3.

9.4.2 Serviceability limit states The superstructure vibration limitation specified in Clause 3.4.4 and the deflection limitations at serviceability limit states specified in this Clause shall apply to wood components. The deflection of a component shall not exceed 1/400 of the span of the component and shall be calculated using E50 obtained from Tables 9.12 to 9.17. Only live load shall be considered in accordance with SLS Combination 1 of Table 3.1, excluding dynamic load allowance, and the truck shall be placed as specified in Clause 3.8.4.1.

9.4.3 Ultimate limit states Components shall be proportioned to have a factored resistance not less than the sum of the load effects due to the factored loads specified in Section 3.

9.4.4 Resistance factor

The resistance factor for wood components, φ , shall be as specified in Table 9.1.

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Table 9.1 Resistance factor for wood components, φ (See Clauses 9.4.4, 9.22.5.2, and 9.23.4.2.) Load effect

Component type

Flexure

Shear

Compression parallel to grain

Sawn wood Glued-laminated timber Structural composite lumber Piles

0.9 0.9 0.9 0.9

0.9 0.9 0.9 0.9

0.8 0.8 0.8 0.8

Compression perpendicular to grain

Tension parallel to grain

0.8 0.8 0.8 0.8

0.9 0.9 0.9 0.9

9.5 General design 9.5.1 Design assumption In accordance with Section 5, only linear elastic analysis shall be used.

9.5.2 Spans The span length of simply-supported components shall be taken as the distance face-to-face of supports plus one-half the required length of bearing at each end. For continuous members, the span shall be taken as the distance between centres of supports.

9.5.3 Load-duration factor The value of factor kd shall be taken as 0.7 when considering dead load alone, earth pressure alone, and dead load plus earth pressure only. For load combinations including wind and earthquake, the factor shall be taken as 1.15. For all other cases, kd shall be taken as 1.0.

9.5.4 Size-effect factors The values of size-effect factors shall be obtained from the following clauses: (a) ksb : Clause 9.6.2; (b) ksv : Clause 9.7.2; (c) ksp : Clauses 9.8.2.2 and 9.8.2.3; (d) ksq : Clause 9.10; and (e) kst : Clause 9.9.

9.5.5 Service condition It shall be assumed that the properties specified in Tables 9.12 to 9.17 have been modified for the appropriate service condition.

9.5.6 Load-sharing factor For systems of members in flexure and shear, and for tension members at the net section, the load-sharing factor, km , shall be obtained either directly or by linear interpolation from Table 9.2 for the number of load-sharing components, n. For members in compression not spaced more than 600 mm apart, km shall be taken as 1.1. For all other systems, km shall be taken as 1.0. For moments and shears in flexural members, n shall not be greater than the number of components within the widths De and 0.8De , respectively, where De is as specified in Table 9.3.

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Table 9.2 Load-sharing factor for bending, shear, and tension for all species and grades (See Clause 9.5.6.) Number of load-sharing components, n

Load-sharing factor, km

2

1.10

3

1.20

4

1.25

5

1.25

6

1.30

10

1.35

15

1.40

20

1.40

Table 9.3 Values of De (See Clause 9.5.6.) Structure

De , m

Longitudinal nail-laminated deck

0.85

Transverse nail-laminated deck

0.40

Longitudinal stress-laminated deck

1.75

Transverse stress-laminated deck

0.75

Stringer of sawn timber stringer bridge

1.75

Longitudinal laminate of wood-concrete composite deck

1.60

9.5.7 Notched components Notches or abrupt changes in section shall not be used unless a detailed assessment of the stress concentration effect has been made.

9.5.8 Butt joint stiffness factor The stiffness of laminated wood decks shall be adjusted by a modification factor, kb , to account for the effect of butt joints. For decks other than longitudinal nail-laminated decks, kb shall be calculated as follows: kb = (Nb – 1)/Nb

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where the frequency of butt joints is 1 in Nb , as specified in Clauses 9.21.2.2.5 and 9.22.2.2.2. For longitudinal nail-laminated wood decks other than wood-concrete composite decks, the value of kb shall be calculated as follows: kb = 0.8(Nb – 1)/Nb

9.5.9 Treatment factor The properties specified given in this Section incorporate adjustments for preservative treatment and incising. For wood treated with a fire retardant or other strength-reducing chemicals, the assumed properties shall be based on the documented results of tests that take into account the effects of time, temperature, and moisture content.

9.6 Flexure 

9.6.1 Flexural resistance The factored resistance, Mr , of glued-laminated members shall be the lesser of Mr =  kd ks km fbu S and Mr =  kd km ksb fbu S The factored resistance, Mr , shall be calculated as follows for all other wood members: Mr =  kd ks km ksb fbu S where fbu is obtained from Tables 9.12 to 9.17, as applicable, and the values of kd , ks , km , and ksb are specified in Clauses 9.5.3, 9.6.3, 9.5.6, and 9.6.2, respectively.



9.6.2 Size effect The value of ksb for glued-laminated members shall be calculated as follows: ksb = 1.03 (b × L × 10–6)–0.18 where b is the beam width (for single-piece laminations) or the width of the widest piece (for multiple-piece laminations) and L is the length of beam segment from point of zero moment to point of zero moment. The value of ksb for sawn wood members shall be obtained from Table 9.4. The value of ksb for members other than glued-laminated or sawn wood members shall be 1.0.

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Table 9.4 Size-effect factors ksb for flexure and k sv for shear for all species and grades (See Clauses 9.6.2, 9.7.2, and 9.22.5.2.) Larger dimension, mm Smaller dimension, mm

89

140

184

235

286

337

387

64 > 64 but < 114 114

1.7 1.7 —

1.4 1.5 1.3

1.2 1.3 1.3

1.1 1.2 1.2

1.0 1.1 1.1

0.9 1.0 1.0

0.8 0.9 0.9

9.6.3 Lateral stability The value of ks shall be obtained from Table 9.5, where b and d are, respectively, the width and depth of the beam or laminate, and Cs and Ck are calculated as follows:

Cs =

Lud b2

Ck =

E 05 fbu

where Lu is the laterally unsupported length of the component and fbu and E05 are obtained from Tables 9.12 to 9.17, as applicable. For laminated wood decks, or when the compression edge of a beam is effectively supported along its length, ks shall be taken as 1.0. When d/ b is greater than 1.0, lateral support shall be provided at points of bearing to restrain torsional rotation. A beam shall not have Cs greater than 30.0.

Table 9.5 Modification factor for lateral stability, ks (See Clause 9.6.3.)

d/b

Cs

ks

 1.0 > 1.0 > 1.0 > 1.0

— 10.0 > 10.0 but < Ck Ck

1.0 1.0 1 – 0.3(Cs /Ck)4 (0.70E05) / (Cs2fbu)

9.7 Shear 9.7.1 Shear resistance The factored shear resistance, Vr , of a member of rectangular section shall be calculated as follows: Vr =  kd km ksv fvu A/1.5 where fvu is obtained from Tables 9.12 to 9.17 and the values of kd , km , and ksv are as specified in Clauses 9.5.3, 9.5.6, and 9.7.2, respectively.

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9.7.2 Size effect The value of factor ksv for sawn wood members shall be obtained from Table 9.4. The value of ksv for glued-laminated timbers shall be V –0.18.

9.7.3 Shear force and shear load The factored shear resistance of a sawn member shall equal or exceed the factored shear force acting on the member (the shear effects of all loads acting within a distance from a support equal to the depth of the member need not be considered). The factored shear resistance of a glued-laminated member shall equal or exceed the factored shear load on the member, Vf , calculated as follows: 5 ⎡1 L ⎤ Vf = 0.82 ⎢ ∫ V ( x ) dx ⎥ ⎣L 0 ⎦

0.2

where |V(x)| = absolute value of the total factored shear force at a section at distance x along the length of the member

9.7.4 Shear modulus The value of the shear modulus shall be 0.065 times the modulus of elasticity, E50 , obtained from Tables 9.14 to 9.17.

9.7.5 Vertically laminated decks Shear shall be neglected in vertically laminated decks.

9.8 Compression members 

9.8.1 General The proportioning of compression members shall satisfy the following: 2

⎛P⎞ Mc ⎜⎝ P ⎟⎠ + M ≤ 1.0 (for uniaxial bending) r r P M x My + + ≤ 1.0 (for biaxial bending) Pr Mxr Myr where (a) the factored resistance in compression, Pr , is as specified in Clause 9.8.2.1; (b) the factored resistance in flexure, Mr , is as specified in Clause 9.6.1; (c) the factored resistances in flexure, Mxr and Myr , for bending about the x- and y-axes, respectively, are calculated in the same manner as Mr ; (d) the amplified moment, Mc , is calculated in accordance with Clause 9.8.5.1 or 9.8.6 by taking into account the slenderness effects specified in Clause 9.8.3; and (e) the amplified moments, Mx and My , acting about the x- and y- axes, respectively, are calculated in the same manner as Mc .

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9.8.2 Compressive resistance parallel to grain 9.8.2.1 General The factored compressive resistance parallel to the grain, Pr , shall be calculated as follows: Pr =  km kd ksp kc fpu A where ksp is obtained from Clause 9.8.2.2 or 9.8.2.3, kc is obtained from Clause 9.8.2.4, and fpu is obtained from Tables 9.9 to 9.13.

9.8.2.2 Size factor for sawn wood in compression The size factor, ksp , for sawn wood in compression parallel to the grain shall be calculated as follows: ksp = 6.3(dL)–0.13  1.3 where d

= dimension in the direction of buckling, mm

L

= unsupported length associated with the member dimension, mm

9.8.2.3 Size factor for glued-laminated timber in compression The size factor, ksp , for glued-laminated timber in compression parallel to the grain shall be calculated as follows: ksp = 0.68V –0.13  1.3

9.8.2.4 Slenderness factor The slenderness factor, kc , for members in compression parallel to the grain shall be calculated as follows:

⎡ kmkd kspfpuCc3 ⎤ kc = ⎢1+ ⎥ 35E 05 ⎢⎣ ⎥⎦

−1.0

where Cc is determined in accordance with Clause 9.8.3.3 and E05 is obtained from Tables 9.12 to 9.17.

9.8.3 Slenderness effect 9.8.3.1 Effective length The effective length of a compression member shall be taken as kLu and, for members other than piles, the following requirements shall apply: (a) the unsupported length, Lu , shall be taken as the centre-to-centre distance of lateral supports capable of sustaining a lateral restraint force of at least 0.04P, together with any other force that is generated by the effects of end moments and lateral loading; (b) for compression members braced against side-sway, the effective length factor, k, shall be taken as 1.0 unless rigorous analysis confirms a lower value; and (c) for compression members not braced against side-sway, the effective length factor, k, corresponding to the end-restraint condition of the member, shall be obtained from Table 9.6 or shall be determined by rigorous analysis. For the latter case, the value of k shall not be taken as less than 1.0.

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Table 9.6 Minimum values of the effective length factor, k (See Clauses 9.8.3.1 and 9.8.3.2.)

End restraint

Minimum value of effective length factor, k

Held in position and restrained against rotation at both ends

0.65

Held in position at both ends and restrained against rotation at one end

0.80

Held in position but free to rotate at both ends

1.00

Held in position and restrained against rotation at one end, and restrained against rotation, but not held in position, at the other end

1.20

Held in position and restrained against rotation at one end, and partially restrained against rotation, but not held in position, at the other end

1.50

Held in position at one end, but not restrained against rotation, and restrained against rotation, but not held in position, at the other end

2.00

Held in position and restrained against rotation at one end, but not held in position or restrained against rotation at the other end

2.00

9.8.3.2 Effective length of piles When the finished pile projects above the ground and is not braced against buckling, the effective length shall be determined in accordance with Table 9.6 (using the value associated with the end restraint provided by the structure the pile supports) and in accordance with the following requirements: (a) in firm ground, the lower point of contraflexure of the pile shall be taken at a depth below the ground level that is not greater than one-tenth of the exposed length of the pile; (b) where the top stratum of the ground is soft clay or silt, the lower point of contraflexure of the pile shall be taken at a depth below the ground level that is not greater than one-half of the depth of penetration into this stratum or less than one-tenth of the exposed length of the pile; and (c) a stratum of extremely soft soil, peat, or mud shall be treated as if it were water. Where a pile is wholly embedded in soil, the effect of slenderness may be ignored.

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

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9.8.3.3 Slenderness ratio For simple compression members of constant rectangular section, the slenderness ratio, Cc , shall not exceed 50 and shall be taken as

Cc =

effective length, kLu , associated with width h member width

and

Cc =

effective length, kLu , associated with depth h member depth

For sawn wood members, compression capacity shall be calculated separately for member width and member depth using the corresponding slenderness ratio. For glued-laminated members, the greater slenderness ratio may be used to calculating compression capacity. For piles and other round compression members, the slenderness ratio, Cc , shall not exceed 50 and shall be calculated as follows: Cc = kLu /0.866Deff

9.8.4 Amplified moments At the ultimate limit state, the effect of lateral deflection in causing or amplifying bending due to axial loads shall be considered as follows: (a) for members not braced against side-sway, when Cc is greater than 11.6; and (b) for members braced against side-sway, when Cc is greater than 17.3 – 5.8M1/M2.

9.8.5 Rigorous evaluation of amplified moments 9.8.5.1 General When the approximate method of Clause 9.8.6 is not adopted, the amplified moment, Mc , shall be obtained by taking account of the effect of factored axial loads in amplifying the moments due to end eccentricities, bow, and lateral loads in the unsupported length, Lu . The unsupported length shall be determined in accordance with Clause 9.8.3.1 or 9.8.3.2, the end eccentricity in accordance with Clause 9.8.5.2 or 9.8.5.3, and the bow moments in accordance with Clause 9.8.5.4.

9.8.5.2 End eccentricity All compression members, except piles, shall be analyzed for end eccentricity at each end. The eccentricity shall be taken as the greater of (a) the eccentricity corresponding to the maximum end moment associated with the axial load; and (b) 0.05 times the lateral dimension of the member in the plane of the flexure being considered. The eccentricity corresponding to Item (b) shall be assumed to cause uniaxial bending with single curvature.

9.8.5.3 End eccentricity in piles When lateral displacement of the pile butt is prevented, the moment, Mp , shall be determined at a section 0.55 times the effective length below the butt, and shall be calculated as the product of P and eo , plus the effects of end moments and the moments due to lateral loads. The value of eo shall be obtained from Table 9.7.

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Table 9.7 A, S, and eo* for piles at 0.55 of the effective length below the butt joint (See Clause 9.8.5.3.) ku Db , mm

Dt , mm

Property

0.3

0.4

0.5

0.6

0.7

356

254

A S eo

9.03 3.82 29

8.71 3.62 36

8.45 3.44 47

8.13 3.28 62

7.81 3.10 79

229

A S eo

8.77 3.67 29

8.45 3.44 35

8.06 3.23 46

7.68 3.02 60

7.35 2.85 77

203

A S eo

8.58 3.54 28

8.13 3.28 35

7.68 3.02 44

7.29 2.79 58

6.90 2.56 74

254

A S eo

7.94 3.15 28

7.68 3.02 35

7.48 2.90 45

7.29 2.79 59

7.10 2.67 76

229

A S eo

7.68 3.02 28

7.42 2.85 34

7.16 2.70 44

6.90 2.56 57

6.65 2.41 73

203

A S eo

7.48 2.90 27

7.16 2.70 33

6.84 2.52 42

6.52 2.34 55

6.19 2.18 70

178

A S eo

7.29 2.79 27

6.90 2.56 32

6.52 2.34 41

6.13 2.15 53

5.74 1.95 67

229

A S eo

6.71 2.44 27

6.52 2.34 33

6.32 2.25 42

6.13 2.15 54

5.94 2.05 70

203

A S eo

6.52 2.34 26

6.26 2.21 32

6.00 2.08 41

5.74 1.95 52

5.48 1.84 67

178

A S eo

6.32 2.25 26

6.00 2.08 31

5.68 1.92 39

5.42 1.77 50

5.16 1.64 64

203

A S eo

5.61 1.87 26

5.42 1.79 31

5.23 1.69 39

5.10 1.61 50

4.90 1.52 64

178

A S eo

5.42 1.77 25

5.16 1.67 30

4.97 1.56 37

4.71 1.46 48

4.52 1.36 61

152

A S eo

5.24 1.69 25

4.95 1.56 29

4.67 1.43 36

4.41 1.31 46

4.16 1.20 58

254

152

A S eo

4.41 1.31 24

4.21 1.22 28

3.99 1.13 34

3.81 1.05 43

3.61 0.97 55

229

152

A S eo

3.61 0.99 23

3.52 0.93 27

3.37 0.87 33

3.25 0.82 41

3.11 0.77 52

330

305

279

*A is in mm2 × 104, S is in mm3 × 106, and eo is in mm. November 2006

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9.8.5.4 Bow moments All compression members, except piles, shall be analyzed for bow moments midway between the points of lateral support due to an eccentricity, eb , equal to Lu /500. Bow moments shall be assumed to act in the same plane and with the same sense as the end moments derived from Clause 9.8.5.2.

9.8.6 Approximate evaluation of amplified moments In the absence of a rigorous analysis, the amplified moments shall be obtained as follows: (a) Compression members, except piles, shall be designed using the factored axial load at the ultimate limit state and a magnified moment, Mc , calculated as follows: Mc = δ M0 (but not less than M2) where

d

=

Cm 1 .0 −

P fPcr

where

= kd km

Pcr

π2E 05I kL2u

and kd and km are obtained from Clauses 9.5.3 and 9.5.6, respectively. (b) For members braced against side-sway and without lateral loads between supports, Cm shall be calculated as follows:

Cm = 0.6 + 0.4

M1 ≥ 0.4 M2

(c) For all cases not covered by Item (b), Cm shall be 1.0. (d) For piles, the method specified in Item (a) shall be used, except that Mc shall be calculated as follows: Mc = δ Mp (but not less than M2) where

d

=

Cm 1 .0 −

P fPcr

where

Pcr

= kd

hE 05Ib

(kLu )2

and η is obtained from Table 9.8.

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Table 9.8 η to be used in calculating Pcr for piles (See Clause 9.8.6.) η for ku equal to Db , mm*

Dt , mm*

0.3

0.4

0.5

0.6

0.7

356

254 229 203

8.25 7.87 7.49

7.74 7.25 6.78

7.25 6.66 6.09

6.77 6.09 5.45

6.31 5.55 4.79

330

254 229 203 178

8.55 8.13 7.72 7.33

8.13 7.59 7.07 6.56

7.72 7.07 6.44 5.84

7.33 6.56 5.84 5.18

6.94 6.08 5.27 4.52

305

229 203 178

8.44 8.00 7.56

7.99 7.41 6.85

7.55 6.85 6.18

7.13 6.31 5.55

6.71 5.80 4.95

279

203 178 152

8.33 7.84 7.36

7.84 7.21 6.61

7.37 6.61 5.89

6.91 6.03 5.22

6.47 5.49 4.59

254

152

7.64

6.96

6.82

5.70

5.12

229

152

7.99

7.41

6.85

6.82

5.80

*Within ± 5 mm.

9.9 Tension members The factored resistance of a tension member, Tr , shall be calculated as follows: Tr = φ kd km kst ftu A where kd is as specified in Clause 9.5.3, kst applies only to dimension lumber at the net section and is obtained from Table 9.9 for all species and grades, andkm applies only at the net section and is as specified in Clause 9.5.6. For all other cases, kst and km shall be taken as 1.0.

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Table 9.9 Size-effect factor, kst , for tension at net section in dimension lumber (See Clause 9.9.) Depth, mm

Factor*

89

1.50

114

1.40

140

1.30

184

1.20

235

1.10

286

1.00

337

0.90

387 and larger

0.80

*Linear interpolation is permitted.

9.10 Compression at an angle to grain The factored resistance in bearing, Rr , for loads applied at an angle θ to the grain shall be calculated as follows:

Rr = f ksq kd

Afpufqu 2

fpu sin f + fqu cos2 f

where φ is 0.8, fpu and fqu are obtained from Tables 9.12 to 9.16, and kd is as specified in Clause 9.5.3. When the larger dimension or the diameter of the bearing area is less than 150 mm, no part of the bearing area is closer than 75 mm to the end of the member, and the bending moments at the bearing section do not exceed 0.4Mr , ksq shall be obtained from Table 9.10. For all other cases, ksq shall be taken as 1.0.

Table 9.10 Size-effect factor for bearing, ksq (See Clause 9.10.) Length of bearing, mm

Factor*

15

1.75

25

1.38

40

1.25

50

1.19

75

1.13

100

1.10

150 or more

1.00

*Linear interpolation is permitted.

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November 2006

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Canadian Highway Bridge Design Code

9.11 Sawn wood 9.11.1 Materials 9.11.1.1 Species and species combinations Only the individual species and species combinations specified in Table 9.11 shall be used.

Table 9.11 Permitted species and species combinations for sawn wood (See Clause 9.11.1.1.)

Species combinations

Treatable species included in species combination

Stamp identification

Douglas fir–Larch

Douglas fir

D.FIR-L(N)

Hem-Fir

Western hemlock* Amabilis fir

W.Hem(N) Am Fir(N)

Spruce-Pine-Fir

Lodgepole pine* Jack pine

L Pine(N) J Pine(N)

Northern species

Ponderosa pine Red pine Western red cedar

P Pine R Pine WR Cedar(N)

*Treatable with some difficulty.

9.11.1.2 Grades of sawn wood All wood shall be stress-graded in conformity with the NLGA Standard Grading Rules for Canadian Lumber and shall comply with CSA O141.

9.11.1.3 Identification of wood All wood shall be identified by a grade stamp or certification of an association or independent grading agency approved by the Canadian Lumber Standards Accreditation Board as specified in CSA O141. When it is possible that preservative treatment could obscure the grade stamp, a certificate of inspection or other Approved evidence of grade shall be supplied by the treating company.

9.11.2 Specified strengths and moduli of elasticity The specified strengths and moduli of elasticity for structural joists and planks shall be obtained from Table 9.12, for beam and stringer grades from Table 9.13, and for post and timber grades from Table 9.14.

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Table 9.12 Specified strengths and moduli of elasticity for structural joists and planks, MPa (See Clauses 9.5.5, 9.6.3, 9.8.2.1, 9.8.2.4, 9.10, 9.11.2, 9.22.5.1, 9.22.5.2, and 14.14.1.7.3.)

Species combination

Grade

Bending Compression at extreme Longitudinal parallel to shear, fvu fibre, fbu grain, fpu

Tension Compression parallel perpendicular to grain, to grain, fqu ftu

Modulus of elasticity E50

E05

Douglas fir–Larch

SS No.1/ No.2

11.8 7.1

1.6 1.6

11.1 8.2

4.0 4.0

7.6 4.1

11 200 9 800

7 600 6 300

Hem-Fir

SS No.1/ No.2

11.4 7.9

1.3 1.3

10.3 8.7

2.6 2.6

6.9 4.4

10 700 9 800

7 600 6 700

SprucePine-Fir

SS No.1/ No.2

11.8 8.4

1.2 1.2

8.5 6.7

3.0 3.0

6.1 3.9

9 400 8 500

6 700 5 800

Northern species

SS No.1/ No.2

7.6 5.4

1.1 1.1

7.6 6.1

2.0 2.0

4.4 2.9

6 700 6 300

4 900 4 500

Note: These values are based on CAN/CSA-O86 ultimate strengths and the following conditions: (a) maximum dimension of 286 mm; (b) least dimension of 89 mm or less; (c) wet service conditions; (d) standard term duration of load; and (e) preservative treated and incised.

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Canadian Highway Bridge Design Code

Table 9.13 Specified strengths and moduli of elasticity for beam and stringer grades, MPa (See Clauses 9.5.5, 9.6.3, 9.8.2.1, 9.8.2.4, 9.10, 9.11.2, 9.23.4.4.6, 14.14.1.7.3, 16.12.2.1, 16.12.2.2, 16.12.3.1, and 16.12.3.2.) Tension Compression parallel perpendicular to grain, to grain, fqu ftu

Modulus of elasticity

Grade

Bending Compression at extreme Longitudinal parallel to fibre, fbu shear, fvu grain, fpu

E50

E05

Douglas fir–Larch

SS No.1 No.2

19.5 15.8 9.0

1.5 1.5 1.5

12.0 10.0 6.6

4.7 4.7 4.7

10.0 7.0 3.3

12 000 12 000 9 500

8 000 8 000 6 000

Hem-Fir

SS No.1 No.2

14.5 11.7 6.7

1.2 1.2 1.2

9.8 8.2 5.4

3.1 3.1 3.1

7.4 5.2 2.4

10 000 10 000 8 000

7 000 7 000 5 500

SprucePine-Fir

SS No.1 No.2

13.6 11.0 6.3

1.2 1.2 1.2

8.6 7.2 4.7

3.6 3.6 3.6

7.0 4.9 2.3

8 500 8 500 6 500

6 000 6 000 4 500

Northern species

SS No.1 No.2

12.8 10.8 5.9

1.0 1.0 1.0

6.6 5.5 3.5

2.3 2.3 2.3

6.5 4.6 2.2

8 000 8 000 6 000

5 500 5 500 4 000

Species combination

Notes: (1) Beam and stringer grades have a smaller dimension of at least 114 mm and a larger dimension more than 51 mm greater than the smaller dimension. (2) An approximate value for the modulus of rigidity may be estimated as 0.065 times the modulus of elasticity. (3) With sawn members that are thicker than 89 mm and season slowly, care shall be taken to avoid overloading in compression before appreciable seasoning of the outer fibre has taken place. Alternatively, compression strengths for wet service conditions shall be used. (4) The beam and stringer grades specified in this Table are not graded for continuity. (5) The values in this Table are based on CAN/CSA-O86 ultimate strengths and the following conditions: (a) 343 mm larger dimension for bending and shear and 292 mm larger dimension for tension and compression parallel to grain; (b) wet service conditions; and (c) standard term duration of load. (6) The specified strengths for beam and stringer grades are based on loads applied to the narrow face of the member. When beam and stringer grade members are subjected to loads applied to the wide face, the specified strength for bending at the extreme fibre and the specified modulus of elasticity shall be multiplied by the following factors: Grade

Factor for fbu

Factor for E50 or E05

SS

0.88

1

No. 1/No. 2

0.77

0.9

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Table 9.14 Specified strengths and moduli of elasticity for post and timber grades, MPa (See Clauses 9.5.5, 9.6.1, 9.6.3, 9.7.1, 9.7.4, 9.8.2.1, 9.8.2.4, 9.10, 9.11.2, 9.23.4.4.6, and 14.14.1.7.3.) Tension Compression parallel perpendicular to grain, to grain, fqu ftu

Modulus of elasticity

Grade

Bending Compression at extreme Longitudinal parallel to shear, fvu fibre, fbu grain, fpu

E50

E05

Douglas fir–Larch

SS No.1 No.2

18.3 13.8 6.0

1.5 1.5 1.5

12.6 11.1 6.8

4.7 4.7 4.7

10.7 8.1 3.8

12 000 10 500 9 500

8 000 6 500 6 000

Hem-Fir

SS No.1 No.2

13.6 10.2 4.5

1.2 1.2 1.2

10.3 9.1 5.6

3.1 3.1 3.1

7.9 6.0 2.8

10 000 9 000 8 000

7 000 6 000 5 500

SprucePine-Fir

SS No.1 No.2

12.7 9.6 4.2

1.2 1.2 1.2

9.0 7.9 4.9

3.6 3.6 3.6

7.4 5.6 2.6

8 500 7 500 6 500

6 000 5 000 4 500

Northern species

SS No.1 No.2

12.0 9.0 3.9

1.0 1.0 1.0

6.8 6.1 3.7

2.3 2.3 2.3

7.0 5.3 2.5

8 000 7 000 6 000

5 500 5 000 4 000

Species combination

Notes: (1) Post and timber grades have a smaller dimension of at least 114 mm and a larger dimension not more than 51 mm greater than the smaller dimension. (2) Post and timber grades graded according to the rules for beam and stringer grades may be assigned beam and stringer strength. (3) An approximate value for the modulus of rigidity may be estimated as 0.065 times the modulus of elasticity. (4) With sawn members that are thicker than 89 mm and season slowly, care should be exercised to avoid overloading in compression before appreciable seasoning of the outer fibres has taken place. (5) The values in this Table are based on CAN/CSA-O86 ultimate strengths and the following conditions: (a) 343 mm larger dimension for bending and shear and 292 mm larger dimension for tension and compression parallel to grain; (b) wet service conditions; and (c) standard term duration of load.

9.12 Glued-laminated timber 9.12.1 Materials All structural glued-laminated timber shall be manufactured in accordance with CSA O122 by a plant certified in accordance with CSA O177.

9.12.2 Specified strengths and moduli of elasticity The specified strengths and moduli of elasticity for glued-laminated Douglas fir timber shall be obtained from Table 9.15.

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Table 9.15 Specified strengths and moduli of elasticity for glued-laminated Douglas fir timber, MPa



(See Clauses 9.5.5, 9.6.1, 9.6.3, 9.7.1, 9.7.4, 9.8.2.1, 9.8.2.4, 9.10, and 9.12.2.) CSA stress grade 24f-E bending grade

24f-EX bending grade

Bending moment positive, fbu

27.5

27.5

23

23

12.6

21.9

Bending moment negative, fbu

12.6

27.5

12.6

23

12.6

21.9

1.4

1.4

1.4

1.4

1.4

1.4

Compression parallel to grain, fpu

26.4*

26.4*

26.4*

26.4*

26.4

26.4

Compression parallel to grain combined with bending, fpu

26.4*

26.4

26.4*

26.4

26.4

26.4

5.8

5.8

5.8

5.8

5.8

5.8

Axial tension at gross section, ftg

13.4*

13.4

13.4*

13.4

13.4

15.7

Axial tension at net section, ftn

17.9*

17.9

17.9*

17.9

17.9

20.1

Type of stress

Longitudinal shear, fvu

Compression perpendicular to grain, fqu

Modulus of elasticity E50 E05

12 100 10 600

12 100 10 600

20f-E bending grade

11 800 10 200

20f-EX bending grade

11 800 10 200

16c-E compression grade

11 800 10 200

18t-E tension grade

13 100 11 400

*The use of this stress grade for this primary application is not recommended. Notes: (1) Designers should check the availability of grades before specifying. (2) The values in this Table are based on the following standard conditions: (a) semi-wet service conditions; and (b) standard term duration of load.

9.12.3 Vertically laminated beams The factored resistance in flexure for beams composed of vertical laminations shall be calculated as for load-sharing systems in sawn wood.

9.12.4 Camber Glued-laminated beams shall be cambered by the sum of 1/600 of the span plus twice the calculated deflection due to the unfactored dead loads.

9.12.5 Varying depth When there is a variation in the depth of a flexural member, the bevel of the laminates on the tension side shall not be steeper than 7% and the factored fibre stress shall not be less than 50% of the specified strength. May 2010 (Replaces p. 405, November 2006)

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9.12.6 Curved members The requirements of this Section shall apply only to glued-laminated members with a radius greater than 12 m. In such members the reduction in capacity due to curvature may be ignored.

9.13 Structural composite lumber 9.13.1 Materials Structural composite lumber shall be laminated veneer lumber or parallel strand lumber manufactured from Douglas fir.

9.13.2 Specified strengths and moduli of elasticity The specified strengths and moduli of elasticity shall be obtained from ASTM D 5456, as modified by the procedures specified in CAN/CSA-O86. Typical values for some representative products are specified in Table 9.16.

Table 9.16 Typical specified strengths and moduli of elasticity for structural composite lumber, MPa (See Clauses 9.5.5, 9.6.1, 9.6.3, 9.7.1, 9.7.4, 9.8.2.1, 9.8.2.4, and 9.10.) Laminated veneer lumber Type of stress Bending at extreme fibre, fbu Longitudinal shear — Parallel, fvu* Longitudinal shear — Perpendicular, fvu* Compression parallel to grain, fpu Compression perpendicular to grain — Parallel, fqu* Compression perpendicular to grain — Perpendicular, fqu* Axial tension parallel to grain, ftu Modulus of elasticity E50 E05

32.1 3.3 2.0 31.2 8.6 5.5 20.0 13 000 11 300

Parallel strand lumber 33.2 3.3 2.4 33.2 8.6 5.5 27.5 13 000 11 300

*To glueline for laminated veneer lumber and to wide face of strand for parallel strand lumber. Note: These values are provided for illustrative purposes; the design values shall be obtained after verification of the structural properties and adjustment factors of the proprietary products.

9.14 Wood piles 9.14.1 Materials Wood pile materials shall comply with CSA CAN3-O56.

9.14.2 Splicing Splicing of wood piles shall require Approval.

9.14.3 Specified strengths and moduli of elasticity The specified strengths and moduli of elasticity for round wood piles shall be obtained from Table 9.17.

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Table 9.17 Specified strengths and moduli of elasticity for round wood piles, MPa (See Clauses 9.5.5, 9.6.1, 9.14.3, 9.14.4.2, 9.14.4.3, and 16.9.6.8.)

Bending at extreme fibre, fbu

Douglas fir and western larch

Longitudinal shear, fvu

Compression Compression parallel to perpendicular grain, fpu to grain, fqu

Tension parallel to grain, ftu

20.1

1.4

17.0

5.2

Jack pine

18.1

1.5

14.2

Lodgepole and ponderosa pine

14.2

1.0

Red pine

13.6

1.2

Species

Modulus of elasticity E50

E05

13.6

11 000

7 000

3.5

11.6

7 000

5 000

12.0

3.5

9.7

7 000

5 000

10.6

3.5

9.0

7 000

5 000

Note: These values are for wet service conditions and standard term duration of load.

9.14.4 Design 9.14.4.1 General In addition to meeting the requirements of Clauses 9.14.4.2 and 9.14.4.3, the design of wood piles and pile groups shall meet the requirements of Section 6.

9.14.4.2 Embedded portion The portion of a pile permanently in contact with a soil mass that provides adequate lateral support shall be designed as a short column using the specified strengths in Table 9.17. The factored resistance of an end-bearing pile shall be calculated on the basis of the minimum cross-section. The factored resistance of a friction pile shall be calculated on the basis of the cross-section located one-third of the thickness of the supporting stratum above the tip.

9.14.4.3 Unembedded portion The portion of a pile in contact with air, water, or a soil mass not providing adequate lateral support shall be designed as a tapered column in accordance with Clause 9.8 using the specified strengths in Table 9.17.

9.15 Fastenings 9.15.1 General The design of fastenings shall be in accordance with CAN/CSA-O86. Glulam rivets shall not be used in bridge structures with a design life of more than two years. Truss nail plates shall not be used in bridge structures with a design life of more than two years, except as specified for wood-concrete composite decks in accordance with Clause 9.22.2.2.3.

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9.15.2 Design The design requirements and factored resistances for fastenings shall be in accordance with CAN/CSA-O86 and use the applicable modification factor for duration of load specified in Clause 9.5.3. The service condition factor for fastenings shall be determined from CAN/CSA-O86 for wood that is assumed to be seasoned at the time of fabrication and used in wet service conditions.

9.15.3 Construction The construction details of fastenings shall be in accordance with CAN/CSA-O86.

9.16 Hardware and metalwork All steel plates, shapes, and welded assemblies shall be designed in accordance with Section 10.

9.17 Durability 9.17.1 General Except as specified in Clauses 9.17.2, 9.17.6, 9.17.9, and 9.17.12, or as otherwise Approved, all wood in permanent structures shall be preservative treated in accordance with the CSA O80 Series of Standards. One of the following preservatives shall be used: (a) creosote; (b) pentachlorophenol in Type A hydrocarbon solvent; (c) copper naphthenate in Type A hydrocarbon solvent; (d) chromated copper arsenate (CCA); (e) ammoniacal copper zinc arsenate (ACZA); (f) alkaline copper quaternary (ACQ) (if approved by Health Canada’s Pest Management Regulatory Agency); or (g) copper azole type B (CA-B) (if approved by Health Canada’s Pest Management Regulatory Agency). The net retention of preservatives shall be the minimum specified in the CSA O80 Series of Standards for the applicable conditions and wood species. Preservative treatment of laminated veneer lumber and parallel strand lumber (see Clause 9.13.1) shall be in accordance with the CSA O80 Series of Standards and Clauses 9.17.5 and 9.17.6. All treated wood shall be substantially devoid of free surface preservative liquid and preservative deposits. All treated wood shall be inspected by qualified personnel in accordance with the CSA O80 Series of Standards or the applicable AWPA Standards.

9.17.2 Pedestrian contact Main structural members shall not be exposed to direct contact by pedestrians in a pedestrian walkway. For components subject to direct pedestrian contact, one of the following preservatives shall be used: (a) chromated copper arsenate (CCA); (b) ammoniacal copper zinc arsenate (ACZA); (c) alkaline copper quaternary (ACQ) (if approved by Health Canada’s Pest Management Regulatory Agency); or (d) copper azole type B (CA-B) (if approved by Health Canada’s Pest Management Regulatory Agency). The net retention of preservatives shall be the minimum specified in the CSA O80 Series of Standards for the applicable conditions and wood species.

9.17.3 Incising All sawn wood and glued-laminated members shall be incised before treatment in accordance with the CSA O80 Series of Standards. Members made of laminated veneer lumber and parallel strand lumber shall not be incised.

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Glued-laminated members too large to be mechanically incised shall be incised by hand throughout the area of contact with caps, sills, or hold-down brackets in accordance with the CSA O80 Series of Standards. The incising requirements shall be noted on the Plans.

9.17.4 Fabrication Except for fabrication that cannot be accurately detailed before erection, all treated wood shall be cut to finished size. All surfacing, holes, notches, ring grooves, chamfering, daps, and other cuts shall be made before pressure preservative treatment. Fabrication drawings shall detail the shape and fabrication requirements of members with the aim of eliminating or minimizing the need for field fabrication. Except when unavoidable, components shall not be cut to length in the field. The fabrication requirements shall be noted on the Plans.

9.17.5 Pressure preservative treatment of laminated veneer lumber Treatment shall be in accordance with CSA O80.9, with retentions as specified in Table 1 of CSA O80.9. For the purpose of penetration sampling, three increment borer samples shall be taken from each member in a treating cylinder charge at the centreline of each side perpendicular to the veneers and approximately at the quarter-length points of the member. If a minimum of five of the six borings show preservative penetration in three outer veneers, the member shall be considered to have met the penetration requirement. Non-conforming members shall be re-treated.

9.17.6 Pressure preservative treatment of parallel strand lumber Treatment shall be in accordance with AWPA C33.

9.17.7 Field treatment The Plans shall specify that all cuts, bore holes, and other field fabrication exposing untreated wood surfaces shall be field treated. Creosote and copper naphthenate shall be the only permitted field preservatives. Creosote shall be the preferred preservative for structural members but shall not be used on components subject to direct pedestrian contact. Copper naphthenate may be used on field cuts of all bridge components. The instructions on the product label shall be adhered to and a minimum of two preservative coats shall be applied.

9.17.8 Treated round wood piles Round wood piles shall be treated in accordance with CSA O80.3.

9.17.9 Untreated round wood piles Untreated round wood piles used in permanent structures shall be clean-peeled and free from wood-destroying organisms. The cut-off shall be below a known permanent water level and the pile shall be completely embedded in soil.

9.17.10 Pile heads After the final cut-off has been made, pile heads shall be given two saturation coats of creosote, followed by the application of a saturation coat of coal-tar pitch. There shall be an interval between applications sufficient to permit drying of each coat before the succeeding one is applied.

9.17.11 Protective treatment of hardware and metalwork 9.17.11.1 Wood treated with creosote, pentachlorophenol, or copper naphthenate Except for nails, spikes, and sheet metal fastenings, all hardware and metalwork used in permanent structures shall be hot-dipped galvanized in accordance with CAN/CSA-G164. Nails and spikes shall be November 2006

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hot-dipped galvanized in accordance with CSA B111 and truss plates shall be galvanized in accordance with ASTM A 653/A 653M for the G90 coating class.

9.17.11.2 Wood treated with CCA, ACZA, ACQ, or CA-B Because of the high copper and zinc content of this group of preservatives (particularly ACZA, ACQ, and CA-B), there is a risk of corrosion of metal items in contact with such preservatives. Accordingly, hot-dipped galvanized or (preferably) stainless steel fasteners, hardware, and metalwork are necessary. Except for nails, spikes, and sheet metal fastenings, all hardware and metalwork used in permanent structures shall be hot-dipped galvanized in accordance with CAN/CSA-G164. Nails and spikes shall be 304 or 316 stainless steel or hot-dipped galvanized to CSA B111. Sheet metal fastenings shall be 304 or 316 stainless steel or hot-dipped galvanized in accordance with ASTM A 653/A 653M for the G185 coating class.

9.17.11.3 Galvanized nuts Galvanized nuts shall be retapped to allow for the increased diameter of the bolt due to galvanizing. Heat-treated alloy components and fastenings shall be protected by an Approved protective treatment.

9.17.12 Stress-laminated timber decking Because of the need for dimensional stability, stress-laminated timber decking shall be treated with one of the following oil-borne preservatives: (a) creosote; (b) pentachlorophenol in Type A hydrocarbon solvent; or (c) copper naphthenate in Type A hydrocarbon solvent. Water-borne preservatives may also be used, provided that the decking is adequately sealed with an Approved product and measures are taken to ensure that prestress levels are maintained. The net retention of preservatives shall be the minimum specified in the CSA O80 Series of Standards for the applicable conditions and wood species.

9.18 Wood cribs 9.18.1 General Wood cribs shall be assumed to act as a unit and shall be designed to resist overturning and sliding. Headers and stretchers shall be designed to resist the bending and shearing load effects and to provide adequate bearing. Vertical spacing between members shall be small enough to retain the fill. The crib shall be closed-faced where an ice problem is anticipated.

9.18.2 Member sizes and assembly Members for wood cribs shall have a minimum dimension of 184 mm. Stretchers shall be as long as practicable to achieve continuity. Joints in each tier of the crib shall be staggered with respect to joints in adjacent tiers.

9.18.3 Fastening Members shall be connected by drift pins at least 19 mm in diameter and of sufficient length to extend completely through one tier and at least three-quarters of the way through the next member.

9.18.4 Load transfer to cribs Load transfer from the superstructure to the top of the crib shall be effected by spreader beams or other bearing devices situated as near to the middle of the crib as possible.

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9.19 Wood trestles 9.19.1 General Piles for trestles shall be designed in accordance with Clauses 9.8 and 9.14. Tops of piles not otherwise encased shall be fitted with snug steel collars with a minimum cross-section of 5 × 75 mm. Caps, sills, and decks shall be securely fastened in accordance with Section 3 to resist uplift forces due to buoyancy.

9.19.2 Pile bents Pile bents higher than 3.0 m shall be braced transversely in accordance with Clause 9.19.5. Longitudinal bracing shall be provided unless a detailed analysis shows that it can be omitted.

9.19.3 Framed bents 9.19.3.1 Supports Framed bents shall be supported on piles, concrete pedestals, or, where appropriate, mudsills. All bents shall be braced transversely and longitudinally in accordance with Clause 9.19.5. 

9.19.3.2 Sills Sills shall be connected to piles or mudsills by drift pins that are at least 19 mm in diameter and extend at least 300 mm into the pile and at least 150 mm into the mudsill. Sills shall be connected to concrete pedestals by anchor rods that are at least 19 mm in diameter and spaced at 1.8 m or less.

9.19.3.3 Post connections Posts shall be connected to sill beams by clip angles, steel dowels, or drift pins that are at least 19 mm in diameter and extend at least 300 mm into the post and at least 150 mm into the sill.

9.19.4 Caps Caps shall be connected to the piles or posts by steel drift pins that are at least 19 mm in diameter and extend at least 300 mm into the pile or post.

9.19.5 Bracing 9.19.5.1 Transverse bracing Diagonal bracing shall be provided on each side of a bent and shall have a minimum cross-section of 75 × 200 mm. The bracing shall be adequately bolted to the posts, piles, caps, and sills. The bolts shall be at least 19 mm in diameter. Where multiple-storey bracing is required, horizontal bracing members of the same size as the diagonal bracing shall be placed between tiers.

9.19.5.2 Longitudinal bracing The requirements for longitudinal bracing shall be determined from analysis. The diagonal braces shall have a minimum cross-section of 75 × 200 mm. The horizontal braces shall have a minimum cross-section of 150 × 200 mm.

9.20 Stringers and girders 9.20.1 Design details The Plans shall specify that the stringers are to be sized to permit even bearing and to compensate for variations in stringer depths at supports.

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All stringers and girders shall be securely fastened in accordance with Section 3 to resist buoyancy effects. Bolts or drift pins shall be at least 19 mm in diameter and shall extend at least 150 mm into the cap at each end of a wood stringer.

9.20.2 Diaphragms Stringers and girders shall be provided with diaphragms at each support. Unless otherwise Approved, intermediate diaphragms shall be provided at the midpoint for spans less than 12 m and at the one-third span point for spans 12 m or more. Diaphragms shall be made of solid sawn wood, solid glued-laminated timber, or steel frames. Wood frame systems shall not be used.

9.21 Nail-laminated wood decks 9.21.1 General Clauses 9.21.2 and 9.21.3 shall apply to wood decks composed of nail-laminated dimension lumber. Where the wood deck surface is exposed to traffic, the depth of the deck shall be increased by 15 mm to allow for wear.

9.21.2 Transversely laminated wood decks 9.21.2.1 General The laminates shall be between 38 and 51 mm thick and have a minimum width of 89 mm. The difference in widths of the deck laminates shall not exceed 5 mm.

9.21.2.2 Assembly 9.21.2.2.1 Nailing Common nails shall be used to fasten each lamination to the preceding one at intervals not exceeding 250 mm. The nails shall be driven alternately near the top and bottom edges. The nails shall be of sufficient length to pass through two laminates and at least halfway through the third. At least one nail shall be placed within 100 to 125 mm of the end of each lamination.

9.21.2.2.2 Deck support anchorage with wood stringers Laminates shall be securely fastened to wood stringers by bolts, lag screws, lugs, or angles or by each of the laminates being toe-nailed with 100 mm nails as follows: (a) one nail at every support for a stringer or girder spacing not exceeding 1.2 m; and (b) two nails at every support for a stringer or girder spacing exceeding 1.2 m.

9.21.2.2.3 Deck support anchorage with steel stringers Laminates shall be securely fastened to the top flanges of steel stringers by (a) bolts; (b) lag screws; (c) plates; (d) angles; or (e) galvanized steel nailing clips that are least 2 mm thick (see Figure 9.1), spaced at 450 mm intervals along each side of the steel beam, and staggered by 225 mm.

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20 mm (max.)

Two nails at 100 mm

Canadian Highway Bridge Design Code

50 to 60 mm

Top surface of wood deck Galvanized steel nailing clip (minimum thickness 2 mm)

40 to 50 mm

40 to 50 mm 40 mm (min.) 50 50 mm mm (min.) (min.)

Additional nail for decks with wood laminates at least 235 mm wide Steel beam

Figure 9.1 Connection of nail-laminated deck to steel beam (See Clause 9.21.2.2.3.)

9.21.2.2.4 Laminate placement Each laminate shall be vertical, tight against the preceding one, and bear evenly on all supports.

9.21.2.2.5 Butt joints Butt joints shall be staggered in such a way that within any band with a width of 1.0 m measured along the laminate, a butt joint shall not occur in more than one laminate out of any three adjacent laminates.

9.21.3 Longitudinal nail-laminated wood decks Longitudinal nail-laminated wood decks shall be used only when made composite with a concrete overlay in accordance with Clause 9.22 or when an Approved alternative method of providing load sharing among the laminates is used. Butt joints shall comply with Clause 9.21.2.2.5.

9.22 Wood-concrete composite decks 9.22.1 General Clause 9.22.2 shall apply to nail-laminated wood decks that are longitudinally laminated and are made composite with a reinforced concrete overlay.

9.22.2 Wood base 9.22.2.1 General The wood base shall consist of longitudinally laminated dimension lumber that is 38 to 51 mm thick and 140 to 292 mm wide.

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9.22.2.2 Assembly 9.22.2.2.1 General The requirements of Clauses 9.21.2.2.1 and 9.21.2.2.4 shall apply.

9.22.2.2.2 Butt joints Butt joints shall meet the requirements of Clause 9.21.2.2.5.

9.22.2.2.3 Spliced butt joints Butt joints shall be provided with a connection detail as shown in Figure 9.2 or spliced in accordance with an Approved method. Steel nail plates shall be installed using a hydraulic press that applies uniform pressure or using an Approved alternative method. t

Galvanized nail plate

Minimum 0.7b

Width b

Minimum 2b

Deck laminated

Section at butt joint

Thickness of laminate, t, mm

Minimum base steel nominal thickness, mm

38–45

1.3

46–51

1.6

Figure 9.2 Spliced butt joint (See Clause 9.22.2.2.3.)

9.22.2.2.4 Deck anchorage The wood base shall be supported on wood-bearing members and the laminates shall be toe-nailed with 100 mm common nails as follows: (a) one nail at (i) each support for each lamination that is continuous over the support; and (ii) each abutment; (b) one nail in each butting lamination at joints over the supports; and (c) additional attachment provided to account for the effects of buoyancy if the superstructure is expected to be submerged.

9.22.3 Concrete slab 9.22.3.1 Strength The concrete shall have a minimum specified strength of 30 MPa.

9.22.3.2 Thickness The minimum thickness of the concrete slab shall be 125 mm.

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9.22.3.3 Reinforcement The minimum reinforcement in the concrete slab shall consist of a mat of 10M bars placed at 180 mm centres in both directions. Where the deck is continuous over a support, the tensile steel shall be designed to provide the required factored flexural resistance. Additional reinforcement, when necessary, shall be placed on top of the mat. Concrete cover to the top of the deck shall be in accordance with Section 8. Concrete cover to the wood-concrete interface shall not be restricted, except that in the case of the form of construction shown in Figure 9.4, the reinforcement shall not bear directly on the wood base.

9.22.4 Wood-concrete interface The wood base and the concrete slab shall be connected in such a manner as to prevent separation and to resist the factored horizontal shear forces between the two materials under repeated loads. This requirement shall be considered satisfied if one of the following methods is used: (a) The wood base consists of laminates that alternate in width by at least 50 mm to form longitudinal grooves. The top surfaces of all laminates are dapped and the sides of the higher laminates are grooved as shown in Figure 9.3. (b) The wood base consists of laminates of substantially equal width, with variations in width not exceeding 5 mm. The top surface of the laminates have transverse grooves 38 mm deep, 150 mm wide, and spaced approximately 600 mm centre to centre. Common spikes at least 50 mm longer than the width of the laminates are driven into alternate laminates to provide shear key reinforcement in accordance with Figure 9.4. Where the grooves in adjacent laminates are staggered by more than 50 mm, all laminates involved are provided with shear key reinforcing nails. 38 mm (min.)

150 mm 150 mm (typ.)

12 mm (min.) 125 mm (min.) Width of groove, 12 mm (min.) Rebar

Alternating laminations

Depth of groove, 6 to 7 mm

Figure 9.3 Details of wood-concrete interface (See Clause 9.22.4.)

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End distance, 600 mm (approx.)

38 mm (approx.)

Spacing, 600 mm (approx.) Approx. 25 mm

150 mm (typ.) (approx.)

Support 125 mm (min.) Approx. 30°

Rebar

Shear key reinforcing nail; spike inclined toward nearest support, including internal support

Figure 9.4 Alternative details of wood-concrete interface (See Clauses 9.22.3.3 and 9.22.4.)

9.22.5 Factored moment resistance 9.22.5.1 General The factored moment resistance of the composite section shall be calculated using the method of transformed sections. The modulus of elasticity for concrete, Ec , shall be obtained from Section 8, the modulus of elasticity for wood shall be E50 and obtained from Table 9.12, and the modulus of elasticity for steel, Es , shall be taken as 200 000 MPa.

9.22.5.2 Factored positive moment resistance Clause 9.22.5.1 shall be considered satisfied if the factored positive moment resistance, Mu , is calculated as follows: Mu = φ kd km ksb fbu Sb where φ is obtained from Table 9.1 for dimension lumber, fbu is obtained from Table 9.12, kd is in accordance with Clause 9.5.3, km is in accordance with Clause 9.5.6, and ksb is obtained from Table 9.4. The elastic section modulus, Sb , with respect to the bottom of the composite section shall be obtained by transforming the concrete into an equivalent area of wood. Only the net section of the wood base shall be considered; the capacity of spliced butt joints shall be ignored.

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9.22.5.3 Factored negative moment resistance Clause 9.22.5.1 shall be considered satisfied if the factored negative moment resistance, Mu , is taken as the smaller of Mu = φ kd km ksb fbu Sb and

Mu = fsfy

E 50St Es

where, φ , fbu , kd , km , and ksb are in accordance with Clause 9.22.5.2, φ s is the resistance factor for steel in tension (see Clause 8.4.6), and fy is the yield strength of the steel specified in Clause 10.5. The elastic section moduli, Sb and St , with respect to the top and bottom of the composite section, respectively, shall be obtained by transforming the steel into an equivalent area of wood. Where the method described in Clause 9.22.4(b) applies, only the portion of the wood below the bottom of the grooves shall be considered.

9.23 Stress-laminated wood decks 9.23.1 General Clause 9.23.2 to 9.23.8 shall apply to vertically laminated wood decks that are post-tensioned perpendicular to the direction of laminates.

9.23.2 Post-tensioning materials 9.23.2.1 Post-tensioning steel Post-tensioning steel shall be high-strength bars satisfying the requirements of CSA G279.

9.23.2.2 Anchorages The dimensions and all details of the anchorages, including the details of the load distribution bulkhead, shall be subject to Approval. Anchorages shall be capable of developing 95% of the ultimate strength of the bars. After tensioning and seating, anchorages shall transmit applied loads without slippage, distortion, or other changes that would contribute to loss in bar force.

9.23.2.3 Couplers Couplers shall be capable of developing 95% of the ultimate strength of the uncoated tendons.

9.23.2.4 Stress limitations The stress in the post-tensioning steel shall not exceed fpy , 0.85fpu at jacking, or 0.80fpu at transfer. Where coating or galvanizing of the bar reduces the anchorage or coupler capacity, these maximum values shall be reduced accordingly.

9.23.3 Design of post-tensioning system 9.23.3.1 General The post-tensioning system may be external or internal and shall be as shown in Figure 9.5 or 9.6.

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Anchorage plate

Support

s Span Neoprene washers

w

Lp

Minimum 0.65b

Minimum channel depth, dc , 0.85b

Minimum 0.65w

Width laminations, b

Galvanized washer

tp

Protective tube filled with nonsetting paste Steel channel bulkhead Anchorage plate Wood bearing block Prestressing tendon

Anchorage nut

Wood bearing block

5 mm minimum

Figure 9.5 External post-tensioning system (See Clauses 9.23.3.1, 9.23.4.4.2, 9.23.4.4.3, 9.23.4.4.6, and 16.9.3.) Anchorage plate (typ.)

s Span

w

Anchorage plate

Anchorage nut

Anchorage plate

Steel channel bulkhead

0.5b

Width laminations, b

Lp

Minimum channel depth, dc , 0.85b

tp

Maximum diameter prestressing hole, Dh = 0.2b

Figure 9.6 Internal post-tensioning system (See Clauses 9.23.3.1, 9.23.4.4.2, 9.23.4.4.3, and 16.9.3.)

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9.23.3.2 Steel/wood ratio The steel/wood ratio, Ar , being As /Aw , shall not exceed 0.0016.

9.23.3.3 Distributed normal pressure on laminates The maximum value of the normal pressure Nj at jacking, assumed to be uniformly distributed over an area s × b, shall be 0.25fql , where fql is obtained from Table 9.18. The minimum final pressure, Nf , assumed to be uniformly distributed, shall be taken as 0.4Nj . Nf shal l not be less than 0.35 MPa.

Table 9.18 Limiting pressure perpendicular to grain, fql , MPa (See Clauses 9.23.3.3 and 9.23.4.2.) Species or species combination

fql

Douglas fir or larch Hem-Fir Lodgepole pine Jack pine Red pine White pine

6.2 5.5 4.4 6.2 6.2 4.4

9.23.3.4 Stressing procedure The stressing of stress-laminated wood decks shall be accomplished by hydraulic jacks. High-strength bars shall be stressed to the forces specified on the Plans. The tensioning shall be performed in the following sequence: (a) the initial stressing, at the time of construction of the deck, shall consist of two stressing operations conducted not less than 12 h apart; (b) the first restressing shall be conducted not less than two weeks after completion of the initial stressing; and (c) the second restressing shall be conducted not less than four weeks after the first restressing. The variation of the prestressing force from the specified values in each bar shall not exceed ± 5%. The time between restressing operations shall not include any time during which the ambient temperature is below 0 °C.

9.23.4 Design of distribution bulkhead 9.23.4.1 General Prestressed distribution bulkheads shall be of steel and shall extend along the full length of both edges of the decks.

9.23.4.2 Factored bearing resistance to post-tensioning forces The factored resistance of the wood in bearing, Rr , due to post-tensioning forces shall be Rr = φ fql Ab where φ is the value for compression perpendicular to grain obtained from Table 9.1, fql is obtained from Table 9.18, and Ab is obtained from Clause 9.23.4.3. The load factor for the post-tensioning force shall be taken as the maximum specified in Section 3 for secondary prestressing effects.

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9.23.4.3 Bearing area for post-tensioning force When the bulkhead satisfies the requirements of Clause 9.23.4.4, the bearing area, Ab , shall be Ab = b bL b where bb and Lb are as specified in Clause 9.23.4.4.5.

9.23.4.4 Steel channel bulkhead 9.23.4.4.1 General Clause 9.23.4.1 shall be considered satisfied if the distribution bulkhead consists of a steel channel and steel anchorage plates in accordance with Clauses 9.23.4.4.2 to 9.23.4.4.6.

9.23.4.4.2 Channel The depth of the steel channel bulkheads, dc , as shown in Figures 9.5 and 9.6 shall be at least 85% of the width of the edge lamination, b, but shall not exceed b. The minimum section properties of the channel shall be obtained from Table 9.19.

Table 9.19 Minimum section properties for steel channel bulkheads (See Clause 9.23.4.4.2.)

Depth of laminated deck, mm

Minimum moment of inertia (about the minor axis) of the channel, mm4

Minimum web thickness, mm

184 235 286

550 000 1 000 000 1 400 000

9.5 11.0 11.0

9.23.4.4.3 Anchorage plate The ratio of the length, Lp , and width, w, of the anchorage plate shown in Figures 9.5 and 9.6 shall satisfy

1 .0 ≤

Lp w

≤ 2 .0

The thickness of the anchorage plate, tp , shall be not less than Lp /12.

9.23.4.4.4 Spacing of post-tensioning anchorages The spacings between post-tensioning anchorages shall (a) not exceed six times the depth of the wood deck; (b) not be less than 2.5 times the depth of the wood deck; (c) not exceed 1.50 m; and (d) not be less than 15Dh in internal systems.

9.23.4.4.5 Effective bearing area The width, bb , of the direct bearing area on the edge lamination shall be taken as the height of the steel channel. The length, Lb , of the direct bearing area along the channel shall be taken as the length, Lp , of the anchorage plate plus twice the thickness of the web of the channel for an internal system, or the width, w, of the anchorage plate plus twice the width of the flange of the channel for an external system.

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9.23.4.4.6 Web stiffening In external post-tensioning systems, the web of the steel channel shall be stiffened beneath the anchorage plate to transmit prestress forces to the flanges and the web of the channel. This requirement shall be considered satisfied if (a) a wood bearing block is provided in accordance with Figure 9.5, with the grain oriented parallel to the applied load; (b) the cross-sectional dimensions of the wood bearing block are, respectively, not less than 65% of the depth of the channel and not less than 65% of the width, w, of the anchorage plate; (c) the thickness of the wood bearing block is such that before stressing it protrudes at least 5 mm beyond the flanges of the channel; and (d) the bearing pressure on the wood bearing block at jacking does exceed the applicable value of fpu specified in Table 9.13 or 9.14.

9.23.5 Laminated decks 9.23.5.1 General Clause 9.22.2.2.2 shall apply to all stress-laminated decks.

9.23.5.2 Lamination dimensions Decking shall consist of laminated dimension lumber 38 to 76 mm thick, at least 184 mm wide for longitudinally laminated decks, and at least 140 mm wide for transversely laminated decks.

9.23.5.3 Holes in laminates for internal systems The diameter of holes, Dh , drilled in laminated decking for an internal prestressing system shall not exceed 20% of the width of the laminates.

9.23.5.4 Nailing Each laminate shall be fastened to the preceding one by nails driven in two rows, one near the top and one near the bottom edges of the laminates. The nails shall be staggered between the rows and within each row the spacing shall not exceed 500 mm. The nails shall be long enough to pass through at least two laminates, but shall not be longer than 152 mm. For power-driven nails, the specified spacing shall be adjusted in proportion to the cross-sectional area of the power nails and the same size standard spiral nails.

9.23.5.5 Support anchorage Decks shall have a support anchorage system that can be either installed or engaged after the stressing of the post-tensioning bars specified in Clause 9.23.3.4. During assembly, stress-laminated wood decks shall not be anchored to the supports, except as specified in Clause 9.23.5.7. The deck support anchorage shall be designed to resist the factored force effects specified in Section 3 and shall meet the following minimum requirements: (a) The deck shall be secured to each supporting member at intervals of not more than 1 m with the equivalent of two 19 mm diameter bolts (for decks up to 235 mm deep) or two 25 mm diameter bolts (for decks more than 235 mm deep). (b) Where the spacing of the supporting members, measured parallel to the span of the deck, is less than 2 m, the spacing of the anchorages shall not be less than 2 m and the anchors shall be staggered by 1 m between adjacent supporting members.

9.23.5.6 Deck attachment The deck shall not be attached to the supporting members, except as specified in Clause 9.23.5.5, until after the first restressing. When a deck requires restraint against buckling during stressing, the restraint shall not prevent free movement of the deck perpendicular to the laminates.

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9.23.5.7 Transversely laminated decks The length of decking perpendicular to the laminate length shall not exceed 40 times the width of the laminate unless restraint against buckling is provided or the deck is constructed in segments in accordance with Clause 9.23.5.8.

9.23.5.8 Segmental construction When a deck is to be constructed in segments, each segment shall undergo the restressing specified in Clause 9.23.3.4 before being installed. The method of installation of the segments shall be such that the final assembled deck will be continuous. When the method of installation requires the temporary release of stressing in a segment to facilitate installation, that segment shall then be stressed twice before any segments are attached to it. The first stressing shall be at the time of installation of the segment. The second stressing shall be performed not sooner than 4T after the first stressing, where T equals the total time for which the segment was not under stress.

9.23.6 Net section When the factored flexural resistance of the deck is calculated, a section perpendicular to the laminates and incorporating butt joints shall be considered. For the post-tensioning bars, the effects of holes shall be ignored.

9.23.7 Hardware durability All steel components of the post-tensioning system shall meet the requirements of Section 10. In addition, all bars of external systems shall be protected by a system equivalent to that shown in Figure 9.7. The protective tubing shall be sealed against moisture penetration by neoprene seals and shall have a collapsible connection to facilitate movement during stressing of the bars. The anchorages of internal and external systems shall be protected by a system equivalent to that shown in Figure 9.7. The anchorages of transversely laminated decks shall be protected from the effects of traffic.

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Sliding connection closes during stressing

Protective tubing

Heavy seamless steel pipe (minimum wall thickness, 8 mm)

Cut-away section

Neoprene washers

Galvanized washer

Protective tubing Prestressing bar Minimum of two neoprene O-rings, 6 mm thick Seamless pipe welded all around to anchorage plate

Anchorage plate

Protective tube filled with non-setting paste

Figure 9.7 Protection for external post-tensioning system (See Clause 9.23.7.)

9.23.8 Design details 9.23.8.1 Curbs and barriers Curbs and barriers shall not be connected directly to the steel distribution bulkhead.

9.23.8.2 Containment of failed prestressing components The steel distribution bulkhead shall be designed to restrain all post-tensioning components in the event of their failure. The restraint shall be removable to enable access to the anchorages.

9.24 Wearing course A wearing course of untreated wood, plant-mix asphalt, asphalt planks, tar and chips, concrete, or an Approved material shall be used on all wood bridges other than those of wood-concrete composite construction.

9.25 Drainage 9.25.1 General Positive drainage paths shall be provided to ensure drainage away from all primary components of the structure.

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9.25.2 Deck The crown and crossfall of the deck shall meet the requirements of Section 1. Where deck drains are not provided, the anchorage of the curb to the deck shall be such that a minimum vertical gap of 150 mm is provided between the curb and the wearing surface for an aggregate length equal to at least one-half the length of the deck.

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

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Section 10 — Steel structures 10.1 10.2 10.3 10.3.1 10.3.2 10.4 10.4.1 10.4.2 10.4.3 10.4.4 10.4.5 10.4.6 10.4.7 10.4.8 10.4.9 10.4.10 10.4.11 10.4.12 10.4.13 10.5 10.5.1 10.5.2 10.5.3 10.5.4 10.5.5 10.5.6 10.5.7 10.5.8 10.5.9 10.6 10.6.1 10.6.2 10.6.3 10.6.4 10.6.5 10.6.6 10.6.7 10.7 10.7.1 10.7.2 10.7.3 10.7.4 10.7.5 10.8 10.8.1 10.8.2 10.8.3 10.8.4 10.9 10.9.1 10.9.2

Scope 428 Definitions 428 Abbreviations and symbols 430 Abbreviations 430 Symbols 430 Materials 437 General 437 Structural steel 437 Cast steel 437 Stainless steel 438 Bolts 438 Welding electrodes 438 Stud shear connectors 438 Cables 438 High-strength bars 438 Galvanizing and metallizing 438 Identification 438 Coefficient of thermal expansion 439 Pins and rollers 439 Design theory and assumptions 439 General 439 Ultimate limit states 439 Serviceability limit states 439 Fatigue limit state 439 Fracture control 440 Seismic requirements 440 Resistance factors 440 Analysis 440 Design lengths of members 440 Durability 441 General 441 Corrosion as a deterioration mechanism 441 Corrosion protection 441 Superstructure components 441 Other components 442 Areas inaccessible after erection 444 Detailing for durability 444 Design details 444 General 444 Minimum thickness of steel 444 Floor beams and diaphragms at piers and abutments 445 Camber 445 Welded attachments 446 Tension members 446 General 446 Axial tensile resistance 447 Axial tension and bending 447 Tensile resistance of cables 447 Compression members 447 General 447 Width-to-thickness ratio of elements in compression 448

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10.9.3 10.9.4 10.9.5 10.10 10.10.1 10.10.2 10.10.3 10.10.4 10.10.5 10.10.6 10.10.7 10.10.8 10.10.9 10.11 10.11.1 10.11.2 10.11.3 10.11.4 10.11.5 10.11.6 10.11.7 10.11.8 10.11.9 10.12 10.12.1 10.12.2 10.12.3 10.12.4 10.12.5 10.12.6 10.12.7 10.12.8 10.13 10.13.1 10.13.2 10.13.3 10.13.4 10.13.5 10.13.6 10.13.7 10.13.8 10.14 10.14.1 10.14.2 10.14.3 10.15 10.15.1 10.15.2 10.15.3 10.15.4 10.15.5 10.16 10.16.1 10.16.2

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Axial compressive resistance 450 Axial compression and bending 451 Composite columns 453 Beams and girders 455 General 455 Class 1 and 2 sections 455 Class 3 sections 457 Stiffened plate girders 457 Shear resistance 458 Intermediate transverse stiffeners 459 Longitudinal web stiffeners 460 Bearing stiffeners 461 Lateral bracing, cross-frames, and diaphragms Composite beams and girders 463 General 463 Proportioning 463 Effects of creep and shrinkage 463 Control of permanent deflections 463 Class 1 and Class 2 sections 463 Class 3 sections 467 Stiffened plate girders 469 Shear connectors 470 Lateral bracing, cross-frames, and diaphragms Composite box girders 472 General 472 Effective width of tension flanges 472 Web plates 472 Flange-to-web welds 472 Moment resistance 472 Diaphragms, cross-frames, and lateral bracing Multiple box girders 475 Single box girders 475 Horizontally curved girders 476 General 476 Special considerations 476 Design theory 477 Bearings 477 Diaphragms, cross-frames, and lateral bracing Steel I-girders 478 Composite box girders 480 Camber 482 Trusses 482 General 482 Built-up members 482 Bracing 483 Arches 484 General 484 Width-to-thickness ratios 484 Longitudinal web stiffeners 484 Axial compression and bending 484 Arch ties 485 Orthotropic decks 485 General 485 Effective width of deck 485

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10.16.3 10.16.4 10.16.5 10.16.6 10.16.7 10.17 10.17.1 10.17.2 10.17.3 10.17.4 10.18 10.18.1 10.18.2 10.18.3 10.18.4 10.18.5 10.19 10.19.1 10.19.2 10.20 10.20.1 10.20.2 10.21 10.21.1 10.21.2 10.21.3 10.22 10.22.1 10.22.2 10.22.3 10.22.4 10.22.5 10.22.6 10.22.7 10.22.8 10.23 10.23.1 10.23.2 10.23.3 10.23.4 10.23.5 10.23.6 10.24 10.24.1 10.24.2 10.24.3 10.24.4 10.24.5 10.24.6 10.24.7 10.24.8 10.24.9 10.24.10

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Superposition of local and global effects 485 Deflection 486 Girder diaphragms 486 Design detail requirements 486 Wearing surface 487 Structural fatigue 488 General 488 Live-load-induced fatigue 488 Distortion-induced fatigue 500 Orthotropic decks 501 Splices and connections 501 General 501 Bolted connections 502 Welds 504 Detailing of bolted connections 505 Connection reinforcement and stiffening 508 Anchor rods 509 General 509 Anchor rod resistance 509 Pins, rollers, and rockers 510 Bearing resistance 510 Pins 510 Torsion 511 General 511 Members of closed cross-section 511 Members of open cross-section 512 Steel piles 513 General 513 Resistance factors 513 Compressive resistance 513 Unsupported length 513 Effective length factor 513 Splices 513 Welding 513 Composite tube piles 513 Fracture control 514 General 514 Identification 514 Fracture toughness 514 Welding of fracture-critical and primary tension members 515 Welding corrections and repairs to fracture-critical members 516 Non-destructive testing of fracture-critical members 519 Construction requirements for structural steel 519 General 519 Submissions 519 Materials 520 Fabrication 520 Welded construction 523 Bolted construction 524 Tolerances 527 Quality control 528 Transportation and delivery 529 Erection 529

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Section 10 Steel structures 10.1 Scope This Section specifies requirements for the design of structural steel bridges, including requirements for structural steel components, welds, bolts, and other fasteners required in fabrication and erection. Requirements related to the repeated application of loads and to fracture control and fracture toughness for primary tension and fracture-critical members are also specified.

10.2 Definitions The following definitions apply in this Section: Brittle fracture — a type of fracture in structural materials without prior plastic deformation that usually occurs suddenly. Buckling load — the load at which a member or element reaches a condition of instability. Camber — the built-in deviation of a bridge member from straight, when viewed in elevation. Class — a designation of structural sections with regard to the width-to-thickness ratios of their constituent elements and their flexural-compressive behaviour. Coating — an Approved protective system for steel, e.g., galvanizing, metallizing, a paint system, or coal tar epoxy. Composite beam or girder — a steel beam or girder structurally connected to a concrete slab so that the beam and slab respond to loads as a unit. Composite column — a column consisting of a steel tube filled with concrete, with or without internal reinforcement. Critical net area — the area with the least tensile or tensile-shear resistance. Element — a flat plate or plate-like component of a structural member. Erection diagrams — drawings that show the layout and dimensions of a steel structure and from which shop details are made. They also correlate the fabricator’s piece marks with locations on the structure. Fatigue — initiation of microscopic cracks and propagation of such cracks into macroscopic cracks caused by the repeated application of load. Fatigue limit — the level of stress range below which no fatigue crack growth is assumed to occur. Fixed joint — a joint that allows rotation but not translation. Flush — weld reinforcement not exceeding 1 mm in height that has a smooth, gradual transition with the surrounding plate (and involving grinding where necessary). Fracture-critical membersmembers or portions of members, including attachments, in a single load path structure that are subject to tensile stress and the failure of which can lead to collapse of the structure.

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Gauge — the distance between successive holes, measured at right angles to the direction of the force in the member. Lateral torsional buckling — the buckling of a member involving lateral deflection and twisting. Local buckling — the buckling of a plate element (as distinct from the buckling of the member as a whole). Matching electrode — an electrode with an ultimate strength closest to and greater than the minimum specified ultimate strength of the base metal. Notch toughness — the ability of steel to absorb tensile strain energy in the presence of a notch. Post-buckling resistance — the ability of plate elements to resist additional load after initial elastic buckling. Primary tension members — members or portions of members, including attachments (but not fracture-critical members or secondary components) that are subject to tensile stress. Proposal — a constructor’s submission of changes, when engineering design is required, that affects either the original design or the method of construction or shipping of a structure. Prying action — an additional force introduced into fasteners as a result of deformation of the parts that they connect. Single load path structure — a structure in which failure of a single structural component could lead to a total collapse. Slenderness ratio — the effective length of a member divided by the radius of gyration, both with respect to the same axis. Slip-critical connection — a connection where slippage cannot be tolerated, including connections subject to fatigue or to frequent load reversal or where the resulting deflections are unacceptable. Smooth — a profile of weld reinforcement where any uneven surface has been ground away and the remaining metal profile merges gradually with the surrounding plate. In order to be regarded as smooth, weld reinforcements that remain after grinding are limited to 2 mm for plate thicknesses of 50 mm and less and 3 mm for plate thicknesses greater than 50 mm. Snug-tight — the tightness of a bolt that is attained after a few impacts of an impact wrench or the full effort of a person using a spud wrench. Stress range — the algebraic difference between the maximum and the minimum stresses caused by fatigue loading, where tensile stress has the opposite sign to compressive stress. Stress range category — a category that establishes the level of stress range permitted in accordance with the classification of the detail and the number of the design stress cycles. Tension-field action — the truss-like behaviour of a plate girder panel under shear force that develops after shear-buckling of the web and is characterized by diagonal tensile forces in the web and compressive forces in the transverse stiffeners. Web crippling — the local failure of a web plate in the immediate vicinity of a concentrated load or reaction.

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10.3 Abbreviations and symbols 10.3.1 Abbreviations The following abbreviations apply in this Section: CJP — complete joint penetration FLS — fatigue limit state PJP — partial joint penetration SLS — serviceability limit state ULS — ultimate limit state

10.3.2 Symbols The following symbols apply in this Section: A

= area, mm2

A’

= area enclosed by the median line of the wall of a closed section, mm2

Ab

= cross-sectional area of a bolt, based on nominal diameter, mm2

Ac

= area of concrete in a tube pile, mm2; transverse area of concrete between the longitudinal shear planes that define Acv , mm2

Ace

= area of concrete in compression in a composite column, mm2

Acf

= area of compression flange of a steel section, mm2

Acv

= critical area of longitudinal shear planes in the concrete slab, one on each side of the steel compression flange, extending from the point of zero moment to the point of maximum moment, mm2

Ade

= effective cross-sectional area of the deck, including longitudinal ribs, mm2

Af

= area of bottom flange of box girders, including longitudinal stiffeners, mm2; area of flanges of plate girder, mm2

Ag

= gross area, mm2

Agv

= gross shear area for block shear failure (see Clause 10.8.1.3.2.4), mm2

Am

= area of fusion face, mm2

An

= critical net area, mm2; total net area of a member tributary to the particular lap splice, including elements not directly connected, mm2; tensile stress area, mm2



Ane

= effective net area (reduced for shear lag), mm2



An1, An2, An3 = net areas of the connected plate elements subject to load transfer by a transverse weld, two longitudinal welds, or a single longitudinal weld, respectively, mm2





Ar

= area of reinforcing steel within the effective width of a concrete slab, mm2

ArL

= area of longitudinal reinforcement within the concrete area Ac , mm2

Art

= area of transverse reinforcement crossing the longitudinal shear planes of Acv , mm2

As

= area of steel section, mm2; area of stiffener or pair of stiffeners, mm2; tensile stress area of bolt, mm2

Asc

= area of shear connector, mm2

Asc ’

= area of steel section in compression (see Clause 10.11.6.2.2), mm2

Ast

= tensile stress area, mm2

A’st

= area of steel section in tension (see Clause 10.11.6.2.2), mm2

Aw

= web area or shear area, mm2; size of effective throat area of weld, mm2

ADTT

= average daily truck traffic

ADTTf

= single lane average daily truck traffic for fatigue

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a

= spacing of transverse stiffeners, mm; depth of compression block in a concrete slab, mm; transverse distance between centroids of groups of fasteners or welds connecting the batten to each main component, mm; clear distance between webs of a trough at deck level, mm

a’

= the larger of e, the clear distance between stiffener troughs at deck level, and a, the clear distance between webs of a trough at deck level, mm

B

= ratio in interaction equation for composite columns

Be

= effective width of concrete slab, mm

Br

= factored bearing resistance of a member or component, N

B 1, B 2

= geometric coefficients for a laterally unsupported monosymmetric I-beam

b

= half of width of flange of I-sections and T-sections, mm; full width of flange of channels, Z-sections, and stems of tees, mm; distance from free edge of plates to the first line of bolts or welds, mm; width of stiffener, mm; width of bottom flange plate between webs of box girder, mm

bc

= width of concrete at the neutral axis, mm (see Clause 10.9.5.5)

bf

= width of widest flange of curved welded I-girders, mm

bs

= width of compression flange between longitudinal stiffeners, mm; distance from web to nearest longitudinal stiffener, mm

C

= coefficient in formula for area of stiffener; coefficient in formula for moment resistance of unstiffened compression flanges of composite box girders

CL

= correction factor for fatigue truck weight

Cc

= factored compressive resistance of concrete, N

Ce

= Euler buckling load, N

Cec

= Euler buckling load of a concrete-filled hollow structural section, N

Cf

= factored compressive force in a member or component at ULS, N

Cr

= factored compressive resistance of a member or component, N; factored compressive resistance of steel acting at the centroid of the steel area in compression, N; factored compressive resistance of reinforcing steel, N

C r’

= factored compressive resistance of concrete area, Ac , of a column, N

Cr c

= factored compressive resistance of a composite column, N

Crcm

= factored compressive resistance of composite column that can coexist with Mrc when all of the section is in compression, N

Crco

= factored compressive resistance of composite column of zero slenderness ratio, N

Crx

= factored compressive resistance of a member or component about the major axis, N

Cs

= factored compressive force in steel of composite beam when the plastic neutral axis is in the steel section, N; coefficient in equation for moment resistance of stiffened compression flanges of composite box girders

Cw

= warping torsional constant, mm6

Cy

= axial compressive force at yield stress, N

C1, C2

= limiting values of compressive resistance of slab, N

c1

= coefficient related to the slip resistance of a bolted joint

D

= stiffener factor; outside diameter of circular section, mm; diameter of rocker or roller, mm; weld leg size, mm

d

= depth, mm; depth of beam or girder, mm; diameter of bolt or stud shear connector, mm; longitudinal distance centre-to-centre of battens, mm

dc

= depth of compression portion of web in flexure, mm

ds’

= distance from extreme compression fibre to centroid of reinforcing steel, mm

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Ec

= modulus of elasticity of concrete, MPa

Es

= modulus of elasticity of steel, MPa

e

= edge distance, mm; lever arm between the factored compressive resistance, Cr , and the factored tensile resistance, Tr , of the steel, mm; clear distance between stiffener troughs at deck level, mm

e’

= lever arm between the factored compressive resistance, Cr’, and the factored tensile resistance, Tr , of the steel, mm

ec

= lever arm between the factored tensile resistance and the factored compressive resistance of the concrete, mm

er

= lever arm between the factored tensile resistance and the factored compressive resistance of the reinforcing steel, mm

es

= lever arm between the tensile resistance and the compressive resistance of the steel, mm

Fcr

= shear buckling stress, MPa; buckling stress of plate in compression, MPa; lateral torsional buckling stress, MPa

Fe

= critical torsional or flexural torsional elastic buckling stress, MPa

Fex

= elastic flexural buckling stress about the major axis, MPa

Fey

= elastic flexural buckling stress about the minor axis, MPa

Fez

= elastic torsional buckling stress, MPa

Fm

= average of the tensile yield and ultimate strengths, MPa

Fs

= ULS shear stress, MPa

Fsr

= fatigue stress range resistance, MPa

Fsrt

= constant amplitude threshold stress range, MPa

Fst

= factored force in stiffener at ULS, N

Ft

= tension field component of post-buckling stress, MPa

Fu

= specified minimum tensile strength, MPa

Fy

= specified minimum yield stress, yield point, or yield strength, MPa

Fyc

= yield strength of a column, MPa

fb

= calculated bending stress, MPa

f c’

= specified compressive strength of concrete, MPa

fcr

= cracking strength of concrete, MPa

fg

= axial global tensile stress in a deck induced by flexure and axial tension in the main longitudinal girders, MPa

fs

= coexisting shear stress due to warping torsion, MPa

fsr

= calculated FLS stress range at the detail due to passage of the CL-W Truck or of a tandem set of axles, MPa

fvg

= the simultaneous global shear stress in the deck, MPa

fw

= warping normal stress, MPa

fy

= specified minimum yield strength of reinforcing steel, MPa

Gs

= shear modulus of elasticity of structural steel, MPa

g

= transverse spacing between fastener gauge lines, mm; distance from heel of connection angle to first gauge line of bolts in outstanding legs, mm

H

= coefficient for flexural torsional buckling

h

= clear depth of web between flanges, mm; width of rectangular hollow section, mm; height of shear connector, mm; height of stiffener, mm; height of trough, mm

h’

= length of inclined portion of a rib web, mm

hc

= clear depth of column web, mm

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hn

= variable used to calculate Mrc of a circular hollow structural section

hp

= depth of subpanel of a girder, mm

I

= moment of inertia, mm4

Is

= moment of inertia of longitudinal compression flange stiffener, mm4

It

= moment of inertia of transverse compression flange stiffener, mm4; moment of inertia of transformed section, mm4

Ix

= major axis moment of inertia, mm4

Iy

= minor axis moment of inertia of the whole cross-section, mm4

Iy1, Iy2

=

J

= St. Venant torsional constant, mm4

j

= coefficient used in determining moment of inertia of stiffeners

moment of inertia of upper and lower flanges, respectively, about the y-axis of symmetry, mm4

K

= effective length factor

Kx , Ky , Kz

= effective length factor with respect to x-, y-, or z-axis

k

= distance from outer face of flange to toe of flange-to-web fillet, mm

ks

= coefficient related to the slip resistance of a bolted joint; plate buckling coefficient

kv

= shear buckling coefficient

k1, k2

= buckling coefficients

L

= length, mm; span length between simple connections at girder ends, mm; connection length in direction of loading, equal to the distance between the first and last bolts in bolted connections and to the overall length of the weld pattern in welded connections, mm; laterally unsupported distance from one braced location to an adjacent braced location, mm; length of roller or rocker, mm; length of cut-out in a closed cross-section member measured parallel to the longitudinal axis of the member, mm; length of a compression flange between points of lateral restraint, mm

Lc

= length of channel shear connector, mm

Ln

= length of segment parallel to the force, mm



= length in which warping restraint is developed, mm

ML

= bending moment in beam or girder at SLS due to live load, N•mm

Ma

= factored bending moment at one-quarter point of unbraced segment, N•mm



Mb

= factored bending moment at midpoint of unbraced segment, N•mm



Mc

= factored bending moment at three-quarter point of unbraced segment, N•mm

Md

= bending moment in beam or girder at SLS due to dead load, N•mm

Mf

= factored bending moment in member or component at ULS, N•mm

Mfb

= factored bending moment in transverse beam at ULS, N•mm

Mfd

= factored bending moment in beam or girder at ULS due to dead load, N•mm

Mfl

= factored bending moment in beam or girder at ULS due to live load, N•mm

Mfr

= factored bending moment in longitudinal rib at ULS, N•mm

Mfsd

= factored bending moment in beam or girder at ULS due to superimposed dead load, N•mm

Mfw

= factored bending moment in plane of a girder flange due to torsional warping, N•mm

Mfx

= factored bending moment in member or component about the x-axis of the cross-section at ULS, N•mm

Mfy

= factored bending moment in member or component about the y-axis of the cross-section at ULS, N•mm

Mf 1

= smaller factored end moment of beam-column at ULS, N•mm

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



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Mf 2

= larger factored end moment of beam-column at ULS, N•mm

Mp

= plastic moment resistance (= ZFy ), N•mm

Mr

= factored moment resistance of member or component, N•mm

Mrb

= factored moment resistance of transverse beam, N•mm

Mrc

= factored moment resistance of composite column, N•mm

Mrr

= factored moment resistance of longitudinal rib, N•mm

Mrx

= factored moment resistance of member or component about the x-axis of the cross-section, N•mm

Mrx’

= reduced factored moment resistance of curved non-composite I-girder, N•mm

Mry

= factored moment resistance of member or component about the y-axis of the cross-section, N•mm

Msd

= bending moment in beam or girder at SLS due to superimposed dead load, N•mm

Mu

= critical elastic moment of a laterally unbraced beam, N•mm

My

= yield moment, N•mm

m

= number of faying surfaces or shear planes in a bolted joint (equal to one for bolts in single shear and two for bolts in double shear)

N

= length of bearing of an applied load, mm; number of shear connectors

Na

= number of additional shear connectors per beam at point of contraflexure

Nc

= specified number of design stress cycles

Nd

= number of design stress cycles experienced for each passage of the design truck (see Table 10.5)

n

= number of equally spaced longitudinal stiffeners in box girders; number of parallel planes of battens; number of bolts; modular ratio, Es /Ec ; number of studs arranged transversely across a flange at a given location; coefficient for axial buckling resistance

P

= factored force to be transferred by shear connectors, N

p

= pitch of threads, mm; pitch between bolts, mm; reduction factor for multi-lane fatigue loading

Q

= moment of area, about the neutral axis of the composite section, of the transformed compressive concrete area in positive moment regions or in negative moment regions that are prestressed, mm3; for non-prestressed sections in negative moment regions, moment of the transformed area of reinforcement embedded in the concrete, mm3

Qf

= factored torsional moment in a member at ULS, N•mm

Qr

= factored torsional resistance, N•mm

qr

= factored shear resistance of shear connectors, N

qsr

= range of interface shear, N

R

= radius of curvature of girder web, mm (see Clause 10.13.6.1); horizontal radius of curvature, mm (see Clause 10.7.4.3); transition radius as shown in Example 12 of Figure 10.6

Rs

= vertical force for proportioning connection of transverse stiffener to longitudinal stiffener in box girders, at ULS, N

Rv

= reduced normal stress factor, taking coexisting warping shear stresses into account

Rw

= vertical force for proportioning connection of transverse stiffener to web in box girders, at ULS, N (see Clause 10.18.3.2.2); strength reduction factor for multiple orientation fillet welds

R1, R2

= non-dimensional width-to-thickness demarcation ratios between yielding, inelastic buckling, and elastic buckling of compression flange; radius of roller or rocker and of groove of supporting plate, respectively, mm

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May 2010 (Replaces p. 434, November 2006)

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

r

= radius of gyration, mm

rc

= radius of gyration of the concrete area, mm

rx

= radius of gyration of a member about its strong axis, mm

ry

= radius of gyration of a member about its weak axis, mm

r0

= centroidal radius of gyration (see Clause 10.9.3.2), mm

S

= elastic section modulus of steel section, mm3; short-term load, N

S’

= elastic modulus of composite section comprising the steel section, reinforcement, and prestressing steel within the effective width of the slab with respect to the flange or reinforcing steel under consideration, mm3

Se

= effective section modulus, mm3

Sh

= elastic modulus of longitudinal stiffener with respect to the base of the stiffener, mm3

Sn , S3n

= elastic modulus of section comprising the steel beam or girder and the concrete slab, calculated using a modular ratio of n or 3n, respectively, mm3

St

= section modulus of transverse stiffener, mm3

s

= centre-to-centre spacing between successive fastener holes in the line of load, mm; centre-to-centre spacing of each group of shear studs, mm

T

= tension in bolt at SLS, N; total load on column, N

Tf

= factored tensile force in member or component at ULS, N

Tr

= factored tensile resistance of a steel section, member, or component, of reinforcing steel, or of the effective width of a deck, including the longitudinal ribs, N

Ts

= factored tensile resistance of steel section or component, N; minimum service temperature, °C

Tt

= Charpy V-notch test temperature, °C

Tu

= specified minimum tensile resistance, taken as follows: (a) for parallel wire strands, the product of the sum of the areas of the individual wires and the specified minimum tensile strength of the wires, N; and (b) for helical strands and wire ropes, the specified minimum tensile resistance established by test, taking into account the actual configuration such as socketing and bending over cable bands, N



t

= thickness, mm; average thickness of channel shear connector flange, mm; thickness of flange, mm; thickness of end connection angles, mm; thickness of stiffener, mm

tb

= thickness of beam flange, mm; thickness of bottom flange, mm

tc

= thickness of concrete slab, mm; thickness of column flange, mm

tde

= effective thickness of deck plate, taking into account the stiffening effect of the surfacing, mm

tr

= thickness of rib, mm

tt

= thickness of top flange, mm

U

= factor to account for moment gradient and for second-order effects of axial force acting on the deformed member

Ut

= efficiency factor

V

= shear in a bolt or bolts at SLS, N

VH

= horizontal shear between troughs in orthotropic deck bridge due to shear, VLL+I , due to live load and impact, as specified in Table 10.8, N

VLL+I

= shear due to live load and impact, N

Vf

= factored shear force at ULS, N

Vr

= factored shear resistance of member or component, N; shear range, N

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Vs

= slip resistance at SLS, N

Vsr

= range of shear force at FLS resulting from passage of CL-W Truck, N

Vu

= longitudinal shear in concrete slab of a composite beam, N

W

= load level in CL-W, kN

w

= web thickness, mm; thickness of channel shear connector web, mm; width of plate, mm

wc

= thickness of column web, mm

wn

= length of a segment, normal to a force, mm

X

= curvature correction factor for transverse stiffener requirements

Xu

= ultimate strength of weld metal, as rated by electrode classification number, MPa

x

= subscript relating to the strong axis of a member

x

= distance perpendicular to axis of member from the fastener plane to the centroid of the portion of the area of the cross-section under consideration, mm

x0

= x-coordinate of shear centre with respect to centroid, mm

Y

= ratio of specified minimum yield point of web steel to specified minimum yield point of stiffener steel

y

= subscript relating to the weak axis of a member; design life, years

yb

= distance from centroid of a steel section to bottom fibre of a steel beam or girder, mm

yb’

= distance from centroid of the lower portion of a steel section under tension or compression to bottom fibre of a beam or girder, mm

ybc

= distance from plastic neutral axis of a composite section to bottom fibre of a steel beam or girder, mm



yc

= maximum distance from the neutral axis to the extreme outer fibre of the composite section (if applicable), mm



y0

= y-coordinate of shear centre with respect to centroid, mm



ys

= distance from the neutral axis to the extreme outer fibre of the steel section (maximum distance for non-symmetrical sections), mm

yt

= distance from centroid of a steel section to top fibre of a steel beam or girder, mm

y t’

= distance from centroid of the upper portion of a steel section under tension or compression to top fibre of a steel beam or girder, mm

ytc

= distance from plastic neutral axis of a composite section to top fibre of a steel beam or girder, mm

Z

= plastic section modulus of a steel section, mm3; curvature parameter

Zsr

= allowable range of interface shear in an individual shear connector, N

 x    DL SDL

= value derived from a recursive equation, radians (see Clause 10.9.5.5)

m r 

= maximum value of  DL + SDL within length L , mm



= ratio of the smaller factored moment to the larger factored moment at opposite ends of an unbraced length (positive for double curvature and negative for single curvature)

  

436

= coefficient of monosymmetry = fatigue life constant  specified camber at any section, mm = camber at any point along the length of a span  camber at any point along the length L, calculated to compensate for deflection due to dead loads on the composite section (if applicable), mm = additional camber for horizontally heat-curved beams, mm = angle of inclination of web plate of box girders to the vertical, degrees; angle of weld axis to line of action of force, degrees

May 2010 (Replaces p. 436, November 2006)

© Canadian Standards Association

 c e   b,  w , ’

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

= non-dimensional slenderness parameter in column formula; slenderness parameter = slenderness parameter for concrete portion of composite column = equivalent slenderness parameter = factor modifying contribution of steel to compressive resistance of composite column = curvature correction factors = factors modifying contributions of steel and concrete, respectively, to compressive resistance of composite column

b

= resistance factor for bolts

 be

= resistance factor for beam web bearing, end

 bi  br c r s  sc  tc w  1 2

= resistance factor for beam web bearing, interior = resistance factor for load bearing in bolted connections = resistance factor for concrete = resistance factor for reinforcement = resistance factor for steel = resistance factor for shear connectors = resistance factor for steel cables in tension = resistance factor for welds = ratio of total cross-sectional area to that of both flanges = coefficient used to determine equivalent uniform bending effect in beam-columns = coefficient to account for increased moment resistance of a laterally unsupported beam segment when subject to a moment gradient

10.4 Materials 10.4.1 General Clauses 10.4.2 to 10.4.7 shall apply unless deviations from their requirements are Approved. The fracture toughness of steel shall meet the requirements of Clause 10.23.3. Plates provided from coils shall be used only if it can be demonstrated that the levelling process used in manufacturing produces plate with longitudinal residual stresses that are balanced about mid-thickness. In addition, after levelling, plates shall conform to the flatness tolerances specified in CSA G40.20, and the elongation and impact properties, after testing in accordance with CSA G40.20, shall be to the satisfaction of the Engineer. 

10.4.2 Structural steel Structural steel shall conform to CSA G40.21, except as provided below. The modulus of elasticity of structural steel, Es , shall be taken as 200 000 MPa and the shear modulus of elasticity of structural steel, Gs , shall be taken as 77 000 MPa. Weathering steel members shall be of Type A atmospheric corrosion-resistant steel as specified in CSA G40.21. Fracture-critical members and primary tension members shall be of Type AT, Type WT, or Type QT steel as specified in CSA G40.21. ASTM A 588/A 588M steel may be substituted for CSA G40.21 Grade 350A steel. ASTM A 588/A 588M steel may be substituted for CSA G40.21 Grade 350AT steel when the Charpy impact energy requirements are verified by the submission of test documentation.

10.4.3 Cast steel Cast steel shall comply with ASTM A 27/A 27M, ASTM A 148/A 148M, or ASTM A 486/A 486M.

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10.4.4 Stainless steel Stainless steel shall comply with ASTM A 167. 

10.4.5 Bolts Bolts shall comply with ASTM A 325, ASTM A 325M, ASTM A 490, ASTM A 490M, ASTM F 1852, or ASTM F 2280. Bolts less than M16 or 5/8 inch in diameter shall not be used in structural applications. ASTM A 325/A 325M or ASTM A 490/A 490M high-strength bolts for use with uncoated corrosion-resistant steel shall be Type 3 unless corrosion protection is provided by an approved protection system. ASTM A 490 and A 490M bolts shall not be galvanized or plated.



10.4.6 Welding electrodes Except as permitted by Clause 10.23.4.5, welding electrodes, electrode/gas, or electrode/flux combinations shall be low hydrogen (i.e., a level of H16 or less) and shall comply with CSA W47.1, CAN/CSA-W48, and CSA W59.



10.4.7 Stud shear connectors Material requirements for stud shear connectors and the qualification of the shear connector base shall comply with CSA W59, Appendix H. Only studs of Type B shall be used.

10.4.8 Cables 10.4.8.1 Bright wire Bright wire shall comply with ASTM A 510.

10.4.8.2 Galvanized wire Galvanized wire shall comply with ASTM A 641/A 641M.

10.4.8.3 Bridge strand and wire rope Bridge strand shall comply with ASTM A 586. Wire rope shall comply with ASTM A 603. 

10.4.9 High-strength bars High-strength bars shall be used only with the approval of the Regulatory Authority and shall comply with ASTM A 722/A 722M. The Engineer shall specify specific notch toughness requirements based on the intended use.

10.4.10 Galvanizing and metallizing Galvanizing shall comply with CAN/CSA-G164 and CSA G189. Zinc metallizing shall comply with CSA G189.

10.4.11 Identification 10.4.11.1 Identified steels The specifications of the materials and products used, including type or grade if applicable, shall be identified by (a) mill test certificates or manufacturer’s certificates satisfactorily correlated to the materials or products to which they pertain; or (b) legible markings on the material or product made by the manufacturer in accordance with the applicable material or product standard. Otherwise, Clause 10.4.11.2 shall apply.

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May 2010 (Replaces p. 438, November 2006)

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.4.11.2 Unidentified steels Structural steels not identified as specified in Clause 10.4.11.1 shall not be used unless tested by an Approved testing laboratory in accordance with CSA G40.20/G40.21. The results of such testing, taking into account both mechanical and chemical properties, shall form the basis for classifying the steels as to specification. Once classified, the specified minimum values for steel at the applicable specification grade shall be used for design.

10.4.12 Coefficient of thermal expansion

The coefficient of linear thermal expansion for steel shall be taken as 12 × 10–6/ °C.

10.4.13 Pins and rollers Pins and rollers greater than 175 mm in diameter shall be forged and annealed or forged and normalized. Pins and rollers 175 mm or less in diameter shall be forged and annealed, forged and normalized, or of cold-finished carbon-steel shafting.

10.5 Design theory and assumptions 10.5.1 General Structural members and components shall be proportioned to satisfy the requirements for the ultimate, serviceability, and fatigue limit states.

10.5.2 Ultimate limit states The factored resistances specified in this Section shall be equal to or greater than the effect of factored loads specified in Section 3 for all relevant ULS considerations, including strength, rupture, bending, buckling, lateral torsional bucking, sliding, overturning, and uplift.

10.5.3 Serviceability limit states 10.5.3.1 General The SLS considerations shall be those of deflection, yielding, slipping of bolted joints, and vibration.

10.5.3.2 Deflection The requirements of Clause 10.16.4 and Section 3 shall apply.

10.5.3.3 Yielding Members of all classes of sections shall be proportioned so that general yielding does not occur. Localized limited yielding shall be permitted.

10.5.3.4 Slipping of bolted joints The requirements of Clause 10.18 shall apply.

10.5.3.5 Vibration The requirements of Section 3 shall apply.

10.5.3.6 Transportability The Engineer shall consider transportability for components of unusual geometry, weight, or dimensions.

10.5.4 Fatigue limit state The requirements of Clause 10.17 shall apply.

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S6S2-11

© Canadian Standards Association

10.5.5 Fracture control The requirements of Clause 10.23 shall apply.

10.5.6 Seismic requirements The requirements of Clause 4.8 shall apply.

10.5.7 Resistance factors



Resistance factors shall be taken as follows: (a) flexure:  s = 0.95; (b) shear:  s = 0.95; (c) compression:  s = 0.90; (d) tension:  s = 0.95; (e) torsion:  s = 0.90; (f) tension in cables:  tc = 0.55; (g) reinforcing steel in composite construction:  r = 0.90; (h) concrete in composite construction:  c as specified in Section 8; (i) bolts:  b = 0.80; (j) load bearing in bolted connections:  br = 0.80; (k) welds:  w = 0.67; (l) shear connectors:  sc = 0.85; (m) beam web bearing, interior:  bi = 0.80; (n) beam web bearing, end:  be = 0.75; and (o) block shear:  u = 0.75

10.5.8 Analysis Unless other methods are Approved, the methods of analysis used shall be as specified in this Section and Section 5. The design of supporting members shall provide for the effect of any significant moment or eccentricity arising from the manner in which a beam, girder, or truss is connected or supported.

10.5.9 Design lengths of members 10.5.9.1 Span lengths Span lengths shall be taken as the distance between centres of bearings or other points of support.

10.5.9.2 Compression members 10.5.9.2.1 General The design of a compression member shall be based on its effective length, KL. The unbraced length, L, shall be taken as the length of the compression member measured centre-to-centre of restraints. The unbraced length may differ for different cross-sectional axes of a member. For the bottom level of a multi-level bent or for a single-level bent, L shall be measured from the top of the base plate. The effective length factor, K, shall be as specified in Clauses 10.5.9.2.2, 10.5.9.2.3, or 10.5.9.2.4, depending on the potential failure modes and whether failure is by buckling or in-plane bending.

10.5.9.2.2 Failure modes involving in-plane bending The effective length shall be taken as the actual unbraced length, i.e., K = 1.0, for beam-columns that would fail by in-plane bending, but only if, when applicable, the sway effects have been included in the analysis of the structure to determine the end moments and forces acting on the beam-columns.

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October 2011 (Replaces p. 440, May 2010)

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.5.9.2.3 Failure modes involving buckling The effective length for axially loaded columns that would fail by buckling and for beam-columns that would fail by out-of-plane lateral torsional buckling shall be based on the rotational and translational restraint afforded at the ends of the unbraced length. 

10.5.9.2.4 Compression members in trusses The effective length for members that would fail by in-plane bending shall be taken as the actual unbraced length, i.e., K = 1.0. The effective length for members that would fail by buckling shall be based on the rotational and translational restraint afforded at the ends of the unbraced length. For half-through or pony-truss spans, the buckling load of the compression chord shall be determined in accordance with Clause 10.14.3.6.

10.6 Durability 10.6.1 General The requirements of Clauses 10.6.2 to 10.6.7 shall apply unless superseded by the requirements of the Regulatory Authority.

10.6.2 Corrosion as a deterioration mechanism The deterioration mechanisms considered for steel components shall include corrosion.

10.6.3 Corrosion protection Corrosion protection shall be provided by alloying elements in the steel, protective coatings, or other Approved means. The type and degree of corrosion protection to be provided shall be shown on the Plans.

10.6.4 Superstructure components 10.6.4.1 General The minimum corrosion protection shall be as specified in Table 10.1 for the applicable superstructure component and environmental exposure condition. 

10.6.4.2 Structural steel Structural steel, including diaphragms and bracing but excluding surfaces in contact with concrete and the contact surfaces of bolted joints, shall be coated with an Approved coating system for a minimum distance of 3000 mm from the ends of girders at expansion joints. Surfaces of girders that are subject to water runoff from the deck shall either be coated with an Approved coating system or the cross-sections shall be increased to account for the estimated loss of section over the design life of the structure.

10.6.4.3 Cables, ropes, and strands All wires in the cables of suspension bridges and the stay cables of cable-stayed bridges shall be hot-dip galvanized. Suspension bridge and arch bridge hangers and other ropes or strands shall be hot-dip galvanized. The completed main cables of suspension bridges shall also be treated with zinc dust paste and wrapped with soft-annealed galvanized wire. The stay cables of cable-stayed bridges shall also be encased in a tube or sheath filled with an Approved grease or wax.

May 2010 (Replaces p. 441, November 2006)

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S6S1-10

© Canadian Standards Association

10.6.4.4 High-strength bars When not sheathed and grouted, high-strength bars shall be hot-dip galvanized.

10.6.4.5 Steel decks In marine environments and in areas where roadways are likely to be salted for winter maintenance, steel decks, except for open grid decks, shall be waterproofed and provided with a skid-resistant wearing surface.

10.6.5 Other components The minimum protective measures for steel components not covered by Clauses 10.6.4.2 to 10.6.4.5 other than superstructure components shall be as specified in Table 10.2 for the applicable environmental exposure condition. Stainless steel inserts in submerged members shall be electrically connected to the reinforcement.

442

May 2010 (Replaces p. 442, November 2006)

(See Clause 10.6.4.1.) Environmental exposure condition No direct chlorides

Air-borne chlorides or light industrial atmosphere

Heavy industrial atmosphere

Dry, rarely wet

Cyclical wet/dry

Wet, Dry, rarely dry rarely wet

Cyclical wet/dry

Wet, Dry, rarely dry rarely wet

Cyclical wet/dry

All superstructures (minimum)

Coat

Uncoated weathering steel

Uncoated weathering steel

Coat

Uncoated weathering steel

Uncoated weathering steel

Coat

Investigate

Investigate Coat

Structure with clearance of less than 3 m over stagnant water or less than 1.5 m over fresh water

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Structure over depressed roadways with tunnel effect

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Open grid decks

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Structure supporting open grid decks

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Faying surfaces of joints

—

—

—

—

—

—

—

—

—

—

Cables, ropes, and strands (see also Clause 10.6.4.3)

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Marine

442A

Supplement No. 1 CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Wet, rarely dry

Component

© Canadian Standards Association

May 2010

Table 10.1 Corrosion protection for superstructure components

(See Clause 10.6.5.) Environmental exposure condition No direct chlorides

Air-borne chlorides or light industrial atmosphere

Heavy industrial atmosphere

In fresh water

Investigate site conditions

Coated

Uncoated Uncoated

Coat or increase section thickness

Coat or increase section thickness

Coat or increase section thickness

Uncoated Uncoated

Investigate site conditions

Investigate site conditions

Investigate site conditions

Investigate site conditions

—

—

Galvanize

Galvanize

Galvanize

Galvanize

—

—

Galvanize Galvanize Galvanize or metallize or metallize or metallize

Galvanize Galvanize — Galvanize Galvanize or metallize or metallize or metallize or metallize

—

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Galvanize, metallize, or coat

—

—

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

Coat

—

—

Moving Grease components or rockers, roller bearings, and pins

Grease

Grease

Grease

Grease

Grease

Grease

Grease

Grease

Grease

—

—

Railings

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

—

—

Utility supports and hardware

Galvanize or Galvanize or Galvanize or epoxy coat epoxy coat epoxy coat

Galvanize or Galvanize or Galvanize or epoxy coat epoxy coat epoxy coat

Galvanize or Galvanize or Galvanize or Galvanize or — epoxy coat epoxy coat epoxy coat epoxy coat

—

Galvanize

Galvanize

Component

Dry, rarely wet

Cyclical wet/dry

Wet, rarely dry

Dry, rarely wet

Cyclical wet/dry

Wet, rarely dry

Dry, rarely wet

Cyclical wet/dry

Substructures

Coat

Uncoated weathering steel

Uncoated weathering steel

Coat

Uncoated weathering steel

Uncoated weathering steel

Coated

Investigate site conditions

Sheet piling

Coat or increase section thickness

Uncoated

Coat or increase section thickness

Coat or increase section thickness

Uncoated

Coat or increase section thickness

Coat or increase section thickness

Light poles, luminaires, Galvanize and sign support structures

Uncoated weathering steel

Galvanize

Galvanize

Galvanize

Galvanize

Deck drains

Galvanize

Uncoated weathering steel

Uncoated weathering steel

Galvanize

Galvanize

Galvanize

Expansion joints

Galvanize Galvanize or metallize or metallize

Galvanize or metallize

Bearings (excluding stainless steel and faying surfaces)

Galvanize, metallize, or coat

Galvanize, metallize, or coat

Faying surfaces of bearing assemblies (excluding stainless steel and Teflon® )

Coat

443

Components of Galvanize mechanically stabilized earth structures, bin walls, and gabions

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

Galvanize

In groundwater

Galvanize Galvanize

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Marine or de-icing runoff

Wet, rarely dry

© Canadian Standards Association

October 2011 (Replaces p. 443, May 2011)

Table 10.2 Corrosion protection for other components

S6S2-11

© Canadian Standards Association

10.6.6 Areas inaccessible after erection Areas inaccessible after erection shall be marked in the Plans and shall be given an Approved protective coating before erection. The inside surfaces of sealed hollow structural sections and sealed orthotropic deck ribs need not be protected.

10.6.7 Detailing for durability 10.6.7.1 Drip bars Drip bars shall be secured to the bottom flanges of plate girders near expansion joints.

10.6.7.2 Interior bracing Interior bracing shall be detailed to allow access for inspection and maintenance over the full length of the bridge.

10.6.7.3 Angles and tees Angles and tees exposed to the environment shall be placed with their vertical legs or webs extending downward wherever practical.

10.6.7.4 End floor beams and end diaphragms End floor beams and end diaphragms under expansion joints shall be arranged to permit coating and future maintenance of surfaces that are exposed to surface runoff. The end diaphragms of box girders shall be detailed to prevent ingress of water into the boxes.

10.6.7.5 Overpasses Girder sections of overpasses over expressways and over urban streets with traffic speed limits greater than 70 km/h shall be detailed to minimize the detrimental effects of salt spray.

10.6.7.6 Pockets and depressions Pockets and depressions that could retain water shall be avoided, provided with effective drainage, or filled with water-repellent material.

10.7 Design details 10.7.1 General Members and connections shall be detailed to minimize their susceptibility to corrosion, fatigue, brittle fracture, and lamellar tearing. 

10.7.2 Minimum thickness of steel The minimum thickness of steel shall be as follows: (a) gusset plates for main members and all material in end floor beams and end diaphragms and their connections: 9.5 mm; (b) closed sections, e.g., tubular members or closed ribs in orthotropic decks that are sealed against entry of moisture: 6 mm; (c) webs of rolled shapes: 6 mm; (d) webs of plate girders and box girders: 9.5 mm; and (e) other structural steel except for fillers, railings, and components not intended to resist loads: 8 mm.

444

October 2011 (Replaces p. 444, May 2010)

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.7.3 Floor beams and diaphragms at piers and abutments Floor beams and diaphragms at piers and abutments shall be designed to facilitate jacking of the superstructure unless the main longitudinal members are designed to be jacked directly.

10.7.4 Camber 10.7.4.1 Design Girders with spans 25 m long or longer shall be cambered to compensate at least for dead load deflections and to suit the highway profile grade. For composite beams, an allowance shall also be made for the effects of creep and shrinkage of the concrete. The Plans shall show (a) the deflection of the girders due to the dead load of the steel alone; and (b) the deflection due to the full dead load, including that of the steel, slab, barriers, sidewalks, and wearing surface. For spans shorter than 25 m, the deflections and the profile of the concrete deck slab over the beams may be accommodated by increasing the slab thickness over the beams in lieu of providing a camber, if specified on the Plans.

10.7.4.2 Fabrication Shop drawings shall show the total camber diagram to be used as a web cutting profile. The camber diagram shall include compensation for the deflection due to full dead load, an allowance for fabrication and welding distortion, and an allowance (if applicable) for the vertical alignment of the highway. 

10.7.4.3 Horizontally heat-curved rolled or welded beams For rolled beams and welded I-section plate girders that are heat curved to obtain a horizontal curvature, additional camber shall be added to compensate for the non-recoverable vertical deflection that occurs during construction and in service. The total camber shall be calculated as

⎛ D + DSDL ⎞ D = ⎜ DL ⎟⎠ [ Dm + Dr ] Dm ⎝ where

Dr =

0.02L2Fy ⎡ 305 000 − R ⎤ ⎛ y s + y c ⎞ ⎥⎜ ⎢ ⎟ ≥0 Es ⎣ 260 000 ⎦ ⎝ 2y s y c ⎠

where

 DL

= specified camber at any section, mm

SDL

= camber at any point along length L, to compensate for deflection due to dead loads on the composite section (if applicable), mm

m r

= maximum value of DL + SDL within length L, mm

L

= span length for simple spans, mm

= camber at any point along length L, to compensate for deflection due to dead loads on the steel section only, mm

= additional camber, mm = distance between the points of dead load contraflexure for continuous spans (see Figure A5.1.1), mm

Fy

= specified minimum yield stress of flanges, MPa

Es

= modulus of elasticity of steel, MPa

R

= horizontal radius of curvature, mm

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ys

= distance from the neutral axis to the extreme outer fibre of the steel section (maximum distance for non-symmetrical sections), mm

yc

= maximum distance from the neutral axis to the extreme outer fibre of the composite section (if applicable), mm

10.7.5 Welded attachments All attachments to primary tension and fracture-critical members, including transverse and longitudinal stiffeners, shall be connected by continuous welds. Longitudinal stiffeners shall be spliced by complete joint penetration groove welds.

10.8 Tension members 10.8.1 General 10.8.1.1 Proportioning Tension members shall be proportioned on the basis of their gross and effective net cross-sectional areas and an examination of block tearout of the material. In cases where not all portions of a cross-section are directly connected to the adjoining elements, an effective net area shall be calculated as an allowance for shear lag.

10.8.1.2 Slenderness The slenderness ratio of a tension member shall not exceed 200 unless otherwise Approved.

10.8.1.3 Cross-sectional areas 

10.8.1.3.1 General The gross and net cross-sectional areas to be used in calculating the resistance of a tension member shall be as follows: (a) The gross cross-sectional area, Ag , shall be the sum of the products of the thickness times the gross width of each element in the cross-section, measured perpendicular to the longitudinal axis of the member. (b) The net cross-sectional area, An , shall be determined by summing the net areas of each segment along a potential path of minimum resistance, calculated as follows: (i) An = wnt for any segment normal to the force (i.e., in direct tension); (ii) An = wnt + s 2t / 4g for any segment inclined to the force where wn = net width = gross width – sum of hole diameters in the gross width Deductions for fastener holes shall be made using a hole diameter 2 mm greater than the specified hole diameter for punched holes. This allowance shall be waived for drilled holes or holes that are subpunched and reamed to the specified hole diameter.

10.8.1.3.2 Effective net area accounting for shear lag effects In general, each portion of the cross-section of a tension member shall be connected at its ends with sufficient fasteners (bolts or welds) to transmit the load attributable to the portion being connected. Where this is not practicable, an effective net area shall be calculated as

x⎞ ⎛ Ane = An ⎜ 1 − ⎟ ⎝ L⎠

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

where x = distance perpendicular to axis of member from the fastener plane to the centroid of the portion of the area of the cross-section under consideration. In the absence of a more precise method, the effective net area for shear lag shall be established as described in Clauses 10.8.1.3.2.1 to 10.8.1.3.2.5. 

10.8.1.3.2.1 Bolted tension elements When fasteners transmit load to each of the cross-sectional elements of a member in tension in proportion to their respective areas, the effective net area is equal to the net area, i.e., Ane = An. When bolts transmit load to some, but not all, of the cross-sectional elements and when the critical net area includes the net area of unconnected elements, the effective net area shall be taken as follows: (a) for WWF, W, M, or S shapes with flange widths at least two-thirds the depth and for structural tees cut from those shapes, when only the flanges are connected with three or more transverse lines of fasteners: Ane = 0.90An ; (b) for angles connected by only one leg with (i) four or more transverse lines of fasteners: Ane = 0.80An ; and (ii) fewer than four transverse lines of fasteners: Ane = 0.60An ; and (c) for all other structural shapes connected with (i) three or more transverse lines of fasteners: Ane = 0.85An ; and (ii) with two transverse lines of fasteners: Ane = 0.75An .



10.8.1.3.2.2 Welded tension elements When a tension load is transmitted by welds, the effective net area shall be computed as Ane = An1 + An2 + An3 where An1, An2, An3 = net areas of the connected plate elements subject to one of the following methods of load transfer: (a) for elements connected by transverse welds, An1: An1 = wt (b) for elements connected by longitudinal welds along two parallel edges, An2 : (i) when L 2w: An2 = 1.00 wt (ii) when 2w > L  w: An2 = 0.50 wt + 0.25 Lt (iii) when w > L: An2 = 0.75 Lt where L

= average length of welds on the two edges, mm

w = plate width (distance between welds), mm (c) for elements connected by a single longitudinal weld, An3: (i) when L  w:

x⎞ ⎛ An3 = ⎜ 1 − ⎟ wt ⎝ L⎠ (ii) when w > L: An3 = 0.50 Lt

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where x = eccentricity of the weld with respect to the centroid of the connected element, mm L

= length of weld in the direction of the loading, mm

The outstanding leg of an angle is considered connected by the (single) line of weld along the heel. 

10.8.1.3.2.3 Rational analysis Larger values of the effective net area may be used if justified by tests or rational analysis.



10.8.1.3.2.4 Block shear — Tension member, beam, and plate connections The factored resistance for a potential failure involving the simultaneous development of tensile and shear component areas shall be taken as follows:

Tr = fu ⎡⎣Ut AnFu + 0.6Agv Fm ⎤⎦ where Ut

= efficiency factor = 1.0 when the failure pattern is symmetrical and the load concentric with the block. Otherwise, Ut is obtained from the following Table for specific applications. Connection type

Ut

Flange connected tees

1.0

Angles connected by one leg and stem connected tees

0.6

Coped beams — one bolt line

0.9

Coped beams — two bolt lines

0.3

An is the net area in tension as defined in Clause 10.8.1.3.1 and Agv is the gross area in shear, taken as the sum of the products of the thickness times the gross length of each segment of the block shear failure surface parallel to the applied force.

Fm =

(F

y

+ Fu 2

)

for Fy < 485 MPa, otherwise, Fm = Fy

Note: The term 0.6AgvFm in the above equation for Tr may be used to predict bolt tear out capacity along two parallel planes adjacent to the bolt hole.



10.8.1.3.2.5 Angles For angles, the gross width shall be the sum of the widths of the legs minus the thickness. The gauge for holes in opposite legs shall be the sum of the gauges from the heel of the angle minus the thickness.

10.8.1.4 Pin-connected members in tension In pin-connected members in tension, the net area, An , across the pin hole and normal to the axis of the member shall be at least 1.33 times the cross-sectional area of the body of the member. The net area beyond the pin hole of any section on either side of the axis of the member, measured at an angle of 45° or less to the axis of the member, shall be not less than 0.9 times the cross-sectional area of the member. The distance from the edge of the pin hole to the edge of the member, measured transverse to the axis of the member, shall not exceed four times the thickness of the material at the pin hole. The diameter of a pin hole shall be not more than 1 mm larger than the diameter of the pin.

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.8.2 Axial tensile resistance The factored tensile resistance, Tr , shall be taken as the least of (a) s AgFy ; (b) 0.85s An Fu ; and (c) 0.85s Ane Fu .

10.8.3 Axial tension and bending Members subjected to bending moments and axial tensile forces shall satisfy the following relationship:

Tf Mf + ≤ 1 .0 Tr Mr where Mr

= sMp for Class 1 and 2 sections = sMy for Class 3 sections

Mf Tf Z − ≤ 1.0 for Class 1 and 2 sections Mr Mr A Mf TS − f ≤ 1.0 for Class 3 sections Mr Mr A Note: Section classes are specified in Clause 10.9.2.1. Mr is specified in Clause 10.10.2 for Class 1 and 2 sections and in Clause 10.10.3 for Class 3 sections.

10.8.4 Tensile resistance of cables The factored axial tensile resistance, Tr , shall be taken as Tr =  tcTu

10.9 Compression members 10.9.1 General 10.9.1.1 Cross-sectional area Compression members shall be proportioned based on the gross area of the cross-section calculated by summing the products of the thickness and gross width of each element taken normal to the axis of the member.

10.9.1.2 Method of calculation Provided that the requirements of Table 10.3 are met, the expressions for compressive resistance in Clause 10.9.3 shall apply. Flexural buckling with respect to the principal axes of the cross-section and torsional or flexural-torsional buckling shall be considered. Methods for calculating the compressive resistance of members, other than those specified in Clause 10.9.3, shall require Approval.

10.9.1.3 Slenderness The slenderness ratio shall not exceed 120 for main compression members or 160 for secondary and bracing members.

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10.9.2 Width-to-thickness ratio of elements in compression 10.9.2.1 General Structural sections shall be designated as Class 1, 2, 3, or 4 depending on the width-to-thickness ratio of the elements that make up the cross-section and on the conditions of loading. A Class 1 section is one that will attain the plastic moment capacity, adjusted for the presence of axial force if necessary, and permit subsequent redistribution of bending moment. A Class 2 section is one that will attain the plastic moment capacity, adjusted for the presence of axial force if necessary, but not necessarily permit subsequent moment redistribution. A Class 3 section is one that will attain the yield moment capacity, adjusted for the presence of axial force if necessary. A Class 4 section is one in which the slenderness of the elements making up the cross-section exceeds the limits of Class 3. The capacity of a Class 4 section shall be treated on a case-by-case basis in accordance with this Code. The width-to-thickness ratios of elements subject to compression shall not exceed the limits specified in Table 10.3.

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May 2010 (Replaces p. 448, November 2006)

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© Canadian Standards Association



Table 10.3 Width-to-thickness ratio of elements in compression (See Clauses 10.9.1.2, 10.9.2.1, 10.10.2.1, and 10.10.3.1.) Description of element

Class 1

Class 2

Class 3‡

Legs of angles and elements supported along one edge, except as covered elsewhere in this Table

—

—

b/t  200/ ( Fy )

Angles in continuous contact with other elements; plate girder stiffeners

—

—

b/t  200/ ( Fy )

Stems of T-sections

b/t  145/ ( Fy ) *

b/t  170/ ( Fy ) *

b/t  340/ ( Fy )

Flanges of I- or T-sections; plates projecting from compression elements; outstanding legs of pairs of angles in continuous contact†

b/t  145/ ( Fy )

b/t  170/ ( Fy )

b/t  200/ ( Fy )

Flanges of channels

—

—

b/t  200/ ( Fy )

Flanges of rectangular hollow structural shapes

b/t  420/ ( Fy )

b/t  525/ ( Fy )

b/t  670/ ( Fy )

Flanges of box girder sections; flange cover plates and diaphragm plates between lines of fasteners or welds

b/t  525/ ( Fy )

b/t  525/ ( Fy )

b/t  670/ ( Fy )

Perforated cover plates

—

—

b/t  840/ ( Fy )

Webs in axial compression

h/w  670/ ( Fy )

h/w  670/ ( Fy )

h/w  670/ ( Fy )

Webs in flexural compression

h/w  1100/ ( Fy )

h/w  1700/ ( Fy )

h/w  1900/ ( Fy )

Webs in combined flexural and axial compression

C ⎤ h 1100 ⎡ ≤ ⎢1 − 0.39 f ⎥ w C y ⎥⎦ Fy ⎢⎣

C ⎤ h 1700 ⎡ ≤ ⎢1− 0.61 f ⎥ w C y ⎥⎦ Fy ⎢⎣

C ⎤ h 1900 ⎡ ≤ ⎢1− 0.65 f ⎥ w C y ⎥⎦ Fy ⎢⎣

Circular and multi-sided hollow sections in axial compression

—

—

D 23 000 ≤ t Fy

Circular and multi-sided hollow sections in flexural compression

D 13 000 ≤ t Fy

D 18 000 ≤ t Fy

D 66 000 ≤ t Fy

*Class 1 and 2 sections subjected to flexure having an axis of symmetry in the plane of loading unless the effects of asymmetry of the section have been included in the analysis. †Can be considered a Class 1 or 2 section, as applicable, only if angles are continuously connected by adequate mechanical fasteners or welds and there is an axis of symmetry in the plane of loading. ‡A Class 4 section is a section that exceeds the limits of a Class 3 section.

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10.9.2.2 Elements supported along one edge For elements supported along only one edge that is parallel to the direction of the compressive force, the width, b, shall be taken as follows: (a) for plates: the distance from the free edge to the line of bolts or welds; (b) for legs of angles, flanges of channels and zees, or stems of tees: the full nominal dimension; and (c) for flanges of I-shapes and tees: one-half of the flange width.

10.9.2.3 Elements supported along two edges For elements supported along two edges that are parallel to the direction of the compressive force, the width, b or h, as applicable, shall be taken as follows: (a) for flange or diaphragm plates in built-up sections, b shall be taken as the distance between adjacent lines of bolts or lines of welds; (b) for the sides of rectangular hollow structural sections, b or h shall be taken as the clear distance between edge-supporting elements less two wall thicknesses; (c) for webs of built-up sections, h shall be taken as the distance between the nearest lines of bolts connecting either edge of the web or as the clear distance between flanges when welds are used; and (d) for webs of rolled sections, h shall be taken as the clear distance between flanges.

10.9.2.4 Thickness In all cases, the thickness of elements shall be taken as the nominal thickness. For tapered flanges, the thickness shall be taken as that at the midpoint of the element.

10.9.2.5 Multi-sided hollow sections For multi-sided hollow sections that approximate a circle, D shall be taken as the diameter of the circle that inscribes the outside of the midpoint of the flats of the section.

10.9.3 Axial compressive resistance 

10.9.3.1 Flexural buckling The factored axial compressive resistance, Cr , of a member conforming to the limitations specified in Clauses 10.9.1 and 10.9.2 shall be taken as Cr =  s AFy (1 + 2n )–1/n where

KL Fy r π2E s



=

n

= 1.34, except for welded H-shapes with flame-cut flange edges and hollow structural sections manufactured in accordance with CSA G40.20, Class H (i.e., hot-formed or cold-formed stress-relieved sections), where n = 2.24

10.9.3.2 Torsional or flexural-torsional buckling The torsional or flexural-torsional buckling resistance of asymmetric, singly symmetric, and cruciform sections shall be calculated by using n = 1.34 and replacing  in Clause 10.9.3.1 by e , as follows:

le = Fy / Fe

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

where (a) for cruciform sections, the critical torsional elastic buckling stress, Fe , is

⎡ π2E sCw ⎤ 1 Fe = ⎢ + Gs J ⎥ 2 ⎢⎣ (K z L ) ⎥⎦ (I x + Iy ) (b) for sections singly symmetric about the y-axis, the critical flexural-torsional elastic buckling stress, Fe , is Fey + Fez ⎡ 4Fey Fez H ⎤ ⎢1− 1− ⎥ 2H ⎢ (Fey + Fez )2 ⎥ ⎣ ⎦ (c) for asymmetric sections, the critical flexural-torsional elastic buckling stress, Fe , is the lowest root of Fe =

(Fe – Fex)(Fe – Fey)(Fe – Fez) – Fe2(Fe – Fey)(x0 /r0)2 – Fe2(Fe – Fex)(y0 /r0)2 = 0 and Fex and Fey are calculated with respect to the principal axes where Kz

= the effective length factor for torsional buckling, taken as 1.0 unless a lesser value is established by rigorous analysis

Fey

=

Fez

⎡ π2E sCw ⎤ = ⎢ + Gs J ⎥ / Ar02 2 ⎢⎣ (K z L ) ⎥⎦

H

= 1 – y 02 / r02 for sections singly symmetric about the y -axis

Fex

=

π2E s (K y L / ry )2

π2E s (K x L / rx )2

x 0, y 0 = the coordinates of the shear centre of the section with respect to the centroid r 02

= y 02 + rx2 + ry2 for sections singly symmetric about the y -axis = x 02 + y 02 + rx2 + ry2 for asymmetric sections

10.9.4 Axial compression and bending 10.9.4.1 Cross-sectional and member strengths — All classes of sections  except Class 1 sections of I-shaped members Members subject to coincident bending and axial compressive force shall be proportioned so that

Cf U1x Mfx U1y Mfy + + ≤ 1 .0 Cr Mrx Mry where



U1x

= the value as specified in Clause 10.9.4.2, but not less than 1.0

U1y

= the value as specified in Clause 10.9.4.2

The resistance of the member shall be determined by taking the following into consideration: (a) Cross-sectional strength, for which Cr =  s AFy ; Mrx and Mry are defined by Mr in Clauses 10.10.2.2 and 10.10.2.4 for Class 2 sections and Clauses 10.10.3.2 and 10.10.3.5 for Class 3 sections, with respect to the x-axis and y-axis, respectively; and U1x and U1y are taken as 1.0. (b) Overall member strength, for which Cr is as specified in Clause 10.9.3.1 and is based on the maximum slenderness ratio for biaxial bending. For uniaxial strong axis bending, Cr = Crx . Mrx and Mry are as specified in Item (a) and U1x and U1y are as specified in Clause 10.9.4.2. October 2011 (Replaces p. 451, November 2006)

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(c) Lateral torsional buckling strength, for which Cr is as specified in Clause 10.9.3 and is based on weak axis, torsional, or flexural-torsional buckling, as appropriate. Mrx is as specified in Clause 10.10.2.3 for Class 2 sections and Clause 10.10.3.3 for Class 3 sections. Mry is as specified in Clause 10.10.2.4 for Class 2 sections and Clause 10.10.3.5 for Class 3 sections. Note: Item (c) does not apply to members with a closed cross-section because these members do not generally fail by lateral torsional buckling.

10.9.4.2 Values of U1

In lieu of a more detailed analysis, the value of U1 accounting for the second-order effects due to the deformation of a member between its ends shall be taken as

(a) U1x =

(b) U1y =

w1x C 1− f C ex w1y C 1− f C ey

where

1

= the value specified in Clause 10.9.4.3

Ce

= the Euler buckling load

10.9.4.3 Values of  1

Unless otherwise determined by analysis, the following values shall be used for 1: (a) for members not subject to transverse loads between supports: 0.6 – 0.4  0.4; (b) for members subject to distributed loads or a series of point loads between supports: 1.0; and (c) for members subject to a concentrated load or moment between supports: 0.85.

10.9.4.4 Member strength and stability — Class 1 sections of I-shaped members Members required to resist coincident bending moments and an axial compressive force shall be proportioned so that

Cf 0.85U1x Mfx 0.60U1y Mfy + + ≤ 1. 0 Cr Mrx Mry where all of the terms in this expression are as specified in Clauses 10.9.4.1, 10.9.4.2, 10.10.2.2, and 10.10.2.3. The resistance of the member shall be calculated for (a) cross-sectional strength; (b) overall member strength; and (c) lateral torsional buckling strength. In addition, the member shall meet the following requirement: Mfx Mfy + ≤ 1 .0 Mrx Mry where Mrx and Mry are as specified in Clause 10.10.2.2 or 10.10.2.3, as applicable.

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.9.5 Composite columns 10.9.5.1 General The requirements of Clause 10.9.5 shall apply to composite columns consisting of steel hollow structural sections completely filled with concrete. The type of concrete, its strength, and its other properties shall comply with Section 8.

10.9.5.2 Application Hollow structural sections designated as Class 1, 2, or 3 sections shall be assumed to carry compressive load as composite columns. Class 4 hollow structural sections that are completely filled with concrete and are designed as composite columns shall have, for walls of rectangular sections, width-to-thickness ratios that do not exceed 1350/ Fy , and for circular sections, outside diameter-to-thickness ratios of circular sections that do not exceed 28 000/Fy .

10.9.5.3 Axial load on concrete The axial load assumed to be carried by the concrete at the top level of a column shall be only that portion applied by direct bearing on the concrete. A base plate or similar means shall be provided for load transfer at the bottom.

10.9.5.4 Compressive resistance The factored compressive resistance of a composite column, Crc , shall be taken as Crc =  Cr +  ‘Cr‘ where Cr

= the value specified in Clause 10.9.3.1

C r‘

=

0.85fc fc′Ac lc−2 ⎡ 1+ 0.25lc−4 − 0.5lc−2 ⎤ ⎣⎢ ⎦⎥

c

=

KL rc

Ec

= initial elastic modulus for concrete, taking into consideration the effects of long-term loading for normal weight concrete, with f c‘ expressed in megapascals

where

fc′ p 2Ec

2500(1+ S /T ) fc′ where S = short-term oad l T = total load on the column =

 ’ = 1.0; except for circular hollow sections with a height-to-diameter ratio (L/D) of less than 25, for which

1

t =

1+ r + r 2

and

⎡ 25r 2t ⎤ ⎡ Fy ⎤ t ′ = 1+ ⎢ ⎥⎢ ⎥ ⎣ D / t ⎦ ⎣ 0.85fc′ ⎦ where

 = 0.02 (25 – L/D) October 2011 (Replaces p. 453, May 2010)

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10.9.5.5 Bending resistance The factored bending resistance, Mr c , of a composite concrete-filled hollow structural section shall be taken as Mr c = Cr e + Cr‘e‘ where (a) for a rectangular hollow structural section: Cr

=

C r‘

=

Cr + Cr‘

= =

fs As Fy − C r′ 2 c a(b – 2t) fc’ Tr sAst Fy

Note: The concrete in compression is taken to have a rectangular stress block of intensity fc’ over a depth of a = 0.85c, where c is the depth of concrete in compression.

(b) for a circular hollow structural section:

Dt 2

Cr

=

fs Fy b

e

=

⎡ 1 1⎤ bc ⎢ + ⎥ ⎣ ( 2p − b ) b ⎦

C r‘

=

⎡ b D 2 bc fc fc′ ⎢ – 2 ⎣ 8

e‘

=

⎡ ⎤ bc2 1 bc ⎢ + ⎥ 2 ⎢⎣ ( 2p - b ) 1.5b D − 6bc ( 0.5D − a ) ⎥⎦

⎡D ⎤⎤ ⎢⎣ 2 – a ⎥⎦ ⎥ ⎦

where

 = value in radians derived from the following recursive equation: b=

fs As Fy + 0.25fc D 2fc′ ⎡⎣ sin ( b / 2 ) − sin2 ( b / 2 ) tan ( b / 4 ) ⎤⎦ 0.125fc D 2fc′ + fs DtFy

bc = D sin(/2) a

= bc /2 tan(/4)

Conservatively, Mr c may be taken as 

(

)

Mr c = Z − 2thn2 fs Fy + ⎡(2 / 3) (0.5D − t )3 − (0.5D − t ) hn2 ⎤ fc fc′ ⎣ ⎦ where hn = Z

454

fc Ac fc′

(

2Dfc fc′ + 4t 2fc Fy − fc fc′

)

= plastic modulus of the steel section alone

October 2011 (Replaces p. 454, May 2010)

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.9.5.6 Axial compression and bending resistance Members required to resist both bending moments and axial compression shall be proportioned analogously with Clause 10.9.4 so that

Cf + C rc

Bw1Mf ≤ 1.0 ⎡ Cf ⎤ Mrc ⎢1− ⎥ ⎣ C ec ⎦

Mf ≤ 1.0 Mrc B=

C rco − C rcm C rco where Crco Crcm = Mrc

= factored compressive resistance with  = 0 factored compressive resistance that can coexist with Mrc = the value specified in Clause 10.9.5.5

Conservatively, B may be taken as equal to 1.0.

10.10 Beams and girders 10.10.1 General 10.10.1.1 Cross-sectional area Beams and girders shall be proportioned on the basis of the geometric properties of the gross section, except that a deduction shall be made for the area of the bolt holes exceeding 15% of the gross flange area.

10.10.1.2 Flange cover plate restrictions Flanges of welded beams or girders shall consist of single plates or a series of plates, joined end-to-end by complete penetration groove welds. The use of welded partial-length cover plates shall require Approval.

10.10.1.3 Lateral support Lateral support of compression flanges shall be provided by adequate connection to the deck or by bracing capable of restraining lateral displacement and twisting of the beams and girders unless it can be demonstrated that such restraint is developed between the steel beam and the concrete slab. Wood decks shall not be considered to provide lateral support unless the deck and fastenings are designed for this purpose.

10.10.1.4 Flange-to-web connections Welds connecting flanges to webs shall be proportioned to resist interface shear due to bending combined with any loads that could be transmitted from the flange to the web other than by direct bearing.

10.10.2 Class 1 and 2 sections 10.10.2.1 Width-to-thickness ratios Class 1 and 2 sections subject to flexure and having an axis of symmetry in the plane of loading shall meet the requirements of Clause 10.9.2. For calculating the limiting width-to-thickness ratios of the web of monosymmetric sections, h in Table 10.3 shall be replaced by 2dc .

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10.10.2.2 Laterally supported members When continuous lateral support is provided to the compression flange of a member subjected to bending about its major axis, the factored moment resistance, Mr , shall be calculated as Mr =  s Zx Fy =  sMpx

10.10.2.3 Laterally unbraced members For a section subjected to bending about its major axis and laterally unbraced over a length, L, the factored moment resistance, Mr , shall be calculated as (a)

⎡ 0.28Mp ⎤ Mr = 1.15fsMp ⎢1− ⎥ ≤ fsMp , when Mu > 0.67Mp ; or Mu ⎦ ⎣

(b) Mr =  s Mu , when Mu  0.67Mp The critical elastic moment, Mu , of a monosymmetric section shall be taken as

Mu =

w2π ⎡ E s Iy Gs J ⎡B1 + 1+ B2 + B12 ⎤ ⎤ ⎢⎣ ⎥⎦ ⎥⎦ L ⎢⎣

where

w2

=

4Mmax 2 Mmax

+ 4Ma2 + 7Mb2 + 4Mc2

≤ 2.5

where 

Mmax = maximum absolute value of factored bending moment in unbraced segment, N•mm Ma

= factored bending moment at one-quarter point of unbraced segment, N•mm

Mb

= factored bending moment at midpoint of unbraced segment, N•mm

Mc

= factored bending moment at three-quarter point of unbraced segment, N•mm

L

= length of unbraced segment of beam, mm

B1

=

π

B2

=

π2E sCw

b x E s Iy 2L Gs J where x = coefficient of monosymmetry L2Gs J

For doubly symmetric sections,

x = 0.0 B1 = 0.0 so that 2

Mu = w 2 π E I G J + ⎡ pE s ⎤ l C s y s ⎢⎣ L ⎥⎦ y w L The general expression for the critical elastic moment and formulas for  x , J, and Cw for I-girder and open-top box girders as specified in Clause C10.10.2.3 of CSA S6.1 may be used for guidance. A more rigorous analysis, taking into account both elastic and inelastic behaviour, may also be used.

10.10.2.4 Bending about the minor axis For a section subjected to bending about its minor axis, whether laterally braced or unbraced, the factored moment resistance, Mr , shall be calculated as Mr =  s Zy Fy =  s Mpy

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10.10.3 Class 3 sections 10.10.3.1 Width-to-thickness ratios Class 3 sections subject to flexure and having an axis of symmetry in the plane of loading shall meet the requirements of Clause 10.9.2. For calculating the limiting width-to-thickness ratios of the web of monosymmetric sections, h in Table 10.3 shall be replaced by 2dc .

10.10.3.2 Laterally supported members When continuous lateral support is provided to the compression flange of a member subject to bending about its major axis, the factored moment resistance, Mr , shall be calculated as Mr = φ sSx Fy = φ sMy

10.10.3.3 Laterally unbraced members For a section subjected to bending about its major axis and laterally unbraced over a length, L, the factored moment resistance , Mr , shall be calculated as

⎡ 0.28My ⎤ Mr = 1.15fs My ⎢1− ⎥ ≤ fs My , when Mu > 0.67My Mu ⎦ ⎣ = φ sMu , when Mu ≤ 0.67My where Mu = the value specified in Clause 10.10.2.3 for doubly symmetric and monosymmetric sections

10.10.3.4 Class 4 sections For beams and girders with continuous lateral support provided to the compression flange, with webs that meet the requirements of Class 3, and whose flanges exceed the slenderness limits of Class 3, the factored moment resistances shall be computed as for a Class 3 section, except that the elastic section modulus, S, shall be replaced by an effective section modulus, Se , determined using (a) an effective flange width of 670t/ Fy for flanges supported along two edges; and (b) an effective projecting flange width of 200t/ Fy for flanges supported along one edge. However, the projecting flange width shall not exceed 30t. Sections with flanges that meet the requirements of Class 3 may have unstiffened Class 4 webs provided that h/w ≤ 150 and the factored moment resistance is reduced by the factor specified in Clause 10.10.4.3. Sections having webs with h/w > 150 shall be designed as stiffened plate girders in accordance with Clause 10.10.4.

10.10.3.5 Bending about the minor axis For a section subjected to bending about its minor axis, whether laterally braced or unbraced, the factored resistance, Mr , shall be calculated as Mr = φ sSy Fy = φsMry

10.10.4 Stiffened plate girders 10.10.4.1 Width-to-thickness ratio of flanges Stiffened plate girders shall have Class 1, 2, or 3 flanges.

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10.10.4.2 Width-to-thickness ratios of webs The width-to-thickness ratios of transversely stiffened webs without longitudinal stiffeners shall meet the requirements of Clause 10.17.2.5. When a longitudinal stiffener is provided in accordance with Clause 10.10.7, the width-to-thickness ratio, h/w, shall not exceed 6000/ Fy .

10.10.4.3 Moment resistance The factored moment resistance shall be determined in accordance with Clause 10.10.3.2 or 10.10.3.3, as applicable. For girders without longitudinal stiffeners where 2dc /w > 1900/ Fy , the moment resistance, calculated for the compression flange, shall be reduced by the following factor:

1−

1 1200Acf 300 + Aw

⎡ 2dc 1900 ⎤ − ⎢ ⎥ Mf /fs S ⎥⎦ ⎢⎣ w

10.10.5 Shear resistance 10.10.5.1 Factored shear resistance The factored shear resistance of the web of a flexural member, Vr , shall be taken as Vr = φ s Aw Fs where Aw , the shear area, is calculated using d for rolled shapes and h for fabricated or manufactured girders, and Fs , the ultimate shear stress, is equal to Fcr + Ft , where Fcr and Ft shall be taken as follows: (a) when :

h k ≤ 502 v w Fy

Fcr = 0.577Fy Ft = 0 (b) when :502

Fcr =

kv h k < ≤ 621 v Fy w Fy

290 Fy kv h /w

⎡ 1 Ft = ⎡0.5Fy − 0.866Fcr ⎤ ⎢ ⎣ ⎦⎢ 2 ⎢⎣ 1+ ( a / h )

⎤ ⎥ ⎥ ⎥⎦

(c) when : h > 621 kv w Fy

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Fcr =

180 000kv

(h / w )2

⎡ 1 Ft = ⎡⎣0.5Fy − 0.866Fcr ⎤⎦ ⎢ ⎢ 2 ⎢⎣ 1+ ( a / h ) where kv

Canadian Highway Bridge Design Code

5.34

=

4+

=

5.34 +

( a / h )2

⎤ ⎥ ⎥ ⎥⎦

when a / h < 1

4

( a / h )2

when a / h ≥ 1

For unstiffened webs, a /h shall be considered infinite, so that kv = 5.34. When used, intermediate transverse stiffeners shall be spaced to suit the shear resistance determined in this Clause, except that at girder end panels and adjacent to large openings in the web, the resistance shall be calculated using Ft = 0 unless means are provided to anchor the tension field.

10.10.5.2 Combined shear and moment When subject to the simultaneous action of shear and moment, transversely stiffened webs that depend on tension field action to carry shear, i.e., with h / w > 502 kv / Fy , shall be proportioned so that (a) Vf ≤ 1.0 ; Vr

Mf ≤ 1.0 ; and Mr

(b)

(c) 0.727 Mf + 0.455 Vf < 1.0 Mr Vr where Vr is determined in accordance with Clause 10.10.5.1 and Mr is determined in accordance with Clause 10.10.2, 10.10.3, or 10.10.4, as applicable.

10.10.6 Intermediate transverse stiffeners 10.10.6.1 General Clause 10.10.6 shall apply to girders with intermediate transverse web stiffeners. For webs that are stiffened both transversely and longitudinally, Clause 10.10.7 shall apply. Web stiffeners are not required when the unstiffened shear resistance, calculated in accordance with Clause 10.10.5.1, exceeds the factored shear and h / w ≤ 150. Transverse stiffeners, when required, shall be provided at a spacing, a, in order to develop the shear capacity. The distance between stiffeners, a, shall not exceed 67 500h / (h / w )2 when h / w is greater than 150 and shall not exceed 3h when h /w is less than or equal to 150.

10.10.6.2 Proportioning transverse stiffeners Intermediate transverse stiffeners provided on one or both sides of the web shall be proportioned so that (a) I ≥ aw3j mm4 where j

= 2.5 (h / a)2 − 2 but is not less than 0.5

I shall be taken about an axis at the mid-plane of the web for stiffener pairs or at the near face of the web for single stiffeners.

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⎡ ⎤ ⎡ ⎤ aw ⎢ a /h ⎥ Vf CD − 18w 2 ⎥ Y ≥ 0 As = ⎢ 1− ⎢ 2 ⎢ ⎥ 2 ⎥ 1+ ( a / h ) ⎥⎦ Vr ⎢⎣ ⎢⎣ ⎥⎦ where Vf / Vr = the larger ratio of the two panels adjacent to the stiffener 310 000kv C = 1− but is not less than 0.10 2 Fy (h / w ) D

= 1.0 for stiffeners provided in pairs = 1.8 for single-angle stiffeners with the attached leg parallel to the web = 2.4 for single-plate stiffeners = 3.0 for single-angle stiffeners with the attached leg perpendicular to the web

The width of a plate used as a stiffener shall not be less than 50 mm plus h /30 and shall not be less than one-quarter of the full width of the flange. The width-to-thickness ratio of intermediate transverse stiffeners shall not exceed 200/ Fy unless the section properties of the stiffeners are deemed to be based on an effective width of 200/ Fy . The projecting stiffener width shall not exceed 30t.

10.10.6.3 Connection to web The connection between the web and the stiffener or stiffeners shall be designed for a shear force of 0.0001hFy1.5 N per mm of web depth, h. When the largest computed ULS shear, Vf , in adjacent panels is less than Vr as calculated in accordance with Clause 10.10.5.1, this requirement may be reduced in the proportion of Vf /Vr , but shall never be less than the value of any concentrated load or reaction required to be transmitted to the web through the stiffener.

10.10.6.4 Stiffener details at flanges The distance between the end of the stiffener weld and the near edge of the web-to-flange fillet weld shall not be less than 4w or more than 6w. Transverse stiffeners need not have a snug fit with the tension flange. However, stiffeners provided on one side of the web shall have at least a snug fit against the compression flange and preferably be attached to it. Stiffeners used as connecting plates for diaphragms, cross-frames, or floor beams shall be connected by welding or bolting to both flanges. The requirements of Clause 10.17.3.2 shall also apply.

10.10.7 Longitudinal web stiffeners 10.10.7.1 General Clause 10.10.7 shall apply to girders with both longitudinal and transverse stiffeners. The spacing, a, of transverse stiffeners of longitudinally stiffened webs shall not exceed 1.5hp , where hp is the maximum subpanel depth. The total web depth, h, shall be used in determining the shear capacity, Vr , of longitudinally stiffened girders as specified in Clause 10.10.5.1.

10.10.7.2 Proportioning When one longitudinal stiffener is used, it shall be placed at a distance 0.2h from the inner surface of the compression flange for doubly symmetric sections and at 0.4dc from the inner surface of the compression flange for monosymmetric sections. If more than one longitudinal stiffener is used, the design shall be based on Approved methods of analysis. Longitudinal stiffeners shall be placed on the side of the girder web opposite to the transverse stiffeners, unless otherwise Approved.

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Longitudinal stiffeners shall be proportioned so that (a) the stiffener width-to-thickness ratio does not exceed 200/ Fy unless the section properties are deemed to be based on an effective width of 200/ Fy ; (b) the projecting stiffener width is less than or equal to 30t ; (c) I  hw3(2.4(a/h)2 – 0.13); and (d)

Fy

r ≥a

1900 where I and r are calculated about a centroidal axis parallel to the web for a section comprising the stiffener or stiffeners and a strip of web 10w wide on each side.

10.10.7.3 Transverse stiffener requirements for longitudinally stiffened webs Transverse stiffeners for girder panels with longitudinal stiffeners shall meet the requirements of Clause 10.10.6. In addition, the section modulus of the transverse stiffener, where I is calculated with respect to the base of the stiffener, shall not be less than St = hSh / 3a. When j is calculated for the purpose of calculating the required moment of inertia, I , of the transverse stiffener in accordance with Clause 10.10.6.2(a), the depth of subpanel, hp , shall be used for calculating h/a. When Clause 10.10.6.2(b) is applied to longitudinally stiffened girders, the depth of subpanel, hp , shall be used for calculating a/h in the equation for As ; the full depth of the web, h, shall be used for calculating C and Vr .

10.10.8 Bearing stiffeners 

10.10.8.1 Web crippling and yielding Bearing stiffeners shall be provided where the factored concentrated loads or reactions at the ULS exceed the factored compressive resistance of the webs of beams or girders. The factored compressive resistance of the web, Br , shall be calculated as follows: (a) for concentrated loads applied at a distance from the member end greater than the member depth, the lesser of (i) Br = bi w (N + 10t )Fy (ii) Br = 1.45fbi w 2 Fy E s where

 bi

= 0.80

N

= length of bearing, mm

t

= flange thickness, mm

(b) for end reactions, the lesser of (i) Br = be w(N + 4t )Fy (ii) Br = 0.60fbe w 2 Fy E s where

 be

= 0.75

N

= length of bearing, mm

t

= flange thickness, mm

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10.10.8.2 Bearing resistance and details Bearing stiffeners shall extend the full depth of the web and shall be fitted to bear against the flange through which the loads are transmitted or be connected to the flange by welds. Stiffeners shall preferably be symmetrical about the web and extend as close to the edge of the flanges as practicable. The width-to-thickness ratio of bearing stiffeners shall not exceed 200/ Fy . The factored bearing resistance of the bearing stiffeners, Br , shall be calculated as Br = 1.50 s As Fy where As

= area of stiffener in contact with the flange, mm2

Fy

= yield stress of the stiffener or flange, MPa, whichever is less

10.10.8.3 Compressive resistance Bearing stiffeners shall be designed as compression members in accordance with Clause 10.9, assuming a column section comprising all of the projecting stiffener element plus a strip of web extending not more than 12w on both sides of each stiffener element. The effective column length shall be taken as not less than 0.75 times the depth of the girder. Connections shall be designed for the interface force transmitted from the web to the stiffeners.

10.10.9 Lateral bracing, cross-frames, and diaphragms 10.10.9.1 Intermediate cross-frames or diaphragms The spacing of intermediate cross-frames or diaphragms shall be determined from an investigation of the lateral torsional buckling resistance of the longitudinal girders, the need to transfer lateral wind forces, and the need to provide torsional restraint to the girders for any anticipated applied torsional loading. Cross-frames and diaphragms shall be designed for the lateral loads they are required to resist plus a lateral load equivalent to 1% of the compression flange force in the beam or girder at the location under consideration. If the intermediate cross-frames or diaphragms are included in the structural model used to determine the forces in the girders, they shall be designed for the forces that they attract. Intermediate cross-frames shall be placed normal to the main members when the supports are skewed more than 20° and shall be designed for the forces they attract. Where girders support deck slabs proportioned in accordance with the empirical design method of Clause 8.18.4, the spacing of intermediate cross-frames, ties, or diaphragms shall satisfy the requirements of Clause 8.18.5.

10.10.9.2 Lateral Bracing If lateral loads are not resisted by the girders alone, a lateral bracing system shall be provided at or close to either the top or bottom flanges. Bracing systems shall be designed to resist a lateral load equivalent to at least 1% of the compression flange force in the beam or girder at the location under consideration, in addition to other applied forces for the limit state under consideration. The bracing system shall have sufficient stiffness to maintain the stability of the braced flange when the system has displaced, at the location under consideration, through the distance required to develop the bracing resistance. A steel or concrete deck used for this function shall be rigidly connected to the compression flange. Timber floors shall not be considered to provide adequate lateral support unless the floor and fastenings are designed for this purpose. Unless otherwise justified by analysis, girder spans longer than 50 m shall have a system of lateral bracing at or close to the bottom flange. As required by Clause A5.1.6, lateral bracing systems shall be designed for the forces they attract in maintaining the compatibility of deformations of girders under vertical loading.

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10.10.9.3 Pier and abutment cross-frames or diaphragms Beam and girder bridges shall have cross-frames or diaphragms at piers and abutments, which shall be proportioned to transmit all lateral forces to the bearings. Cross-frames and diaphragms shall be as deep as practicable. Diaphragms, where practicable, shall support the end of the deck slab.

10.11 Composite beams and girders 10.11.1 General Clause 10.11 shall apply to structures consisting of steel beams or girders and a concrete slab in which resistance to shear at the interface between the beams or girders and the slab is provided by mechanical shear connectors (including bridges that are unshored during placement of the slab). It shall apply to steel beams and girders that are both symmetric and asymmetric about the major axis. Where the beams are shored during casting of the deck, the design methods used shall be subject to Approval.

10.11.2 Proportioning The steel section alone shall be proportioned to support all factored loads applied before the concrete strength reaches 0.75fc’. The lateral restraint conditions existing when the different loads are applied shall be taken into account. The web of the steel section shall be designed to carry the total vertical shear and shall meet the requirements of Clauses 10.10.5 to 10.10.8. The type of concrete, its strength and other properties, and provisions for control of cracking shall comply with Section 8. The effective slab width shall be determined in accordance with Clause 5.8.2.1.

10.11.3 Effects of creep and shrinkage To account for the effect of creep due to that portion of dead load that is applied after the concrete strength has reached 0.75fc’, and in lieu of more detailed calculations, a modular ratio of 3n shall be used in calculating the section properties. For the SLS, a differential shrinkage strain corresponding to the difference between the restrained and the free shrinkage of the concrete shall be considered in the design.

10.11.4 Control of permanent deflections For composite beams and girders, the normal stress in either flange of the steel section due to serviceability dead and live loads shall not exceed 0.90 Fy . The following requirements shall also be satisfied: (a) in positive moment regions:

Md Msd ML + + ≤ 0.90Fy S S3n Sn (b) in negative moment regions:

Md Msd + ML + ≤ 0.90Fy S S′

10.11.5 Class 1 and Class 2 sections 10.11.5.1 General The portions of the steel section in compression shall comply with Clause 10.9.2.

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10.11.5.2 Positive moment regions 10.11.5.2.1 Stress distribution The factored moment resistance of the section in bending shall be calculated using a fully plastic stress distribution, as shown in Figure 10.1.

10.11.5.2.2 Compressive resistance of concrete The factored compressive resistance of the slab used to calculate the factored resistance of the section shall be the smaller of C1 and C2 , calculated as follows: C1 = Cc + Cr C2 =  sAsFy where 

Cc

= 0.85 c Betc fc‘

Cr

=  r Ar fy

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Compression zone frfy 0.85fcfc’

Be Ar a

tc

yt d yb

ds’

Cr Cc ec er

Centre of gravity of steel section

Ts

As

fsFy

(a) Plastic neutral axis in the concrete slab frfy

Be

0.85fcfc’

Ar tc tt Plastic neutral axis of composite section

yt’

Cc

ytc d

ybc

ds’

Cr

As

fsFy h

Cs ec

er

es

Ts tb

yb’ fsFy

(b) Plastic neutral axis in the steel section 

Figure 10.1 Class 1 and 2 sections in positive moment regions (See Clauses 10.11.5.2.1, 10.11.5.2.3, and 10.11.5.2.4.)



10.11.5.2.3 Plastic neutral axis in concrete When C 1 is greater than C 2 , the plastic neutral axis is in the concrete slab as shown in Figure 10.1(a), and the depth of the compressive stress block, a, shall be calculated as

a=

C 2 − fr Ar fy 0.85fc Be fc′

The factored moment resistance, Mr , of the section shall be calculated as Mr = Cc ec + Cr er where Cc = 0.85 c Be afc‘ October 2011 (Replaces p. 465, May 2010)

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10.11.5.2.4 Plastic neutral axis in steel When C1 is less than C2 , the plastic neutral axis is in the web as shown in Figure 10.1(b), and the depth of the compressive stress block, a, shall be taken as equal to tc . The factored moment resistance, Mr , shall be calculated as Mr = Cc ec + Cr er + Cs es where Cc

= 0.85 c Betc fc‘

Cs

= 0.5( s As Fy – C1)

10.11.5.3 Negative moment regions 

10.11.5.3.1 Moment resistance of composite section When shear connectors are provided and either the slab reinforcement is continuous over interior supports or the slab is prestressed longitudinally, the factored moment resistance, Mr , of the section shall be determined as follows: (a) When it is braced against lateral torsional buckling, Mr shall be calculated on the basis of a fully plastic stress distribution in the structural steel, reinforcement, and prestressing strands, as shown in Figure 10.2: Mr = Tr er + Ts es where Tr =  r Ar fy Ts = 0.5(s As Fy – Tr) (b) Otherwise, Mr shall be based on its lateral torsional buckling resistance. In the absence of a more detailed analysis, the unbraced bending resistance of the structural steel section alone, calculated in accordance with Clause 10.10.2.3, shall be used. The requirements of Clause 8.5.3 shall also be satisfied. When shear connectors are not provided in the negative moment regions, the factored moment resistance shall be taken as that of the steel section alone, calculated in accordance with Clause 10.10.2. frfy

Be Ar

Tr

tc

yt’

Ts

er

Neutral axis d

es

As

fsFy

Cs yb’

fsFy



Figure 10.2 Class 1 and 2 sections in negative moment regions (See Clause 10.11.5.3.1.)

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10.11.5.3.2 Longitudinal reinforcement in non-prestressed slabs

When the longitudinal tensile stress in non-prestressed deck slabs at SLS exceeds  c fcr , the longitudinal reinforcement, including longitudinal distribution reinforcement, shall not be less than 1% of the cross-sectional area of the slab. At least two-thirds of this reinforcement shall be placed in the top layer of the slab reinforcement and within the effective width of the slab.

10.11.5.3.3 Negative moment regions without shear connectors When shear connectors are not provided in the negative moment region, the longitudinal reinforcement shall be extended into the positive moment regions in accordance with Clause 8.15, and additional shear connectors shall be provided in accordance with Clause 10.17.2.7.

10.11.6 Class 3 sections 10.11.6.1 Width-to-thickness ratios The portions of the steel section in compression shall comply with Clause 10.9.2.

10.11.6.2 Positive moment regions 10.11.6.2.1 Moment resistance For composite sections in which the depth of the compression portion of the web of the steel section, calculated on the basis of a fully plastic stress distribution, equals or is less than 850w/ Fy , the factored moment resistance shall be determined in accordance with Clause 10.11.5.2.

10.11.6.2.2 Moment resistance of slender members When the depth of the compression portion of the web of the steel section, calculated in accordance with Clause 10.11.6.2.1, exceeds 850w/ Fy , the factored moment resistance, Mr , of the composite section shall be calculated on the basis of fully plastic stress blocks, as shown in Figure 10.3, as follows: M r = C c ec + C r er + C s es where 

Cc

= 0.85c Betc fc‘

Cr

=  r Ar fy

Cs

=  s A‘sc Fy The area of the steel section in compression, A‘sc , shall include the top flange and a web area of

(850w 2)/ Fy , and the area of the steel section in tension, A‘st , shall be calculated as follows:

Ast′ =

Cc + Cr + C s fs Fy

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f rf y

Be 0.85fcfc’

Ar tc

tt

Cr

yt’

Cc Cs

850 w/ Fy

ec

As

d

er

es

w

Ts

yb’ fsFy



Figure 10.3 Class 3 Sections in positive moment regions (See Clause 10.11.6.2.2.)

10.11.6.3 Negative moment regions 10.11.6.3.1 Composite sections 10.11.6.3.1.1 When (a) shear connectors are provided; and (b) slab reinforcement is continuous over interior supports or the slab is prestressed longitudinally, the factored moment resistance of the composite section shall be taken as the resultant moment based on the linear stress distribution at first yielding or buckling, as shown in Figure 10.4, and the requirements specified in Clause 10.11.6.3.1.2 shall be satisfied.

10.11.6.3.1.2 

The following requirements shall be satisfied: (a) Mfd /S + (Mfsd + Mfl )/S‘  sFcr

where S and S‘ are the elastic section moduli with respect to the bottom fibre, Fcr = Mr /sS, and Mr is determined in accordance with Clause 10.10.3.3, based on the steel section, or a more detailed analysis of its lateral torsional buckling resistance.

(b) Mfd /S + (Mfsd + Mfl )/S‘   sFy where S and S‘are the elastic section moduli with respect to the top fibre of the steel section. (c) (Mfsd + Mfl )/S‘   rfy where S‘ is the elastic section modulus with respect to the centroid of the top layer of longitudinal slab reinforcement. The applicable requirements of Clauses 8.5.3 and 10.11.5.3.2 shall also be satisfied.

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fsFy fr f y

+

Mfd S Dead load on bare steel girder

=

< – fsFcr

Mfsd + Mfl S′ Superimposed dead plus live load on composite girder

Total accumulated stresses

Figure 10.4 Class 3 Sections in negative moment regions (See Clause 10.11.6.3.1.)

10.11.6.3.2 Non-composite sections When shear connectors are not provided in the negative moment regions, the factored moment resistance shall be taken as that of the steel section alone, calculated in accordance with Clause 10.10.3. The requirements of Clause 10.11.5.3.3 shall also be satisfied.

10.11.7 Stiffened plate girders 10.11.7.1 Width-to-thickness ratios Stiffened plate girders shall meet the requirements of Clauses 10.10.4.1 and 10.10.4.2.

10.11.7.2 Positive moment regions 10.11.7.2.1 Moment resistance For composite sections in which the depth of the compression portion of the web of the steel section, calculated on the basis of a fully plastic stress distribution, does not exceed 850w/ Fy , the factored moment resistance shall be determined in accordance with Clause 10.11.5.2.

10.11.7.2.2 Moment resistance of slender webs When the depth of the compression portion of the web of the steel section calculated in accordance with Clause 10.11.7.2.1 exceeds 850w/ Fy , whether or not longitudinal stiffeners are provided, the factored moment resistance of the composite section shall be calculated on the basis of fully plastic stress blocks, as in Clause 10.11.6.2.2.

May 2010 (Replaces p. 469, November 2006)

469

S6S1-10

© Canadian Standards Association

10.11.7.3 Negative moment regions 10.11.7.3.1 Composite sections When (a) shear connectors are provided; and (b) slab reinforcement is continuous over interior supports or the slab is prestressed longitudinally, the factored moment resistance of the section shall be calculated in accordance with Clause 10.11.6.3.1. If longitudinal stiffeners are not provided and 2dc /w > 1900 Fy , the factored moment resistance shall be reduced by the factor specified in Clause 10.10.4.3.

10.11.7.3.2 Non-composite sections When shear connectors are not provided in the negative moment region, the factored moment resistance shall be taken as that of the steel section alone (see Clause 10.10.4). The requirements of Clause 10.11.5.3.3 shall also apply.

10.11.8 Shear connectors 10.11.8.1 General Shear connectors shall comply with the applicable materials specification of Clause 10.4 and shall be capable of resisting both horizontal and vertical movements between the concrete slab and the steel beam or girder. The fatigue resistance of the base metal at the connection weld of shear connectors shall meet the requirements of Clause 10.17.2.3. The fatigue resistance of stud shear connectors shall meet the requirements of Clause 10.17.2.7. 

10.11.8.2 Cover and edge distances The clear depth of concrete cover over the top of shear connectors shall meet the requirements of Clause 8.11.2.2. Shear connectors shall extend into the concrete deck so that the clear distance from the underside of the head of the shear connector to the top of the bottom transverse reinforcement or, when the slab is haunched, to the top of the transverse reinforcement in the slab haunch, is at least 25 mm. The clear distance between the edge of a girder flange and a shear connector shank shall be at least 25 mm.



10.11.8.3 Resistance, placement, and spacing In determining the resistance of shear connectors, connector strength and spacing, concrete strength and, where stud connectors are embedded in grout, grout strength, including grout side cover to the studs, shall be taken into consideration. Use of connectors that are fastened to the steel section by means other than welding shall require Approval. The minimum number of shear connectors in each shear span shall be calculated as follows: N = P/qr where a shear span is a segment between points of maximum and zero moment at the ULS and P is determined as follows: (a) for positive moment: (i) when the plastic neutral axis is in the concrete slab: P = sAsFy ; and (ii) when the plastic neutral axis is in the steel section: P = 0.85cfc’ betc + r Arfy ; and (b) for negative moment: P = r Arfy. The factored shear connector resistance, qr , shall be determined in accordance with Clauses 10.11.8.3.1 to 10.11.8.3.3.



10.11.8.3.1 Stud connectors in cast-in-place deck slab

The factored shear resistance, qr , of a headed stud shear connector with h/d  4 shall be taken as

qr = 0.5fsc Asc fc′Ec ≤ fsc Fu Asc

470

May 2010 (Replaces p. 470, November 2006)

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

where Fu

= minimum tensile strength of the stud steel (450 MPa for CSA W59 Type B studs)

Asc

= cross-sectional area of one stud shear connector, mm2

The spacing of shear connectors shall not be less than 4d, nor greater than 600 mm. Stud connectors shall be spaced uniformly in a shear span or spaced according to the variation in the interface shear. 

10.11.8.3.2 Stud connectors in full-depth precast panels This Clause applies to full-depth precast panels where grout pockets (blockouts) are provided to accommodate clusters of stud connectors welded to the steel section. The pockets are filled with non-shrink grout to provide composite action. The grout pockets shall be shaped to prevent vertical separation between the deck slab and the steel section unless other means of interlocking are provided. The concrete used in the precast panels shall have f’c  35 MPa and the compressive strength of the grout shall be equal to or greater than the f’c of the concrete. The precast panels shall meet all the requirements of Section 8. Local effects due to the actions of the studs shall also be considered. Post-tensioning, when specified, shall precede the grout placement. The maximum spacing of stud clusters shall not exceed 1200 mm. The minimum spacing of studs within the pocket shall be 4d. The grout side cover, taken as the shortest distance from the grout pocket perimeter to the shank of the nearest stud, shall be greater than or equal to 1.5d. The factored resistance of a stud shear connector, qr , shall be determined in accordance with Clause 10.11.8.3.1. In this calculation, the values for f’c and Ec shall be based on the compressive strength of the grout. The grout strength shall not be greater than 1.3 times the f’c of the precast concrete. Where the stud cluster spacing exceeds 600 mm, the minimum number of studs per cluster shall vary according to the variation in the interface shear. The use of stud connectors 25 mm in diameter or larger shall require Approval.



10.11.8.3.3 Channel connectors in cast-in-place deck slab In solid slabs of normal-density concrete, the factored shear resistance for channel shear connectors shall be taken as

qr = 45fsc (t + 0.5w ) Lc fc′ where t

= average thickness of channel shear connector flange, mm

w

= thickness of channel shear connector web, mm

Lc

= length of channel shear connector, mm

Channel connectors shall be spaced according to the variation in the interface shear.

10.11.8.4 Longitudinal shear The longitudinal factored shear resistance along any potential shear planes shall be greater than the factored longitudinal shear. The factored longitudinal shear in the slab of a composite beam, Vu , shall be taken as

Vu = S qr − 0.85fc Ac fc′ − fr ArLfy For normal-weight concrete, the factored shear resistance along any potential shear surface in the concrete slab shall be calculated as

Vr = 0.80fr Art fy + 2.76fc Acv ≤ 0.50fc Acv fc′ For lightweight concrete, the constant 2.76 with units of MPa shall be replaced by 1.38.

May 2010 (Replaces p. 471, November 2006)

471

S6S1-10

© Canadian Standards Association

10.11.9 Lateral bracing, cross-frames, and diaphragms The requirements of Clause 10.10.9 shall be met.

10.12 Composite box girders 10.12.1 General Clause 10.12.1 applies to the design of simple and continuous composite box girder bridges of spans up to 110 m, consisting of one or more straight steel single-cell box girders, acting compositely with a concrete deck, and symmetrical about a vertical axis. For longer spans, other requirements may apply. The top of the box may be open with twin steel flanges or closed with a steel flange plate. Exterior access holes with hinged and locked doors shall be provided. Openings in box sections shall be screened to exclude animals. The requirements of Clauses 10.11.2 to 10.11.4 shall also apply.

10.12.2 Effective width of tension flanges The effective width of bottom flange plates in tension shall be taken as not more than one-fifth of the span for simply supported structures and not more than one-fifth of the distance between points of contraflexure under dead load for continuous structures.

10.12.3 Web plates Webs shall be proportioned in accordance with Clause 10.10 and, for single box girders, in accordance with Clause 10.12.8.5. The shear force to be considered on each web shall be Vf / cos  , where Vf is one-half of the total vertical shear force at the ULS on one box girder and  is the angle of inclination of the web plate to the vertical. The inclination of the web plates shall not exceed 1 horizontal to 4 vertical.

10.12.4 Flange-to-web welds The total effective throat of the flange-to-web welds shall not be less than the thickness of the web unless internal diaphragms or cross-frames are spaced in accordance with Clause 10.12.6.1 and a minimum of two intermediate diaphragms per span are used inside the box. If fillet welds are used, they shall be placed on both sides of the connecting flange or web plate.

10.12.5 Moment resistance 10.12.5.1 Composite and non-composite sections 10.12.5.1.1 The factored moment resistance of the steel section acting alone before the attainment of composite action shall be determined in accordance with (a) Clauses 10.10, 10.12.2, and 10.12.8.4 for regions of positive moment; and (b) Clauses 10.10 and 10.12.5.2 to 10.12.5.4 for regions of negative moment, using the elastic section modulus of the steel section alone.

10.12.5.1.2 The factored moment resistance of the composite section shall be determined in accordance with (a) Clauses 10.11, 10.12.2, and 10.12.8.4 for regions of positive moment; and (b) Clause 10.11 for regions of negative moment, except that in applying Clause 10.11.6.3.1.1 or 10.11.6.3.1.2, Fcr shall be determined in accordance with the applicable requirements of Clauses 10.12.5.2 to 10.12.5.4.

472

May 2010 (Replaces p. 472, November 2006)

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.12.5.2 Unstiffened compression flanges The factored moment resistance with respect to the compression flange shall be calculated as follows: (a) when b/t 510/ Fy : Mr =  s FyS‘ (b) when 510/ Fy < b/t 1100/ Fy : Mr =  s FcrS‘ where Fcr

πC ⎤ ⎡ 0.592Fy ⎢1+ 0.687 sin 2 ⎥⎦ ⎣ where =

C

=

1100 − (b / t ) Fy 590

(c) when b/t > 1100/ Fy : Mr =  s FcrS‘ where Fcr

=

7.24 × 105 (b / t )2

10.12.5.3 Compression flanges stiffened longitudinally 10.12.5.3.1 The factored moment resistance with respect to the compression flange shall be calculated as follows: (a) when :bs / t ≤ 255 k1 / Fy Mr =  s FyS‘ (b) when :255 k1 / Fy < bs / t ≤ 550 k1 / Fy Mr =  s FcrS‘

May 2010

472A

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

where Fcr

πC ⎤ ⎡ 0.592Fy ⎢1+ 0.687 sin s ⎥ 2 ⎦ ⎣ where =

550 k1 − (bs / t ) Fy

=

Cs

295 k1

(d) when :bs / t > 550 k1 / Fy Mr =  s FcrS‘ where Fcr

=

18k1 × 104 (bs / t )2

10.12.5.3.2 The buckling coefficient, k1, in Clause 10.12.5.3.1 shall be determined as follows: (a) For n = 1:

⎡ 8I ⎤ k1 = ⎢ s3 ⎥ ⎢⎣ bst ⎥⎦

1/ 3

≤ 4.0

(b) For n > 1:

⎡ 14.3I ⎤ k1 = ⎢ 3 4s ⎥ ⎢⎣ bst n ⎥⎦

1/ 3

≤ 4.0

where n = number of longitudinal stiffeners Is

= moment of inertia of each stiffener about an axis parallel to the flange and at the base of the stiffener, mm4

10.12.5.3.3 The longitudinal stiffeners shall be equally spaced across the flange width. A transverse stiffener shall be placed near the point of contraflexure under dead load and shall be equal in size to a longitudinal stiffener.

10.12.5.4 Compression flanges stiffened longitudinally and transversely The factored moment resistance with respect to the compression flange shall be calculated as follows: (a) when :bs / t ≤ 255 k2 / Fy Mr = sFyS‘ (b) when :255 k2 / Fy < bs / t ≤ 550 k2 / Fy Mr = sFcrS‘ where Fcr

=

πC ⎤ ⎡ 0.592Fy ⎢1+ 0.687 sin s ⎥ 2 ⎦ ⎣

October 2011 (Replaces p. 473, May 2010)

473

S6S2-11

© Canadian Standards Association

where

550 k2 − (bs / t ) Fy

=

Cs

295 k2

(c) when b : s / t > 550 k2 / Fy Mr = sFcrS‘ where Fcr

=

k2

=

18k2 × 104 (bs / t )2 [1+ (a / b )2 ]2 + 87.3 (n + 1)2 (a / b )2 [1+ 0.1(n + 1)]

The longitudinal stiffeners shall be equally spaced across the flange width and shall be proportioned so that the moment of inertia of each stiffener, Is , about a transverse axis at the base of the stiffener is at least equal to Is = 8t3bs The transverse stiffeners shall be proportioned so that the moment of inertia of each stiffener, It , about a longitudinal axis through its centroid is at least equal to 

It = 0.055 (n + 1)3 bs3

Fcr Af Es a

The ratio a /b shall not exceed 3.0. The maximum value of the buckling coefficient k2 shall be 4.0. When k2 has its maximum value, the transverse stiffeners shall have a spacing, a, equal to or less than 4bs. The transverse stiffeners need not be connected to the flange plate but shall be connected to the webs of the box and to each longitudinal stiffener. The connection to the web shall be proportioned for a vertical force, Rw , of

Rw =

fs Fy St

2b The connection to each longitudinal stiffener shall be proportioned for a vertical force, Rs , of

Rs =

fs Fy St nb

10.12.6 Diaphragms, cross-frames, and lateral bracing 10.12.6.1 Diaphragms and cross-frames within girders Internal diaphragms, cross-frames, or other means shall be provided at each support to resist transverse rotation, displacement, and distortion and to transfer vertical, transverse, and torsional loads to the bearings. The effect of access holes shall be considered and adequate reinforcement provided if necessary. Intermediate internal diaphragms or cross-frames shall be used to control deformation, torsional warping, and distortion of open box girders during fabrication, transportation, erection, and placement of the deck. Cross-frames, diaphragms, or cross-ties between top flanges shall be used in open trapezoidal box girders to resist the transverse resultant induced by the sloping web force opposing the vertical loads acting on the top flanges during construction.

474

October 2011 (Replaces p. 474, May 2010)

© Canadian Standards Association

Canadian Highway Bridge Design Code

Vertical stiffeners used as connecting plates for diaphragms or cross-frames shall be connected to both flanges. For single box girder bridges, internal intermediate diaphragms or cross-frames shall be placed at intervals not greater than 8 m unless it can be shown that the degree of cross-sectional distortion is not critical.

10.12.6.2 Diaphragms and cross-frames between girders When diaphragms and cross-frames are included in the structural model used to determine the forces in the girders, they shall be designed for the forces that they attract. Where girders support deck slabs proportioned in accordance with the empirical design method of Clause 8.18.4, the spacing of intermediate cross-frames or diaphragms shall satisfy the requirements of Clause 8.18.5.

10.12.6.3 Lateral Bracing The need for lateral bracing shall be assessed for all stages of construction as well as for the service condition. The bracing shall be designed for the forces it attracts. For multiple open-box girders, the need for lateral bracing between the flanges of individual boxes shall be investigated to ensure that deformations and stability of the box sections are adequately controlled during fabrication, erection, and deck construction. Top bracing shall be placed as close to the plane of the top flanges as possible, except that the requirements of Clause 10.17.3.2.2 shall also be met. If the bracing is attached to the webs below the plane of the top flanges, a means shall be provided to transfer horizontal forces from the bracing to the top flanges. Bridges consisting of a single trough-type open-box section shall have top lateral bracing between the flanges. The bracing shall be designed to resist the shear flow in the section prior to the curing of the concrete deck. Forces in the bracing due to flexural bending shall also be considered. The structural section assumed to resist the portion of factored horizontal wind or seismic loading in the plane of the bottom flange shall consist of the bottom flange acting as a web and 12 times the thickness of the webs acting as flanges.

10.12.7 Multiple box girders 10.12.7.1 General The distance centre-to-centre of flanges of each box shall be the same. The distance centre-to-centre of flanges of adjacent boxes at mid-span shall be within the range of 0.80 to 1.20 of the distance centre-to-centre of the flanges of each adjacent box. When the boxes are not parallel, the distance centre-to-centre of adjacent flanges at supports shall be within the range of 0.65 to 1.35 of the distance centre-to-centre of the flanges of each adjacent box. The cantilever overhang of the deck slab, including curb and parapet, shall not exceed 0.60 of the average distance between the centres of the top steel flanges of the exterior box section or 1800 mm, unless special precautions are taken during design and construction.

10.12.7.2 Relative deflection of boxes of multiple box girders Control of cracking in the deck slab due to relative deflection of box girders shall be considered, taking into account the requirements of Clauses 5.7.1.2 and 10.12.6.2.

10.12.8 Single box girders 10.12.8.1 General Single box girder sections shall be symmetric about a vertical axis and the line of action of the dead load shall be as close to the shear centre of the box as practicable. Structural steel in tension under dead load shall be considered fracture critical unless analysis shows that the full dead and live load can be supported after a notional complete fracture of the tension steel occurs at any cross-section. November 2006

475

CAN/CSA-S6-06

© Canadian Standards Association

Thermal forces shall be considered in the design. Uplift at the bearings shall be considered for ULS load combinations. Sufficient internal cross-frames shall be provided to maintain the shape of the cross-section under the action of eccentric loads and to limit distortional bending and warping. Longitudinal warping normal stresses shall be taken into account for fatigue, but need not be considered for the ULS.

10.12.8.2 Analysis The analytical model used shall permit the assessment of both torsional and flexural effects for all load conditions. The transverse positions of the bearings shall be modelled so that the reactions can be calculated directly for all load conditions, including eccentric live loads. Live loads shall be positioned so as to cause the maximum flexural/torsional effect on the girder component being investigated. Load effects from multiple traffic lanes shall be investigated.

10.12.8.3 Bearings Bearings for single box girders shall be located to ensure stability of the bridge against overturning under all conditions of loading. If single bearings are used, the remaining double bearings shall be sufficient to prevent overturning under all conditions of loading. Single bearings shall be located vertically below the shear centre of the box girder to the extent practicable.

10.12.8.4 Moment resistances The factored moment resistance of single box girders shall be determined in accordance with Clause 10.12.5 using a reduced normal stress, Rv Fy , for the tensile resistance of the bottom flange in place of Fy , with Rv as follows:

⎡f ⎤ Rv = 1− 3 ⎢ s ⎥ ⎢⎣ Fy ⎥⎦

2

10.12.8.5 Combined shear and torsion Both the web plates and the shear connectors shall be proportioned for the sum of the factored shears due to bending and torsion.

10.13 Horizontally curved girders 10.13.1 General Clauses 10.13.2 to 10.13.8 shall apply to all simple and continuous bridges that are curved in plan, are up to 60 m in span, and employ either rolled or fabricated sections. For longer spans, other considerations may apply.

10.13.2 Special considerations Note: The design of curved girders necessitates special consideration of super-elevation and centrifugal forces, thermal forces, and uplift.

10.13.2.1 Dynamic load allowance The dynamic load allowance shall be as specified in Clause 3.8.4.5 unless a dynamic analysis is used.

476

November 2006

© Canadian Standards Association

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.13.2.2 Super-elevation and centrifugal forces The super-elevation of the deck shall be considered when the wheel loads due to the combined effects of the centrifugal forces and the vertical live loads are being determined.

10.13.2.3 Thermal forces Tangential and radial movements, potential uplift at the bearings, and induced restraining forces due to the temperature changes and gradients shall be taken into account.

10.13.2.4 Uplift The structure shall be assessed for uplift at the supports. The assessment for dead loads shall take into account the intended sequence of construction.

10.13.3 Design theory 10.13.3.1 General The whole structure shall be modelled in the analysis, including the transverse members. The analysis shall include, in addition to the torsional shear stresses, an evaluation of the longitudinal stresses due to restrained warping of members with non-uniform torsion.

10.13.3.2 Limiting curvature Provided that the conditions of Clause A5.1.3.2 are met, the bridge shall be considered straight for the purposes of structural analysis.

10.13.4 Bearings Bearings shall be designed to resist the vertical loads (including uplift) and the horizontal loads to which they could be subjected (including centrifugal force effects) and be designed and oriented to permit thermal movement consistent with the design assumptions. 

10.13.5 Diaphragms, cross-frames, and lateral bracing Unless otherwise Approved, longitudinal girders shall be connected at each support by diaphragms designed to prevent twisting of the girders. Diaphragms or cross-frames shall be provided between I-girders, i.e., at intervals between supports, to further facilitate resistance to twisting of the girders. Each line of diaphragms or cross-frames shall extend continuously across the full width of the bridge. Diaphragms or cross-frames shall be provided between box girders where needed to augment the resistance of the girders to torsion. Diaphragms or cross-frames shall be provided inside the girders in line with those provided between the girders. Diaphragms and cross-frames shall be treated as main structural members and, as such, they shall satisfy the material toughness requirements of Clause 10.23.3. They shall be approximately as deep as the girders they connect and shall be connected to the girders to transfer all of the loads that they attract. In addition to the diaphragms or cross-frames used to control torsion, other cross-frames shall be provided in box girders, if necessary, to resist the distortional effects of eccentric loads on the cross-section. The need for lateral bracing between the top flanges of curved box girders and between I-girders to ensure stability and resist the effects of wind shall be assessed for all stages of construction as well as for service conditions. Where girders support deck slabs proportioned in accordance with the empirical design method of Clause 8.18.4, the lateral spacing of intermediate cross-frames or diaphragms shall satisfy the requirements of Clause 8.18.5.

October 2011 (Replaces p. 477, May 2010)

477

S6S2-11

© Canadian Standards Association

10.13.6 Steel I-girders 10.13.6.1 Non-composite girder design 10.13.6.1.1 Limits of applicability The following requirements shall apply: (a) The absolute value of the ratio of the torsional warping normal stress to the normal flexural stress shall, as far as possible, not exceed 0.5 at any point in the girder. (b) The unbraced length between cross-frames shall not exceed 25 times the width of the flange or 0.1 times the mean radius of the girder. (c) Flanges shall be Class 3 or better.

10.13.6.1.2 Flanges Flanges shall be proportioned to satisfy the following requirements: (a) Strength of either flange:

Mfx Mfw + 2 t Fy

(b) When 0.75Fy / 3 < fs ≤ Fy / 3 and Mr = φ sRv Fy S’

bs R ≤ 1 , the factored moment resistance, Mr , shall be taken as t Fy

where

255 k1 R1

=

0.5 ⎤ ⎡ 2 ⎡ ⎡ fs ⎤ ⎡ k1 ⎤ 2 ⎤ ⎥ 1⎢ 2 Rv + ⎢Rv + 4 ⎢ ⎥ ⎢ ⎥ ⎥ ⎥ ⎢ 2⎢ ⎢⎣ Fy ⎦⎥ ⎣ ks ⎦ ⎥⎦ ⎥ ⎢ ⎣ ⎣ ⎦

550 k1 R2

=

Cs

=

⎡ ⎡ ⎡ 1 ⎢ ⎢(Rv − 0.4 )2 + 4 ⎢ fs 0 4 − . + R ( ) v ⎢ 1.2 ⎢ ⎢⎣ Fy ⎢ ⎣ ⎣

⎤ ⎡ k1 ⎤ 2 ⎤ ⎥ ⎢ ⎥ ⎥ ⎥⎦ ⎣ ks ⎦ ⎥⎦ 2

0.5 ⎤

⎥ ⎥ ⎥ ⎦

⎡b ⎤ R2 − ⎢ s ⎥ Fy ⎣t ⎦ R2 − R1 2

Fcr

=

⎡b ⎤ fs2k1 ⎢ s ⎥ 18k1 × 10 ⎣t ⎦ − 2 2 4 k 18 ⎡ bs ⎤ s × 10 ⎢⎣ t ⎥⎦

November 2006

4

481

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© Canadian Standards Association

where k1 = the buckling coefficient, which shall not exceed 4.0 and, when at least one longitudinal stiffener is provided,

ks

=

⎡ I ⎤ 5.34 + 2.84 ⎢ s 3 ⎥ ⎣ bst ⎦ (n + 1)2

1/ 3

≤ 5.34

where Is

=

moment of inertia of stiffener, designed and detailed in accordance with Clause 10.12.5.3

10.13.7.4.2.2 Unstiffened compression flanges The requirements of Clause 10.13.7.4.2.1 shall apply to unstiffened compression flanges, except that the following values shall apply: (a) k1 = 4; (b) ks = 5.34; and (c) bs = b = width of flange between webs.

10.13.8 Camber Girders shall be cambered for dead load deflections, including twisting effects. When heat-curved girders are used, they shall be provided with additional camber in accordance with Clause 10.7.4.3.

10.14 Trusses 10.14.1 General Main truss members shall be symmetrical about the centroidal longitudinal vertical plane of the truss. When the centroidal axes of axially loaded members joined at their ends do not intersect at a common point, the effect of connection eccentricity shall be taken into account. The fabricated length of members shall be such that the resulting camber of the truss is in accordance with Clause 10.7.4. The design of gusset plates shall be in accordance with Clause 10.18.5.2.

10.14.2 Built-up members 10.14.2.1 General Unless otherwise Approved, the components shall be connected by solid plates. Batten plates shall be ignored in calculating the radius of gyration of the section. Diaphragms or stiffeners shall be provided in trusses at the end connections of floor beams.

10.14.2.2 Tie plates The separate components of tension members composed of shapes shall be connected by tie plates or other Approved means. The length of end tie plates shall not be less than 1.25 times the distance between the inner lines of the fasteners or welds connecting them to the flanges. Intermediate tie plates shall have a length at least 0.5 times the distance between the inner lines of the fasteners or welds connecting them to the flanges. Tie plates shall have a thickness not less than 0.02 times the distance between the fasteners or welds connecting them to the flanges. A diaphragm between gusset plates engaging main members shall be provided if the end tie plate is 1200 mm or more from the point of intersection of the members.

482

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

10.14.2.3 Perforated cover plates The thickness of perforated cover plates shall be not less than the unsupported width multiplied by Fy /840. Perforated cover plates shall be proportioned so that (a) the transverse distance from the edge of a perforation to the nearest line of connecting fasteners or welds does not exceed 12 times the thickness of the plate; (b) the length of perforations in the longitudinal direction does not exceed twice the width; (c) the clear distance between perforations in the longitudinal direction is not less than the clear distance between the inner lines of connecting fasteners or welds; (d) the clear distance between the end perforation and the end of the plate, or the end of half perforation, is not less than 1.25 times the clear distance between the inner lines of connecting fasteners or welds; and (e) no part of a perforation has a radius smaller than 25 mm.

10.14.2.4 Battens for compression members The use of battened compression members shall be limited to members not subjected to bending in the plane of the battens. The spacing of battens shall meet the following requirements: (a) if the slenderness ratio of the member about the axis perpendicular to the battens is equal to or less than 0.8 times the slenderness ratio of the member about the axis parallel to the battens, the spacing of battens centre-to-centre of end fasteners or the clear distance between welds shall be such that the slenderness ratio of either main component over that distance shall not exceed 50 or 0.7 times the slenderness ratio of the member about the axis parallel to the battens; and (b) if the slenderness ratio of the member about the axis perpendicular to the battens exceeds 0.8 times the slenderness ratio of the member about the axis parallel to the battens, the spacing of battens centre-to-centre of end fasteners or the clear distance between welds shall be such that the slenderness ratio of either main component over that distance shall not exceed 40 or 0.6 times the slenderness ratio of the member as a whole about its weaker axis. Battens such as plates, channels, or beam sections shall be bolted or welded to the main components so as to resist simultaneously a longitudinal shear force of

Vf =

0.025Cf d na

and a moment of

Mf =

0.025Cf d 2n

The effective length of a batten shall be taken as the longitudinal distance between end bolts or end welds, or as the length of continuous welds. Battens shall have an effective length not less than the distance between the innermost connecting bolts or welds, or less than twice the width of one main component in the plane of the batten. Except for batten plates with stiffened edges or rolled shapes with flanges perpendicular to the main components, the thickness of batten plates shall be not less than 0.02 times the minimum distance between the innermost lines of connecting bolts or welds.

10.14.3 Bracing 10.14.3.1 Top and bottom bracing Through-truss spans, deck-truss spans, and spandrel-braced-arch spans shall have top and bottom lateral bracing systems.

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10.14.3.2 Chord bracing The use of lateral bracing shallower than the chords shall require Approval. Bracing shall be connected effectively to both flanges of the chords.

10.14.3.3 Through-truss spans Through-truss spans shall have portal bracing rigidly connected to the end post and top chord flanges. Portal bracing shall be proportioned to take the full reaction of the top chord lateral system and the end posts shall be proportioned for the reaction. Sway bracing shall be located at the necessary panel points.

10.14.3.4 Deck-truss spans Deck-truss spans shall have sway bracing in the plane of the end posts. Unless an analysis performed in accordance with Section 5 indicates that sway bracing is unnecessary, sway bracing shall be provided at all intermediate panel points and shall extend the full depth of the trusses below the floor system. The end sway bracing shall be proportioned to carry all of the upper lateral forces to the supports through the end posts of the truss.

10.14.3.5 Minimum force Bracing systems between straight compression members or straight flanges shall be designed to carry the shear forces from external loads plus 1% of the compression forces in the supported members or flanges.

10.14.3.6 Half-through trusses and pony trusses The top chord of a half-through or pony truss shall be designed as a column with elastic lateral supports at each panel point. The factored compressive resistance of the column shall be at least equal to the maximum force in any panel of the top chord resulting from loads at the ULS. The vertical truss members, floor beams, and connections between them shall be proportioned to resist at the ULS a lateral force of at least 8 kN/m applied at the top chord panel points.

10.15 Arches 10.15.1 General The design of solid web arch ribs at the ULS shall be based on an amplified first-order analysis or a second-order analysis in accordance with Section 5 and take into account the deformations that occur at the ULS load levels.

10.15.2 Width-to-thickness ratios The width-to-thickness ratios of flanges and web stiffeners of arch ribs shall meet the requirements for Class 1 or 2 sections specified in Clause 10.9.2. The width-to-thickness ratio, h/w, of webs of arch ribs shall not exceed 560/ Fy , 840/ Fy , or 1120/ Fy for a web with no, one, or two longitudinal stiffeners, respectively.

10.15.3 Longitudinal web stiffeners The moment of inertia, Is , of a longitudinal web stiffener about an axis at its base shall not be less than 0.75h t 3 when one stiffener is provided or 2.2h t 3 when two stiffeners are provided.

10.15.4 Axial compression and bending Arch ribs required to resist bending moments in addition to an axial compressive force shall be proportioned to meet the requirements of Clause 10.9.2 for Class 2 sections.

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10.15.5 Arch ties Arch ties shall be considered fracture-critical members unless constructed of several components in such a manner that a fracture of one component does not propagate into another.

10.16 Orthotropic decks 10.16.1 General Clause 10.16 shall apply to the design of orthotropic steel decks comprising a deck plate stiffened and supported by longitudinal ribs and transverse floor beams. Connections between the deck and other structural members shall be designed to ensure full interaction. The effects of distortion of the cross-sectional shape due to torsion shall be taken into account in the analysis of orthotropic box girder bridges.

10.16.2 Effective width of deck 10.16.2.1 Ribs The effective width of deck plate acting as the top flange of a longitudinal rib shall be calculated in accordance with Clause 5.8.2.2.1 or by another Approved method.

10.16.2.2 Girders and transverse beams The effective width of a deck acting as the top flange of a longitudinal superstructure component or transverse beam shall be calculated in accordance with Clause 5.8.2.2.2 or by another Approved method.

10.16.3 Superposition of local and global effects 10.16.3.1 General In calculating extreme force effects in the deck, the global or overall effects induced by flexure and axial forces in the main longitudinal girders and the local effects for the same configuration and position of live load shall be superimposed.

10.16.3.2 Decks in longitudinal tension Decks subject to global tension and local flexure shall be proportioned so that

Tf Mfr + ≤ 1.33 Tr Mrr where Tf , the factored tensile force induced in the deck by flexure and axial tension in the main longitudinal girders, increased for simultaneous global shear, is Ade (fg2 + 3 fvg2 )0.5.

10.16.3.3 Decks in longitudinal compression Unless it can be shown by rigorous analysis that overall buckling of the deck will not occur as a result of the global compressive force in the main longitudinal girders combined with local flexural compressive force in the longitudinal ribs, the longitudinal ribs, including the effective width of deck plate, shall be designed as independent beam columns assumed to be simply supported at each transverse beam.

10.16.3.4 Transverse flexure Transverse beams shall be proportioned so that

Mfb ≤ 1.00 Mrb November 2006

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where Mfb

= factored bending moment in the transverse beam at ULS

Mrb

= factored moment resistance of the transverse beam

10.16.4 Deflection At the SLS, the deflection due to live load plus the dynamic load allowance shall not exceed the following: (a) for the deck plate, 0.0033 times the spacing of rib webs; and (b) for longitudinal ribs and transverse beams, 0.001 times their respective spans. In addition, the extreme relative deflection between adjacent ribs shall not exceed 2.5 mm.

10.16.5 Girder diaphragms Diaphragms or cross-frames shall be provided at each support and shall be of sufficient stiffness and strength to transmit lateral forces to the bearings and to resist transverse rotation, displacement, and distortion. Intermediate diaphragms or cross-frames shall be provided at locations consistent with the analysis of the girders.

10.16.6 Design detail requirements 10.16.6.1 Minimum plate thickness The deck plate thickness, t, shall not be less than 14 mm or less than 0.04 times the larger spacing of rib webs.

10.16.6.2 Closed ribs The thickness of closed ribs shall not be less than 6 mm.

tr ( a ′ ) 3 tde h′

3

The parameter C =

shall not exceed 400

where tde

= effective thickness of the deck plate, taking into consideration the stiffening effect of the surfacing as specified in Clause 10.16.7

Closed ribs shall be sealed against entrance of moisture by continuous welds at the rib-to-deck plate interface and by welded diaphragms at their ends. Partial penetration groove welds between the webs of closed ribs and the deck plate shall not be less than 80%.

10.16.6.3 Deck and rib details Deck and rib splices shall be welded or mechanically fastened with high-strength bolts, using details consistent with Figure 10.5. The fatigue requirements of Clause 10.17 shall also be satisfied. Ribs shall extend continuously through cutouts in the webs of transverse floor beams, as shown in Figure 10.5. Welding of attachments, utility supports, lifting lugs, or shear connectors to the deck plates or the ribs shall require Approval.

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Single groove butt weld on permanent backing bar. Backing bar fillet welds continuous.

(a) Welded longitudinal field splice of deck plate a

Preferably no snipe in web

e 80% penetration

50

80% penetration

R

h

20

Grind ends of weld do not wrap around

c

Note: c > – h/3 (75 mm minimum).

(b) Intersection of closed ribs with floor beams

R

20

Edge of sidewalk

(c) Open ribs at floor beams 

Figure 10.5 Detailing requirements for orthotropic decks (See Clause 10.16.6.3.)

10.16.7 Wearing surface The wearing surface shall be considered an integral part of the orthotropic deck and shall be bonded to the top of the deck plate. The contribution of a wearing surface to the stiffness of the members of an orthotropic deck shall not be considered unless the structural and bonding properties are satisfactorily demonstrated over the design temperature range. If the contribution is considered, the required engineering properties of the wearing surface shall be specified on the Plans.

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For the purpose of design, the following requirements shall apply: (a) the long-term composite action between the deck plate and the wearing surface shall be demonstrated by both static and dynamic cyclic load tests; (b) the determination of force effects in the wearing surface and at the interface with the steel deck plate shall take into account the engineering properties of the wearing surface at anticipated extreme service temperatures; and (c) the wearing surface shall be assumed to act compositely with the deck plate whether or not the deck plate is designed on that basis.

10.17 Structural fatigue 10.17.1 General The FLS considered shall include direct live load effects, i.e., live load-induced fatigue, and the effects of local distortion within the structure, i.e., distortion-induced fatigue.

10.17.2 Live-load-induced fatigue 10.17.2.1 Calculation of stress range The stress range for load-induced fatigue shall be calculated using ordinary elastic analysis and the principles of mechanics of materials. A more sophisticated analysis shall be required only in cases not covered in Tables 10.7 and 10.8, such as major access holes and cutouts. Because the stress range shall be the algebraic difference between the maximum stress and minimum stress at a given location, only the stresses due to live load shall be considered. At locations where the stresses resulting from the permanent loads are compressive, load-induced fatigue shall be disregarded when the compressive stress is at least twice the maximum tensile live load stress. 

10.17.2.2 Design criteria For load-induced fatigue, except in bridge decks, each detail shall satisfy the requirement that 0.52CLfsr < Fsr where CL

= 1.0, except when W > 625 kN and the volume of heavy trucks prompting the use of a level of loading greater than that for CL-625 Trucks constitutes not more than the greater of 200 per day and 5% of the ADTT on the highway, CL = 0.20 + 500/W

fsr

= calculated fatigue stress range at the detail due to passage of the CL-W Truck, as specified in Clause 3.8.3.2

For load-induced fatigue in bridge decks, each detail shall satisfy the requirement that 0.62fsr  Fsr where fsr

= calculated fatigue stress range at the detail due to passage of a tandem set of 125 kN axles spaced 1.2 m apart and with a transverse wheel spacing of 1.8 m

10.17.2.3 Fatigue stress range resistance 10.17.2.3.1 Fatigue stress range resistance of a member or detail The fatigue stress range resistance of a member or a detail, Fsr , other than for shear studs or cables, shall be calculated as follows: Fsr = ( /Nc )1/3 Fsrt / 2

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where



= fatigue life constant pertaining to the detail category established in accordance with Clause 10.17.2.4 and specified in Table 10.4

Nc

= 365y Nd (ADTTf) where



y

=

design life (equal to 75 years unless otherwise specified by the Owner or Engineer)

Nd

=

number of design stress cycles experienced for each passage of the design truck, as specified in Table 10.5

ADTTf =

single-lane average daily truck traffic, as obtained from site-specific traffic forecasts. In lieu of such data, ADTTf shall be estimated as p (ADTT), where p shall be 1.0, 0.85, or 0.80 for the cases of one, two, or three or more lanes available to trucks, respectively, and ADTT shall be as specified in Table 10.6

10.17.2.3.2 Fatigue stress range resistance of fillet welds transversely loaded The fatigue stress range resistance, Fsr , of fillet welds transversely loaded shall be calculated as a function of the weld size and plate thickness, as follows: Fsr = Fsrc [(0.06 + 0.79D /t)/(0.64t1/6)] where Fsrc

= fatigue stress range resistance for Category C, as determined in accordance with Clause 10.17.2.3.1, based on no penetration of the weld root

D

= weld leg size, mm

t

= plate thickness, mm

Table 10.4 Fatigue life constants and constant amplitude threshold stress ranges (See Clauses 10.17.2.3.1 and 13.8.17.7.3.)

Detail category

Fatigue life constant, 

Constant amplitude threshold stress range, Fsrt, MPa

A B B1 C C1 D E E1 M164 M253

8190 × 109 3930 × 109 2000 × 109 1440 × 109 1440 × 109 721 × 109 361 × 109 128 × 109 561 × 109 1030 × 109

165 110 83 69 83 48 31 18 214 262

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Table 10.5 Values of Nd (See Clause 10.17.2.3.1.) Span length, L, 12 m

Span length, L, < 12 m

Simple-span girders Continuous girders Near interior support (within 0.1L on either side) All other locations Cantilever girders Trusses

1.0

2.0

1.5

2.0

1.0 5.0 1.0

2.0 5.0 1.0

Transverse members

Spacing  6 m

Spacing < 6 m

All cases

1

2

Longitudinal members

Table 10.6 Average daily truck traffic (See Clause 10.17.2.3.1.) Class of highway

ADTT

A B C D

4000 1000 250 50

10.17.2.4 Detail categories The detail categories shall be as specified in Tables 10.7 and 10.8. The following details shall be prohibited for use when cyclic loading is present: (a) partial penetration groove welds loaded transversely; and (b) cover plates attached to girder flanges using only fillet welds that are oriented transversely with respect to the direction of stress in the member.

10.17.2.5 Width-to-thickness ratios of transversely stiffened webs

The width-to-thickness ratios of transversely stiffened webs, h/w, shall not exceed 3150/ Fy unless a longitudinal stiffener is provided in accordance with Clause 10.10.7. In determining a width-to-thickness ratio, Fy may be replaced by the maximum compressive stress due to the factored ULS loads if the maximum shear at the FLS does not exceed Vr calculated in accordance with Clause 10.10.5.1, taking Ft = 0 and  s = 1.0.

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Canadian Highway Bridge Design Code

Table 10.7 Detail categories for load-induced fatigue (See Clauses 10.17.2.1 and 10.17.2.4 and Table 10.8.)

General condition

Situation

Plain members

Base metal With rolled or cleaned surfaces. Flame-cut edges with a surface roughness not exceeding 1000 (25 µm) as specified in CSA B95. Of unpainted weathering steel At net section of eyebar heads and pin plates

Built-up members

Groove-welded splice connections with weld soundness established by non-destructive testing and all required grinding in the direction of the applied stresses

Base metal and weld metal in components, without attachments, connected by one of the following: Continuous full-penetration groove welds with backing bars removed Continuous fillet welds parallel to the direction of applied stress Continuous full-penetration groove welds with backing bars in place Continuous partial-penetration groove welds parallel to the direction of applied stress Base metal at ends of partial-length cover plates With bolted slip-critical end connections Narrower than the flange (with or without end welds) or wider than the flange (with end welds) Flange thickness ≤ 20 mm Flange thickness > 20 mm Wider than the flange (without end welds) Base metal and weld metal at full-penetration groove-welded splices Of plates of similar cross-sections with welds ground flush With 600 mm radius transitions in width (with welds ground flush) With transitions in width or thickness (with welds ground to provide slopes not steeper than 1.0 to 2.5) CSA G40.21, 700Q or 700QT Other base metal grades With or without transitions with slopes not greater than 1.0 to 2.5, when weld reinforcement is not removed

Detail category

Illustrative example (see Figure 10.6)* 1, 2

A B E 3, 4, 5, 7 B B B1 B1 B

22

E E1 E1

7 7 7

B

8, 9

B

11 10, 10A

B1 B C

8, 9, 10, 10A

(Continued)

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Table 10.7 (Continued)

General condition

Situation

Longitudinally loaded groove-welded attachments

Base metal at details attached by full- or partial-penetration groove welds: When the detail length in the direction of applied stress is Less than 50 mm Between 50 mm and 12 times the detail thickness, but less than 100 mm Greater than either 12 times the detail thickness or 100 mm Detail thickness < 25 mm Detail thickness ≥ 25 mm With a transition radius, R, with the ends of welds ground smooth, regardless of detail length R ≥ 600 mm 600 mm > R ≥ 150 mm 150 mm > R ≥ 50 mm R < 50 mm With a transition radius, R, with ends of welds not ground smooth

Transversely loaded groove-welded attachments with weld soundness established by non-destructive testing and all required grinding transverse to the direction of stress

Fillet-welded connections with welds normal to the direction of stress

Fillet-welded connections with welds normal and/or parallel to the direction of stress

Base metal at detail attached by full-penetration groove welds with a transition radius, R, as follows: To flange, with equal plate thickness and weld reinforcement removed R ≥ 600 mm 600 mm > R ≥ 150 mm 150 mm > R ≥ 50 mm R < 50 mm To flange, with equal plate thickness and weld reinforcement not removed or to web R ≥ 150 mm 150 mm > R ≥ 50 mm R < 50 mm To flange, with unequal plate thickness and weld reinforcement removed R ≥ 50 mm R < 50 mm To flange, for any transition radius with unequal plate thickness and weld reinforcement not removed Base metal At details other than transverse stiffener to flange or transverse stiffener to web connections At the toe of transverse stiffener to flange and transverse stiffener to web welds Shear stress on the weld throat

Detail category

Illustrative example (see Figure 10.6)

C D

6, 18 18

E E1

18 18 12

B C D E E

12 12

B C D E C D E D E E

C

19

C1

6

E

16

(Continued)

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Table 10.7 (Concluded)

General condition

Situation

Longitudinally loaded fillet-welded attachments

Base metal at details attached by fillet welds When the detail length in the direction of applied stress is Less than 50 mm (or stud-type shear connectors are used) Between 50 mm and 12 times the detail thickness, but less than 100 mm Greater than either 12 times the detail thickness or 100 mm Detail thickness < 25 mm Detail thickness ≥ 25 mm With a transition radius, R, with the ends of welds ground smooth, regardless of detail length R ≥ 50 mm R < 50 mm With a transition radius, R, with ends of welds not ground smooth

Transversely loaded fillet-welded attachments with welds parallel to the direction of primary stress

Base metal at details attached by fillet welds With a transition radius, R, with end of welds ground smooth R ≥ 50 mm R < 50 mm With a transition radius, R, with ends of welds not ground smooth

Mechanically fastened connections

Base metal At gross section of high-strength bolted slip-critical connections, except axially loaded joints in which out-of-plane bending is induced in connected materials At net section of high-strength bolted non-slip-critical connections At net section of riveted connections

Detail category

Illustrative example (see Figure 10.6)

C

13, 15, 18, 20

D

18, 20 7, 16, 18, 20

E E1 12 D E E

12 12

D E E 17 B

B D

Anchor bolts and threaded parts

Tensile stress on the tensile stress area of the threaded part, including effects of bending

E

—

Hollow structural sections fillet-welded to base

Shear stress on fillet weld

E1

21

ASTM A 325 and ASTM A 325M bolts in axial tension

Tensile stress on area Ab

M164

—

ASTM A 490 and ASTM A 490M bolts in axial tension

Tensile stress on area Ab

M253

—

*The numbering of the diagrams in Figure 10.6 parallels the numbering used in Figure 2 of CAN/CSA-S16.

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Example 2

Example 1

or

CJP PJP

CJP

or

PJP or

Example 4

Example 3

CJP PJP

or

Gusset

or

Example 5

Example 6

Figure 10.6 Detail categories for load-induced fatigue (See Table 10.7.) (Continued)

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End weld optional

CJP

Example 8

Example 7

CJP CJP

CJP

Example 10 Example 9

CJP CJP

R = 600 mm

Example 10A

Example 11

Figure 10.6 (Continued) (Continued)

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or

CJP PJP

L

R CJP PJP

or or

L

R

Example 13

Example 12

L

Example 14 not used for bridges

Example 15

L > 100 mm

Example 16

Example 17

Figure 10.6 (Continued) (Continued)

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L L

CJP PJP

or or

Example 18

CJP PJP

or or

Example 19 L

Example 20

Example 21

Category B

End of weld

Example 22

Figure 10.6 (Concluded)

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Table 10.8 Detail categories for load-induced fatigue of orthotropic decks (See Clauses 10.17.2.1 and 10.17.2.4.) General condition

Situation

Detail category

Welded transverse deck plate splice

Single-groove butt weld on permanent backing bar. Backing bar fillet welds shall be continuous.

D

Bolted transverse deck plate splice

In unsymmetrical splices, effects of eccentricity shall be considered in calculating stress. See also “Mechanically fastened connections” in Table 10.7.

B

Welded rib splices

Double-groove welds. The height of weld convexity shall not exceed 20% of weld width. Weld runoff tabs shall be used and subsequently removed. Plate edges shall be ground flush in the direction of stress.

C

Welded rib splice with backing bar

Single-groove butt weld with permanent backing bar. Backing bars at fillet welds shall be continuous.

E

Illustrative example

(Continued)

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Table 10.8 (Concluded) General condition

Situation

Detail category

Welded rib splice without backing bar

Single-groove butt weld without backing bar

E1

Rib intersection with floor beam

Axial stress in rib wall at the lower end of rib to floor beam weld

D

Deck plate to floor beam connection

Deck plate stress parallel to floor beam at deck to floor beam junction

D

Floor beam web at cutout

Vertical stress in floor beam web at floor beam cutout at the bottom of rib. f = stress in floor beam web due to bending moment, VHh, where VH = VLL+I (a + e) Q/I and Q and I are properties of the floor beam cross-section at Section 1-1.

D

Illustrative example

1 e

Q

VH

h

f

1

10.17.2.6 Fatigue resistance of high-strength bolts loaded in tension High-strength bolts subjected to tensile cyclic loading shall be pretensioned to the minimum preload specified in Clause 10.24.6.3. Connected parts shall be arranged so that prying forces are minimized. The calculated prying force shall not exceed 30% of the externally applied load.

10.17.2.7 Fatigue resistance of stud shear connectors Stud shear connectors shall be designed for the following stress range, rs : V Qs t rs = 0.52CL sc Asc It n



where CL = 1.0, except when W > 625 kN and the volume of heavy trucks prompting the use of a level of loading greater than that for CL-625 Trucks constitutes not more than the greater of 200 per day and 5% of the ADTT on the highway, CL = 0.20 + 500/W = range of design shear force at the section along the length of the beam where the fatigue Vsc resistance of the shear connectors is being evaluated, N Q = first moment of area of the transformed section at the interface between the concrete slab and the steel section, mm3 s = shear stud group spacing, mm = cross-sectional area of a shear stud, mm2 Asc n = number of shear studs in the group at the cross-section being evaluated = moment of inertia of the transformed composite section about the axis of bending, mm4 It Fatigue Category D shall be used to evaluate the fatigue resistance of stud shear connectors. October 2011 (Replaces p. 499, May 2010)

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When stud shear connectors are not provided in negative moment regions, additional connectors, Na in number, shall be provided at each location of contraflexure, where

Na = 0.52CL

Ar fsr Z sr

where Zsr

= the allowable range of interface shear in an individual shear connector, given as

(

Z sr = 721× 109 Nc

)

13

Asc ≥ 24Asc

where Nc

= number of cycles as specified in Clause 10.17.2.3

These additional connectors shall be placed within a distance equal to one-third of the effective slab width on each side of the point of dead load contraflexure.

10.17.2.8 Fatigue resistance of cables 10.17.2.8.1 Suspension cables and hangers Cables and hangers used in suspension bridge construction need not be designed for fatigue, unless, in the judgment of the Engineer, special fatigue provisions are required.

10.17.2.8.2 Cable-stays and cable-stayed bridge tie-downs 10.17.2.8.2.1 Inspectable stays The fatigue stress range for cable-stays and tie-downs that are replaceable without significant loss of function of the bridge, and in which wire breaks can be detected in service, shall not exceed the fatigue stress resistance established by test. An acceptable test is a test of cable and sockets in which the stress range is applied for 2 000 000 cycles and, at the end of which, the test stay has at least 0.95 of its specified breaking strength. The lowest stress range of three successful tests shall be taken as the fatigue stress range resistance. For the purpose of this Clause, secondary (bending) stresses shall be calculated, but only secondary stresses exceeding 50 MPa shall be added to the primary (tension) stress to derive the test fatigue stress range.

10.17.2.8.2.2 Non-inspectable or non-replaceable stays The fatigue stress range resistances for cable stays and tie-downs in which wire breaks cannot be detected while they are in service, or for cable stays and tie-downs that cannot be readily replaced, shall not exceed 0.75 of the fatigue stress range resistance established by test.

10.17.3 Distortion-induced fatigue 10.17.3.1 General When members designed in accordance with Clause 10.17.2 for load-induced fatigue are provided with interconnection components such as diaphragms, cross-bracing, and lateral bracing, both the members and the interconnection components shall be examined for distortion-induced fatigue. Wherever practicable, elements of the primary member shall be fastened to the interconnection member unless otherwise Approved. The requirements for controlling web buckling and flexing of girder webs specified in Clause 10.17.3.2.2 shall apply.

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10.17.3.2 Connection of diaphragms, cross-frames, lateral bracing, and floor beams 10.17.3.2.1 Connection to transverse elements Unless otherwise Approved, the connections of diaphragms, including internal diaphragms, cross-frames, lateral bracing, floor beams, etc., to main members shall be made using transverse connection plates that are welded or bolted to both the tension and compression flanges of the main member. If transverse stiffeners of the main members form part of the connection, they shall be similarly connected. In straight non-skewed bridges, the connections shall be designed to resist a factored horizontal force of 90 kN unless a more exact value is determined by analysis.

10.17.3.2.2 Connection to lateral elements If connections of diaphragms, including internal diaphragms, cross-frames, lateral bracing, floor beams, etc., are to be made to elements that are parallel to the longitudinal axis of the main member, the lateral connection plates shall be attached to both the tension and compression flanges of the main member. Where this is not practicable, then lateral connection plates shall be located as follows: (a) Transversely stiffened girders: where lateral connection plates are fastened to a transversely stiffened girder, the attachment shall be located at a vertical distance not less than one-half the flange width from the flange. If located within the depth of the web, the lateral connection plate shall be centred with respect to the transverse stiffener, whether or not the stiffener and the connection plate are on opposite sides of the web. If the lateral connection plate and the transverse stiffener are located on the same side of the web, the plate shall be attached to the stiffener. Transverse stiffeners at locations where lateral connection plates are attached shall be continuous between the flanges and shall be fastened to them. Bracing members attached to the lateral connection plates shall be located so that their ends are at least 100 mm from the face of the girder web and the transverse stiffener. (b) Transversely unstiffened girders: lateral connection plates may be fastened to a transversely unstiffened girder, provided that the attachment is located a vertical distance not less than one-half the flange width or 150 mm from the flange. Bracing members attached to the lateral connection plates shall be located so that their ends are at least 100 mm from the face of the girder web.

10.17.4 Orthotropic decks Distortion-induced fatigue shall be minimized through appropriate detailing in accordance with Clause 10.16.6. The stress ranges for live-load-induced fatigue shall be as specified in Clause 10.17.2.

10.18 Splices and connections 10.18.1 General 10.18.1.1 General design considerations Splices and connections shall be designed at the ULS for the larger of (a) the calculated forces at the splice or connection; or (b) 75% of the factored resistance of the member, such resistance to be based on the condition of tension, compression, bending, or shear that governed selection of the member. Except for handrails and non-load-carrying components, connections shall contain at least two 16 mm diameter high-strength bolts or equivalent welds.

10.18.1.2 Alignment of axially loaded members When the centroidal axes of axially loaded members meeting at a joint do not intersect at a common point, the effect of joint eccentricity shall be considered.

May 2010 (Replaces p. 501, November 2006)

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10.18.1.3 Proportioning of splices and connections Splices and connections shall be designed for all of the forces, including axial, bending, and shear forces, that can occur in the connected components (allowing for any eccentricity of loading). Where the fatigue requirements of Clause 10.17 govern the design, the connections shall be designed to the same requirements.

10.18.1.4 Compression members finished to bear At the ends of compression members that are finished to bear, splice material and connecting bolts or welds shall be arranged to hold all of the components in place and shall be proportioned to resist not less than 50% of the force effects at the ULS. 

10.18.1.5 Beam and girder connections End connections for beams and girders that are proportioned to resist vertical reactions only shall be detailed to minimize the flexural end restraint, except that inelastic action in the connection at the SLS shall be permitted in order to accommodate the end rotations of unrestrained simple beams. The connections of beams and girders subject to both reaction shear and end moment due to rigid, continuous, or cantilever construction shall be proportioned for the loads at the ULS. Axial forces, if present, shall also be considered. Coping of flanges at connections may be used for secondary members in bridges with straight girders. Coping of flanges at connections of floor beams and main girders shall not be permitted. Blocks shall be used instead of copes whenever possible.

10.18.2 Bolted connections 10.18.2.1 General All high-strength bolts shall be pretensioned in accordance with Clause 10.24.6.3.

10.18.2.2 Bolts in tension 10.18.2.2.1 Tensile resistance at the ultimate limit states The factored tensile resistance, Tr , developed by the bolts in a bolted joint subject to tension, Tf , shall be taken as Tr = 0.75 b n Ab Fu where Fu

= specified ultimate tensile strength of the bolt material

Bolts in tension shall be proportioned to resist the factored tensile force, Tf , taken as the sum of the factored external load and any additional tension resulting from prying action produced by the deformations of the connected parts, but neglecting bolt pretension.

10.18.2.2.2 Tensile resistance at the fatigue limit state High-strength bolts subjected to tensile cyclic loading shall meet the requirements of Clause 10.17.2.6.

10.18.2.3 Bolted joints in shear 

10.18.2.3.1 General Bolted joints required to resist shear between the connected parts shall be designed as slip-critical connections at FLS and SLS, except for connections of bracing members in straight girder bridges and connections not subjected to stress reversal.

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10.18.2.3.2 Slip resistance at the service load levels The slip resistance, Vs , of a bolted joint in a slip-critical connection subjected to shear, V, shall be taken as Vs = 0.53c1ks mnAb Fu where ks

= mean slip coefficient determined in accordance with Table 10.9 or by Approved tests

c1

= coefficient that relates the specified initial tension and mean slip to a 5% probability of slip for bolts installed by turn-of-nut procedures, as specified in Table 10.9

For installation using other procedures, different values of c 1 apply. In long-slotted holes, the shear resistance shall be taken as 0.75Vs . A slip-critical connection shall also satisfy the shear and bearing criteria at the ULS.

Table 10.9 Values of ks and c1



(See Clauses 10.18.2.3.2 and 10.24.6.2.) Contact surface of bolted parts Class

Description

ks

c1 (ASTM A 325 and ASTM F 1852)

c1 (ASTM A 490 and ASTM F 2280)

A

Clean mill-scale or blast cleaned with Class A coatings

0.33

0.82

0.78

B

Blast-cleaned surfaces or blast-cleaned surface with Class B coatings

0.50

0.90

0.85

C

Hot-dip galvanized with hand wire-brushed surfaces

0.40

0.90

0.85

Note: Class A and B coatings are those coatings that provide a mean slip-coefficient of not less than 0.33 and 0.50, respectively. Values of c1 for a 5% probability of slip for values of ks other than those specified in this Table shall be determined by an Approved means.



10.18.2.3.3 Shear resistance at the ultimate limit states The factored shear resistance of a bolted joint subject to a shear force, Vf , shall be taken as the lesser of (a) the bearing resistance, Br , of the plate adjacent to the bolts, as follows: Br

= 3 br ntdFu

where Fu = ultimate strength of the plate  br = 0 . 8 0 (b) the shear resistance, Vr , of the bolts, as follows: Vr

= 0.60 b nmAb Fu

where Fu

= ultimate strength of the bolt material

For axially loaded lap splices with shear transfer length > 760 mm: Vr = 0.50 b nmAb Fu If any bolt threads are intercepted by a shear plane, the factored shear resistance of the joint shall be taken as 0.7Vr .

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10.18.2.4 Bolts in shear and tension 10.18.2.4.1 Resistance at the serviceability limit states Bolts in a connection subjected to loads that cause shear, V, and tension, T, shall satisfy the following relationship:

V 1.9T + ≤ 1 .0 Vs nAbFu The requirements of Clause 10.18.2.3.2 shall also be met.

10.18.2.4.2 Resistance at the ultimate limit states A bolt that is required to resist a tensile force and a shear force at the ULS shall satisfy the following relationship: 2

2

⎡Vf ⎤ ⎡Tf ⎤ ⎢ ⎥ + ⎢ ⎥ ≤ 1.0 ⎣Vr ⎦ ⎣Tr ⎦

10.18.3 Welds 10.18.3.1 General Welding design shall comply with CSA W59, except as otherwise specified in Clause 10.18.3. The matching electrode classifications for CSA G40.21 and CSA W59 steels shall be as specified in Table 10.10.

Table 10.10 Matching electrode classifications for CSA G40.21 and CSA W59 steels (See Clause 10.18.3.1.) Matching  electrode* 430 490 550 620 820

CSA G40.21 grade 260

300

350

380

X X

X† X

X‡

X

400

480

700

X‡ X X

*The number indicates the tensile strength of the weld metal in megapascals, as indicated in the electrode classification number. †For hollow structural steel sections only. ‡For uncoated applications using “A” or “AT” steels, where the deposited weld metal is to have atmospheric corrosion resistance and/or corrosion characteristics similar to those of the base metal, the requirements of Clauses 5.2.1.4 and 5.2.1.5 of CSA W59 shall apply.

10.18.3.2 Shear 10.18.3.2.1 Complete and partial joint penetration groove welds The factored shear resistance,Vr , shall be taken as the lesser of (a) for base metal: Vr = 0.67 w Am Fu

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(b) for weld metal: Vr = 0.67 w Aw Xu 

10.18.3.2.2 Fillet welds The factored resistance for tension- or compression-induced shear, Vr , shall be taken as the lesser of (a) for base metal: Vr = 0.67 w Am Fu (b) for weld metal: Vr = 0.67 w Aw Xu (1.00 + 0.50 sin1.5) Rw where



= angle between the axis of the weld segment and the line of action of the applied force (e.g., 0° for a longitudinal weld and 90° for a transverse weld)

Rw

= strength reduction factor. = 1.0 for the weld segment with the largest  = 0.85 for the other weld segments

Note: It is a conservative simplification to take the bracketed quantity in Item (b) equal to 1.0.

10.18.3.3 Tension normal to the weld axis Complete joint penetration groove welds shall be made with matching electrodes. The factored tensile resistance shall be taken as that of the base metal.

10.18.3.4 Compression normal to the weld axis Complete and partial joint penetration groove welds shall be made with matching electrodes. The factored compressive resistance shall be taken as that of the effective area of the base metal in the joint. For partial penetration groove welds, the effective area in compression shall be taken as the nominal area of the fusion face normal to the compression plus the area of the base metal fitted to bear.

10.18.3.5 Hollow structural sections The provisions of Appendix L of CSA W59 should be applied to hollow structural sections. Note: Use of these provisions is strongly recommended.

10.18.4 Detailing of bolted connections 10.18.4.1 Contact of bolted parts Bolted parts shall fit together solidly when assembled and shall not be separated by gaskets or any other interposed compressible material.

10.18.4.2 Hole size The nominal diameter of a hole shall not be more than 2 mm greater than the nominal bolt size, except that where shown on the Plans, oversize or slotted holes may be used with high-strength ASTM A 325 or ASTM A 490 bolts 5/8 in or larger in diameter, or with ASTM A 325M or ASTM A 490M bolts 16 mm or larger in diameter. Joints with oversize or slotted holes shall meet the following requirements: (a) Oversize holes shall not be more than 4 mm larger than bolts 22 mm or less in diameter, not more than 6 mm larger than bolts 24 mm in diameter, and not more than 8 mm larger than bolts 27 mm or more in diameter. Oversize holes used in any plies of connections shall be provided with hardened washers under heads or nuts adjacent to plies containing oversize holes.

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(b) Short slotted holes shall not be more than 2 mm wider than the bolt diameter and shall not have a length that exceeds the oversize diameter requirements of Item (a) by more than 2 mm. When used in any plies of connections, hardened washers shall be provided under heads or nuts adjacent to plies containing slotted holes. (c) Long slotted holes shall not be more than 2 mm wider than the bolt diameter and shall not be greater than 2.5 times the bolt diameter. They shall also comply with the following requirements: (i) when the slotted hole is normal to the direction of the load, the shear resistance shall be as specified in Clause 10.18.2.3.2; (ii) they shall be used in only one of the connected parts at a given faying surface; and (iii) structural plate washers or a continuous bar not less than 8 mm thick shall cover long slots that are in the outer plies of joints after installation. (d) When ASTM A 490 or ASTM A 490M bolts larger than 26 mm in diameter are used in oversize or slotted holes in outer plies, the hardened washers shall be at least 8 mm thick and comply with ASTM F 436. (e) The requirements for the nominal diameter of a hole shall not preclude the use of the following bolt diameters and hole combinations: (i) a 3/4 in bolt or an M20 bolt in a 22 mm diameter hole; (ii) a 7/8 in bolt or an M22 bolt in a 24 mm diameter hole; and (iii) a 1 in bolt or an M24 bolt in a 27 mm diameter hole.

10.18.4.3 Coatings The faying surfaces of slip-critical connections shall be shown on the Plans as coated or uncoated. Where faying surfaces are to be coated, one of the following processes shall be used: (a) hot-dip galvanizing, provided that the faying surfaces are hand wire-brushed after galvanizing and before assembly; (b) sprayed-zinc coatings, applied in accordance with CSA G189; or (c) other Approved materials and methods, provided that these have been tested in accordance with the Specification for Structural Joints Using ASTM A325 or A490 Bolts issued by the Research Council on Structural Connections.

10.18.4.4 Bolt spacing The minimum distance between centres of bolt holes shall not be less than 3 bolt diameters wherever practicable and never less than 2.7 diameters. The maximum bolt spacing shall be governed by the requirements for sealing or stitching specified in Clauses 10.18.4.5 to 10.18.4.7.

10.18.4.5 Sealing bolts For sealing bolts, the pitch, p, between bolts on a single line adjacent to a free edge of an outside plate or shape shall be equal to or less than (100 + 4t)  180 When a second line of fasteners is uniformly staggered with those in the line adjacent to the free edge, at a gauge less than 40 + 4t therefrom, the staggered pitch, p, in two such lines considered together shall be equal to or less than

⎡ 3g ⎤ 100 + 4t − ⎢ ⎥ ≤ 180 ⎣d ⎦ or one-half the requirement for a single line, whichever is greater.

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.18.4.6 Stitch bolts Unless closer spacing is required for transfer of load or for sealing inaccessible surfaces, the longitudinal spacing in-line between intermediate bolts in built-up compression members shall not exceed 12t. The gauge, g, between adjacent lines of bolts shall not exceed 24t. The staggered pitch between two adjacent lines of staggered holes shall not exceed

⎡ 3g ⎤ p ≤ 15t − ⎢ ⎥ ≤ 12t ⎣8⎦ The pitch for tension members shall not exceed twice that specified for compression members. The gauge for tension members shall not exceed 24t.

May 2010

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Canadian Highway Bridge Design Code

10.18.4.7 Stitch bolts at the ends of compression members All component parts that are in contact with one another at the ends of built-up compression members shall be connected by bolts spaced longitudinally not more than four diameters apart for a distance of 1.5 times the width of the member from the end.

10.18.4.8 Minimum edge distance The minimum edge distance from the centre of a bolt hole to any edge shall be that specified in Table 10.11.

Table 10.11 Minimum edge distance for bolt holes (See Clauses 10.18.4.8 and 10.18.4.9.) Bolt designation and diameter, in

Minimum edge distance at sheared edge, mm

Minimum edge distance at rolled or gas-cut edge, mm*

M16 (5/8) M20 (3/4) M22 (7/8) M24 (1) M27 (1-1/8) M30 (1-1/4) M36 (over 1-1/4)

28 32 38† 44† 51† 57 1.75 × diameter

22 25 28 32 38 41 1.25 × diameter

*Edge distances in this column may be decreased by 3 mm when the hole is at a point where calculated stress under factored loads is not greater than 0.3 times the yield stress. †At the ends of beam framing angles, the minimum distance shall be 32 mm.

10.18.4.9 Minimum end distance When tension member connections have more than two bolts in line parallel to the direction of load, the minimum end distance measured from the centre of the end fastener to the nearest end of the connected part shall not be less than the applicable edge distance value specified in Table 10.11. In connections with one or two bolts in the line of the load, the end distance shall not be less than 1.5 bolt diameters.

10.18.4.10 Maximum edge or end distance The maximum distance from the centre of a bolt to the nearest edge of connected components shall be the lesser of eight times the thickness of the outside connected component and 125 mm.

10.18.4.11 Sloping surfaces Bevelled washers shall be used under the head or nut in accordance with Clause 10.24.6.5 when the two bearing surfaces are not parallel.

10.18.4.12 Fillers When load-carrying fasteners pass through fillers with a total thickness greater than 6 mm, the fillers shall be extended beyond the splice material and the filler extension shall be secured by sufficient fasteners to distribute the total force in the member at the ULS uniformly over the combined section of the member and filler. Alternatively, an equivalent number of fasteners shall be included in the connection without extending the filler. Fillers shall not consist of more than two plates unless a greater number of plates is Approved.

November 2006

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10.18.5 Connection reinforcement and stiffening 10.18.5.1 General Connections shall be made by suitably designed pins, by direct welding of one member to another, or by bolts or welds with gusset plates.

10.18.5.2 Gusset plates The tensile resistance (including block tearout) and the compressive resistance of gusset plates shall be assessed as appropriate. The factored shear resistance, Vr , of the gusset plate shall be taken as Vr = 0.50φ s Ag Fy on the gross section = 0.50φ s An Fu on the net section where An

= minimum cross-sectional area subjected to shear, allowing for holes if present Re-entrant cuts, except curves made for appearance, shall be avoided as far as practicable. The

unsupported edge of a gusset plate shall be stiffened if its length exceeds 930/ Fy times its thickness.

10.18.5.3 Moment connections 10.18.5.3.1 General For beams rigidly framed to the flange of an H-shaped member, stiffeners shall be provided on the web of the H-shaped member in accordance with Clauses 10.18.5.3.2 to 10.18.5.3.5.

10.18.5.3.2 Stiffeners opposite compression flanges Stiffeners shall be provided opposite the compression flange of the beam when one of the following factored bearing resistances, Br , is exceeded: (a)

⎡ ⎡ t ⎤ ⎡w ⎤ Br = 300fs w c2 ⎢1+ 3 ⎢ b ⎥ ⎢ c ⎥ ⎢ ⎣ hc ⎦ ⎣ tc ⎦ ⎣

1.5 ⎤

(b)

Br = fs w c (tb + 5k ) Fyc <

(c)

⎡ 640 000 ⎤ M ⎥ w c (tb + 5k ) < f (for H-shaped members with Class 3 webs) Br = fs ⎢ 2 d ⎢⎣ (hc / w c ) ⎥⎦

⎥ ⎥ ⎦

Fyc tc wc

<

Mf d

Mf d

10.18.5.3.3 Stiffeners opposite tension flanges Stiffeners shall be provided opposite the tension flange of the beam when the following factored tensile resistance, Tr , is exceeded:

Tr = 7fs Fyc tc2 <

Mf d

10.18.5.3.4 Stiffener force The stiffener or pair of stiffeners opposite either beam flange shall be proportioned for a factored force at the ULS of

Fst =

Mf − Br d

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10.18.5.3.5 Stiffener connection and stiffener length Stiffeners shall be connected so that the force in the stiffener is transferred through the stiffener connection. When beams frame to one side of a column only, the stiffeners need not be longer than one-half the depth of the column.



10.19 Anchor rods 10.19.1 General Anchors provided to connect the superstructure to the substructure shall be proportioned to withstand the effect of uplift forces, bending moments, and shear at the ULS determined in accordance with Sections 3 and 5. Anchor rods for bearing assemblies shall have a minimum diameter of 30 mm and a minimum embedment length of 300 mm. The compression resistance of the concrete, the anchorage of rods, the shear resistance between the baseplate and substructure, and the moment resistance of anchorage systems shall be determined in accordance with Clause 8.16.7.

10.19.2 Anchor rod resistance 10.19.2.1 Tension The factored tensile resistance, Tr , of an anchor rod shall be taken as Tr = b As Fu where As

= tensile stress area

π (d − 0.938p )2 4 where p = pitch of threads, mm =

10.19.2.2 Shear The factored shear resistance, Vr , of an anchor rod shall be taken as Vr = 0.60 b n Ab Fu but not be greater than the lateral bearing resistance specified in Clause 8.16.7.3. When rod threads are intercepted by the shear plane, the factored resistance shall be taken as 0.70Vr .

10.19.2.3 Combined tension and shear An anchor rod required to develop resistance to both tension and shear shall be proportioned so that 2

2

⎡Vf ⎤ ⎡Tf ⎤ ⎢ ⎥ + ⎢ ⎥ ≤ 1.0 ⎣Vr ⎦ ⎣Tr ⎦ where Vr

= portion of the total shear per rod transmitted by bearing of the anchor rods on the concrete, as required by Section 8

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10.19.2.4 Combined tension and bending Anchor rods required to develop resistance to both tension and bending shall be proportioned to meet the requirements of Clause 10.8.3. The tensile and moment resistances, Tr and Mr , respectively, shall be based on the properties of the cross-section at the critical section; Mr shall be taken as  bS Fy .

10.20 Pins, rollers, and rockers 10.20.1 Bearing resistance The factored bearing resistance, Br , developed by a component or portion of a component subjected to bearing shall be calculated as follows: (a) on the contact area of machined, accurately sawn, or fitted parts and on the bearing area of pins: Br = 1.50 s Fy A where the bearing area of pins is taken as the pin diameter multiplied by the thickness of the connected parts; and (b) on expansion rollers or rockers:

⎡ R ⎤ Br = 0.00026fs ⎢ 1 ⎥ LFy2 R ⎢ 1− 1 ⎥ ⎢⎣ R2 ⎥⎦ where Fy

= specified minimum yield point of the weaker part in contact

10.20.2 Pins 10.20.2.1 Bending resistance

The factored bending resistance of a pin shall be taken as Mr =  sS Fy .

10.20.2.2 Shear resistance

The factored shear resistance of a pin shall be taken as Vr = 0.60 s A Fy .

10.20.2.3 Combined bending and shear Sections of pins subject to both bending and shear shall be proportioned so that 3

Mf ⎡Vf ⎤ + ⎢ ⎥ ≤ 1.0 Mr ⎣Vr ⎦ 

10.20.2.4 Pin connection details Pins shall be of sufficient length to ensure full bearing of all parts connected to the turned body of the pin. They shall be secured in position by hexagonal recessed nuts or by hexagonal solid nuts with washers or, if the pins are bored, by throughrods with recessed cap washers. Pin nuts shall be malleable steel castings or steel and shall be secured by cotter pins in the screw ends or with locknuts. Pins shall be located so as to minimize the force effects due to eccentricity. Pin plates shall contain sufficient welds or fasteners to distribute their portion of the pin load to the full cross-section of the component with due consideration given to the effects of eccentricity.

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10.21 Torsion 10.21.1 General Members and their connections subjected to torsion shall have sufficient strength and rigidity to resist the torsional moments and forces in addition to other moments and forces. The torsional deformations at the SLS shall be within acceptable limits.

10.21.2 Members of closed cross-section 10.21.2.1 Torsional resistance The factored torsional resistance, Qr , taking the warping constant, Cw , to be zero, shall be calculated as

2

Qr =

3

fs Fy A ′t

where t

= minimum thickness of material, provided that the width-to-thickness ratios of elements are

(a) for flat plate elements: b/t  1100/ Fy (b) for circular hollow sections (or multi-sided hollow sections that approximate a circle): D / t  18 000/ Fy When a width-to-thickness ratio exceeds a ratio specified in Item (a) or (b), as applicable, the torsional resistance shall be calculated using an elastic analysis.

10.21.2.2 Combined axial compression, flexure, and torsion Members of closed cross-section subject to combined axial compression, flexure, and torsion shall be proportioned so that

Cf + Cr

2

⎡Q ⎤ Mf + ⎢ f ⎥ ≤ 1.0 ⎡ Cf ⎤ ⎣ Qr ⎦ Mr ⎢1− ⎥ ⎣ Ce ⎦

where Cr is as specified in Clause 10.9.3, Mr is as specified in Clause 10.10, and Qr is as specified in Clause 10.21.2.1.

10.21.2.3 Reinforcement of cut-outs Members with cut-outs whose torsional design is based on the cross-sectional properties of the closed cross-section shall be detailed as follows: (a) cut-outs shall have semicircular ends; (b) the width of a cut-out shall not exceed 0.17 times the circumference of the member; (c) a stiffener shall be provided around the perimeter of the cutout and welded to develop the full cross-section of the wall. The stiffener shall have a cross-sectional area, A, of

(

A =L t/ 3

)

where L

= length of the cut-out measured parallel to the longitudinal axis of the member

t

= thickness of the wall of the member

(d) the width-to-thickness ratio of the outstanding portions of the stiffener shall not exceed 170/ Fy . May 2010 (Replaces p. 511, November 2006)

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10.21.3 Members of open cross-section 10.21.3.1 St. Venant torsional constant The St. Venant torsional constant shall be calculated as

J=S

bt 3 3

where b

= length of the plate element

t

= thickness of the plate element The width-to-thickness ratios of elements shall meet the requirements of Clause 10.9.2.

10.21.3.2 Warping constant The warping constant, Cw , shall be calculated as follows: (a) for a doubly symmetric I-shaped section:

Cw =

l y h2

4 (b) for a monosymmetric I-shaped section: Cw =

h2l y 1l y 2

(l y 1 + l y 2 )

where Iy

= moment of inertia about the minor axis

Iy1 , Iy2 = moment of inertia of the upper and lower flanges, respectively, about the y-axis of symmetry (c) for a closed rectangular section: 2

⎡d ⎤ Cw = 2lf ⎢ ⎥ + 2Iw ⎣2⎦ where If

=

b3t 12

Iw

=

d 3w 12

⎡b ⎤ ⎢⎣ 2 ⎥⎦

2

10.21.3.3 Torsional resistance The factored torsional resistance of members of open cross-section shall be calculated based on accepted principles of elastic torsional analysis, taking into account the St. Venant and warping torsional resistance as a function of the loading and restraint conditions.

10.21.3.4 Combined bending and torsion For I-shaped members subject to torsion or combined bending and torsion, the maximum combined normal stress due to warping torsion and bending at SLS loads, as determined by an elastic analysis, shall not exceed Fy .

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

10.22 Steel piles 10.22.1 General The structural design of steel piles shall be in accordance with this Section. The geotechnical design shall be in accordance with Section 6.

10.22.2 Resistance factors The resistance factor to be used when calculating the factored axial compressive resistance for piles under axial compression alone in accordance with Clause 10.22.3.1 shall be 0.70. The factor given in Clause 6.8.8.5 shall also apply unless the pile is not driven into the soil but rather lowered into a pre-augered hole. When calculating the resistance of the pile above the point of fixity, the resistance factors for coincident axial compression and bending shall be 0.70 for compression and 0.95 for flexure.

10.22.3 Compressive resistance 10.22.3.1 Axial compression For piles under axial compression alone, the factored axial compressive loads shall not exceed the factored compressive resistance specified in Clause 10.9.3.

10.22.3.2 Combined axial compression and bending Piles under coincident axial compression and bending shall satisfy the following: (a) The factored axial compressive loads shall not exceed the axial compressive resistance of the pile, as calculated under Clause 10.22.3.1. (b) The coincident axial compressive and flexural loads and resistance of the pile above the point of fixity shall satisfy the requirements of Clause 10.9.4.

10.22.4 Unsupported length For piles that are subjected to axial compression alone and are fully embedded in soil, the unsupported length, L, shall be taken as zero. If the pile extends above the ground surface in air or water, or is subjected to combined axial compression and bending, the unsupported length of the pile shall include the length of the pile above the soil, if any, plus an embedded depth to fixity.

10.22.5 Effective length factor The effective length factor, K, shall be determined on the basis of the restraint provided by the soil, the pile cap, the structure, and the substructure, as specified in Section 6.

10.22.6 Splices Splices shall be proportioned to develop the full cross-sectional strength of the pile.

10.22.7 Welding Welding shall be in accordance with Clause 10.24.5.

10.22.8 Composite tube piles For composite tube piles, the applicable requirements of Clause 10.9.5 shall be met.

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10.23 Fracture control 10.23.1 General Fracture control shall be considered throughout material selection and structural design. Consideration shall be given to (a) designation of fracture-critical and primary tension members; (b) the level of quality control, inspection, and monitoring during fabrication; (c) the likelihood of crack initiation and crack growth; (d) selection of steel and welding consumables with appropriate toughness; and (e) controlling stress concentrations and improper alignment.

10.23.2 Identification The components identified as fracture-critical members and primary tension members shall be clearly identified in the Plans. Shop drawings shall identify the extent of fracture-critical and primary tension members. Attachments longer than 100 mm in the direction of tension and welded to the tension zone of a fracture-critical or primary tension member shall be treated as part of that member. For each component of a fracture-critical or primary tension member, records shall be kept to identify the heat number of the material and its corresponding mill test certificate. The fracture-toughness and welding requirements of Clauses 10.23.3 to 10.23.5 shall apply only to members designated as fracture-critical and primary tension members.

10.23.3 Fracture toughness 10.23.3.1 General The Charpy V-notch requirements specified in Clause 10.23.3 shall apply only to standard full-size specimens. For plates from 8 to 11 mm thick, subsize specimens with adjusted energy levels may be used, as permitted by CSA G40.20. The requirements of Clause 10.23.3 shall apply to both bolted and welded construction.

10.23.3.2 Fracture-critical members For fracture-critical members, Charpy V-notch tests shall be specified on a per plate frequency, as defined in CSA G40.20/G40.21. The steel shall meet the impact energy requirements specified in Table 10.12.

10.23.3.3 Primary tension members For primary tension members, Charpy V-notch tests shall be specified on a per heat frequency, as defined in CSA G40.20/G40.21. The steel shall meet the impact energy requirements specified in Table 10.13.

10.23.3.4 Service temperature The applicable minimum service temperature, Ts , shall be the minimum daily mean temperature in Figure A3.1.2. 

10.23.3.5 Weld metal toughness For fracture-critical and primary tension members, the weld metal shall meet the impact energy requirements of (a) Clause 10.23.4; and (b) Tables 10.14A and 10.14B, respectively.

10.23.3.6 Steel for permanent backing bars Steel for permanent backing bars shall meet the requirements of Clause 5.5.1.1 of CSA W59 and shall meet the Charpy impact energy requirements of Table 10.12 or 10.13, as applicable.

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Table 10.12 Impact test temperatures and Charpy impact energy requirements for fracture-critical members (See Clauses 10.23.3.2, 10.23.3.6, and 10.23.4.4.)

Minimum average energy, J

CSA G40.21 grade

Test temperature, Tt , °C, for minimum service temperature, Ts, °C Ts –30

–30 > Ts – 60

Ts < – 60

–10 –10 –10 –10

–30 –30 –30 –30

–50 –50 –50 –50

–10 –20

– 40 – 40

– 60 – 60

Commonly used steels 260 WT 300 WT 350 WT and AT 400 WT and AT

20 20 27 27

Steels requiring Approval 480 WT and AT 700 QT

40 50

Table 10.13 Impact test temperatures and Charpy impact energy requirements for primary tension members (See Clauses 10.23.3.3, 10.23.3.6, and 10.23.4.4.)

CSA G40.21 grade

Minimum average energy, J

Test temperature, Tt , °C, for minimum service temperature, Ts, °C Ts –30

–30 > Ts – 60

Ts < – 60

0 0 0 0

–20 –20 –20 –20

–30 –30 –30 –30

–10 –20

–30 – 40

– 40 –50

Commonly used steels 260 WT 300 WT 350 WT and AT 400 WT and AT

20 20 27 27

Steels requiring Approval 480 WT and AT 700 QT

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Table 10.14A Impact test temperatures and Charpy impact energy requirements for weld metal in fracture-critical members (See Clauses 10.23.3.5 and 10.23.4.2–10.23.4.5.)

Base metal CSA G40.21 grade

Minimum average energy, J

260 WT 300 WT 350 WT and AT 400 WT and AT 480 WT and AT 700 QT

20 20 27 27 27 —

Test temperature, Tt , °C, for minimum service temperature, Ts, °C Ts – 40

– 40 > Ts – 60

Ts < – 60

–30 –30 –30 –30 – 40 *

– 40 – 40 – 40 – 40 – 60 *

–60 – 60 – 60 – 60 * *

*Welded construction using 480WT and 700QT steels shall require Approval and special considerations. Joining by bolting is recommended for these applications.



Table 10.14B Impact test temperatures and Charpy impact energy requirements for weld metal in primary tension members (See Clauses 10.23.3.5 and 10.23.4.2–10.23.4.5.) Test temperature, Tt , °C, for minimum service temperature, Ts, °C

Base metal CSA G40.21 grade

Minimum average energy, J

Ts – 40

Ts < – 40

260 WT 300 WT 350 WT and AT 400 WT and AT 480 WT and AT 700 QT

20 20 27 27 27 40

–30 –30 –30 –30 – 35 –45

–40 – 40 – 40 – 40 – 45 – 45

10.23.4 Welding of fracture-critical and primary tension members 10.23.4.1 General The requirements of Clauses 10.23.4.2 to 10.23.4.6 and 10.24 shall apply to the welding of fracture-critical and primary tension members. 

10.23.4.2 Welding consumables Except as permitted by Clause 10.23.4.5, only welding consumables with Charpy V-notch toughness requirements in compliance with Tables 10.14A and 10.14B, as applicable, and certified by the Canadian Welding Bureau to CAN/CSA-W48 shall be used. In the absence of an applicable CAN/CSA-W48 requirement, the applicable Standard(s) in the American Welding Society A5 series of Standards shall be used. In groove welds connecting two different grades of steel, the classification of consumables used, including Charpy V-notch impact requirements, shall be that applicable to the grade with the lower ultimate tensile strength.

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10.23.4.3 Approval and verification of consumables



10.23.4.4 Welding 700Q and 700QT steels

For groove welds in fracture-critical and primary tension members using certified consumables where the Charpy V-notch test temperature required by Tables 10.14A and 10.14B is lower than the test temperature required by CAN/CSA-W48 or the applicable Standard(s) in the American Welding Society A5 series of Standards, or where these Standards are not applicable, welding consumables shall be Approved by the Canadian Welding Bureau and qualified using a verification test assembly to establish the impact properties of the weld metal. The test procedures shall be those specified in CAN/CSA-W48 or the applicable American Welding Society Standard, except that only Charpy V-notch tests shall be required and welding shall be carried out using the preheat and the maximum heat input to be used in practice. The Charpy V-notch results shall meet the requirements of Table 10.14A or 10.14B, as applicable. Qualification shall be required for each electrode diameter used and for the consumables supplied by each manufacturer. The qualification shall be valid for consumables for all groove weld procedures that use a heat input the same as or lower than that used in the qualification test.

For groove weld procedures involving fracture-critical and primary tension members made of 700Q and 700QT steels, consumables shall be qualified by welding procedure tests and Approved by the Canadian Welding Bureau. The tests shall be conducted in accordance with CSA W47.1 using 700Q or 700QT steels for the base plate and shall include weld metal and heat-affected zone (HAZ) Charpy V-notch impact tests in accordance with Appendix E of CSA W47.1. Weld metal impact tests shall meet the requirements of Table 10.14A or 10.14B, as applicable, and HAZ impact tests shall meet the requirements of Tables 10.12 or 10.13 for the base plate, as applicable. Only manufacturers of qualified consumables shall supply consumables for fabrication. The qualification shall be valid for all groove weld procedures that use a heat input the same as or lower than that used in the qualification test. 

10.23.4.5 Qualification of consumables When the welding consumables have not previously been certified by the Canadian Welding Bureau, they shall be qualified by welding procedure tests in accordance with Clause 11.8.2.1(b) of CSA W47.1 and shall include Charpy V-notch impact tests of the weld metal. For steels other than 700Q and 700QT Charpy V-notch tests in the HAZ shall not be required. Weld metal Charpy V-notch properties shall be established by qualification tests in accordance with CSA W47.1 (including Appendix E) and shall meet the requirements of Tables 10.14A and 10.14B, as applicable. Only manufacturers of qualified consumables shall supply consumables for fabrication. Qualification testing shall be performed for each lot or batch of consumables. The qualification shall be valid for all weld procedures that use a heat input the same as or lower than that used in the qualification test. Consumables for 700Q and 700QT steels shall be qualified in accordance with Clause 10.23.4.4.

10.23.4.6 Tack welds and temporary welds Tack welds shall not be used on fracture-critical or primary tension members unless they are incorporated into the final weld. Temporary welds shall not be used on fracture-critical or primary tension members, or on flange material in compression, unless Approved.

10.23.5 Welding corrections and repairs to fracture-critical members 10.23.5.1 General Except as specified in Clause 10.23.5.4(c), repairs to base metal and to welded joints shall be documented. The documentation shall include all of the details specified in Clauses 10.23.5.6 and 10.23.5.7. Welding repair procedures shall be Approved by the Engineer in accordance with Clauses 10.23.5.4 and 10.23.5.5, as applicable.

10.23.5.2 Repair of base metal Repair of base metal by welding at the producing mill shall not be permitted.

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10.23.5.3 Approval and tests for repairs Repair welding may be performed using any appropriate welding procedure Approved by the CWB for the fabrication of fracture-critical members and primary tension members. All repair welding shall be subject to non-destructive tests as specified in Clauses 10.23.5.7(n) and 10.23.6.

10.23.5.4 Approval for non-critical repairs The constructor shall prepare written repair procedures for non-critical repairs as specified in this Clause and submit them to the Engineer for prior Approval. These procedures shall apply to shop repair of discontinuities identified during fabrication. Such Approved repair procedures shall be employed after the Engineer or the Engineer’s agent has verified that the discontinuity to be repaired is as described in the Approved procedures. Repairs that may receive prior Approval include the following: (a) Repairs of welds because of rollover, undercut, or insufficient throat that does not require excavation. (b) Repairs of welds requiring excavation of defects (including porosity, slag, and lack of fusion), repair of arc strikes, and removal of tack welds not incorporated into a final weld. (c) Visually detected planar and laminar discontinuities as specified in Table 5.2 of CSA W59, but not deeper than 25 mm or one-half the thickness of the edge of the cut plate, whichever is less. Such discontinuities shall not be within 300 mm of a tension groove weld. There shall also be no visible planar or laminar discontinuity on any prepared face of a tension groove joint prior to welding. (d) Occasional gouges exceeding 5 mm, but not more than 10 mm deep on edges not to be welded, which may be repaired by welding. The procedures specified in Clause 5.3.4 of CSA W59 shall be followed. Gouges not more than 5 mm deep on otherwise satisfactory cut or rolled surfaces that can be repaired by machining or grinding without welding shall not require prior Approval. The procedures specified in Clause 5.3.4 of CSA W59 shall be followed.

10.23.5.5 Approval for critical repairs Repair procedures beyond those described in Clause 10.23.5.4 shall be considered critical and shall be Approved individually before repair welding can begin. Note: Critical repairs include the following: (a) repairs of lamellar tears, laminations, and cracks, except those meeting the requirements of Clause 10.23.5.4(c); (b) repairs of surface or internal defects in rolled products, except those meeting the requirements of Clause 10.23.5.4(c); (c) dimensional corrections requiring weld removal and rewelding; and (d) any correction by welding to compensate for a fabrication error, e.g., improper cutting or punching or incorrect assembly (other than tack-welded or temporary assemblies).

10.23.5.6 Descriptions of deficiencies and repairs Repair procedures in accordance with Clauses 10.23.5.4 and 10.23.5.5 shall include sketches or full-size drawings, as necessary, to adequately describe the deficiencies and the proposed method of repair. Critical repair procedures in accordance with Clause 10.23.5.5 shall include the location of the discontinuity.

10.23.5.7 Minimum steps for repair Repair procedures, except in cases meeting the requirements of Clause 10.23.5.4(a), shall include at least the following steps, which shall be performed in the following order: (a) Surfaces shall be cleaned, ground, or both, as necessary, to aid visual and non-destructive tests to enable the constructor and Engineer to identify and quantify the discontinuities. (b) The discontinuities shall be drawn as they appear from visual inspection and non-destructive testing. (c) Arc-air gouging, when necessary, shall be part of the Approved welding procedure. (d) Magnetic particle inspection, or another inspection method approved by the Engineer, shall be used to determine whether the discontinuities were removed as planned. (e) All air-carbon-arc gouged and oxygen-cut surfaces that form a boundary for a repair weld shall be ground to form a smooth, bright surface. Oxygen gouging shall not be used. (f) All required runoff tabs and backup bars shall be shown in detail. (g) Preheat and interpass temperatures shall be in accordance with Table 10.15. Preheat and interpass temperatures shall be maintained without interruption until the repair is completed. November 2006

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(h) The repair procedures shall refer to the applicable welding procedure specification and the related data sheet. If both of these were Approved by the Canadian Welding Bureau before fabrication, they need not be qualified by test for the specific method of repair unless a change in essential variables has been made or unless otherwise required by the Engineer. (i) If the geometry of the repair joint or of the excavation is similar to the geometry of a prequalified joint preparation as specified in CSA W59 and permits good access to all portions of such joints or excavations during the proposed sequence of welding, it shall not require qualification by test unless required by the Engineer. (j) Peening, when required, shall be completely described and shall be Approved. Peening equipment shall not contaminate the joint. (k) Post-heat shall be employed and shall continue without interruption from the completion of repair welding to the end of the minimum specified post-heat period. Post-heat of the repair area shall be between 200 and 260 °C and shall continue for at least 1 h for each 25 mm of weld thickness, or for 2 h, whichever is less. (l) Faces of repairs shall be ground flush with the plate or blended to the same contour and throat dimension as the remaining sound weld. (m) If stress-relief heat treatment is required, it shall be completely described. Final acceptance non-destructive testing shall be performed after stress relief is complete. (n) Repairs of groove welds in fracture-critical members shall be examined by ultrasonic testing and radiographic testing. Fillet weld repairs shall be examined by magnetic particle testing. Radiographic testing shall comply with Clause 7.4.2 of CSA W59 and may be performed as soon as the weldment has cooled to ambient temperature. Ultrasonic testing and magnetic particle testing shall comply with Clause 7.4.3 and 7.4.4, respectively, of CSA W59. Final acceptance testing by magnetic particle and ultrasonic methods shall not be performed until the steel weldments have been at ambient temperature for at least the elapsed time specified in Table 10.16.

Table 10.15 Preheat and interpass temperature for steel grades (See Clause 10.23.5.7.) CSA G40.21 grade Plate thickness, t, mm

260WT, 300WT, 350WT, 400WT, 480WT, 350AT 400AT, and 480AT

700QT*

t ≤ 25 25 < t ≤ 40 t > 40

65 °C 120 °C 175 °C

65 °C 120 °C 175 °C

*The maximum preheat and interpass temperatures shall not exceed the recommendations of the steel manufacturer.

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Table 10.16 Minimum elapsed time for acceptance testing (See Clause 10.23.5.7.)

Plate thickness, t, mm

Magnetic particle for fillet welds

Ultrasonic examination of groove welds

t  50 t > 50

24 h 24 h

24 h 48 h

10.23.5.8 Compliance with Approved procedures All repair welding and non-destructive testing shall be performed as described in the Approved repair procedure.

10.23.5.9 Records Approved critical repair procedures shall be retained as part of the project records.

10.23.6 Non-destructive testing of fracture-critical members The use of Cobalt 60 as a radiographic source in quality control shall be permitted only when the steel being tested is more than 75 mm thick. The Constructor shall maintain documentation of all visual and non-destructive testing for review and confirmation by the Engineer. The documentation shall be submitted to the Engineer on completion of the project.

10.24 Construction requirements for structural steel 10.24.1 General Clauses 10.24.2 to 10.24.10 specify requirements for the construction of structural steel for highway bridges and applies unless otherwise specified by the authority having jurisdiction. The requirements specified in these Clauses are provided to ensure compliance with the design philosophy of this Section.

10.24.2 Submissions 10.24.2.1 General Erection diagrams, shop details, welding procedures, and erection procedure drawings and calculations shall be submitted to the Owner. This requirement shall be stipulated on the Plans.

10.24.2.2 Erection diagrams Erection diagrams are general-arrangement drawings showing or indicating the principal dimensions of the bridge, piece marks, the sizes of all members, field welding requirements, the sizes and types of bolts, and bolt installation requirements.

10.24.2.3 Shop details Shop details shall provide (a) full detail dimensions and sizes of all component parts of the structure. These dimensions shall make allowance for changes in shape due to weld shrinkage, camber, and any other effects that cause finished dimensions to differ from initial dimensions; (b) all necessary specifications for the materials to be used; (c) identification of areas requiring special surface treatment; (d) identification of fracture-critical and primary tension members and component parts; May 2010 (Replaces p. 519, November 2006)

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(e) bolt installation requirements; and (f) details of all welds.

10.24.2.4 Welding procedures Welding procedures shall comply with CSA W47.1.

10.24.2.5 Erection procedure drawings and calculations The erection procedure drawings and calculations shall fully indicate the proposed method of erection, including the sequence of erection, the weights and lifting points of the members, and the location and lifting capacities of the cranes used to lift them. Details of temporary bracing and bents to be used during construction shall be shown. Calculations shall be provided to show that members and supports are not overloaded during erection.

10.24.2.6 Symbols for welding and non-destructive testing The symbols for welding and non-destructive testing on shop drawings shall be in accordance with CSA W59.

10.24.3 Materials 10.24.3.1 Steel Substitution of steel members or components for size and grade shall not be permitted unless Approved. All steel shall be new. Acceptance of any material by an inspector shall not preclude subsequent rejection of the material if it is found defective. 

10.24.3.2 High-strength bolts, nuts, and washers Nuts and bolts shall be shipped together as an assembly. The nuts of galvanized fasteners shall be overtapped by the minimum amount required for assembly and shall be lubricated with a lubricant containing a visible dye. The use of a mechanically deposited zinc coating shall require Approval.



10.24.3.3 — Deleted



10.24.3.4 — Deleted 10.24.4 Fabrication 10.24.4.1 Quality of work The standards for quality of work and finish shall comply with the best modern practices for steel bridge fabrication (with particular attention to the appearance of parts exposed to view).

10.24.4.2 Storage of materials Plain or fabricated structural steel shall be stored above the ground on skids or other supports and kept free from dirt and other foreign matter. Long members shall be adequately supported to prevent excessive deflection.

10.24.4.3 Plates 10.24.4.3.1 Direction of rolling Unless otherwise shown on the Plans, steel plates for main members (and their splice plates) shall be cut so that the primary direction of rolling is parallel to the direction of tensile or compressive stress.

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10.24.4.3.2 Plate edges Sheared edges of plates more than 16 mm thick and carrying calculated tension shall be planed, milled, or ground a minimum of 3 mm. Oxygen cutting of structural steel shall be done by machine, except that hand-guided cutting shall be allowed for copes, blocks, and similar cuts where machine cutting is impracticable. Re-entrant corners shall be free from notches and shall have a fillet of the largest practical radius, but not less than 25 mm. The quality and repair of the cut edges shall comply with Clause 5 of CSA W59. All cut edges shall have a surface roughness not greater than 1000, as specified by CSA B95. Corners of oxygen-cut girder flange tips shall be chamfered 2.0 mm by grinding.

10.24.4.3.3 Camber in web plates Webs shall be cut to the prescribed camber, with allowance for shrinkage due to cutting and subsequent welding. The requirements of Clauses 10.7.4.2 and 10.7.4.3 shall also apply.

10.24.4.3.4 Bent plates The following requirements shall apply to bent plates: (a) Load-carrying, rolled steel plates to be bent shall (i) be cut from the stock plates so that the bend line is at right angles to the direction of rolling, except as otherwise Approved for orthotropic decks; and (ii) have their corners lightly chamfered by grinding in the region of the bend before bending. (b) Cold bending shall be carried out so that no cracking or tearing of the plate occurs. Minimum bend radii, measured to the concave face of the metal, shall be as shown in Table 10.17. (c) Hot bending at a plate temperature not greater than 600 °C shall be used to form radii less than those specified for cold bending. Accelerated cooling using compressed air or water shall be used for a hot bent component only when its temperature is below 300 °C.

Table 10.17 Minimum bend radii for bent plates (See Clause 10.24.4.3.4.)

t, mm

Minimum radius

12 or less

2t

Over 12 to 25

2.5t

Over 25 to 38

3t

Over 38 to 65

3.5t

Over 65 to 100 4t

10.24.4.4 Straightening material All steel shall be flat and straight before being worked. Steel with sharp kinks or bends may be rejected. Attempts to straighten sharp kinks or bends shall require Approval. Rolled plates, sections, and built-up members may be straightened using mechanical means or by the application of a controlled heating procedure in accordance with Clause 5.10.5 of CSA W59. After straightening of a bend or buckle, the surface of the steel shall be examined for evidence of fracture or other damage and corrective action taken if necessary.

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10.24.4.5 Bolt holes 10.24.4.5.1 General All holes shall be drilled or reamed to the finished diameter, except that punched holes shall be allowed in material up to 16 mm thick. When shown on the Plans, oversize or slotted holes in accordance with Clause 10.18.4.2 are permitted.

10.24.4.5.2 Punched holes The diameter of a punched hole shall be not more than 2 mm larger than the nominal diameter of the bolt unless oversize holes are specified. The diameter of the die shall not exceed the diameter of the punch by more than 2 mm. Holes shall be clean cut and without ragged or torn edges, but the lightly conical hole that results from clean cutting shall be acceptable. Holes may be reamed to admit fasteners.

10.24.4.5.3 Reamed holes Holes that are to be reamed to final diameter shall first be subdrilled or subpunched to 4 mm smaller than the nominal diameter of the bolt. With the connecting parts assembled and securely held, the holes shall then be reamed to 2 mm larger than the nominal diameter of the bolts. The parts shall be match-marked before disassembly.

10.24.4.5.4 Drilled holes Holes that are drilled full-size shall be 2 mm larger than the nominal diameter of the bolt unless oversize holes have been specified. They shall be accurately located by using suitable numerically controlled drilling equipment, or by using a steel template carefully positioned and clamped to the steel. The accuracy of the holes prepared in this manner, and their locations, shall be such that like parts are identical and require no match-marking. The holes for any connection may be drilled full-size when the connecting parts are assembled and clamped in position, in which case the parts shall be match-marked before disassembly.

10.24.4.6 Pins and rollers Pins and rollers shall be accurately turned to the dimensions and finish shown on the drawings and shall be straight and free from flaws. Pins and rollers more than 175 mm in diameter shall be forged and annealed. Pins and rollers 175 mm or less in diameter may be either forged and annealed or of cold-finished carbon-steel shafting. Holes for pins shall be bored to the specified diameter and finish at right angles to the axis of the member. The diameter of the pin hole shall not exceed that of the pin by more than 0.5 mm for pins 125 mm or less in diameter or more than 0.75 mm for larger pins. Pin holes shall be bored on completion of the assembly of built-up members.

10.24.4.7 Curved girders 10.24.4.7.1 General Flanges of curved, welded I-girders may be cut to the radius. However, they may be curved by applying heat if the radius, R, is greater than 45 000 mm and also exceeds

37bf h Fy y w

and

51 700bf Fy y

where Fy

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10.24.4.7.2 Heat curving of rolled beams and welded girders Steel beams and girders with a specified minimum yield point greater than 350 MPa shall not be heat curved. In heat curving using the continuous or V-type heating pattern, the temperature of the steel shall not exceed 600 °C, as measured by temperature-indicating crayons. A detailed procedure for the heat-curving operation shall be submitted for review. The procedure shall describe the type of heating to be employed, the extent of the heating patterns, the sequence of operations, and the method of support of the girder, including an assessment of any dead-load stresses present during the operation. Transverse web stiffeners may be welded in place either before or after the heat-curving operation. However, unless allowance is made for the longitudinal shrinkage, bracing connection plates and bearing stiffeners shall be located and welded after curving. Girders shall be cambered before heat curving. Rolled sections may be heat cambered using an Approved procedure. Plate girders shall have the required camber cut into the web, with suitable allowance for camber loss due to cutting, welding, and heat curving. 

10.24.4.8 Identification marking Each member shall carry an erection mark for identification. Low-stress stamps — stamps with blunt-nosed markings — may be used on low-stress areas of main members or on secondary members as a means of permanent identification.

10.24.5 Welded construction 

10.24.5.1 General All welding procedures, including those related to quality of work, techniques, repairs, and qualifications, shall comply with CSA W47.1 and CSA W59, except where modified by Clauses 10.24.5.2 to 10.24.5.7.

10.24.5.2 Processes with limited application The electroslag and electrogas welding processes specified in Clause 5 of CSA W59 shall not be used for welding quenched and tempered steels or for welding components of members subject to tension stress or stress reversal.

10.24.5.3 Primary tension and fracture-critical members Members and components of members designated primary-tension or fracture-critical shall meet the requirements of Clause 10.23 in addition to the requirements of CSA W59. The use of heat to alter the sweep or camber of fracture-critical girders shall require Approval. 

10.24.5.4 Submissions CWB-accepted welding procedure specifications, data sheets, and repair procedures for prequalification shall be submitted to the Owner in compliance with the Plans.



10.24.5.5 Certification of welding operations Any company undertaking welded fabrication and/or welded erection (including steel piles, railings and guards, or other welded attachments) shall be certified to Division 1 or 2 of CSA W47.1.



10.24.5.6 Complete joint penetration groove welds Complete joint penetration groove welds shall conform to CSA W59, Clause 12. Runoff tabs or extension bars shall be provided so that groove welds terminate on the tab and shall be removed upon completion of the joint. The welds that attach the tabs to the piece being welded shall be placed inside the joint so that they are incorporated into the final weld. The conditions for the type, use, and removal of the welding backing bar, if used, shall comply with CSA W59, Clause 12, or as otherwise directed by the Engineer.

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10.24.5.7 Web to flange fillet welds Where practicable, web to flange fillet welds shall be made continuously by machine or automatic welding. Welds may be repaired using either a semi-automatic or manual process, but the repaired weld shall blend smoothly with the adjacent welds.

10.24.6 Bolted construction 10.24.6.1 General Clauses 10.24.6.2 to 10.24.6.11 specify requirements for bolted steel construction using ASTM A 325/A 325M or ASTM A 490/A 490M high-strength bolts.

10.24.6.2 Assembly When assembled, all joint surfaces, including those adjacent to bolt heads, nuts, and washers, shall be free from loose scale, burrs, dirt, and foreign material that would prevent the solid seating of the parts. The faying surfaces of connections designed in accordance with Clause 10.18.2.3.2 shall be prepared as follows: (a) For clean mill scale, the surfaces shall be free from oil, paint, lacquer, or any other coating in all areas within the bolt pattern and for a distance beyond the edge of the bolt hole that is the greater of 25 mm or the bolt diameter. (b) For Classes A and B (see Table 10.9), the surfaces shall have the same blast cleaning and coating application as was used in the tests to determine the mean slip coefficient. Coated joints shall not be assembled before the coating has cured for the minimum time used in the tests to determine the mean slip coefficient. (c) For Class C (see Table 10.9), the surfaces shall be hot-dip galvanized in accordance with CAN/CSA-G164 and subsequently roughened by hand wire-brushing. Power wire-brushing shall not be used.

10.24.6.3 Installation of bolts Pretensioned bolts shall be tightened in accordance with Clause 10.24.6.6 to at least 70% of the minimum tensile strength specified in the applicable ASTM Standard.

10.24.6.4 Hardened washers The following requirements shall apply to hardened washers: (a) Hardened washers shall be provided as follows under the element turned (head or nut) during installation: (i) as required by Clause 10.24.6.7; and (ii) for ASTM A 490/A 490M bolts. (b) Hardened washers shall also be required (i) for oversize or slotted holes that meet the requirements of Clause 10.18.4.2; (ii) under the head and nut of ASTM A 490/A 490M bolts when used with steel with a specified minimum yield strength of less than 280 MPa; and (iii) when ASTM A 490/A 490M bolts of greater than 26 mm diameter are used in oversize or slotted holes. The washers in this case shall have a minimum thickness of 8 mm.

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10.24.6.5 Bevelled washers Bevelled washers shall be used to compensate for lack of parallelism where, in the case of ASTM A 325/A 325M bolts, an outer face of bolted parts has more than a 5% slope with respect to a plane normal to the bolt axis. In the case of ASTM A 490/A 490M bolts, bevelled washers shall be used to compensate for any lack of parallelism due to the slope of outer faces.

10.24.6.6 Turn-of-nut tightening After the holes in a joint are aligned, a sufficient number of bolts shall be placed and brought to a snug-tight condition to ensure that the parts of the joint are brought into full contact with each other. Following the initial snugging operation, bolts shall be placed in any remaining open holes and brought to snug-tightness. Resnugging can be necessary in large joints. When all bolts are snug-tight, each bolt in the joint shall be further tightened by the applicable amount of relative rotation specified in Table 10.18, with tightening progressing systematically from the most rigid part of the joint to its free edges. During this operation, there shall be no rotation of the part not turned by the wrench unless the bolt and nut are match-marked to enable the amount of relative rotation to be determined. 

Table 10.18 Nut rotation from snug-tight condition* (See Clauses 10.24.6.6 and 10.24.6.7.) Disposition of outer faces of bolted parts

Bolt length†

Turn from snug

Both faces normal to the bolt axis or one face Up to and including four diameters normal to the axis and the other sloped 1:20  Over four diameters and not (bevelled washers not used)‡ exceeding eight diameters or 200 mm

1/3

Exceeding eight diameters or 200 mm

2/3

All lengths

3/4

Both faces sloped 1:20 from normal to the bolt axis (bevelled washers not used)‡

1/2

*Nut rotation is rotation relative to a bolt regardless of whether the nut or bolt is turned. The tolerance on rotation is 30° over. This Table applies to coarse-thread, heavy-hex structural bolts of all sizes and lengths used with heavy-hex semi-finished nuts. †Bolt length is measured from the underside of the head to the extreme end point. ‡Bevelled washers are necessary when ASTM A 490/A 490M bolts are used.

10.24.6.7 Inspection An inspector shall determine whether the requirements of Clauses 10.24.3.2 and 10.24.6.2 to 10.24.6.6 have been met. Installation of bolts shall be observed to ascertain that a proper tightening procedure is employed. The turned element of all bolts shall be visually examined for evidence that they have been tightened. When properly installed, the tip of the bolt shall be flush with or outside the face of the nut. Tensions in bolts installed by the turn-of-nut method exceeding those specified in Clause 10.24.6.3 shall not be cause for rejection. When there is disagreement concerning the results of an inspection of bolt tension, the following arbitration procedure shall be used unless a different procedure has been specified: (a) The inspector shall use an inspection wrench that is a manual or power torque wrench capable of indicating a selected torque value. (b) Three bolts of the same grade and diameter as those under inspection and representative of the lengths and conditions of those in the bridge shall be placed individually in a calibration device capable of measuring bolt tension. There shall be a washer under the part turned if washers are so used in the bridge or, if no washer is used, the material abutting the part turned shall be of the same specification as that in the bridge. May 2010 (Replaces p. 525, November 2006)

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(c) When the inspection wrench is a manual wrench, each bolt specified in Item (b) shall be tightened in the calibration device by any convenient means to an initial tension of approximately 15% of the required fastener tension, and then to the minimum tension specified for its size in Clause 10.24.6.3. Tightening beyond the initial condition shall not produce greater nut rotation beyond that permitted by Table 10.18. The inspection wrench shall then be applied to the tightened bolt and the average torque necessary to turn the nut or head 5° in the tightening direction shall be determined. The average torque measured in these tests of three bolts shall be taken as the job inspection torque to be used in the manner specified in Item (e). The job inspection torque shall be established at least once each working day. (d) When the inspection wrench is a power wrench, it shall first be applied to produce an initial tension of approximately 15% of the required fastener tension and then adjusted so that it will tighten each bolt specified in Item (b) to a tension of at least 5% but not more than 10% greater than the minimum bolt tension specified for its size in Clause 10.24.6.3. This setting of the wrench shall be taken as the job inspection torque to be used in the manner specified in Item (e). Tightening beyond the initial condition shall not produce greater nut rotation than that permitted by Table 10.18. The job inspection torque shall be established at least once each working day. (e) Bolts represented by the sample specified in Item (b) that have been tightened in the bridge shall be inspected by applying, in the tightening direction, the inspection wrench and its job inspection torque to 10% of the bolts (but not fewer than two bolts) selected at random in each connection. If no nut or bolt head is turned by this application of the job inspection torque, the connection shall be accepted as being properly tightened. If any nut or bolt head is turned by the application of the job inspection torque, this torque shall be applied to all of the bolts in the connection, and all of the bolts whose nut or head is turned by the job inspection torque shall be retightened and reinspected. Alternatively, the fabricator or erector, at his or her option, may retighten all of the bolts in the connection and then resubmit the connection for inspection.

10.24.6.8 Reuse of bolts ASTM A 490/A 490M and galvanized ASTM A 325/A 325M bolts shall not be reused once they have been fully tightened. Other ASTM A 325/A 325M bolts may be reused up to two times, provided that proper control on the number of reuses can be established. Touch-up of pretensioned bolts in a multi-bolt joint shall not constitute a reuse unless a bolt becomes substantially unloaded as other parts of the joint are bolted.

10.24.6.9 Shop trial assembly Girders and other main components shall be preassembled in the shop in order to prepare or verify the field-splices. Components shall be supported in a manner consistent with the finished geometry of the bridge, as specified on the Plans, with allowance for any camber required to offset the effects of dead load deflection. Holes in the webs and flanges of main components shall be reamed or drilled to final size while in assembly. The components shall be pinned and firmly drawn together by bolts before reaming or drilling. Drifting done during assembly shall be sufficient only to align the holes and not to distort the steel. If necessary, reaming shall be used to enlarge holes. When a number of sequential assemblies are necessary because of the length of the bridge, the second and subsequent assemblies shall include at least one section from the preceding assembly to provide continuity of alignment. Trial assemblies shall be required whether the field-splices are bolted or welded. Each assembly shall be checked for camber, alignment, accuracy of holes, and fit-up of welded joints and milled surfaces. Corrective work, if necessary, shall be carried out at no cost to the Owner.

10.24.6.10 Holes drilled using numerically controlled machines As an alternative to the trial assembly specified in Clause 10.24.6.9 when the bolt holes have been prepared by numerically controlled drilling or using a suitable template, the accuracy of the drilling may be demonstrated by a check assembly consisting of the first components of each type to be made. If the check assembly is satisfactory, further assemblies of like components shall not be required.

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If the check assembly is unsatisfactory for any reason, the work shall be redone or repaired in a manner acceptable to the Owner. Further check assemblies shall be required, as specified by the Owner, to demonstrate that the required accuracy of fit-up has been achieved.

10.24.6.11 Match-marking Connecting parts that are assembled in the shop for reaming or drilling holes shall be match-marked. A drawing shall be prepared to show how the marked pieces should be assembled in the field to replicate the shop assembly.

10.24.7 Tolerances 10.24.7.1 Structural members Structural members consisting of a single rolled shape shall meet the straightness tolerances of CSA G40.20, except that columns shall not deviate from straight by more than 1/1000 of the length between points of lateral support. A variation of 1 mm from the detailed length shall be permissible in the length of members that have both ends finished for contact bearing. Other members without finished ends may have a variation from the detailed length of not more than 2 mm for members 10 m or less in length, and not more than 4 mm for members over 10 m in length. 

10.24.7.2 Abutting joints When compression members are butted together to transmit loads in bearing, the contact faces shall be milled or saw-cut. The completed joint shall have at least 75% of the entire contact area in full bearing, defined as not more than 0.5 mm separation, and the separation of the remainder shall not exceed 1 mm. At joints where loads are not transferred in bearing, the nominal dimension of the gap between main members shall not exceed 10 mm, with a tolerance of ±5 mm from the nominal dimension.

10.24.7.3 Facing of bearing surfaces The surface finish of bearing surfaces that are in contact with each other or with concrete shall meet the roughness requirements specified in CSA B95 and Table 10.19. Surfaces of flanges that are in contact with bearing sole plates shall be flat within 0.5 mm over an area equal to the projected area of the bearing stiffeners and web. Outside this area, a 2 mm deviation from flat shall be acceptable. The bearing surface shall be perpendicular to the web and bearing stiffeners.

Table 10.19 Facing of bearing surfaces roughness requirements (See Clause 10.24.7.3.) Surface roughness Contact surfaces

Micro-inches

Microns

Steel slabs or plates in contact with concrete Plates in contact as part of bearing assemblies Milled ends of compression members Milled or ground ends of stiffeners Bridge rollers or rockers Pins and pin holes Sliding bearings — Steel/copper alloy  or steel/stainless steel

2000 1000 500 500 250 125 125

50 25 13 13 6 3 3

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10.24.7.4 Bearing plates Bearing plates shall meet the following requirements: (a) rolled steel bearing plates 50 mm or less in thickness may be used without planing if a satisfactory contact bearing is obtained; (b) rolled steel bearing plates more than 50 mm thick but not more than 100 mm thick may be straightened by pressing or by planing on all bearing surfaces to obtain a satisfactory contact bearing; and (c) rolled steel bearing plates more than 100 mm thick shall be planed on all bearing surfaces, except for those surfaces that are in contact with concrete foundations and are grouted to ensure full bearing.

10.24.7.5 Fabricated components The tolerances for welded components shall comply with Clause 5.4 of CSA W59. The dimensional tolerances of welded structural members shall be those specified in Clauses 5.8 and 12.5.3 of CSA W59. Built-up, bolted structural members shall comply with the straightness tolerances specified in CSA G40.20 for rolled wide-flanged shapes. Bearing stiffeners fitted to bear shall have a minimum bearing contact area of 75% and a maximum separation of 1 mm over the remaining area. Fitted intermediate stiffeners shall have a minimum bearing contact area of 25% and a maximum separation of 2 mm.

10.24.8 Quality control 10.24.8.1 Qualification of inspectors Welding inspectors shall be qualified by the CWB to the requirements of CSA W178.2. 

10.24.8.2 Non-destructive testing of welds At least the following non-destructive testing of welds shall be performed: (a) visual inspection of all welds; (b) radiographic or ultrasonic inspection of groove welds in flanges and webs of built-up girders, as follows: (i) flange splices in tension or stress reversal zones: 100%; (ii) flange splices in compression zones: 25%; and (iii) web splices: 100% for one-half of the depth from the tension flange and 25% for the remainder of the web; (c) magnetic particle inspection of web-to-flange fillet welds, as follows: (i) submerged-arc welds: 25%; (ii) semi-automatic welds: 50%; and (iii) manual welds: 100%; and (d) magnetic particle inspection of fillet welds, as follows, for connection plates and stiffeners to which cross-bracing or diaphragms are attached: (i) for one-half of the depth from the tension flange: 100%; and (ii) transverse welds on tension flanges: 100%. Radiographic and ultrasonic testing shall be performed before assembly of the flanges to the webs.

10.24.8.3 Acceptance standards for weld defects The acceptance standards for dynamically loaded structures specified in Clause 12.5.4 of CSA W59 shall apply to weld defects.

10.24.8.4 Repair of welds Welds that do not meet the acceptance standards specified in Clause 10.24.8.3 shall be removed, rewelded, and retested. Repairs and non-destructive testing of fracture-critical and primary-tension members shall be performed in accordance with Clause 10.23.

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10.24.8.5 Identification of structural steel In the fabricator’s plant, the specification and grade of steel used for main components shall be identified by use of suitable markings or recognized colour coding. Cut pieces that are identified by piece mark and contract number need not continue to carry specification identification markings when it has been established that such pieces conform to the required material specifications. Records shall be kept to identify the heat number of the material and the corresponding mill test report for each component of a fracture-critical or primary tension member. 

10.24.9 Transportation and delivery Structural steel shall be loaded for shipping, transported, unloaded, and stored clear of the ground at its destination without being excessively stressed, deformed, or otherwise damaged. Where possible, plate girders shall be transported with their webs in the vertical plane. Where girders cannot be shipped with their webs in the vertical plane, static and dynamic forces during handling, transport, and storage shall be determined using a dynamic load allowance of at least 100%, unless a lower value can be justified. Computed stresses shall satisfy the provisions of Clause 10.10. Fatigue stresses due to dynamic flexure during transport shall also be considered.

10.24.10 Erection 10.24.10.1 Erection conditions Components shall be lifted and placed using appropriate lifting equipment, temporary bracing, guys, or stiffening devices so that they are not overloaded or unstable. Additional permanent material may be provided, if Approved, to ensure that the member capacities are not exceeded during erection.

10.24.10.2 Falsework All falsework, including necessary foundations, required for the safe construction of a bridge shall be designed, furnished, maintained, and removed by the contractor. The contractor shall not use any of the material intended for use in the finished bridge for temporary purposes during erection, unless such use is Approved.

10.24.10.3 Removal of temporary bracing or guys Temporary bracing or guys shall be removed when nolonger required for the stability of the bridge, unless otherwise Approved.

10.24.10.4 Maintaining alignment and camber The bridge shall be erected to the proper alignment on plan and in elevation, taking into account the specified dead load camber.

10.24.10.5 Field assembly Parts shall be assembled following the piece marks shown on the erection drawings and match-marks. Main girder splices and field connections shall have half their holes filled with fitting-up bolts and drift-pins (half bolts and half pins) before the installing and tightening of the balance of the connection bolts. The fitting-up bolts may be the same high-strength bolts used in the installation. The pins shall be 1 mm larger in diameter than the bolts. Excessive drifting that distorts the metal and enlarges the holes shall not be allowed, although reaming up to 2 mm over the nominal hole diameter shall be permitted, except for oversize or slotted holes.

10.24.10.6 Cantilever erection When cantilever erection is used, splices that support the cantilevering member shall be fully bolted before the cantilever is further extended or loaded.

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10.24.10.7 Repairs to erected material With the exception of splices of main material, the correction of minor misfits involving minor amounts of reaming, cutting, and shimming shall be permitted. The correction of other shop fabrication, or any deformation resulting from handling or transportation that prevents the proper assembly and fitting of the parts, shall require Approval.

10.24.10.8 Field welding Any company undertaking field welding in accordance with this Section shall be certified to Division 1 or 2 of CSA W47.1.

10.24.10.9 Attachments Tack welds intended to be used for attachments or for any other purpose shall not be used unless they subsequently become a part of the welds shown on the Plans. Tack welds that are not part of the welds shown on the Plans shall not be used on any portion of the girders.

10.24.10.10 Protection of the substructure against staining The substructure shall be protected against rust staining by water runoff from the bridge, as specified on the Plans.

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Section 11 — Joints and bearings 11.1 11.2 11.3 11.3.1 11.3.2 11.4 11.4.1 11.4.2 11.5 11.5.1 11.5.2 11.5.3 11.5.4 11.5.5 11.5.6 11.5.7 11.5.8 11.5.9 11.6 11.6.1 11.6.2 11.6.3 11.6.4 11.6.5 11.6.6 11.6.7 11.6.8 11.6.9 11.6.10

Scope 532 Definitions 532 Abbreviations and symbols 533 Abbreviations 533 Symbols 534 Common requirements 534 General 534 Design requirements 535 Deck joints 535 General requirements 535 Selection 536 Design 537 Fabrication 537 Installation 538 Joint seals 538 Sealed joint drainage 538 Open joint drainage 538 Volume control joint 538 Bridge bearings 538 General 538 Metal back, roller, and spherical bearings 539 Sliding surfaces 540 Spherical bearings 543 Pot bearings 544 Elastomeric bearings 545 Disc bearings 548 Guides for lateral restraints 549 Other bearing systems 550 Load plates and attachment for bearings 550

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Section 11 Joints and bearings 11.1 Scope This Section specifies minimum requirements for the design, selection, and detailing of joints and bearings.

11.2 Definitions The following definitions apply in this Section: Armour — an edging to the deck joint comprising a steel angle or a steel plate permanently attached to the concrete dam corners. Bearing — a structural device that transmits loads while allowing translation, rotation, or both. Bridging plate — a structurally integral cantilever plate, e.g., a finger plate, that is rigidly fastened to one side of a joint and permits free movement of the joint. Concrete dam — the area adjacent to the joint that anchors the joint assembly or mechanism. It also provides protection against dynamic impact effects resulting from direct wheel traffic loading. Cover plate — a plate that is not necessarily structurally integral with the joint but covers the joint to provide a safe riding surface. Deck joint or expansion joint — a structural discontinuity between two elements, at least one of which is a deck element, that is designed to permit relative translation or rotation, or both, of abutting structural elements. Disc bearing — a bearing consisting of a restrained single moulded disc of unreinforced elastomer confined by upper and lower metal-bearing plates and prevented from moving horizontally by a shear-restricting mechanism. Effective elastomer thickness — the sum of the thicknesses of all of the elastomeric layers in a bearing, excluding the outer layers. Elastomer — a compound containing (a) virgin natural polyisoprene (natural rubber) (when used in pot bearings and plain or laminated elastomeric bearings); (b) virgin polychloroprene (neoprene) (when used in plain or laminated elastomeric bearings); or (c) polyether-urethane polymer (when used in disc bearings). Elastomeric concrete — a viscous mixture of elastomer, chemical additives, and aggregates that, after being placed as an end expansion-joint dam and cured, retains the joint assembly while providing a resilient transition in the riding surface. Fixed bearing — a bearing that prevents differential translation while permitting rotation of abutting structural elements. Integral abutment bridge — a bridge whose superstructure and abutments are connected monolithically.

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Joint anchorage — each side of the deck joint assembly anchored permanently to the structure in order to transfer all static and dynamic loads from the joint assembly to the structure. Joint seal — a poured or preformed elastomeric component designed to prevent moisture and debris from penetrating joints. Laminated bearing — a bearing made from alternate laminates of elastomer and reinforcing material, fully bonded together during vulcanization. Longitudinal joint — a joint provided to separate a deck into two independent longitudinal structural systems. Metal rocker — a bearing that carries vertical load by direct contact between two metal surfaces and accommodates movement by rolling of one surface with respect to the other. Modular joint — a prefabricated deck joint consisting of multiple joint openings filled with seals. Open joint — a structural discontinuity that permits the passage of water and debris. Plain elastomeric pad — a pad made only of elastomer. Pot bearing — a bearing consisting of a metal piston supported by a single moulded disc of unreinforced elastomer confined within a hollow metal cylinder. Sealed joint — a structural discontinuity that does not permit the passage of water and debris through the joint. Shape factor — the ratio of the area of the loaded face of a bearing and the area of an elastomeric layer around the perimeter of the bearing that is free to bulge. Sliding bearing — a bearing that accommodates differential translation. Spherical bearing — a bearing comprising two spherical metal surfaces in contact with and sliding on matching curved surfaces. Translation — horizontal movement of a bridge in the longitudinal or transverse direction. Volume control joint — a joint assembly that comprises an elastoplastic material that seals and controls the deck joint opening by its ability to vary its shape at constant volume. Zero movement point — a stationary point to which movements resulting from volumetric changes in the structure are related.

11.3 Abbreviations and symbols 11.3.1 Abbreviations The following abbreviations apply in this Section: FLS

— fatigue limit state

PTFE — polytetra fluoroethylene polymer SLS

— serviceability limit state

ULS — ultimate limit state

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11.3.2 Symbols The following symbols apply in this Section: D

= diameter of the loaded contact surface of a spherical bearing projected on the horizontal plane, mm

Dd

= diameter of elastomeric element in a disc bearing, mm

Dp

= internal diameter of pot in a pot bearing, mm

D1

= diameter of the curved surface of a rocker or roller unit, mm

D2

= diameter of the curved surface of a mating unit, mm

Es

= modulus of elasticity of steel, MPa

e

= induced eccentricity of the loading on a bearing, mm

Fy

= yield strength of steel, MPa

Hu

= horizontal load on a bearing or restraint at ULS, N

he

= total effective elastomer thickness, mm

L

= smaller dimension of a rectangular bearing in plan, mm; length of contact of a cylindrical surface, mm

Ps

= total load at SLS, N

Pud

= minimum dead load at ULS, N

pu

= average pressure on the elastomer in a pot bearing at ULS, MPa

R

= radius of a curved bearing contact surface, mm; radius of a circular bearing, mm

S

= shape factor of the thickest layer of elastomer or of the thickness of a plain bearing pad

tw

= thickness of the pot wall in a pot bearing, mm

w

= height of the piston rim in a pot bearing, mm

β θu μ φ

= effective friction angle, degrees = relative rotation of the top and bottom surfaces of a bearing at ULS, degrees = coefficient of friction = resistance factor

11.4 Common requirements 11.4.1 General Deck joints and bearings shall be designed to resist loads and accommodate movements at SLS and ULS. The movements and loads shall be in accordance with the requirements of Section 3. The selection and layout of the joints and bearings shall be consistent with the designed articulation of the structure. The articulation shall accommodate all anticipated deformations induced by loads, restraints, and volumetric changes. No damage due to joint or bearing movement shall be permitted at SLS and no irreparable damage shall occur at ULS. Joint or bearing movements and loads assumed in the design shall be clearly identified on the Plans. All exposed steel components of joints and bearings shall be protected against corrosion. The details and specifications of the corrosion protection system shall be Approved. In the designing and detailing of deck joints and bearings, the following shall be considered: (a) the properties of the materials in the structure, including the coefficient of thermal expansion, the modulus of elasticity, Poisson’s ratio, elastic shortening, creep, and shrinkage; (b) the effective temperature range of the structure; (c) the sizes of the structural members in contact with the bearings; (d) the method and sequence of construction; (e) the anticipated tilt, settlement, and movement of supports;

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(f) the construction tolerances; (g) the static and dynamic response of the structure; (h) the interaction of the force effects to which the structure could be subjected, including those due to dead and live loads, wind, earthquake, and earth pressures; (i) the structural restraints; and (j) inspection and maintenance requirements. In all cases, both short-term and long-term effects shall be considered.

11.4.2 Design requirements Thermal movements calculated from the extreme temperatures specified in Section 3 and the estimated setting temperature shall be accounted for in the design of the joints and bearings. The setting of deck joints and bearings shall be based on the effective bridge temperature at the time of installation, which may be assumed to be the mean shade air temperature taken over the previous 48 h for concrete structures and the previous 24 h for steel structures. The resistance factor, φ, applied to the capacity of a joint or a bearing assembly shall be in accordance with the applicable Section of this Code.

11.5 Deck joints 11.5.1 General requirements 11.5.1.1 Functional requirements Deck joints shall be designed and detailed to accommodate the translation and rotation of the structure at the joint. Deck joints shall be designed to provide for the unhindered passage of traffic across the joints without impairing the riding characteristics of the roadway or damaging vehicles. The type of joint and size of surface gap shall accommodate the safe passage of motorcycles, bicycles, and pedestrians, as necessary. In particular, where bicycle paths and pedestrian walkways are designed as part of the roadway, the gap opening shall be controlled by cover plates or bridging plates so that the maximum opening does not exceed 25 mm. Joint armour, armour connections, and anchors shall be detailed to avoid damage from snowplows. Sealing elements shall be located at least 10 mm below the riding surface. The deck joint components in the vertical faces of curbs, parapet walls, or barrier walls exposed to the action of snowplows or other maintenance equipment shall be recessed at least 20 mm. Where cover plates are used over the sidewalk and curb areas, they shall be installed with the free end pointing in the direction of the adjacent traffic. Protection against snowplow action shall be considered for cover plate installations in driving lanes over roadway areas. Deck joints shall be detailed to prevent damage to components of the structure (e.g., the deck, bearings, piers, and abutments) from water, de-icing chemicals, and roadway debris. Longitudinal deck joints shall be provided, but only where necessary, to accommodate the effects of differential movements between adjacent longitudinal segments of the bridge. Sealed joints shall remain watertight at SLS.

11.5.1.2 Design loads A joint shall be designed to withstand combinations of wheel and horizontal loads with appropriate load factors and dynamic load allowance. A single wheel load, in accordance with the requirements of Section 3, shall be used to calculate the maximum force effects in the various components of the joint. Any portion of the wheel load over the joint gap shall be applied at only one edge of the gap. Load dispersion at an angle not exceeding 45° shall be permitted within the joint components where justified by the continuity and rigidity of the joint. A horizontal load of 60 kN per metre length of the joint shall be applied at the roadway surface, in combination with forces that result from movement of the joint, to produce maximum force effects. November 2006

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11.5.1.3 Structural requirements Deck joints shall satisfy the requirements of SLS, FLS, and ULS. The joints and their supports shall be designed to withstand factored load effects over the range of movements, as specified in Section 3. A joint shall be detailed in such a way that any damage to the joint occurring at ULS is repairable while the bridge remains in service. In calculating the movement at a joint in a bridge superstructure, the length taken as affecting the movement shall be the distance between the reference point and the zero movement point. For curved superstructures, this length shall be taken along the chord. In calculating the location of the zero movement point, the stiffnesses of the supporting systems of the bridge shall be taken into account. All joints, including those in curbs, parapets, and barrier walls, shall be positioned and oriented to accommodate total movement with reference to the zero movement point. The moving components of the joint shall be designed to work in concert with the bearings to avoid binding of the joints and the resulting adverse force effects on the bearings and structural elements.

11.5.1.4 Materials The surface of the joint exposed to pedestrian traffic shall be skid resistant. All materials in the joint shall be durable and resistant to abrasion, corrosion, and damage from traffic and snowplows. Materials directly in contact with each other shall be electrically, thermally, and chemically compatible; where incompatibility exists, materials should be insulated from each other. All fasteners for joints exposed to de-icing chemicals shall be fully protected against corrosion.

11.5.1.5 Maintenance Deck joints shall be designed to operate with a minimum of maintenance. They shall be replaceable (except for elements permanently attached to the structure) and accessible for inspection and maintenance. Sufficient space for access to the joints from below the deck shall be provided by proper detailing of adjacent components. For the deck joints of large bridges not directly accessible from the ground, access, e.g., inspection hatches, ladders, platforms, and catwalks, shall be provided where practicable. Joint armour, armour connections, and anchors shall be detailed to avoid damage from snowplows. The top surface of piers and abutments under deck joints shall be sloped to prevent the accumulation of water and debris.

11.5.2 Selection 11.5.2.1 Number of joints The number of deck joints in a structure shall be kept to a minimum. Preference shall be given to continuous floor systems and superstructures. To permit expansion when required, a joint shall be provided on the approach slabs of integral abutment bridges. The deck and supporting structural system shall be designed to minimize and withstand the forces generated by restraint to movements, unless deck joints and bearings are provided to facilitate the movements.

11.5.2.2 Placement The longitudinal movement of deck joint elements shall be consistent with that provided by the bearings at that location.

11.5.2.3 Types of deck joints A sealed deck joint shall be provided where the joint is located directly above structural members and bearings that would be adversely affected by water and debris accumulation, and where de-icing chemicals are used. It shall seal the surface of the deck, including curbs, sidewalks, medians, and, where necessary, parapet or barrier walls. The joint shall prevent the accumulation of water and debris that could restrict its operation.

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An open deck joint shall be used only if drainage away from the bearings can be ensured year round. Where de-icing chemicals are used, the drainage system shall be adequately protected against corrosion.

11.5.3 Design 11.5.3.1 Bridge deck movements 11.5.3.1.1 Sealed deck joint The width of a roadway surface gap in a transverse deck joint, measured normal to the joint at SLS movement, shall not exceed 100 mm for a joint with a single opening and 80 mm for any gap in a joint with multiple openings. Gaps in a deck joint with multiple openings shall remain equal and parallel to each other. When the skew angle of the deck joint exceeds 20°, only those deck joints whose movement capacity has been demonstrated by the manufacturer shall be permitted.

11.5.3.1.2 Open deck joint The width of the roadway surface gap in an open transverse deck joint shall be not less than 25 mm or greater than 60 mm at SLS movements. Openings exceeding 60 mm shall be used only if Approved.

11.5.3.2 Components 11.5.3.2.1 Bridging plates Joint bridging plates shall be designed as cantilevers capable of supporting wheel loads and accommodating bridge articulation. The possible differential settlement between the two sides of a joint bridging plate should be accommodated in the design and detailing of the bridging plates.

11.5.3.2.2 Armour The armour shall be detailed to eliminate the formation of air voids during placing of adjacent concrete. The armour shall be provided with studs with a minimum diameter of 20 mm or snowplow plates with a minimum thickness of 10 mm. The length of the studs or plates shall be not less than 200 mm. The spacing shall be not more than 200 mm for studs and not more than 300 mm for plates.

11.5.3.2.3 Joint anchorage The joint anchorage shall be connected directly to the structural steel supports or engaged with the reinforced concrete or the elastomeric concrete substrate through bonding. Joint anchorage within elastomeric concrete shall require Approval. Joint anchorage on each side of the deck joint assembly shall satisfy the following minimum requirements: (a) the factored resistance of the joint anchorage shall not be less than 600 kN/m in any direction; (b) the spacing of the armour anchors shall not exceed 250 mm; and (c) where the deck joint assembly is attached by reinforcing bars, studs, or bolts cast into concrete, the total cross-sectional area of the steel anchors shall be not less than 1600 mm2/m.

11.5.3.2.4 Bolts All anchor bolts for bridging plates, joint seals, and joint anchors shall be high-strength bolts fully torqued in accordance with the applicable ASTM Standard. Cast-in-place anchors shall be used only in new concrete. Expansion anchors and countersunk anchor bolts shall not be permitted on any joint connection.

11.5.4 Fabrication Deck joint components shall be of sufficient thickness to stiffen the assembly and prevent distortion due to welding and galvanizing. November 2006

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To ensure proper fit and function, joint components shall be fully assembled in the shop. If possible, the joint and seal shall be shipped to the job site fully assembled; otherwise, permanent seals shall not be placed before joint armouring and anchorage installation have been completed.

11.5.5 Installation The Plans shall include, in tabular form, the installation gap openings throughout the designated installation temperature range. Construction joints and blockouts shall be used where practicable to permit the placement and adjustment of the joint after the backfill and major components have been placed. Where staged construction is used, joint design shall include details for transverse field splices. Splices shall be designed to provide satisfactory fatigue life. Where practicable, splices should be located away from the wheel paths and the gutter areas. Seals shall be installed in one continuous piece.

11.5.6 Joint seals All seals for joints shall accommodate required movements at SLS and ULS and be designed to remain watertight and prevent the accumulation of water and debris that could restrict the operation of the joints. Elastomeric glands or membranes shall be placed in such a way that they remain below the roadway surface at the minimum gap opening in accordance with Clause 11.5.1.1.

11.5.7 Sealed joint drainage Where practicable, drainage accumulated in the sealed joint shall not be discharged on any portion of the structure.

11.5.8 Open joint drainage In the design of open joints, the discharge of water and debris shall be diverted from the bearing areas and structural elements by a suitable system, e.g., a trough-collector-downspout system. Troughs shall have a minimum of 10% slope to facilitate drainage.

11.5.9 Volume control joint A volume control joint shall be designed to transfer all static and dynamic wheel loads to the structure. A volume control joint shall be used only when the maximum joint gap below the seal is less than 20 mm. The width of the joint binder shall be at least ten times the maximum gap of the joint below the seal. The sealant shall have sufficient bond strength with all surfaces with which it is in contact. The use of proprietary volume control joints shall require Approval.

11.6 Bridge bearings 11.6.1 General 11.6.1.1 Bearings shall support and transfer all loads while accommodating translations and rotations in the structure. Uplift-restraint devices shall not restrict the function of a bearing. The bearing seats of the structure shall be detailed to ensure complete contact with the bearing under all load combinations. The following maximum and minimum loads and movements corresponding to the critical combinations at SLS and ULS shall be shown on the Plans: (a) dead load; (b) total load;

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(c) lateral loads; (d) rotations; and (e) translations. Any other requirements that need to be satisfied shall be shown on the Plans. For bearings other than elastomeric bearings, the design-bearing rotation, θu , shall be taken as the sum of the rotations due to ULS loads and tolerances in fabrication and installation, plus 1°. Bearings shall be designed to operate with minimal maintenance. They shall be accessible for inspection and maintenance and replaceable without damage to the structure or removal of anchorages permanently attached to the structure. To facilitate their placement, bearings shall be detailed so that they can be removed by jacking the superstructure by an amount not exceeding the vertical relaxation recovery of the elastomeric material within the bearing plus 5 mm. For bearings with sliding elements, the Plans shall include a table of the required settings throughout the probable temperature range at the time of installation. Bearings shall be plant assembled so that their assembly remains intact during transportation and installation. The temporary connections shall be removed only after the bearings have been installed with permanent connections. The bearings shall be set to the specified plane within a tolerance of ± 0.2° in any direction. The top of a bearing shall be set at the specified elevation within Approved tolerances. Grout bedding for bearings used for surface levelling shall meet the requirements of the Regulatory Authority. The grout shall be inert and free from shrinkage and staining. Grout bedding shall not be used with elastomeric bearings unless steel masonry plates are also used. The bearing design shall take account of induced moments and the horizontal forces induced by sliding friction, rolling friction, or deformation of a flexible element in the bearing.

11.6.1.2 Fixed and guided bearings shall be capable of resisting lateral loads in the restrained direction as required by the design, but not less than the following: (a) 10% of the vertical load capacity for bearings with a total vertical load capacity of up to 5000 kN at SLS; and (b) 500 kN, plus 5% of the vertical load exceeding 5000 kN, for bearings with a total vertical load capacity exceeding 5000 kN at SLS.

11.6.2 Metal back, roller, and spherical bearings 11.6.2.1 General design considerations The rotation axis of rocker and roller bearings shall be aligned with the axis of the largest expected rotation of the supported member. Steps shall be taken to ensure that the bearing alignment does not change during the life of the bridge. Multiple roller bearings shall be connected by gearing to ensure that individual rollers remain parallel to each other and at their original spacing.

11.6.2.2 Materials Rocker, roller, and spherical bearings shall be made of carbon steel that complies with CSA G40.20/G40.21, stainless steel that complies with ASTM A 240/A 240M, or other Approved materials.

11.6.2.3 Geometric requirements A bearing with two curved surfaces shall be symmetric about a line joining their centres of curvature. The bearing shall be designed to be stable. If the bearing consists of a roller unit with two cylindrical faces, each of which bears on a flat plate, stability shall be achieved by making the distance between the two contact surfaces not greater than the sum of the radii of the two cylindrical surfaces. The dimensions of a bearing shall be chosen to account for both the contact pressure and its movement due to rolling.

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11.6.2.4 Contact pressure The contact pressure shall be maintained at a safe level by ensuring that the SLS load, Ps , applied across metal-to-metal contact surfaces satisfies the following: (a) for cylindrical surfaces: 2

⎡ LD1 ⎤ Fy Ps ≤ 8 ⎢ D1 ⎥ E s ⎥ ⎢ 1− ⎣ D2 ⎦

(b) for spherical surfaces: 2 3 ⎡ D1 ⎤ Fy Ps ≤ 40 ⎢ D1 ⎥ E s2 ⎥ ⎢ 1− ⎣ D2 ⎦

The diameter, D2 , shall be taken as positive if the curvatures have the same sign, infinite if the mating surface is flat, and negative if the two surfaces have curvatures of opposite sign.

11.6.3 Sliding surfaces 11.6.3.1 General PTFE is used to provide sliding surfaces for bridge bearings to accommodate translation or rotation. All sliding surfaces, other than guides, shall satisfy the requirements of this Section.

11.6.3.2 PTFE layer The PTFE layer shall be made from pure virgin PTFE resin satisfying the requirements of ASTM D 4894. It shall be fabricated as unfilled sheet or filled sheet reinforced with random or woven fibres. Unfilled sheets shall be made from PTFE resin alone. Filled sheets shall be made from PTFE resin uniformly blended with glass fibres, carbon fibres, or other chemically inert fibres. The maximum filler content shall be 15% for glass fibres and 25% for carbon fibres. Sheet PTFE may contain dimples to act as reservoirs for a lubricant. The dimple diameter shall not exceed 8 mm at the surface of the PTFE, and their depth shall be not less than 2 mm and not more than half the thickness of the PTFE. The reservoirs shall be uniformly distributed over the surface area and shall cover more than 20% but less than 30% of it. The lubricant shall be silicone grease, effective to – 40 °C, and comply with U.S. Department of Defense MIL-S-8660C.

11.6.3.3 Mating surface The PTFE shall be used with a mating surface large enough to cover the PTFE at all times. For plane surfaces, the mating surface shall be stainless steel positioned above the PTFE element. For spherical surfaces, the mating surface shall be stainless steel or anodized aluminum alloy positioned above or below the PTFE element. Stainless steel shall comply with ASTM A 240/A 240 M. The roughness of the contact surface, measured in accordance with CSA B95, shall not be greater than 0.25 mm arithmetic average for plane surfaces and 0.50 mm arithmetic average for curved surfaces. The roughness of anodized aluminum machined metallic surfaces shall not exceed 0.40 mm.

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11.6.3.4 Attachment 11.6.3.4.1 PTFE layer Sheet PTFE may be confined or unconfined. Confined sheet PTFE shall be set in a recess in a rigid metal backing plate to a depth specified in Table 11.1. Unconfined sheet PTFE shall be bonded by an Approved method to a metal surface or an elastomeric layer with a Shore A durometer hardness of at least 70. Woven PTFE on a metallic substrate shall be attached to the metallic substrate by mechanical interlocking that can resist a shear force at least 0.10 times the applied compressive force.

Table 11.1 Dimensions for confined sheet PTFE (See Clauses 11.6.3.4.1 and 11.6.3.5.1.) Maximum dimension of PTFE (diameter or diagonal), mm

Minimum thickness, mm

Depth of recess, mm

≤ 1200 > 1200

5.0 5.5

2.5 3.0

11.6.3.4.2 Mating surface The mating surface for flat sliding surfaces shall be attached to a backing plate by welding in such a way that it remains flat and in full contact with the backing plate throughout its service life. The weld shall form an effective moisture seal around the entire perimeter of the mating surface so that interface corrosion cannot occur. The attachment shall be capable of resisting the maximum friction force that can be developed by the bearing. The welds used for the attachment shall be kept clear of the contact and sliding area of the PTFE surface.

11.6.3.5 Minimum thickness 11.6.3.5.1 PTFE layer For all applications, the thickness of the PTFE layer shall be at least 2 mm after compression. The minimum thickness of a confined PTFE layer shall be as specified in Table 11.1 with respect to its maximum dimension in plan.

11.6.3.5.2 Stainless steel mating surfaces The thickness of the stainless steel sheet shall be related to the dimensional difference between the stainless steel and the PTFE in the direction of movement in accordance with Table 11.2.

Table 11.2 Dimensions for stainless steel (See Clause 11.6.3.5.2.)

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Dimensional difference between PTFE and stainless steel, mm

Minimum thickness of stainless steel, mm

≤ 300 > 300 and ≤ 500 > 500 and ≤ 1500

1.5 2.0 3.0

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11.6.3.6 Contact pressure The average contact pressure between the PTFE and the mating surface shall be calculated by dividing the load by the projection of contact area onto a plane perpendicular to the direction of the load and shall not exceed the relevant maximum specified in Table 11.3. The contact area of dimpled lubricated PTFE shall be taken as the gross area of the PTFE, without deduction for the area occupied by the lubrication reservoirs. The contact pressure at the edge of the PTFE layer at SLS shall be calculated by taking into account the maximum moment transferred by the bearing, assuming a linear distribution of pressure across the PTFE layer, and shall not exceed 1.2 times the relevant maximum specified in Table 11.3.

Table 11.3 Maximum average contact pressure for PTFE, MPa (See Clauses 11.6.3.6, 11.6.7.4, and 11.6.8.6.) SLS

ULS

Material

Permanent load

All loads

Permanent load

All loads

Unconfined PTFE Unfilled sheet Filled sheet*

15 30

20 45

20 45

30 65

Confined sheet PTFE

30

45

45

65

Woven PTFE fibre over a metallic substrate

30

45

45

65

*These figures are for maximum filler content. Contact pressure for intermediate filler contents shall be obtained by linear interpolation.

11.6.3.7 Coefficient of friction The design coefficient of friction of the PTFE sliding surface shall be in accordance with Table 11.4 (using linear interpolation for any average bearing pressure at the relevant SLS that lies between the pressures specified in the Table). Where friction is required to resist applied loads, the design coefficient of friction under dynamic loading shall be taken as not more than 10% of the applicable value specified in Table 11.4.

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Table 11.4 Design coefficient of friction (See Clause 11.6.3.7.) Average bearing pressure at the SLS, MPa Material

3

7

14

> 21

Unfilled PTFE Unlubricated flat sheet Lubricated flat sheet Lubricated dimpled sheet

0.16 0.10 0.08

0.14 0.09 0.07

0.12 0.08 0.06

0.08 0.06 0.04

Filled PTFE (sheet or woven)

0.20

0.18

0.15

0.10

Woven fabric from PTFE resin

0.10

0.09

0.08

0.06

Woven fabric from PTFE fibre and metallic substrate

0.08

0.07

0.05

0.04

11.6.4 Spherical bearings 11.6.4.1 General Spherical bearings shall consist of two metal parts with matching curved surfaces and a low-friction sliding interface. The material properties, characteristics, and frictional properties of the sliding interface shall meet the requirements of Clause 11.6.3.

11.6.4.2 Geometric requirements The radius of the curved surface shall be large enough to ensure that the maximum pressure on the bearing surface satisfies the pressure limitations specified in Clause 11.6.3.6. The induced eccentricity, e, resulting from shifting in the axial load from the centre of the bearing rotation shall be calculated from e = μR. At SLS, the shift in the axial load from the centre of the bearing shall not exceed 10% of the diameter in plan of the curved sliding interface.

11.6.4.3 Lateral load capacity In bearings that are required to resist horizontal loads, an external restraint system shall be used or the radius of the curved bearing surface, R, shall satisfy

R≤

D 2 sin ( b + qu )

where the effective friction angle, β, is given by

⎡H ⎤ b = arctan ⎢ u ⎥ ⎣ Pud ⎦ The external restraint system shall permit transmission of vertical and horizontal force components without significantly restraining the rotation of the bearing.

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11.6.5 Pot bearings 11.6.5.1 General Pot bearings shall consist of a hollow metal cylinder, a confined one-piece moulded unreinforced elastomer, sealing rings, and a piston. They shall permit transmission of vertical and horizontal force components without significant restraint of rotation between the top and bottom loaded areas of the bearing. For the purpose of establishing the forces and deformations imposed on a pot bearing, the axis of rotation shall be taken as lying in the horizontal plane at the interface between the elastomer and piston.

11.6.5.2 Materials The elastomer disc shall be made from a compound based on virgin polyisoprene or polychloroprene. Its nominal hardness shall lie between 50 and 60 on the Shore A scale. Preference shall be given to polyisoprene for use in low-temperature regions. The pot and piston shall be made from carbon steel that complies with CSA G40.20/G40.21, Grade 260W, 300W, or 350A; stainless steel that complies with ASTM A 240/A 240M; or other Approved materials. The piston shall not be made from a steel with a higher yield strength than that of the pot. Sealing rings shall be made from brass that complies with ASTM B 36/B 36M, half-hard (for rings of rectangular cross-section) and ASTM B 121, Composition 2 (for rings of circular cross-section).

11.6.5.3 Geometric requirements The pot shall be deep enough for the seal and piston rim to remain in full contact with the vertical face of the pot wall. Provision for rotation about any horizontal axis shall be by deformation of the elastomer. The rotation of the elastomer about a horizontal axis shall be limited so that the vertical strain induced at the perimeter of the elastomer at SLS shall not exceed 15% of the elastomer thickness. A pot bearing shall be loaded with at least 25% of the SLS load in order to provide satisfactory rotational operation. The induced eccentricity, e, as a result of shifting of the axial load from the centre of the bearing under the maximum rotation at SLS shall not exceed 4% of the diameter of the elastomer.

11.6.5.4 Elastomeric disc The average pressure on the elastomer at SLS shall not exceed 40 MPa. All surfaces of the elastomer shall be treated with a lubricant that is not detrimental to the elastomer.

11.6.5.5 Sealing rings 11.6.5.5.1 General A seal shall be used between the pot and the piston. At SLS, the seal shall be designed to prevent escape of elastomer under compressive load and simultaneously applied cyclic rotations. At ULS, it shall also be sufficient to prevent escape of elastomer under the compressive load and simultaneously applied static rotation. These requirements shall be deemed satisfied if the sealing rings meet the requirements of Clause 11.6.5.5.2 or 11.6.5.5.3. The Engineer may approve other sealing systems on the basis of experimental evidence.

11.6.5.5.2 Rings with rectangular cross-section When the cross-section of the rings is rectangular, three rings shall be used. Each ring shall be circular in plan and shall be cut at one point around its circumference. The faces of the cut shall be bevelled at 45° to the vertical. The rings shall be oriented so that the three cuts are equally spaced around the circumference of the pot. The width of each ring shall be equal to or greater than the larger of 0.02Dp and 6 mm, but shall not exceed 20 mm. The depth of each ring shall be equal to or greater than the larger of 0.2 times the width and 1 mm.

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11.6.5.5.3 Rings with circular cross-section When the cross-section of the rings is circular, one circular closed ring with an outside diameter of Dp shall be used. It shall have a cross-sectional diameter equal to or greater than the larger of 0.0175Dp and 4 mm.

11.6.5.6 Pot The pot shall consist of a wall and a base. All of the components of the pot shall be designed to act structurally as a single unit. The thickness of the base shall be equal to or greater than the larger of 0.06Dp and 20 mm when bearing directly on concrete or grout, and equal to or greater than the larger of 0.04Dp and 15 mm when bearing directly on steel girders or load distribution plates. At ULS, the pot wall shall be thick enough to resist all induced forces. In lieu of rigorous analysis, this requirement may be satisfied for unguided sliding pot bearings by using a wall thickness, tw , as follows:

tw ≥

Dp 2f Fy

pu

The wall thickness of guided or fixed pot bearings shall be determined by rigorous analysis.

11.6.5.7 Piston The piston shall have the same plan shape as the inside of the pot. The piston shall be thick enough to resist the loads imposed on it, but not less than 0.06Dp thick. The perimeter of the piston shall have a rim through which horizontal loads can be transmitted. The diameter of the piston rim shall be smaller than Dp by 0.5 to 1.25 mm. The piston perimeter above the rim shall be set back or tapered to prevent binding. The height, w, of the piston rim shall be large enough to transmit the horizontal forces between the pot and the piston, assuming a contact area of 0.33wDp and a maximum bearing pressure of φ Fy . w shall not be less than the smaller of 0.03Dp and 6 mm.

11.6.6 Elastomeric bearings 11.6.6.1 General Elastomeric bearings may be plain bearings consisting entirely of elastomer or laminated bearings with embedded laminae consisting of alternating layers of elastomer and lamina.

11.6.6.2 Materials 11.6.6.2.1 Laminae Laminae shall be made of rolled mild steel with a minimum yield strength of 230 MPa or another Approved material.

11.6.6.2.2 Elastomers Elastomers shall meet the following requirements: (a) virgin natural polyisoprene and virgin polychloroprene shall be the only raw polymers allowed; (b) the physical properties of vulcanized elastomer shall be determined using test specimens taken from sample bearings; and (c) the physical properties of any polyisoprene and polychloroprene shall be in accordance with the requirements specified in Table 11.5.

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Table 11.5 Physical properties of polyisoprene and polychloroprene (See Clause 11.6.6.2.2.) Requirement Property

Test

Polyisoprene

Polychloroprene

Hardness, °Shore A

ASTM D 2240

55 ± 5

55 ± 5

Tensile strength, MPa

ASTM D 412

Minimum 17.0

Minimum 17.0

Ultimate elongation, %

ASTM D 412

Minimum 400

Minimum 400

Heat resistance

ASTM D 573

70 h at 70 °C

70 h at 100 °C

Change in hardness, °Shore A

Maximum +10

Maximum +15

Change in tensile strength, %

Maximum –25

Maximum –15

Change in ultimate elongation, %

Maximum –25

Maximum – 40

Compression set, %

ASTM D 395, Method B

22 h at 70 °C, maximum 25

22 h at 100 °C, maximum 35

Ozone resistance

ASTM D 1149, Mounting Procedure A, 20% strain, 40 ± 2 °C

25 pphm, 48 h, no cracks

100 pphm, 100 h, no cracks

Bond between steel and elastomer laminae, N•mm–1

ASTM D 429, Method B

Minimum 7.0

Minimum 7.0

Brittleness at – 40 °C

ASTM D 746, Procedure B

No failure

No failure

Low temperature crystallization increase in hardness, °Shore A

ASTM D 2240

168 h at –25 °C, maximum +15

168 h at –10 °C, maximum +15

11.6.6.3 Geometric requirements Bearings shall have the following proportions to ensure stability: (a) for plain bearings: L ≥ 5he and R ≥ 3he , with 10 mm < he < 30 mm; and (b) for laminated bearings: L ≥ 3he and R ≥ 2he . An elastomeric bearing pad in form of a single continuous strip may be used only under precast slabs placed side by side or under a cast-in-place slab, provided that the bearing pressure meets the requirements of Clause 11.6.6.7.

11.6.6.4 Deformation and rotation Translation shall be accommodated by the shear deformation of the elastomer. Rotation shall be accommodated by the vertical deformation of the elastomer. The average compressive deformation of the effective elastomer thickness shall not exceed 0.07he at SLS. Where rotation occurs, the bearing shall be proportioned so that there is no uplift corresponding to a maximum edge deformation of 0.14he at the edge of the bearing at SLS. The shear deformation in any direction shall not exceed 0.5he at SLS.

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11.6.6.5 Fabrication 11.6.6.5.1 Plain bearings Plain bearing pads shall be moulded individually, cut from previously moulded strips or slabs of the required thickness, or extruded and cut to length.

11.6.6.5.2 Laminated bearings Laminated bearings shall be moulded as a single unit under pressure and heat in moulds that produce a smooth surface finish. Steel laminae shall meet the following requirements: (a) all laminae and elastomer layers shall be of uniform thickness; (b) internal steel plates or laminae shall be free from sharp edges; (c) laminae shall be completely bonded on all surfaces to the elastomeric material during moulding; and (d) where pintles are specified, pintle holes shall be of such a depth as to fully engage only one lamina. Cover over pintle holes shall not be required. The elastomeric cover on the side surfaces shall be at least 5 mm thick. The elastomeric cover of the outer layers, top and bottom, shall not be thicker than 70% of the thickness of an individual internal elastomeric layer.

11.6.6.6 Positive attachment To prevent displacement of the bearing, positive attachment shall be provided if either of the following conditions exists: (a) the shear force generated by the bearing exceeds the frictional resistance between the structure and the loaded faces of the bearing; or (b) the minimum average pressure on the bearing is less than 1.5 MPa under SLS. A continuous strip of elastomeric bearing pad meeting the requirements of Clause 11.6.6.3 shall not require positive attachment.

11.6.6.7 Bearing pressure At SLS under permanent loads, the average pressure on a laminated bearing and the average pressure on a layer of elastomer shall not exceed 4.5 MPa. At SLS under all loading combinations, the average pressure on a laminated bearing shall not exceed 7.0 MPa. At SLS, the average pressure on a layer of elastomer, assuming no rotation, shall not exceed the permitted pressure indicated in Figure 11.1 with respect to the shape factor of the layer. The shape factor shall be based on the thickest layer within the laminated bearing. At ULS under permanent loads, the average pressure on a laminated bearing shall not exceed 7.0 MPa. At ULS under all loading combinations, the average pressure on a laminated bearing shall not exceed 10.0 MPa.

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Bearing does not meet the requirements of Clause 11.6.6.7

7 6

Average pressure, MPa

5 Bearing meets the requirements of Clause 11.6.6.7

4 3 2 1 0

Positive attachment required (Clause 11.6.6.6) 0

1 1.25

2

3

4

5

6

Shape factor, S

Note: Average pressure = 0.22S2.

Figure 11.1 Maximum average pressure on a layer of elastomeric bearing at SLS without rotation (See Clause 11.6.6.7.)

11.6.7 Disc bearings 11.6.7.1 General Disc bearings shall consist of a restrained single moulded disc of unreinforced elastomer, upper and lower metal bearing plates, and a shear-restriction mechanism and shall permit transmission of vertical and horizontal force components without significant restraint of rotation between the top and bottom loaded areas of the bearing. For the purpose of establishing the forces and deformations imposed on a disc bearing, the axis of rotation may be taken as lying in the horizontal plane at mid-height of the disc. The disc shall be held in place by a positive location device.

11.6.7.2 Materials The elastomeric disc shall be made from a compound based on polyether urethane, using only virgin materials. The hardness shall lie between 45 and 65 on the Shore D scale. The metal components of the bearing shall be made from carbon steel meeting the requirements of CSA G40.20/G40.21, stainless steel meeting the requirements of ASTM A 240/A 240M, or other Approved materials.

11.6.7.3 Geometric requirements The induced eccentricity as a result of the shift in the axial load from the centre of the bearing under the maximum bearing rotation at SLS shall not exceed 10% of the diameter of the elastomeric disc.

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The horizontal clearance between the upper and lower components of the shear-restricting mechanism shall not exceed the value for guide bars specified in Clause 11.6.8.3.

11.6.7.4 Elastomeric disc The disc shall be designed so that under SLS (a) its instantaneous deflection under total load does not exceed 10% of the unstressed disc thickness and the additional deflection due to creep does not exceed 8% of the unstressed disc thickness; (b) the components of the bearing always remain in contact; (c) the average compressive pressure on the disc does not exceed 35 MPa; and (d) the pressure on the PTFE sliding surface (if such a surface exists) does not exceed the allowable values for pressures specified in Table 11.3. In addition, the effect of moment induced by deformation of the disc shall be included in the stress analysis. This moment is the result of the induced eccentricity, e, due to shift in the axial load.

11.6.7.5 Steel plates The thickness of both the upper and the lower steel plate shall not be less than 0.045Dd if they are in direct contact with a steel girder or distribution plate or 0.06Dd if they bear directly on grout or concrete.

11.6.8 Guides for lateral restraints 11.6.8.1 General Guides shall be used to restrict movement of the structure in one direction and shall have a low-friction material at their sliding contact surfaces. The seismic design considerations specified in Section 4 shall be applied as necessary.

11.6.8.2 Materials Guides shall conform to the material requirements of the bearing specified in Clauses 11.6.5.2, 11.6.2.2, and 11.6.6.2, as applicable.

11.6.8.3 Geometric requirements Guide bars shall be parallel, long enough to accommodate the full design movement of the structure in the sliding direction, and have a clearance of 1.5 mm in the restrained direction.

11.6.8.4 Design loads Guides shall be designed for the lateral loads specified in Clause 11.6.1.

11.6.8.5 Load location The horizontal load acting on a guide shall be assumed to act at the centroid of the low-friction sliding interface material. The design of the connection between the guide and the body of the bearing system shall take into account shear and the induced overturning moments.

11.6.8.6 Contact pressure The contact pressure on the low-friction material shall not exceed that recommended by the manufacturer. For PTFE, the pressure shall not exceed the applicable value specified in Table 11.3.

11.6.8.7 Attachment of low-friction material Low-friction material shall be attached using at least two of the following methods: (a) mechanical fastening; (b) bonding; (c) mechanical interlocking with a metal substrate; and (d) recessing.

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11.6.9 Other bearing systems Bearing systems made from components not covered by Clauses 11.6.2 to 11.6.8 may also be used, subject to Approval. Such bearings shall meet the requirements of Clause 11.6.1.

11.6.10 Load plates and attachment for bearings 11.6.10.1 Plates for load distribution The bearing, together with any additional plates, shall be designed so that (a) the combined system is stiff enough to prevent distortions of the bearing that would impair its proper functioning; and (b) the bearing resistance of the concrete satisfies the requirements of Section 8. In lieu of a more precise analysis, the loads from the bearing may be assumed to disperse at a slope of 1.5:1, horizontal to vertical, from the edge of the smallest element of the bearing that carries the compressive load.

11.6.10.2 Tapered plates Where necessary, a tapered plate shall be used to provide a level load surface on a bearing.

11.6.10.3 Attachment All load distribution plates shall be positively secured to the superstructure or the substructure by bolting, welding, or anchoring. Connections shall be designed in accordance with the applicable Sections of this Code.

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Section 12 — Barriers and highway accessory supports 12.1 12.2 12.3 12.3.1 12.3.2 12.4 12.4.1 12.4.2 12.4.3 12.4.4 12.4.5 12.4.6 12.5 12.5.1 12.5.2 12.5.3 12.5.4 12.5.5 12.5.6 12.5.7 12.5.8 12.5.9 12.5.10 12.5.11

Scope 552 Definitions 552 Abbreviations and symbols 553 Abbreviations 553 Symbols 553 Barriers 554 General 554 Barrier joints 554 Traffic barriers 554 Pedestrian barriers 562 Bicycle barriers 563 Combination barriers 564 Highway accessory supports 564 General 564 Vertical clearances 564 Maintenance 564 Aesthetics 564 Design 564 Breakaway supports 566 Foundations 566 Corrosion protection 567 Minimum thicknesses 567 Camber 567 Connections 567

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Section 12 Barriers and highway accessory supports 12.1 Scope This Section specifies requirements for the design of permanent bridge barriers and highway accessory supports.

12.2 Definitions The following definitions apply in this Section: Anchorage — a bolt, stud, reinforcing bar, or assembly that is installed in concrete to anchor a structure or a component. Average annual daily traffic (AADT) — the total volume of traffic during a year divided by the number of days in the year. Barrier clearance — the clearance between the outside edge of the traffic lanes and the roadway face of a barrier. Barrier exposure index — an index that reflects traffic volumes and bridge site characteristics and is used for determining barrier performance levels. Barrier joint — a discontinuity in a barrier that permits relative rotation or translation between barrier components on opposite sides of the discontinuity. Bikeway — part of a highway designated for the movement of bicycles. Breakaway support — a support designed to fail in such a way that, when struck by a vehicle, damage to the vehicle and injury to its occupants does not exceed a specified level. Cantilevered support — a support that cantilevers out over a roadway. Crash cushion — a barrier used for protecting vehicles from a roadside hazard and designed to fail in such a way that, when struck by a vehicle, damage to the vehicle and injury to its occupants does not exceed a specified level. Crash test — a test of a barrier or highway accessory support carried out by crashing a vehicle into it and monitoring the vehicle-barrier or vehicle–highway accessory support interaction. Design speed — the speed for which a highway at a bridge site is designed. Highway accessory — a component required for the operation of a highway, e.g., a sign, luminaire, traffic signal, surveillance installation, noise barrier, or privacy barrier. Highway accessory support — a structure (including supporting brackets, maintenance walkways, and mechanical devices, where present) that is designed to support highway accessories. Luminaire — a complete lighting fixture (including the light source, reflector, refractor, housing, and ballast, where present, but excluding support members).

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Overhead support — a support that has a member on each side of a roadway supporting a horizontal member that spans over the roadway. Performance level — the specified level to which a traffic barrier is to perform in reducing the consequences of a vehicle leaving the roadway, as required by the applicable crash test requirements (see Clauses 12.4.3.2 and 12.4.3.4). Performance Level 1 (PL-1) — the performance level for traffic barriers on bridges where the expected frequency and consequences of vehicles leaving the roadway are similar to those expected on low-traffic-volume roads. For PL-1, the AASHTO Guide Specifications for Bridge Railings (see Clause 12.4.3.4.2) require crash testing with a small automobile and a pickup truck. Performance Level 2 (PL-2) — the performance level for traffic barriers on bridges where the expected frequency and consequences of vehicles leaving the roadway are similar to those expected on high-to-moderate-traffic-volume highways. For PL-2, the AASHTO Guide Specifications for Bridge Railings (see Clause 12.4.3.4.2) require crash testing with a small automobile, a pickup truck, and a single-unit truck. Performance Level 3 (PL-3) — the performance level for traffic barriers on bridges where the expected frequency and consequences of vehicles leaving the roadway are similar to those expected on high-traffic-volume highways with high percentages of trucks. For PL-3, the AASHTO Guide Specifications for Bridge Railings (see Clause 12.4.3.4.2) require crash testing with a small automobile, a pickup truck, and a tractor-trailer truck. Post and railing barrier — an open barrier consisting of railings that follow the profile of a bridge and posts that support the railings at discrete locations. Roadside support — a support adjacent to a roadway, with no part of the support or its accessory extending over the roadway. Sign — a panel for displaying messages. Traffic barrier termination — the start or end point of a longitudinal run of traffic barrier. Traffic barrier transition — the portion of an approach roadway traffic barrier that is adjacent to a bridge traffic barrier and provides a transition between the two barrier types. Traffic signal — a complete signal device consisting of traffic lights and housing.

12.3 Abbreviations and symbols 12.3.1 Abbreviations The following abbreviations apply in this Section: PL-1 — Performance Level 1 PL-2 — Performance Level 2 PL-3 — Performance Level 3

12.3.2 Symbols The following symbols apply in this Section: AADT1 = average annual daily traffic for the first year after construction Be

= barrier exposure index

H

= height of barrier, m

Kc

= highway curvature factor

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Kg

= highway grade factor

Kh

= highway type factor

Ks

= superstructure height factor

L

= span of overhead and cantilevered support members, m

Pl

= longitudinal traffic load on barrier, kN

Pt

= transverse traffic load on barrier, kN

Pv

= vertical traffic load on barrier, kN

Wp

= pedestrian or bicycle load on barrier, kN or kN/m

© Canadian Standards Association

12.4 Barriers 12.4.1 General Barriers shall be classified as traffic, pedestrian, bicycle, or combination barriers according to their function. In addition to the requirements of Clauses 12.4.2 to 12.4.6, the following factors shall be considered in the appraisal of a barrier: (a) durability; (b) ease of repair; (c) snow accumulation on and snow removal from deck; (d) visibility through or over barrier; (e) deck drainage; (f) future wearing surfaces; and (g) aesthetics.

12.4.2 Barrier joints Barrier joints shall be detailed to allow for the movements specified in Section 3.

12.4.3 Traffic barriers 12.4.3.1 General Traffic barriers shall be provided on both sides of highway bridges to delineate the superstructure edge and to reduce the consequences of vehicles leaving the roadway. Barrier adequacy in reducing the consequences of vehicles leaving the roadway shall be determined from crash tests, except that the adequacy of a barrier that has the same details as those of an existing traffic barrier may be determined from an evaluation of the existing barrier’s performance when struck by vehicles.

12.4.3.2 Performance level 12.4.3.2.1 General The performance level used for a bridge site shall be Performance Level 1, 2, or 3, determined in accordance with Clauses 12.4.3.2.3 and 12.4.3.2.4, unless alternative performance levels are Approved in accordance with Clause 12.4.3.2.2.

12.4.3.2.2 Alternative performance levels Performance levels other than Performance Levels 1, 2, and 3 shall be Approved by the Regulatory Authority for the bridge and shall be defined by specifying their crash test requirements. These alternative performance levels shall be considered along with Performance Levels 1, 2, and 3 when the optimum performance level for a bridge site is being determined. The optimum performance level shall be taken to

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be the performance level with the least costs, where the costs for each performance level include the costs of supplying and maintaining an appropriate traffic barrier as well as the costs of all accidents expected with the use of that barrier.

12.4.3.2.3 Determination of barrier exposure index The barrier exposure index used for determining the performance level shall be based on the estimated average annual daily traffic for the first year after construction, AADT1, which shall be limited to a maximum value of 10 000 vehicles per day per traffic lane for vehicle speeds of 80 km/h or greater. AADT1 shall be multiplied by highway type, highway curvature, highway grade, and superstructure height factors to calculate the barrier exposure index, as follows:

Be =

( AADT1) K hK c K gK s 1000

The highway type, highway curvature, highway grade, and superstructure height factors shall be as specified in Tables 12.1 to 12.4.

Table 12.1 Highway type factors, Kh (See Clause 12.4.3.2.3.) Highway type

Design speed, km/h

Kh

One-way*

50–110

2.00

Two-way divided†

50–110

1.00

Two-way undivided, with five or more lanes†‡

50–110

1.00

Two-way undivided, with four or fewer lanes†‡§

50 60 80 100 110

1.20 1.30 1.45 1.60 1.65

*AADT1 is based on one-way traffic. †AADT1 is based on two-way traffic. ‡Number of lanes refers to total number of lanes on bridge. §Interpolate highway type factors for design speeds not given.

Table 12.2 Highway curvature factors, Kc (See Clause 12.4.3.2.3.) Radius of curve, m*

Barrier on outside of curve, Kc

Barrier on inside of curve, Kc

≤ 300 350 400 450 500 550 ≥ 600

4.00 3.00 2.40 1.90 1.50 1.20 1.00

2.00 1.65 1.45 1.30 1.15 1.05 1.00

*Interpolate highway curvature factors for radii of curves not given.

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Table 12.3 Highway grade factors, Kg (See Clause 12.4.3.2.3.) Grade, %*†

Kg

≥ –2 –3 –4 –5 ≤ –6

1.00 1.25 1.50 1.75 2.00

*Positive grade increases in the direction that traffic is travelling. †Interpolate highway grade factors for grades not given.

Table 12.4 Superstructure height factors, Ks (See Clause 12.4.3.2.3.)

Superstructure height above ground or water surface, m* ≤5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ≥ 24

Ks High-occupancy land use† or deep water‡ beneath bridge

Low-occupancy land use or shallow water beneath bridge

0.70 0.80 0.90 1.00 1.15 1.25 1.35 1.50 1.60 1.70 1.85 1.95 2.05 2.20 2.30 2.40 2.85

0.70 0.70 0.70 0.70 0.80 0.95 1.05 1.20 1.30 1.45 1.55 1.70 1.80 1.95 2.05 2.20 2.70

*Interpolate superstructure height factors for superstructure heights not given. †Includes highways or railways beneath bridge. ‡Water deeper than 3 m.

12.4.3.2.4 Determination of performance level Except when alternative performance levels are Approved in accordance with Clause 12.4.3.2.2, the optimum performance level to be used for a traffic barrier shall be determined from Tables 12.5 to 12.7. When alternative performance levels are Approved, the optimum performance level shall be determined in accordance with Clause 12.4.3.2.2. Consideration shall be given to the use of an increased design speed whenever the design speed at a bridge site is not limited by highway alignment or roadway surface.

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Table 12.5 Optimum performance levels — Barrier clearance less than or equal to 2.25 m (See Clause 12.4.3.2.4.)

Design speed, km/h

November 2006

Barrier exposure index Trucks, %

PL-1

PL-2

PL-3

50

0 5 10 15 20 25 40

< 224.8 < 75.2 < 32.0 < 20.5 < 15.1 < 12.0 < 7.4

≥ 224.8 ≥ 75.2 32.0–222.5 20.5–126.3 15.1–88.3 12.0–67.7 7.4–40.0

— — > 222.5 > 126.3 > 88.3 > 67.7 > 40.0

60

0 5 10 15 20 25 40

< 53.2 < 27.4 < 16.5 < 12.0 < 9.6 < 7.8 < 5.2

≥ 53.2 ≥ 27.4 16.5–111.3 12.0–63.8 9.6–44.8 7.8–34.4 5.2–20.4

— — > 111.3 > 63.8 > 44.8 > 34.4 > 20.4

80

0 5 10 15 20 25 40

< 7.2 < 6.3 < 5.4 < 4.8 < 4.3 < 3.9 < 3.0

≥ 7.2 6.3–188.6 5.4–61.4 4.8–36.7 4.3–26.1 3.9–20.3 3.0–12.2

— > 188.6 > 61.4 > 36.7 > 26.1 > 20.3 > 12.2

100

0 5 10 15 20 25 40

< 3.1 < 2.9 < 2.8 < 2.6 < 2.5 < 2.4 < 2.2

≥ 3.1 2.9–113.2 2.8–44.8 2.6–28.0 2.5–20.3 2.4–15.9 2.2–9.7

— > 113.2 > 44.8 > 28.0 > 20.3 > 15.9 > 9.7

110

0 5 10 15 20 25 40

< 2.4 < 2.3 < 2.3 < 2.2 < 2.1 < 2.0 < 1.9

≥ 2.4 2.3–84.9 2.3–39.4 2.2–25.6 2.1–19.0 2.0–15.1 1.9–9.4

— > 84.9 > 39.4 > 25.6 > 19.0 > 15.1 > 9.4

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Table 12.6 Optimum performance levels — Barrier clearance greater than 2.25 m and less than or equal to 3.75 m (See Clause 12.4.3.2.4.)

Design speed, km/h

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Barrier exposure index Trucks, % PL-1

PL-2

PL-3

50

0 5 10 15 20 25 40

— < 121.5 < 48.2 < 30.3 < 22.2 < 17.5 < 10.7

— ≥ 121.5 48.2–350.1 30.3–198.8 22.2–138.8 17.5–106.6 10.7–62.9

— — > 350.1 > 198.8 > 138.8 > 106.6 > 62.9

60

0 5 10 15 20 25 40

< 76.6 < 39.5 < 22.6 < 16.3 < 12.7 < 10.6 < 6.9

≥ 76.6 ≥ 39.5 22.6–171.3 16.3–99.7 12.7–70.3 10.6–54.2 6.9–32.3

— — > 171.3 > 99.7 > 70.3 > 54.2 > 32.3

80

0 5 10 15 20 25 40

< 9.9 < 8.4 < 7.2 < 6.3 < 5.6 < 5.0 < 3.8

≥ 9.9 8.4–247.3 7.2–70.6 6.3–41.2 5.6–29.1 5.0–22.5 3.8–13.4

— > 247.3 > 70.6 > 41.2 > 29.1 > 22.5 > 13.4

100

0 5 10 15 20 25 40

< 3.6 < 3.5 < 3.4 < 3.3 < 3.2 < 3.0 < 2.7

≥ 3.6 3.5–140.4 3.4–49.8 3.3–30.3 3.2–21.8 3.0–16.9 2.7–10.2

— > 140.4 > 49.8 > 30.3 > 21.8 > 16.9 > 10.2

110

0 5 10 15 20 25 40

< 2.8 < 2.7 < 2.7 < 2.6 < 2.6 < 2.5 < 2.4

≥ 2.8 2.7–102.7 2.7–43.2 2.6–27.4 2.6–20.1 2.5–15.8 2.4–9.6

— > 102.7 > 43.2 > 27.4 > 20.1 > 15.8 > 9.6

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Table 12.7 Optimum performance levels — Barrier clearance greater than 3.75 m (See Clause 12.4.3.2.4.)

Design speed, km/h

November 2006

Barrier exposure index Trucks, % PL-1

PL-2

PL-3

50

0 5 10 15 20 25 40

— < 255.1 < 85.5 < 51.9 < 37.2 < 29.1 < 17.5

— ≥ 255.1 ≥ 85.5 51.9–394.1 37.2–274.9 29.1–211.0 17.5–124.4

— — — > 394.1 > 274.9 > 211.0 > 124.4

60

0 5 10 15 20 25 40

< 139.4 < 71.8 < 36.3 < 25.1 < 19.3 < 15.7 < 10.1

≥ 139.4 ≥ 71.8 36.3–260.5 25.1–151.6 19.3–106.0 15.7–81.5 10.1–48.1

— — > 260.5 > 151.6 > 106.0 > 81.5 > 48.1

80

0 5 10 15 20 25 40

< 13.0 < 11.2 < 9.6 < 8.4 < 7.5 < 6.7 < 5.2

≥ 13.0 11.2–314.7 9.6–88.5 8.4–51.5 7.5–36.3 6.7–28.1 5.2–16.7

— > 314.7 > 88.5 > 51.5 > 36.3 > 28.1 > 16.7

100

0 5 10 15 20 25 40

< 4.4 < 4.1 < 4.0 < 3.9 < 3.7 < 3.6 < 3.2

≥ 4.4 4.1–181.5 4.0–63.4 3.9–38.4 3.7–27.5 3.6–21.5 3.2–12.9

— > 181.5 > 63.4 > 38.4 > 27.5 > 21.5 > 12.9

110

0 5 10 15 20 25 40

< 3.2 < 3.1 < 3.0 < 3.0 < 3.0 < 2.9 < 2.8

≥ 3.2 3.1–135.2 3.0–54.5 3.0–34.2 3.0–24.8 2.9–19.5 2.8–11.9

— > 135.2 > 54.5 > 34.2 > 24.8 > 19.5 > 11.9

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Table 12.8 Minimum barrier heights, H* (See Clauses 12.4.3.3, 12.4.4.2, and 12.4.5.2.) Type of barrier

H, m

Traffic PL-1

0.68

PL-2

0.80

PL-3

1.05†

Combination (pedestrian)

1.05

Combination (bicycle)

1.37

Pedestrian

1.05

Bicycle

1.37

*The height of the barrier is the vertical distance from the top to the bottom of the roadway, sidewalk, or bikeway face of the barrier, as applicable. For combination barriers, the height of the barrier is measured on the sidewalk or bikeway face of the barrier. †For freeways and high-speed rural arterial highways, consideration shall be given to increasing the barrier height to 1.37 m.

12.4.3.3 Geometry and end treatment details The roadway face of a traffic barrier shall have a smooth continuous alignment and a smooth transition into the roadway face of the approach roadway traffic barrier (where one is present). Where no approach roadway traffic barrier is present, traffic barrier termination details shall be consistent with the roadside safety standards of the approach roadway. Traffic barriers shall comply with the minimum height requirements specified in Table 12.8. Where a traffic barrier is located between the roadway and a sidewalk or bikeway, the sidewalk or bikeway face of the barrier shall have a smooth surface without snag points and a minimum height of 0.60 m measured from the surface of the sidewalk or bikeway.

12.4.3.4 Crash test requirements 12.4.3.4.1 General The traffic barrier crash test requirements specified in Clause 12.4.3.4.2 shall be satisfied along the entire length of a traffic barrier, including at the locations of any changes in barrier type, shape, alignment, or strength that could affect barrier performance. When a traffic barrier is to be placed on a bridge curb or sidewalk, the traffic barrier crash test requirements shall be satisfied with the barrier placed on a similar curb or sidewalk.

12.4.3.4.2 Crash test requirements for traffic barriers Except as specified in Clauses 12.4.3.4.4 and 12.4.3.4.5, traffic barriers shall meet the crash test requirements of the optimum performance level determined in accordance with Clause 12.4.3.2, or of a more severe performance level if considered desirable.

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The crash test requirements for traffic barriers for Performance Levels 1, 2, and 3 shall be the crash test requirements specified in the AASHTO Guide Specifications for Bridge Railings. The crash test requirements for performance levels other than Performance Levels 1, 2, and 3 shall be Approved in accordance with Clause 12.4.3.2.2.

12.4.3.4.3 Crash test requirements for traffic barrier transitions Except as specified in Clauses 12.4.3.4.4 and 12.4.3.4.5, traffic barrier transitions shall meet the crash test requirements used for appraising the approach roadway traffic barrier.

12.4.3.4.4 Alternative crash test requirements A traffic barrier or traffic barrier transition shall be assumed to have met the requirements of Clauses 12.4.3.4.2 and 12.4.3.4.3, respectively, if it has been crash tested to requirements that test its geometry, strength, and behaviour to an equivalent or more severe level than the requirements of Clauses 12.4.3.4.2 and 12.4.3.4.3, respectively. The crash test requirements for longitudinal barrier Test Levels 2, 4, and 5 of NCHRP Report 350 shall be taken as meeting the crash test requirements for Performance Levels 1, 2, and 3, respectively.

12.4.3.4.5 Changes to crash-tested traffic barriers and traffic barrier transitions Changes to the details of a traffic barrier or traffic barrier transition that meets the requirements of Clauses 12.4.3.4.2 to 12.4.3.4.4 may be made, provided that any changes affecting the geometry, strength, or behaviour of the traffic barrier or traffic barrier transition can be demonstrated to not adversely affect vehicle-barrier interaction.

12.4.3.5 Anchorages The suitability of a traffic barrier anchorage shall be based on its performance during crash testing of the traffic barrier. For an anchorage to be considered acceptable, significant damage shall not occur in the anchorage or deck during crash testing. If crash testing results for the anchorage are not available, the anchorage and deck shall be designed to resist the maximum bending, shear, and punching loads that can be transmitted to them by the traffic barrier, except that these loads need not be taken as greater than those resulting from the loads specified in Clause 3.8.8 and applied as shown in Figure 12.1.

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Pv

600 — PL-1 700 — PL-2 900 — PL-3

600 — PL-1 700 — PL-2 900 — PL-3

600 — PL-1 700 — PL-2 900 — PL-3

Top of riding or wearing surface (typical)

Pt

Pt

Pt

Pv

Pv

Notes: (1) Traffic barrier types are illustrative only and other types may be used. (2) Transverse load Pt shall be applied over a barrier length of 1200 mm for PL-1 barriers, 1050 mm for PL-2 barriers, and 2400 mm for PL-3 barriers. (3) Longitudinal load Pl shall be applied at the same locations and over the same barrier lengths as Pt . For post and railing barriers, the longitudinal load shall not be distributed to more than three posts. (4) Vertical load Pv shall be applied over a barrier length of 5500 mm for PL-1 and PL-2 barriers and 12 000 mm for PL-3 barriers. (5) These loads shall be used for the design of traffic barrier anchorages and decks only.

Figure 12.1 Application of traffic design loads to traffic barriers (See Clause 12.4.3.5.)

12.4.4 Pedestrian barriers 12.4.4.1 General Pedestrian barriers shall be provided on both sides of pedestrian bridges and on the outside edges of highway bridge sidewalks separated from the roadway by a traffic barrier.

12.4.4.2 Geometry Pedestrian barriers shall comply with the minimum height requirements specified in Table 12.8. Openings in pedestrian barriers shall not exceed 150 mm in the least direction or shall be covered with chain link mesh. Openings in chain link mesh shall not be larger than 50 × 50 mm. The wires making up the mesh shall have a minimum diameter of 3.5 mm.

12.4.4.3 Design loading The design loading for pedestrian barriers shall be as specified in Clause 3.8.8 and the loads applied shall be as shown in Figure 12.2. Only one railing shall be loaded at a time when posts of post-and-railing barriers are being designed.

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Wp

Wp

Wp

Wp

Wp

Wp Wp

Wp

Chain link mesh

Vertical bar Parapet

Wp

Wp Wp

Wp

Sidewalk or bikeway surface Note: Traffic barrier types are illustrative only and other types may be used.

Figure 12.2 Application of pedestrian and bicycle design loads to barriers (See Clauses 12.4.4.3 and 12.4.5.3.)

12.4.5 Bicycle barriers 12.4.5.1 General Bicycle barriers shall be provided on both sides of bicycle bridges and on the outside edges of highway bridge bikeways where the bikeway is separated from the roadway by a traffic barrier.

12.4.5.2 Geometry Bicycle barriers shall comply with the minimum height requirements specified in Table 12.8. Openings in bicycle barriers for the lower 1050 mm of barrier shall not exceed 150 mm in the least direction or shall be covered with chain link mesh. Openings in chain link mesh shall not be larger than 50 × 50 mm. The wires making up the mesh shall have a minimum diameter of 3.5 mm.

12.4.5.3 Design loading The design loading for bicycle barriers shall be as specified in Clause 3.8.8 and the loads applied shall be as shown in Figure 12.2. Only one railing shall be loaded at a time when posts of post-and-railing barriers are being designed.

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12.4.6 Combination barriers 12.4.6.1 General Combination barriers shall be provided on the outside edges of bridge sidewalks and bikeways not separated from the traffic lanes by a traffic barrier. They shall meet the requirements of Clause 12.4.3 as well as the requirements of Clauses 12.4.4 and 12.4.5, as applicable to the type of barrier, except as specified in Clause 12.4.6.2.

12.4.6.2 Geometry Openings in combination barriers shall be less than or equal to 150 mm in the least direction for the lower 600 mm of barrier and 380 mm in the least direction above the lower 600 mm of barrier.

12.5 Highway accessory supports 12.5.1 General When required by roadside safety standards, highway accessory supports shall be designed as breakaway supports or protected from traffic by a barrier or crash cushion. Breakaway supports shall not be used in situations where they are likely to fall across the roadway after being struck by a vehicle.

12.5.2 Vertical clearances Vertical clearances over roadways shall comply with Clause 1.5.2.2.

12.5.3 Maintenance Suitable access for maintaining and repairing highway accessories and their supports with minimal disruption to traffic shall be provided.

12.5.4 Aesthetics The aesthetics of highway accessories and their supports shall be considered, with due regard for the surrounding environment.

12.5.5 Design 12.5.5.1 General Wind loads on highway accessory supports shall be in accordance with Annex A3.2.

12.5.5.2 Ultimate limit states 

12.5.5.2.1 General The factored resistances of concrete, wood, steel, and aluminum components and connections shall be determined in accordance with Sections 8, 9, 10, and 17, respectively. The factored resistances of aluminum components and connections shall be determined in accordance with Section 17, except as specified in Clauses 12.5.5.2.2 and 12.5.5.2.3.



12.5.5.2.2 Heat treatment of aluminum The yield strengths of heat affected-zones for aluminum alloy 6063 sections up to 9.5 mm thick that are welded in the T4 temper with filler alloy 4043 and then artificially aged by precipitation heat treatment to the T6 temper after welding shall be taken as 85% of the yield strengths of the non-welded alloy 6063-T6. The yield strengths of heat-affected zones for aluminum alloy 6005 sections up to 6.4 mm thick that are welded in the T1 temper with filler alloy 4043 and then artificially aged by precipitation heat treatment to the T5 temper after welding shall be taken as 85% of the yield strengths of the non-welded alloy 6005-T5.

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The extent of heat-affected zones shall be determined in accordance with Clause 17.22.3.4. 

12.5.5.2.3 Aluminum castings The factored resistances of aluminum castings shall be based on the resistance factors for aluminum specified in Clause 17.5.7 and the aluminum alloy strengths specified in Table 12.9, or on strength testing of the castings. Factored resistances determined from tests shall have a 99% probability of exceedance (see CSA S6.1, Clause C17.5.7).



Table 12.9 Strengths for aluminum castings (See Clauses 12.5.5.2.3 and 17.4.1.)

Product and alloy

Strength, base metal, MPa

Strength, heat-affected zone, MPa

Fy

Fwy

60 80 70 90

50 50 50 50

60 60

50 50

Permanent mold castings A440.0-T4 356.0-T6 356.0-T7 A356.0-T61 Sand castings 356.0-T6 356.0-T7

12.5.5.2.4 Anchorages Highway accessory support anchorages shall satisfy the requirements of Clause 8.16.7 and shall fully develop the strength of the support. 

12.5.5.3 Serviceability limit states Highway accessory support components and connections shall be proportioned to satisfy the applicable serviceability limit state requirements of this Code. Support deformations shall be calculated for the load combination specified in Table A3.2.1 and shall be acceptable for the intended use of the support.

12.5.5.4 Fatigue limit state 

12.5.5.4.1 General Highway accessory support components and connections shall be proportioned so that their fatigue capacities are equal to or greater than the fatigue effects of the load combination specified in Table A3.2.1. Fatigue capacities shall be determined in accordance with Sections 8, 10, and 17, as applicable. Vortex shedding excitation arising from across-wind loads at the fatigue limit state shall be considered both with and without highway accessories installed. The use of damping or energy-absorbing devices shall be considered for highway accessory supports that are subject to significant vortex shedding excitation.

12.5.5.4.2 Anchor bolts In determining the stress range in an anchor bolt at the fatigue limit state, the effects of bending and of preloading of the bolt shall be considered. October 2011 (Replaces p. 565, November 2006)

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12.5.6 Breakaway supports 12.5.6.1 General Breakaway supports shall satisfy the requirements of Clause 12.5.5. In addition, they shall satisfy the crash test requirements of Clause 12.5.6 or have a satisfactory record of performing safely in actual service when struck by vehicles. Breakaway support crash test requirements shall be satisfied with highway shoulder and ditch geometry adjacent to the support that is similar to the geometry that will be adjacent to the support in service.

12.5.6.2 Crash test requirements Breakaway supports shall be crash tested in accordance with Tests 62 and 63 of NCHRP Report 230, except that the impact point for Test 63 may be the centre of bumper of the impacting vehicle. In addition, the maximum change in vehicle velocity during impact shall not exceed 5 m/s (a maximum of 3 m/s is preferred). All breakaway support columns in multiple-support roadside sign structures shall be considered as acting together to cause a change in vehicle velocity during crash testing unless (a) each support column is designed to release independently from the sign panel; (b) the sign panel has sufficient torsional strength to ensure this release; and (c) the clear distance between support columns is 2100 mm or greater.

12.5.6.3 Alternative crash test requirements A breakaway support may be assumed to have met the requirements of Clause 12.5.6.2 if it has been crash tested to requirements that test its breakaway behaviour to an equivalent or more severe level than the requirements of Clause 12.5.6.2. The crash test requirements for breakaway utility poles Test Level 3 of NCHRP Report 350 shall be taken as meeting the crash test requirements of Clause 12.5.6.2.

12.5.6.4 Changes to crash-tested highway accessory supports Changes to the details of the breakaway support columns of multiple-support roadside sign structures that meet the requirements of Clauses 12.5.6.2 and 12.5.6.3 may be made if all of the support columns within 2100 mm of each other have a total mass per unit length of less than 65 kg/m and a total mass of less than 270 kg between their breakaway bases and their release points from the sign panel.

12.5.6.5 Geometry No substantial remains of a breakaway support, after it is broken away, shall project more than 100 mm above ground level. The release point of a breakaway support column shall be at least 2100 mm above ground level.

12.5.7 Foundations 12.5.7.1 General Foundations for highway accessory supports shall comply with Section 6, except as specified in Clause 12.5.7.2. The foundation design shall be based on the lowest ground elevation expected to occur during the life of the support, including ground elevations occurring during construction.

12.5.7.2 Foundation investigation The foundation investigation for standard highway accessory support foundations that are designed for a wide range of soil conditions may be based on geotechnical information obtained from investigations at neighbouring sites, soil borings for highway design, or other appropriate sources provided that the soil conditions anticipated at the site fall within the range of soil conditions used to design the foundation.

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12.5.8 Corrosion protection 12.5.8.1 Steel Corrosion protection of steel components shall be provided in accordance with Section 10, except that (a) lapped joints of tubular steel supports shall be hot-dip galvanized; and (b) components of breakaway supports directly involved in the breakaway function, and components of anchorages cast into concrete foundations, shall be stainless steel or hot-dip galvanized steel. Stainless steel shall be ASTM A 167 Type 316 stainless steel. 

12.5.8.2 Aluminum

Corrosion protection of aluminum components shall be provided in accordance with Clauses 2.4  and 17.6.

12.5.8.3 Drainage and air circulation The top surface of a support foundation shall have a minimum wash slope of 2%, and with the exception of breakaway support foundations shall not be less than 75 mm above ground level. The ground adjacent to the support foundation shall be graded to prevent the ponding of water around the foundation. Support components shall be detailed to allow for inspection and maintenance, to prevent the accumulation of debris, and to allow for the free drainage of water and the free circulation of air both within and between components.

12.5.9 Minimum thicknesses 12.5.9.1 Steel The minimum thicknesses of steel members shall meet the requirements of Section 10, except that (a) the minimum thicknesses of steel truss members shall be 4.5 mm for chords and 3.0 mm for diagonals and bracing; and (b) the minimum thicknesses of steel pole supports of closed cross-section shall be 3.0 mm.

12.5.9.2 Aluminum The minimum thicknesses of aluminum truss members shall be 4.5 mm for chords and 3.0 mm for diagonals and bracing. The minimum thicknesses of aluminum pole supports of closed cross-section shall be 4.5 mm.

12.5.10 Camber Horizontal highway accessory support members shall be cambered to compensate for deflection due to unfactored dead loads. In addition, camber not less than L/1000 shall be provided for horizontal members of overhead and cantilevered supports.

12.5.11 Connections 12.5.11.1 Bolts Bolts for structural connections in aluminum members shall be stainless steel or hot-dip galvanized steel.

12.5.11.2 Circumferential welds Circumferential welds in pole-support members shall be complete penetration welds, except that the connections of steel pole-support members to base plates for luminaire and traffic signal supports not greater than 16 m in height may be socket-type connections with a continuous fillet weld on the inside of the base plate at the end of the shaft and another continuous fillet weld on the outside at the top of the base plate.

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12.5.11.3 Longitudinal welds Longitudinal seam welds in steel pole-support members within 150 mm of a complete penetration circumferential weld or within 150 mm of a lapped joint shall be complete penetration welds ground flush after welding.

12.5.11.4 Lapped joints Lapped joints in tubular members shall be of sufficient length to develop the full strength of the lapped members. The ends of the plates in the joint shall not be chamfered over more than 50% of their thickness.

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Section 13 — Movable bridges 13.1 13.2 13.3 13.4 13.4.1 13.4.2 13.4.3 13.4.4 13.4.5 13.4.6 13.4.7 13.4.8 13.4.9 13.4.10 13.5 13.5.1 13.5.2 13.5.3 13.5.4 13.5.5 13.5.6 13.5.7 13.5.8 13.5.9 13.5.10 13.5.11 13.5.12 13.5.13 13.6 13.6.1 13.6.2 13.6.3 13.6.4 13.6.5 13.7 13.7.1 13.7.2 13.7.3 13.7.4 13.7.5 13.7.6 13.7.7 13.7.8 13.7.9 13.7.10 13.7.11 13.7.12 13.7.13 13.7.14 13.7.15 13.7.16

Scope 572 Definitions 572 Symbols 572 Materials 573 General 573 Structural steel 573 Concrete 573 Timber 574 Carbon steel 574 Forged steel 574 Cast steel or iron 574 Bronze 574 Bolts 574 Wire rope 574 General design requirements 574 General 574 Type of deck 574 Piers and abutments 574 Navigation requirements 574 Vessel collision 574 Protection of traffic 575 Fire protection 575 Time of operation 575 Aligning and locking 575 Houses for machinery, electrical equipment, and operators 575 New devices 575 Access for routine maintenance 575 Durability 576 Movable bridge components 576 General features 576 Swing bridge components 580 Bascule bridge components 583 Rolling lift bridge components 583 Vertical lift bridge components 584 Structural analysis and design 589 General 589 Design theory and assumptions 589 Wind loads 589 Seismic loads 590 Reaction due to temperature differential 590 Hydraulic cylinder connections 591 Loads on end floor beams and stringer brackets 591 Swing bridges — Ultimate limit states 591 Bascule (including rolling lift) bridges — Ultimate limit states 592 Vertical lift bridges — Ultimate limit states 593 Dead load factor 593 All movable bridges — Ultimate limit states 594 Special types of movable bridges 594 Load effects 594 Fatigue limit state 594 Friction 594

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13.7.17 13.7.18 13.7.19 13.8 13.8.1 13.8.2 13.8.3 13.8.4 13.8.5 13.8.6 13.8.7 13.8.8 13.8.9 13.8.10 13.8.11 13.8.12 13.8.13 13.8.14 13.8.15 13.8.16 13.8.17 13.8.18 13.8.19 13.8.20 13.9 13.10 13.10.1 13.10.2 13.10.3 13.10.4 13.10.5 13.10.6 13.10.7 13.10.8 13.10.9 13.10.10 13.10.11 13.10.12 13.10.13 13.10.14 13.10.15 13.10.16 13.10.17 13.10.18 13.10.19 13.10.20 13.10.21 13.10.22 13.10.23 13.10.24 13.10.25 13.10.26 13.10.27 13.10.28

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Machinery supports 594 Vertical lift bridge towers 594 Transitory loads 594 Mechanical system design 594 General 594 Operating machinery 595 Power sources 595 Prime mover 595 Power requirements for main machinery 596 Wedges 596 Brakes 597 Frictional resistance 598 Torque 599 Application of worker power 601 Machinery loads 601 Allowable stresses for machinery and allowable hydraulic pressures 601 Bearing pressures (moving surfaces) 603 Line-bearing pressure 605 Design of wire ropes 605 Shafting 607 Machinery fabrication and installation 608 Lubrication 614 Power equipment 615 Quality of work 617 Hydraulic system design 618 Electrical system design 619 General 619 Canadian Electrical Code, Part I 619 General requirements for electrical installation 619 Working drawings 620 Motor and generator tests 620 Motors — General requirements 621 Motor torque for span operation 621 Motor temperature, insulation, and service factor 622 Number of motors 622 Synchronizing motors for tower-drive vertical lift bridges 622 Speed of motors 622 Gear motors 622 Engine-generator sets 622 Automatic electric power transfer 623 Electrically operated motor brakes 624 Electrically operated machinery brakes 625 Design of electrical parts 625 Electrical control 625 Speed control for span-driving motors 627 Master switches and relays for span-driving motors 628 Programmable logic controllers 628 Resistances and reactors 628 Limit switches 629 Interlocking 629 Switches 629 Circuit breakers and fuses 630 Contact areas 630 Magnetic contactors 630

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13.10.29 13.10.30 13.10.31 13.10.32 13.10.33 13.10.34 13.10.35 13.10.36 13.10.37 13.10.38 13.10.39 13.10.40 13.10.41 13.10.42 13.10.43 13.10.44 13.10.45 13.10.46 13.10.47 13.10.48 13.10.49 13.10.50 13.11 13.11.1 13.11.2 13.11.3 13.12 13.13 13.14

Canadian Highway Bridge Design Code

Overload relays 630 Shunt coils 630 Instruments 630 Protection of electrical equipment 631 Cast iron in electrical parts 631 Position indicators and meters 631 Indicating lights 631 Control console 631 Control panels 632 Enclosures for panel boards 632 Electrical wires and cables 632 Tagging of wires 633 Wire splices and connections 633 Raceways, metal conduits, conduit fittings, and boxes 633 Electrical connections between fixed and moving parts 634 Electrical connections across the navigable channel 635 Service lights 635 Navigation lights 636 Aircraft warning lights 636 Circuits 636 Grounding and lightning protection 636 Spare parts 636 Construction 637 Shop assemblies 637 Coating 637 Erection 637 Training and start-up assistance 639 Operating and maintenance manual 639 Inspection 640

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Section 13 Movable bridges 13.1 Scope This Section specifies requirements for the design, inspection, maintenance, construction, and rehabilitation of conventional movable highway bridges, i.e., bascule (including rolling lift), swing, and vertical lift bridges, and deals primarily with the components involved in the operation of such bridges.

13.2 Definitions The following definitions apply in this Section: Bascule bridge — a movable bridge that rotates about a horizontal axis. Bridge closed or in closed position or in seated position or in fixed position — the bridge is in a position that permits highway traffic to use it. Bridge open or in open position — the bridge is in a position that allows navigation to proceed. Operating mode — any position during opening or closing when neither navigation nor highway traffic can proceed. Operator — a person or persons who control a movable bridge system. Primary power — the power required to operate a prime mover (electric power in the case of electric motors). Prime mover — the normal means provided for driving machinery, e.g., human effort, compressed air, hydraulics, an electric motor, or an internal combustion engine. Rolling lift bridge — a type of bascule bridge that rotates in the vertical plane and translates horizontally at the same time. Swing bridge — a movable bridge that rotates about a vertical axis. Vertical lift bridge — a movable bridge that raises and lowers vertically, guided by a tower or other means at each end.

13.3 Symbols The following symbols apply in this Section: B

= angle of helical strand with axis of rope, radians (degrees)

D

= rolling diameter of segment, mm (in); pitch diameter of sheave or drum, mm (in)

Do

= dead load (bridge open in any position or closed with ends just touching), kN (lb)

Dt

= dead load (bridge closed; counterweight supported for repairs), kN (lb)

d

= diameter of journal or step bearing, mm (in); mean diameter of collar or screw, mm (in); diameter of roller or rocker, mm (in); diameter of segmental girder, mm (in); diameter of shaft, mm (in)

dr

= rope diameter, mm (in)

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dw

= diameter of largest individual wire, mm (in)

E

= modulus of elasticity of wire, taken as 197 000 MPa (28 500 000 psi)

f

= extreme fibre stress, MPa (psi)

Ho

= horizontal force, taken as 5% of the total moving load carried by the steel towers and/or special parts of the structure that support the counterweight assembly, with the bridge open in any position, kN (lb)

I

= initial tension in a rope, kN (lb)

Io

= operating impact, taken as 20%

K

= impact actor f

L

= angle of helical wire with axis of strand, radians (degrees); length of shaft between bearings, mm (in)

Lc

= live load (including dynamic load allowance), with the bridge closed and the ends just touching, and the bridge considered as a continuous structure (reactions at both ends to be positive), kN (lb)

Ls

= live load (including dynamic load allowance) on one arm as a simple span, with the bridge closed and the ends just touching, kN (lb)

Lt

= live load (including dynamic load allowance), with the bridge closed and the counterweight supported for repairs, kN (lb)

M

= actual bending moment, N•mm (ft•lb)

Mo

= maximum forces on structural parts caused by the operation of machinery, increased 100% for impact, N•mm (ft•lb)

N

= number of threads of lead of worm

n

= revolutions per minute; revolutions per minute of rotating part

P

= minimum tension in the slack rope, kN (lb)

p

= circular pitch of teeth on wheel; the least of the values of the yield strength of the material in the roller, rocker, roller bed, or track, MPa (psi); the lesser of the values of the yield strength of the steel in the segmental girder tread or track, MPa (psi)

R

= radius of worm, mm (in)

r

= radius of roller, mm (in); radius of gyration, mm (in)

T

= twisting moment or torque, N•mm (ft•lb)

Ti

= maximum operating tension in a rope (including unbalance, if any), kN (lb)

Wo

= wind load, with the bridge open in any position or closed with the ends just touching, kN (lb)

αD

= dead load factor (see Table 13.6)

13.4 Materials 13.4.1 General The material and product standards for machinery shall comply with the applicable requirements of Clause 13.8 or be subject to Approval.

13.4.2 Structural steel Structural steel materials and products shall be in accordance with Clause 10.4.

13.4.3 Concrete Concrete materials and products shall be in accordance with Clause 8.4.

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13.4.4 Timber Timber materials and fasteners shall be in accordance with Section 9.

13.4.5 Carbon steel Hot-rolled carbon steel bars shall comply with ASTM A 675/A 675M.

13.4.6 Forged steel Forged carbon steel and forged alloy steel shall comply with ASTM A 668/A 668M.

13.4.7 Cast steel or iron Cast steel shall comply with ASTM A 27/A 27M and ASTM A 148/A 148M. Cast iron shall comply with ASTM A 48/A 48M.

13.4.8 Bronze Bronze shall comply with ASTM B 22.

13.4.9 Bolts Carbon steel bolts and studs shall comply with ASTM A 307 or ASTM F 568M. Quenched and tempered steel bolts and studs shall comply with ASTM A 449. High-strength structural bolts shall comply with ASTM A 325/A 325M or ASTM A 490/A 490M.

13.4.10 Wire rope Wire rope shall comply with CSA G4, subject to the other requirements of this Section.

13.5 General design requirements 13.5.1 General Any movable bridge in a closed position shall be designed as a fixed bridge in accordance with this Section and other applicable Sections of this Code.

13.5.2 Type of deck Consideration shall be given to the use of a solid deck of lightweight construction to improve rideability, reduce noise, and protect the systems under the deck.

13.5.3 Piers and abutments The drawings shall contain information on the magnitude, direction, and points of application of all loads and forces that components of the movable bridge could exert on the piers and abutments for all load combinations.

13.5.4 Navigation requirements The location of the movable span relative to the waterway and the vertical and horizontal clearances for the bridge, in both the open and closed positions, shall meet the requirements of the Navigable Waters Protection Act. The type, quantity, and location of lights, signs, and beacons for navigation and aircraft protection shall meet the requirements of Transport Canada and any other authority having jurisdiction.

13.5.5 Vessel collision The vessel collision requirements of Section 3 shall apply to movable bridges. Any part of a superstructure that is exposed to vessel collision in the open position shall also be protected.

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13.5.6 Protection of traffic Traffic warning signs, lights, bells, or gates, or other safety devices, shall be provided for the protection of pedestrian and vehicular traffic. They shall be designed to be operative prior to the opening of the movable span and remain operative until the span has been completely closed. They shall also comply with the requirements of the Transportation Association of Canada’s Manual of Uniform Traffic Control Devices for Canada. Where, after a bridge is closed to vehicular traffic, a vehicle continuing in its path could fall into the waterway, the use of movable barriers shall be considered.

13.5.7 Fire protection Provision shall be made for effective smoke and fire detection and for the protection of those components of movable bridges that contain combustible material, e.g., timber decks and operator’s houses, in accordance with the requirements of the National Building Code of Canada and the National Fire Code of Canada.

13.5.8 Time of operation Under normal operation, the operating machinery shall drive the span from the seated to the fully open position, or vice versa, in not more than about 2 min.

13.5.9 Aligning and locking Movable bridges shall be equipped with suitable mechanisms to level and align the fixed and movable roadway elements and to fasten the movable span securely in position so that it cannot be displaced either horizontally or vertically under all loading conditions. Effective end-lifting devices shall be used for swing bridges and span locks shall be used for bascule bridges. Span locks shall also be provided for vertical lift bridges when specified by the Owner. Span locks on movable bridges shall be designed so that they cannot be driven unless the movable parts are within 15 mm of their proper positions.

13.5.10 Houses for machinery, electrical equipment, and operators A suitable house or houses shall be provided for the machinery, electrical equipment, and operator. Houses shall be large enough to permit easy access to all equipment. They shall be fireproof, weatherproof, and climate controlled and shall comply with the requirements of the National Building Code of Canada, Class D or F (as determined by the authority having jurisdiction), as well as with all applicable health and safety regulations. The operator’s house shall be located so as to afford a clear view of vehicular, pedestrian, and water-borne traffic.

13.5.11 New devices The use of state-of-the-art or recently developed mechanical or electrical devices, materials, or techniques that might be suitable for use in movable bridges and are not covered in this Section may be considered. If any such devices, materials, or techniques are used, they shall be in accordance with good commercial practice, have a history of successful application for similar uses, and be subject to the approval of the Engineer.

13.5.12 Access for routine maintenance Non-combustible stairways, platforms, and walkways protected by metal railings shall be provided to give safe access to the operator’s house, machinery, trunnions, counterweights, lights, bridge seats, and all other points requiring maintenance, inspection, and servicing. Ladders may be installed only where stairways are not feasible and shall be provided with safety devices when required by applicable codes. In vertical lift bridges, ladders and walkways shall be installed to give access to the moving span in any position from either tower. The requirements of the authority having jurisdiction shall also apply. Machinery platforms and access walkways shall be strong enough to support components of machinery parts during dismantling for minor repairs or inspection, in addition to the mass of the workers.

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In tower-drive vertical lift bridges, an electrically driven elevator should be provided in each tower unless the lift is short. Machinery assemblies shall be designed so that all parts that can require maintenance, adjustment, or replacement are readily accessible. Ample clearance shall be provided for easy removal or replacement of such parts.

13.5.13 Durability The durability requirements for structural materials and details shall be in accordance with Section 2. Durability of the operational aspects of the structure shall be achieved through conservative design, proper allowance for wear, adjustment in alignment, and ease of replacement. For mechanical, electrical, and hydraulic systems, design for durability shall take into account the operational environment, frequency of operation, and need for reliability. A manual shall be prepared specifying proper maintenance and inspection procedures.

13.6 Movable bridge components 13.6.1 General features 13.6.1.1 Counterweights 13.6.1.1.1 General The counterweights for bascule, vertical lift, and rolling lift bridges shall be designed to balance the moving span and all of its attached parts in any operating position, except that there shall be a small positive reaction on the span shoes when the span is closed. Counterweights for swing spans shall be used to counteract unsymmetrical dead loads on the span.

13.6.1.1.2 Centres of gravity Final calculations for the total mass of the moving span, including all attached parts, and the counterweight, including its supporting framework or box, shall be based on the mass calculated from the shop drawings. Final calculations for the positions of the centre of gravity of the moving span and counterweight shall also be based on this calculation of mass. The total mass and location of the centre of gravity of the moving span and of the counterweight shall be separately shown on the assembly drawings or erection drawings. All final calculations shall be submitted to the Engineer.

13.6.1.1.3 Unsymmetrical counterweights When a movable bridge is unsymmetrical in transverse section, the counterweight shall be designed so that its centre of gravity will lie in the same vertical plane as that of the moving span.

13.6.1.1.4 Design Counterweights should be supported by an embedded structural steel frame designed to carry the full mass of the counterweight. Alternatively, a counterweight may consist of a structural steel plate box suitably braced and filled with concrete. Care shall be taken to prevent corrosion of the structural steel at all points where the structural steel enters or is adjacent to the concrete. Structural steel entering concrete shall be protected 300 mm into the concrete and be sealed at the steel/concrete interface. Reinforcing bars shall be designed to provide for all conditions of internal stresses, with the counterweight in any position, and to distribute adequately the mass of concrete to the panel points of the supporting steel or to the connections between the counterweight and the bridge members.

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13.6.1.1.5 Connections The connections between the counterweight and its supporting bridge members shall be designed for fatigue. For design purposes, the bond between the concrete of the counterweight and the surfaces of the structural steel shapes or plates of the support frames or bridge members shall be ignored.

13.6.1.1.6 Contact surfaces All surfaces of structural steel that come into contact with the counterweight concrete shall remain uncoated, except as specified in Clause 13.6.1.1.4.

13.6.1.1.7 Concrete Counterweights shall be of non-air-entrained concrete and designed in accordance with Section 8. The concrete strength shall be 30 MPa (minimum) at 28 days unless otherwise specified. For design purposes, concrete for counterweights shall be assumed to have a density of 2355 kg/m3 unless special aggregates are specified and used. At the start of a contract, the contractor shall determine the mass of the concrete experimentally, using aggregates typical of those to be used at the time the counterweight is to be constructed. At least three samples made from separate batches, each with a volume of at least 0.1 m3, shall be used for mass determinations. The test samples shall be moist cured for 28 days and air cured thereafter. The mass shall be determined at 28 days and thereafter at regular intervals until the mass is stabilized. The design of the counterweight shall be modified if the experimental density differs from the density used in the design. Concrete in counterweights that rotate about a horizontal axis during the operation of the moving span shall be placed in one continuous pour whenever practicable.

13.6.1.1.8 Counterweight adjustment Counterweights shall be arranged so that adjustments in mass can be made to allow for variation in the mass of the moving span and to provide for minor discrepancies between the calculated and actual mass of the moving span and counterweight. Adjustments in mass shall normally be made by adding or removing concrete balance blocks. In special cases, cast iron balance blocks may be used. Balance blocks shall be of a size that can be lifted by one person (in accordance with applicable labour codes) and shall have lifting handles or lifting lugs. For design purposes, it shall be assumed, in order to establish the dimensions of the fixed portion of each counterweight, that 3.5% of each counterweight will be in the form of balance blocks. The total mass of balance blocks to be supplied by the contractor shall be equal to that required to balance the span plus spare blocks equal to 0.5% of the mass of the counterweight.

13.6.1.1.9 Pockets The balance blocks shall preferably be placed in pockets or galleries in the counterweight and means shall be provided, where necessary, to hold them in position. The centre of gravity shall not be displaced. Space for balance blocks shall be provided in each counterweight so that adjustments in mass amounting to 3.5% under and 5.0% over the calculated mass of the counterweight can be effected.

13.6.1.1.10 Drain holes Pockets shall be provided with drainage holes that have a minimum diameter of 40 mm.

13.6.1.1.11 Covers Removable but secured weather protection covers shall be provided for the balance block pockets.

13.6.1.1.12 Unequal arm swing bridges Counterweights shall be used to balance unequal arm swing bridges about the centre of rotation.

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13.6.1.1.13 Vertical lift bridge overtravel Counterweights for vertical lift bridges shall clear the fixed structure by at least 1 m when the span is raised to its open position. In determining this clearance, the stretch in the counterweight ropes due to initial loading plus any lengthening during service shall be assumed to be 1.0% of the calculated length of the rope.

13.6.1.1.14 Counterweight temporary support For vertical lift bridges, provision shall be made for the independent support of counterweights during construction and for rope replacements.

13.6.1.2 Buffers Movable bridges may be equipped with buffers or hydraulic shock absorbers designed to absorb energy when the span is being seated.

13.6.1.3 Bridge stops Bridge stops shall be provided in order to limit the travel of the moving span in the open position. They may be made of wood or another material suitable for cushioning or may take the form of buffers.

13.6.1.4 Span aligning and locking To prevent both horizontal and vertical displacement under the action of traffic, wind, or any other cause of displacement, moving spans shall have centring and seating devices that accurately align and securely lock the spans into position. For swing bridges, the aligning mechanism may be an automatically closing latch or other suitable aligning and locking device operated by the end-lift mechanism, or the end-lifts may themselves be designed to align the bridge. Locks at the junction of double-leaf bascule bridges shall be designed to transmit live load shear when there is live load on one leaf only. Where the ends of bascule bridge decks are located behind the centre of rotation and calculations indicate that the toe could be lifted from the toe rest under the passage of live load, tail locks shall be provided in order to resist the maximum reactions from live load.

13.6.1.5 Equalizing devices For power-operated swing bridges with two or more main pinions, the shafts of the pinions shall be connected by a device that will equalize the turning forces at the pinions. For power-operated bascule and rolling lift bridges in which two or more racks per leaf are used, a device shall be provided to equalize the load on the main pinions. Separate drives for each main pinion, with common control to provide equalization, may be used in lieu of mechanical equalization. On span-drive vertical lift bridges, take-ups shall be provided at the anchored end of each operating rope for adjusting and equalizing the loads in them. These take-ups shall be self-locking and accessible for maintenance and inspection. On tower-drive vertical lift bridges, warping devices shall be provided to level the span in the transverse direction.

13.6.1.6 Traffic signals Traffic lights should be installed at least 25 m from each end of the moving part of the structure. When required by safety regulations, or if specified by the Owner, a sound-producing device shall be installed at the bridge to warn that the bridge is about to open. The sound shall be clearly audible at a distance of 450 m in still air.

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13.6.1.7 Traffic warning gates Traffic warning gates shall be provided for movable bridges in order to prevent pedestrians and vehicular traffic from getting onto the movable span during the operating cycle. These warning gates shall be power operated and controlled from the operator’s house unless otherwise specified by the authority having jurisdiction. Provision shall be made for hand operation in case of power failure. The warning gates should not be closer than 15 m from the ends of the movable span. They shall be painted so as to attract attention and be readily visible both day and night. They shall have red lights, reflectors, and, if required by the Owner, danger or stop signs. Electric bells controlled from the operator’s house shall be provided to warn that the gates are about to close. Warning gates and safety equipment should be units of standard commercial manufacture for which replacements and spare parts are readily obtainable. The use of custom-built units shall be avoided as far as possible.

13.6.1.8 Movable barriers Consideration shall be given to including energy-absorbing movable barriers in addition to warning gates for vertical lift and swing bridges and for the toe ends of single-leaf bascule or rolling lift bridges. When movable barriers are specified, they shall be installed in the area between the warning gates and the movable span. The minimum distance from the ends of the movable span to the movable barriers shall be determined by the anticipated deflection of the barriers under traffic impact.

13.6.1.9 Interlocking The bridge-operating machinery shall be interlocked in such a manner that it can operate only in a predetermined and specified sequence for both opening and closing the bridge. The controls for the operating machinery shall be interlocked with locks and/or wedges and with traffic signals, traffic gates, and/or traffic barriers in such a manner that the machinery for opening the bridge cannot be started until the locks and/or wedges are drawn and the traffic signals, gates, and/or barriers are set at the stop position. Similarly, it shall be impossible for signals, gates, and/or barriers to be set at the go position until all of the operations for closing the bridge have been performed. Lockable bypass switches may be added to allow manual operation of individual devices and the span drive in the event of failure of any device or any part of the interlocking controls.

13.6.1.10 Position indicator An indicator that shows the position of the moving span at all times shall be installed on the control desk and adjacent to any emergency span-operating station.

13.6.1.11 Houses for machinery, electrical equipment, and operator Suitable houses or housings shall be provided for the protection of the machinery, electrical equipment, and operator. They shall be weatherproof, of fireproof construction, and equipped with fire extinguishers. Houses shall be large enough for easy access to equipment. Where practicable, a hand-operated chain block and trolley-beam system shall be provided in order to facilitate the replacement of motors and other machinery parts. In houses in which control or other electrical equipment is installed, adequate means of temperature control shall be provided. An opening or openings in the form of doors, removable windows, or panels that are large enough to accommodate the largest piece of equipment shall be provided. Floors shall have non-skid surfaces. Control desks and electrical equipment may be located in the machinery enclosure or in a separate room or house. The location and construction of the operator’s house shall be such that the operator has an adequate view of all vehicular, pedestrian, and water-borne traffic.

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The operator’s house shall be adequately insulated and climate controlled during the operating season in accordance with health and safety regulations and to suit local climatic conditions. Sanitary conveniences shall be provided for the use of the operator. Adequate facilities shall be provided for routine maintenance and emergency repairs.

13.6.1.12 Provision for jacking For swing bridges, provision shall be made for jacking needed in the repair or replacement of components such as the centre pivot, circular roller track assembly, and wedges. For bascule bridges, provision shall be made for the inspection, repair, or replacement of all main trunnions and trunnion bearings, unless otherwise directed by the Owner. The structure shall be designed to withstand the reactions from the jacks.

13.6.2 Swing bridge components 13.6.2.1 Centre bearing 13.6.2.1.1 Arrangement at centre Centre-bearing swing bridges shall be designed so that, when the bridge is rotating, the entire mass of the moving span will be carried on a centre pivot. When the bridge is closed, the girders or trusses should be supported for live load at their centres on wedges.

13.6.2.1.2 Bearings Centre-bearing bridges shall rotate on spherical disc thrust bearings. Disc bearings shall consist of a bronze disc and a hardened steel disc designed so that sliding will occur entirely between the bronze and hardened steel surfaces. The discs shall be turned, accurately ground to a highly polished finish, and positively locked against rotation. Straight oil grooves shall be cut into the bronze discs as necessary for proper lubrication. The span shall be effectively held laterally to resist the specified wind force on the bridge while swinging, and provision shall be made for removal of the bearings without jacking up the structure more than is necessary to take the load off the centre pivot, and without interfering with the operation of traffic over the bridge.

13.6.2.1.3 Pivot support The centre pedestal supporting the pivot shall be made of cast or welded steel. It shall be proportioned for both strength and rigidity and shall be securely anchored to the support.

13.6.2.1.4 Balance wheels No fewer than eight wheels running on a circular track shall be provided to limit the tilting of the bridge and transmit wind loads and any other unbalanced effects to the track while the bridge is rotating. Balance wheels shall be adjustable for height and shall be machined conical or crowned on treads except where rails are used for the track.

13.6.2.1.5 Hub length Where the axles for balance wheels are fixed and the whole wheel bearing rotates about the axle, the wheel hub shall be of such a length that any line normal to the wheel tread shall lie well within the outside edge of the wheel bearing.

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13.6.2.2 Rim bearing 13.6.2.2.1 Arrangement at centre Rim-bearing swing bridges shall be designed so that most or all of the mass of the moving span is carried on a circular conical roller track assembly when the bridge is rotating. The roller assembly shall be proportioned for the combined effect of the specified dead load and wind load when the bridge is rotating, and for the combined dead load, live load (including dynamic effects), and wind load when the bridge is closed.

13.6.2.2.2 Load distribution The load on the rim girder of a rim-bearing or combined rim and centre-bearing swing bridge shall, if practicable, be distributed equally among the bearing points. The bearing points shall as nearly as is practicable be spaced equally around the rim girder.

13.6.2.2.3 Struts Rigid struts shall connect the rim girder to a centre pivot firmly anchored to the pier. A strut shall be attached to the rim girder at each bearing point and at intermediate points if necessary.

13.6.2.2.4 Rim girders Rim girders and upper treads shall be designed so that the load will be properly distributed over the rollers. For calculating stresses in the girder, the load shall be assumed to be distributed equally among all rollers. The span lengths shall be taken as the developed length of the girder between adjacent bearing points and analyzed as a continuous girder.

13.6.2.2.5 Rollers Rollers shall be machined conical on the treads. Rollers shall be adjustable axially to provide equal load sharing among all rollers.

13.6.2.3 Main pinions 13.6.2.3.1 General At least two main pinions shall be used. Where two pinions are used, they shall be placed diametrically opposite one another. Where four pinions are used, they shall be placed in two diametrically opposite pairs.

13.6.2.3.2 Pinion-bearing supports The brackets and connections that support the main pinion bearings shall be designed for at least twice the maximum design torque in the pinion.

13.6.2.3.3 Pinion bearings Pinion-bearing housings and bearing caps shall be secured with turned bolts. The bearings shall be designed with enough shims to provide for overrun or under run in the diameter of the rack.

13.6.2.4 Racks Rack segments should be made from cast steel. Racks should be bolted to the supporting steelwork to facilitate adjustment and replacement. They shall be machined at connections to supports and at their joints. Where racks are mounted on tracks, the joints shall be staggered. Separate rack and track segments should be used. Racks mounted on the substructure that are not attached to the track shall be anchored to the foundation by an ample number of anchor bolts; the tractive force developed when turning the bridge

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shall be taken by at least one lug on each rack segment, extended from the bottom of the rack downward into the support and set in cement mortar, concrete, or grout.

13.6.2.5 Track and treads The lower treads of rim-bearing swing bridges and the tracks for centre-bearing swing bridges shall be made sufficiently strong and stiff to properly distribute the maximum roller or balance-wheel load to the substructure. The rolling surfaces of treads and tracks shall be machined conical to provide pure rolling motion with the rollers as the bridge rotates. The track segments shall be made of cast steel or steel weldments. For small spans, where balance wheel loads are light, steel rails may be used for track. These rails shall be connected to structural steel plates to secure adequate anchorage. The treads attached to rim girders shall be rolled steel slabs or steel castings and shall not be considered part of the girder flange material. The treads shall be considered pedestals that distribute the line-bearing pressures from the roller to the girders. That part of the outstanding leg of a girder flange angle that is beyond the outside face of the vertical leg shall not be considered the bearing area. The surface of the bottom flange of rim girders that bears on the tread shall be machined. The centreline shall be inscribed on the surface of the treads.

13.6.2.6 End-lifts 13.6.2.6.1 Type The end-lift mechanism to be used shall be simple and positive in action. The actuating mechanism shall be non-reversible under the action of the live load.

13.6.2.6.2 Capacity The end-lifting machinery shall be designed to exert an upward force equal to at least 1.5 times the maximum negative end reaction of the live load (including dynamic load allowance) plus the reaction caused by the deflection due to temperature differential.

13.6.2.6.3 Height of lift The end-lifting machinery shall be proportioned to lift the ends of the span an amount that will ensure a positive reaction under all conditions of live load and to remove deflection due to temperature differential. The vertical height of lift shall be the sum of the following: (a) the deflection due to 1.5 times the maximum live load negative reaction; (b) the deflection due to the temperature differential between the top and bottom chords; (c) the height to which the end of the bridge can tilt until limited by the balance wheels; (d) adequate clearance for swinging; and (e) additional temperature deformations in the longitudinal and transverse directions (in the case of solid decks).

13.6.2.7 Wedges Wedges shall be designed so that they cannot be displaced by action of the moving load or by power failure. They shall be capable of adjustment. The centre wedges and supports shall be proportioned for the reaction from live load (including dynamic effects) and shall have suitable means to achieve an equal bearing without the span being lifted. End wedges shall be proportioned to provide the required vertical height of lift and to support all forces from the wedging action and applied loads.

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13.6.3 Bascule bridge components 13.6.3.1 Centring devices Transverse centring of the toe ends of single- and double-leaf bascule spans shall be provided by devices located on or near the centreline of the bridge. The lateral clearance in the centring device shall not exceed 2 mm.

13.6.3.2 Locking devices Single-leaf bascule spans shall have, at a minimum, a locking device at the toe end of each outside girder or truss to hold the leaf down against its seat. Double-leaf bascule spans shall have, at a minimum, shear locks at the toe ends of each outside pair of girders or trusses to align the leaves vertically and maintain alignment with live load on one leaf only. Tail locks shall be provided when the deck of the bascule leaves extends behind the centreline of trunnions to resist the maximum reaction from live loads.

13.6.3.3 Trunnions and trunnion hubs Trunnions for bascule spans shall be steel forgings and shall be interference fitted into cast steel hubs. Hubs and trunnions shall be tightly dowelled or keyed against rotation. Trunnion hubs shall be interference fitted into bascule spans and shall also be secured by a sufficient number of bolts to transmit the entire applied load and frictional torque. The design of the trunnion shall minimize stress concentrations.

13.6.4 Rolling lift bridge components 13.6.4.1 Segmental and track girders 13.6.4.1.1 General The flanges of segmental and track girders for rolling lift bridges shall be symmetrical about their web or webs. The width of contact between the web of the segmental girder and the back of the tread plate shall be equal to the corresponding width of contact in the track girder.

13.6.4.1.2 Machining The face of the flange shall be machined for full bearing on the tread or track plate.

13.6.4.1.3 Design The unit-bearing pressure of the web plate on the tread shall not exceed one-half of the yield stress of the material in tension. In calculating the unit-bearing pressure, the force shall be considered as distributed over a rectangular area whose width is the thickness of the web and whose length is 1.6 times the least thickness of the tread.

13.6.4.2 Treads and track The treads attached to the segmental girders and the track girders shall be rolled steel plates, forgings, or castings. They shall not be considered part of the girder flange material. The thickness of treads shall be at least 75 mm plus 0.004D, where D is the rolling diameter of the segment in millimetres. The top and bottom surfaces of the treads and track shall be machined. Their ends shall be machined to bear and they shall be designed to be replaceable. The treads and track shall be continuous (without any joint) if practicable. They shall be connected to the segmental and track girders so that, as far as possible, they act monolithically with them to prevent any working at the contact surfaces. Where treads and tracks are made in segments, the number of joints shall be kept to a minimum. The faces of the joints between the segments shall be in planes at right angles to the rolling surface and the girders shall be fully stiffened at these joints. November 2006

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13.6.5 Vertical lift bridge components 13.6.5.1 Auxiliary counterweights Auxiliary counterweights shall be used to balance the mass of the main counterweight ropes as the lift span opens and closes. Any unbalanced rope mass not compensated by auxiliary counterweights shall be included in the lift span power calculations.

13.6.5.2 Span guides 13.6.5.2.1 Lower guides The span guides for all vertical lift bridges shall be attached at the level of the bottom lateral bracing system. At one end of the moving span, the two guides shall control the movement of the span in the longitudinal and transverse directions. At the other end, the two guides shall control the movement of the span in the transverse direction only.

13.6.5.2.2 Upper guides For through-truss bridges, two upper guides shall be provided at each end of the moving span at the level of the top chord lateral system. They shall control the movement of the span in the transverse direction only.

13.6.5.2.3 Clearances The normal running clearance between the mating surfaces of the span guides and the tower guide track shall be 15 mm in the transverse and longitudinal directions. All span guides shall be adjustable to allow for accurate alignment between the lift span and tower structures.

13.6.5.2.4 Guide material Span guides shall be made of steel plate, steel weldments, or steel castings. Sliding guides shall be fitted with bronze liners arranged for easy replacement when necessary. Guide rollers shall be made of steel.

13.6.5.2.5 Tower guide track The tower guide track shall be designed to transfer the loads from the span guides to the tower structure. All guide track running surfaces shall be machined. The tower guide track may be flared at the bottom to reduce the normal running clearances of the lower guides from 15 to 3 mm as the lift span approaches its closed position, thereby centring the span before it seats. Alternatively, centring devices may be incorporated into end floor beams.

13.6.5.3 Counterweight guides 13.6.5.3.1 Guide shoes A minimum of four guide shoes shall be provided for each counterweight, two on each side, spaced as far apart as practicable in the vertical direction.

13.6.5.3.2 Clearances The normal running clearance between the mating surfaces of the counterweight guide shoes and the guide track shall be 20 mm in the transverse direction and 15 mm in the longitudinal direction. All counterweight guide shoes shall be mounted on shims for transverse and longitudinal adjustments.

13.6.5.3.3 Shoe material Counterweight guide shoes shall be made of steel weldments, steel castings, or bronze castings and shall be adjustable and replaceable. Steel shoes shall be fitted with bronze liners arranged for easy replacement.

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13.6.5.3.4 Counterweight guide track The running surfaces of counterweight guide track that are subject to transverse loads shall be machined. Joints shall be machined and provision shall be made for lateral adjustment.

13.6.5.4 Counterweight sheaves 13.6.5.4.1 General Counterweight sheaves shall be cast or welded and shall have interference fits on the trunnion shafts. Hubs shall be secured to trunnion shafts with driving-fit dowels set in holes drilled after the sheave is shrunk onto the trunnion shaft. Rope grooves shall be machined to suit the diameter of the rope. The space between ropes shall be at least 6 mm. All of the grooves of all of the sheaves shall have a uniform pitch diameter and the variation from the specified diameter shall not exceed ± 0.25 mm.

13.6.5.4.2 Welded counterweight sheaves Counterweight sheaves fabricated by welding shall have structural steel plate rims and webs and forged carbon steel hubs with controlled chemical content to ensure weldability. Welded sheaves shall be stress relieved prior to machining. Details shall be suitable for the anticipated load cycles on the sheaves. The allowable stress ranges specified in Clause 10.17 shall be used for design. A dynamic load allowance of at least 20% shall be included in the design loading.

13.6.5.4.3 Operating rope drums and deflector sheaves Rope grooves shall be machined to suit the diameter of the rope. The clear space between ropes shall be at least 3 mm. Deflector sheaves shall generally have the same diameter as the drums. Intermediate deflector sheaves shall be provided, as necessary, to prevent rubbing of the ropes on fixed parts of the lift span and to avoid excessive unsupported lengths of rope. Lightly loaded intermediate deflector sheaves shall be supported on anti-friction bearings and shall be as light as practicable to ensure easy turning. All deflector sheaves shall have grooves sufficiently deep to prevent the ropes from being displaced.

13.6.5.5 Wire rope 13.6.5.5.1 General Unless otherwise specified in this Section, the manufacturing requirements for wire rope shall be in accordance with CSA G4.

13.6.5.5.2 Grade The wire for the ropes shall be either Grade 1770 or Grade 110/120 steel, bright finish, with a minimum tensile strength of 1770 MPa and 246 000 psi, respectively, and a maximum tensile strength as specified in Tables 13.1 and 13.2, respectively.

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Table 13.1 Maximum tensile strength for Grade 1770 bright wire (See Clause 13.6.5.5.2.)

Wire diameter, mm

Maximum tensile strength, MPa

0.20 to less than 0.50

2160

0.50 to less than 1.00

2120

1.00 to less than 1.50

2090

1.50 to less than 2.00

2060

2.00 to less than 5.00

2030

Table 13.2 Maximum tensile strength for Grade 110/120 bright wire (See Clause 13.6.5.5.2.)

Wire diameter, in

Maximum tensile strength, psi

0.007–0.019

302 000

0.020–0.038

298 000

0.039–0.058

293 000

0.059–0.078

289 000

0.079–0.097

284 000

0.098–0.147

284 000

0.148–0.196

284 000

13.6.5.5.3 Construction The ropes shall be 6 × 19 classification and the construction shall be 6 × 25 filler with fibre core.

13.6.5.5.4 Splicing Ropes or strands shall not be spliced. Wire splices shall be made by electric welding, and no two joints in any one strand shall be less than 7.5 m apart, except for filler wires.

13.6.5.5.5 Lay All wire ropes, unless otherwise specified by the Owner, shall be right regular lay, and the maximum length of rope lay shall be 6.75 times the nominal operating rope diameter or 7.5 times the nominal counterweight rope diameter. The lay of the wires in the strands shall be such as to make the wires approximately parallel to the axis of the rope where they would come in contact with a cylinder circumscribed on the rope.

13.6.5.5.6 Lubrication All portions of the wire ropes, including wires, strands, and cores, shall be thoroughly lubricated during fabrication with a lubricant containing a rust inhibitor. The lubricant shall be approved by the Engineer.

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13.6.5.5.7 Testing, inspection, and sampling The manufacturer shall provide proper and adequate facilities for testing, inspecting, and sampling wire ropes as specified in CSA G4. All tests shall be made in the presence of an inspector appointed by the Owner.

13.6.5.5.8 Tensile test on whole rope For the tensile test on whole rope, a test specimen of unused and undamaged wire rope shall be cut from each end of each continuous length of wire rope used for the finished lengths ordered. Each specimen shall have sockets of the same type and lot as those of the finished product attached at the ends. Additional test specimens may be required by the Engineer, but the total number of test specimens shall not exceed 10% of the total number of finished lengths of rope ordered, not including rejected specimens. The distance between sockets shall be at least 1.0 m for ropes less than 26 mm (1.0 in) in diameter and at least 1.5 m for ropes 26 mm (1.0 in) in diameter or larger. Each specimen shall be tested by applying a load not more than 60% of the ultimate strength specified in Table 13.13 with unrestricted crosshead speed; thereafter, the load shall be increased, with crosshead speed limited to 15 mm/min (0.5 in/min), until breakage occurs. If the specimen breaks within two wire diameters of the socket before the ultimate strength specified in Table 13.13 is attained, the tensile test shall be rejected and the test repeated. All test specimens shall develop the ultimate strength specified in Table 13.13. Failure of any valid specimen to pass the test shall be cause for rejection of the entire length of rope from which the specimen was taken, which shall be replaced by the manufacturer with a new length of rope of the same type. Note: See Clause 13.6.5.5.15 for testing of sockets.

13.6.5.5.9 Prestressing counterweight ropes Each counterweight rope shall be prestressed using the following procedure: (a) load the rope in tension to 40% of the ultimate strength specified in Table 13.13 and hold that load for 5 min; (b) reduce the load to 5% of the ultimate strength; (c) repeat this load-unload cycle two more times; and (d) release the load. Prestressing shall be carried out using rope lengths containing not more than two counterweight ropes. The rope shall be supported throughout its entire length at points not more than 7.5 m apart.

13.6.5.5.10 Length measurement of counterweight ropes 13.6.5.5.10.1 The length of each counterweight rope shall be taken as follows: (a) for open sockets: the distance between the centres of pins; (b) for closed sockets: the distance between bearings; and (c) for block sockets: the distance between bearing faces.

13.6.5.5.10.2 The following procedure shall be used in determining the correct rope length: (a) the rope shall be supported throughout its entire length at points not more than 7.5 m apart; (b) it shall be twisted until the lay is correct; and (c) it shall be measured under a tension of 12% of its ultimate strength (which corresponds to approximately the direct load on the rope).

13.6.5.5.10.3 Where rope attachment assemblies do not provide for rope length adjustment after installation, the length of all ropes shall be rechecked after socketing in accordance with the procedures specified in Clause 13.6.5.5.10.2. The checked rope length shall be corrected, if necessary, to bring it within the November 2006

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permissible variations in length by resocketing or other means approved by the Engineer. A durable tag or label shall be attached to each coil or reel of rope to indicate length, diameter, grade, construction, manufacturer’s name, order number, and destination. Each rope shall have a stripe painted along its entire length at the time that the length is measured. This stripe shall be straight after the rope is erected.

13.6.5.5.11 Length tolerance A maximum variation of ± 6 mm for every 30 m of rope length shall be allowed.

13.6.5.5.12 Operating ropes Operating ropes shall not be prestressed unless otherwise specified by the designer. When not socketed, the ends of operating ropes shall be seized and the ends of the rope wires shall be welded together. If necessary, the seizing may be removed before the ropes are attached to the drums.

13.6.5.5.13 Shipping Wire ropes shall be shipped on reels or coiled on wooden crosses. The diameter of the reel or the inside diameter of the coil shall be at least 25 times the diameter of the wire rope. The wire ropes shipped on reels shall be removed by revolving the reels. Ropes shipped on wooden crosses shall be securely lashed to one side of the cross and wood blocks shall be attached to the four arms so that each block makes contact with the inside of the coil to prevent movement during transit. Each rope shall be coiled on a separate reel of the same diameter for shipment.

13.6.5.5.14 Sockets Counterweight ropes shall have socketed end connections. Sockets, except block types, should be forged without welds from steel with an ultimate tensile stress of 445 to 515 MPa (65 000 to 75 000 psi) and be normalized. Cast steel sockets of open and closed types may be used for the larger sizes. Block sockets that provide for the direct load on the rope to be transmitted by bearing on the front face of the socket may be made from hot-rolled bars; retaining lugs may be welded on where necessary. The dimensions of all sockets shall be such that no part under tension will be stressed more than 445 MPa (65 000 psi) when the rope is loaded to its ultimate strength. All sockets shall be attached to the rope by a proven method that will not permit the rope to slip appreciably in its attachments.

13.6.5.5.15 Testing of sockets The rope test specified in Clause 13.6.5.5.8 shall also be used to test the sockets. If appreciable slipping in the sockets occurs during the test, the method of fastening the sockets to the rope shall be changed to the satisfaction of the Engineer to minimize the amount of slippage. The sockets shall be stronger than the rope to which they are attached. If a socket breaks during a test, other sockets shall be selected, attached to the rope, and the test repeated. This process shall be continued until the Engineer is satisfied as to the reliability of the sockets. If, however, 10% or more of the sockets tested break at a load less than the minimum ultimate strength of the rope specified in Table 13.13, the lot shall be rejected.

13.6.5.6 Wire rope attachment 13.6.5.6.1 Counterweight rope connections The connections of the counterweight ropes to the lift span and to the counterweights shall be such as to permit ready replacement of any one rope without disturbing the others. Provision shall also be made for the replacement of all ropes simultaneously. The connections of all ropes shall be such as to load all ropes of a group equally.

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13.6.5.6.2 Alignment of sockets The axis of the rope shall at all times be at right angles to the axis of the pin for open and closed sockets and to the bearing face for block sockets.

13.6.5.6.3 Operating rope connections Each operating rope shall have at least two full turns of the rope on the operating drum when the span is in the fully open or closed position. The end of the rope shall be clamped to the drum to avoid sharp bends in the wires. The dead end of each operating rope shall be attached to a device for taking up the slack in the rope.

13.6.5.6.4 Slapping ropes On the lift span side, the counterweight ropes shall be sufficiently separated to prevent objectionable slapping against each other while the span is in the closed position. This shall be accomplished by using widely spaced grooves on the sheaves, by deviating alternate ropes in vertical planes, or by another means approved by the Engineer.

13.7 Structural analysis and design 13.7.1 General Clauses 13.7.2 to 13.7.19 apply to bridges for which the moving span is normally left in the closed position. When the bridges are in the closed position, all of the requirements of this Code relating to fixed bridges shall apply. Clauses 13.7.2 to 13.7.19 apply specifically to the design of movable bridges when they are in the operating mode or in the open position, to swing bridges that are closed but whose ends are just touching, and to bascule and vertical lift bridges that are closed but whose counterweights are supported for repairs. The special load combinations in Tables 13.3 to 13.5 do not include load combinations for substructure designs.

13.7.2 Design theory and assumptions The design theory and assumptions specified in other Sections of this Code shall apply to movable bridges, except that the loads, load factors, and load combinations specified in Clauses 13.7.3 to 13.7.19 shall also be considered.

13.7.3 Wind loads 13.7.3.1 General The loads and related areas specified in Clauses 13.7.3.2 to 13.7.3.10 shall be used in proportioning members and determining stability.

13.7.3.2 Horizontal transverse wind, normal to centreline For girder spans, the surface area shall be considered to be 1.5 times the vertical projection of the span, including the deck and railing, plus the vertical projection of any counterweight. For truss spans, the surface area shall be considered to be the vertical projection of the floor system and any counterweight, plus twice the vertical projection of the members of one truss.

13.7.3.3 Horizontal longitudinal wind, parallel to centreline For bascule (including rolling lift) bridges, the surface area shall be considered to be the vertical projection of the floor plan area and those portions of the vertical projection of the counterweight, where applicable, that are not shielded by the floor plan area. The floor plan area of a bridge with an open deck shall not be

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considered to be shielding other parts of the structure. For vertical lift bridges, the total longitudinal wind force acting on the moving span shall be assumed to be 50% of the total transverse wind force acting on the span and to act through the same centre of gravity.

13.7.3.4 Vertical wind, normal to the floor plan area For swing bridges, the surface area shall be the floor plan area of the larger arm. For vertical lift bridges, the surface area shall be the floor plan area.

13.7.3.5 Floor plan area The floor plan area exposed to wind or ice shall be taken as a quadrilateral whose length is equal to that of the floor of the moving span and whose width is that of the distance out-to-out of trusses, girders, or sidewalks, whichever gives the greatest width. For bridges decked with open steel grating, the floor plan area of the grating shall be assumed to be 85% of the floor plan area of a solid deck.

13.7.3.6 Operator’s house and machinery house If the operator’s house, the machinery house, or both are located on the moving span, their projected areas shall be included in the surface area for wind, except for portions shielded by the floor plan area. Open decks shall not be considered to be shielding.

13.7.3.7 Towers and their bracing Exposed areas for transverse and longitudinal wind loads on towers and their bracing shall include the vertical projections of all columns and bracing not shielded by the counterweights and houses.

13.7.3.8 Swing bridges The horizontal transverse wind pressure shall be 1.2 kPa on one arm and 1.70 kPa on the other arm. The vertical wind pressure shall be 0.25 kPa on the floor plan area of one arm; in the case of unequal arm bridges, the floor plan area of the longer arm shall be used.

13.7.3.9 Bascule (including rolling lift) bridges The horizontal transverse wind pressure shall be 1.50 kPa and the horizontal longitudinal wind pressure shall be 1.50 kPa.

13.7.3.10 Vertical lift bridges The horizontal transverse wind pressure shall be 1.50 kPa and the horizontal longitudinal wind pressure shall be 1.50 kPa, except as specified in Clause 13.7.3.3. The vertical wind pressure shall be 0.25 kPa on the floor plan area.

13.7.4 Seismic loads For design with the movable spans in the closed position, seismic loads shall be as specified in Sections 3 and 4. For design with the movable spans in the open position, the seismic loads shall be one-half of those specified in Sections 3 and 4.

13.7.5 Reaction due to temperature differential For swing bridges, provision shall be made for an end reaction due to the following temperature differentials: (a) between the top and bottom chords of a truss: 10 °C; and (b) between the top and bottom flanges of a girder: 8 °C. Load combinations ULS 2, ULS 3, and ULS 4 of Section 3 shall apply.

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13.7.6 Hydraulic cylinder connections The loads on the structural connections to the cylinders shall be based on the maximum of (a) wind, ice, inertia, or other structural loads, assuming the cylinder as a rigid link; and (b) driving and braking mechanical loads, assuming a cylinder force developed by 150% of the setting of the pressure-relief valve that controls the maximum pressure available at the cylinder.

13.7.7 Loads on end floor beams and stringer brackets The end floor beams and stringer brackets of the moving span shall be proportioned for at least the factored dead load and factored live load plus twice the factored dynamic load allowance.

13.7.8 Swing bridges — Ultimate limit states 13.7.8.1 Closed position In the closed position, the bridge ends are lifted to give a positive reaction equal to 150% of the maximum negative reaction due to live load and dynamic load allowance. For this position, load combinations ULS 1 to ULS 8 of Section 3 shall apply.

13.7.8.2 Special load combinations and load factors In addition to load combinations ULS 1 to ULS 8 of Section 3, the special load combinations and load factors specified in Table 13.3 shall be considered. 

Table 13.3 Swing bridges — Special load combinations and load factors (See Clauses 13.7.1 and 13.7.8.2.) Load combination

Do*

Ls

Lc

Wo

Io

Mo

ULS S1 ULS S2 ULS S3 ULS S4 ULS S5 ULS S6 ULS S7

D D D D D D D

0 1.70 0 1.40 0 0 0

0 0 1.70 0 1.40 0 0

0 0 0 1.20 1.20 1.20 1.50

1.20 0 0 0 0 1.20 1.20

1.55 0 0 0 0 1.25 0

*See Table 13.6 for values of D. Notes: (1) When the ends are being lifted, the loading combination and load factors are similar to ULS S1 except that there are different machinery forces and there are forces at the ends. (2) For any combination, the minimum or maximum value of the load factor,  D , shall be used so as to maximize the total force effect. Legend: Do = dead load; bridge open in any position or closed with ends just touching Ls = live load (including dynamic load allowance) on one arm as a simple span; bridge closed with ends just touching Lc = live load (including dynamic load allowance); bridge closed with ends just touching, with bridge considered as a continuous structure; reactions at both ends to be positive Wo = wind load; bridge open in any position or closed with ends just touching Io = operating impact of 20% applied to the maximum dead load effect in all members that are in motion and to the load effect on a stationary member caused by the moving dead load Mo = maximum forces on structural parts caused by the operation of machinery, or by forces applied for moving or stopping the span, increased 100% as an allowance for impact

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13.7.8.3 Stationary in open position In the event that a movable bridge is required to remain open or can be stuck in the open position, the requirements of Section 3 for wind loads on a fixed bridge shall apply.

13.7.9 Bascule (including rolling lift) bridges — Ultimate limit states 13.7.9.1 Closed position When the bridge is not in operating mode and the counterweight is not temporarily supported for repairs, load combinations ULS 1 to ULS 8 of Section 3 shall apply.

13.7.9.2 Special load combinations and load factors In addition to load combinations ULS 1 to ULS 8 of Section 3, the special load combinations and load factors specified in Table 13.4 shall be considered. 

Table 13.4 Bascule (including rolling lift) bridges — Special load combinations and load factors (See Clauses 13.7.1 and 13.7.9.2.) Load combination

Do*

Dt*

Lt

Ho

Wo

Io

Mo

ULS B1 ULS B2 ULS B3 ULS B4 ULS B5

D D D D

0 0 0 0

0 0 0 0 1.70

0 0 0 1.55 0

0 1.20 1.50 0 0

1.2 1.2 1.2 1.2 0

1.55 1.25 0 1.55 0

0

D

*See Table 13.6 for values of D. Notes: (1) Combination ULS B4 applies only to those parts of the structure that support trunnions of the moving span and/or counterweight. (2) For any combination, the minimum or maximum value of the dead load factor,  D , specified in Section 3 shall be used to maximize the total force effects. Legend: Do = dead load; bridge open in any position or closed with ends just touching Dt = dead load; bridge closed; counterweight supported for repairs Lt = live load (including dynamic load allowance); bridge closed; counterweight supported for repairs Ho = horizontal force, taken as 5% of the total moving load carried by the steel towers and/or special parts of the structure that support the counterweight assembly; bridge open in any position; this force shall be applied in any direction, through the centre of gravity of the moving load Wo = wind load; bridge open in any position or closed with ends just touching Io = operating impact of 20% applied to the maximum dead load effect in all members that are in motion and to the load effect on a stationary member caused by the moving dead load Mo = maximum forces on structural parts caused by the operation of machinery, or by forces applied for moving or stopping the span, increased 100% as an allowance for impact

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13.7.10 Vertical lift bridges — Ultimate limit states 13.7.10.1 Closed position When the bridge is not in operating mode and the counterweight is not temporarily supported for repairs, load combinations ULS 1 to ULS 8 of Section 3 shall apply.

13.7.10.2 Special load combinations and load factors In addition to load combinations ULS 1 to ULS 8 of Section 3, the special load combinations and load factors specified in Table 13.5 shall be considered. 

Table 13.5 Vertical lift bridges — Special load combinations and load factors (See Clauses 13.7.1 and 13.7.10.2.) Load combination

Do*

Dt*

Lt

Wo

Io

Mo

ULS V1 ULS V2 ULS V3 ULS V4

D D D

0 0 0

0 0 0 1.70

0 1.20 1.50 0

1.2 1.2 1.2 0

1.55 1.25 0 0

0

D

*See Table 13.6 for values of D. Note: For any combination, the minimum or maximum value of the dead load factor,  D , shall be used to maximize the total force effects. Legend: Do = dead load; bridge open in any position or closed with ends just touching Dt = dead load; bridge closed; counterweight supported for repairs Lt = live load (including dynamic load allowance); bridge closed; counterweight supported for repairs Wo = wind load; bridge open in any position or closed with ends just touching Io = operating impact of 20% applied to the maximum dead load effect in all members that are in motion and to the load effect on a stationary member caused by the moving dead load Mo = maximum forces on structural parts caused by the operation of machinery, or by forces applied for moving or stopping the span, increased 100% as an allowance for impact

13.7.11 Dead load factor

The dead load factor,  D , in Tables 13.3 to 13.5 shall be as specified in Table 13.6.

Table 13.6 Dead load factor,  D (See Clause 13.7.11 and Tables 13.3–13.5.) Dead load type

Maximum

Minimum

D1 — Factory-produced components D2 — Cast-in-place concrete and wood D3 — Wearing surface

1.20 1.40 1.40

0.90 0.80 0.75

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13.7.12 All movable bridges — Ultimate limit states Longitudinal wind shall be included in the design of the superstructure for load combinations ULS 3, ULS 4, and ULS 7 of Section 3. For seismic loading with the bridge open, load combination ULS 5 of Section 3, as modified by Clause 13.7.4, shall apply. For vessel collisions with the bridge operating, load combination ULS 8 of Section 3 shall apply.

13.7.13 Special types of movable bridges The analysis of special types of movable bridges shall be carried out for all applicable load conditions. The members shall be proportioned for total factored load effects in accordance with the requirements specified in this Section for the design of fixed, swing, bascule, and vertical lift bridges.

13.7.14 Load effects A drawing shall be prepared showing the load effects for the various analyses and the total factored load effects for the applicable combinations in the different primary members at appropriate locations.

13.7.15 Fatigue limit state The stress range arising from the operation of the span from the fully closed to the fully open position and back to the fully closed position, including the effect of wind, shall be less than the allowable stress range specified in Section 10, based on the estimated number of load cycles. This Clause shall also apply to members and/or steel that are embedded in or encase counterweights and either support the mass or transfer the load to the main structure, and to the connections of such members.

13.7.16 Friction Consideration shall be given to bending stresses arising from pin, journal, trunnion, and other friction.

13.7.17 Machinery supports All structural parts supporting machinery shall be of ample strength and rigidity and be designed to minimize vibration.

13.7.18 Vertical lift bridge towers The lateral bracing of vertical lift bridge towers shall be designed for 2.5% of the total compression in the columns in addition to the specified wind loads.

13.7.19 Transitory loads Transitory loads, e.g., operating impact, shall be included in the loading combinations only if their inclusion increases the total factored load effect.

13.8 Mechanical system design 13.8.1 General Because mechanical system design in North America is based mainly on working stress design, the requirements of Clauses 13.8.2 to 13.8.20 are specified in terms of working stress even though other clauses of this Code are based on limit states design. Most North American textbooks on mechanical system design use foot/pound units. Accordingly, where a value was originally expressed in foot/pound units, Clause 13.8 provides the foot/pound value in parentheses, accompanied by a soft-converted SI value.

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13.8.2 Operating machinery The design and construction of operating machinery shall be such that it requires minimum maintenance. All working parts shall be arranged so that they can be easily erected, adjusted, and dismantled. Fastenings shall be designed so that all machinery parts, after they are set, aligned, and adjusted, will be securely and rigidly connected. All machinery shall have moving parts fitted with the guards or other safety devices required by applicable safety codes.

13.8.3 Power sources Movable bridges should be operated by electric power. If two independent sources of electric power are procurable, both should be made available for bridge operation. Movable bridges may also be operated by internal combustion engines or human effort, depending on local conditions.

13.8.4 Prime mover 13.8.4.1 Emergency prime mover A movable bridge may be provided with an emergency prime mover for operation of the bridge in case of failure of the prime mover or power supply normally used. The emergency prime mover may be one of the following types: (a) an electric motor that has controls independent of those provided for normal operation and a power source independent of that normally used for bridge operation, e.g., a generator driven by an internal combustion engine or a motor-generator set powered by a storage battery unit (its power characteristics may be different from those of the normal power source); (b) an internal combustion engine; (c) an air motor; (d) hydraulics; or (e) human effort. The emergency prime mover may operate the bridge at a slower speed than the prime mover. No emergency prime mover need be furnished where two independent and normally reliable sources of electric power with identical characteristics are made available and twin electric motors with independent controls are provided for each set of operating machinery. For twin motors, the capacity of each shall be such that, in the event of the failure of one, the other can still drive the bridge through the independent control in about the same time under the same conditions.

13.8.4.2 Locks, wedges, lights, signals, and traffic gates Where two independent and normally reliable sources of electric power with identical characteristics are made available, no additional source of power need be provided for operating locks, wedges, lights, signals, and traffic gates. If only one electric power service is available, an engine-generator set shall also be supplied. It shall be of sufficient capacity to provide power for the operation of the following electrically powered devices: (a) span locks; (b) traffic gates and their lights; (c) traffic signal lights; (d) pier lights; (e) navigation lights on the span; (f) vital indicating lights on the control desk; (g) a sufficient number of lights in the control house, in the machinery room, and on stairways to enable the operator to move about safely; and (h) release of electric brakes for main machinery. The starting up of this engine-generator set may be automatic on the failure of the main electrical power supply. A transfer switch shall be provided to enable the operator to switch over from the main to the emergency power supply and vice versa. An indicating light with a suitable label shall be supplied and installed on the operator’s desk to indicate that electric power is being supplied by the emergency November 2006

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engine-generator set. A holding circuit shall also be supplied to bypass the automatic start-up feature, enabling the set to supply power until stopped by the operator pressing a “stop” push-button switch. If driven by an electric or any other type of mechanical prime mover, the machinery for operating span locks, wedges, traffic gates, or any other devices essential to the operation of the bridge shall also be capable of being operated by human effort or other independent means if the normal prime mover fails.

13.8.5 Power requirements for main machinery 13.8.5.1 General Power shall be provided, and machinery shall be designed to operate the bridge within the times specified in Clauses 13.8.5.2 and 13.8.5.3 and to hold the bridge in any position, under the conditions specified in Clauses 13.8.5.2 to 13.8.5.4.

13.8.5.2 Case A In the normal time for opening, as follows: (a) Swing bridges: against frictional resistances, inertia, and a horizontal wind pressure of 0.12 kPa on one arm and a wind pressure of 0.24 kPa on the other (the longer arm, if the arms are unequal) acting on the vertical surfaces specified in Clause 13.7.3. (b) Bascule bridges (including rolling lift bridges): against frictional resistances, inertia, unbalance (if any), and a wind pressure of 0.12 kPa acting normal to the floor acting on the applicable surfaces specified in Clause 13.7.3. (c) Vertical lift bridges: against frictional resistances, inertia, unbalance (if any), rope bending, and a wind pressure of 0.12 kPa acting normal to the floor, acting on the applicable surfaces specified in Clause 13.7.3. The wind load shall be considered to include the frictional resistances from span and counterweight guides caused by horizontal wind on the moving span.

13.8.5.3 Case B In excess of the normal time for opening, as follows: (a) Swing bridges: against frictional resistances, inertia, and a horizontal wind pressure of 0.24 kPa on one arm and a wind pressure of 0.48 kPa on the other (the longer arm, if the arms are unequal) plus an ice loading of 0.12 kPa on the floor, acting on the applicable surfaces specified in Clause 13.7.3. (b) Bascule bridges (including rolling lift bridges): against frictional resistances, inertia, unbalance (if any), and a horizontal wind pressure of 0.24 kPa acting on the open bridge, plus an ice loading of 0.12 kPa on the floor, acting on the applicable surfaces specified in Clause 13.7.3. (c) Vertical lift bridges: against frictional resistances, inertia, unbalance (if any), rope bending, and a wind pressure of 0.12 kPa plus an ice loading of 0.12 kPa, all acting normal to the floor, acting on the applicable surfaces specified in Clause 13.7.3. Frictional resistances from the span and counterweight guides shall be considered to be included in the loads specified in this Item.

13.8.5.4 Case C Bridge held in any open position or operating position, as follows: (a) Swing bridges: against a horizontal wind pressure of 0.96 kPa acting on one arm and a wind pressure of 1.44 kPa on the other (the longer arm, if the arms are unequal) acting on the applicable surfaces specified in Clause 13.7.3. (b) Bascule bridges (including rolling lift bridges): against a horizontal wind pressure of 0.96 kPa acting on the open bridge on the applicable surfaces specified in Clause 13.7.3. (c) Vertical lift bridges: against the wind and ice loads specified in Clause 13.8.5.3(c).

13.8.6 Wedges The end-lift machinery of swing bridges shall be capable of lifting and supporting the span sufficiently to ensure a positive reaction under all conditions of live load and to remove any deflection due to temperature variations. The centre-wedge machinery of swing bridges shall be capable of driving the wedges to a position where they will provide an adequate reaction for the live load.

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13.8.7 Brakes 13.8.7.1 General 13.8.7.1.1 General Movable bridge spans shall have at least one set of brakes. Bridges that are manually operated only may be provided with only one set of brakes. This set shall consist of two units. One brake unit shall be considered equivalent to a motor brake and the other brake unit shall be proportioned to assist in dynamic braking for emergency stopping or to assist in static braking or “parking” the span in any position and shall be considered equivalent to a machinery brake. Each drive unit on a power-operated movable bridge shall have at least two sets of brakes. One set shall be a motor brake in accordance with Clause 13.8.7.2 and the other shall be either a motor brake in accordance with Clause 13.8.7.2 or a machinery brake in accordance with Clause 13.8.7.3. For the purposes of this Clause, a set of brakes may consist of one or more individual braking units. Hydraulically operated bridges shall be provided with equivalent means for motion control.

13.8.7.1.2 Operating The motor brakes for controlling the motion of the moving span shall have sufficient capacity to stop the span in 10 s under the loading conditions specified in Clause 13.8.5.2 for bridge operation in the normal time for opening or closing.

13.8.7.1.3 Holding The braking systems shall also be capable of holding the span against movement in any open position under the loads specified in Clause 13.8.5.4.

13.8.7.1.4 Gradual application Brakes, whether electrically, mechanically, hydraulically, or manually operated, shall be designed so that the retarding torque is applied gradually and is consistent with the deceleration time assumed for design in order to minimize shock loading.

13.8.7.1.5 Sequencing When two sets of brakes are used, they shall be sequenced so that under normal operation they cannot be applied simultaneously.

13.8.7.1.6 Frictional assistance In calculating the necessary brake capacity, frictional resistances that assist the brake may be included. Coefficients of friction that are 40% of those related to motion may be used for this condition.

13.8.7.2 Motor brakes Motor brakes shall be provided for all movable bridges. Where only one set of brakes is fitted, the motor brakes shall be capable of controlling the span for both the operating and the holding conditions. Motor brakes shall be operated either electrically or mechanically. On electric motor installations, they should be electrically operated and mounted on the motor shaft. On internal combustion engine and manually operated installations, they shall be mounted as near to the high-speed shaft as practicable.

13.8.7.3 Machinery brakes When machinery brakes are supplied, the motor brakes shall have sufficient capacity to stop the span in 10 s and the machinery brakes shall have a capacity, as measured at the shafts of the motor brakes, equal to 50% of that of the motor brakes. The combined capacity of the motor and machinery brakes shall be sufficient to hold the span under the conditions specified in Clause 13.8.5.

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The machinery brakes shall normally be held in release during the entire operating cycle but shall be capable of being applied in an emergency at the discretion of the operator. They shall be designed to be held in release indefinitely. The machinery brakes shall be mounted as near as practicable to the operating ropes or main pinion.

13.8.7.4 Brakes for emergency power When emergency power by means of an internal combustion engine is used, a manually operated brake that is capable of being applied by the operator from the point at which the engine is being operated shall be provided. Brakes shall not be required for emergency manual operation.

13.8.7.5 Brakes for locks and wedge motors Span lock and wedge motors shall each have one electrically operated brake.

13.8.8 Frictional resistance 13.8.8.1 Machinery The frictional resistances of the moving span and its machinery parts shall be determined using the coefficients specified in Tables 13.7 and 13.8.

Table 13.7 Coefficients of friction (See Clause 13.8.8.1.) Coefficient of friction

For trunnion friction, plain bearings Less than one complete revolution More than one complete revolution For trunnion friction, anti-friction bearings For friction on centre discs For collar friction at ends of conical rollers For rolling friction Bridges rolling on segmental girders Rollers with flanges Rollers without flanges r measured in millimetres r measured in inches For sliding surfaces, intermittently lubricated (e.g., span guides of vertical lift bridges)

For starting

For moving

0.18* 0.13* 0.004 0.15 0.15

0.12* 0.09* 0.003 0.10 0.10

0.009 0.009

0.006 0.006

0.04/ r 0.08/ r 0.12

0.04/ r 0.08/ r 0.08

*For manually operated bridges, this coefficient shall be increased by 25%. For proprietary bearing materials, the coefficients of friction shall be as specified by the manufacturer. Note: For wire rope bending through a 180° wrap, the loss per sheave is the direct tension multiplied by 0.3(dr /D) for starting and moving. Legend: r = radius of roller, mm (in) dr = rope diameter, mm (in) D = pitch diameter of sheaf or drum, mm (in)

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Table 13.8 Machinery losses and efficiency coefficients (See Clause 13.8.8.1.) Coefficient Machinery losses

For journal friction, plain bearings For journal friction, anti-friction bearings For friction at thrust collars* Screw gearing, bronze on steel

Efficiency coefficients

Journal friction included, for efficiency of any pair of gears Plain bearings Spur gears Bevel gears, collar friction included Anti-friction bearings Spur gears Bevel gears, collar friction included Worm gearing, collar friction not included

0.05 0.01 0.10 0.10

0.95 0.87 0.98 0.90 Np/(Np + R)

*Where anti-friction thrust collars are used, the thrust bearing friction may be neglected. Legend: N = number of threads of lead of worm p = circular pitch of teeth on wheel R = radius of worm, mm (in)

13.8.8.2 Locks and Wedges For sliding span locks and end and centre wedges, the coefficients of friction specified in Table 13.9 shall be used for steel on bronze.

Table 13.9 Coefficients of friction for sliding span locks and end and centre wedges (See Clause 13.8.8.2.)

Top surfaces Bottom surfaces

For starting

For moving

0.15 0.20

0.10 0.15

13.8.9 Torque 13.8.9.1 Torque at prime mover for main machinery The sum of all resistances specified in Clause 13.8.8, with the addition of the machinery resistances, shall be reduced to a starting, accelerating, and running torque on the prime mover (referred to as “bridge torque” in Clause 13.8.9).

13.8.9.2 Starting torque In calculating the bridge torque for starting conditions, the torque required to overcome inertia need not be included except for swing spans.

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13.8.9.3 Time for determining torque required for acceleration A period of 10 to 15 s shall be allowed for determining the torque required for acceleration.

13.8.9.4 Torque at prime mover for locks and wedges For span lock and wedge machinery, the sum of all resistances to be overcome shall be reduced to a single equivalent torque at the prime mover.

13.8.9.5 Torque of prime mover for main machinery 13.8.9.5.1 Electric motors Where electric motors are used as prime movers, they shall be capable of developing the following minimum torques at voltage within ±10% of normal voltage, starting cold, for the loading conditions and time intervals specified in Clause 13.8.5: (a) Single-motor prime mover: (i) For operation against the loading conditions specified in Clause 13.8.5.2, the bridge torque for starting or accelerating, whichever is larger, shall not be more than 125% of the rated full-load torque of the motor. (ii) For operation against the loading conditions specified in Clause 13.8.5.3, the bridge torque for running after acceleration shall be not more than 125% of the rated full-load torque of the motor or more than 180% of the rated full-load torque for starting or accelerating, whichever is larger. (b) Twin-motor prime mover: (i) Where twin motors are used for joint operation, the two motors together shall meet the requirements specified for single-motor installations in Item (a). (ii) Where twin motors are used for alternate operations, each motor shall meet the requirements specified for single-motor installations in Item (a).

13.8.9.5.2 Internal combustion engines The rated engine torque (i.e., the torque measured at the flywheel, at the speed to be used for operation, with the radiator, fan, housings, and all other power-consuming accessories in place), shall be not more than 85% of the manufacturer’s torque rating of the stripped engine. Where engines are used as the prime mover, they shall be capable of developing minimum rated engine torques that exceed the maximum bridge torques by the following percentages: (a) 33% for engines of four or more cylinders; and (b) 50% for engines of three or fewer cylinders.

13.8.9.5.3 Worker power The gear ratio shall be such that the number of persons assumed to be available for bridge operation is capable of developing the required maximum bridge torque.

13.8.9.6 Torque for lock and wedge machinery Where span locks and wedges are operated by electric motors, the torque for starting or running shall not be more than 150% of the full-load torque of the motor, but in no case shall a motor of less than 1.5 kW (2 hp) be used. Where span locks and wedges are operated by human effort, the gear ratio shall be such that the number of persons available for bridge operation shall be capable of delivering a torque equal to the maximum torque. Where span locks and wedges are operated by hydraulic systems, the hydraulic systems shall be capable of providing 150% of the maximum torque or an equivalent force at the normal operating pressure.

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13.8.10 Application of worker power Worker power may be applied by capstans, cranks, hand chains, or levers, assuming that each worker employed thereon shall do work continuously as follows: (a) Push 0.135 kN (30 lb) on a capstan handle while walking at a rate of 60 m (200 ft) per minute, or push 0.175 kN (40 lb) on a capstan handle while walking at a rate of 50 m (160 ft) per minute. The force shall be assumed to be applied 250 mm (10 in) from the end of the capstan handle, and the spacing of additional worker on the same handle shall be assumed to be 600 mm. (b) Turn a crank having a radius of 375 mm (15 in) by exerting a force of 0.135 kN (30 lb) at a rate of 15 revolutions per minute. (c) Exert a pull of 0.260 kN (60 lb) on a hand chain at a rate of 20 m (70 ft) per minute. (d) Apply a force of 0.440 kN (100 lb) on the extreme end of a brake lever or a force of 0.590 kN (130 lb) on a foot pedal. For starting conditions, it shall be assumed that a worker will, for a short time, exert twice the forces specified in Items (a) to (c).

13.8.11 Machinery loads All machinery parts whose failure could interfere with the operation of the bridge or impair its safety shall be proportioned for the following loads, as shall the connections of such parts, the members to which such parts can be attached, and any other members affected by such parts: (a) machinery driven by electric motors shall be designed for 150% of the rated full-load torque of the motor or motors at normal unit stresses; (b) machinery driven by internal combustion engines shall be designed for 100% of the rated engine torque at normal unit stresses; (c) machinery operated by worker power or machinery parts under the action of manually operated brakes shall be designed for 133% of the torque specified under Clause 13.8.10 at normal unit stresses; and (d) machinery operated by hydraulic systems shall be designed for 100% of the maximum hydraulic system relief valve pressure. For the wind and ice loads specified in Clause 13.8.5.4, the allowable unit stresses specified in Clause 13.8.12 may be increased by 50%.

13.8.12 Allowable stresses for machinery and allowable hydraulic pressures 13.8.12.1 Machinery materials The maximum allowable stresses specified in Tables 13.10 and 13.11 shall be used for the design of machinery and those parts of the structure directly affected by vibrational or shock loads from the machinery, e.g., machinery supports. Where materials of different strengths are in contact, the fixed bearing and shear values of the weaker material shall govern. For rotating parts and frames, pedestals, and other units that support rotating parts, the calculated stresses shall be multiplied by an impact factor K, as follows: (a) for trunnions and counterweight sheaves, K = 1.0; and (b) for other rotating parts, K = 1.0 + 0.03n0.5, where n is the number of revolutions per minute of the rotating part. All of the stresses specified in Tables 13.10 and 13.11 include allowances for reversal, stress concentration factors up to 1.4, keyways of normal proportions, and good design details.

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Table 13.10 Maximum allowable stresses in trunnions, MPa (psi) (See Clause 13.8.12.1 and Table 13.12.) Rotation more than 180°

Rotation 90° or less

Fixed trunnions

Forged carbon steel, ASTM A 668/A 668M, Class D

69 (10 000)

103 (15 000)

117 (17 000)

Forged alloy steel, ASTM A 668/A 668M, Class G

69 (10 000)

138 (20 000)

152 (22 000)

Table 13.11 Maximum allowable stresses for machinery parts other than trunnions, MPa (psi) (See Clauses 13.8.12.1, 13.8.16.1, and 13.8.17.4.3 and Table 13.12.) Specification Material

CSA

ASTM

Tension

Compression

Fixed bearing

Shear

Structural steel

G40.21, Grade 300W or 300WT

A 36M

83

83 – 0.38l/r

110

41

G40.21, Grade 300W or 300WT

A 36

(12 000)

(12 000 – 55l/r)

(16 000)

(6000)

Forged carbon steel (except keys)

A 668M, Class D A 668, Class D

103 (15 000)

103 – 0.45l/r (15 000 – 65l/r)

124 (18 000)

52 (7500)

Forged carbon steel keys

A 668M, Class D A 668, Class D

— —

— —

103 (15 000)

52 (7500)

Forged alloy steel

A 668M, Class G A 668, Class G

110 (16 000)

110 – 0.48l/r (16 000 – 70l/r)

145 (21 000)

55 (8000)

Cast steel

A 27M, Grade 485-250 A 27, Grade 70-36

62 (9000)

69 – 0.31l/r (10 000 – 45l/r)

90 (13 000)

34 (5000)

A 148M, Grade 620-415 A 148, Grade 90-60

103 (15 000)

103 – 0.45l/r (15 000 – 65l/r)

145 (21 000)

55 (8000)

Cast iron

A 48M, Class 200 A 48, Class 30

14 (2000)

69* (10 000)*

— —

— —

Bronze

B 22, Alloy 905

48 (7000)

48 (7000)

— —

— —

Hot-rolled steel bars

A 675M, Grade 515 A 675, Grade 75

83 (12 000)

83 – 0.38l/r (12 000 – 55l/r)

110 (16 000)

41 (6000)

*For struts whose l /r is 20 or less.

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Canadian Highway Bridge Design Code

13.8.12.2 Hydraulic systems and components 13.8.12.2.1 Allowable system pressures The hydraulic system shall be designed and the hydraulic components proportioned in such a manner that the maximum system pressures shall not exceed the following, except as approved in writing by the Engineer: (a) normal operation: 6.9 MPa (1000 psi); (b) operation against maximum specified wind loads: 13.8 MPa (2000 psi); and (c) holding against maximum specified wind loads: 20.7 MPa (3000 psi). Normal operation shall be defined as operation against the Case A loads specified in Clause 13.8.5.2. Operation against maximum specified loads shall be defined as operation against the Case B loads specified in Clause 13.8.5.3. Holding against maximum specified wind loads shall be defined as holding the movable span against the Case C loads specified in Clause 13.8.5.4.

13.8.12.2.2 Pressure ratings for hydraulic components 13.8.12.2.2.1 The minimum working pressure ratings for hydraulic components shall be as follows, except as approved in writing by the Engineer: (a) pipes, tubing, and their fittings: 20.7 MPa (3000 psi); and (b) flexible hose and hose fittings: (i) for pressure lines: 34.5 MPa (5000 psi); (ii) for drain lines: 13.8 MPa (2000 psi); and (iii) for cylinders, pumps, valves, and all other components: 20.7 MPa (3000 psi).

13.8.12.2.2.2 The working pressure rating shall be defined as the maximum allowable continuous operating pressure for the component. For pipes, tubing, flexible hose, and fittings, the working pressure rating shall be the burst pressure rating divided by a minimum safety factor of 4. For cylinders, the working pressure rating shall be equal to the National Fluid Power Association theoretical static failure pressure rating required by Article 6.5.37.11 of Chapter 15 of the AREMA Manual for Railway Engineering, divided by a minimum safety factor of 3.33. For pumps, valves, and other components, the working pressure rating shall be the maximum allowable peak (intermittent) pressure rating divided by a minimum safety factor of 1.5.

13.8.12.2.2.3 The minimum safety factors specified in Clause 13.8.12.2.2.2 shall apply to systems with light-to-moderate operating shock loads during operation, resulting in short-duration peak system pressures not greater than twice the allowable maximum operating pressure against Clause 13.8.5.3 Case B loads or Clause 13.8.5.4 Case C loads, whichever are greater. For systems with higher shock load pressures, the safety factors shall be increased proportionally.

13.8.13 Bearing pressures (moving surfaces) 13.8.13.1 Maximum bearing pressures The maximum bearing pressures specified in Table 13.12 shall be used in proportioning rotating and sliding surfaces. Bearing pressures greater than the maximum values specified in Table 13.12 may be used where the maximum loading occurs only during a small part of the motion cycle or in other cases deemed appropriate, provided that special precautions are taken with respect to surface finish and lubrication. The greater bearing pressures shall be subject to the approval of the Engineer.

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13.8.13.2 Determination of bearing pressures For the slow-moving parts specified in section A of Table 13.12, bearing pressures shall be calculated on the net projected area, i.e., after deducting the area of oil grooves, etc. For the higher-speed moving and rotating parts specified in sections B, C, and D of Table 13.12, bearing pressures shall be calculated on the gross projected area.

Table 13.12 Maximum bearing pressures (See Clauses 13.8.13.1, 13.8.13.2, and 13.8.17.4.3.) Maximum bearing pressure, MPa (psi)

Condition

Parts

Material*

A. Motion: speeds 15 m/min (50 ft/min) or less

Pivots for swing bridges

Hardened steel on ASTM B 22 Alloy 911 bronze Hardened steel on ASTM B 22 Alloy 913 bronze

17 (2500)

Trunnion bearings of bascules and counterweight sheave bearings of vertical lifts

Rolled or forged steel on ASTM B 22 Alloy 911 bronze

For loads in motion: 10 (1500) For loads at rest: 14 (2000)

Wedges

Cast steel on ASTM B 22 Alloy 911 bronze 8 (1200) Cast steel on ASTM B 22 Alloy 913 bronze 10 (1500)

Bearings for main pinion shafts and other heavily loaded shafts

Rolled or forged steel on ASTM B 22 Alloy 937 bronze

7 (1000)

Other bearings

Steel journals on babbitt Steel journals on ASTM B 22 Alloy 937 bronze

2.8 (400) 4 (600)

Step bearings for vertical shafts

Hardened steel shaft end on ASTM B 22 Alloy 937 bronze ASTM B 22 Alloy 911 bronze

B. Motion: speeds over 15 m/min (50 ft/min) but less than 30 m/min (100 ft/min)

21 (3000)

4 (600) 8 (1200)

Thrust collars

Rolled or forged steel on ASTM B 22 Alloy 937 bronze

1.4 (200)

Acme screws that transmit motion

Rolled or forged steel on ASTM B 22 Alloy 905 bronze

10 (1500)

C. Motion: speeds of 30 m/min (100 ft/min) and more†

Journals

Rolled or forged steel on bronze

43.8/nd (250 000/nd)

Step bearings

Hardened steel on bronze

10.5/nd (60 000/nd)

Thrust collars

Rolled or forged steel on bronze

8.8/nd (50 000/nd)

Acme screws that transmit motion

Rolled or forged steel on bronze

38.5/nd (220 000/nd)

D. Alternating motion

Crank pins and similar parts with — alternating application and release of pressure

‡

*The materials specified in this column shall comply with the Standards specified in Tables 13.10 and 13.11. Alternative bearing materials may be considered. The maximum bearing pressures of such alternative materials shall conform to the manufacturer’s recommendations. †n = number of revolutions per minute and d = diameter of journal or step bearing or mean diameter of collar or screw, mm (in). To prevent heating and seizing at higher speeds, the pressures derived from the formulas in section C of this Table shall not be exceeded and shall never be greater than 75% of the values permitted by section B of this Table. ‡The limiting bearing pressure determined in accordance with the formula for journals in section C of this Table may be doubled.

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13.8.14 Line-bearing pressure 13.8.14.1 Rollers or rockers The maximum line-bearing pressure in newtons per millimetre (pounds per inch) on rollers or rockers shall be as follows: (a) For diameters less than 635 mm (25 in):

( p − 90 ) 2.76d

⎛ ( p − 13 000 ) 400d ⎞ ⎜ ⎟ 138 20 000 ⎝ ⎠ (b) For diameters of 635 to 3200 mm (25 to 125 in):

( p − 90 ) 2.22

d

138

⎛ ( p − 13 000 ) 2000 d ⎞ ⎜ ⎟ ⎜ ⎟ 20 000 ⎝ ⎠

where p

= the least of the values of the yield strength of the material in the roller, rocker, roller bed, or track, MPa (psi)

d

= diameter of roller or rocker, mm (in)

Where the rollers could be subjected to live load with the bridge closed, e.g., on a rim-bearing swing bridge, or for balance wheels subjected to wind loads, the maximum bearing pressures may be increased by 50%.

13.8.14.2 Segmental girders The maximum line-bearing pressure in newtons per millimetre (pounds per inch) on the treads of segmental girders rolling on flat surfaces for diameters of 3 m (10 ft) or more shall be as follows:

( p − 90) ( 2.10 + 0.55d ) 138

⎛ ( p − 13 000 ) (12 000 + 80d ) ⎞ ⎜ ⎟ 20 000 ⎝ ⎠

where p

= the lesser of the values of the yield strength of the steel in the segmental girder tread or track, MPa (psi)

d

= diameter of segmental girder, mm (in)

Those portions of the segmental girder and the track or tread that are in contact when the bridge is closed shall be designed for the sum of the dead load and live load (including dynamic load effects). Under this loading, the maximum line-bearing pressure may be increased by 50%.

13.8.15 Design of wire ropes 13.8.15.1 Bending formula For counterweight ropes, the maximum stress from the combined effect of direct loads and bending shall not exceed 0.22 of the ultimate stress of the rope specified in Table 13.13. The stress from the direct load shall not exceed 0.125 of the ultimate strength of the rope specified in Table 13.13. For operating ropes, the limits shall be 0.30 and 0.16, respectively. Where ropes are bent over sheaves or drums, the extreme fibre stress, f, in megapascals (pounds per square inch) shall be calculated as follows:

f = 0 .8

Edw cos2 L cos2 B D

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where E = modulus of elasticity of wire = 197 000 MPa (28 500 000 psi) dw

= diameter of largest individual wire, mm (in)

L

= angle of helical wire with axis of strand, radians (degrees)

B

= angle of helical strand with axis of rope, radians (degrees)

D

= pitch diameter of sheave or drum, mm (in)

Table 13.13 Ultimate stress and ultimate strength of steel wire rope of 6 × 19 classification and 6 × 25 filler construction (See Clauses 13.6.5.5.8, 13.6.5.5.9, 13.6.5.5.15, and 13.8.15.1.) Grade 1770

Grade 110/120

Rope diameter, d, mm

Approx. area of section Ultimate (= 0.4d 2), stress, mm2 MPa

Ultimate strength of entire rope, kN

12 14 16 18 20 22 24 26 28 32 36 40 44 48 52 56 60 64

57.6 78.4 102.4 129.6 160.0 193.6 230.4 270.4 313.6 409.6 518.4 640.0 774.4 921.6 1081.6 1254.4 1440.0 1638.4

84.0 114.0 149.0 189.0 234.0 283.0 336.0 395.0 458.0 600.0 755.0 935.0 1130.0 1350.0 1580.0 1830.0 2100.0 2390.0

1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460 1460

Rope diameter, d, in 1/2 5/8 3/4 7/8 1 1 1/8 1 1/4 1 3/8 1 1/2 1 5/8 1 3/4 1 7/8 2 2 1/8 2 1/4 2 3/8 2 1/2

Approx. area of section Ultimate (= 0.4d 2), stress, in2 psi

Ultimate strength of entire rope, lb

0.100 0.156 0.225 0.306 0.400 0.506 0.625 0.756 0.900 1.056 1.225 1.406 1.600 1.806 2.025 2.256 2.500

21 000 33 000 46 000 64 000 83 000 106 000 131 000 162 000 192 000 226 000 260 000 304 000 338 000 376 000 420 000 476 000 520 000

212 000 212 000 204 000 209 000 209 000 209 000 210 000 214 000 213 000 214 000 212 000 216 000 211 000 208 000 207 000 211 000 218 000

13.8.15.2 Sheaves and drums — Minimum diameters The minimum pitch diameters of sheaves and drums shall be as follows: (a) counterweight sheaves: not less than 72 times the rope diameter; (b) operating rope sheaves and drums: not less than 45 times the rope diameter; and (c) auxiliary counterweight sheaves: not less than 60 times the rope diameter.

13.8.15.3 Short arc contact Where operating ropes have an arc of contact with a deflector sheave of 45° or less, a minimum sheave diameter of 20 times the rope diameter may be used.

13.8.15.4 Limiting rope sizes The diameter of counterweight ropes shall normally be not less than 22 mm (0.875 in) and not greater than 64 mm (2.5 in). The use of diameters outside of this range shall require approval by the Engineer. The diameter of operating ropes shall be not less than 16 mm (0.625 in).

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13.8.15.5 Limiting rope deviations For counterweight ropes, the transverse deviation from a vertical plane through the centre of the sheave groove shall not exceed 1 in 40. The longitudinal deviation measured from a vertical plane tangent to the pitch diameter of the sheave shall not exceed 1 in 30. For operating ropes, the transverse deviation from a vertical or horizontal plane through the centre of the sheave or drum groove shall not exceed 1 in 30. The deviations specified in this Clause shall not be exceeded for any position of the moving span.

13.8.15.6 Initial tension of operating ropes The initial tension in each operating rope, I, measured in kilonewtons (pounds), shall be calculated as follows: I = (Ti /2) + P where Ti

= maximum operating tension in the rope (including unbalance, if any) kN (lb)

P

= minimum tension in the slack rope, kN (lb)

P should be not less than 0.1Ti .

13.8.16 Shafting 13.8.16.1 General Shafting shall be designed for combined bending and torsion loads in accordance with the following formulas:

S = 16

K M2 + T 2 πd 3

f = 16

K ⎡ M + M2 + T 2 ⎤ ⎦⎥ πd 3 ⎣⎢

where S

= shear stress, MPa (psi)

f

= extreme fibre stress in tension or compression, MPa (psi)

K

= the applicable impact factor specified in Clause 13.8.12.1

M

= simple bending moment calculated for the distance centre-to-centre of bearings, N•mm (in•lb)

T

= simple torsional moment, N•mm (in•lb)

d

= diameter of shaft at the section considered, mm (in)

Bending due to the tooth load of bevel gears shall be calculated as for a spur gear having a pitch diameter equal to the mean pitch diameter of the bevel gear. Shafting may be made of carbon or alloy steel forgings, or of structural steel bars, with the maximum allowable stresses specified in Table 13.11. Cold-rolled steel bars shall not be used for shafting of the main or auxiliary operating machinery. All gears or other components attached to shafts shall be located adjacent to bearings. The allowable stresses specified in Table 13.11 include the effects of keyways with a width of not more than 0.25 and a depth not more than 0.125 of the shaft diameter. In the absence of keyways, higher stresses may be used. For shafts supporting their own mass only, the unsupported length of the shaft between bearings shall not exceed 2353 d 2 mm or 80 3 d 2 in, where d is the diameter of the shaft in millimetres (inches).

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13.8.16.2 Speed of line shafts Line shafts connecting the machinery at the centre of the bridge with machinery at the ends shall be designed to run at a high speed, the speed reduction being made in the machinery at the ends.

13.8.16.3 Minimum size of shafts Shafts transmitting power for the operation of the bridge, and shafts 1200 mm (48 in) or more in length forming part of the operating machinery of bridge locks, shall be not less than 65 mm (2.5 in) in diameter.

13.8.16.4 Turning and balancing Shafting shall be turned as required for journals, gear seats, etc. When the speed exceeds 400 rpm, the shaft shall be turned full length. All gear shaft assemblies running over 600 rpm shall be dynamically balanced. Cold-rolled shafting need not be turned at journals.

13.8.16.5 Longitudinal movement Effective means for preventing longitudinal movement of shafting shall be provided (e.g., a split collar clamped in a cut groove or a substantial pin or bolt passing through a collar or through the hub of an attached part). Collars with set screws may be used only where there is no definite longitudinal force to be resisted.

13.8.16.6 Angular deflection Shafts shall be proportioned so that the angular deflection in degrees per metre (degrees per foot) of length under maximum loads will not exceed the following limits: (a) for all shafts: 50/d (0.6/d), where d is the shaft diameter in millimetres (inches); and (b) for more rigid drives where less spring is desirable, e.g., shafts driving end-lifting devices: 0.26 (0.08). When d exceeds 190 mm (7.5 in), Item (a) shall apply.

13.8.16.7 Alignment shafts and bearings Provision shall be made for field adjustment of the alignment of all shafts or bearings that cannot be assembled and fitted in the shop.

13.8.16.8 Change of section All shafts and trunnions shall have generous fillets where changes in section occur. Suitable stress concentration factors shall be used for unusual configurations.

13.8.16.9 Trunnions All trunnions more than 200 mm (8 in) in diameter shall have a hole whose diameter is about 0.2 times the outside diameter bored lengthwise through the centre.

13.8.17 Machinery fabrication and installation 13.8.17.1 Shaft keys 13.8.17.1.1 General All parts transmitting torsion to shafting shall be fastened thereto by keys. Keys shall not be wider than 0.25 times the diameter of the shaft. Their thickness shall be not more than 0.25 times the diameter of the shaft and their dimensions shall be such that the allowable stresses in shear and bearing will not be exceeded. If the keyed parts are also connected by a shrink or press fit, 25% of the transmitted torque may be assumed to be absorbed by this fit, and the keys shall be designed to take the remaining torque at the normal unit stresses specified in Clause 13.8.13.

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Keys shall be parallel faced, square or rectangular, and fitted into keyways cut into the hub and shaft. The keyway in the shaft and the key should have semi-circular ends. Keyways shall have filleted corners in accordance with ANSI B17.1.

13.8.17.1.2 Multiple keys When two keys are used to connect a rotating part to a shaft, they shall be placed at an angle of 120° to each other, except in cases where the keyed part is required to slide along the shaft, in which case two parallel keys shall be used, placed at an angle of 180° to each other. Each key shall be designed to carry 60% of the transmitted torque.

13.8.17.1.3 Trunnion keys For trunnions and similar parts that are designed for bending and bearing, the keys and keyways shall be proportioned simply to hold the trunnion from rotating. The force tending to cause rotation shall be taken as 0.2 times the load on the trunnion, acting at the circumference of the trunnion.

13.8.17.1.4 Locking Where necessary, keys shall be held by set screws or other effective means. In vertical shafts, bands clamped about the shaft, or other key-retaining devices, shall be placed below the key.

13.8.17.2 Shaft couplings All couplings shall be made of cast or forged steel. All couplings shall be standard manufactured flexible couplings and be placed close to bearings. Couplings between machinery components shall be gear type and provide angular or angular and offset misalignment capabilities as necessary. Couplings between prime movers and machinery components shall be flexible couplings transmitting the torque through metal parts and providing for both misalignment and shock. Couplings with non-metallic parts shall be used only for secondary mechanisms and shall function even after failure of the non-metallic elements. Rigid couplings may be used where self-aligning couplings are not required. All couplings shall be keyed to their shafts. Bolts in coupling housings shall be shrouded.

13.8.17.3 Bearings 13.8.17.3.1 Alignment When final alignment cannot be performed in the shop, supports for bearings shall provide for field alignment.

13.8.17.3.2 Material Steel shall be used for the following parts of all bearings unless otherwise specified by the Engineer: (a) the cap and base of plain bearings; and (b) the housing of anti-friction bearings. Cast iron housings may be used for light-duty bearings.

13.8.17.3.3 Bevel gear bearings The bases of the bearings for mating bevel gears shall be made in one solid piece. The hubs of bevel gears, worms, or worm gears shall bear against adjacent shaft bearings through suitable thrust collars or anti-friction thrust bearings.

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13.8.17.4 Plain bearings 13.8.17.4.1 Proportions The length of a bearing shall not be less than the diameter of the journal and should be 1.5 times that diameter except for counterweight sheaves, where the length shall not be more than 1.2 times the diameter.

13.8.17.4.2 Adjustment On all bearings, adjustment for height shall be provided in order to allow for wear. Adjustment of caps by means of laminated brass liners shall be provided.

13.8.17.4.3 Bushings Bearings shall have bronze bushings unless otherwise approved by the Engineer. Alloys for various types of service shall be in accordance with Table 13.12. The bronze linings shall be effectively locked against rotation. The force tending to cause rotation shall be taken as 0.06 times the load on the bearing, acting at the outer radius of the lining. The inside corners of the bushings shall be rounded or chamfered, except for a distance of 10 mm from any joint.

13.8.17.4.4 Journal bearings Journal bearings shall have split housings. The cap shall be recessed into the base and fastened by bolts, with the heads recessed into the base. Nuts shall be hexagonal and lock nuts shall be provided. Both heads and nuts shall bear on finished bosses or spot-faced seats. Bearings shall be designed to facilitate cleaning.

13.8.17.4.5 Step bearings The bearing ends of vertical shafts running in step bearings shall be of hardened steel and shall run on bronze discs.

13.8.17.5 Anti-friction bearings 13.8.17.5.1 General Anti-friction bearings may be used for applications where good commercial practice would indicate their suitability and economy. Anti-friction bearings shall be sized for an American Bearing Manufacturers Association B-10 life of 40 000 h under design running conditions. Anti-friction bearings mounted in pillow blocks shall be self-aligning and shall have seals suitable for the conditions under which they operate. Housings shall be steel and may be split on the centreline. Bases shall be solid and shall be drilled for mounting bolts at assembly. Positive alignment shall be provided between the cap and the base on split housings. The alignment system shall be adequate for the design bearing loads.

13.8.17.5.2 Thrust bearings The bearing ends of vertical shafts shall run in ball or roller thrust bearings or in radial bearings of types capable of carrying both radial and thrust loads.

13.8.17.5.3 Trunnion bearings Where roller bearings are used to support the trunnions of counterweight sheaves of vertical lift bridges and similar shafts carrying heavy loads, they shall receive special design consideration in establishing the most suitable size and type. Only manufacturers who have experience in producing bearings for this type of service shall be considered.

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13.8.17.6 Gearing 13.8.17.6.1 Material Power-driven gears shall be made of steel.

13.8.17.6.2 Tooth type Power-driven gears shall have straight spur teeth of full depth. They shall be of the involute type, with a pressure angle of 20°, and be machine cut.

13.8.17.6.3 Rack and pinion gearing For rack and pinion gearing, stub teeth or special forms of teeth designed for greater strength may be used. The circular pitch for rack and main pinion gearing shall not be less than 40 mm. Pinions shall have at least 15 teeth for standard full-depth teeth. Main pinions shall have at least 17 teeth. The pitch line shall be inscribed on both ends of all cut teeth for racks, gears, and pinions. The backs or sides of racks that bear on metal surfaces and surfaces in contact with them shall be finished.

13.8.17.6.4 Enclosed gear speed reducers For enclosed gear speed reducers, the following shall apply: (a) Speed reducers shall be models from one manufacturer unless otherwise approved by the Engineer. The reducers shall have the gear ratios, dimensions, construction details, and American Gear Manufacturers Association (AGMA) ratings as shown on the drawings. Ratings shall be based on a service factor of 1.0. (b) The AGMA strength rating shall be based on a torque equal to 300% of full-load motor torque. Gears shall have helical or herringbone teeth, bearings shall be of the anti-friction type, and housings shall be welded steel plate or steel castings. The insides of the housings shall be sandblast-cleaned before assembly and protected from rusting. Exact ratios shall be furnished where specified. (c) Each unit shall have a means for filling and draining the case, an inspection cover, and a dipstick and sight glass to show the oil level. Sight glasses shall be of rugged construction and protected against breakage. Drains shall have shut-off valves to minimize spillage. Each unit shall have a moisture trap breather. (d) Lubrication of the gears and bearings shall be automatic when the unit is in operation. (e) If a pressurized lubrication system is required for the reducer, a backup lubrication system shall be provided. The backup system shall operate whenever the reducer is operating. (f) A remote sensor shall be provided to indicate when a pressurized lubrication system malfunction occurs. (g) Reducers shall be manufactured in accordance with AGMA requirements and shall have nameplates indicating the rated horsepower, ratio, speed, service factor, and AGMA symbols. (h) Reducer bases shall extend sufficiently past the body of the reducers to allow for mounting bolt hole reaming and bolt installation from above the unit. (i) Inspection covers shall be sized and located to allow for inspection of all gears and bearings. (j) Gearing shall conform to AGMA Quality No. 8 or higher. (k) The reducer design calculations and shop drawings showing each gear box component shall be submitted to the Engineer before construction of the unit.

13.8.17.6.5 Details of design of teeth The face width of cut spur gears shall not exceed three times the circular pitch. The face width of bevel gears shall not exceed 0.33 times the slant height of the pitch cone.

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13.8.17.6.6 Permissible loads on gear teeth In the design of spur, bevel, helical, and herringbone gears, the full load shall be taken as applied to one tooth. For spur gears, the permissible load on teeth shall be determined by the Lewis equations, including the velocity factors.

13.8.17.6.7 Permissible stresses in gear teeth The permissible stresses for gear teeth shall be as specified in Table 13.14.

13.8.17.6.8 Teeth strength factors Allowable stresses for racks and pinions and other gear sets not mounted in a common frame shall be reduced 20% from the values listed in Table 13.14.

13.8.17.6.9 Worm gearing Except for the operation of wedges, span locks, and other secondary mechanisms, worm gearing shall not be used to transmit power unless approved by the Engineer.

13.8.17.7 Welded parts 13.8.17.7.1 Machinery supports Machinery bases, support frames, chassis, platforms, seats, brackets, and similar items may be of welded construction.

13.8.17.7.2 Welded components Primary machinery components, e.g., counterweight sheaves, rope drums, gears, gear cases, and bearing housings, may be of welded construction from structural steel.

Table 13.14 Permissible stresses in gear teeth (See Clauses 13.8.17.6.7 and 13.8.17.6.8.) ASTM Specification

Permissible stress for cut teeth, MPa (psi)

Cast steel

A 27M, Grade 480-250 A 27, Grade 70-36

110 (16 000)

Forged carbon steel

A 668/A 668M, Class C A 668/A 668M, Class D

138 (20 000) 155 (22 500)

Forged alloy steel

A 668/A 668M, Class G and higher

60% of yield strength but not more than 33% of ultimate tensile strength

Cast bronze

B 22, Alloy 905

62 (9000)

Cast bronze (high strength)

B 22, Alloy 863

138 (20 000)

Material

13.8.17.7.3 Design of welded connections The design of welded connections shall be in accordance with Section 10. To allow for impact, the static design load shall be increased by 100%. The stress range for welds on machinery components, bases, support frames, etc. that are subject to vibrational or shock loads shall not exceed the constant amplitude threshold stress range specified in Table 10.4 for the detail category involved.

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Structures or components that are to be welded shall be designed so that distortion or residual stresses resulting from welding operations are minimized. In cases of complicated weldments requiring large deposits of weld metal, the welding procedure shall be clearly defined and carefully controlled in practice. When necessary, weldments shall be stress-relieved or peened. Fracture control in accordance with Clause 10.23 shall be considered during material selection and structural design.

13.8.17.7.4 Welding All welding shall be in accordance with Clause 10.24.

13.8.17.8 Bolts and nuts Bolts and nuts shall comply with the following requirements: (a) Bolts for connecting machinery parts to each other or to steel supporting members shall be one of the following types: (i) finished high-strength bolts; (ii) turned bolts, turned cap screws, and turned studs; and (iii) high-strength turned bolts, turned cap screws, and turned studs. (b) Finished high-strength bolts shall meet the requirements of ASTM A 449. High-strength bolts shall have finished bodies and regular hexagonal heads. Holes for high-strength bolts shall be not more than 0.25 mm (0.01 in) larger than the actual diameter of individual bolts, and shall be drilled to match the tolerances for each bolt. The clearance shall be checked with 0.28 mm (0.011 in) wire. The hole shall be considered too large if the wire can be inserted into the hole together with the bolt. (c) Turned bolts, turned cap screws, and turned studs shall have turned shanks and cut threads. Turned bolts shall have semi-finished, washer-faced, hexagonal heads and nuts. Turned cap screws shall have finished, washer-faced, hexagonal heads. All finished shanks of turned fasteners shall be 1.6 mm (0.063 in) larger in diameter than the diameter of the thread, which shall determine the head and nut dimensions. The shanks of all turned fasteners shall have Class LT1 fit in the finished holes in accordance with ASME B4.1. The material for the turned shank fasteners shall meet the requirements of ASTM F 568M, Class 4.6 (ASTM A 307, Grade A). (d) High-strength turned bolts, turned cap screws, and turned stud details shall be as specified in Item (c), except that the material shall meet the requirements of ASTM A 449. (e) Elements connected by bolts shall be drilled or reamed assembled to ensure accurate alignment of the hole and accurate fit over the entire length of the bolt within the specified limit. (f) The dimensions of all bolt heads, nuts, castle nuts, and hexagonal head cap screws shall be in accordance with the applicable ASME Standard (B18.2 series). (g) Heads and nuts for turned bolts, screws, and studs shall be heavy series. (h) ASTM A 449 bolts shall be tightened to at least 70% of their required minimum tensile strength. (i) The dimensions of socket-head cap screws, socket flathead cap screws, and socket-set screws shall be in accordance with ASME B18.3. The screws shall be made of heat-treated, cadmium-plated alloy steel and furnished with a self-locking nylon pellet embedded in the threaded section. Unless otherwise called for on the drawings or specified in this Section, set screws shall be of the headless safety type, shall have threads of the coarse thread series, and shall have cup points. Set screws shall not be used to transmit torsion or as fastenings or stops for any equipment that contributes to the stability or operation of the bridge. (j) Threads for bolts, nuts, and cap screws shall be of the coarse thread series and shall have a Class 2 tolerance for bolts and nuts or a Class 2A tolerance for bolts and Class 2B tolerance for nuts in accordance with ASME B1.10. (k) Bolt holes through unfinished surfaces shall be spotfaced for the head, nut, and washer, square with the axis of the hole. (l) Unless otherwise called for on the drawings, all bolt holes in machinery parts or connecting such parts to the supporting steelwork shall be subdrilled at least 0.8 mm (0.031 in) smaller in diameter than the bolt diameter. The steelwork shall be subdrilled after the machinery is correctly and finally assembled and aligned, and then the holes shall be reamed for the proper fit with the bolts.

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(m) Holes in shims and fills for machinery parts shall be reamed or drilled to the same tolerances as the connected parts at final assembly. (n) Positive locks of a type approved by the Engineer shall be furnished for all nuts, except those of ASTM A 449 bolts. Double nuts shall be used for all connections requiring occasional opening or adjustment. If lock washers are used for securing, they shall be made of tempered steel and shall conform to Society of Automotive Engineers (SAE) regular dimensions. The material shall meet the SAE tests for temper and toughness. (o) High-strength bolts shall be installed with a hardened plain washer in accordance with ASTM F 436 at each end. (p) Wherever possible, high-strength bolts connecting machinery parts to structural parts or other machinery parts shall be inserted through the thinner element into the thicker element. (q) Cotters shall conform to SAE standard dimensions and shall be made of half-round stainless steel wire meeting the requirements of ASTM A 276, Type 316. (r) Anchor bolts connecting machinery parts to masonry shall be of ASTM F 568M, Class 4.6 (ASTM A 307, Grade A) material, hot-dipped galvanized in accordance with ASTM A 153/A 153M unless otherwise specified by the designer. Bolts shall be as shown on the structural drawings. Anchor bolts for new construction shall be cast-in-place and not drilled. The designer shall specify the material and loading requirements for the given design condition. When anchor bolts connect a mechanical component directly to the concrete, there shall be a filler material in the annular area between the bolt and the bolt hole in the machinery component. The filler material may be a non-shrink grout, babbitt metal, or zinc. (s) Bolts and nuts shall be North American manufacture and shall be clearly marked with the manufacturer’s designation unless otherwise Approved.

13.8.17.9 Wrenches A set of wrenches to fit those bolts and nuts that (a) are 30 mm or larger; (b) are actually used on the machinery; and (c) might require tightening, adjustment, or dismantling shall be furnished by the supplier of the machinery.

13.8.17.10 Set screws Set screws shall not be used for transmitting torsion loads. They may be used for holding light parts such as keys in place.

13.8.17.11 Dust covers Dust covers shall be provided to protect sliding and rotating surfaces and prevent dirt from mixing with the lubricant.

13.8.17.12 Drain holes Proper provision shall be made for draining at places where water is likely to collect.

13.8.17.13 Cams Cams and similar devices shall not normally be used for transmitting power by line or point contact.

13.8.18 Lubrication A combined diagram and chart covering all machinery parts that require lubrication, with recommendations or the type of lubricant to be used for each part and the frequency of lubrication, shall be included in the operating and maintenance manual. Non-fading prints of the diagram and chart shall be framed under glass near each machinery area. Provision shall be made for effective lubrication of all sliding surfaces and of ball and roller bearings. Lubricating devices shall be easily accessible.

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Grease grooves shall be machine cut in the bushings of the bearings. Grooves shall be straight for large bearings, number at least three, and spaced so that the entire surface will be swept by lubricant in one cycle of opening or closing the bridge. Grooves in the shape of a figure eight shall be acceptable for shafts making more than one revolution per opening or closing cycle. Grooves shall be smoothly transitioned into the bushings and shall be of such a size that an 8 mm diameter wire will lie wholly within the groove. Grooves shall have inlet and outlet ports to facilitate cleaning and purging. A high-pressure system of lubrication shall be provided for journal bearings and sliding surfaces (where practicable). Where lubrication points are not readily reached, the fittings shall be made accessible by extension pipes. Grooves shall be provided where necessary for the proper distribution of the lubricant. Disc bearings shall be provided with oil bath lubrication. Where anti-friction gear cases are used, the gearing should be oil bath lubricated and the bearings splash lubricated. Where plain bearing gear cases are used, the gearing should be oil bath lubricated and the journals grease lubricated. Where bearings are small, the unit-bearing pressures are low, and the motion is slow and intermittent, self-lubricating bushings may be used. These bushings shall be of a type that will not be injured by the application of oil and shall have protected oil holes for emergency use. Self-lubricating bushings shall not be used for the main machinery. The sliding surfaces of span guides, locks, etc. shall be hand lubricated with a suitable grease. Two hand-operated grease guns, including adapters, shall be provided as necessary to service all lubrication fittings. For special devices, the manufacturer’s recommendations for lubrication shall be followed.

13.8.19 Power equipment 13.8.19.1 Tests of machines Machines that are of the usual manufactured types, e.g., gasoline or diesel engines, electric motors, oil motors, pumps, and air compressors, shall be tested for the specified performance requirements to the satisfaction of the Engineer and shall be guaranteed by the supplier to fulfill these requirements for one year. Note: “Specified performance requirements” can mean requirements specified in this Code, by the Owner, or in the contract, as applicable.

13.8.19.2 Brakes 13.8.19.2.1 General Brakes shall be provided in accordance with Clause 13.8.7.

13.8.19.2.2 Electrically operated brakes Motor brakes for the main motors shall be thruster- or motor-operated spring-set shoe brakes with a torque and a time rating that meets the load requirements of Clause 13.8.7. Machinery brakes for the main machinery shall be thruster- or motor-operated spring-set shoe brakes that are continuously rated, with a torque and a time rating that meets the load requirements of Clause 13.8.7. Brakes shall be electrically interlocked with the main motors to prevent motor operation if the brakes are applied. Brakes shall be arranged for hand release. Interlocking switches shall be provided to prevent electric power operation when the brakes are in the hand-released position. Enclosing covers that are weatherproof and easily removable shall be supplied if the brakes are not in a machinery enclosure. Electrically operated brakes located on the moving leaf of a bascule bridge shall be spring set and function in any position of bridge rotation.

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13.8.19.2.3 Mechanically operated brakes 13.8.19.2.3.1 General Mechanically operated brakes should be of the shoe type. If the main function of these brakes is to stop and hold the moving span in any position, e.g., for machinery brake usage, they shall be arranged so that the brake is applied by a mass or spring and released by hand or foot.

13.8.19.2.3.2 Air brakes Air brakes shall be controlled from the operator’s house.

13.8.19.2.3.3 Hydraulic brakes Hydraulic brakes shall be operated by a foot pedal in the operator’s house.

13.8.19.2.3.4 Mechanically operated hand or foot brakes If the brakes are to be mechanically operated by hand or foot, the operating lever in the operator’s house shall be suitably connected to the brake mechanism at the brake wheel by levers and connecting rods.

13.8.19.2.3.5 Material for brake wheels Brake wheels should be made from ductile cast iron or another material with characteristics suitable to the application. Ordinary cast iron shall not be used for brake wheels.

13.8.19.3 Internal combustion power equipment 13.8.19.3.1 Gasoline or diesel electric power For bridge locations where adequate electric power is not available, electric generator sets driven by diesel or gasoline engines may be provided. Such power units shall be of the type currently used for commercial industrial service.

13.8.19.3.2 Gasoline or diesel engine power 13.8.19.3.2.1 General Gasoline or diesel engines, where used, shall be of the industrial, automotive, or marine type; only substantial or heavy-duty models shall be used. The operational speed shall be limited to 1800 rpm and should be not more than 1400 rpm. Engines should have at least four cylinders, shall be equipped with a suitable speed governor, and shall be effectively water cooled by a radiator and fan. An exhaust pipe that discharges outside the engine room and is fitted with an industrial-type muffler and moisture trap shall be provided for each engine. The engines shall be tested by the manufacturer at its plant to prove that they will develop the specified torque rating.

13.8.19.3.2.2 Clutch and overload protection A friction clutch of a design approved by the Engineer shall be provided between the engine and the driven machinery. It shall be capable of being gradually applied and shall be designed so that it will slip at a predetermined torque to protect either the engine or the driven machinery from overload damage at all times and under all conditions of operation. If it is not practicable to supply a clutch with these built-in safety features, an additional device of a design approved by the Engineer, e.g., a friction or hydraulic coupling, shall be installed between the engine and the driven machinery to provide the required overload protection.

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13.8.19.3.2.3 Reversing gear Engines shall be equipped with a reversing gear unit mounted on a common frame and shall be designed so that the bridge drive machinery can be run in either direction with the engine running continuously. This reversing gear shall be capable of transmitting the full torque of the engine in either direction.

13.8.19.3.2.4 Control board A small control board for mounting the throttle and choke controls, ignition switch, starter button, oil and temperature gauge, and any other operational equipment shall be provided at the engine and should be mounted integrally with it.

13.8.19.3.2.5 Arrangement of controls The controls for operating the bridge under internal combustion power shall be positioned so that one operator can conveniently and quickly perform, from one location, all functions necessary for the operation of the bridge, e.g., the starting and stopping of the engine and the release and resetting of electric brakes where emergency electric power is available. The operator shall also be able to operate any drive clutch, reversing clutch, foot brake, or other vital device and be able to see the engine control board and the span position indicator (if any).

13.8.19.3.2.6 Fuel tanks Fuel tanks shall be made of corrosion-resistant metal. When gasoline is used for fuel, the fuel tanks shall be located outside of the machinery house and be protected from the direct rays of the sun. If the engine is the primary power unit, the fuel tanks shall have sufficient capacity for 30 d normal operation of the bridge. If the engine is used for auxiliary power only, the fuel tanks shall have a minimum capacity of 76 L. Tanks shall be equipped with an automatic gauge to indicate the quantity of fuel on hand, a sump, and a drain cock. All pipes and fittings connecting the tanks to the engine shall be made of copper or brass.

13.8.19.3.2.7 Spare parts Spare parts for the ignition system and other necessary spares shall be furnished in accordance with a list specified by the Engineer.

13.8.20 Quality of work 13.8.20.1 General The machinery shall be manufactured, finished, assembled, and adjusted in accordance with best industry practice. Machinery components in contact with each other, or in contact with machinery supports, shall be machined to provide true contact surfaces. Surfaces that are in moving contact with other surfaces shall be machined true to dimension and with the grade of finish specified on the drawings. Castings shall be clean and all fins and other irregularities shall be removed. Unfinished edges of flanges and ribs shall have rounded corners. All inside angles shall have suitable fillets. Drainage holes of suitable sizes shall be provided where necessary to prevent collection of water.

13.8.20.2 Fits and tolerances The limits of accuracy for machining the work and the tolerances on all metal fits shall be shown on the shop drawings. Fits and tolerances shall be in accordance with CSA B97.3. The following six classes of fits, selected from CSA B97.3, shall be used in movable bridge applications: (a) FN1 (light drive fit); (b) FN2 (medium drive fit); (c) LC1 (locational clearance fit no. 1); (d) LC4 (locational clearance fit no. 4); (e) LT1 (locational transition fit no. 1); and (f) RC6 (medium running fit). November 2006

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These six classes shall be applied in accordance with Table 13.15. The machined work, where decimal dimensions are given with a tolerance indicated, shall be within the limits of this tolerance. The size that will obtain the most satisfactory mating of parts will be halfway between these limits, and this result shall be sought whenever practicable. The standard fits listed in this Clause apply only where both fitting parts are machined.

Table 13.15 Fits and finishes (See Clauses 13.8.20.2 and 13.8.20.3.) Finish Part(s)

Fit

Micro-inches Microns

Machinery base on steel Machinery base on concrete Shaft journal Journal bushing Split bushing in base Solid bushing in base (up to 6.4 mm wall) Solid bushing in base (over 6.4 mm wall) Hubs on shafts (up to 50.8 mm bore) Hubs on shafts (over 50.8 mm bore) Hubs on main trunnions Turned bolts in finished holes Sliding bearings Keys and keyways Machinery parts in fixed contact Teeth of open spur gears Circular pitch under 25 mm Circular pitch 25–44 mm Circular pitch over 44 mm

— RC6 RC6 LC1 FN1 FN2 FN2 FN2 FN2 LT1 RC6 LC4 — — —

250 500 8 16 125 63 63 32 63 32 63 32 6 125

6.3 12.7 0.2 0.4 3.2 1.6 1.6 0.8 1.6 0.8 1.6 0.8 1.6 3.2

32 63 125

0.8 1.6 3.2

Note: The fits for cylindrical parts specified in this Table shall also apply to the major dimension of non-cylindrical parts.

13.8.20.3 Surface finishes The American National Standards Institute (ANSI) system of surface finishes shall be used for indicating the various degrees of roughness allowed for machine-finished surfaces. Such finishes shall be in accordance with Table 13.15.

13.9 Hydraulic system design Because movable bridges at many locations in Canada do not operate in winter, necessitating a close-down and start-up operation, the designer of the hydraulic system shall consider the effect of this inactivity on maintenance requirements for the system. The designer shall also consider the need to prevent contamination of the environment by the hydraulic fluid. The detailed design requirements for hydraulic design shall be as specified in Article 6.5.37 of Chapter 15 of the AREMA Manual for Railway Engineering, subject to the following: (a) any reference to “Company” in the Manual shall be taken to mean “Owner”; and (b) where the Manual refers to parts of the Manual other than Article 6.5.37 of Chapter 15, these shall be taken to refer to the applicable clauses of this Code.

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13.10 Electrical system design 13.10.1 General The requirements specified in Clause 13.10 are based on the use of either dc or 60 Hz ac motors. Movable bridges should be operated by dc motors using variable-voltage control or adjustable-voltage control, by ac squirrel-cage induction motors using variable-voltage control or variable-frequency control, or by ac wound-rotor induction motors with the appropriate control system. The use of other motors or motor-controller methods shall be in accordance with the requirements specified by the Owner. For the operation of a vertical lift bridge, the requirements of Clause 13.10 are based on the use of one hoisting machine to operate the bridge or on the use of two hoisting machines mechanically connected. Special requirements are specified for tower-drive vertical lift bridges that use independent hoisting machines at the ends of the span operated by ac or dc motors electrically connected by synchronizing motors or synchronizing controls to maintain the bridge in level position during operation. When required by the Engineer, such independent hoisting machines shall maintain the span in level position during operation by means of special synchronizing controls and the requirements of Clause 13.10 shall be as subject to such modifications as are required by the Engineer.

13.10.2 Canadian Electrical Code, Part I The construction and installation of all electrical materials and devices shall be in accordance with the Canadian Electrical Code, Part I, and local ordinances, except as otherwise specified in Clauses 13.10.3 to 13.10.50.

13.10.3 General requirements for electrical installation The drawings shall indicate the electric power service that is available and the location of the point at which such service shall be obtained. The contractor shall provide the electrical installation complete from this service point, including all equipment, wiring, and cables, except as specified by the Engineer. The electrical equipment shall comply with the Standards of the following organization, as applicable: CSA, the Electrical and Electronic Manufacturers Association of Canada (EEMAC), the Institute of Electrical and Electronics Engineers (IEEE), the National Electrical Manufacturers Association (NEMA). The voltage characteristics of the power supply shall be determined by the Owner. Where necessary, suitable stabilization equipment shall be included in the system. Total voltage drops shall not exceed 5% at rated load within the electrical installation. The contractor shall provide all grounding devices required for the electrical equipment and service. To prevent deterioration due to corrosion of parts of the electrical installation other than electrical apparatus, all bolts, nuts, studs, pins, screws, terminals, springs, and similar fastenings and fittings shall be, where practicable, of a corrosion-resisting material, e.g., stainless steel or bronze, approved by the Engineer or of a material treated in a manner approved by the Engineer to render it adequately resistant to corrosion. Hot-dip galvanizing of materials in compliance with CSA Standards for such materials shall be considered an approved treatment. Corrosion-prevention treatment of electrical equipment shall be as specified by the Engineer to suit the conditions of exposure. All metal parts of the electrical equipment, including all conduits not furnished with a fused coating of polyvinylchloride, shall be painted as specified by the Engineer for structural steel. For conduits and similar parts where it is not practicable or convenient to apply paint in the shop, the shop coat may be applied in the field and followed by the required field coats. The contractor shall take insulation resistance readings on all installed circuits (with the electrical equipment disconnected) and shall furnish a complete record of the results. These circuits should include connected motors when tested. Circuits, feeders, and equipment up to 350 V shall be tested with a 500 V instrument. Circuits, feeders, and equipment from 350 to 600 V shall be tested with a 1000 V instrument. Resistance to grounding devices shall be checked before energizing. At least one megohm shall be registered. Defective circuits shall be replaced. Requirements for emergency operation of power-operated bridges and for standby power for electrically operated bridges shall be as specified in Clause 13.8.

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All electrical installations shall incorporate seismic restraints in accordance with applicable regional or local codes.

13.10.4 Working drawings 13.10.4.1 In addition to furnishing the data required by Clause 13.13, the contractor shall prepare and furnish complete working drawings for the electrical system. In these drawings the distance between adjacent lines and symbols of elements shall not be less than 10 mm. The number of required sets of drawings shall be specified by the Owner. Only drawings approved by the Engineer shall be used for construction. The tracings shall be revised to show the work as constructed and shall then become the property of the Owner.

13.10.4.2 Working drawings shall include the following: (a) Wiring interconnection diagrams that provide termination identification of wires and cables, sizes and numbers of wires and cables, and the make and capacity of all apparatus, including the ratings of impedances. Schematic diagrams shall include two- or three-line power and control diagrams showing the connection schemes, including detailed equipment and control schematic diagrams, which shall include the control panels and console. The number of each wire and the designation for each electrical device or piece of equipment shall be shown on the control schematic diagram. This device designations shall be used to identify each piece of equipment on the assembly and installation drawings, which shall show locations to scale of all external and internal components, including terminal blocks for the control panels, terminal boxes, and control console. (b) One-line diagrams showing the complete power and distribution system. (c) Control block diagrams for complex systems, showing the control components in block form and the interconnection of blocks and direction of signal flow. (d) Conduit drawings showing the routing and size of each conduit, the number and size of each wire in each conduit, and the location and method of support of all conduits, ducts, boxes, and expansion fittings. Each conduit shall be given an individual conduit designation. (e) Installation drawings giving the location of all cables, conduits, control panels, control consoles, resistances, lamps, switches, and other apparatus. (f) Sectional drawings of all cables, showing component parts, their dimensions, and the material used. (g) Drawings showing the general construction and dimensions of the control console and all control panels and the arrangement of all equipment thereon. (h) Certified dimension prints of all electrical equipment. (i) Detailed construction drawings of all boxes, troughs, ducts, and raceways other than conduit. (j) Detailed construction drawings of warning gates and barrier gates, navigation lights, and audible signalling devices. (k) Curves for each span-driving motor, showing the variation in motor speed and motor currents with output torque, and within the torque intervals determined by test in accordance with Clause 13.10.5, for each power point on the controller. The requirements of Items (a) and (b) for working drawings may be partially fulfilled by use of a suitably coordinated conduit and cable schedule.

13.10.5 Motor and generator tests One span-driving motor of each size or type used shall be subjected to a complete test in accordance with CSA C22.2 No. 100 or ANSI/NEMA MG-1. At the option of the Owner, certified test data of a motor of identical design may be accepted in lieu of tests of the actual motors. For ac motors the tests shall also include the determination of the variation in speed and motor currents with motor torques from zero to the maximum designed torque for the drive system. Where required by the Engineer, the speed-current-torque curve shall also be determined for overhauling torque, including

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the effects of the motor control equipment. In addition, for wound-rotor motors the speed-current-torque relationship shall be determined with a rotor-shorted condition. All dc motors shall also be tested to determine the speed-current-torque relationship for each power point on the controller, from an overhauling torque of 100% of full load to a driving torque of 200% of full load. Unless otherwise specified by the Engineer, all motors except span-driving motors tested to CSA C22.2 No.100 or ANSI/NEMA MG-1 requirements shall be subjected to a short commercial test. If the results indicate characteristics differing materially from those of the completely tested motor, the contractor shall make the necessary alterations and run complete tests to demonstrate the final characteristics. The motors in tower-drive vertical bridges with synchronizing motors shall be subject to the test requirements for span-driving motors, except that where the synchronizing motors are of the same size and type as the span-driving motors, only the short commercial test shall be required. Each generator shall be subjected to a short commercial test. Except as otherwise approved by the Owner, all motor and generator tests shall be made in the presence of an inspector designated by the Owner. The contractor shall furnish six certified copies of each test report.

13.10.6 Motors — General requirements The following requirements shall be met: (a) Motors shall be of the totally enclosed type unless otherwise specified by the Engineer. (b) Motors subjected to atmospheric conditions shall be totally enclosed and non-ventilated or totally enclosed and fan cooled. (c) Motors installed in weather-protected houses may be drip-proof or of the protected type. (d) Unless otherwise specified by the Engineer, motor windings shall be impregnated with a moisture-resisting compound in order to increase their resistance to moisture, and span-drive motors shall have embedded winding temperature-sensitive devices. (e) A drain hole shall be provided in the bottom of the motor frame and, where feasible, heaters shall be incorporated. A seal-type plug and sealed entrance for the heaters shall be required for motors subjected to atmospheric conditions. Heaters shall be thermostatically controlled and shall be de-energized when the motor is operating. (f) Motors whose frames tilt during the operation of the bridge shall have ball or roller bearings arranged with provisions for flushing. (g) Span motors shall be capable of stalled operation for 2 min with the motor control equipment functioning normally for seating torque. (h) Primary and secondary conduit boxes for span-driving motors shall be split cast and fully gasketed. All dc motors shall be series, compound, or shunt wound, as determined by the performance specified, and shall have commutating poles. Motors for dynamic or regenerative braking shall perform their function within the allowable temperature rise. Span-driving motors shall comply with ANSI/NEMA MG-1. All ac motors shall be induction motors that are suitable for the specified service characteristics and comply with CSA C22.2 No. 100 or ANSI/NEMA MG-1. Preferably, all motors shall be of the wound-rotor type for ac variable-voltage silicon controlled rectifier (SCR) drives or of the squirrel cage type for ac variable-frequency drives.

13.10.7 Motor torque for span operation The locked rotor and breakdown torques for ac motors shall be those specified by CSA C22.2 No. 100 or ANSI/NEMA MG-1. Motor torques shall be as follows: (a) For a one-motor installation, not more than 125% of the full-load motor torque shall be required to produce the maximum required bridge starting torque. The maximum torque peaks that occur when the bridge is accelerated to the required speed using the specified bridge control should not exceed 180% of the rated full-load motor torque. (b) For a two-motor installation with no provision for operating the bridge with a single motor, the two motors jointly shall meet the requirements specified in Item (a). November 2006

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(c) For each motor in a two-motor installation with provision for operating the bridge with a single motor in not more than 1.5 times the opening time specified in Clause 13.5.8, not more than 150% of the full-load motor torque shall be required to produce the maximum required bridge starting torque. The maximum bridge-starting torque shall be determined in accordance with Clause 13.8.9.

13.10.8 Motor temperature, insulation, and service factor All ac motors shall have Class B or better insulation, 1.15 service factors, and ambient temperature ratings of 40 °C unless otherwise specified by the Engineer. All dc motors shall have Class F insulation, 1.0 service factors, and ambient temperature ratings of 40 °C. Note: Classes of insulation are described in CSA C22.2 No. 100 and ANSI/NEMA MG-1.

13.10.9 Number of motors When the total power necessary at the motor shaft to move the bridge under Case A of Clause 13.8.5.2 at the required speed exceeds 37 kW (50 hp), the use of two similar span-driving motors, with provision for operation of the bridge by one motor, shall be considered, taking into account the importance of both the bridge and the waterway. Warning gates, bridge locks, and the end and centre lifting devices of a swing span should be operated by one or more motors separate from and independent of the span-drive motors.

13.10.10 Synchronizing motors for tower-drive vertical lift bridges Where synchronizing motors are used on a tower-drive vertical lift bridge to maintain the bridge in level position during operation, the total full-load rated torque of these motors on each tower shall not be less than 50% of the total full-load rated torque of the span-drive motors on each tower, and consideration shall be given to increasing this to 100% where practicable.

13.10.11 Speed of motors The speed of span-driving motors shall not exceed 900 rpm. The speed of motors that operate bridge locks and wedges shall not exceed 1200 rpm. The speed of gear motors of 7.5 kW (10 hp) or less, fractional horsepower motors, motors driving hydraulic pumps, and motor-generator sets shall not exceed 1800 rpm.

13.10.12 Gear motors Gear motors should have an extension of the high-speed shaft to allow hand operation. Gears shall be lubricated by immersion in the lubricant and effective seals shall be provided to prevent the lubricant from reaching the motor windings. Gear motors shall have at least a Class II rating as defined by AGMA and shall carry an AGMA nameplate stating the kilowatts (horsepower), service rating, and service factor.

13.10.13 Engine-generator sets 13.10.13.1 General Engine-generator sets, whether for primary or emergency power, shall consist of an internal combustion engine and an electric generator direct connected and mounted on a common base. Separate units may be provided for supplying power for span operation and for auxiliary services such as lights and signals. Where used as an emergency power source, the lighting generator unit shall start automatically on failure of the normal power. The span-operating power unit shall be started manually by a remote control switch. Engines shall meet the applicable requirements of Clauses 13.8 and 13.10.13.2. They shall develop adequate power to supply the maximum load, including the motor-starting load, while maintaining speed within the specified range. Consideration shall be given to the special requirements of non-linear and harmonic-producing loads.

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13.10.13.2 Instruments and controls Engine instruments and controls shall be mounted in a cabinet on the unit and shall include gauges indicating water temperature, oil pressure and temperature, and vacuum (for diesel engines); a throttle control; a start/stop switch for manual control; a manual emergency shutdown; indicating lights for low oil pressure, high water temperature, overspeed, and overcrank; and an alarm contact for sounding a remote alarm in case of high water temperature, low lubricating oil pressure, or failure to start after four cranking cycles.

13.10.13.3 Engine governor The engine governor shall provide 3 to 5% speed regulation from no load to maximum load.

13.10.13.4 Generator and exciter The generator power characteristics shall be capable of supplying the maximum load, including the motor-starting load, at suitable power characteristics, with a regulated voltage drop within the limits specified by the Engineer. It shall have a continuous rating with Class B or better insulation over 40 °C ambient, be of drip-proof construction, and comply with applicable CSA, ANSI, IEEE, and NEMA Standards. The exciter shall be of the direct-connected brushless type and sized to furnish 10% more excitation than is required at full generator-operating load. When the generator supplies non-linear loads, the exciter shall be of the permanent magnet type.

13.10.13.5 Starting system An automatic starting system, complete with suitable batteries and automatic charging, shall be provided and shall have (a) a positive shift gear-engaging starter, 12 V dc; (b) a cranking limiter to provide four cranking cycles of 10 s duration, each separated by 5 s rest; (c) a storage battery with sufficient capacity to crank the engine for 3 min at 0 °C without using more than 25% of ampere-hour capacity; (d) a solid state battery charger of constant voltage that is two stage from trickle charge at standby to boost charge after use; and (e) the following regulation characteristics: (i) ± 1% output for ± 10% input variation; (ii) automatic boost for 6 h every 30 d; and (iii) equipped with a dc voltmeter, dc ammeter, battery charge meter, and on-off switch.

13.10.13.6 Generator control panel The generator control panel shall contain the following devices: (a) a three-position control switch (“Off-Auto-Manual”) for automatic starting units; (b) an air circuit breaker; (c) a voltmeter and ammeter; (d) a frequency meter; (e) an elapsed time meter; (f) an automatic voltage regulator and voltage adjustment rheostat; (g) alarm contacts for remote indication; (h) a device to automatically start the generator when the automatic transfer switch is in “Auto” mode; and (i) a battery charge meter.

13.10.14 Automatic electric power transfer Where two sources of electric power are available, power for continuous services such as lights and navigation signals may be transferred automatically from the normal feeder to the standby or emergency source on failure of the normal supply. On return of the normal power to at least 90% of rated voltage, the load may be retransferred after an adjustable time delay of not less than 5 min and after the bridge motion November 2006

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has ceased. If the emergency source fails, the retransfer shall be instantaneous on return of normal power. The automatic transfer switch shall be of the circuit breaker or contactor type, electrically operated and mechanically held, with a single solenoid or motor mechanism and separate arcing contacts. It shall be enclosed in a cabinet and a circuit diagram shall be provided on the inside of the door. It shall also comply with CSA C22.2 No. 178 and shall have a separate disconnect to de-energize the power source during maintenance. Where both power sources are external, with one designated “Normal” and the other “Standby”, an auxiliary switch shall be provided to permit using either as the preferred source. Where the standby source is an engine-generator set, the automatic transfer switch shall be equipped with a pilot contact for remote automatic starting of the engine 3 s after normal source failure or after a drop of any phase to 70% or less of the rated voltage. The normal load circuits shall remain connected during this 3 s delay. When the standby generator delivers not less than 90% rated voltage and frequency, the load shall be automatically transferred. On transfer to normal, the engine shall run for a minimum of 5 min to permit engine cool-down and then automatically shut down. A time delay shall be provided to ensure that the transfer switch remains in the neutral position when transferring between normal and emergency positions. The transfer switch shall have a test button so that normal source failure can be simulated.

13.10.15 Electrically operated motor brakes Motor brakes for the span-driving motors shall meet the requirements of Clause 13.8.7 and shall be fail-safe-type disc or shoe brakes. They shall be held in the set position by springs with such force as is needed to provide the required retarding torques. Disc hubs or brake wheels for the motor brakes shall be mounted on the motor pinion shaft or on a motor shaft extension. Brakes shall be designed for intermittent duty for the required retarding torques and shall be designed to release when the current is on and to apply automatically when the current is cut off. Brakes for the span operation shall have hydraulic, mechanical, or electrical interlocks to ensure that all of the brakes will not be applied at the same time. The brakes shall be equipped with a means for adjusting the torque and shall be set in the shop for the specified torque. Each brake shall have a nameplate that shall state the torque rating of the brake and the actual torque setting (where it differs from the torque rating). Shoe brakes shall be designed in such a manner that it is possible to adjust the brakes or replace the shoe linings without changing the torque settings. All dc brakes shall be released by thruster units or shunt coil solenoids. Shunt coils shall have discharge resistors or surge suppressors so that opening the shunt coil circuit does not cause high transient voltage. All ac brakes shall be released by thruster units or, if specified by the Engineer, motor operators. Thruster motors exposed to the atmosphere shall be totally enclosed, non-ventilated, and have weatherproof insulation for the motor and conduit box. For shoe brakes the releasing mechanism shall be capable of exerting a force of at least 130% of the force actually required to release the brake when set at the specified torque and minimum expected ambient temperature. Brakes for other motors shall be solenoid-released shoe brakes or dry-type disc brakes and shall have an intermittent rating not less than the full-load torque of the motors. Brakes shall be of a construction that ensures uniform wear and shall have independent provisions for adjusting lining wear, equalizing clearance between friction surfaces, and adjusting the retarding torque. The brake linings shall not be affected by moisture. Solenoids, thruster units, and motor operators shall be moisture proof. Fittings shall be corrosion resistant. Thrusters for shoe brakes shall be provided with year-round oil. Shoe brakes shall have a hand-release lever permanently attached to the brake mechanism and arranged so that one worker can operate the releases easily and rapidly. Means shall be provided for latching the lever in the set and released positions. Disc brakes shall have provisions for hand release and be arranged so that one worker can operate them easily and rapidly and so that they can be latched in the released position.

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Where brakes are located outside the machinery house, they shall be of weatherproof construction or shall have a weatherproof housing. The housing shall be arranged to permit operation of the hand-release lever from outside the housing. Brakes installed on the moving span shall operate satisfactorily with the span in any position. Brakes shall have heating elements where needed to prevent the accumulation of moisture and frost. Brakes shall also provide for the addition of limit switches for control and lights to indicate the position of the brakes and their hand-release levers.

13.10.16 Electrically operated machinery brakes Motor brakes and machinery brakes for the span-operating machinery shall meet the requirements of Clauses 13.8.7.2 and 13.8.7.3, respectively.

13.10.17 Design of electrical parts Electrical parts for lift bridges, including wiring, switches, circuit breakers, controllers, and contactors, shall be designed for operation of the bridge using either normal or emergency power for the span loads specified in Clause 13.8 and for at least 30 min total continuous duration of the operating cycles with Clause 13.8.5.3 Case B loading. Electrical parts for bascule and swing bridges shall be similarly designed for bridge operation for the span loads specified in Clause 13.8 and for 30 min continuous operating cycles of Clause 13.8.5.3 Case B loading for bascule bridges and 30 min continuous operating cycles of Clause 13.8.5.2 Case A loading for swing bridges. The temperature rise of electrical parts under such operation shall not exceed that for which the part is normally rated in accordance with Clauses 13.10.3 and 13.10.39 and any other applicable clauses.

13.10.18 Electrical control 13.10.18.1 General Electrical control shall be classified as manual, semi-automatic, or automatic sequence control. Separate controllers shall be provided for the span-driving, bridge lock, wedge, and gate motors. For control of motors in parallel, the switches shall be interconnected so that all switches will be operated simultaneously by one handle. The controllers shall be arranged in such a manner that the operation of one motor can be cut out without affecting the operation of any other motor. When there are two main dc motors powering one output, the control shall be series, parallel, or series-parallel, as required, unless the current is furnished by a storage battery, in which case the control shall be of the series-parallel type. For parallel operation for ac, and for constant potential parallel or series-parallel operation for ac, there shall be mechanically interlocked reversing contactors and separate resistors for each motor. When two motors are connected to one hoisting machine, accelerating contactors shall be common to both motors, unless otherwise specified by the Engineer. For three-phase ac, each phase shall have its own resistors, so designed to give balanced current in all three phases. Some of the acceleration contactors shall be controlled by acceleration relays to ensure that the torques specified in Clause 13.10.7 are not exceeded. When common accelerating contactors are not used, the accelerating contactors shall be electrically or mechanically connected or designed in such a manner that the corresponding circuits in each motor control will be made simultaneously and, in the event of one motor being cut out, the control for the motor in service will operate satisfactorily. Controls for span-driving motors shall provide multi-speed (stepped) or variable-speed (stepless) control. Multi-speed controls shall be of the full-voltage magnetic, reduced voltage, wound rotor master switch (drum controller), or wound rotor face plate controller type. Variable-speed controls shall be of the following types: (a) solid state, of the four-quadrant type (for dc motors); (b) solid state variable-voltage silicon controlled rectifier (SCR) (for ac and dc motors); or (c) variable frequency (for ac motors). Motor controllers shall be constructed, selected, and installed in accordance with applicable CSA and NEMA requirements.

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Controls shall be arranged in such a manner that all motor brakes shall be held released when power is applied to the span-driving motors.

13.10.18.2 Manual sequence control For non-emergency manual sequence control, it shall be possible for the operator to initiate each interlocked function in sequence by push button, selector switch, and/or master switch control. Note: The steps in such a sequence may include (a) actuate traffic signals; (b) actuate approach gates; (c) actuate exit gates; (d) actuate barriers or retarders; (e) pull span locks; (f) release brakes; (g) open span by manually accelerating and decelerating span-driving motors; and (h) set brakes.

For emergency control, actions by the operator can include operation of bypass switches, selection of the emergency mode of span operation, and skew correction. When two motor brakes are used on a hoisting machine, a point of control for each motor brake shall be provided for each direction of travel so that the motor brakes can be applied separately. For tower-drive vertical lift bridges, two points of motor brake control for each direction of travel shall be provided when two motor brakes are used for the hoisting machine in each tower. Electrically operated machinery brakes may be controlled through contacts on the master switch or by a separate switch. If the machinery brakes are controlled by the master switch, the contacts shall be arranged in such a manner that all machinery brakes will be held released when power is applied to the span-driving motors, except when the seating switch described in this Clause is used. The sequence of the master switch contacts shall be arranged in such a manner that the machinery brakes can be applied by the operator whenever the span is coasting. One point of machinery brake control shall be provided for each direction of travel for all machinery brakes on a hoisting machine. If the machinery brakes are controlled by a separate switch, they shall normally be set and arranged in such a manner that they will be released by the operator before the bridge is put in motion. They shall be held in release during the entire operation unless the operator desires to use them while the bridge is coasting or there arises an emergency requiring brake power exceeding that offered by the motor brakes, at which time they shall be capable of being applied instantly by the operator. The machinery brakes shall be designed in such a manner that they will not be injured if left in release indefinitely. When specified by the Engineer, brakes shall have at least three steps of retarding torque to permit partial application of the brakes. The machinery brake circuits shall be independent of the general interlocking system and there may be an electrically operated interlocking device that will prevent the use of the span-driving motor and the machinery brakes against each other except by use of the seating switch described in this Clause. A seating switch for applying the machinery brakes with power still on the motors shall be provided to enable the span to be drawn tightly to its seat and held in that position. The seating switch shall be convenient to the operator and shall be hand or foot operated. For tower-drive vertical lift bridges, one point of control for each direction of travel shall be provided for all machinery brakes. All brakes shall be applied automatically if the span attains a predetermined skew. Motors for bridge locks, wedges, and other devices associated with the movement of the span shall be controlled through magnetic contactors energized by control switches or push buttons independent of the span-driving motor controls.

13.10.18.3 Semi-automatic sequence control Procedures for semi-automatic sequence control shall be the same as those for manual sequence control, except that the span-driving motors shall be automatically accelerated and decelerated by the single operation of a push-button or selector switch.

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13.10.18.4 Automatic sequence control For non-emergency automatic sequence control, it shall be possible for the operator to initiate each interlocked function in sequence by one movement of a push button or selector switch. Note: The steps in such a sequence may include (a) actuate traffic signals; (b) actuate approach gates; (c) actuate exit gates; (d) actuate barriers or retarders; (e) pull span locks; (f) release brakes; (g) open span by manually accelerating and decelerating span-driving motors; and (h) set brakes.

For emergency control, actions by the operator can include operation of bypass switches, selection of the emergency mode of span operation, and skew correction. Span motor controls shall include all components needed to provide motor protection against abnormal conditions, automatic controlled acceleration and deceleration, modulated speed control (where applicable) (e.g., tower drives without power-synchronizing motors) and four-quadrant control to accommodate overhauling loads involving negative torque or regenerative braking loads, and any other feature needed to ensure satisfactory performance following a single movement of the initiating control switch. Motor and machinery brake types, and control arrangements, shall be selected so as to ensure time-sequenced brake application under all conditions. Two modes of stopping span movement shall be provided for variable-speed motor controls, as follows: (a) normal stop, with controlled electrical deceleration followed by brake application; and (b) immediate power cut-off and application of brakes initiated by an emergency stop button. Limit switch, resolver, or encoder actions shall initiate deceleration before the nearly open and nearly closed span positions are reached and the control system shall be designed to accomplish a reduction to slow speed when those positions are passed. Speed limit switches or some other means shall be provided to detect span speed at the nearly open and nearly closed positions. If the span speed is within the normal limit of the span, movement shall continue to completion; if not, power shall be cut off, brakes shall be applied, and a reset operation of the overspeed circuit shall be required before span movement can be resumed. During final seating, the motor torque shall be reduced and the brakes shall remain in released position until the span is tightly seated, after which the brakes shall set and the motors shall be disconnected. Tower-drive lift bridges arranged for automatic sequence control shall have two independent skew limit switches, resolvers, or encoders connected in series for each span mode of operation.

13.10.19 Speed control for span-driving motors Multi-speed (stepped) motor controls shall provide at least six steps of acceleration. These steps shall be such that (a) the motor torque will differ as little as practicable from the average torque required for uniform acceleration from zero speed to full speed; and (b) the bridge shall accelerate and decelerate smoothly (i) under the lowest friction conditions in the absence of wind or other extraneous unbalanced loads; and (ii) when the motors are carrying their maximum loads. Separate resistors shall be provided for each motor. Variable-speed (stepless) drives shall provide smooth variable-speed control with a minimum speed range of 10 to 1, independent acceleration and deceleration ramps field adjustable from 2 to 20 s minimum, speed regulation of ± 1.5% (or better), and motor slip. Variable-speed motor controls shall also provide four-quadrant control to accommodate overhauling loads, provide dynamic braking, and enable compatibility with programmable controllers.

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13.10.20 Master switches and relays for span-driving motors Master switches for the span-driving motors shall be cam-operated reversing switches with a single handle and shall have the necessary contacts and contact fingers for operating the magnetic contactors. The contacts and wearing parts shall provide for speed control of the motors. Adjusting plugs, screws, and nuts, including time-limit adjustments, shall be easily accessible so that acceleration relays can be adjusted for the proper timing intervals between acceleration steps. The contacts shall be removable without disturbing the setting of the relays.

13.10.21 Programmable logic controllers Programmable logic controllers (PLCs) shall be manufactured and tested to meet the requirements of the applicable CSA, IEEE, and NEMA Standards and shall be installed and grounded in accordance with the Canadian Electrical Code, Part I. The PLC system power supply and the input-output (I/O) system shall use a common ac source in order to minimize line interference and reduce the possibility of the PLC receiving faulty input signals. Unless otherwise specified by the Engineer, the ac source shall feed an uninterruptible power supply (UPS) inverter, complete with batteries and battery charger, that provides power to the PLC and I/O systems. The UPS shall be able to provide power for least 1 h. One or more regulation/isolation transformers shall be placed on the incoming ac power line to the PLC to stabilize the voltage to the PLC power supply and reduce the possibility of noise and interference. A properly rated power disconnect switch shall be placed in the power circuits feeding the PLC power supply and in the I/O system to remove power from the PLC system during an emergency. Master control relay (MCR) circuits shall be provided as a safe and convenient means for removing power from the I/O system during periods when PLC operation is intentionally halted, when PLC operation is unintentionally halted because of power loss or fault, or when there is an emergency stop condition. Grounding connections to the grounding electrodes and structural steel shall be provided using the exothermic method or brazing. Shielded cable shall be used to protect low-level signals from interference and the shields shall be continuous and connected to ground at one point only. The degree and type of shielding, the shield ground location, and the I/O surge protection shall be as recommended by the PLC manufacturer. A computer and appropriate software shall be provided for use as a diagnostic tool. The PLC may have a communication card installed to allow remote communication if required by the Owner.

13.10.22 Resistances and reactors Resistors for motor control shall, unless otherwise specified by the Engineer, be non-breakable, corrosion-resistant, and edgewise-wound or punched-grid resistor units. Resistors for the span-operating motors shall, unless otherwise specified by the Engineer, be of a capacity equal to a NEMA ICS 9 intermittent cycle rating providing for 15 s on out of every 30 s. The resistors shall be mounted on a steel frame or protected in another appropriate manner to ensure that they are free from injurious vibration, mounted in such a manner that free circulation of cooling air is permitted, and furnished in such a manner that any unit or part of a unit can be removed and replaced without disturbing the others. The units shall be insulated from their supports. For wound rotor motors with secondary resistance control, the controller shall be arranged in such a manner that a small amount of resistance shall always be left in the rotor circuits of each motor. This permanent resistance section shall be adjustable after installation and shall be proportioned for continuous duty. Reactors for secondary control of wound rotor motors shall be arranged to present the same reactance to each motor phase, mounted on a steel frame or protected in another appropriate manner to ensure that they are free from injurious vibration, and mounted in such a manner that free circulation of cooling air is permitted and they are protected from dripping liquids.

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13.10.23 Limit switches Limit switches shall be provided for the bridge locks, end and centre lifting devices, and gate motors and shall stop the motors and set the brakes automatically at each end of travel. Limit switches for the movable span shall have a master switch control that will cut off the current from the span-driving motors and set the brakes to stop the span in the nearly closed and nearly open positions. To fully close or fully open the bridge, it shall then be necessary to return the controller handle to the off position in order to bypass the limit switch contacts and regain control of the span. Where specified by the Engineer, relays that will prevent the bypass from functioning until a predetermined time after the brakes have set shall be provided. Additional limit switch contacts shall be provided to stop the span in the fully open position, and for swing bridges, where specified by the Engineer, in the fully closed position. Unless otherwise specified by the Engineer, the nearly closed and nearly open positions shall be taken to be 2 m from the fully closed and fully open positions, respectively. Fully seated switches that indicate to the operator when the bridge is fully closed shall be provided for vertical lift and bascule bridges. Tower-drive vertical lift bridges shall have skew limit switches mechanically connected to the machinery on the two towers, or equally effective switches of other types, that will cut off the current from the main motors and set the brakes to stop the span whenever it is more than a prescribed amount out of level. An ultimate skew limit switch, or a grouping of switches providing this function, shall also be provided to serve as a backup for the skew limit switch and stop the span at a larger amount out of level. Limit switches, resolvers, and encoders exposed to the weather shall be watertight and all exposed parts shall be corrosion resistant. Where plunger-type limit switches are used for fully seated switches, they shall be weatherproof and shall be provided with cast or malleable iron enclosures and stainless steel operating rods. Where specified by the Engineer, each fully seated limit switch shall be provided with a ball plunger to minimize bending stresses on the plunger rod. Electrically operated swing and bascule bridges shall include an overspeed limit switch to stop the span whenever normal span speed is exceeded. Lift bridges should also include such a switch. Movable spans shall have an overtravel switch that will prevent excessive travel beyond the fully open position.

13.10.24 Interlocking The operating mechanisms of all movable bridges shall be interlocked in such a manner that all devices can be operated only in the prescribed sequence. Emergency bypass switches that will free the motors from the prescribed interlocking in case of emergency shall be provided. These switches shall be conveniently mounted on the control desk or main switchboard. Each such emergency switch shall be sealed in the off position. Auxiliary and main power units shall be interlocked in such a manner that one is inoperative while the other is in service. Motor and machinery brakes shall have limit switches arranged in such a manner that the bridge shall be inoperable whenever any brake or combination of brakes is released by hand and the available braking torque left in service is insufficient to meet the requirements of Clause 13.8.7.

13.10.25 Switches An enclosed service-rated fused switch or circuit breaker with a pole for each ungrounded conductor shall be provided as a disconnect for the power system supply feeder. A similar switch, or a circuit breaker without the service rating to make it capable of being operated as a switch, shall be provided as a disconnect for each motor, light, signal, or other circuit. Main disconnect switches shall be of not less than 60 A capacity and shall have their enclosure doors interlocked with the switch mechanism. Toggle and tumbler switches shall be of corrosion-resistant construction and shall be of not less than 20 A capacity.

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13.10.26 Circuit breakers and fuses An automatic circuit breaker shall be placed in the supply line and have undervoltage release or trip coils to permit provision of undervoltage, phase reversal, and loss of phase protection. Where the supply has very large short-circuit capability, suitably rated current-limiting fuses may be provided in a disconnect switch ahead of the automatic circuit breaker, or otherwise incorporated into its design to accomplish alternative suitability. Where practicable, circuit breakers shall be used to provide short-circuit protection for all wiring circuits. The moulded-case circuit breaker selection process shall include a comparison of the short-circuit-interrupting ability of the I 2t rating (the integral of the square of the short circuit current, I, with respect to time, t, for the period of interruption) with the corresponding short-circuit capacity of the I 2t rating of the supply source connection. Moulded-case circuit breakers shall not be applied to circuits with possible short-circuit duty exceeding 60% of their rated interrupting ability or, if preceded by current-limiting fuses, their permissible I 2t source rating shall be at least 125% of the rated I 2t let-through of the preceding fuses for the particular application. A moulded-case circuit breaker or fuse shall be provided in each motor, brake, light, signal, indicator, or other circuit. For circuits above 600 V, air-break, vacuum-break, or oil-immersed circuit breakers shall be used (as service conditions dictate). Breakers shall have a pole for each phase wire feeding through the breaker, an overload device consisting of a thermal or magnetic element for each pole, and a common trip. Circuit breakers shall not be used for motor overload protection or for limiting the travel of any mechanism.

13.10.27 Contact areas For custom-designed electrical equipment such as slip rings for swing bridges, line contacts shall be avoided where practicable. The current per square inch (645 mm2) of contact area shall not exceed 50 A for spring-held contact or 100 A for bolted or clamped contact.

13.10.28 Magnetic contactors Magnetic contactors shall have an 8 h current rating not less than the current through the contactor when the connected apparatus is operating at rated load. Magnetic contactors shall be of the shunt type and shall be quick acting. Contacts shall be well shielded to prevent arcing between them and other metal parts nearby and shall be designed to be readily accessible for inspection and repair. Copper contacts shall have a wiping action. Contactors shall have double-break features or magnetic blowouts or an equivalent means for rapidly quenching the arc and shall have a minimum number of parts. All steel parts shall be corrosion resistant. Magnetic motor starters shall have not less than a 25 A rating unless otherwise specified by the Engineer.

13.10.29 Overload relays Overload relays (automatic or hand reset, as specified by the Engineer) shall be used in each phase or dc circuit for overload protection of all motors. Instantaneous magnetic overcurrent relays shall also be provided in motor circuits to de-energize all motors when the safe torque is exceeded, unless other means are provided for limiting the maximum torque.

13.10.30 Shunt coils Where shunt coils are used, the insulation shall be capable of withstanding the induced voltage caused by cutting off the current.

13.10.31 Instruments A line voltmeter, ammeters for span-driving motors, and a power bus wattmeter shall be provided and mounted on the control console. A voltmeter switch shall be provided for measuring the voltage between any two phases and between any phase and ground. Instruments shall be of the rectangular illuminated type, flush mounted, and back connected. Where specified by the Engineer, each hoisting machine at a tower-drive lift span shall have a wattmeter to determine the power required to operate each end of the span. All instruments mounted on the control console shall have a terminal voltage not greater than 120 V.

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13.10.32 Protection of electrical equipment Electrical equipment shall be protected from the weather and accumulation of debris.

13.10.33 Cast iron in electrical parts Where cast iron is used in switches and small electrical parts, it shall be of the malleable type.

13.10.34 Position indicators and meters Synchronous moving-span position indicators, skew indicators for tower-drive lift bridges, or electrical digital meters of the high-accuracy type guaranteed within ± 1° for angular measurements and ± 50 mm for linear measurements shall be provided. Transmitters, resolvers, or encoders shall be geared to trunnion shafts, counterweight sheave shafts, or machinery shafts, whichever are most suitable for the particular installation, and the receivers in the control console shall be geared to the indicators. Gearing shall be arranged so as to give the greatest practicable accuracy.

13.10.35 Indicating lights Indicating lights of suitable colours shall be installed on the control console to show span positions (at a minimum, the fully closed, fully open, nearly closed, and nearly open positions), and the positions of the traffic gates, bridge locks, and end lifting devices. Indicating lights shall also be provided to show the released position of each span brake, the overload or overheat tripping of span-drive motors, and the status of other functions. All indicating lights shall operate at not more than 120 V ac. Indicating lights shall be of the oil-tight push-to-test type. A testing capability for all indicating lights shall be provided by a spring-return selector switch or a single momentary contact push button.

13.10.36 Control console 13.10.36.1 General The span-control console shall contain switches for the span-operating motors and for the lock, end lift, and wedge motors; seating switches; bypass switches; switches for traffic gates and traffic signals; position indicators; indicating lights; and all other control devices and apparatus necessary for or pertinent to the proper operation and control of the span and its auxiliaries by the operator. The control console shall be located in a manner that affords the operator a clear view in all directions. The console shall be of cabinet-type construction, with a horizontal front section about 0.9 m above the floor and an inclined rear instrument panel set at such a slope that the meters can be read from average eye level without parallax and without reflection from the glass instrument cover. The console plan dimensions and the arrangement of equipment shall be such that all control devices are within easy reach. Edges shall be bevelled and neatly finished. Unless otherwise specified by the Engineer, the top of the console shall be stainless steel that is at least 3 mm thick and has a non-reflecting finish.

13.10.36.2 Construction The console frame shall be constructed of sheet steel at least 3 mm thick. All corners and edges of the console shall be rounded and the sheet steel shall be reinforced by flanging the metal into angle and channel sections. Connecting sections shall be properly joined by continuous seam welding or spot welding to provide a rigid free-standing structure. Outside surfaces shall be smooth and without visible joints, seams, or laps. The bottom of the console shall be left open. The supporting flange on the inside of the console frame at the bottom shall have suitable holes for bolting the console to the floor. Suitable brackets and angles shall be provided on the inside of the console in order to support the top and the equipment mounted thereon. The control console shall have hinged doors on the front and, in accordance with the requirements of the installation, doors, removable panels, or fixed panels on the back and sides. Doors shall be fitted with sturdy three-point latches operated by flush-type, chromium-plated handles, shall be assembled accurately, and shall have a clearance not exceeding 3 mm at any point. A toe space shall be provided on the front of the console at the bottom.

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The console, when finished, shall be given one coat of moisture-resisting primer and one coat of filler on all surfaces. The outside surfaces shall be given a non-reflecting finished coat of a colour as specified by the Engineer. The stainless steel console top shall be left unpainted. The console interior shall be equipped with suitable lights controlled from a switch on the console. Each piece of equipment and each indicating light on the control console shall have a properly engraved metal or lamicoid nameplate with black characters on a white background. The designations on the nameplates shall correspond with those shown on the wiring diagrams and in the operating instructions.

13.10.36.3 Controls The off position of master switch handles shall be located toward the front of the console. For bascule and swing bridges, the direction of rotation of each master switch shall be such that when it is moved from the off position, the span, as seen by the operator, will move in the same direction as the master switch handle. For double-leaf bascule bridges, the switches shall rotate in opposite directions. For vertical lift bridges, clockwise rotation shall raise the bridge. For bridges that have automatic controls, push buttons, industrial-type touch screens, or menu-driven graphical interfaces may be provided. Bridges that have automatic controls shall also be provided with controls for manual operation, which may be of the push button type. Foot-operated seating switches may be supported by the outside of the console or set in a suitable recess at the bottom of the console. This foot recess shall be rounded at the top to a 30 mm radius. Outgoing control connections from the console shall be brought to suitably marked barrier-type terminal boards supported on straps securely attached to the console frame. Terminal boards shall be located in such a manner that they do not interfere with door access to the inside of the console. Wires shall be brought from the terminal boards to their respective terminals in an orderly arrangement, properly bunched and tied.

13.10.37 Control panels Control panels shall be of enclosed, dead front, free-standing construction, EEMAC Type 1 or better, and should be of standard industrial motor control centre-type construction. Motor control centres shall be constructed in accordance with the Canadian Electrical Code, Part I, applicable NEMA and EEMAC Standards, and UL 845. All disconnect switches, circuit breakers, contactors, relays, rectifiers, instrument transformers, and other electrical equipment for the control of the span and its auxiliaries shall be mounted on or in the control panels. Equipment mounted at the bottom of the panel boards shall clear the floor by at least 150 mm. Open control panels shall not be used. Control panels shall be front wired. Interconnections shall be made by copper bus bars or insulated cables of equivalent current-carrying capacity. Board wiring shall terminate in terminal strips supported in a substantial manner and all conductors shall be copper. Each piece of equipment on the board shall have a properly engraved nameplate that meets the requirements of Clause 13.10.36.2.

13.10.38 Enclosures for panel boards Enclosures for panel boards shall, unless otherwise specified by the Engineer, be general-purpose enclosures that comply with Canadian Electrical Code, Part I, and EEMAC requirements for Type 1 general-purpose enclosures. They shall be provided with suitably arranged doors to give access to the front of the board, shall be made of sheet steel at least 3 mm thick (welded and flanged in a manner that will result in a rigid free-standing structure), and shall be finished in the manner specified in Clause 13.10.36.2. Note: The sheet steel composition and finishing requirements of this Clause include the doors and panels of enclosures.

13.10.39 Electrical wires and cables Electrical wires and cables (including their insulation and covering), shall be of a quality that satisfies applicable CSA, EEMAC, and Insulated Power Cable Engineers Association (IPCEA) Standards. Where these requirements do not apply, electrical wires and cables shall conform to ASTM requirements.

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Unless otherwise specified by the Engineer, wires external to the control console and control panels shall be protected by conduit or armour or be suitably jacketed. They shall be rubber-insulated, rubber-jacketed wires with an insulation of a quality at least equal to synthetic rubber moisture-resisting 60 °C or Type THWN or XHHW. Insulated wire for connections on the backs of control panels and in control consoles shall be thermoplastic insulated wire that complies with UL requirements for Type THWN wire, 600 V. Insulated wire for connections to motor resistance grids shall have insulation rated for 250 °C (Types TFE, TGGT, and TKGT meet this requirement). All wires shall be stranded copper. No wires smaller than No. 12 AWG shall be used, except that No. 14 AWG shall be permitted for connection to internal control components where the use of No. 12 AWG would be impracticable for control console, control panel, or interlocking device wiring. The ends of all wires that are No. 8 AWG or smaller shall have solderless high-compression indent-type terminals where they terminate at control panels, control consoles, terminal strips, lighting panels, junction boxes, and similar locations. The ends of larger wires shall be similar and shall terminate in pressure lugs or screw-type solderless connectors.

13.10.40 Tagging of wires To enable any wire to be traced from terminal to terminal, wires shall be numbered and the numbers permanently marked on durable fibre tags, on metal or plastic bands with protective heat-shrunk sleeving, or on such other material specified by the Engineer. The numbers shall correspond to those shown on the wiring diagrams.

13.10.41 Wire splices and connections Wire splices and connections shall be made only on terminals and within enclosures intended for the purpose. Wires shall be continuous from terminal to terminal.

13.10.42 Raceways, metal conduits, conduit fittings, and boxes 13.10.42.1 General Except as otherwise specified by the Engineer, conduits shall be hot-dip galvanized schedule 40 steel or alloy steel pipe, with a factory-fused and bonded polyvinylchloride plastisol coating and shall be not less than 3/4 NPS (National Pipe Size). All couplings, locknuts, and bushings shall be standard screw type; setscrew-type couplings, locknuts, and bushings shall not be used. Bushings shall be of the insulating type. Conduit entrances to sheet metal enclosures shall have sealing O-rings or liquid-tight hub fittings.

13.10.42.2 Conduit size The conduit size shall be such that the total areas of the wires, including insulation, shall not exceed the percentage of the area of the conduit specified by the Canadian Electrical Code, Part I. Phase wires in ac motor circuits shall be placed close together in one conduit to lessen the inductive effects. The circuits for not more than three ac motors may be in one conduit.

13.10.42.3 Boxes and fittings Suitable conduit outlet boxes, junction and pull boxes, ells, and other fittings shall be used with conduits. Boxes, outlets, and other fittings shall be of cast iron or malleable iron of sufficient thickness to permit the conduit to be threaded into the fitting and shall be hot-dip galvanized. Boxes and other fittings shall be weatherproof throughout, free from rough edges and rough surfaces, and unless otherwise specified by the Engineer, of Canadian Electrical Code, Part I, and EEMAC Type 4 construction, unless housed in a room. Large boxes for which cast iron or malleable iron is not practicable may be built of steel plates and angles at least 4.7 mm thick, with all joints continuously welded, and shall be provided with drain holes.

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13.10.42.4 Bends Bends in conduits shall be used sparingly. The total angle of all bends in one conduit run should not exceed 180°. Where the conduit is bent, the radius of the bend to the centre of the conduit shall be at least eight times the inside diameter of the conduit (except for factory ells). Conduits shall have drain holes placed in tee-connections located at the low points. So far as possible, conduits shall be run in lines parallel and perpendicular to the principal lines of the house and structure. Embedded conduits shall be carefully rodded after placing with a device that will ensure that the whole interior surface of the conduit is free of obstructions. The conduit shall be temporarily protected by conduit closures or pipe caps until the wires are pulled and the conduit is permanently closed.

13.10.42.5 Conduit supports Conduits shall be placed so that dirt will not accumulate around them and shall be firmly clamped to the structure by supports on not more than 2 m centres to prevent rattling. There shall be at least 25 mm clearance between conduits and at least 100 mm clearance between conduits and the supporting structure. Adequate provision for conduit movement shall be made wherever conduits cross expansion joints in the supporting structure. Conduit runs between the bridge and solidly based structures, such as piers and operator’s houses, shall include at least 300 mm of liquid-tight flexible metal conduit at the interface with bonding jumpers.

13.10.42.6 Conduit connections Conduit connections to motors, generators, limit switches, brakes, and other devices specified by the Engineer shall include at least 500 mm of slack liquid-tight flexible metal conduit.

13.10.42.7 Wireways and cable trays Where bridges have a relatively large amount of equipment and an extensive control system, consideration shall be given to the use of wireways or continuous rigid cable supports instead of the exclusive use of conduits above the control panels and with control console connections. Where wireways are used, they shall be of the full-lay type with a cross-section of at least 200 x 200 mm (preferably 300 x 300 mm) to adequately accommodate the recommended bending radii of all cables. Where continuous rigid cable supports are used, all cables supported by such supports shall meet Canadian Electrical Code, Part I, requirements. Wireways and trays shall not be used outside the operator’s house except with armoured cables.

13.10.43 Electrical connections between fixed and moving parts 13.10.43.1 General Electrical connections for carrying current between fixed and moving parts shall be made using the flexible cables or collector rings described in Clauses 13.10.43.2 and 13.10.43.3 or another suitable method, as specified by the Engineer.

13.10.43.2 Flexible cables Conductors in flexible cables shall have extra-flexible stranding. The cables shall be connected to terminal strips in junction boxes at which the wiring in conduits terminates. Short cables with relatively small movement of the moving part with reference to the fixed part, e.g., cables extending from a fixed pier to a fender not rigidly attached to the pier, shall be extra-flexible round portable cable covered with a neoprene jacket or protected with corrosion-resistant metal armour. Long cables with relatively large movement of the moving part with reference to the fixed part, e.g., vertical cables hanging in a loop between the end of a vertical lift span and a tower, shall be rubber-insulated flexible cables covered with an internally reinforced neoprene jacket. Such cables shall be suspended from segmental supports arranged to prevent sharp bends in the cables as the span moves.

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13.10.43.3 Collector rings On swing bridges, the connection between the fixed part and the swing span may be made through shoes sliding on circular collector rings attached to the centre pivot. The collector rings shall be protected by a removable metal casing.

13.10.44 Electrical connections across the navigable channel Electrical connections for carrying current across the navigable channel shall be made as specified by the Engineer. They shall be made using submarine or overhead cables (submarine cables are preferred, but, particularly for vertical lift bridges, overhead cables can be a more suitable choice). The voltage, number of conductors in each cable, size and number of strands in each conductor, construction of the cable, and other such characteristics shall be as specified by the Engineer. Each cable shall provide a number of spare conductors. The following requirements shall also apply: (a) Submarine cables shall be armoured with spiral-wound galvanized steel wire armour and, if specified by the Engineer, covered with a neoprene jacket. Individual wires shall meet the requirements of Clause 13.10.39. Submarine cables shall be provided with conductor insulation suitable for submarine use. Unless otherwise specified by the Engineer, submarine cables shall be placed at least 1.5 m below the bed of the channel. Cables shall be long enough to provide ample slack. (b) Overhead cables shall be jacketed with neoprene or another superior jacketing compound resistant to weather and aging. Individual wires shall meet the requirements of Clause 13.10.39. Overhead cables shall be installed in accordance with CAN/CSA-C22.3 No. 1. Each cable shall be suspended from a messenger strand at intervals of at least 500 mm. Messenger strands shall be strung with a sag required to safely support the entire construction under the conditions of ice, wind, and temperature applicable to the location of the bridge, shall be of high-strength material, and shall be adequately anchored to steel framework at their ends. Messenger strands, cable hangers, and all accessories shall be protected against corrosion in a manner that ensures a service life not less than that of the overhead cable.

13.10.45 Service lights A complete electric lighting system shall be installed for the operator’s house, machinery house, stairways, vertical lift span tower tops, signals, machinery, and end lifting and locking apparatus and at all other points where periodic inspection or maintenance of equipment is required. Lighting systems shall be designed to produce at least the following intensities measured 1.0 m above floor level: (a) operator’s house: 300 lx; (b) machinery house: 200 lx; (c) unhoused machinery: 150 lx; and (d) walkways and stairways: 200 lx. Lighting may be fluorescent, incandescent, or mercury vapour, or any other suitable type. All fixtures fitted with incandescent lamps smaller than 100 W shall be equipped so that lamps up to 100 W can be used. Conductors shall be at least No. 12 AWG in size. The lights in the operator’s room should have dimming adjustment from the control console. In machinery houses, there shall be fixed pendants of suitable length, with enclosed fixtures or fire-enamelled steel dome reflectors. Vapour-tight fire-enamelled steel dome reflectors or enclosed fixtures shall be provided for exterior lighting. Lampholders shall have shock-absorbing porcelain sockets. Convenience outlets shall be provided in each room of the operator’s house, in machinery houses, at bridge lock and wedge machinery, at submarine cable terminal cabinets, and at all locations where occasional inspection or maintenance of equipment is required. They shall be of the twin-receptacle three-wire grounding type. Convenience outlets exposed to the weather shall be weatherproof and have a ground fault circuit interrupter installed.

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13.10.46 Navigation lights Navigation and other light fixtures on the movable span and on fenders shall be capable of withstanding shocks and rough treatment, completely weatherproof, and made of bronze or aluminum. Light fixtures shall have shock-absorbing porcelain sockets and lamps rated between 100 and 150 W. LED technology lighting may be considered if permitted by the authority having jurisdiction.

13.10.47 Aircraft warning lights Aircraft warning lights shall be provided when required by Transport Canada or other Regulatory Authority.

13.10.48 Circuits Circuits shall be classified as follows: (a) power circuits: (i) motors; and (ii) other; (b) control circuits: (i) span; (ii) bridge locks; (iii) wedges; (iv) gates; and (v) other; and (c) lighting circuits: (i) navigation and marking or warning lights; (ii) service lights; (iii) convenience outlets; and (iv) other. An independent circuit shall be provided for each motor, each control circuit, the navigation lights, each group of service lights, and each group of convenience outlets. Common neutral return wires shall not be used. Each circuit shall be protected and controlled by its own circuit breakers, fuses, and switches located on the panelboards or at an equally convenient point.

13.10.49 Grounding and lightning protection Movable bridges shall have grounding and lightning protection systems that meet or exceed the requirements of the Canadian Electrical Code, Part I, and the provincial or territorial lightning rods statute (or CAN/CSA-B72 if these is no provincial or territorial statute). The power supply shall be one of the following types (in order of preference): (a) solidly grounded (most preferred); (b) resistance grounded; or (c) ungrounded (least preferred). Ground-indicating lights shall be provided, except for solidly grounded systems. The metal portions of the bridge shall have grounding conductors connected to low-resistance grounding electrodes. An electrical system ground bus, and connections to all major electrical equipment (including each motor, each brake, the aircraft warning lights, and the land-based navigation lights) shall be provided.

13.10.50 Spare parts In the absence of Owner-specified requirements, the following list of spare parts may be included in the contract for supply by the contractor: (a) six fuses of each size and kind; (b) one complete set of stationary and moving contacts for each size of each device; (c) one indicating light unit, complete with lamp and fitted with a coloured cap, for each size, type, and colour used; (d) one spare circuit breaker for each size and kind used;

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(e) one control relay and two extra sets of contacts for each type; (f) one complete set of contacts and one operating coil for each size and type of magnetic contactor and motor starter; (g) one brake coil or thruster motor for each size of brake, or one complete brake; (h) one set of brushes and one set of motor bearings for each size of motor; and (i) spare parts for engines, engine-generator sets, skew and positioning indicating devices, electronic control components, tachometers, motor secondary impedance elements, and other parts.

13.11 Construction 13.11.1 Shop assemblies All shafts, gears, pinions, and other parts supported by common machinery frames or cases shall be assembled in the shop and tested by operation where possible in order to prove fits and clearances before shipping to the field ready to be set in place. Where practicable, machinery parts shall be assembled in the supporting structural members in the shop. They shall be aligned and fitted, and holes in the supports shall be drilled, with all components in their correct relative positions. The members shall be match-marked to the supports and to each other and erected in the field in the same relative positions. When this assembly method is not possible, the holes in the machinery parts shall be drilled in the shop and holes in the supports shall be left blank for drilling in field assembly after final alignment. If any undersize holes are shop drilled to aid field alignment of machinery, they shall be reamed to fit the permanent bolts after all other holes have been drilled and their bolts placed. The complete centre pivot arrangement of swing bridges, including rim girders, centre pivot, radial members, rack, track, and rollers, shall be shop assembled. All parts shall be aligned, fitted, and match-marked before disassembly. The tread and track components of rolling lift bridges shall be shop assembled to the segmental and track girders, respectively; aligned, fitted, and drilled; and the parts match-marked for field assembly. Built-up counterweight sheaves shall be assembled, welded, and stress-relieved before finish machining is performed. Where journal bearings are used, each trunnion shaft shall be shop assembled to its bearings and the linings shall be scraped to a true fit in the journals. Parts that are likely to be damaged by weather or handling shall be suitably crated or otherwise protected for shipment. The rubbing surfaces of trunnions, shafting, and machinery bearings shall be protected by suitable anti-rust compounds and lagged with wood.

13.11.2 Coating The surfaces of machinery parts, except rubbing surfaces, shall be cleaned and coated, in the shop and in the field, as specified by the Engineer. The colours shall be the Approved safety colours for machinery components. A minimum three-coat system shall be used.

13.11.3 Erection 13.11.3.1 Structural Erection shall be performed in accordance with Clause 10.24 and the applicable requirements of this Section. Movable spans may be erected in either the closed or the open position, depending on navigational requirements, the season of the year, and other site conditions indicated on the drawings.

13.11.3.2 Machinery The installation and adjustment of machinery shall be carried out by millwrights skilled in this type of work. Final alignment and adjustment of machinery parts whose relative position is affected by the deflection or movement of the supports under full dead load, or of the span under full dead load, shall not occur until such deflection or movement has taken place.

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Machinery parts previously aligned and assembled in the shop shall be erected according to the match-marks. Where final alignment and the drilling of holes in supporting members in the field is required, the machinery components shall be adjusted to the proper elevation and aligned through the use of shims. The holes in the supporting steel shall be drilled while the parts are assembled. Shims shall not be smaller than the bearing area shimmed. The trunnion bearings of bascule bridges and the counterweight sheave bearings of vertical lift bridges shall be aligned with special care and due allowance shall be made for the deflection of the bearing seats that can result from the working load on the bearings. Deflections of this nature shall have been previously calculated and the method to be used for securing proper alignment shall be shown on the contractor’s erection drawings. Before the ropes are placed over counterweight sheaves, the bearings shall be lubricated and each sheave shall be turned to prove that it runs freely in its bearings. The tension in counterweight ropes on each sheave shall be adjusted so that the maximum and minimum tension does not vary more than 5% from the average tension in all ropes on any one sheave. All open gearing shall be aligned so that backlash is within tolerance and at least the centre 50% of the face width of each pair of meshing teeth is in contact. The cross-mesh shall not exceed 0.25 mm per 150 mm (0.01 in per 6 in) of face width. All open gear measurements, including main pinion and racks, shall be submitted to the Engineer for review and approval. The measurements shall include backlash, cross-mesh alignment, tooth valley gap, and face contact. The type of bluing or lubricant used for face contact measurements shall be submitted to the Engineer for approval before any measurements. The measurements shall be performed at a minimum of eight equally spaced span positions ranging from fully open to fully closed.

13.11.3.3 Protection from damage Electrical components and other parts that are protected from the weather in the finished structure shall be protected in the field during erection by temporary housing or other suitable means. All machinery parts shall be carefully protected from damage during transit, unloading, and storing while awaiting erection. All finished surfaces that were shop coated with protective rust-inhibiting grease or another medium shall be cleaned of the protective coating(s) immediately before erection. Wire ropes shall be housed and stored at least 460 mm above the ground. The ropes shall be kept free of dirt, cinders, and sand. Wire ropes shall be carefully removed from reels or coils by revolving them and shall be erected in a manner that avoids sharp kinks or bends. They shall not be dragged across the ground. The stripe painted on each counterweight rope shall be straight after the rope is erected.

13.11.3.4 Items for initial operation The contractor shall furnish grease, oil, fuel, and any other item necessary for the preliminary operation of the movable bridge until it has been accepted by the Owner, except for electric power, which shall be supplied by the Owner. The supplied grease and oils shall be subject to the approval of the Engineer.

13.11.3.5 Treatment of ropes As soon as the movable span can be operated, the contractor shall thoroughly remove any foreign material from ropes and apply one coat of approved wire rope lubricant. The types of lubricant to be used on the operating and counterweight ropes and the method of application shall be specified by the Engineer. The application shall be made to the satisfaction of the Engineer.

13.11.3.6 Counterweights The contractor shall adjust the counterweight so that the moving span is balanced according to the drawings. Approval of any balance calculations, or of any materials or processes, shall not relieve the contractor from the entire responsibility for obtaining a satisfactory balance. For satisfactory balance, the movable span shall have a slight closing force present when it is seated and either a neutral or a very slight opening force present when it is fully open. Note: Balance can be checked in the field using the following procedures: (a) compare motor currents during opening and closing of the span; (b) compare power meter (kilowatt) readings during opening and closing of the span;

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(c) run a drift test from the mid-position of travel in both the opening and the closing direction. Compare the drift in each direction with power off and the brakes released; (d) measure the torque in the drive train during opening and closing of the bridge; (e) compare the grease patterns on the main pinion teeth; and (f) for vertical lift bridges, weigh the imbalance between the span and the counterweights.

13.11.3.7 Testing Before the main operating machinery is connected for transmitting power, it shall be given an idle run for at least 4 h to the satisfaction of the Engineer. When the entire installation has been completed, the movable span, including all accessories, shall be operated through not fewer than three complete cycles using normal power, prime movers, and controls, and through at least two complete cycles using emergency power, emergency prime movers, and controls. If inspection during and after these tests shows that any components are defective, inadequate, or functioning improperly, the contractor shall make the necessary corrections, adjustments, or replacements.

13.12 Training and start-up assistance For power-operated bridges, the contractor shall provide specialist personnel for 30 d after acceptance, on the basis of one 8 h shift per day, plus emergency service if required. These personnel shall supervise the operation of the bridge and instruct the operator in its proper operation and maintenance.

13.13 Operating and maintenance manual Every movable bridge shall have an operating and maintenance manual. The bridge contractor shall supply the number of copies of the manual specified by the Owner. The manual shall include a schedule of normal and emergency testing of bridge operations and a step-by-step explanation describing the sequence and interlocks of each operation. It shall also state the maximum operating wind speed. It shall include instructions for the maintenance, lubrication, and adjustment of mechanical and electrical parts and copies of all instruction manuals, bulletins, etc. relating to any commercial devices that form part of the mechanical and electrical systems that operate the bridge. It shall be revised as needed to include updated information if changes are made to mechanical and electrical systems. The manual shall also include the following: (a) a schematic wiring diagram; (b) “as fitted” wiring diagrams; (c) “as fitted” conduit and wire layouts; (d) “as built” machinery erection drawings; (e) machinery shop drawings; (f) a machinery lubrication checklist and drawings; (g) a list of the names and addresses of local distributors of all standard components; (h) where PLC controls are used, a hard copy and soft copy of the software program; (i) a detailed listing of all of the interlocks employed in the electrical controls of the movable bridge; (j) where control devices are employed in the control of the movable bridge and require calibration and setting of set points, a listing of such devices, along with their set points; (k) a copy of the testing and commissioning records; and (l) hydraulic schematic diagrams.

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13.14 Inspection The Engineer shall specify the frequency and types of inspections recommended for long-term durability and trouble-free operation of the movable bridge. The frequency and types of inspections shall be consistent with the use of the facility, i.e., seasonal or year-round operation. Scheduled inspections shall include the following at a minimum: (a) An annual visual and aural inspection. In the case of seasonal use, this should be at the start of the season. This inspection shall take into consideration the adequacy of the maintenance of the bridge. (b) A comprehensive inspection at not more than two-year intervals. This inspection shall include structural safety, wear and alignment of mechanical components, and any breaks, defects, or hot spots in the electrical system. All inspections shall be followed by a written report. The design shall incorporate the necessary means to facilitate inspection of all components requiring inspection.

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Section 14 — Evaluation 14.1 14.2 14.3 14.4 14.4.1 14.4.2 14.4.3 14.4.4 14.5 14.5.1 14.5.2 14.5.3 14.5.4 14.5.5 14.6 14.6.1 14.6.2 14.6.3 14.6.4 14.7 14.7.1 14.7.2 14.7.3 14.7.4 14.7.5 14.8 14.8.1 14.8.2 14.8.3 14.8.4 14.8.5 14.9 14.9.1 14.9.2 14.9.3 14.9.4 14.9.5 14.10 14.11 14.11.1 14.11.2 14.11.3 14.11.4 14.12 14.12.1 14.12.2 14.12.3 14.12.4 14.12.5 14.13 14.13.1

Scope 643 Definitions 643 Symbols 643 General requirements 646 Exclusions 646 Expertise 646 Future growth of traffic or future deterioration 647 Scope of evaluation 647 Evaluation procedures 647 General 647 Limit states 647 Deleted Evaluation methodology 648 Bridge posting 648 Condition inspection 648 General 648 Plans 649 Physical features 649 Deterioration 649 Material strengths 649 General 649 Review of original construction documents 649 Analysis of tests of samples 649 Strengths based on date of construction 650 Deteriorated material 651 Permanent loads 651 General 651 Dead load 651 Earth pressure and hydrostatic pressure 652 Shrinkage, creep, differential settlement, and bearing friction 652 Secondary effects from prestressing 652 Transitory loads 652 Normal traffic 652 Permit — Vehicle loads 656 Dynamic load allowance for permit vehicle loads and alternative loading 657 Multiple-lane loading 657 Loads other than traffic 658 Exceptional loads 659 Lateral distribution categories for live load 659 General 659 Statically determinate method 659 Sophisticated method 659 Simplified method 659 Target reliability index 659 General 659 System behaviour 660 Element behaviour 660 Inspection level 660 Important structures 660 Load factors 661 General 661

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14.13.2 14.13.3 14.14 14.14.1 14.14.2 14.14.3 14.15 14.15.1 14.15.2 14.15.3 14.15.4 14.16 14.16.1 14.16.2 14.16.3 14.16.4 14.17 14.17.1 14.17.2 14.17.3 14.18

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Permanent loads 662 Transitory loads 662 Resistance 665 General 665 Resistance adjustment factor 672 Effects of defects and deterioration 673 Live load capacity factor 674 General 674 Ultimate limit states 674 Serviceability limit states 675 Combined load effects 675 Load testing 675 General 675 Instrumentation 676 Test load 676 Application of load test results 676 Bridge posting 677 General 677 Calculation of posting loads 677 Posting signs 678 Fatigue 679

Annexes A14.1 (normative) — Equivalent material strengths from tests of samples 680 A14.2 (normative) — Evaluation Level 1 (vehicle trains) in Ontario 682 A14.3 (normative) — Evaluation Level 2 (two-unit vehicles) in Ontario 683 A14.4 (normative) — Evaluation Level 3 (single-unit vehicles) in Ontario 684

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Section 14 Evaluation 14.1 Scope This Section specifies methods of evaluating an existing bridge to determine whether it will carry a particular load or set of loads.

14.2 Definitions The following definitions apply in this Section: Capacity — the unfactored nominal resistance of an element or joint. Evaluation — determination of a bridge’s capacity to carry traffic loads. Evaluation Level 1 — evaluation of a bridge to determine its load-carrying capacity for vehicle trains (in normal traffic). Evaluation Level 2 — evaluation of a bridge to determine its load-carrying capacity for two-unit vehicles (in normal traffic). Evaluation Level 3 — evaluation of a bridge to determine its load-carrying capacity for single-unit vehicles (in normal traffic). Evaluator — a qualified Engineer responsible for evaluating a bridge. Normal traffic — vehicular traffic that does not include any vehicle operating under a permit for weights, dimensions, or both that do not meet regulatory limits. Posting — signing of a bridge for load restrictions in accordance with regulations. Single-unit vehicles — trucks, buses, cars, and other vehicles consisting of a single unit. Two-unit vehicles — tractor–semi-trailers, car-trailers, truck-trailers, and other vehicles consisting of two units. Vehicle trains — tractor-trailer-trailers, tractor–semi-trailer–trailers, tractor–semi-trailer–semi-trailers, and other vehicles consisting of three units.

14.3 Symbols The following symbols apply in this Section: A

= force effects due to additional loads (including wind, creep, shrinkage, temperature, and differential settlement) that may be considered in the evaluation

Asl

= area of longitudinal tensile reinforcing steel in the bottom of concrete deck slabs, mm2

Ast

= area of transverse tensile reinforcing steel in the bottom of concrete deck slabs, mm2

Ar

= nominal area of a rivet, mm2

Av

= area of transverse shear reinforcement perpendicular to the axis of a member within a distance s, mm2

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a

= length of end split, crack, or check measured into the span from the centreline of the support to the tip of the split, mm

Br

= factored bearing resistance of a riveted connection, N

b

= width of a component, mm

bv

= effective web width within depth dv , mm (see Clause 8.9.1.6)

CR

= loss of prestress due to creep of concrete, MPa

D

= nominal (unfactored) dead load effect

D

= mean dead load effect

d

= diameter of a rivet, mm; depth of a wood member, mm

dl

= depth from the top of a slab to the centroid of bottom longitudinal tensile reinforcing steel, mm

dt

= depth from the top of a slab to the centroid of bottom transverse tensile reinforcing steel, mm

dv

= effective shear depth, mm

e

= edge distance, mm

F

= live load capacity factor

Fc

= correction factor for concrete deck punching shear capacity as a function of fc’

Fq

= correction factor for concrete deck punching shear capacity as a function of q

Fu

= specified tensile strength of structural or rivet steel, MPa

Fy

= nominal value of yield strength of steel, MPa

fc

= average of measured strengths of 100 mm diameter concrete cores after modification in accordance with Clause A14.1.2, MPa

fc’

= specified compressive strength of concrete, MPa

fcr

= cracking strength of concrete, MPa

fps

= calculated stress in prestressing steel at ultimate limit state, MPa

fpu

= specified tensile strength of prestressing steel, MPa

fpy

= specified yield strength of prestressing steel, MPa

fse

= effective stress in prestressing steel after losses, MPa

fsj

= stress in prestressing steel at jacking, MPa

fst

= stress in prestressing steel at transfer, MPa

fy

= specified yield strength of reinforcing bars, MPa

fy h I

= average of measured values of yield strength of reinforcing steel or structural steel, MPa

kc

= factor to modify coefficient of variation of concrete core strengths (Table A14.1.2)

ks

= factor to modify coefficient of variation of steel coupon strengths (Table A14.1.1)

ksv

= size effect factor for shear of wood members (see Clause 14.14.1.7.2)

L

= nominal (unfactored) static live (traffic) load effect

L

= mean static and dynamic live (traffic) load effect

La

= factored total load effect in masonry arches

Lt

= unfactored load effect from test loading

Lwf

= factored wheel load (including dynamic load allowance), kN

m

= number of shear planes in a riveted joint (equal to one for rivets in single shear and two for rivets in double shear)

n

= number of rivets; number of strength tests

644

= overall thickness or depth of a component, mm = nominal (unfactored) dynamic component of the live load, expressed as a fraction of the nominal static live load effect (dynamic load allowance)

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P

= posting factor

Pn

= unfactored resistance of a masonry arch, kN

Pr

= factored resistance of a masonry arch, kN

q

= average percentage of tensile reinforcement in the two directions in which steel is placed at the midspan of a slab panel (see Clause 14.14.1.3.3); uniformly distributed portion of lane load, kN/m

R

= nominal unfactored resistance, kN, calculated using the material strengths as specified in Clause 14.7.1 and in accordance with the requirements of Sections 6 to 12 and Clause 14.14

R

= mean resistance, kN

REL1

= loss of prestress due to relaxation of prestressing steel prior to transfer, MPa

REL2

= loss of prestress due to relaxation of prestressing steel after transfer, MPa

Rd

= nominal resistance of a concrete deck slab, kN

Rn

= unfactored (nominal) resistance of a concrete deck slab, kN

Rr

= factored resistance of structural component, kN

SD

= standard deviation of dead load force effects

SL

= standard deviation of live load force effects

SH

= loss of prestress due to shrinkage of concrete, MPa

s

= spacing of stirrups measured parallel to the longitudinal axis of a component, mm

sm1

= maximum allowable spacing below which a section is considered to have full transverse reinforcement, mm

sm2

= maximum allowable spacing above which a section is considered not to have transverse reinforcement, mm

sr1

= maximum allowable spacing, as a fraction of shear depth, below which the section is considered to have transverse reinforcement

sr2

= maximum allowable spacing, as a fraction of shear depth, above which the section is considered not to have transverse reinforcement

Tf

= tensile force in a member or component at the ultimate limit state, N

Tr

= factored tensile resistance of a riveted joint, N

t

= thickness of a steel component, mm; thickness of a concrete deck slab, mm; time, d

U

= resistance adjustment factor

V

= coefficient of variation

VAD

= coefficient of variation for dead load analysis method

VAL

= coefficient of variation for live load analysis method

VD

= coefficient of variation for dead load

VI

= coefficient of variation for dynamic load allowance

VL

= coefficient of variation for live load

VR

= coefficient of variation for resistance

VS

= coefficient of variation for total load

Vf

= shear force at the ultimate limit state, N

Vp

= component in the direction of the applied shear of all of the effective prestressing forces crossing the critical section factored by φ p , the resistance factor for tendons in Clause 8.4.6 (taken as positive if resisting the applied shear), N

Vr

= factored shear resistance of a riveted joint, N

W

= gross vehicle weight, kN

αA

= load factors for force effects due to additional loads (including wind, creep, shrinkage, temperature, and differential settlement) that may be considered in the evaluation

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A

= load factors for force effects due to additional loads (including wind, creep, shrinkage, temperature, and differential settlement) that may be considered in the evaluation

D L   AD  AL D I L R

= load factors for force effects due to dead loads

µp

= ratio of area of prestressed reinforcement to area of concrete

 b

= reinforcement ratio of tensile reinforcement

A

= unfactored stress due to additional loads (including wind, creep, shrinkage, temperature, and differential settlement) that may be considered in the evaluation, MPa

D L  SLS  c  mc  md  mm r p

= unfactored dead load stress, MPa

= load factors for force effects due to live loads = target reliability index = bias coefficients (ratio of mean to nominal effects) for dead load analysis method = bias coefficients (ratio of mean to nominal effects) for live load analysis method = bias coefficients (ratio of mean to nominal effects) for dead load = bias coefficients (ratio of mean to nominal effects) for dynamic load allowance = bias coefficients (ratio of mean to nominal effects) for live load = bias coefficients (ratio of mean to nominal effects) for resistance

= reinforcement ratio producing balanced conditions — when the tension reinforcement reaches its yield strain just as the concrete compression reaches a strain of 0.0035 — used in the calculation of U

= unfactored live load stress, MPa = serviceability limit state stress, MPa = resistance factor = resistance factor for concrete (see Clause 8.4.6) = member resistance factor for a riveted connection = member resistance factor for a reinforced concrete deck slab = member resistance factor for a masonry component = material resistance factor for rivet steel = mechanical reinforcement ratio for prestressing steel

14.4 General requirements 14.4.1 Exclusions This Section shall not be used to determine whether a bridge or bridge design complies with the design requirements of Sections 1 to 13 and 16. Pedestrian bridges, railings, barrier walls, foundations, and retaining walls shall be evaluated in accordance with the design requirements of this Code. This Section does not address loads caused by earthquakes, fires, floods, ice, and vehicle and vessel collisions. This Section shall not be used unless the bridge is secure against causes of failure other than traffic loading. Loads other than traffic shall be considered in accordance with other Sections of this Code, except as required by Clause 14.9.5. This Section shall not be used for buried structures.

14.4.2 Expertise Evaluations in accordance with this Section shall be performed and checked by suitably qualified Engineers, and shall be reviewed by an experienced bridge Engineer, who may also be one of the persons performing or checking the evaluation.

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14.4.3 Future growth of traffic or future deterioration No allowance is made in this Section for future growth of traffic or for future deterioration of the bridge. If such changes are anticipated, they shall be considered in the evaluation. If any change in traffic or in the condition of the bridge that has not been accounted for occurs, the evaluation shall be reviewed and, if necessary, the bridge shall be re-evaluated. 

14.4.4 Scope of evaluation The scope of the evaluation shall be determined in consultation with the Owner, with particular care exercised for single load path structures with brittle failure modes.

14.5 Evaluation procedures 14.5.1 General The procedures in this Section shall be used when bridges are to be evaluated for load limit restrictions, serviceability, or fatigue loadings. A bridge shall be evaluated in accordance with one or more of the following methods: (a) ultimate limit states methods (except for masonry abutments, masonry piers, and masonry retaining walls). The following shall be considered acceptable methods: (i) ultimate limit states methods in accordance with Clauses 14.15.2.1 and 14.15.2.2, using load and resistance adjustment factors specified in Clauses 14.13 and 14.14; (ii) the mean load method for ultimate limit states specified in Clause 14.15.2.3; and (iii) the load testing method specified in Clause 14.16; (b) serviceability limit states methods; and (c) other Approved methods.

14.5.2 Limit states 

14.5.2.1 General The limit states for which a bridge is to be evaluated shall be selected from Clauses 14.5.2.2 to 14.5.2.4.

14.5.2.2 Ultimate limit states Ultimate limit states shall be used in determining the load-carrying capacity, stability, and load posting of bridges, except as specified in Clause 14.5.2.3. 

14.5.2.3 Serviceability limit states Serviceability limit states shall be used in determining the load-carrying capacity, stability, and load posting of masonry abutments, masonry piers, and masonry retaining walls, in accordance with Clause 14.15.3. For a bridge where cracking, deformation, stresses, or vibrations are detrimental to the structure, expected, or evident, the bridge and its affected components shall be evaluated for serviceability limit states requirements in accordance with the applicable Sections of this Code. Where there is no evidence of serviceability-related defects, the evaluation need not consider the serviceability limit state if neither the use nor the behaviour of the bridge is changed.

14.5.2.4 Fatigue limit state Evaluations for the fatigue limit state shall be carried out in accordance with Clause 14.18.

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14.5.2.5 — Deleted



14.5.3 — Deleted



14.5.4 Evaluation methodology



14.5.4.1 General

© Canadian Standards Association

The following requirements shall apply to the evaluation of bridges in accordance with this Section: (a) a condition inspection of the structure shall be conducted in accordance with Clause 14.6; (b) material strengths shall be determined in accordance with Clause 14.7; (c) loads shall be defined in accordance with Clauses 14.8 to 14.10; and (d) lateral distribution of live load shall be categorized in accordance with Clause 14.11.

14.5.4.2 Evaluation at ultimate limit states using load and resistance factors The following requirements shall apply to the evaluation at ultimate limit states using load and resistance factors: (a) the target reliability index,  , shall be selected in accordance with Clause 14.12.1; (b) the load factors shall be selected in accordance with Clause 14.13; (c) the resistances shall be calculated in accordance with Clause 14.14; and (d) the live load capacity factor, F, shall be determined in accordance with Clause 14.15.

14.5.4.3 Evaluation at serviceability limit states For evaluation at serviceability limit states, the live load capacity factor, F, shall be determined in accordance with Clause 14.15.3.

14.5.4.4 Evaluation by use of mean load method The following requirements shall apply to evaluation by use of the mean load method: (a) the target reliability index,  , shall be selected in accordance with Clause 14.12.1; (b) nominal (unfactored) resistances shall be calculated in accordance with Sections 6 to 12 or Clause 14.14 by taking all resistance factors,  , as having a value of 1.0; and (c) the live load capacity factor, F, shall be determined in accordance with Clause 14.15.2.3.

14.5.4.5 Evaluation by load testing The following requirements shall apply to evaluation by load testing: (a) the bridge shall be evaluated in accordance with Clause 14.5.4.2, 14.5.4.3, or 14.5.4.4; (b) the bridge shall be tested in accordance with Clause 14.16; and (c) the live load capacity factor, F, shall be determined in accordance with Clause 14.16.4.2.

14.5.5 Bridge posting If a bridge needs to be posted for load restriction based on the load capacity factor calculated in accordance with Clause 14.15 or 14.16, the posting loads shall be in accordance with Clause 14.17.

14.6 Condition inspection 14.6.1 General A condition inspection of the bridge shall be carried out to the satisfaction of the evaluator. Inspection records shall be sufficiently detailed to allow changes in condition to be assessed during future inspections.

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14.6.2 Plans The evaluator shall verify that the available Plans accurately represent the dimensions, member sizes, and other essential geometric features of the structure, for the original construction and subsequent rehabilitations and modifications. If no Plans are available, measurements shall be made with sufficient precision to suit the intended purpose.

14.6.3 Physical features All physical features of a bridge that affect its structural integrity shall be examined.

14.6.4 Deterioration All flawed, damaged, distorted, or deteriorated regions shall be identified, and sufficient data shall be collected so that these defects can be properly considered in the evaluation.

14.7 Material strengths 14.7.1 General The strengths of materials that do not have visible signs of deterioration shall be determined using one of the following methods: (a) review of Plans and other documents in accordance with Clause 14.7.2; (b) analysis of tests of samples obtained from the bridge or from specific bridge components in accordance with Clause 14.7.3; (c) estimation by considering the date of bridge construction in accordance with Clause 14.7.4; or (d) an Approved method.

14.7.2 Review of original construction documents 

14.7.2.1 General The Plans and other relevant contract documents may be reviewed to determine (a) the specified minimum yield strength of structural steel and structural aluminum; (b) the specified compressive strength of concrete; (c) the specified minimum yield strength of reinforcing steel; (d) the specified tensile strength of prestressing steel; (e) the species and grade of wood; and (f) the type of stone and grade of mortar used in masonry construction.

14.7.2.2 Mill certificates Actual values of yield and ultimate tensile stresses reported on mill certificates shall not be used for evaluation. Instead, the strength used shall be the guaranteed minimum value specified for the grade of steel shown on the certificate.

14.7.3 Analysis of tests of samples 14.7.3.1 General Nominal material strengths to be used in the calculation of member resistances may be determined by testing samples obtained from the bridge. Samples shall not be removed from locations where the strength, stability, or integrity of the member might be adversely affected. The location and orientation of each sample shall be recorded, as well as any additional information that could later be useful in interpretation of the test results.

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Material strength values obtained by testing shall not be directly substituted into the equations for resistance specified in this Code. Test results shall be converted to nominal material strengths in accordance with Annex A14.1 or an Approved method.

14.7.3.2 Prestressing steel Removal of prestressing steel specimens for testing shall not jeopardize the safety of the structure or be hazardous to the personnel involved. Specimens shall be tested in accordance with CSA G279.

14.7.3.3 Wood In lieu of obtaining wood samples for testing, the species and grade shall be identified by a wood grader.

14.7.3.4 Masonry mortar Mortar in joints shall be sampled or tested to obtain the compressive strength. The mortar shall be classified as one of the following types: (a) hard mortar — compressive strength greater than 7 MPa; (b) medium mortar — compressive strength between 2 and 7 MPa; or (c) soft mortar — compressive strength less than 2 MPa. The allowable limit state stress at the serviceability limit state in shear and compression shall be determined using a rational method based on the classification of the mortar, the thickness of the mortar joint, and the type of stone used in the masonry.

14.7.4 Strengths based on date of construction 14.7.4.1 General In the absence of more specific information, preliminary evaluation may be based on material strengths estimated by considering the date of bridge construction.

14.7.4.2 Structural steel If Plans and mill certificates are not available, and coupons have not been taken for testing, the values specified in Table 14.1 shall be used for structural steel.

Table 14.1 Properties of structural steel (See Clause 14.7.4.2.)

Date of bridge construction

Specified Fy , MPa

Specified Fu , MPa

Before 1905 1905–1932 1933–1975 After 1975

180 210 230 250

360 420 420 420

14.7.4.3 Concrete If Plans and specifications are not available and cores have not been obtained, the compressive strength of concrete with no visible signs of deterioration shall be taken as 15 MPa for the substructure, 20 MPa for the superstructure, and 25 MPa for prestressed concrete components.

14.7.4.4 Reinforcing steel If Plans and mill certificates are not available and specimens have not been tested, the values specified in Table 14.2 shall be used for reinforcing steel.

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© Canadian Standards Association

Table 14.2 Minimum yield strengths of reinforcing steel, MPa (See Clause 14.7.4.4.) Grade Date of bridge construction

Structural

Medium or intermediate

Hard

Unknown

Before 1914 1914–1972 1973–1978 After 1978

— 230 275 300

— 275 345 350

— 345 415 400

210 230 275 300

14.7.4.5 Prestressing steel If Plans and mill certificates are not available and specimens have not been tested, the tensile strength of prestressing steel shall be taken as 1600 MPa for bridges constructed before 1963 and 1725 MPa for bridges constructed later.

14.7.4.6 Rivets If Plans and mill certificates are not available, the following values for the ultimate tensile strength of rivets shall be used: (a) rivets constructed to ASTM A 7-39, constructed before 1936, or of unknown origin: Fu = 320 MPa; and (b) rivets constructed to CESA S42-1935, CSA G40.2-1959, ASTM A 141-33, ASTM A 141-39, or ASTM A 502-65, or constructed after 1935 but of unknown origin: Fu = 360 MPa.

14.7.5 Deteriorated material Deteriorated material shall be assessed in accordance with Clause 14.14.3. Non-destructive test methods, such as ultrasonic pulse velocity and surface hardness methods, may be used to correlate the concrete strength in damaged and sound regions of a structure. If compressive strengths are estimated using non-destructive methods, calibration factors shall be determined using concrete cores from the structure, and their uncertainty shall be accounted for in the estimate of predicted strengths.

14.8 Permanent loads 14.8.1 General The evaluation of the load-carrying capacity of existing bridges shall take into consideration all permanent loads except as specified in Clause 14.8.4.

14.8.2 Dead load 

14.8.2.1 General Dead load shall include the weight of all components of the bridge, fill, utilities, and other materials permanently on the bridge. Dead loads shall be determined from available Plans and verified with field measurements in accordance with Clause 14.6. Dead load shall be apportioned to three categories, D1, D2, and D3, as follows: (a) D1: dead load of factory-produced components and cast-in-place concrete, excluding decks; (b) D2: cast-in-place concrete decks (including voided decks and cementitious concrete overlays), wood, field-measured bituminous surfacing, and non-structural components; and (c) D3: bituminous surfacing where the nominal thickness is assumed to be 90 mm for the evaluation. May 2010 (Replaces p. 651, November 2006)

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14.8.2.2 Dead load distribution The transverse distribution of dead load shall be in accordance with Section 5.

14.8.3 Earth pressure and hydrostatic pressure Earth pressure and hydrostatic pressure shall be considered in the evaluation, treated as permanent loads, and multiplied by a load factor in accordance with Clause 14.13.2.2.

14.8.4 Shrinkage, creep, differential settlement, and bearing friction Shrinkage, creep, differential settlement, and bearing friction need not be considered in evaluation at ultimate limit states if their effects induce ductile behaviour. When their effects induce non-ductile behaviour, they shall have load factors determined in accordance with Clause 14.13.2.3.

14.8.5 Secondary effects from prestressing Secondary effects from prestressing shall be considered as permanent loads and multiplied by load factors in accordance with Clause 3.5.1.

14.9 Transitory loads 14.9.1 Normal traffic 14.9.1.1 General Bridges shall be evaluated for the following: (a) a vehicle train, a two-unit vehicle, and a single-unit vehicle, as specified in Clause 14.9.1.2, 14.9.1.3, and 14.9.1.4, respectively; or (b) alternative loading based on local traffic, as specified in Clause 14.9.1.6. Truck axles and portions of uniformly distributed lane load that reduce the load effect shall be neglected.

14.9.1.2 Evaluation Level 1 (vehicle trains) A bridge required to carry vehicle trains in normal traffic shall be evaluated to Evaluation Level 1, for which the live load model shall be the CL1-W Truck or Lane Load shown in Figure 14.1, where W is the gross vehicle weight in kilonewtons of a vehicle train legally permitted on bridges without a permit. The value of W shall be taken as 625 unless the Regulatory Authority uses lesser or greater values of W where traffic conditions are expected to differ from the norm. In Ontario, the load used for Evaluation Level 1 shall be the CL1-625-ONT Truck Load or CL1-625-ONT Lane Load specified in Annex A14.2.

14.9.1.3 Evaluation Level 2 (two-unit vehicles) A bridge shall be evaluated to Evaluation Level 2 when load restrictions are to be applied and the bridge is required to carry two-unit vehicles. The live load model shall be the CL2-W Truck or Lane Load shown in Figure 14.2, where W is as specified in Clause 14.9.1.2. In Ontario, the load used for Evaluation Level 2 shall be the CL2-625-ONT Truck Load or the CL2-625-ONT Lane Load specified in Annex A14.3.

14.9.1.4 Evaluation Level 3 (single-unit vehicles) A bridge shall be evaluated to Evaluation Level 3 when load restrictions are to be applied and the bridge is required to carry single-unit vehicles. The live load model shall be the CL3-W Truck or Lane Load shown in Figure 14.3, where W is as specified in Clause 14.9.1.2. In Ontario, the load used for Evaluation Level 3 shall be the CL3-625-ONT Truck Load or the CL3-625-ONT Lane Load specified in Annex A14.4.

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© Canadian Standards Association

Axle No. Axle load Wheel load

Canadian Highway Bridge Design Code

2 3 0.2W 0.2W 0.1W 0.1W

1 0.08W 0.04W

4 0.28W 0.14W

5 0.24W 0.12W Gross load = 1.00W

3.6 m

1.2 m

6.6 m

6.6 m

18 m

1.8 m

0.6 m (typ.)

CL Wheel

Travel

0.25 m (typ.)

0.25 m (typ.)

0.25 m (typ.)

3.0 m truck width

CL Axle (typical)

CL Wheel

CL1-W Truck Load (elevation)

0.6 m (typ.)

CL1-W Truck Load (plan)

Axle load

0.064W

0.160W 0.160W

0.224W

0.192W q

3.6 m

1.2 m

6.6 m

6.6 m

18 m

CL1-W Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure 14.1 Level 1 evaluation loads with CL1-W Truck (See Clauses 14.9.1.2 and 14.9.1.7.)

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Axle No. Axle load Wheel load

4 0.28W 0.14W

2 3 0.20W 0.20W 0.10W 0.10W

1 0.08W 0.04W

Gross load = 0.76W 3.6 m

1.2 m

6.6 m

11.4 m

C Axle (typical) L

Travel

0.25 m (typ.)

C Wheel L

0.6 m (typ.)

0.25 m (typ.)

0.25 m (typ.)

3.0 m truck width

1.8 m

C Wheel L

CL2-W Truck Load (elevation)

0.6 m (typ.)

CL2-W Truck Load (plan)

Axle load

0.064W

0.160W 0.160W

0.224W q

3.6 m

1.2 m

6.6 m

11.4 m

CL2-W Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure 14.2 Level 2 evaluation loads with CL2-W Truck (See Clauses 14.9.1.3 and 14.9.1.7.)

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Axle No. Axle load Wheel load

Canadian Highway Bridge Design Code

3 2 0.20W 0.20W 0.10W 0.10W

1 0.08W 0.04W

Gross load = 0.48W 3.6 m

1.2 m

4.8 m

C Axle (typical) L

1.8 m

Travel

0.25 m (typ.)

C Wheel L

0.6 m (typ.)

0.6 m (typ.)

0.25 m (typ.)

0.25 m (typ.)

3.0 m truck width

C Wheel L

CL3-W Truck Load (elevation)

CL3-W Truck Load (plan) Axle load

0.064W

0.160W 0.160W q 3.6 m

1.2 m

4.8 m

CL3-W Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure 14.3 Level 3 evaluation loads with CL3-W Truck (See Clauses 14.9.1.4 and 14.9.1.7.)

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14.9.1.5 Configuration of evaluation load models The wheel spacings, wheel footprints, and clearances of the Evaluation Level 1, 2, and 3 Trucks shall be as specified in Clause 14.9.1.2, 14.9.1.3, and 14.9.1.4, respectively. The uniformly distributed load in a lane load shall occupy a width of 3.0 m in a traffic lane.

14.9.1.6 Alternative loading As an alternative to the CL1-W, CL2-W, and CL3-W loadings in Clauses 14.9.1.2 to 14.9.1.4, the traffic load for evaluation may be based on local vehicle and traffic conditions. The load factor, α L , to be used with the alternative loading shall be in accordance with Table 14.9. The alternative loading to be used for evaluation shall be the more severe of (a) the vehicle for which the bridge is being evaluated, with dynamic load allowance in accordance with Clause 3.8.4.5; or (b) 80% of the vehicle for which the bridge is being evaluated, plus a superimposed uniformly distributed load of 9, 8, 7, and 7 kN/m for highway classes A, B, C, and D, respectively, without dynamic load allowance for either vehicle or uniformly distributed loads.

14.9.1.7 Dynamic load allowance for normal traffic For the Truck models shown in Figures 14.1 to 14.3, A14.2.1, A14.3.1, and A14.4.1, the dynamic load allowance shall be in accordance with Clause 3.8.4.5. For the Lane Load models shown in Figures 14.1 to 14.3, A14.2.1, A14.3.1, and A14.4.1, no dynamic load allowance shall be applied to the Truck or the uniformly distributed load.

14.9.2 Permit — Vehicle loads 14.9.2.1 General Vehicles operating under permit shall be classified as PA, PB, PC, or PS in accordance with Clauses 14.9.2.2 to 14.9.2.5.

14.9.2.2 Permit — Annual or project (PA) PA traffic shall include the vehicles authorized by permit on an annual basis or for the duration of a specific project to carry an indivisible load, mixed with other traffic without supervision. Individual axle loads and the gross vehicle weight may exceed the non-permit legislated limits. For the lane carrying the PA vehicle, the load effect shall be calculated from the more severe of (a) the permit vehicle alone in the lane with dynamic load allowance, in accordance with Clause 14.9.3; or (b) 85% of the permit vehicle, plus a superimposed uniformly distributed load of 9, 8, 7, and 7 kN/m for highway classes A, B, C, and D, respectively, without dynamic load allowance for either Truck or uniformly distributed loads.

14.9.2.3 Permit — Bulk haul (PB) PB traffic shall include bulk haul divisible load traffic authorized by permit programs for many trips, mixed with general traffic. Axle loads shall not exceed the non-permit legislated limits, but gross vehicle weights may exceed such limits. Axle spacings may be less than the legislated limits. Permit limits on axle loads and gross vehicle weights shall be strictly enforced. For the lane carrying the PB vehicle, the load effect shall be calculated from the more severe of (a) the permit vehicle alone in the lane with dynamic load allowance, in accordance with Clause 14.9.3; or (b) 80% of the permit vehicle, plus a superimposed uniformly distributed load of 9, 8, 7, and 7 kN/m for highway classes A, B, C, and D, respectively, without dynamic load allowance for either Truck or uniformly distributed loads.

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14.9.2.4 Permit — Controlled (PC) PC traffic shall include the vehicles authorized by permit to carry an indivisible load on a specified route under supervision and specified travel conditions. The weights and spacings of the axles shall be verified by measurement. Lane load need not be considered for PC traffic if other traffic is excluded from the bridge during passage of the PC vehicle.

14.9.2.5 Permit — Single trip (PS) PS traffic shall include vehicles authorized by permit for a single trip to carry an indivisible load, mixed with other traffic without supervision. Axle loads and the gross vehicle weight may exceed the non-permit legislated limits. For the lane carrying the PS vehicle, the load effect shall be calculated from the more severe of (a) the permit vehicle alone in the lane with dynamic load allowance, in accordance with Clause 14.9.3; or (b) 85% of the permit vehicle, plus a superimposed uniformly distributed load of 9, 8, 7, and 7 kN/m for highway classes A, B, C, and D, respectively, without dynamic load allowance for either Truck or uniformly distributed loads. 

14.9.3 Dynamic load allowance for permit vehicle loads and alternative loading The dynamic load allowance for permit vehicle loads shall be as specified in Clause 3.8.4.5, except the dynamic load allowance specified in Clause 3.8.4.5.3(c) shall be taken as 0.30 for tandems, tridems, two-axle groups, and the axle group consisting of the front axle and drive axles. For a permit vehicle crossing the bridge at a restricted speed, the dynamic load allowance so calculated shall be multiplied by (a) 0.30 for a vehicle speed of 10 km/h or less; (b) 0.50 for a vehicle speed greater than 10 km/h and less than or equal to 25 km/h; (c) 0.75 for a vehicle speed greater than 25 km/h and less than or equal to 40 km/h; and (d) 1.00 for a vehicle speed greater than 40 km/h.

14.9.4 Multiple-lane loading 14.9.4.1 Design lanes The number of loaded lanes shall be determined in accordance with the current or intended use of the bridge. Where the traffic lanes are clearly designated on the bridge, they shall be used as design lanes, except that outer lanes shall include the adjacent shoulders.

14.9.4.2 Normal traffic The modification factors for multiple-lane loading shall be as specified in Table 14.3.

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Table 14.3 Modification factors for multiple-lane loading (See Clause 14.9.4.2.) Highway class Number of lanes loaded

A

B

C or D

1 2 3 4 5 6 or more

1.00 0.90 0.80 0.70 0.60 0.55

1.00 0.90 0.80 0.70 — —

1.00 0.85 0.70 — — —

14.9.4.3 Permit vehicle with normal traffic When the permit vehicle is allowed to travel with normal traffic, the loading to be applied in the other lanes shall be taken as a fraction of the CL1-W loading or CL1-625-ONT loading, as specified in Table 14.4.

Table 14.4 Fraction of CL1-W loading to be applied in the other lanes (See Clause 14.9.4.3.) Highway class

Second loaded lane Third and subsequent loaded lanes

A

B

C or D

0.7 0.4

0.6 0.4

0.5 0.4

14.9.5 Loads other than traffic 14.9.5.1 Sidewalk loading Except for sidewalk components, sidewalk loading shall not be considered coincident with traffic loading unless the evaluator has reason to suppose that significant sidewalk loading will occur coincident with maximum traffic loading, in which case the pedestrian loading specified in Clause 3.8.9 shall be used with the same load factor specified in Clause 14.13.3 for traffic.

14.9.5.2 Snow loads If significant snow loading on sidewalks is expected, it shall be considered in the evaluation.

14.9.5.3 Wind loads Wind loads are not specifically considered in this Section. If the evaluator considers that significant wind forces could occur simultaneously with the maximum traffic loads, these wind forces shall be considered in accordance with Clause 3.10.

14.9.5.4 Temperature effects Temperature effects need not be considered at ultimate limit states for any element that will behave in a ductile manner. When non-ductile behaviour is expected, temperature effects shall be considered in accordance with Clause 3.9.4.

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14.9.5.5 Secondary effects Secondary effects (excluding secondary effects from prestressing) need not be considered in evaluation at ultimate limit states if their effects induce ductile behaviour. When secondary effects induce non-ductile behaviour, they shall be considered and multiplied by a load factor in accordance with Clause 3.5.1. 

14.9.5.6 — Deleted

14.10 Exceptional loads Loads (other than traffic loads) that occur on rare occasions and are of significant magnitude shall be considered exceptional loads and shall be evaluated in accordance with Sections 1 to 13 and 16 or, when not covered by Sections 1 to 13 and 16, in accordance with good engineering practice.

14.11 Lateral distribution categories for live load 14.11.1 General The method to be used in calculating the lateral distribution of live loads to the elements considered shall be categorized as statically determinate, sophisticated, or simplified in accordance with Clauses 14.11.2 to 14.11.4.

14.11.2 Statically determinate method In this method the lateral distribution is statically determinate.

14.11.3 Sophisticated method In this method the lateral distribution is statically indeterminate and is calculated in accordance with a sophisticated method of analysis such as the grillage analogy, orthotropic plate theory, finite element, finite strip, or folded plate method.

14.11.4 Simplified method In this method the lateral distribution is calculated in accordance with the simplified methods of Section 5. However, it is possible that the methods specified in Section 5 will not be suitable for non-standard bridges or permit vehicle loads (especially those that are wider than the CL-W vehicles), in which cases such methods shall not be used.

14.12 Target reliability index 14.12.1 General

For all evaluation levels, the target reliability index,  , shall be taken from Table 14.5 for PA, PB, and PS traffic and Table 14.6 for PC traffic. In both cases, the system behaviour, element behaviour, and inspection level shall be as specified in Clauses 14.12.2 to 14.12.4.

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14.12.2 System behaviour System behaviour shall take into consideration the effect of any existing deterioration and shall be classified into one of the following categories: (a) Category S1, where element failure leads to total collapse. This includes failure of main members with no benefit from continuity or multiple-load paths, e.g., a simply supported girder in a two-girder system. (b) Category S2, where element failure probably will not lead to total collapse. This includes main load-carrying members in a multi-girder system or continuous main members in bending. (c) Category S3, where element failure leads to local failure only. This includes deck slabs, stringers, and bearings in compression.

14.12.3 Element behaviour Element behaviour shall take into consideration the effect of any existing deterioration and shall be classified into one of the following categories: (a) Category E1, where the element being considered is subject to sudden loss of capacity with little or no warning. This can include failure by buckling, concrete in shear and/or torsion with less than the minimum reinforcement required by Clause 14.14.1.6.2(a), bond (pullout) failure, suspension cables, eyebars, bearing stiffeners, over-reinforced concrete beams, connections, concrete beam-column compression failure, and steel in tension at net section. (b) Category E2, where the element being considered is subject to sudden failure with little or no warning but will retain post-failure capacity. This can include concrete in shear and/or torsion with at least the minimum reinforcement required by Clause 14.14.1.6.2(a), and steel plates in compression with post-buckling capacity. (c) Category E3, where the element being considered is subject to gradual failure with warning of probable failure. This can include steel beams in bending or shear, under-reinforced concrete in bending, decks, and steel in tension at gross section.

14.12.4 Inspection level Evaluation shall not be undertaken without inspection. Inspection levels shall be classified as follows: (a) Inspection Level INSP1, where a component is not inspectable. This can include hidden members not accessible for inspection, e.g., interior webs of adjacent box beams. (b) Inspection Level INSP2, where inspection is to the satisfaction of the evaluator, with the results of each inspection recorded and available to the evaluator. (c) Inspection Level INSP3, where the evaluator has directed the inspection of all critical and substandard components and final evaluation calculations account for all information obtained during this inspection.

14.12.5 Important structures For structures that can affect the life or safety of people under or near a bridge, are essential to the local economy, or are designated as emergency route bridges (in accordance with Clause 4.4.2), a value of  greater than that specified in Table 14.5 or 14.6 shall be used if directed by the Regulatory Authority.

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Canadian Highway Bridge Design Code

Table 14.5 Target reliability index, β , for normal traffic and for PA, PB, and PS traffic (See Clauses 14.12.1 and 14.12.5.) System behaviour category

Element behaviour category

Inspection level INSP1

INSP2

INSP3

S1

E1 E2 E3

4.00 3.75 3.50

3.75 3.50 3.25

3.75 3.25 3.00

S2

E1 E2 E3

3.75 3.50 3.25

3.50 3.25 3.00

3.50 3.00 2.75

S3

E1 E2 E3

3.50 3.25 3.00

3.25 3.00 2.75

3.25 2.75 2.50

Table 14.6 Target reliability index, β , for PC traffic (See Clauses 14.12.1 and 14.12.5.) System behaviour category

Element behaviour category

Inspection level INSP1

INSP2

INSP3

S1

E1 E2 E3

3.50 3.25 3.00

3.25 3.00 2.75

3.25 2.75 2.50

S2

E1 E2 E3

3.25 3.00 2.75

3.00 2.75 2.50

3.00 2.50 2.25

S3

E1 E2 E3

3.00 2.75 2.50

2.75 2.50 2.25

2.75 2.25 2.00

14.13 Load factors 14.13.1 General The unfactored load effects for each element under consideration shall be multiplied by the appropriate load factors specified in Clauses 14.13.2 and 14.13.3 for the value of β determined in accordance with Clause 14.12 for the element under consideration.

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14.13.2 Permanent loads 14.13.2.1 Dead load When the dead load effect counteracts the effect due to transitory load, the minimum dead load factors specified in Section 3 shall be used for all dead load categories at any β value. Otherwise, the dead load factors specified in Table 14.7 shall apply.

Table 14.7 Maximum dead load factors, α D (See Clause 14.13.2.1.) Target Reliability Index, β Dead load category

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

D1 D2 D3

1.03 1.06 1.15

1.04 1.08 1.20

1.05 1.10 1.25

1.06 1.12 1.30

1.07 1.14 1.35

1.08 1.16 1.40

1.09 1.18 1.45

1.10 1.20 1.50

1.11 1.22 1.55

14.13.2.2 Earth pressure and hydrostatic pressure The load factors for earth pressure and hydrostatic pressure shall be in accordance with Clause 3.5.1.

14.13.2.3 Temperature, shrinkage, creep, differential settlement, and bearing friction If consideration of temperature, shrinkage, creep, differential settlement, or bearing friction is required by Clause 14.8.4 or 14.9.5.4, the load factors shall be in accordance with Clause 3.5.1.

14.13.2.4 Secondary effects from prestressing The load factors for secondary effects from prestressing shall be in accordance with Clause 14.9.5.5.

14.13.3 Transitory loads 14.13.3.1 Normal traffic The live load factors for normal traffic Evaluation Levels 1, 2, and 3 shall be as specified in Table 14.8. The live load factors for alternative loading as specified in Clause 14.9.1.6 shall be as specified in Table 14.9. For Table 14.9, “Short span” load factors shall be used for shear effects in beams with a span up to 6 m, moment effects in beams with a span up to 10 m, and shears and moments in floor beams where the tributary spans are up to 6 m. For all other conditions, “Other span” load factors shall be used.

Table 14.8 Live load factors, α L, for normal traffic (Evaluation Levels 1, 2, and 3) for all types of analysis (See Clause 14.13.3.1.) Target reliability index, β

662

Spans

2.50

2.75

3.00

3.25

3.50

3.75

4.00

All Spans

1.35

1.42

1.49

1.56

1.63

1.70

1.77

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Canadian Highway Bridge Design Code

Table 14.9 Live load factors, α L, for normal traffic (alternative loading) for all types of analysis (See Clauses 14.9.1.6 and 14.13.3.1.) Target reliability index, β Spans

2.50

2.75

3.00

3.25

3.50

3.75

4.00

Short spans Other spans

1.80 1.35

1.90 1.42

2.00 1.49

2.10 1.56

2.20 1.63

2.30 1.70

2.40 1.77

14.13.3.2 Permit vehicle loads The live load factors for permit vehicles shall be as specified in Tables 14.10 to 14.13, with “Short spans” and “Other spans” as specified in Clause 14.13.3.1.

Table 14.10 Live load factors, α L, for PA traffic (See Clause 14.13.3.2.) Target reliability index, β

Type of analysis

Spans

2.50

2.75

3.00

3.25

3.50

3.75

4.00

Statically determinate

Short spans Other spans

1.42 1.27

1.48 1.32

1.53 1.37

1.59 1.42

1.65 1.48

1.71 1.53

1.77 1.59

Sophisticated

Short spans Other spans

1.45 1.29

1.51 1.34

1.58 1.39

1.64 1.45

1.71 1.51

1.78 1.57

1.85 1.63

Simplified (Section 5)

Short spans Other spans

1.48 1.28

1.55 1.34

1.62 1.40

1.70 1.47

1.78 1.53

1.87 1.60

1.96 1.67

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Table 14.11 Live load factors, α L, for PB traffic (See Clause 14.13.3.2.) Target reliability index, β

Type of analysis

Spans

2.50

2.75

3.00

3.25

3.50

3.75

4.00

Statically determinate

Short spans Other spans

1.15 1.10

1.19 1.12

1.23 1.16

1.28 1.21

1.33 1.26

1.38 1.30

1.43 1.36

Sophisticated

Short spans Other spans

1.17 1.10

1.22 1.13

1.27 1.18

1.32 1.23

1.38 1.28

1.43 1.33

1.49 1.39

Simplified (Section 5)

Short spans Other spans

1.19 1.10

1.25 1.13

1.31 1.19

1.37 1.24

1.44 1.30

1.50 1.36

1.57 1.42

Table 14.12 Live load factors, α L, for PC traffic (See Clause 14.13.3.2.) Target reliability index, β

Type of analysis

Spans

2.00

2.25

2.50

2.75

3.00

3.25

3.50

Statically determinate

Short spans Other spans

1.11 1.10

1.15 1.10

1.19 1.10

1.24 1.13

1.28 1.18

1.33 1.23

1.38 1.28

Sophisticated

Short spans Other spans

1.12 1.10

1.17 1.10

1.22 1.10

1.27 1.14

1.32 1.19

1.37 1.24

1.43 1.30

Simplified (Section 5)

Short spans Other spans

1.13 1.10

1.18 1.10

1.24 1.10

1.30 1.13

1.36 1.19

1.42 1.25

1.49 1.31

Table 14.13 Live load factors, α L, for PS traffic (See Clause 14.13.3.2.)

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Target reliability index, β

Type of analysis

Spans

2.50

2.75

3.00

3.25

3.50

3.75

4.00

Statically determinate

Short spans Other spans

1.34 1.20

1.39 1.24

1.44 1.29

1.49 1.34

1.55 1.39

1.61 1.44

1.67 1.50

Sophisticated

Short spans Other spans

1.36 1.21

1.42 1.26

1.48 1.31

1.54 1.36

1.60 1.42

1.67 1.48

1.74 1.54

Simplified (Section 5)

Short spans Other spans

1.38 1.20

1.45 1.26

1.52 1.32

1.60 1.38

1.67 1.44

1.75 1.51

1.84 1.57

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Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

14.14 Resistance 14.14.1 General 14.14.1.1 General The factored resistances of concrete, structural steel, and wood components shall be determined in accordance with the applicable Sections of this Code. Components that do not meet the limitations on which the resistance calculations of this Code are based shall have their resistances calculated in accordance with alternative procedures based on established and generally recognized theories, analyses, and engineering judgment.

14.14.1.2 Prestressed concrete using stress-relieved strand or wire 14.14.1.2.1 General The requirements of Section 8 for low-relaxation strand or wire shall be followed for the evaluation of prestressed concrete bridges using stress-relieved strand or wire, except as modified by Clauses 14.14.1.2.2 to 14.14.1.2.4.

14.14.1.2.2 Prestressing steel stress limitations Stresses at jacking or transfer shall be based on data given on the Plans. In the absence of such data, the following stress limitations, for both pretensioning and post-tensioning, shall be used: (a) at jacking: 0.80fpu ; and (b) at transfer: 0.70fpu .

14.14.1.2.3 Loss of prestress 14.14.1.2.3.1 At transfer In pretensioned components, the relaxation loss in prestressing steel, REL1, initially stressed in excess of 0.5fpu shall be calculated as follows:

REL1 =

⎤ log ( 24t ) ⎡ fsj − 0.55⎥ fsj ⎢ 10 ⎢⎣ fpy ⎥⎦

14.14.1.2.3.2 After transfer The loss of prestress due to relaxation after transfer, REL2 , shall be calculated as follows:

⎡⎡ f ⎤⎡ CR + SH ⎤ ⎤ REL2 = ⎢ ⎢ st − 0.52⎥ ⎢0.42 − ⎥ ⎥ fpu ≥ 0.01fpu 1.25fpu ⎥⎦ ⎥ ⎢⎣ ⎢⎣ fpu ⎥⎦ ⎢⎣ ⎦

14.14.1.2.4 Prestressing steel stress at the ultimate limit state The steel stress, fps , at the ultimate limit state in bonded prestressing steel shall be calculated using a method based on sectional strain compatibility and using stress-strain curves representative of the steel, except that if fse  0.5fpu , the value of fps may be calculated as follows:

m p fpu ⎤ ⎡ fps = fpu ⎢1− 0.5 ⎥ fc′ ⎦ ⎣

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14.14.1.3 Concrete deck slabs 

14.14.1.3.1 General When the concrete deck slab is at least 175 mm thick and the requirements for the empirical design method in accordance with Clause 8.18.4 are satisfied, the deck slab shall be deemed to have adequate resistance for the CL loadings specified with a value of W not greater than 625 kN in Clauses 14.9.1.2 to 14.9.1.4. When the concrete deck slab is less than 175 mm thick, W is greater than 625 kN, or the requirements of Clause 8.18.4 are not satisfied, an evaluation of the deck slab shall be carried out in accordance with Clauses 14.14.1.3.2 and 14.14.1.3.3.



14.14.1.3.2 Method of analysis If all of the conditions specified in Items (a) to (e) are satisfied, the factored resistance shall be determined in accordance with the simplified method specified in Clause 14.14.1.3.3; otherwise, the resistance shall be determined in accordance with Section 8 and expressed as an equivalent wheel load: (a) the centre-to-centre spacing of the supporting beams for a slab panel does not exceed 4.5 m and the slab extends sufficiently beyond the external beams to provide full development length for the bottom transverse reinforcement; (b) the ratio of the spacing of the supporting beams to the thickness of the slab does not exceed 20; (c) the minimum slab thickness of sound concrete is at least 150 mm (with the minimum slab thickness used for slabs of variable thickness); (d) all cross-frames or diaphragms extend throughout the cross-section of the bridge between external girders and the maximum spacing of such cross-frames or diaphragms is in accordance with Clause 8.18.5; and (e) edge stiffening is in accordance with Clause 8.18.6.

14.14.1.3.3 Simplified method If all of the conditions of Clause 14.14.1.3.2 are satisfied, the value of the factored resistance, Rr , shall be calculated as follows: Rr =  md Rn where

 md

= 0.5

The values of Rn for both composite and non-composite concrete deck slabs shall be calculated as follows: Rn = Rd Fq Fc where Rd is taken from Figure 14.4 or 14.5, as applicable, for the deck thickness, d, and the deck span being considered; Fq is a correction factor based on q, where q = 50 (As/bd + Ast /bdt ); and Fc is a correction factor based on fc’. The values of Fq and Fc shall be taken from Figure 14.4 or 14.5, as applicable, or obtained from those figures by linear interpolation. For deck thicknesses other than those shown in Figures 14.4 and 14.5, the value of Rn shall be obtained by linear interpolation.

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Canadian Highway Bridge Design Code

2200 t = 250 mm

2000

t = 225 mm

1500

t = 200 mm

Rd, kN

t = 175 mm 1000

t = 150 mm Correction factors

500

500

0

q

Fq

fc’

Fc

0.2 0.4 0.6 0.8 1.0

0.85 0.92 1.00 1.08 1.13

20 30 35 40

0.83 1.00 1.18 1.36

1.0

2.0

3.0

4.0 5.0

Span, m

Figure 14.4 Deck punching shear for composite slabs (See Clause 14.4.1.3.3.)

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2000 Correction factors

t = 250 mm

1500

q

Fq

fc’

Fc

0.2 0.4 0.6 0.8 1.0

0.70 0.87 1.00 1.10 1.21

20 30 35 40

0.87 1.00 1.17 1.38

Rd, kN

t = 225 mm t = 200 mm 1000 t = 175 mm t = 150 mm 500

0

0

1.0

2.0

3.0

4.0 5.0

Span, m

Figure 14.5 Deck punching shear for non-composite slabs (See Clause 14.14.1.3.3.)

14.14.1.4 Rivets 14.14.1.4.1 Rivets in tension The factored tensile resistance, Tr , of a riveted joint in tension shall be taken as Tr = φ r nAr Fu where Fu

= specified tensile strength of the rivet steel

φr

= 0.67

Rivets shall be able to resist the sum of the external load and any additional tensile load caused by deformation of the connected parts.

14.14.1.4.2 Rivets in shear The factored resistance of a riveted connection subject to shear shall be taken as the lesser of the following: (a) the factored bearing resistance, Br , calculated as follows: Br = φ mc tneFu ≤ 3φ mc tndFu

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where Fu

= smaller of the specified tensile strengths of the connected parts

φ mc

= 0.67

(b) the factored shear resistance, Vr , calculated as follows: = 0.75φr nmAr Fu

Vr where Fu

= specified tensile strength of the rivet steel

φr

= 0.67

14.14.1.4.3 Rivets in shear and tension A rivet that is required to develop resistance simultaneously to a tensile force and a shear force that result from loads at the ultimate limit state shall satisfy the following relationship: Vr2 + 0.56Tf2 ≤ 0.56(φ r Ar Fu)2 where Fu

= specified tensile strength of the rivet steel

φr

= 0.67

14.14.1.5 Masonry The unfactored resistance, Pn , of a masonry arch shall be calculated as the axle load that alone or in combination with other axle loads results in the minimum value of resistance of the arch based on a mechanism analysis of the arch. The passive resistance of the fill within the spandrel shall be taken into account in the analysis. The factored resistance, Pr , of a masonry arch shall be calculated as follows: Pr = φ mmPn The value of φ mm shall be taken as 0.80. However, for arches with soft mortar in the joints and in which the joint width exceeds 5% of the stone depth, φ mm shall be taken as 0.70.

14.14.1.6 Shear in concrete beams 14.14.1.6.1 General Concrete beams shall have their shear resistance calculated in accordance with Clause 8.9.3, except as modified in Clauses 14.14.1.6.2 and 14.14.1.6.3.

14.14.1.6.2 Transverse reinforcement area and spacing In lieu of the requirements of Clauses 8.9.1.3 and 8.14.6, the following transverse reinforcement requirements shall apply for use in Clauses 8.9.3.6 and 8.9.3.7: (a) The section shall have the shear resistance calculated as a section satisfying the minimum transverse reinforcement if (i)

A v ≥ 0.15fcr

(bv s ) ; fy

(ii) s ≤ sm1, where sm1 is obtained from Figure 14.6; and (iii) s/dv < sr1, where sr1 is obtained from Figure 14.7.

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(b) The section shall have the shear resistance calculated as a section with no transverse reinforcement if (i)

A v ≤ 0.05fcr

(bv s ) ; fy

(ii) s ≥ sm2, where sm2 is obtained from Figure 14.6; or (iii) s/dv ≥ sr2, where sr2 is obtained from Figure 14.7. (c) The section shall have the shear resistance calculated by linear interpolation of the shear resistances obtained from Items (a) and (b) if (i)

A v ≥ 0.05fcr

(bv s ) ;

fy (ii) s ≤ sm2, where sm2 is obtained from Figure 14.6; and (iii) s/dv ≤ sr2, where sr2 is obtained from Figure 14.7. The interpolation shall be based on the most severe of Av between 0.15 and 0.05, s between sm1 and sm2 , and s/dv between sr1 and sr2. 900 sm2

800 700

sm1

Spacing, mm

600 500 400 300 200 100 0

0

0.1

0.2

0.3

0.4

(Vf – Vp) /(fc bv dv f’c )

Figure 14.6 Spacing requirements for minimum reinforcement, mm (See Clause 14.14.1.6.2.)

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0.9 sr2

Spacing as a fraction of dv

0.8

sr1

0.7

0.75 0.6 0.5 0.4 0.3

0.33 0.2 0.1 0

0

0.1

0.2

0.3

0.4

(Vf – Vp) /(fc bv dv f’c )

Figure 14.7 Spacing requirements for minimum reinforcement as a fraction of shear depth (See Clause 14.14.1.6.2.)

14.14.1.6.3 Proportioning of transverse reinforcement 14.14.1.6.3.1 General For the purpose of evaluation, Clause 14.14.1.6.3.2 shall apply in lieu of Clause 8.9.3.9.

14.14.1.6.3.2 Amount of transverse reinforcement Provided that the cross-section does not change abruptly within a length equal to the member depth, h, and the load is applied through the top face of the beam, the amount of transverse reinforcement, Av h/s, may be taken as the total amount calculated within the length h. This length shall be measured from the section of interest toward the support.

14.14.1.7 Wood 14.14.1.7.1 General The resistances for beam and stringer grade and post and timber grade wood members of Select Structural Grade and Grade 1 quality shall be determined in accordance with Clauses 14.14.1.7.2 and 14.14.1.7.3. All other wood resistances shall be determined in accordance with Section 9.

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14.14.1.7.2 Shear The shear resistance in wood shall be taken from Clause 9.7, with fv u taken from Table 14.14 and the size effect factor, ksv , taken as follows:

ksv =

75

1 ≤ 2.5 d (1+ 2a / d )

where d

= member depth

For members older than five years, a shall be the distance measured from the centreline of the support to the tip of the end split. Where the split does not extend past the centreline of the support into the span, a shall be taken as zero. For members that are not older than five years, or where the end split length has not been measured, a shall be assumed to be 0.33d for Select Structural Grade and 0.75d for Grade 1.

14.14.1.7.3 Specified strengths and moduli of elasticity The specified strengths and moduli of elasticity shall be obtained from Table 14.14. 

Table 14.14 Specified strengths and moduli of elasticity for beam and stringer grades and post and timber grades, MPa (See Clauses 14.14.1.7.2 and 14.14.1.7.3.) Tension Modulus  Bending  Compression Compression  parallel of elasticity Species at extreme Longitudinal  parallel  perpendicular  to grain, Combination Grade fibre, ƒbu shear, ƒvu E05 to grain, ƒpu to grain, ƒqu ƒtu E50 Douglas fir– Larch

SS No. 1

24.0 20.0

1.1 1.1

16.5 10.0

4.7 4.7

13.0 9.0

11 000 9 500

7 500 6 500

Hem-Fir

SS No. 1

20.0 18.0

0.8 0.8

14.5 10.5

3.1 3.1

13.0 9.0

11 000 10 500

7 500 7 000

Spruce- Pine-Fir

SS No. 1

18.5 13.0

1.0 1.0

14.5 10.5

3.6 3.6

13.0 9.0

10 000 9 000

7 000 6 000

Northern  species

SS No. 1

13.0 10.8

0.8 0.8

10.0 7.0

2.3 2.3

10.0 7.0

7 000 6 000

5 000 4 000

Note: See Clause 9.3 for the symbols used in this Table.

14.14.1.8 Shear in steel plate girders with intermediate transverse stiffeners Clauses 10.10.5 and 10.10.6 shall be used to calculate the shear resistance of steel plate girders with intermediate transverse stiffener plates on one side of the web if the width-to-thickness ratio of the plate does not exceed 400/ Fy .

14.14.2 Resistance adjustment factor For all components that have no visible sign of defect or deterioration, the factored resistance, as calculated in accordance with Clause 14.14.1, shall be multiplied by the appropriate resistance adjustment factor, U, specified in Table 14.15. Where no value for U is specified in Table 14.15 and in lieu of better information, a value of U = 1.0 may be used.

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Canadian Highway Bridge Design Code

14.14.3 Effects of defects and deterioration The effects of defects and deterioration on the factored resistance of a member shall be considered. These effects include changes in member strength, stability, and stiffness. The design net area of a deteriorated section shall include sound material only. The distribution of the section loss around the critical section shall also be considered. When it is possible that the member has also lost ductility or post-failure capacity, appropriate adjustments to the reliability index, β , shall be made. Redistribution of load effects between members due to defects and deterioration shall be considered. Any increases in member defects and deterioration expected before the next bridge evaluation shall be accounted for. If a prestressing tendon is significantly corroded, the contribution of the entire tendon to the strength of a component shall be neglected.

Table 14.15 Resistance adjustment factor, U (See Clause 14.14.2.)

November 2006

Resistance category

Resistance adjustment factor, U

Structural Steel (φ per Clause 10.5.7) Plastic moment Yield moment Inelastic lateral torsional buckling moment Elastic lateral torsional buckling moment Compression or tension on gross section Tension on net section Shear (stocky web) Shear (tension field) Bolts Welds Rivets

1.00 1.06 1.04 0.96 1.01 1.18 1.02 1.03 1.20 1.32 1.81

Composite — Slab on steel girder (φ per Clauses 8.4.6 and 10.5.7) Bending moment Shear connectors

0.96 0.94

Reinforced concrete (φ per Clause 8.4.6) Bending moment ρ ≤ 0.4ρb 0.4ρb < ρ ≤ 0.7ρb Axial compression Shear (> min. stirrups)

1.02 0.95 1.06 1.05

Prestressed concrete (φ per Clause 8.4.6) Bending moment ω p ≤ 0.15 0.15 < ω p ≤ 0.30

1.01 0.94

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14.15 Live load capacity factor 14.15.1 General After the loads, load effects, load factors, and factored resistances multiplied by resistance adjustment factors, U, have been calculated, the live load capacity factor, F, shall be calculated as follows: (a) for ultimate limit states, in accordance with Clause 14.15.2.1 or 14.15.2.2, as applicable, or in accordance with the alternative method specified in Clause 14.15.2.3; (b) for serviceability limit states, in accordance with Clause 14.15.3; and (c) for combined load effects, in accordance with Clause 14.15.4.

14.15.2 Ultimate limit states 14.15.2.1 General For ultimate limit states, the value of the live load capacity factor, F, may be calculated as follows for all structural components, except, as specified in Clause 14.15.2.2, for concrete deck slabs and masonry arches:

F=

URr − Sa DD − Sa A A a L L ( 1+ I )

For normal traffic, F shall be calculated for CL1-W or CL1-625-ONT loading and, if F is found to be less than 1.0 and posting of the bridge is an option, F shall also be calculated for CL2-W and CL3-W loading or CL2-625-ONT and CL3-625-ONT loading, as applicable, unless otherwise directed by the Regulatory Authority. For permit traffic, F shall be calculated for the type of vehicle(s) for which a permit is sought.

14.15.2.2 Special cases for ultimate limit states 14.15.2.2.1 Concrete deck slabs For wheel loads, the live load capacity factor, F, shall be calculated as Rr /Lwf , where Rr is as specified in Clause 14.14.1.3.3.

14.15.2.2.2 Masonry arches For each lane of an arch, the live load capacity factor, F, shall be calculated as Pr /La , where Pr is as specified in Clause 14.14.1.5.

14.15.2.3 Mean load method for ultimate limit states (alternative method) As an alternative to Clause 14.15.2.1, the live load capacity factor, F, at the ultimate limit state may be calculated as follows:

(

R exp ⎡ − b VR2 + VS2 ⎢⎣ F= L

)

0.5 ⎤

⎥⎦

− SD

where

R = dRR

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VS

=

(S

2 D

+ SL2

Canadian Highway Bridge Design Code

)

0.5

( ΣD + L )

where

(

)

2 SD = ⎡⎢ ∑ ⎡ VD2 + VAD (d Dd AD D )2 ⎤⎦ ⎤⎦⎥ ⎣ ⎣

0.5

2 2 2 SL = ⎡VAL + VL2 + (VI d I I ) / (1+ d I I ) ⎤ ⎣ ⎦

ΣD = L

0.5

⎡⎣d Ld ALL (1+ d I I ) ⎤⎦

Σd Dd AD D

= d Ld AL L (1+ d I I )

β shall be determined from Clause 14.12.1; D shall be calculated for dead loads in accordance with Clause 14.8.2.1; I (the dynamic load allowance) shall be calculated in accordance with Clause 14.9.3; and L shall be calculated for live loads as specified in Clause 14.9. The bias coefficients and coefficients of variation to be used for calculating F may be taken from Clause C14.15.2.3 of CSA S6.1, from reported values in technical publications, or from field measurements.

14.15.3 Serviceability limit states For serviceability limit states, the live load capacity factor, F, for the applicable loading shall be calculated using the following equation for all structural components:

F =

s SLS − s D − s A a L s L (1 + I )

where α L is as specified in Clause 3.5.1.

14.15.4 Combined load effects Where combined effects such as axial force and moment occur simultaneously in the same element such that the capacity for one is affected by the magnitude of the other, F shall be calculated by successive iteration or another suitable method.

14.16 Load testing 14.16.1 General Bridges may be considered for load testing if the Engineer determines that the analytical evaluation does not accurately assess the actual behaviour of the bridge or there is otherwise a need to establish the actual behaviour of the bridge or its components. When a load test is proposed as part of the evaluation procedure, such a test, including details of loads, loading pattern, instrumentation, condition survey, and analysis, shall be Approved. Load testing shall not be carried out until a theoretical evaluation has been performed in accordance with this Section. This requirement may be waived only if no Plans of the bridge are available or could be made available, in which case testing shall be conducted with extreme care, taking into consideration the possibility of failure of the bridge during testing.

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14.16.2 Instrumentation Components of the bridge shall be instrumented and monitored during the test to the extent considered necessary for safety and detection of any damage or failure, or for verifying certain behaviour considered, or to be considered, in the analysis.

14.16.3 Test load 14.16.3.1 General Testing shall be either static or dynamic, depending on the information required from the tests.

14.16.3.2 Static load test Static test loads shall be applied in a manner that simulates the critical load effects due to the evaluation loads. The load shall be increased in gradual steps within the safe capacity of the loading equipment to at least a predetermined level, provided that no permanent movement of or damage to the bridge components results.

14.16.3.3 Dynamic load test Dynamic testing to establish dynamic characteristics and behaviour of the bridge structure shall be conducted by (a) running test vehicles with known axle loads across the bridge, with no other traffic on the bridge; (b) carrying out the testing under normal traffic conditions, provided that the relevant response can be clearly recorded one vehicle at a time if the response to a single vehicle is required; or (c) using Approved methods.

14.16.4 Application of load test results 14.16.4.1 Evaluation using observed behaviour The bridge structure shall be evaluated taking the observed behaviour into account only if the evaluator is confident that this behaviour will be maintained at the limit state for which the evaluation is being performed. If a dynamic test is performed on the structure to measure actual dynamic amplifications of the vehicle loads or load effects, the dynamic load allowance determined from the test may be used in the evaluation.

14.16.4.2 Live load capacity factors When a live load capacity factor, F, is determined on the basis of load testing, it shall be calculated by dividing Lt by the load effects due to factored live loads. The test results may be extrapolated to determine the live-load-carrying capacity if (a) the maximum applied test load is limited by the capacity of the test equipment; and (b) the stability of the bridge structure or its components is not of concern with any further increase in load. Such an extrapolation, including methods of analysis, projected maximum load capacity, and determination of the live load capacity factors, shall be Approved.

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14.17 Bridge posting 

14.17.1 General The calculations for the live load capacity factors for establishing posting limits shall be carried out in accordance with Clause 14.15 or 14.16. In certain cases, a single posting load, based on engineering judgment and experience, may be used, subject to Approval. Posting methods other than those specified in Clause 14.17, may be used, subject to Approval. Subject to Approval, a concrete bridge with multiple load paths need not be posted if it has been carrying normal traffic without signs of excessive material cracking, deformation, or degradation. Such a bridge shall be inspected at intervals recommended by the evaluator.

14.17.2 Calculation of posting loads When Evaluation Levels 1, 2, and 3 are used as a basis for posting, the smallest value of F from Clause 14.15 or 14.16 shall be calculated and applied as follows: (a) when F  1.0 for Evaluation Level 1, posting shall not be required; (b) when 1.0 > F  0.3 for Evaluation Level 1, triple posting shall be required, with the posting loads for each evaluation level being obtained from Figure 14.8 for the appropriate value of F for each evaluation level; (c) when F < 0.3 for Evaluation Level 1 and F  0.3 for Evaluation Level 3, single posting corresponding to Evaluation Level 3 shall be required, with the posting load being obtained from Figure 14.8 for Evaluation Level 3 only; and (d) when F < 0.3 for Evaluation Level 3, consideration shall be given to closing the bridge.

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1.0

0.04

0.072

0.10

0.9

Le ve l1

el 2

Ev a

lua

Eva lua

tio n

tio n

Lev

Leve ation

0.7

Evalu

Live load capacity factor, F

l3

0.8

0.6

0.5

0.4 0.011

0.02

0.028

0.3 0.02

0

0.04

0.06

0.08

0.10

Posting factor, P

Figure 14.8 Posting loads for gross vehicle weight (See Clauses 14.17.2 and 14.17.3.1.)

14.17.3 Posting signs 14.17.3.1 General The posted weight limit(s) in tonnes shall be PW, where P is the posting factor shown in Figure 14.8 and W is in kilonewtons and as specified in Clause 14.9.1.2. For ONT loads specified for use in Ontario, W equals 625 kN.

14.17.3.2 Single posting signs for vehicles Posting signs shall be in accordance with the regulations set by the Regulatory Authority. Posting shall show the gross vehicle weight to the nearest tonne.

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14.17.3.3 Triple posting signs for vehicles Posting signs shall be in accordance with the regulations set by the Regulatory Authority and shall show the following three types, from top to bottom, respectively, with the maximum gross vehicle weight to the nearest tonne permitted on the bridge for each type: (a) single-unit vehicle corresponding to the Evaluation Level 3 loads; (b) two-unit vehicle corresponding to the Evaluation Level 2 loads; and (c) vehicle train corresponding to the Evaluation Level 1 loads.

14.17.3.4 Posting sign for axle weights The posting sign shall be in accordance with the regulations set by the Regulatory Authority and may show one or more of the following axle types, with the weight limit to the nearest tonne permitted on the bridge for each axle type: (a) single: weight limit = 9.1F; (b) tandem: weight limit = 17.0F; and (c) tridem: weight limit = 23.0F. In all cases, F shall be the live load capacity factor calculated for Evaluation Level 1.

14.18 Fatigue Where there are fatigue-prone details or physical evidence of fatigue-related defects, the bridge and affected components shall be assessed for fatigue and remaining fatigue life at the fatigue limit state, using appropriate methods. As an alternative to assessment, the fatigue-prone details or fatigue-related defects may be monitored by regular inspections. Load combinations and load factors for assessment shall be in accordance with Section 3. Where there are no fatigue-prone details or fatigue-related defects, the evaluation need not consider the fatigue limit state if neither the use nor the behaviour of the bridge is changed.

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Annex A14.1 (normative) Equivalent material strengths from tests of samples Note: This Annex is a mandatory part of this Code.

A14.1.1 Structural steel Coupon specimens for determination of the yield and ultimate tensile strengths of structural steel shall be tested in accordance with CSA G40.20. At least three coupons shall be obtained from the components being evaluated. The “equivalent” yield strength of each coupon shall be its reported yield strength. If a coupon is obtained from the flange of a rolled member, its equivalent yield strength may be taken as 1.05 times the reported yield strength. The yield strength, fy , used for evaluation shall be calculated as follows:

(

)

fy = fy − 28 exp ( −1.3ksV ) where and V are, respectively, the average value and coefficient of variation of the yield strengths, and ks fy is obtained from Table A14.1.1, in which n is the number of strength tests.

Table A14.1.1 Coefficient of variation modification factor, ks (See Clauses A14.1.1 and A14.1.3.) n

ks

3 4 5 6 8 10 12 16 20 25 30 or more

3.46 2.34 1.92 1.69 1.45 1.32 1.24 1.14 1.08 1.03 1.00

A14.1.2 Concrete The compressive strength of sound concrete shall be determined from the strengths of cores obtained from the components being evaluated. The core tests shall be conducted in accordance with CAN/CSA-A23.2. The strength of cores smaller than 100 mm diameter shall be adjusted to approximate the equivalent strengths of 100 mm diameter cores. The appropriate strength-correction factor shall be determined from cores of both diameters obtained from the components being evaluated. It may be assumed that the strengths of 100 and 150 mm diameter cores are equivalent. The equivalent strength of 100 mm diameter cores shall be increased by 8% for cores soaked 40 h in water or reduced by 5% for cores dried 7 d in air before testing.

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The equivalent specified compressive strength, fc’, used for evaluation shall be calculated as follows: 0.5 ⎤ ⎡ 2 fc′ = 0.9fc ⎢1− 1.28 ⎡( kcV ) / n + 0.0015⎤ ⎥ ⎣ ⎦ ⎦ ⎣

where fc is the average core strength, modified to account for the diameter and moisture condition of the core, V is the coefficient of variation of the core strengths, n is the number of cores tested, and kc is obtained from Table A14.1.2.

Table A14.1.2 Coefficient of variation modification factor, kc (See Clause A14.1.2.) n 2 3 4 5 6 8 10 12 16 20 25 or more

kc 2.40 1.47 1.28 1.20 1.15 1.10 1.08 1.06 1.05 1.03 1.02

A14.1.3 Reinforcing steel Coupon specimens for determining the yield and ultimate tensile strengths of reinforcing steel shall be tested in accordance with CAN/CSA-G30.18. At least three coupons, taken from different bars, shall be obtained from the components being evaluated. The yield strength, fy , used for evaluation shall be calculated as follows:

(

)

fy = fy − 24 exp ( −1.3ksV ) where and V are, respectively, the average value and coefficient of variation of the yield strengths, and ks fy is obtained from Table A14.1.1, in which n is the number of strength tests.

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Annex A14.2 (normative) Evaluation Level 1 (vehicle trains) in Ontario Note: This Annex is a mandatory part of this Code.

A14.2.1 General For Evaluation Level 1 in Ontario, the CL1-625-ONT Truck Load or the CL1-625-ONT Lane Load shown in Figure A14.2.1 shall be used instead of the CL1-W Truck Load and CL1-W Lane Load, respectively. Axle No. Axle load, kN Wheel load, kN

5 120 60

4 175 87.5

3 2 140 140 70 70

1 50 25

Gross load = 625 kN 3.6 m

1.2 m

6.6 m

6.6 m

18 m

1.8 m

0.6 m (typ.)

CL Wheel

Travel

0.25 m (typ.)

0.25 m (typ.)

0.25 m (typ.)

3.0 m truck width

CL Axle (typical)

CL Wheel

CL1-625-ONT Truck Load (Elevation)

0.6 m (typ.)

CL1-625-ONT Truck Load (Plan) Axle load, kN

40

112 112

140

96 q

3.6 m

1.2 m

6.6 m

6.6 m

18 m

CL1-625-ONT Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure A14.2.1 Evaluation Level 1 loads with CL1-625-ONT Truck (See Clauses 14.9.1.7 and A14.2.1.)

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Annex A14.3 (normative) Evaluation Level 2 (two-unit vehicles) in Ontario Note: This Annex is a mandatory part of this Code.

A14.3.1 General For Evaluation Level 2 in Ontario, the CL2-625-ONT Truck Load or the CL2-625-ONT Lane Load shown in Figure A14.3.1 shall be used instead of the CL2-W Truck Load and CL2-W Lane Load, respectively. Axle No. Axle load, kN Wheel load, kN

4 175 87.5

3 2 140 140 70 70

1 50 25

Gross load = 505 kN 3.6 m

1.2 m

6.6 m

11.4 m

CL Axle (typical)

0.25 m (typ.)

1.8 m

0.6 m (typ.)

CL Wheel

Travel

0.25 m (typ.)

0.25 m (typ.)

3.0 m truck width

CL Wheel

CL2-625-ONT Truck Load (Elevation)

0.6 m (typ.)

CL2-625-ONT Truck Load (Plan) Axle load, kN

40

112

112

140 q

3.6 m

1.2 m

6.6 m

11.4 m

CL2-625-ONT Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure A14.3.1 Evaluation Level 2 loads with CL2-625-ONT Truck (See Clauses 14.9.1.7 and A14.3.1.) November 2006

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Annex A14.4 (normative) Evaluation Level 3 (single-unit vehicles) in Ontario Note: This Annex is a mandatory part of this Code.

A14.4.1 General For Evaluation Level 3 in Ontario, the CL3-625-ONT Truck Load or the CL3-625-ONT Lane Load shown in Figure A14.4.1 shall be used instead of the CL3-W Truck Load and CL3-W Lane Load, respectively. Axle No. Axle load, kN Wheel load, kN

3 2 140 140 70 70

1 50 25

Gross load = 330 kN 3.6 m

1.2 m

4.8 m

CL Axle (typical)

0.25 m (typ.)

0.25 m (typ.)

1.8 m

0.6 m (typ.)

3.0 m truck width

Travel

0.25 m (typ.)

CL Wheel

CL Wheel

CL3-625-ONT Truck Load (Elevation)

0.6 m (typ.)

CL3-625-ONT Truck Load (Plan)

Figure A14.4.1 Evaluation Level 3 loads with CL3-625-ONT Truck (See Clauses 14.9.1.7 and A14.4.1.) (Continued)

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Axle load, kN

40

112

112 q

3.6 m

1.2 m

4.8 m

CL3-625-ONT Lane Load Note: The values of the uniformly distributed load, q, for each highway class (see Section 1) are as follows: (a) Class A: 9 kN/m; (b) Class B: 8 kN/m; and (c) Class C or D: 7 kN/m.

Figure A14.4.1 (Concluded)

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Section 15 — Rehabilitation and repair 15.1 15.2 15.3 15.3.1 15.3.2 15.3.3 15.3.4 15.3.5 15.3.6 15.3.7 15.3.8 15.4 15.5 15.6 15.6.1 15.6.2 15.7 15.8 15.8.1 15.8.2

Scope 688 Symbols 688 General requirements 688 Limit states 688 Condition data 688 Rehabilitation loads and load factors 688 Analysis 688 Factored resistances 688 Fatigue 688 Bridge posting 689 Seismic upgrading 689 Special considerations 689 Data collection 689 Rehabilitation loads and load factors 689 Loads 689 Load factors and load combinations 691 Analysis 692 Resistance 692 Existing members 692 New members 692

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Section 15 Rehabilitation and repair 15.1 Scope This Section specifies minimum requirements for the rehabilitation of bridges. The requirements specified in this Section relate only to loads, load factors, resistances, and other design criteria relevant to the rehabilitation of bridges. Material specifications and rehabilitation and maintenance procedures are not covered in this Section but should conform to accepted Canadian good practice.

15.2 Symbols See Clause 14.3 for the symbols used in this Section.

15.3 General requirements Note: See Clause 15.4 for special considerations.

15.3.1 Limit states Unless otherwise specified by the Owner or required by this Section, all rehabilitated members shall satisfy the ultimate limit state and serviceability limit state requirements specified as part of the design requirements of Sections 1 to 13 and 16, except that if the purpose of the rehabilitation is to allow passage of a controlled vehicle, the only load combination that shall be considered is permanent loads plus the control vehicle, with the load factors specified in Section 14.

15.3.2 Condition data Condition data on dimensions, member sizes, geometry, material strengths, extent and location of deterioration, distress, and permanent distortion shall be collected, to the extent that they will affect the rehabilitation design and preparation of Plans, in accordance with Clause 15.5.

15.3.3 Rehabilitation loads and load factors The rehabilitation loads and load factors for which the bridge or its components are to be rehabilitated shall be selected in accordance with Clause 15.6.

15.3.4 Analysis The structure shall be analyzed for the selected loads and limit states in accordance with Clause 15.7.

15.3.5 Factored resistances The factored resistances for each element being considered shall be calculated in accordance with Clause 15.8.

15.3.6 Fatigue The resistance of existing members and materials to fatigue loadings and imposed deformations shall not be impaired by the rehabilitation.

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15.3.7 Bridge posting If, after rehabilitation, the bridge needs to be posted for load restriction, posting loads shall be calculated in accordance with Clause 14.17.

15.3.8 Seismic upgrading Seismic upgrading of the bridge shall be carried out in accordance with Section 4.

15.4 Special considerations During the planning and design stages of bridge rehabilitation, special consideration shall be given to, but not limited to, the following: (a) access; (b) the aesthetics of the rehabilitation; (c) architectural features; (d) constructibility; (e) the difference between as-built and as-designed information, including modifications made after initial construction; (f) drainage; (g) economics, including life cycle costs or phased rehabilitation to suit available cash flow; (h) environmental impacts, including stream improvements; (i) the extent of defects and deterioration; (j) the geometry of approach and of the highway beyond the ends of the structure; (k) heritage aspects; (l) liaison with other agencies and individuals, including utility companies, railways, conservation authorities, municipalities, and private property owners; (m) local expertise; (n) the presence of utilities; (o) provision for further rehabilitation at a later date; (p) the remaining service life before and after rehabilitation; (q) structural safety during all construction stages of rehabilitation; (r) traffic conditions; (s) waterproofing; and (t) vibration.

15.5 Data collection In addition to the condition survey and determination of material strengths required by Clauses 14.6 and 14.7, inspection and testing shall be carried out as necessary to ascertain that the planned rehabilitation is compatible with the geometry, material characteristics, and state of stress of the structure.

15.6 Rehabilitation loads and load factors 15.6.1 Loads 15.6.1.1 General Loads, load factors, and their application shall be in accordance with Section 3, except as modified by Clauses 15.6.1.2 to 15.6.1.12.

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15.6.1.2 Permanent loads Permanent loads shall be based on the dimensions and information on available drawings and verified in the field. When drawings are not available, field measurements shall be used. Addition, removal, or redistribution of permanent loads resulting from the rehabilitation shall be included in the rehabilitation design.

15.6.1.3 Rehabilitation design live loads 15.6.1.3.1 General The rehabilitation design live loads specified in this Section do not include an allowance for future traffic growth beyond what is specified in Clause 15.6.1.3.2 for the appropriate value of W in Clause 14.9.1.

15.6.1.3.2 Normal traffic Evaluation Level 1 Live Load CL1-W specified in Clause 14.9.1 shall be used for the rehabilitation design of bridges that are to carry unrestricted normal traffic after rehabilitation. For restricted normal traffic, a suitable fraction of CL1-W, CL2-W, or CL3-W shall be used in accordance with Table 15.1 if rehabilitation to CL1-W is not economically justifiable. For Ontario, ”625-ONT” shall be substituted for “-W” in this Clause.

Table 15.1 Rehabilitation design live loads for restricted normal traffic (See Clause 15.6.1.3.2.) Rehabilitation level

Proposed use

CL2

All trucks (excluding truck trains)

CL3

Urban buses, milk trucks, and single-unit trucks

75% of CL3

Light trucks, emergency vehicles of gross vehicle weight less than that of CL1-W, and school buses

50% of CL3

Passenger vehicles, light emergency vehicles, and maintenance vehicles

Pedestrian

Pedestrians only

Note: Bridges rehabilitated for restricted normal traffic shall be posted in accordance with Clause 14.17.

15.6.1.3.3 Vehicles operating under permit For bridges to be rehabilitated for the passage of a vehicle operating under permit, the wheel loads, axle spacing, and other appropriate dimensions available from actual measurements or from available drawings of the loaded vehicle shall be used. The position and direction of the vehicle and the simultaneous application of other live loads shall be in accordance with controls imposed by the Owner of the bridge.

15.6.1.3.4 Design lanes The number of design lanes and the modification factors for multiple lane loading shall be as specified in Clause 14.9.4.

15.6.1.4 Dynamic load allowance 15.6.1.4.1 Unrestricted highway live loads For bridges to be rehabilitated for unrestricted highway live loads, the dynamic load allowance shall be as specified in Section 3.

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15.6.1.4.2 Restricted highway live loads For bridges to be rehabilitated and posted for restricted highway live loads, the dynamic load allowance specified in Section 3 shall be multiplied by the dynamic load allowance modification factor specified in Clause 14.9.3.

15.6.1.5 Thermal, shrinkage, and creep effects Provision shall be made in the rehabilitation design for expansion and contraction due to temperature, shrinkage, and creep. Load effects induced by any restraints on these movements shall be included in the rehabilitation design.

15.6.1.6 Wind loads Wind loads shall be as specified in Section 3.

15.6.1.7 Collision loads Collision loads in accordance with Section 3 shall be considered unless effective measures are taken to protect the bridge and its components against these loads.

15.6.1.8 Settlement and permanent deformations Load effects resulting from settlement and permanent deformations in the bridge or its components shall be included in the rehabilitation design.

15.6.1.9 Seismic loads Seismic loads shall be considered in accordance with Section 4.

15.6.1.10 Stream flow and ice pressure loads Load effects resulting from stream flow and ice pressure shall be considered in accordance with Section 3.

15.6.1.11 Component deterioration Load effects resulting from redistribution of loads due to deterioration of components shall be included in the rehabilitation design.

15.6.1.12 Loads induced by the rehabilitation Loads induced in the bridge or its components during rehabilitation construction and any changes in the bridge or its components resulting from the rehabilitation shall be included in the rehabilitation design.

15.6.2 Load factors and load combinations 15.6.2.1 General Unless otherwise specified by the Regulatory Authority, all load factors and load combinations shall be in accordance with Section 3.

15.6.2.2 Minimum rehabilitation load factors If the purpose of the rehabilitation is to allow passage of a permit vehicle (see Clause 14.9.2), the load factors shall be in accordance with Section 14. The reliability index,  , for all rehabilitated members shall be selected using Inspection Level INSP1. If specified by the Regulatory Authority, load factors from Section 14 may be used for a bridge rehabilitation intended to carry normal traffic, but shall be selected using Inspection Level INSP1.

15.6.2.3 Total factored load effect For each load combination, every load that is to be included shall be multiplied by the specified load factor and then added to the other loads to obtain the total factored load effect.

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15.6.2.4 Overall minimum load factor Except for PB or PC vehicles, the total factored load effect for ULS Combination 1 (see Table 3.1) shall not be less than 1.25 times the sum of the unfactored load effects. This requirement may be waived if the member provides a live load capacity factor, F, greater than or equal to 1.0 in accordance with the mean load method specified in Clause 14.15.2.3. For PC vehicles, the total factored load effect for ULS Combination 1 shall not be less than 1.15 times the sum of the unfactored load effects.

15.7 Analysis Structural analysis shall be performed in accordance with this Section and the other applicable Sections of this Code. The effects of member connections, connection continuity, support restraints, the contribution of the secondary components, and the interaction between the new and existing components of the bridge shall be considered in the analysis. Structural analysis shall consider the extent of member deterioration and existing locked-in stresses due to system behaviour, their effect on the strength and stiffness characteristics of the member, and their effect on the strength of the structural system.

15.8 Resistance 15.8.1 Existing members 15.8.1.1 General The factored resistances of existing members, including existing members strengthened with new material, shall be determined in accordance with Clauses 14.14.1 and 14.14.2. The factored resistances of existing members shall be reduced to account for any member defects or deterioration in accordance with Clause 14.14.3. In addition, the effects on member resistance and ductility of different stress levels in the new and existing portions of hybrid members shall be considered.

15.8.1.2 Strengthening using fibre-reinforced polymer In addition to satisfying the requirements of Clause 15.8.1.1, members strengthened using fibre-reinforced polymer shall satisfy the durability requirements of Clause 16.4. The design of concrete or wood members strengthened with fibre-reinforced polymer shall also satisfy the requirements of Clause 16.11 or 16.12, respectively.

15.8.2 New members The factored resistances of new members shall be determined in accordance with Sections 5 to 13 and 16.

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Canadian Highway Bridge Design Code

Section 16 — Fibre-reinforced structures 16.1 16.1.1 16.1.2 16.1.3 16.1.4 16.2 16.3 16.3.1 16.3.2 16.4 16.4.1 16.4.2 16.4.3 16.4.4 16.4.5 16.4.6 16.4.7 16.4.8 16.5 16.5.1 16.5.2 16.5.3 16.6 16.6.1 16.6.2 16.6.3 16.7 16.7.1 16.7.2 16.7.3 16.7.4 16.8 16.8.1 16.8.2 16.8.3 16.8.4 16.8.5 16.8.6 16.8.7 16.8.8 16.9 16.9.1 16.9.2 16.9.3 16.9.4 16.9.5 16.9.6 16.10 16.11 16.11.1 16.11.2

Scope 695 Components 695 Fibres 695 Matrices 695 Uses requiring Approval 695 Definitions 695 Abbreviations and symbols 697 Abbreviations 697 Symbols 698 Durability 701 FRP tendons, primary reinforcement, and strengthening systems 701 FRP secondary reinforcement 701 Fibres in FRC 701 Cover to reinforcement 702 Protective measures 702 Allowance for wear in deck slabs 702 Detailing of concrete components for durability 702 Handling, storage, and installation of fibre tendons and primary reinforcement 702 Fibre-reinforced polymers 702 Material properties 702 Confirmation of the specified tensile strength 702 Resistance factor 703 Fibre-reinforced concrete 703 General 703 Fibre volume fraction 703 Fibre dispersion in concrete 704 Externally restrained deck slabs 704 General 704 Full-depth cast-in-place deck slabs 705 Cast-in-place deck slabs on stay-in-place formwork 706 Full-depth precast concrete deck slabs 706 Concrete beams and slabs 711 General 711 Deformability and minimum reinforcement 711 Non-prestressed reinforcement 712 Development length for FRP bars and tendons 712 Development length for FRP grids 712 Tendons 712 Design for shear 713 Internally restrained cast-in-place deck slabs 714 Stressed wood decks 715 General 715 Post-tensioning materials 715 Post-tensioning system 715 Stressing procedure 716 Design of bulkheads 716 Stressed log bridges 716 Barrier walls 718 Rehabilitation of existing concrete structures with FRP 719 General 719 Flexural and axial load rehabilitation 720

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16.11.3 16.12 16.12.1 16.12.2 16.12.3

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Shear rehabilitation with externally bonded FRP systems 722 Rehabilitation of timber bridges 724 General 724 Strengthening for flexure 725 Strengthening for shear 726

Annexes A16.1 (normative) — Installation of FRP strengthening systems 729 A16.2 (normative) — Quality control for FRP strengthening systems 732

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Canadian Highway Bridge Design Code

Section 16 Fibre-reinforced structures 16.1 Scope 16.1.1 Components The requirements of this Section apply to the following components containing fibre reinforcement: (a) fully or partially prestressed concrete beams and slabs; (b) non-prestressed concrete beams, slabs, and deck slabs; (c) externally and internally restrained deck slabs; (d) stressed wood decks; (e) barrier walls; (f) existing concrete elements with externally bonded fibre-reinforced polymer systems and near-surface-mounted reinforcement; and (g) existing timber elements with externally or internally bonded glass-fibre-reinforced polymer systems and near-surface-mounted reinforcement.

16.1.2 Fibres This Section covers fibre reinforcement in which the fibre comprises one or more of the following: (a) glass; (b) carbon; (c) aramid; (d) a low modulus polymer or polymers; and (e) steel.

16.1.3 Matrices This Section covers fibre-reinforced composites in which the matrix comprises one or more of the following: (a) epoxy resin; (b) saturated polyester resin; (c) unsaturated polyester resin; (d) vinylester resin; (e) polyurethane; and (f) Portland-cement-based mortar or concrete.

16.1.4 Uses requiring Approval Uses of fibre-reinforced polymers in structures or strengthening schemes that do not meet the requirements of this Section require Approval.

16.2 Definitions The following definitions apply in this Section: Adhesive — a polymeric substance applied to mating surfaces to bond them together. Bar — a non-prestressed FRP element with a nominally rectangular or circular cross-section that is used to reinforce a structural component.

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Bond-critical applications — applications of FRP systems that rely on bond to the substrate for load transfer. Contact-critical applications — applications of FRP systems that rely on continuous intimate contact between the substrate and the FRP system. Continuous fibres — aligned fibres whose individual lengths are significantly greater than 15 times the critical fibre length. Critical fibre length — the minimum length required to develop the full tensile strength of a fibre in a matrix. Cure — the process of causing an irreversible change in the properties of a thermosetting resin by chemical reaction. Deck slab — a concrete slab supported by girders, stringers, or floor beams. Duct — a conduit for post-tensioning tendons. Equivalent diameter — the diameter of a circular cross-section having the same cross-sectional area as that of the non-circular section. Externally restrained deck slab — a deck slab with external straps or other confining systems designed in accordance with Clause 16.7. Fibre-reinforced composite — an assembly of chemically dissimilar materials, being the matrix and fibres, whose properties in combination are more widely useful than those of the constituent materials. Fibre-reinforced concrete (FRC) — a fibre-reinforced composite in which the matrix is Portland cement concrete or mortar and the fibres are discontinuous and uniformly and randomly distributed. Fibre-reinforced polymer (FRP) — a fibre-reinforced composite with a polymeric matrix and continuous fibre reinforcement of aramid, carbon, or glass. Fibres — small-diameter filaments of materials of relatively high strength, i.e., glass, carbon, aramid, low modulus polymer, or steel. Fibre volume fraction — the ratio of the volume of the fibres to the volume of the fibre-reinforced composite. Gel time — the time a material takes to become pseudo-plastic. Glass transition temperature — the midpoint of the temperature range over which an amorphous material changes from a brittle and vitreous state to a plastic state or vice versa. Grid — a prefabricated planar assembly consisting of bars in an orthogonal arrangement. Impregnate — to saturate fibre assemblies with a resin. Internally restrained deck slab — a deck slab containing embedded bottom transverse reinforcement designed in accordance with Clause 16.8.8. Low modulus polymers — polymers with a modulus of elasticity less than 10 GPa, e.g., nylon, polyolefin, polypropylene, and vinylon. Matrix — the material in a fibre-reinforced composite component that contains aligned or randomly distributed fibres. Near-surface-mounted reinforcement (NSMR) — an FRP bar or strip bonded inside a groove near a surface of a structural component.

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Open time — the maximum time for joining together adherents after adhesive has been applied in order to avoid surface alteration of the adhesive. Plate — an FRP component whose thickness is significantly less than its other dimensions. Pot life — the time one can work with primer, putty, and/or adhesive after mixing resin and a hardener before the primer, putty, and/or adhesive starts to harden in the mixture vessel. Primary reinforcement — reinforcement provided mainly for strength. Rope — an assembly of bundled continuous fibres. Secondary reinforcement — reinforcement provided mainly for control of cracking. Sheath — a protective encasement for a tendon or rope. Sheet — a flexible component comprising fibres. Shelf life — the length of time a material can be stored under specified environmental conditions and still continue to meet all applicable specifications for use. Slab — a concrete slab that transfers load directly to the substructure. Strand — a linear component that constitutes all or part of a tendon. Strap — a linear component of steel or FRP that provides transverse restraint externally in a deck slab. Stressed log bridge — a bridge deck made with logs that are trimmed to obtain two parallel faces and that are post-tensioned transversely. Stressed wood deck — a stress-laminated wood deck or stressed log bridge. Stress-laminated wood deck — a laminated wood deck that is post-tensioned perpendicular to the deck laminates. Supporting beam — a stringer, floor beam, or girder. Tendon — an FRP or high-strength steel element that imparts prestress to a structural component. Thermoplastic matrix — a polymer capable of being repeatedly softened by an increase in temperature and hardened by a decrease in temperature. Thermoset matrix — a polymer that changes into a substantially infusible and insoluble material when cured by heat, chemicals, or both. Wet lay-up — a method of making an FRP-laminated product that involves applying a resin system as a liquid when the fabric is put in place.

16.3 Abbreviations and symbols 16.3.1 Abbreviations The following abbreviations apply in this Section: AFRP — aramid-fibre-reinforced polymer CFRP — carbon-fibre-reinforced polymer FLS

— fatigue limit state

FRC

— fibre-reinforced concrete

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FRP

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— fibre-reinforced polymer

GFRP — glass-fibre-reinforced polymer NSMR — near-surface-mounted reinforcement



SLS

— serviceability limit state

ULS

— ultimate limit state

16.3.2 Symbols The following symbols apply in this Section: A

= area of cross-section of a strap or bar, mm2

AFRP

= area of cross-section of an FRP bar, plate, sheet, or tendon, mm2

Af

= area of cross-section of deck slab formwork along a section parallel to the beams, per unit length of the formwork, mm2/mm

Ap

= area of steel tendons in the tension zone, mm2

As

= area of cross-section of steel or FRP reinforcing bars used in edge stiffening of deck slabs, as shown in Figures 16.2 and 16.5, mm2

Av

= area of transverse shear reinforcement perpendicular to the axis of a member, mm2

Av,min

= minimum required area of transverse shear reinforcement perpendicular to the axis of a member, mm2

b

= smallest log diameter, mm; height of the flat face of a trimmed log, as shown in Figure16.10, mm; width of a rectangular section, mm

bv

= effective width of web within depth dlong , mm (see Clause 8.9.1.6)

bw

= width of web of a T-section, mm

Dg

= diameter of a circular column or equivalent diameter of a rectangular column, mm (see Clause 16.11.2.5.6)

d

= effective depth of a reinforced concrete component, being the distance from the compression face to the centroid of the tensile reinforcement, mm

dFRP

= effective shear depth for FRP, mm, calculated in the same manner as dlong for longitudinal reinforcement

db

= equivalent diameter of a bar, tendon, or strand in a multiple-strand tendon, mm

dc

= distance from the centroid of the tension reinforcement to the extreme tension surface of concrete, mm

dcs

= smaller of the distance from the closest concrete surface to the centre of the bar being developed, or two-thirds the centre-to-centre spacing of the bars being developed, mm

dlong

= effective shear depth for longitudinal reinforcement, mm

ds

= diameter of an FRP stirrup in Clause 16.8.7(c), mm; distance from the top of the slab to the centroid of the bottom transverse FRP bars in Clause 16.8.8.1(b), mm

E

= modulus of elasticity, MPa

EFRP

= mean modulus of elasticity of FRP bars, plates, sheets, and tendons, MPa

Ep

= modulus of elasticity of steel tendons, MPa

Es

= modulus of elasticity of steel, MPa

EvFRP

= modulus of elasticity of the FRP stirrups, MPa (see Clause 16.8.7)

EI

= flexural rigidity, N•mm2

F

= live load capacity factor (see Clause 14.15.2)

FSLS

= dimensionless factor (see Clause 16.8.3)

Fs

= factor in Clauses 16.7.2(c) and 16.7.3(g), MPa

Ft

= dimensionless factor (see Clause 16.5.2)

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fFRP

= stress in the tension FRP reinforcement, MPa

fFRPbend

= specified tensile strength of the straight portion of an FRP bent stirrup, MPa

fFRPu

= specified tensile strength of an FRP bar, grid, plate, sheet, tendon, or aramid rope, MPa

fbu

= specified bending strength of wood, MPa

fc’

= specified compressive strength of concrete, MPa

fcc’

= compressive strength of confined concrete, MPa

fcr

= cracking strength of concrete, MPa

fFRP

= confinement pressure due to FRP strengthening at the ULS, MPa

fpo

= stress in tendons when the stress in the surrounding concrete is zero, MPa

fps

= maximum permissible stress in a tendon at the ULS, MPa

fvu

= specified shear strength of timber (see Section 9)

fy

= specified yield strength of steel reinforcing bars, MPa

h

= depth of a timber beam, mm

h1

= distance from the centroid of tension reinforcement to the neutral axis, mm

h2

= distance from the extreme flexural tension surface to the neutral axis, mm

J

= overall performance factor for a concrete beam or slab with a rectangular section or a T-section

KbFRP

= non-dimensional factor (see Clauses 16.12.2.1 and 16.12.2.2)

Ktr

= transverse reinforcement index, mm (see Clause 8.15.2.2)

KvFRP

= non-dimensional factor (see Clauses 16.12.3.1 and 16.12.3.2)

kb

= coefficient depending on bond between FRP and concrete

k1

= bar location factor (see Clause 8.15.2.4); concrete strength factor (see Clause 16.11.3.2)

k2

= non-dimensional factor (see Clause 16.11.3.2)

k4

= bar surface factor

Le

= effective anchorage length of an FRP sheet, mm (see Clause 16.11.3.2)

Lu

= unsupported length of a transverse edge beam, mm

a

= minimum required anchorage length for externally bonded FRP beyond the point where no strengthening is required, mm

d

= development length of FRP bars and tendons, mm

Mc

= moment at a section corresponding to a maximum compressive concrete strain of 0.001, N•mm

Mcr

= cracking moment, N•mm

Mf

= factored moment at a section, N•mm

Mr

= factored flexural resistance of a section, N•mm

Mult

= ultimate moment capacity of a section, N•mm

Nf

= factored axial load normal to the cross-section occurring simultaneously with Vf , including the effects of tension due to creep and shrinkage, N

n

= number of test specimens

Po

= factored axial resistance of a section in pure compression, N

Pr

= factored axial resistance of a section in compression with minimum eccentricity, N

Ri

= post-cracking residual strength index

r

= radius of curvature of the bend of an FRP stirrup, mm; radius of curvature of the saddle for a deflected straight tendon, mm

S

= centre-to-centre spacing of beams supporting a deck slab, mm

S

= spacing of straps, mm

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s sFRP Tgw t tFRP tc ts V VFRP Vc Vf Vp

Vr Vs Vst wFRP wcr 





  FRPe  FRPu v x  V s vFRP N v FRP c c ult

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= spacing of shear or tensile reinforcement, mm = spacing of externally bonded FRP bands on concrete for shear strengthening, measured along the axis of the member, mm = wet glass transition temperature, i.e., the glass transition temperature after moisture uptake by the polymer, °C = thickness of an externally restrained deck slab, including that of the stay-in-place formwork, if present, mm = total thickness of externally bonded FRP plates or sheets, mm = thickness of cast-in-place concrete in a deck slab cast on a stay-in-place formwork, if present, mm = projection of a shear connector or other shear-connecting device into a deck slab, as shown in Figure 16.1 for shear connectors, mm = coefficient of variation of the strength of FRP components, being the ratio of the standard deviation to the mean = factored shear resistance provided by the FRP shear reinforcement, N = factored shear resistance provided by tensile forces in concrete, N = factored shear force at a section, N = component in the direction of the applied shear of all of the effective prestressing forces crossing the critical section, factored by p (see Clause 8.4.6), to be taken as positive if resisting the applied shear, N = factored shear resistance, N = factored shear resistance provided by the steel shear reinforcement, N = factored shear resistance provided by the shear reinforcement, N = width of an FRP sheet measured perpendicular to the direction of the main fibres, mm = crack width at the tensile face of the flexural component, mm = angle of inclination of internal or external transverse reinforcement to the longitudinal axis of the member, degrees = factor used to account for shear resistance of cracked concrete = effective strain in FRP (see Clause 16.11.3.2) = ultimate strain in FRP = strain in an FRP stirrup = longitudinal strain calculated in accordance with Clause 16.8.7 = angle of inclination of the principal diagonal compressive stress to the longitudinal axis of the member, degrees = bond reduction factor (see Clause 16.11.3.2) = ratio of the cross-sectional area of the longitudinal FRP reinforcement to the effective cross-sectional area of the beam = ratio of the total cross-sectional area of the legs of an FRP stirrup to the product of the width of the beam and the spacing of the stirrups = stress in concrete due to axial loads, MPa = stress calculated in accordance with Clause 16.8.7 = resistance factor for FRP components (see Clause 16.5.3) = resistance factor for concrete (see Clause 8.4.6) = curvature at a section when the moment is Mc , mm–1 = curvature at a section when the moment is Mult , mm–1

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Canadian Highway Bridge Design Code

16.4 Durability 16.4.1 FRP tendons, primary reinforcement, and strengthening systems For FRP bars and grids (when used as primary reinforcement in concrete), FRP tendons, and FRP systems used in the strengthening of concrete and timber components, the matrices shall comprise only thermosetting polymers, except that thermoplastic polymers with proven durability may also be used with Approval. Matrices and the adhesives of FRP systems with a wet glass transition temperature, Tgw , of less than the sum of 20 °C and the maximum daily mean temperature specified in Section 3 shall not be used. Tendons, fibre ropes, and primary reinforcement in concrete, being FRP bars or grids, shall be used only as permitted in Table 16.1, regardless of environmental conditions. Tendons shall also comply with Clause 16.8.6.2. Subject to the conditions specified in Clauses 16.11 and 16.12, AFRP, CFRP, and GFRP shall be considered permissible reinforcement.

Table 16.1 Conditions of use for FRP tendons and primary reinforcement (See Clause 16.4.1.) Component Application

AFRP*

CFRP

GFRP

Aramid rope*

Permitted

Permitted

Permitted

—

Non-alkaline grout

Permitted

Permitted

Permitted

—

Cement-based grout

Permitted

Permitted

Permitted

—

Internal

Permitted

Permitted

Permitted

Permitted

External

Permitted

Permitted

Permitted

Permitted

Non-prestressed beams and slabs

Permitted

Permitted

Permitted

—

Non-prestressed deck slabs

Permitted

Permitted

Permitted

Permitted

Stressed wood decks

Permitted

Not permitted

Permitted

Permitted

Barrier walls

Permitted

Permitted

Permitted

—

Prestressed concrete beams and slabs Pre-tensioned Post-tensioned Grouted

Ungrouted

*In dry and ultraviolet-protected conditions.

16.4.2 FRP secondary reinforcement For FRP secondary reinforcement in concrete, FRPs with either thermosetting or thermoplastic polymers shall be permitted unless the matrix is susceptible to degradation from alkali.

16.4.3 Fibres in FRC For FRC, the use of carbon, nylon, polypropylene, polyvinyl alcohol, steel, and vinylon fibres shall be permitted. The use of other fibres shall require Approval.

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16.4.4 Cover to reinforcement The minimum clear cover and its construction tolerance shall be 35 ± 10 mm for FRP bars and grids and 50 ± 10 mm for FRP tendons. For pretensioned concrete, the cover and construction tolerance shall not be less than the equivalent diameter of the tendon ±10 mm. For post-tensioned concrete, the cover and construction tolerance shall not be less than one-half the diameter of the duct ±10 mm.

16.4.5 Protective measures Anchors for aramid fibre ropes and FRP tendons in concrete shall be of suitably durable materials. For stressed wood decks, all steel components of the post-tensioning system shall be of stainless steel or suitably protected against corrosion. Exposed tendons and FRP strengthening systems that are deemed susceptible to damage by ultraviolet rays or moisture shall be protected accordingly. Where the externally bonded FRPs are susceptible to impact damage from vehicles, ice, and debris, consideration shall be given to protecting the FRP systems. Direct contact between CFRP and metals shall not be allowed. Aramid ropes shall be protected against moisture ingress by suitably designed sheaths and anchors.

16.4.6 Allowance for wear in deck slabs A deck slab without a wearing course shall have an additional thickness of 10 mm as an allowance for wear.

16.4.7 Detailing of concrete components for durability Clauses 8.11.3.1 and 8.11.3.2 shall apply with respect to detailing of concrete components for durability.

16.4.8 Handling, storage, and installation of fibre tendons and primary reinforcement To avoid damage to fibre tendons and primary reinforcement, instructions for careful handling, storage, and installation of primary reinforcement shall be specified in the Plans. The specifications for FRP strengthening systems shall be in accordance with Annex A16.1.

16.5 Fibre-reinforced polymers 16.5.1 Material properties The specified tensile strength, fFRPu , of an FRP bar, grid, plate, sheet, tendon, or aramid rope used in the design shall be its fifth percentile tensile strength; the specified modulus of elasticity, EFRP , shall be the mean modulus of elasticity. In the absence of test data, properties provided by the manufacturer may be used.

16.5.2 Confirmation of the specified tensile strength The Plans shall specify that the value of fFRPu shall be confirmed by the appropriate test method specified in CAN/CSA-S806. The specified tensile strength shall be deemed to have been confirmed if the average test strength of the specimens multiplied by Ft is at least equal to the specified tensile strength. Ft , which depends on the coefficient of variation of the tensile strength, V, shall be calculated as follows:

Ft =

1− 1.645V 1+ (1.645V ) / n

where n

702

= number of test specimens (which shall not be less than five)

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

16.5.3 Resistance factor

The resistance factor,  FRP , for pultruded FRP and aramid fibre rope shall be as specified in Table 16.2. For non-pultruded FRP made by wet lay-up,  FRP shall be 0.75 times the corresponding value in Table 16.2. For non-pultruded FRP made in accordance with other factory-based controlled processes, FRP shall be 0.85 times the corresponding value in Table 16.2.



Table 16.2

 FRP for pultruded FRP and aramid fibre rope (See Clause 16.5.3.) Application

 FRP

AFRP reinforcement in concrete and NSMR

0.65

AFRP in externally bonded applications

0.55

AFRP and aramid fibre rope tendons for concrete and timber components

0.60

CFRP reinforcement in concrete

0.80

CFRP in externally bonded applications and NSMR

0.80

CFRP tendons

0.80

GFRP reinforcement in concrete

0.55

GFRP in externally bonded applications and NSMR

0.70

GFRP tendons for concrete components

0.55

GFRP tendons for timber decks

0.70

16.6 Fibre-reinforced concrete 16.6.1 General Randomly distributed fibre reinforcement shall be permitted in deck slabs, barrier walls, and surfacing of stressed log bridges for the control of cracks that develop in concrete during its early life. Its use in other applications shall require Approval. 

16.6.2 Fibre volume fraction The fibre volume fraction shall be such that the residual strength index, Ri , is at least that specified by Table 16.3 for the particular application, where Ri is calculated as Ri = ARS/R where ARS = mean value of the average residual strength determined using the ASTM C 1399 test on at least five fibre-reinforced concrete beam specimens R

= mean value of the modulus of rupture determined by performing the ASTM C 78 test on at least five fibre reinforced concrete specimens

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Table 16.3 Minimum values of Ri for various applications



(See Clause 16.6.2.) Application

Minimum value of Ri

Barrier wall with one mesh of bars

0.25

Barrier wall with two meshes of bars

0.0*

Deck slab with one crack-control mesh

0.25

Deck slab with two crack-control meshes

0.0*

Surfacing of stressed log bridges

0.30

*Fibres not needed.

16.6.3 Fibre dispersion in concrete Fibres shall be mixed uniformly in concrete. The Plans shall specify that before a given mix of FRC is used in the structure, the uniformity of dispersion of the fibres shall be confirmed visually. As an additional measure, the possibility of non-uniform fibre dispersion shall be estimated by comparing the compressive strength of FRC with that of the corresponding plain concrete using 7-day compressive strength tests in accordance with CAN/CSA-A23.1. If the FRC mix has a mean compressive strength less than 90% of that of the corresponding plain concrete, engineering judgment shall be exercised to determine corrective measures.

16.7 Externally restrained deck slabs 

16.7.1 General An externally restrained deck slab supported on parallel longitudinal beams that complies with Clause 16.7.2, 16.7.3, or 16.7.4 and satisfies the following conditions need not be analyzed except for negative transverse moments due to loads on the overhangs and barrier walls, and for negative longitudinal moments in continuous span bridges: (a) The deck slab is composite, with parallel supporting beams in the positive moment regions of the beams. (b) The spacing of the supporting beams, S, does not exceed 3000 mm. (c) The total thickness of the deck slab, including that of the stay-in-place formwork, if present, t, is at least 175 mm and at least S/15. (d) The supporting beams are connected with transverse diaphragms or cross-frames at a spacing of not more than 8000 mm. (e) The deck slab is confined transversely by straps or a stay-in-place formwork in accordance with the applicable provisions of Clause 16.7.2, 16.7.3, or 16.7.4. (f) When the deck slab is confined by straps, the distance between the top of the straps and the bottom of the slab is between 25 and 125 mm, as shown in Figure 16.1. (g) The projection of the shear connectors in the deck slab, ts , is at least 75 mm, as shown in Figure 16.1, or additional reinforcement with at least the same shear capacity as that of the shear connectors is provided and the projection of the additional reinforcement into the slab is at least 75 mm. (h) The cover distance between the tops of the shear-connecting devices and the top surface of the deck slab is at least 75 mm when the slab is not exposed to moisture containing de-icing chemicals; otherwise, this cover distance is at least 100 mm or the shear-connecting devices have an Approved coating.

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(i) (j)

The fibre volume fraction in the cast-in-place concrete is in accordance with Clause 16.6.2. The deck slab contains appropriate tensile reinforcement for transverse negative moments resulting from loads on deck slab overhangs and loads on railings or barrier walls. (k) The transverse edges of the deck slab are stiffened by composite edge beams with a minimum flexural rigidity, EI, in the plane of the deck slab of 3.5Lu4 Nmm2, where Lu is the unsupported length of the edge beam, or, for an unsupported length of edge beam less than 4250 mm, the details of the transverse edge beams are as shown in Figure 16.2, 16.3, 16.4, or 16.5. (l) For continuous span bridges, the deck slab contains longitudinal negative moment reinforcement in at least those segments where the flexural tensile stresses in concrete for the SLS cases are larger than 0.6fcr , where fcr is calculated as follows:

fcr = 0.4 fc′ (m) The spacing of the reinforcement bars shall not exceed 300 mm. The diameter of reinforcement bars shall not be less than 15 mm. When the conditions specified in this Clause and the requirements specified in Clause 16.7.1, 16.7.2, or 16.7.3, as applicable, are not satisfied, the design of the externally restrained deck slab shall require Approval. 

16.7.2 Full-depth cast-in-place deck slabs The design of an externally restrained deck slab with full-depth cast-in-place construction shall meet the requirements of Clause 16.7.1 and the following requirements: (a) The top flanges of all adjacent supporting beams shall be connected by straps that are perpendicular to the supporting beams and either connected directly to the tops of the flanges, as in the case of the welded steel straps shown in Figure 16.6, or connected indirectly, as in the case of the partially studded straps shown in Figure 16.7; alternatively, the transverse confining system shall comprise devices that have been proved through Approved full-scale laboratory testing. (b) The spacing of straps, S , shall be not more than 1250 mm. (c) Each strap shall have a minimum cross-sectional area, A, in mm2, as follows:

where Fs

= 6.0 MPa for outer panels and 5.0 MPa for inner panels

E

= modulus of elasticity of the strap material

In the case of FRP straps, the main fibres shall be in the direction perpendicular to the supporting beams. (d) The direct or indirect connection of a strap to the supporting beams shall be designed to have a minimum shear strength in newtons of 200A. (e) In a negative moment region of a supporting beam, where the beam is not made composite, shear-connecting devices shall be provided on the beam in the vicinity of the straps, and have a minimum total shear strength in newtons of 200A (as shown, e.g., in Figure 16.8). As shown in Figure 16.7, such shear-connecting devices shall be within 200 mm of the nearest strap. (f) The deck slab shall have a crack-control orthogonal assembly of GFRP bars placed near the bottom of the slab, with the area of the cross-section of the GFRP bars in each direction being at least 0.0015t mm2/mm. When steel straps are welded to steel girders in negative moment regions, the fatigue of the girder shall be considered. When the conditions specified in Clause 16.7.1 and the requirements specified in this Clause are not satisfied, the design of the slab shall require Approval.

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© Canadian Standards Association

16.7.3 Cast-in-place deck slabs on stay-in-place formwork The design of an externally restrained deck slab with cast-in-place construction on stay-in-place formwork shall meet the requirements of Clause 16.7.1 and the following requirements: (a) The design of the formwork shall take into account its anticipated handling and anticipated conditions during construction. (b) The effective span of the formwork shall be taken as the distance between the edges of the supporting beams plus 150 mm. (c) The deflection of the formwork during construction shall not exceed 1/240 of the effective span of the formwork. (d) The ends of the formwork shall be supported on beams in such a manner that after placement of concrete topping a support length of at least 75 mm shall be provided under the lower portions of the formwork. Such support shall be within 25 mm of the closer edges of the supporting beams. (e) The top flanges of all adjacent supporting beams shall be connected by external straps or the formwork itself. (f) When the deck slab is confined by straps, the straps and their connections shall be designed to satisfy the requirements specified in Items (a) to (e) of Clause 16.7.2. (g) When the deck slab is restrained by a formwork, the concept shall have been verified by tests on full-scale models. In addition, the minimum area of cross-section of the formwork, in mm2/mm, across a section parallel to the beams, A f , shall be calculated as follows:

Af =

FsS 2 Et

where Fs

= 6.0 MPa for outer panels and 5.0 MPa for inner panels

E

= modulus of elasticity of the material of the formwork in the direction perpendicular to the supporting beams

(h) When the deck slab is restrained by a formwork, the direct or indirect connection of the formwork to the supporting beams shall have been proved by full-scale tests to have a shear strength in N/mm of at least 200Af . (i) When the formwork is of precast concrete construction, it shall contain a crack-control orthogonal assembly of GFRP bars placed at its mid-depth, with an area of cross-section of GFRP bars in each direction equal to 0.0015t mm2/mm. (j) When it is of precast construction, the formwork panel shall have a maximum thickness of 0.5t. (k) When it is of precast construction, the upper surface of the formwork panel shall be clean, free of laitance, and roughened to an amplitude of 2 mm at a spacing of nearly 15 mm. (l) The cast-in-place concrete shall have a crack-control orthogonal assembly of GFRP bars placed in the middle of the cast-in-place slab, with the area of the cross-section of the GFRP bars in each direction being at least 0.0015tc mm2/mm. When the conditions specified in Clause 16.7.1 and the requirements specified in this Clause are not satisfied, the design of the slab shall require Approval.

16.7.4 Full-depth precast concrete deck slabs The design of an externally restrained deck slab with full-depth precast concrete construction shall require Approval.

706

May 2010 (Replaces p. 706, November 2006)

© Canadian Standards Association

Canadian Highway Bridge Design Code

75 mm (min.)

t = 175 mm (min.)

ts = 75 mm (min.) 25 to 125 mm

Strap attached to top flanges of supporting beams

Figure 16.1 Distance between the deck slab and the top of the supporting beam (See Clause 16.7.1.)

As = 0.048t2 or AFRP = 0.048t2 fs fy fFRP fFRP (fully anchored reinforcement)

As = 0.028t2 or AFRP = 0.028t2 Es EFRP

t 2t

Strap

500 mm

200 mm (max.)

Figure 16.2 Detail of transverse edge stiffening (See Clause 16.7.1.)

November 2006

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CAN/CSA-S6-06

© Canadian Standards Association

75 mm (min.)

t

1.5t

200 mm 300 mm

Minimum C200 × 21 connected to supporting beams, with two 22 mm diameter studs at 300 mm (web of channel connected to top flanges of supporting beams)

Figure 16.3 Detail of transverse edge stiffening (See Clause 16.7.1.)

75 mm (min.)

t

1.5t Minimum W200 × 52 connected to supporting beams, with two 22 mm diameter studs at 300 mm

200 mm Approx. 300 mm

Figure 16.4 Detail of transverse edge stiffening (See Clause 16.7.1.)

708

November 2006

© Canadian Standards Association

Canadian Highway Bridge Design Code

t

1.5t As = 0.028t2 or AFRP = 0.028t2 Es EFRP

d (min. 500 mm)

300 mm

As = 0.008bd or AFRP = 0.008bd fs fy fFRP fFRP

Figure 16.5 Detail of transverse edge stiffening (See Clause 16.7.1.)

Strap attached to top flanges of supporting beams

Figure 16.6 External transverse restraining system consisting of connected straps (See Clause 16.7.2.)

November 2006

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CAN/CSA-S6-06

© Canadian Standards Association

75 to 100 mm

Partially studded steel strap Steel or concrete girder Partially studded steel strap

100 to 200 mm (max.)

Strap tied to nearest shear connector in precast beam

Shear connector in precast beam

Figure 16.7 External transverse confining system consisting of indirectly connected partially studded straps (See Clause 16.7.2.)

Shear connectors (bolted or welded) attached to girder flange (only near the studded strap), providing a total shear strength of 200A N

Steel strap welded to flange of supporting beam

Partially studded steel strap

CL Intermediate support Region of -ve moment in supporting beam

Figure 16.8 External transverse confining system in longitudinal negative moment regions (See Clause 16.7.2.)

710

November 2006

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

16.8 Concrete beams and slabs 16.8.1 General Except as specified in this Section, the resistance and deformations of concrete beams, slabs, and deck slabs reinforced with FRP tendons, bars, or grids, corresponding to the various limit states, shall be calculated in accordance with Section 8. The resistance at ULS for beams and slabs with FRP bars or grids in multiple layers shall be calculated by taking account of the linear variation of strain through the depth of the member, ensuring that the stresses in the reinforcement are consistent with Clause 16.8.3. The maximum compressive concrete strains in beams and slabs due to factored loads shall not exceed the limiting strain specified in Section 8. Internally restrained deck slabs shall be designed in accordance with Clause 16.8.8.

16.8.2 Deformability and minimum reinforcement 16.8.2.1 Design for deformability For concrete components reinforced with FRP bars or grids, the overall performance factor, J, shall be at least 4.0 for rectangular sections and 6.0 for T-sections, with J calculated as follows:

J=

Mult y ult Mc y c

where Mult

= ultimate moment capacity of the section

ult = Mc

curvature at Mult = moment corresponding to a maximum compressive concrete strain in the section of 0.001

c =

curvature at Mc

16.8.2.2 Minimum flexural resistance The factored resistance, Mr , shall be at least 50% greater than the cracking moment, Mcr , as specified in Clause 8.8.4.4. This requirement may be waived if the factored resistance, Mr , is at least 50% greater than the factored moment, Mf . If the ULS design of the section is governed by FRP rupture, Mr shall be greater than 1.5Mf . The principles for calculating Mcr and Mr shall be consistent with those specified in Clause 8.8, except that stresses in FRP bars at different levels, if present, shall be calculated by assuming a linear distribution.

16.8.2.3 Crack-control reinforcement When the maximum tensile strain in FRP reinforcement under full service loads exceeds 0.0015, cross-sections of the component in maximum positive and negative moment regions shall be proportioned in such a way that the crack width does not exceed 0.5 mm for members subject to aggressive environments and 0.7 mm for other members, with the crack width calculated as follows:

w cr = 2

fFRP h2 2 kb dc 2 + ( s / 2) EFRP h1

The value of kb shall be determined experimentally, but in the absence of test data may be taken as 0.8 for sand-coated and 1.0 for deformed FRP bars. In calculating dc , the clear cover shall not be taken greater than 50 mm.

May 2010 (Replaces p. 711, November 2006)

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S6S1-10

© Canadian Standards Association

16.8.3 Non-prestressed reinforcement The maximum stress in FRP bars or grids under loads at SLS shall not be more than FSLS fFRPu , where FSLS is as follows: (a) for AFRP: 0.35; (b) for CFRP: 0.65; and (c) for GFRP: 0.25.

16.8.4 Development length for FRP bars and tendons 

16.8.4.1 General The development length, d , for FRP bars in tension shall be calculated as follows:

where fFRP = stress in the tension reinforcement at ULS In addition, d shall not be taken as less than 250 mm. All of the variables in this equation shall be in accordance with Clause 8.15.2.2, except as follows: (a) The variable k4 is the bar surface factor, being the ratio of the bond strength of the FRP bar to that of a steel deformed bar with the same cross-sectional area as the FRP bar, but not greater than 1.0. In the absence of experimental data, k4 shall be taken as 0.8. (b) The variable EFRP is the modulus of elasticity of the FRP bar. (c) The term (dcs + Ktr EFRP /Es ) shall not be taken greater than 2.5db . (d) The bond strength of the FRP bar shall be determined by testing or taken to be the bond strength specified by the manufacturer of the bar.

16.8.4.2 Splice length for FRP bars The splice length for FRP bars in tension shall be 1.3d , where d is calculated in accordance with Clause 16.8.4.1. Spliced FRP bars shall not be separated by more than 150 mm.

16.8.5 Development length for FRP grids For FRP grids in which the intersecting orthogonal bars have been demonstrated to be fully anchored, the development length shall include at least two transverse bars of the grid lying perpendicular to the direction of the force under consideration.

16.8.6 Tendons 16.8.6.1 Supplementary reinforcement A structure incorporating concrete beams or slabs with FRP tendons shall contain supplementary reinforcement capable of sustaining the unfactored dead loads or have alternative load paths such that the failure of one beam or a portion of a slab will not lead to progressive collapse of the structure.

16.8.6.2 Stress limitations for tendons For straight tendons, the maximum stress at jacking and transfer shall not exceed the values specified in Table 16.4. For curved tendons, the maximum stresses at jacking and transfer shall be those specified in Table 16.4, reduced by an amount determined from tests. FRP tendons shall be stressed to provide a minimum effective prestress of 75% of the stresses at transfer. The maximum SLS stresses after all prestress losses shall not exceed the FSLS values specified in Clause 16.8.3.

712

May 2010 (Replaces p. 712, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

The maximum stress in the tendons under factored loads at ULS, fps , computed using a method based on strain compatibility, shall not exceed FRP fFRPu , where the resistance factor FRP is as specified in Clause 16.5.3.

Table 16.4 Maximum permissible stresses in FRP tendons at jacking and transfer for concrete beams and slabs for pretensioning and post-tensioning systems (See Clauses 16.8.6.2 and 16.9.4.)



Tendon

At jacking

At transfer

AFRP

0.40fFRPu

0.35fFRPu

CFRP

0.70fFRPu

0.65fFRPu

GFRP

0.30fFRPu

0.25fFRPu

16.8.6.3 Capacity of anchors When tested in an unbonded condition, anchors for post-tensioning tendons shall be capable of developing a tendon force at least 50% higher than the jacking force, but not more than 90% of the specified tensile strength of the tendons, without exceeding the anticipated set. After tensioning and seating, anchors shall sustain applied loads without slippage, distortion, or other changes that result in loss of prestress. The Plans shall specify that at least two anchors are to be tested to confirm this requirement.

16.8.6.4 End zones in pretensioned components The end zones of pretensioned concrete components shall be reinforced against splitting unless it can be demonstrated that such reinforcement is unnecessary.

16.8.6.5 Protection of external tendons External tendons comprising glass or aramid fibres shall be protected against ultraviolet rays by encasing them in protective sheaths; carbon fibre external tendons with ultraviolet-susceptible matrices shall also be similarly protected. Aramid fibre ropes shall be protected by sheaths and watertight anchors against the ingress of moisture. 

16.8.7 Design for shear For concrete beams reinforced with steel or FRP longitudinal reinforcement, and with steel or FRP stirrups, the factored shear resistance, Vr, shall be calculated as follows: Vr = Vc + Vst + Vp where Vst = Vs or VFRP (in accordance with the type of stirrups used in the beam) Clause 8.9.3 shall be used to calculate Vc , Vs , and Vp , except as follows: (a) Instead of calculating Vc in accordance with Clause 8.9.3.4, the following equation shall be used:

Vc = 2.5bfc fcr bv dlong The effective shear depth, dlong , shall be calculated in accordance with Clause 8.9.1.5, and  shall be calculated in accordance with Clause 8.9.3.7, after using the value of  x in Clause 16.8.7(b).

May 2010 (Replaces p. 713, November 2006)

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S6S1-10

© Canadian Standards Association

(b) Instead of calculating  x in accordance with Clause 8.9.3.8, one of the following equations shall be used: Mf + Vf − Vp + 0.5Nf − Apfpo d (i) e = long ≤ 0.003 x 2 E s As + E p Ap

(

(

(ii)

ex =

)

)

Mf + Vf − Vp + 0.5Nf − AFRP fpo dlong

(

2 (E s As + EFRP AFRP )

)

≤ 0.003

(c) For the factored shear resistance carried by FRP shear reinforcement, VFRP , the following equations shall be used: (i) for components with transverse reinforcement perpendicular to the longitudinal axis:

VFRP =

fFRP A v s v dlong cot q s

(ii) for components with transverse reinforcement inclined at an angle  to the longitudinal axis:

VFRP =

fFRP A v s v dlong (cot q + cot a ) sin a

s For the equations in Items (i) and (ii),  shall be obtained from Clause 8.9.3.7 for the general method; the coefficient  FRP shall be as specified in Clause 16.5.3; and  v shall be the smaller of the values obtained from the following two equations: sv =

(0.05r / ds + 0.3)fFRPbend 1.5

= EvFRP v where

v = 0.004 (d) The minimum amount of shear reinforcement, Av,min , shall be calculated as follows: Av,min = 0.06 fc′

bw s sv

where  v is as specified in Item (c).

16.8.8 Internally restrained cast-in-place deck slabs 

16.8.8.1 Design by empirical method The requirements of Clause 8.18 pertaining to cast-in-place deck slabs shall apply to cast-in-place deck slabs with FRP bars or grids, except that when the deck slab is designed using the empirical method of Clause 8.18.4, the following requirements shall be met in lieu of those specified in Items (a) and (c) of Clause 8.18.4.2: (a) the deck slab shall contain two orthogonal assemblies of FRP bars, with the clear distance between the top and bottom transverse bars being at least 55 mm. The diameter of reinforcement bars shall not be less than 15 mm; (b) for the transverse FRP bars in the bottom assembly, the minimum area of cross-section in mm2/mm shall be 500ds /EFRP ; and (c) the longitudinal bars in the bottom assembly and the transverse and longitudinal bars in the top assembly shall be of GFRP with a minimum s of 0.0035.

714

May 2010 (Replaces p. 714, November 2006)

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Consistent with the requirements of Clause 8.18.1, the requirements of Clause 16.8.2.3 shall be waived for decks designed using the empirical method. The edge-stiffening details shall be as shown in Figures 16.2 to 16.5. 

16.8.8.2 Design for flexure For cast-in-place deck slabs with FRP bars or tendons designed for flexure, the requirements of Clauses 16.8.2 to 16.8.6 shall apply. In addition, the requirements of Clause 8.18.5 shall be satisfied for diaphragms. The distribution reinforcement shall be designed in accordance with Clause 8.18.7. In addition, the spacing of the reinforcement in each direction shall not exceed 300 mm. The diameter of reinforcement bars shall not be less than 15 mm.

16.9 Stressed wood decks 16.9.1 General Clauses 16.9.2 to 16.9.6 shall apply to stress-laminated wood decks and stressed log bridges that are post-tensioned with FRP or fibre rope tendons.

16.9.2 Post-tensioning materials 16.9.2.1 Tendons GFRP, AFRP, and aramid ropes shall be permitted as tendons in stressed wood decks. The design of stressed laminated wood decks shall comply with Section 9 (with the exception of Clause 9.23.3.4) and Clauses 16.9.2.2 to 16.9.6.

16.9.2.2 Anchors Anchors shall be capable of developing a tendon force at least 50% higher than the jacking force. The Plans shall specify that at least two anchors are to be tested to confirm this requirement.

16.9.2.3 Stress limitations At initial stressing, the stresses shall not exceed 0.35fFRPu for GFRP tendons or 0.40fFRPu for AFRP and aramid rope tendons.

16.9.3 Post-tensioning system For stressed log bridges, the post-tensioning system shall be external or internal (the external system is shown in Figure 16.9). For stress-laminated wood decks, the post-tensioning system shall be as shown in Figure 9.5 or 9.6, except that the tendons shall comprise GFRP, AFRP, or aramid ropes. When lower tendons in decks with external post-tensioning are exposed to damage from flowing debris, they shall be suitably protected.

May 2010 (Replaces p. 715, November 2006)

715

S6S1-10

© Canadian Standards Association

Steel channel bulkhead

Safety nut

Anchor

Fibre tendon with protective tubing

Anchorage plate Wood bearing block

Anchorage nut 5 mm (minimum)

Figure 16.9 Post-tensioning system for stressed log bridges (See Clause 16.9.3.)

16.9.4 Stressing procedure The initial post-tensioning forces in the tendons shall be such as to bring the average interface pressure between wood laminates or logs to approximately 0.8 MPa, regardless of the species concerned. These forces shall be reduced 12 to 24 h after initial post-tensioning to establish an average interface pressure of 0.35 to 0.44 MPa, at which level the stresses in the tendons shall not exceed the relevant values specified in Table 16.4 for post-tensioning at transfer.

16.9.5 Design of bulkheads Stressed wood decks shall incorporate steel distribution bulkheads, as specified in Clause 9.23.4, except that the factored bearing resistance, calculated in accordance with Clause 9.23.4.2, shall be for the reduced post-tensioning forces specified in Clause 16.9.4.

16.9.6 Stressed log bridges 16.9.6.1 General A stressed log bridge shall be constructed of logs (a) that are (i) new; or (ii) used but structurally sound; and (b) whose exposed surfaces have been suitably treated in accordance with Section 9.

16.9.6.2 Log dimensions The logs in a stressed log bridge shall meet the following requirements: (a) the ratio of the largest to the smallest diameter of a log shall be not more than 1.10; (b) the out-of-straightness of a log shall be not more than 0.003 times its length; (c) the end faces of a log shall be perpendicular to its axis to within an angular tolerance of 5°; and (d) the logs shall be trimmed longitudinally so as to provide, at any transverse cross-section, two opposed faces that are parallel within an accuracy of 2°.

716

May 2010 (Replaces p. 716, November 2006)

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

© Canadian Standards Association

16.9.6.3 Splicing at butt joints As shown in Figure 16.10, all butt joints shall be spliced by hot-dipped galvanized steel nail-plates with a minimum thickness of 1.5 mm. The nail-plates shall be installed by using a hydraulic jack or other Approved means to apply uniform pressure. Galvanized nail-plate 1.5 mm (minimum) thick

0.7b (min.)

Height b

2b (minimum)

Figure 16.10 Spliced butt joint for logs (See Clause 16.9.6.3.)

16.9.6.4 Frequency of butt joints The butt joints shall be staggered in such a way that within any band with a width of 1 m measured along the logs, a butt joint shall not occur in more than one out of four adjacent logs on each side of the log with a butt joint.

16.9.6.5 Holes in logs for an internal system The diameter of the holes drilled in the logs for an internal post-tensioning system shall be less than or equal to 20% of the minimum diameter of the logs.

16.9.6.6 Support anchorage A stressed log bridge shall be secured to the substructure by steel bars in accordance with the requirements of Clause 9.23.5.5 for stress-laminated wood decks.

16.9.6.7 Surfacing The top of a stressed log bridge shall be surfaced by hot-mix asphalt or FRC incorporating low modulus polymer fibres. A fibre-reinforced concrete surfacing may be assumed to be acting compositely with the logs if the smallest thickness of concrete is not more than 50 mm.

16.9.6.8 Flexural resistance and stiffness The factored flexural resistance, Mr , of a stressed log bridge shall be calculated in accordance with Clause 9.6.1, except that the value of fbu shall be obtained from Table 9.17, which shall also be used for obtaining the modulus of elasticity of the logs.

May 2010 (Replaces p. 717, November 2006)

717

S6S1-10



© Canadian Standards Association

16.10 Barrier walls A barrier wall that has the details shown in Figure 16.11 and satisfies the following conditions shall be deemed to have met the Performance Level 3 requirements of Section 12: (a) on the traffic side, the wall has a GFRP grid or an orthogonal assembly of GFRP bars providing a factored strength of 330 N per millimetre length of the wall in the vertical direction and 240 N per millimetre length of the wall in the horizontal direction; (b) the spacing of the bars in the GFRP grid or orthogonal assembly on the traffic side is not more than 300 mm; (c) the wall is reinforced with (i) one planar GFRP grid or an orthogonal assembly of GFRP bars near the surface, as shown in Figure 16.11, and FRC is used in accordance with Clause 16.6; or (ii) two layers of planar GFRP grid or two orthogonal assemblies of GFRP bars (in which case FRC is not needed); (d) if a planar GFRP grid or an orthogonal assembly of GFRP bars is provided away from the traffic side, it comprises bars of a diameter of at least 15 mm, at a spacing of 300 mm in the horizontal and vertical directions; (e) if only one planar GFRP grid or orthogonal assembly of GFRP bars is used, the wall is provided at mid-thickness near its top with two 19 mm diameter steel bars or two 15 mm diameter GFRP bars, as shown in Figure 16.11; (f) the wall is anchored to the slab by double-headed steel bars 19 mm in diameter and 500 mm long, or by bent GFRP bars whose performance has been established by Approved full-scale tests, at a spacing of 300 mm; (g) the spacing of the bars and anchors is reduced by half for the following lengths of the wall: (i) 1.2 m on each side of a joint in the wall; (ii) 1.2 m on each side of a luminaire embedded in the wall; and (iii) 1.2 m from the free vertical edges of the wall; and (h) the cover to GFRP bars (if any) meets the requirements of Clause 16.4.4 and the cover to double-headed bars (if any) meets the requirements of Clause 8.11.2.2. Barrier walls for Performance Levels 1, 2, and 3 with details other than those shown in Figure 16.11 may be used if their performance has been established by Approved full-scale tests.

718

May 2010 (Replaces p. 718, November 2006)

© Canadian Standards Association

Canadian Highway Bridge Design Code

175

80

19 mm diameter steel or GFRP bars at mid-depth

180

100 100

19 mm diameter, 500 mm long double-headed tension bar of steel at 300 mm centres

800 GFRP grid or orthogonal assembly of GFRP bars

1025

50 250

90

Note: All dimensions are in millimetres.

Figure 16.11 Cross-section of a barrier wall reinforced with GFRP (See Clause 16.10.)

16.11 Rehabilitation of existing concrete structures with FRP 16.11.1 General Clause 16.11 applies to existing concrete structures that have an fc‘ of less than or equal to 50 MPa and are strengthened with FRP comprising externally bonded systems or NSMR. If the concrete cover is less than 20 mm, NSMR shall not be used. Rehabilitation of concrete structures with an fc‘ of more than 50 MPa shall require Approval. For situations where the concrete component contains corroded reinforcing steel, the causes of the corrosion shall be addressed and the corrosion-related deterioration shall be repaired before application of any FRP strengthening system.

November 2006

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© Canadian Standards Association

For concrete structures strengthened with FRP, the Plans shall provide details and specifications relevant to the following and as specified in Annexes A16.1 and A16.2: (a) identification of the FRP strengthening systems and protective coatings; (b) concrete preparation; (c) shipping, storage, and handling of the FRP strengthening systems; (d) installation of the FRP strengthening systems, including (i) the spacing and positioning of the components; (ii) the locations of overlaps and multiple plies; (iii) installation procedures; and (iv) constraints for climatic conditions; (e) the curing conditions of the strengthening systems; (f) the quality control of the strengthening systems, as specified in Annex A16.2; (g) staff qualifications; (h) material inspection before, during, and after completion of the installation; and (i) system maintenance requirements. Before a rehabilitation strategy is developed, an assessment of the existing structure or elements shall be conducted in accordance with Section 14. Only those structures that have a live load capacity factor, F, of 0.5 or greater as specified in Clause 14.15.2.1 shall be strengthened. Consideration shall be given to the fact that FRP strengthening can result in a change in failure mode or in-service behaviour of a member or its adjacent members as a consequence of the increased loads or stresses.

16.11.2 Flexural and axial load rehabilitation 16.11.2.1 General Clause 16.11.2 covers externally bonded FRP systems (a) placed on or near the tension face of steel-reinforced concrete flexural members, with fibres oriented along the length of the member to provide an increase in flexural strength; (b) placed on the external perimeter of concrete columns to enhance the axial load capacity of the columns; and (c) for seismic upgrading. Clause 16.11.2 shall not be used for seismic upgrading to enhance the flexural strength of members in the expected plastic hinge regions of ductile moment frames resisting seismic loads and shall not be used for the flexural strengthening of deep beams.

16.11.2.2 Assumptions for SLS and FLS calculations In addition to being based on the conditions of equilibrium and compatibility of strains, SLS and FLS calculations shall be based on the assumptions of Clause 8.8.2 and on the assumption that strain changes in the FRP strengthening system are equal to the strain changes in the adjacent concrete.

16.11.2.3 Assumptions for ULS calculations In addition to being based on the conditions of equilibrium and compatibility of strains, ULS calculations shall be based on the material resistance factors specified in Clauses 8.4.6 and 16.5.3, the assumptions of Clause 8.8.3, the assumption that strain changes in the FRP strengthening systems are equal to the strain changes in the adjacent concrete, and the assumption that the contribution of FRP in compression will be neglected. For an externally bonded flexural strengthening system, the maximum value of the strain in the FRP shall not exceed 0.006.

720

November 2006

© Canadian Standards Association

Supplement No. 1 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

16.11.2.4 Flexural components 16.11.2.4.1 Failure modes For a section strengthened with FRP systems, the following flexural failure modes shall be investigated at ULS: (a) crushing of the concrete in compression before rupture of the FRP or yielding of the reinforcing steel; (b) yielding of the steel followed by concrete crushing before rupture of the FRP in tension; (c) yielding of the steel followed by rupture of the FRP in tension; (d) in the case of members with internal prestressing, additional failure modes controlled by the rupture of the prestressing tendons; and (e) peeling failure or anchorage failure of the FRP system at the cut-off point.

16.11.2.4.2 Flexural resistance to sustained and fatigue loads At SLS and/or FLS, stresses shall be calculated based on elastic analysis. The effect of the FRP system on the serviceability may be assessed using transformed section analysis. The initial stresses and strains related to unfactored dead loads in a beam before strengthening shall be considered. In addition to satisfying the requirements of Clause 8.5.2 for SLS and Clause 8.5.3 for FLS, the stress level in the FRP system due to all dead loads after strengthening and SLS live loads shall not exceed FSLS fFRPu , where the value of FSLS is obtained from Clause 16.8.3.

16.11.2.4.3 Factored flexural resistance The factored flexural resistance shall be calculated in accordance with Clause 16.11.2.3.

16.11.2.4.4 Anchorage lengths for flexure For externally-bonded FRP strengthening systems, the anchorage length beyond the point where no strengthening is required shall not be less than a , calculated as follows:

 a = 0.5 EFRP tFRP In addition, the anchorage length shall be at least 300 mm or the FRP shall be suitably anchored. For NSMR, the anchorage length, d , beyond the point where no strengthening is required shall be calculated in accordance with Clause 16.8.4.1.

16.11.2.5 Compression components 16.11.2.5.1 General For FRP-strengthened columns subjected to combined flexure and axial compression, the factored resistance shall be calculated in accordance with Clause 16.11.2.3.

16.11.2.5.2 Slenderness effects The slenderness effects shall be accounted for in accordance with Clauses 8.8.5.2 and 8.8.5.3.

16.11.2.5.3 Maximum factored axial resistance For columns with FRP systems bonded to the external perimeter that meet the requirements of Clause 16.11.2.3, the factored axial resistance, Pr , shall be less than or equal to 0.80Po . The confined concrete compressive strength determined in accordance with Clause 16.11.2.5.6 may be used to evaluate Po .

16.11.2.5.4 Biaxial loading An analysis based on stress and strain compatibility for a loading condition of compression and biaxial bending shall be used to design the FRP strengthening system.

May 2010 (Replaces p. 721, November 2006)

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16.11.2.5.5 Transverse reinforcement If the existing steel transverse reinforcement does not meet the requirements of Clause 8.14.4, FRP transverse reinforcement shall be provided in accordance with Clause 16.11.3. 

16.11.2.5.6 Axial load capacity enhancement The compressive strength of the confined concrete, fc‘c , shall be calculated as follows: fc‘c = fc‘ + 2fFRP The confinement pressure due to FRP strengthening at the ULS, fF RP , shall be calculated as follows:

fFRP =

2fFRP fFRPutFRP Dg

For columns with circular cross-sections, Dg is the diameter of the column; for columns with rectangular cross-sections with aspect ratios less than or equal to 1.5 and a smaller cross-sectional dimension not greater than 800 mm, Dg is equal to the diagonal of the cross-section. For columns with other polygonal cross-sections, Dg is equal to the diameter of the circumscribed circle. The confinement pressure at the ULS shall be designed to be between 0.1fc‘ and 0.33fc‘.

16.11.3 Shear rehabilitation with externally bonded FRP systems 

16.11.3.1 General Clause 16.11.3 covers the proportioning of externally bonded FRP systems to increase the shear capacity of reinforced concrete beams and columns. The shear-strengthening scheme shall be of the type in which the fibres are oriented perpendicularly or at an angle  to the member axis. The shear reinforcement shall be anchored by suitable means in the compression zone in accordance with one of the following schemes: (a) the shear reinforcement shall be fully wrapped around the section, as shown in Figure 16.12; (b) the anchorage to the shear reinforcement near the compression flange shall be provided by additional horizontal strips, as shown in Figure 16.12; and (c) the anchorage shall be provided in the compression zone, as shown in Figure 16.12. However, an alternative anchorage scheme may be used if Approved.

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© Canadian Standards Association

Fully wrapped section

Anchorage with horizontal strips

Anchorage inside the slab

Figure 16.12 Anchorage methods in the compression zone of externally bonded FRP shear reinforcement (See Clause 16.11.3.1.) 

16.11.3.2 Factored shear resistance For reinforced concrete members with rectangular sections or T-sections and FRP reinforcement anchored in the compression zone of the member, the factored shear resistance, Vr , shall be calculated as follows: Vr = Vc + Vs + VFRP Vc and Vs shall be calculated in accordance with Clause 8.9.3 and VFRP shall be calculated as follows:

VFRP =

fFRP EFRP eFRPe AFRP dFRP (cot q + cot a ) sin a sFRP

where

FRPe = 0.004  0.75FRPu (for completely wrapped sections) = V FRPu  0.004 (for other configurations) For continuous U-shaped configurations of the FRP reinforcement, the bond-reduction coefficient, V, shall be calculated as follows:

kV =

k1k2Le ≤ 0.75 11900e FRPu

where

k1 = (fc′ / 27 )

2 /3

k2 =

dFRP − Le dFRP

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723

S6S1-10

Le =

© Canadian Standards Association

23300

(tFRP EFRP )0.58

For prestressed concrete components, Vr shall be the sum of Vc , Vs , Vp , and VFRP . The equations in this Clause shall be used to calculate VFRP . The general method of Clause 8.9.3 shall be used to calculate Vc , Vs , and Vp. For components with non-rectangular or non-T cross-sections, a rigorous analysis or test shall guide the design. 

16.11.3.3 Spacing and strengthening limits The spacing of FRP bands shall be not more than sFRP, calculated as follows:

(

sFRP = wFRP + d FRP / 4

)

The total factored shear resistance subsequent to FRP strengthening, Vr , shall not exceed the value given in Clause 8.9.3.3.

16.12 Rehabilitation of timber bridges 16.12.1 General Clause 16.12 applies to beams of timber and stringer grades strengthened with GFRP sheets or bars. The bars, if present, shall be near-surface mounted or embedded in holes in timber. The empirical methods specified in Clause 16.12 may be used to determine the strengthof timber beams strengthened with GFRP sheets or bars for flexure, shear, or both. Although the requirements of Clause 16.12 are intended for GFRP bars and sheets, AFRP and CFRP bars and sheets may be used in place of GFRP bars and sheets. If the strength for either flexure or shear needs to be more than is provided by the empirical methods of Clause 16.12, experimental evidence shall be used to determine the amount of FRP reinforcement. The procedures for handling, storage, and protection of FRP sheets and bars shall be the same as those specified in Clause 16.4.8. The Plans shall provide details and specifications relevant to the following and as specified in Annexes A16.1 and A16.2: (a) identification of the FRP strengthening systems and protective coatings; (b) surface preparation; (c) shipping, storage, and handling of the FRP strengthening systems; (d) installation of the FRP strengthening systems, including (i) spacing and positioning of the components; (ii) locations of overlaps and multiple plies; (iii) installation procedures; and (iv) constraints for climatic conditions; (e) the curing conditions of the strengthening systems; (f) the quality control of the strengthening systems, as specified in Annex A16.2; (g) staff qualifications; (h) material inspection before, during, and after completion of the installation; and (i) system maintenance requirements. Before a rehabilitation strategy is developed, an assessment of the existing structure or elements shall be conducted in accordance with Section 14.

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Canadian Highway Bridge Design Code

16.12.2 Strengthening for flexure 16.12.2.1 Flexural strengthening with GFRP sheets When the following minimum conditions for strengthening with GFRP sheets are satisfied, the bending strength for beam and stringer grades used for the evaluation shall be KbFRP fbu , in which KbFRP shall be obtained from Table 16.5 and fbu from Table 9.13: (a) The minimum fibre volume fraction of the GFRP system in the direction of the span of the beam is 30%. (b) The GFRP sheet on the flexural tension face of the beam covers at least 90% of the width of the beam and has a minimum thickness of 0.1 mm. (c) The adhesive used for bonding the GFRP sheets to the timber beam is compatible with the preservative treatment used on the timber. (d) In the longitudinal direction of the beam, the GFRP sheets extend as close to the beam supports as possible. (e) The adhesive used for bonding the GFRP sheets to the timber beam is compatible with the expected volumetric changes of the timber.

Table 16.5 Values of KbFRP (See Clause 16.12.2.) Grade of original beam

KbFRP

SS

*

No. 1

1.2

No. 2

1.5

*This value shall be 1.05 if the beam is not strengthened for shear and 1.1 if the beam is strengthened for shear.

16.12.2.2 Flexural strengthening with GFRP NSMR When the following minimum conditions for strengthening with GFRP NSMR are satisfied, the bending strength for beam and stringer grades used for the evaluation shall be KbFRP fbu , in which KbFRP shall be obtained from Table 16.5 and fbu from Table 9.13: (a) The minimum fibre volume fraction of GFRP bars is 60%. (b) There are at least two bars within the width of the beam. (c) The total cross-sectional area for all bars on a beam is at least 0.002 times the cross-sectional area of the timber component. (d) As shown in Figure 16.13, each bar is embedded in a groove (preferably with a rounded end). The depth of each groove is between 1.6 to 2.0 times db , the bar diameter; the width of each groove is not less than db plus 5 mm; the edge distance of the outer groove is not less than 25 mm and not less than 2db ; and the clear spacing between grooves is not less than 25 mm and not less than 3db . (e) The grooves in the beams are cleaned with pressurized air to remove any residue before the GFRP bars are embedded in them. (f) The adhesive used for bonding the GFRP bars to the timber beam is compatible with the preservative treatment used on the timber and with the expected volumetric changes of the timber. (g) In the longitudinal direction of the beam, the GFRP bar extends as close to the beam support as possible. (h) Each GFRP bar is held in place as close to the tip of the groove as possible.

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GFRP bar (typ.) with diameter db

Depth of groove

Edge distance

Clear distance Width of between groove grooves

Figure 16.13 Cross-section of a timber beam with GFRP NSMR (See Clause 16.12.2.2.)

16.12.3 Strengthening for shear 16.12.3.1 Shear strengthening with GFRP sheets When the following minimum conditions for shear strengthening with GFRP sheets are satisfied, the shear strength for beam and stringer grades used for the evaluation shall be assumed to be KvFRP fvu , in which KvFRP shall be taken as 2.0 and fvu shall be obtained from Table 9.13: (a) The minimum fibre volume fraction of the GFRP sheets along their axes is 30% and the sheets have a minimum thickness of 0.1 mm. (b) Horizontal splits in beams, if present, are closed by a mechanical device before the application of the GFRP sheets. (c) The GFRP sheets have at least the same width as the width of the cross-section of the beam (see Figure 16.14(a)). (d) As shown in Figure 16.14(a), the GFRP sheet is inclined to the beam axis at an angle of 45 ± 10° from the horizontal. (e) The top of the inclined GFRP sheet is as close to the centreline of the beam support as possible. (f) The adhesive used for bonding the GFRP sheets to the timber beam is compatible with the preservative treatment used on the timber and with the expected volumetric changes of the timber. (g) The top of the inclined GFRP sheet extends up to nearly the top of the beam. (h) The lower end of the inclined GFRP sheet extends to the bottom of the beam if no dap is present (see Figure 16.14(a)). If there is a dap, the lower end is wrapped around the bottom and extends to at least half the width of the beam. In the latter case, the corner of the beam is rounded to a minimum radius of 12.5 mm to provide full contact of the sheet with the beam (see Figure 16.14(b)).

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CL

Canadian Highway Bridge Design Code

Horizontal split closed mechanically

45 ± 10°

Not less than beam width

(a)

Not less than 12.5 mm

(b)

Figure 16.14 Elevation of timber beam with GFRP sheets for shear strengthening (See Clause 16.12.3.1.)

16.12.3.2 Shear strengthening with GFRP embedded bars When the following minimum conditions for shear strengthening with GFRP bars are satisfied, the shear strength for beam and stringer grades used for the evaluation shall be assumed to be KvFRP fvu , in which KvFRP shall be taken as 2.2 and fvu shall be obtained from Table 9.13: (a) The minimum fibre volume fraction of the GFRP bars is 60%. (b) Horizontal splits in beams, if present, are closed by a mechanical device before insertion of the GFRP bars. (c) As shown in Figure 16.15, there are at least three GFRP bars at each end of the beam. (d) The diameter of the GFRP bar, db , is at least 15 mm, and the minimum diameter of a hole containing a bar is db plus 3 mm. (e) The spacing of bars along the length of the beam is h ± 25 mm. (f) The adhesive used for bonding the GFRP bars to the timber beam is compatible with the preservative treatment used on the timber and with the expected volumetric changes of the timber. (g) As shown in Figure 16.15, the GFRP bars are inclined to the beam axis at an angle of 45 ± 10° from the horizontal. (h) The tops of the inclined GFRP bars are 10 to 25 mm from the top of the beam. (i) When daps are present, the ingress of the drilled hole is 100 ± 10 mm from the edge of the dap.

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Horizontal split closed mechanically

h 45 ± 10°

Min. diameter = 15 mm

Max. h

Figure 16.15 Elevation of timber beam with GFRP bars for shear strengthening (See Clause 16.12.3.2.)

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Annex A16.1 (normative) Installation of FRP strengthening systems Note: This Annex is a mandatory part of this Code.

A16.1.1 General The selected material and its installation shall comply with the project specifications and drawings. The Plans, which include drawings, specifications, and submittals, shall comply with Clause 1.4.4.5. Qualified, experienced, and properly educated workers shall perform the strengthening work under the supervision of qualified site engineers in accordance with Clause A16.2.2. Because of the large variety of systems available for any given structural application, the installation procedure shall follow the manufacturer’s recommendations.

A16.1.2 Shipping, storage, and handling of FRP systems The shipping, storage, and handling of all fibre, resin, and FRP systems shall be performed in accordance with the manufacturer’s specifications. The fibre and resin components shall be protected from water, humidity, and excessive cold and heat throughout storage, handling, placement, and curing. The resin components shall be stored and handled in well-ventilated areas. Materials and components that are damaged, past their shelf life, or contaminated shall not be used. The Plans shall indicate the appropriate specifications. Safety measures in accordance with the applicable safety and environmental regulations shall be followed.

A16.1.3 Installation of FRP systems A16.1.3.1 General The FRP systems, including primer and putty when applicable, shall be installed on concrete surfaces approved by the Engineer and prepared in accordance with Clause A16.1.4.

A16.1.3.2 Spacing and positioning The specified FRP positioning, ply orientation, and ply stacking sequence shall be followed. Sheet and fabric materials shall be handled in a manner that maintains fibre straightness and orientation. Fabric with kinks, folds, or other forms of severe waviness shall be removed (if already installed) and discarded.

A16.1.3.3 Overlaps and multiple sheets Overlaps and multiple sheets for an FRP system may be used only when permitted by the manufacturer. Overlap splicing of FRP reinforcement shall be performed only as permitted by the Plans. Overlap length sufficient to prevent debonding in the overlapped area shall be provided. Jacket-type FRP systems used for column members shall provide appropriate overlap length at splices, joints, and termination points to prevent failure of the spliced section. Multiple sheets may be used if they are fully impregnated with the resin system and the installation of any particular sheet does not disturb the sheets already installed. When an interruption of the FRP system laying-up process occurs, interlayer surface preparation such as cleaning or light sanding can be necessary. When interlayer surface preparation is necessary, the manufacturer’s recommendations shall be followed.

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A16.1.3.4 Installation procedure The installation procedure for an FRP system shall follow the application steps recommended by the manufacturer. When needed for externally bonded FRP systems, primer and putty shall be applied to an appropriate thickness and in an appropriate sequence. They shall also be allowed to cure as specified by the FRP manufacturer before subsequent materials are applied. The primer shall be applied to all areas on the concrete surface where the FRP system is to be placed. Rough edges or trowel lines of cured putty shall be smoothed before the installation is continued. For hand-applied wet lay-up systems, the reinforcing fibre material shall be impregnated with the saturating resin in a manner recommended by the FRP manufacturer in order to obtain full saturation. The installation of the fibres of an externally bonded FRP section shall be completed within the pot life of the saturating resin. The pre-cured plate surfaces to be bonded with an adhesive resin shall be cleaned and prepared in accordance with the FRP manufacturer’s recommendations. The installation of an FRP reinforcing plate shall be completed within the pot life of the adhesive resin. The primer, putty, and saturating and adhesive resins shall be installed within their respective pot lives and in accordance with the FRP manufacturer’s recommended rate. Entrapped air under plates or sheets or between layers shall be released or rolled out before the resin sets. A protective and aesthetic coating compatible with the proposed system shall be applied in accordance with the manufacturer’s recommendations and the requirements of the Plans. For NSMR, the grooves shall be cleaned after sawing; all concrete dust, wet concrete, or laitance shall be removed; and the grooves shall be dried before bonding.

A16.1.3.5 Climatic conditions The following temperature and humidity requirements shall apply during installation of an FRP strengthening system: (a) air and concrete surface temperature: more than 10 °C; (b) concrete surface temperature above the actual dew point: more than 3 °C; and (c) atmospheric relative humidity: less than 85%. Free moisture shall not be present on the concrete surface. The surrounding temperature and relative humidity shall be continually recorded during the strengthening phase.

A16.1.4 Concrete preparation and condition for externally bonded FRP systems The concrete surfaces shall be free of particles and pieces that no longer adhere to the structure. Oil residuals and contaminants shall be removed by cleaning. The Engineer and the manufacturer’s representative shall inspect and approve the surfaces before installation proceeds. The surface shall be blast-cleaned within an appropriate period of time and/or protected before FRP installation so that no additional materials that could interfere with the bond are redeposited on the surface. The surface roughness shall be in accordance with the manufacturer’s specifications. All laitance, dust, dirt, oil, curing compounds, existing coatings, and any other matter that could interfere with the bond of the FRP shall be removed. The concrete surface to which the FRP will be applied shall be generally smooth. Small holes and voids shall be filled in accordance with the FRP manufacturer’s specifications. The concrete surfaces shall be repaired or reshaped in accordance with the original section with the material indicated in the Plans. Sections with sharp edges shall be rounded to a minimum radius of 35 mm before the FRP system is installed. The repaired surfaces shall be compatible, firmly adhere to the parent concrete, and be adequately cured before surface preparation and FRP system application. The repaired surfaces shall meet the requirements specified by the FRP system manufacturer. For bond-critical applications, the concrete substrate shall have a minimum tensile strength of 1.5 MPa, as measured by a tension test in accordance with ASTM D 4541. For contact-critical applications, the surface preparation shall ensure a continuous contact between the concrete and the FRP system.

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Canadian Highway Bridge Design Code

The depth of the depressions on the concrete surface over a bond length of 0.3 or 2.0 m shall be not more than the applicable values specified in Table A16.1.1.

Table A16.1.1 Maximum depth of depressions on the concrete surface (See Clause A16.1.4.)

Type of FRP

Maximum depth, mm, over a bond length of 0.3 m

Maximum depth, mm, over a bond length of 2.0 m

Plates ≥ 1.0 mm

4

10

Plates < 1.0 mm

2

6

Sheets

2

4

NSMR

—

—

A16.1.5 Curing conditions for FRP systems FRP systems shall be cured in accordance with the manufacturer’s recommendations. An FRP system shall be maintained in acceptable conditions for resin hardening during this period. During the cure, the temperature shall be maintained above the specified minimum; contamination and condensation on the surface shall be prevented.

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Annex A16.2 (normative) Quality control for FRP strengthening systems Note: This Annex is a mandatory part of this Code.

A16.2.1 General Before construction, the designer shall decide whether the recommended design values and quality control documentation provided by the manufacturer are acceptable. If they are determined not to be acceptable, verification tests shall be carried out on the FRP material before use. The following information shall be provided by the manufacturer: (a) the identification of the FRP system, including restrictions or limitations on its use; and (b) the results of quality control tests for verifying relevant properties, if required. The quality control and inspection programs shall be carried out in accordance with the Plans.

A16.2.2 Staff qualifications The strengthening work shall be performed by qualified personnel. The site engineer and the inspector shall also be qualified.

A16.2.3 FRP material inspection A16.2.3.1 General The FRP materials shall be inspected before, during, and after their installation. The inspection program shall cover such aspects as the presence and extent of delaminations, the cure of the installed system, adhesion, plate thickness, fibre alignment, and material properties.

A16.2.3.2 Before construction The FRP material supplier shall submit a certification and identification of all FRP materials to be used. The quantity, location, and orientation of all FRP reinforcing materials to be used, as well as information concerning shelf life, pot life, and gel time, shall be provided. Performance tests on the supplied materials shall be performed in accordance with the quality control and quality assurance test plan and shall meet the requirements specified in the Engineer’s performance specifications. Note: These tests can include measuring such parameters as the tensile strength, glass transition temperature, and adhesive shear strength.

A16.2.3.3 During construction Special care shall be taken to keep all records on the quantity of mixed resin produced each day, the date and time of mixing, the components in the mixture, the mixture proportions, the ambient temperature, the humidity, and other factors affecting the resin properties. These records shall also identify the FRP material used each day, its location on the structure, the ply count and direction of application, and all other pertinent information. Note: It is possible that visual inspection of fibre orientation and waviness will be necessary for specific FRP systems with poor orientation, which implies misalignment of the entire system from the angles specified in the drawings.

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A16.2.3.4 On completion of the project On completion of the project, a record of all final inspection and test results related to the FRP materials shall be retained and shall include delamination and repair, on-site bond tests, anomalies and correction reports, and mechanical and physical test results from the designated laboratories. Samples of the cured FRP materials shall be retained by the Engineer. An inspection of the FRP repair system shall be conducted after the full cure. Delaminations or other anomalies that are detected shall be evaluated by considering their size and number relative to the overall application area, as well as their location with respect to structural load transfer. The inspection methods may include acoustic sounding (hammer sounding), ultrasonics, and thermography, and shall be capable of detecting delaminations of 1500 mm2 or greater. Approved methods for repairing FRP materials with delaminations may be used depending on the size and number of delaminations and their locations. Cutting away the affected sheet and applying an overlapping sheet patch of equivalent plies may be used in cases where delaminations are larger than 1500 mm2 or exceed 5% of the total laminate area. The sheet shall be reinspected following the repairs and the resulting delamination map or scan shall be compared with that of the initial inspection to verify that the repairs were properly carried out. In rehabilitation of concrete structures, tension bond testing of cored samples shall be conducted for FRP sheet systems. Tension bond strength values less than 1.5 MPa shall be considered unacceptable.

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Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Section 17 — Aluminum Structures 17.1 17.2 17.3 17.3.1 17.3.2 17.4 17.4.1 17.4.2 17.4.3 17.4.4 17.4.5 17.4.6 17.5 17.5.1 17.5.2 17.5.3 17.5.4 17.5.5 17.5.6 17.5.7 17.5.8 17.5.9 17.6 17.6.1 17.6.2 17.7 17.7.1 17.7.2 17.7.3 17.7.4 17.8 17.8.1 17.8.2 17.8.3 17.8.4 17.9 17.9.1 17.9.2 17.10 17.10.1 17.10.2 17.10.3 17.10.4 17.11 17.11.1 17.11.2 17.11.3 17.12 17.12.1 17.12.2 17.12.3

Scope 738 Definitions 738 Abbreviations and symbols 740 Abbreviations 740 Symbols 740 Materials 745 General 745 Mechanical strengths 746 Physical properties 747 Bolts 747 Welding electrodes 747 Identification 747 Design theory and assumptions 748 General 748 Ultimate limit states (ULS) 748 Serviceability limit states (SLS) 748 Fatigue limit state 748 Fracture control 748 Seismic requirements 748 Resistance factors 748 Analysis 748 Design lengths of members 749 Durability 749 Corrosion protection 749 Detailing for durability 749 Design details 750 General 750 Minimum nominal thickness 750 Camber 750 Welded attachments 750 Cross-sectional areas, effective section, and effective strength 751 General 751 Cross-sectional areas 751 Effective section 751 Effective strength and overall buckling 752 Local buckling 753 Flat elements 753 Curved elements 757 Tension members 758 Limiting slenderness for tension members 758 Shear lag effect 758 Axial tensile resistance 760 Pin-connected tension members 760 Compression members 760 Limiting slenderness for compression members 760 Buckling 760 Members in axial compression 762 Flexural members 765 Classification of members in bending 765 Moment resistance of members not subject to lateral torsional buckling 765 Moment resistance of members subject to lateral torsional buckling 766

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17.12.4 17.13 17.13.1 17.13.2 17.13.3 17.13.4 17.14 17.14.1 17.14.2 17.15 17.15.1 17.15.2 17.15.3 17.15.4 17.16 17.16.1 17.16.2 17.16.3 17.16.4 17.16.5 17.16.6 17.16.7 17.17 17.17.1 17.17.2 17.17.3 17.18 17.18.1 17.18.2 17.18.3 17.18.4 17.18.5 17.19 17.19.1 17.19.2 17.19.3 17.19.4 17.19.5 17.19.6 17.19.7 17.19.8 17.19.9 17.20 17.20.1 17.20.2 17.20.3 17.20.4 17.21 17.21.1 17.21.2 17.22 17.22.1 17.22.2 17.22.3

736

Webs in shear — Flat elements 768 Members in torsion 771 General 771 Hollow sections 771 Members of solid compact cross-section 772 Members of open cross-section 772 Members with combined axial force and bending moment 772 Axial tension and bending 772 Axial compression and bending 773 Built-up compression members 775 Spacing of connectors 775 Multiple-bar members with discrete shear connectors 775 Double angle struts 776 Lattice columns and beam-columns 776 Composite beams and girders 777 General 777 Concrete slab 777 Proportioning 778 Effects of creep and shrinkage 778 Control of permanent deflections 778 Resistance of composite section 778 Shear connectors 781 Trusses 782 General 782 Built-up members 782 Bracing 782 Arches 783 General 783 Width-to-thickness ratios 783 Longitudinal web stiffeners 783 Axial compression and bending 784 Arch ties 784 Decks 784 General 784 Effective width of deck 784 Superposition of local and global effects 784 Longitudinal flexure 784 Transverse flexure 784 Decks in longitudinal compression 784 In-plane moment in decks 785 In-plane shear in decks 786 Wearing surface 786 Structural fatigue 787 General 787 Live-load-induced fatigue 787 Distortion-induced fatigue 790 Bridge decks 798 Fracture control 798 General 798 Identification 798 Splices and connections 798 General 798 Bolted connections 799 Welded connections 803

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© Canadian Standards Association

17.22.4 17.23 17.24 17.24.1 17.24.2 17.25 17.25.1 17.25.2 17.25.3 17.25.4 17.25.5 17.25.6 17.25.7 17.25.8 17.25.9

Supplement No. 2 to CAN/CSA-S6-06, Canadian Highway Bridge Design Code

Gusset plate connections 809 Anchors 809 Pins, rollers, and rockers 809 Bearing resistance 809 Pins 810 Construction requirements 810 Submissions 810 Materials 811 Fabrication 811 Welded construction 813 Bolted construction 814 Tolerances 816 Quality control 817 Transportation and delivery 818 Erection 818

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Section 17 Aluminum structures 17.1 Scope This Section specifies requirements for the design, fabrication, and erection of aluminum highway and pedestrian bridges.

17.2 Definitions The following definitions apply in this Section: Actual buckling stress, Fc — the compressive stress that causes buckling. Brittle fracture — a type of fracture in the material or structural member that cracks suddenly without prior plastic deformation. Buckling load — the load at which a member or element reaches a condition of instability. Camber — the built-in deviation of a bridge member from straight, when viewed in elevation. Characteristic resistance, Rk — the maximum force, moment, or torque that a component can be assumed to be capable of sustaining. Coating — an Approved protective system for aluminum, e.g., galvanizing, metallizing, a paint system, or coal tar epoxy. Composite beam or girder — a beam or girder structurally connected to a bridge deck so that the beam and deck respond to loads as a unit. Critical net area — the net cross-sectional area with the least tensile or tensile-shear resistance. Detail category — a category that establishes the level of stress range permitted in accordance with the classification of the detail and the number of design stress cycles. Effective section — a section in which elements, because of welding or local buckling, are reduced to their effective thicknesses. Effective strength, Fm — the reduced strength of an element, at the ultimate limit state, to account for the influence of local buckling or welding. Elastic buckling stress, Fe — the theoretical stress that initiates elastic buckling. Element — any flat or curved component of a section, such as the web of an I-beam. Erection diagrams — drawings that show the layout and dimensions of an aluminum structure and from which shop details are made. They also correlate the fabricator’s piece marks with locations on the structure. Factored compressive, tensile resistance, Cr , Tr — the product of the characteristic resistance and the resistance factor. Factored load — the product of the specified load and the load factor.

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Fatigue — the damage in the material due to initiation of microscopic cracks and propagation of such cracks into macroscopic cracks caused by the repeated application of load. Fatigue limit — the level of stress range below which no fatigue damage is assumed to occur. Flexure torsional buckling — for a member with an open cross-section symmetrical about one axis only, failure by flexure about the axis of symmetry combined with torsion. Flush — weld reinforcement not exceeding 1 mm in height that has a smooth, gradual transition with the surrounding plate (and involving grinding where necessary). Fracture-critical members — members, including attachments, in a single load path structure that are subject to tensile stress and the failure of which can lead to collapse of the structure. Fully heat-treated tempers — those tempers that are thermally heat-treated and artificially aged (T5 and T6). Gauge — the distance between successive holes, measured at right angles to the direction of the force in the member. Groove weld — a weld used to make an edge-to-edge joint between two pieces. Heat-affected zone (HAZ) — the zone of reduced strength in the metal adjacent to a weld. Heat-treated alloys — those alloys for which mechanical properties are modified by their response to heat treatment. Lateral torsional buckling — the buckling of a member involving lateral deflection and twisting. Limit state — a condition of a structure in which the design function is no longer fulfilled. Serviceability limit state — a condition represented by unacceptable deformation or vibrations. Ultimate limit state — a condition represented by fracture, collapse, overturning, sliding, or uncontrolled deformation. Limiting stress, Fo — the compressive stress that limits the capacity of a column or beam (yield, local buckling strength, or postbuckling strength). Local buckling — the buckling of an element of a member’s cross section (as distinct from the buckling of the member as a whole). Normalized buckling stress, F — the value of Fc /Fo . Normalized slenderness, l — the value of

Fo / Fe .

Notch toughness — the ability of aluminum to absorb tensile strain energy in the presence of a notch. Post-buckling resistance — the ability of elements to resist additional load after initial elastic buckling. Primary tension members — members or portions of members, including attachments (but not fracture-critical members or secondary components) that are subject to tensile stress. Prying action — an additional tensile force introduced into fasteners as a result of deformation of the parts that they connect. Resistance factor,  — a factor applied to the characteristic resistance to account for variations in material properties, product dimensions, fabrication tolerances, and assembly procedures, and to account for the imprecision of the predictor itself.

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Single load path structure — a structure in which failure of a single structural component could lead to a total collapse. Slenderness ratio,  — the effective length of a member divided by the radius of gyration, both with respect to the same axis, or the effective width of an element divided by its thickness. Slip-critical connection — a connection where slippage cannot be tolerated, including connections subject to fatigue or to frequent load reversal or where the resulting deflections are unacceptable. Smooth — a profile of weld reinforcement where any uneven surface has been ground away and the remaining metal profile merges gradually with the surrounding plate. In order to be regarded as smooth, weld reinforcements that remain after grinding are limited to 2 mm for part thicknesses of 50 mm and less and 3 mm for part thicknesses greater than 50 mm. Snug-tight — the tightness of a bolt that is attained after a few impacts of an impact wrench or the full effort of a person using a spud wrench. Specified load (service load) — a load defined in the appropriate standard or as determined by the use of the structure. Stress range — the algebraic difference between the maximum and the minimum stresses caused by fatigue loading, where tensile stress has the opposite sign to compressive stress. Web crippling — the local failure of a web plate in the immediate vicinity of a concentrated load or reaction. Weld throat — the shortest distance through a fillet, groove, flare groove, or partial penetration butt weld. Work-hardened alloys — those alloys for which the mechanical properties are modified by work hardening.

17.3 Abbreviations and symbols 17.3.1 Abbreviations The following abbreviations apply in this Section: CJP CL-W FLS HAZ PJP SLS ULS

— complete joint penetration — specified live loading in accordance with Section 3 — fatigue limit state — Heat-affected zone — partial joint penetration — serviceability limit state — ultimate limit state

17.3.2 Symbols A

= area, mm2

A’

= area enclosed by the median line of walls, mm2

Aa

= area of aluminum section, mm2

Ab

= cross-sectional area of a bolt, based on nominal diameter, mm2

Ae

= effective net area, mm2; effective area of the plate cross-section of a deck, allowing for local buckling and HAZ softening due to longitudinal welds, mm2

Af

= total area of the non-connected flanges, mm2

Ag

= gross cross-sectional area, mm2

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Am

= effective area calculated using effective thickness at welds, mm2

An

= critical net area, mm2; minimum cross-sectional area subjected to shear, allowing for holes (Clause 17.22.4), mm2

Ane

= effective net cross-sectional area (equal to sum of the critical net areas), mm2

A’ne

= reduced effective net area of tension members accounting for shear lag effects, mm2

Ar

= area of reinforcing steel within the effective width of a concrete slab, mm2

Aw

= cross-sectional area of the heat affected zone, mm2

ADDTf = single lane average daily truck traffic for fatigue a

= web length, mm; panel length between circumferential stiffeners in a curved panel, mm; length between transverse stiffeners, mm; larger panel dimension of stiffened web, mm; depth of compression block in a concrete slab, mm; least dimension across the section for solid compact bars in torsion, mm; distance from centre-to-centre of the interconnections, mm

Be

= effective width of concrete slab, mm

Bhaz

= extent of the heat affected zone (HAZ), mm

Br

= factored bearing resistance, N

b

= element width, mm; arc length of a panel between longitudinal stiffeners, mm; smaller panel dimension of a stiffened web, mm; element dimension in the direction of the stiffeners (Clause 17.19.8), mm

bn

= net length of a segment normal to the force, mm

Ca

= factored compressive force in aluminum of composite beam when the plastic neutral axis is in the aluminum section, N

Cc =

factored compressive resistance of concrete, N

Ce

= elastic lateral buckling load, N

Cf

= applied compressive force due to the factored loads, N

CL

= factor used in Clause 17.20.2.2.1

Cr =

factored compressive resistance, N; factored compressive resistance of reinforcing steel, N

Cry

= factored resistance for failure about the weak axis, N

Cw

= warping constant, mm6

c

= distance from the neutral axis of the gross section to the extreme fibre, mm; lip width, mm; elastic support from orthotropic deck plate, N/mm2; distance from the centroid of a bolt group to the centre of rotation of the group under the action of an eccentric load, mm

D

= size of fillet weld, mm

d

= diameter of bolt, mm; member depth, mm; face width of a built-up section, mm

dc

= depth of compression portion of web in flexure, mm

di

= distance from the i th bolt to the centre of rotation; mm, distance from the centre of rotation to the midpoints of the weld elements in an eccentrically loaded fillet weld pattern, mm

dm

= distance from centre of rotation to the farthest bolt in an eccentrically loaded bolt group, mm; distance from the centre of rotation to the farthest point of the weld in an eccentrically loaded fillet weld pattern, mm

do =

hole diameter, mm

d’s

= distance from extreme compressive fibre to centroid of reinforcing steel in a concrete slab, mm

E

= modulus of elasticity, MPa

Ea

= modulus of elasticity of aluminum, MPa

Ec

= modulus of elasticity of concrete, MPa

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e

= eccentricity, mm; distance from the center of bearing to the end of the beam (Clause 17.12.4.6), mm; perpendicular distance from the hole centre in a bolted connection to the end edge in the direction of loading, mm; eccentricity of the applied load from the centroid of a bolt group, mm

ea

= lever arm between the factored tensile resistance and the factored compressive resistance of the aluminum, mm

ec

= lever arm between the factored tensile resistance and the factored compressive resistance of the concrete, mm

er

= lever arm between the factored tensile resistance and the factored compressive resistance of the reinforcing steel, mm

FF Fbc Fc Fe Fm Fo Fsc Fsr Fsrt Fsu Fsy Fu Fwu Fwy Fy f

= normalized buckling stress for elements or members

fbf

= factored longitudinal compressive stress in web due to the overall bending moment, MPa; factored longitudinal compressive stress at the bearing point due to the factored moment (Clause 17.12.4.6), MPa

= local web buckling stress due to compression caused by bending, MPa = buckling stress, MPa; local buckling stress of a flat element, MPa = elastic buckling stress, MPa = effective strength, MPa = limiting stress, MPa = buckling stress in shear, MPa = fatigue stress range resistance, MPa = constant amplitude threshold stress range, MPa = shear ultimate strength, MPa = shear yield strength, MPa = specified minimum tensile ultimate strength, MPa = ultimate strength in the heat-affected zone, MPa = yield strength in the heat-affected zone, MPa = specified minimum tensile yield strength, MPa = minimum permanent tension stress, MPa; un-factored compressive stress at toe of flange in arches, MPa

f ‘c

= specified compressive strength of concrete, MPa

fsf

= factored applied shear stress, MPa

fsr

= calculated fatigue stress range at the detail due to passage of the CL-W Truck, MPa

fy

= specified minimum yield strength of reinforcing steel, MPa

f1

= maximum compressive stress (negative), MPa

f2

= stress at the other edge, positive when the stress is tensile, MPa

G

= shear modulus of elasticity, MPa

g

= transverse spacing between fastener gauge lines, mm; transverse spacing of two holes, mm

ge

= transverse edge distance of a fastener, mm

H

= total length of the median line of a weld in an eccentrically loaded fillet weld pattern, mm

h

= web depth, mm; width of element in the direction of the shear force (Clause 17.19.8), mm

I

= moment of inertia per unit width of the gross stiffened section, mm4/mm

Ieff

= moment of inertia of the effective cross-section for in-plane bending of stiffened deck, mm4

Im

= moment of inertia per unit width of the supported medium, mm4/mm

Ip

= polar moment of inertia of flange and stiffener about the supported edge, mm4

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Is

= moment of inertia of the stiffener about the inside surface of the flange to which it is attached, mm4; moment of inertia of the longitudinal stiffener about the web of the beam (Clause 17.18.3), mm4

Iy

= moment of inertia about the weak axis of the member, mm4

J

= St. Venant torsional constant, mm4

K

= effective length factor

k

= spring constant for the restraint provided by the connection between flange and web; a factor related to the direction of the force applied to a fillet weld

L

= unbraced length of the member, mm; length of the connection in the direction of loading, measured as the distance between the first and the last bolt in a bolted connection and as the overall length of weld pattern in a welded connection, mm; length of roller or rocker, mm; actual length of fillet weld, mm

Lm

= effective length of a fillet weld, mm

Ln

= net length of a segment parallel to the force, mm

Md

= bending moment in beam or girder at SLS due to dead load, N•mm

Mf

= factored bending moment in a member or component at ULS, N•mm; factored moment resistance from unrestrained member (Clause 17.14.1.3), N•mm; maximum moment due to the factored lateral load (Clause 17.14.2.1), N•mm

Mfmax = maximum factored end moment (Clause 17.14.2.1), N•mm Mfx

= moment in the member due to the factored lateral load about the strong axis, N•mm

Mfy

= moment in the member due to the factored lateral load about the weak axis, N•mm

ML

= bending moment in beam or girder at SLS due to live load, N•mm

Mp

= fully plastic moment, N•mm

Mr

= factored moment resistance of a member or component, N•mm

Msd

= bending moment in beam or girder at SLS due to superimposed dead load, N•mm

My

= moment at first yield, N•mm

M1, M2 = applied moments due to the factored loads (Clause 17.14.2.1), N•mm m

= local buckling factor; number of shear planes in a bolted joint (equal to one for bolts in single shear and two for bolts in double shear); fatigue life constant

N

= number of chords in a built-up section

Nc =

specified number of design stress cycles

Ncr

= elastic orthotropic buckling load based on the gross cross-section, N

Nd

= number of design stress cycles experienced for each passage of the design truck

n

= number of bolts; bearing length (Clause 17.12.4.6), mm; modular ratio = Ea /Ec ; number of heat paths in a weld

ncr

= factored compressive resistance per unit length of a fillet welded plate, N/mm

nsr

= factored shear resistance per unit length of a fillet welded plate, N/mm

ntr

= factored tensile resistance per unit length of a fillet welded plate, N/mm

nx

= shear force per unit length of a fillet welded plate, N/mm

Pf

= factored load, N

Pr

= factored resistance, N

p

= pitch (longitudinal spacing) between bolts, mm; pitch of threads, mm

Qf

= factored torsional moment in a bolted joint at ULS, N•mm; factored applied torsional load, N•mm

Qr

= factored torsional resistance in a bolted joint, N•mm; factored torsional resistance of sections, N•mm

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R

= radius of curvature, mm; radius of the circle measured to the centre of the holes (Clause 17.22.2.8), mm; interior bent radius (Clause 17.12.4.6), mm

Rf

= highest factored force on a bolt in an eccentrically loaded bolt group, N

Rk = Rr

characteristic resistance of a fastener, N = factored resistance of a bolt, N

R1, R2 = radius of roller or rocker and of groove of supporting plate, respectively, mm r

= radius of gyration for the axis of bending, mm; radius of gyration of the total cross-section (Clause 17.15.4), mm; overall radius of gyration of the cross-section of a lattice section (Clause 17.15.4), mm; radius of gyration of the gross stiffened section (Clause 17.19.6), mm

r’

= radius of gyration of the total section for the built-up axis, mm

rv

= minimum radius of gyration, mm

rx

= radius of gyration of the gross cross-section about its strong axis, mm

ry

= radius of gyration of the gross cross-section about its weak axis, mm

r’

= polar radius of gyration about the shear centre

S

= elastic section modulus of the gross aluminum section, mm3

Sc

= section modulus of the extreme fibre in compression, mm3

Sm

= effective section modulus using the effective thickness, mm3

Sn

= net elastic section modulus, mm3

Sn, S3n = elastic section modulus comprising the aluminum beam or girder and the concrete slab, calculated using a modular ratio of n or 3n, respectively, mm3 St

= section modulus of the extreme fibre in tension, mm3

Sx

= section modulus of the gross section about the strong axis, mm3

Sy

= section modulus of the gross section about the weak axis, mm3

s

= spacing of fasteners along a line of connections, mm; distance between transverse stiffeners, mm; centre-to-centre distance between adjacent bolts on the circle of a bolt group (Clause 17.22.2.8), mm

T

= tension in bolts at SLS, N

Ta

= factored tensile resistance of aluminum section or component, N

Tf

= factored tensile force in a member, bolt, or component at ULS, N

Tr

= factored tensile resistance of a member, bolt, or component, N

T1

= interpass MIG weld temperature, C

t

= element thickness, mm

tb

= thickness of bottom flange, mm

tc

= thickness of concrete slab, mm

tm

= effective thickness at welds, mm

tt

= thickness of top flange, mm

tw

= throat of fillet weld, mm

t1, t2 = thickness of lap connected plates (t1 < t2), mm V

= shear force at SLS, N

Vf

= factored shear force at ULS, N

Vr

= factored shear resistance, N

Vs

= slip resistance in a bolted joint at SLS, N

vf

= maximum force per unit length, N/mm

vk

= characteristic ultimate shear resistance per unit length of the boundaries or seams in a stiffened web (riveted or bonded), N/mm

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vr

= factored ultimate shear resistance per unit length at the boundaries, N/mm

W

= gross weight of the CL-W Truck, kN

w

= web thickness, mm

X

= distance perpendicular to axis of member from the fastener plane to the centroid of the portion of the area of the cross-section under consideration, mm

xi

= x-coordinate of the i th bolt relative to the centroid of the bolt group, mm

xo

= distance from the centroid to the shear centre, mm

y

= eccentricity of the connection in the fastener plane, mm; distance from the neutral axis of the gross cross-section to the centre of the weld or bolt hole, mm

yb

= distance from the centroid of an aluminum section to the bottom fibre of an aluminum beam or girder, mm

y’b

= distance from the centroid of the lower portion of an aluminum section under tension or compression to the bottom fibre of a beam or girder, mm

ybc

= distance from the plastic neutral axis of a composite section to the bottom fibre of an aluminum beam or girder, mm

yi

= y-coordinate of the i th bolt relative to the centroid of the bolt group, mm

yst

= distance from the centre of deck to the centre of the outermost stiffener, mm

yt

= distance from the centroid of an aluminum section to the top fibre of an aluminum beam or girder, mm

y’t

= distance from the centroid of the upper portion of an aluminum section under tension or compression to the top fibre of an aluminum beam or girder, mm

ytc

= distance from the plastic neutral axis of a composite section to the top fibre of an aluminum beam or girder, mm

Z

= plastic section modulus of the gross area, mm3

Zn

= net plastic section modulus, mm3

  

= coefficient of thermal expansion, /°C = fatigue life constant pertaining to detail categories (Clause 17.20.2.4) = angle made by the end edge of a bolted connection with the direction of the force, degree; acute angle between web and bearing surface (Clause 17.12.4.6), degree

 l f t

= slenderness parameter; damage equivalence factor



= Poisson’s ratio

 c f r u y

= density, kg/m3

= normalized slenderness parameter = slenderness for flexural buckling = slenderness for torsional buckling

= resistance factor for concrete determined in accordance with Section 8 = resistance factor for fasteners = resistance factor for reinforcing steel in composite construction in accordance with Section 10 = resistance factor on ultimate strength = resistance factor on yield strength

17.4 Materials 17.4.1 General Aluminum highway bridge material shall comply with ASTM B209, ASTM B211, ASTM B221, ASTM B308, ASTM B429, or ASTM B928. Alloys 5052, 5083, 5086, 6005A, 6061, 6063, or 6082 shall be used.

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For aluminum pedestrian bridges, material shall comply with (a) the requirements for aluminum highway bridges; or (b) ASTM B26 or ASTM B108. Alloys 356.0-T6, A356.0-T61, or A357.0-T61 shall be used and Clause 12.5.5.2.3 shall apply. The purchaser shall require the casting producer to report tensile yield strengths. For sand castings, the purchaser shall require that tensile ultimate and tensile yield strengths of specimens cut from castings be at least 75% of the values specified in ASTM B26. Radiographic inspection in accordance with ASTM B26 Grade C or ASTM B108 Grade C criteria is required. The number of castings to be radiographed and the lot acceptance shall be as given in Table 17.1.

Table 17.1 Radiographic inspection frequency requirements for castings (See Clause 17.4.1.)

Lot size

Number of castings to be radiographed

Number of castings to meet Grade C to pass lot

2–50

2

2

51–500

8

7

13

11

500

17.4.2 Mechanical strengths Mechanical strengths shall be as given in Table 17.2.

Table 17.2 Mechanical strengths (See Clause 17.4.2.) Strength

Wrought alloys

Cast alloys

Fu

Minimum tensile ultimate strength given in the ASTM standards listed in Clause 17.4.1

75% of the minimum tensile ultimate strength given in the ASTM standards listed in Clause 17.4.1

Fy

Minimum tensile yield strength given in the ASTM standards listed in Clause 17.4.1

75% of the minimum tensile yield strength given in the ASTM standards listed in Clause 17.4.1

Fwu

Welded tensile ultimate strength given in CSA W47.2

Fwy

Welded tensile yield strength given in CSA W47.2

Fsu

Shear ultimate strength = 0.6Fu

Fsy

Shear yield strength = 0.6Fy

Note: Mechanical strengths for commonly used products are given in Table 17.3.

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Table 17.3 Mechanical strengths for common wrought products (See Clauses 17.12.4.2, 17.22.3.1, and 17.22.3.4.2 and Table 17.2.) Thickness, mm Alloy-temper

Product

Over

5052-H32

Sheet, plate

0.40

5083-H116

Sheet, plate

5086-H116

Through

Minimum strength, MPa Fu

Fy

Fwu

Fwy

50.00

215

160

170

65

1.60

40.00

305

215

270

115

Sheet, plate

1.60

50.00

275

195

240

95

5086-H321

Sheet, plate

1.60

8.00

275

195

240

95

6005A-T61

Extrusion

—

25.00

260

240

165

90

6063-T5

Extrusion

—

12.50

150

110

115

55

6063-T6

Extrusion

—

25.00

205

170

115

55

6061-T6, -T6510, -T6511

Extrusion

All

—

260

240

165

80* 105†

6061-T6

Sheet

0.15

6.30

290

240

165

105

6061-T651

Sheet, plate

6.30

100.00

290

240

165

80* 105†

6082-T6, -T6511

Extrusion

5.00

150.00

310

260

190

110

*When welded with 4043 filler in parts thicker than 9.5 mm. †When welded with 5356 filler, or welded with 4043 filler in parts 9.5 mm or less in thickness.

17.4.3 Physical properties The following physical properties shall be used for design purpose: (a) the coefficient of thermal expansion  : 24 × 10–6 /°C; (b) the density : 2700 kg/m3; (c) the modulus of elasticity E: 70 000 MPa; (d) the shear modulus of elasticity G: 26 000 MPa; and (e) Poisson’s ratio  : 0.33.

17.4.4 Bolts Bolts and nuts shall be as follows: (a) Aluminum bolts shall comply with ASTM F468. Aluminum nuts shall comply with ASTM F467. (b) Steel bolts shall comply with ASTM A325M. Steel nuts shall comply with ASTM A563M. Steel bolts and nuts shall be zinc-coated. (c) Stainless steel bolts shall comply with ASTM F593 Group 1 or 2. Stainless steel nuts shall comply with ASTM F594 Group 1 or 2.

17.4.5 Welding electrodes Welding electrodes shall comply with AWS A5.10/A5.10M and be certified by the Canadian Welding Bureau.

17.4.6 Identification The specifications of the materials and products used, including alloy and temper, shall be identified by mill test certificates or manufacturer’s certificates satisfactorily correlated to the materials or products to which they pertain.

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17.5 Design theory and assumptions 17.5.1 General Structural members and components shall be proportioned to satisfy the requirements for the ultimate, serviceability, and fatigue limit states.

17.5.2 Ultimate limit states (ULS) The factored resistances specified in Section 17 shall be equal to or greater than the effect of factored loads specified in Section 3 for all relevant ULS considerations, including strength, rupture, bending, buckling, lateral torsional bucking, sliding, overturning, and uplift.

17.5.3 Serviceability limit states (SLS) 17.5.3.1 General SLS include deflection, yielding, slipping of bolted joints, and vibration.

17.5.3.2 Deflection The requirements of Clause 3.4.4 shall apply.

17.5.3.3 Yielding Members shall be proportioned so that general yielding does not occur. Limited local yielding may be used.

17.5.3.4 Slipping of bolted joints The requirements of Clause 17.22 shall apply.

17.5.3.5 Vibration The requirements of Section 3 shall apply.

17.5.4 Fatigue limit state The requirements of Clause 17.20 shall apply.

17.5.5 Fracture control The requirements of Clause 17.21 shall apply.

17.5.6 Seismic requirements The requirements of Clause 4.13 shall apply.

17.5.7 Resistance factors Resistance factors shall be as follows: (a) yield strength: y = 0.90; (b) ultimate strength, groove welds: u = 0.75; (c) fasteners, fillet welds: f = 0.67; (d) for materials working in composite action with aluminum, applicable resistance factors found in this Code shall be used.

17.5.8 Analysis Unless other methods are Approved, the methods specified in this Section and Section 5 shall be used for aluminum bridge design and analysis. Members shall be designed for the effect of any eccentricity arising from their connections.

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17.5.9 Design lengths of members 17.5.9.1 Span lengths Span lengths shall be taken as the distance between centres of bearings or other points of support.

17.5.9.2 Compression members 17.5.9.2.1 General The design of a compression member shall be based on its effective length KL. The unbraced length L shall be taken as the length of the compression member measured centre-to-centre of restraints. The unbraced length may differ for different cross-sectional axes of a member. For the bottom level of a multi-level bent or for a single-level bent, L, shall be measured from the top of the base plate. The effective length factor, K, shall be as specified in Clauses 17.5.9.2.2, 17.5.9.2.3, or 17.5.9.2.4, depending on the potential failure modes and whether failure is by buckling or in-plane bending.

17.5.9.2.2 Failure modes involving in-plane bending The effective length shall be taken as the actual unbraced length, i.e., K = 1.0, for beam-columns that would fail by in-plane bending, but only if, when applicable, the sway effects have been included in the analysis of the structure to determine the end moments and forces acting on the beam-columns.

17.5.9.2.3 Failure modes involving buckling The effective length for axially loaded columns that would fail by buckling and for beam-columns that would fail by out-of-plane lateral torsional buckling shall be based on the rotational and translational restraint afforded at the ends of the unbraced length.

17.5.9.2.4 Compression members in trusses The effective length for members that would fail by in-plane bending shall be taken as the actual unbraced length, i.e., K = 1.0. The effective length for members that would fail by buckling shall be based on the rotational and translational restraint afforded at the ends of the unbraced length. For half-through or pony-truss spans, the critical buckling load of the compression chord shall be determined in accordance with Clause 17.17.3.6.

17.6 Durability 17.6.1 Corrosion protection Aluminum in contact with dissimilar materials shall be protected against corrosion as follows: (a) Aluminum in contact with concrete or masonry, wood, or metals other than steel shall be coated with an Approved coating system, or an inert separator shall be provided between the aluminum and these materials. (b) Steel in contact with aluminum shall be coated with an Approved coating system or zinc-coated. No coating is required for 300 series stainless steel in contact with aluminum. (c) Aluminum shall not be placed where runoff from other metals might come in contact with the aluminum.

17.6.2 Detailing for durability 17.6.2.1 Drip bars Drip bars shall be secured to the bottom flanges of plate girders near expansion joints.

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17.6.2.2 Interior bracing Interior bracing shall be detailed to allow access for inspection and maintenance over the full length of the bridge.

17.6.2.3 Angles and tees Angles and tees exposed to the environment shall be placed with their vertical legs or webs extending downward wherever practical.

17.6.2.4 End floor beams and end diaphragms End floor beams and end diaphragms under expansion joints shall be arranged to permit coating and future maintenance of surfaces that are exposed to surface runoff. The end diaphragms of box girders shall be detailed to prevent ingress of water into the boxes.

17.6.2.5 Pockets and depressions Pockets and depressions that could retain water shall be avoided, provided with effective drainage, or filled with water-repellent material.

17.7 Design details 17.7.1 General Members and connections shall be detailed to minimize their susceptibility to fatigue and brittle fracture.

17.7.2 Minimum nominal thickness The nominal thickness of aluminum plates or components shall be not less than 5 mm unless a smaller thickness can be Approved through a bridge-specific evaluation of fabrication, shipping, and erection procedures.

17.7.3 Camber 17.7.3.1 Design Girders with spans 25 m long or longer shall be cambered to compensate at least for dead load deflections and to suit the bridge profile grade. For composite beams with concrete, an allowance shall also be made for the effects of creep and shrinkage of the concrete. The Plans shall show (a) the deflection of the girders due to the dead load of the aluminum members alone; and (b) the deflection due to the full dead load, including that of the aluminum structure, slab, barriers, sidewalks, and wearing surface. For spans shorter than 25 m, the deflections and the profile of the concrete deck slab over the beams may be accommodated by increasing the slab thickness over the beams in lieu of providing a camber, if specified on the Plans.

17.7.3.2 Fabrication Shop drawings shall show the camber diagram. The camber diagram shall include compensation for the deflection due to full dead load, an allowance for fabrication and welding distortion, and an allowance (if applicable) for the vertical alignment of the bridge.

17.7.4 Welded attachments All attachments to primary tension and fracture-critical members, including transverse and longitudinal stiffeners, shall be connected by continuous welds. Longitudinal stiffeners shall be spliced by complete joint penetration groove welds.

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17.8 Cross-sectional areas, effective section, and effective strength 17.8.1 General To account for the drilling of holes, deductions shall be made from the gross cross-section to give a net section in accordance with Clause 17.8.2.2. Effective section to account for welding shall be determined by using effective thickness in accordance with Clause 17.8.3.2. Strength reduction due to local buckling shall be represented by a reduction in the effective strength.

17.8.2 Cross-sectional areas 17.8.2.1 Gross area The gross cross-sectional area, Ag , shall be the sum of the products of the thickness times the gross width of each element in the cross-section, measured perpendicular to the longitudinal axis of the member.

17.8.2.2 Effective net area The effective net cross-sectional area, Ane , shall be the sum of the critical net areas, An , of each segment along a potential path of minimum resistance. Such potential paths of minimum resistance can extend from one side of the member to the other or can define a block of material within the member that can tear out, i.e., block tear-out. The critical net areas shall be calculated as: (a) An = bnt for any segment normal to the force (i.e., in direct tension); (b) An = 0.6Lnt for any segment parallel to the force (i.e., in shear); and (c) An = bnt + s2t/4g for any segment inclined to the force. where bn = net length of a segment normal to the force, mm t

= element thickness, mm

Ln = net length of a segment parallel to the force, mm s

= spacing of successive holes in the direction of the force, mm

g

= transverse spacing of two holes, mm

The net width, bn , shall be taken as gross width minus the sum of hole diameters (do) in the gross width. The net length, Ln , shall be taken as gross length minus the sum of hole diameters in the gross length. Deductions for fastener holes shall be made using a diameter 2 mm greater than the hole diameter specified in Clause 17.22.2.10.2.

17.8.2.3 Effective area at welded connections The effective cross-sectional area of longitudinally welded sections, Am , shall be determined by using the effective thickness from Clause 17.8.3.2.

17.8.3 Effective section 17.8.3.1 General The geometric properties of the effective section shall be determined using the effective thicknesses of the elements specified in Clause 17.8.3.2.

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17.8.3.2 Effective thickness at welds 17.8.3.2.1 Effective thickness for plastic sections Where only parts of the cross-section are influenced by welding, as with longitudinal welds, the effective thickness, tm , of the metal in heat-affected zone, shall be taken as

⎛ Fwy ⎞ tm = t ⎜ ⎟ ≤t ⎝ Fy ⎠ The plastic section modulus of the effective section shall be used for determining the plastic moment resistance.

17.8.3.2.2 Effective thickness for elastic sections The effective thickness, tm , used in calculating the elastic section modulus shall be determined from

⎛ Fwy ⎞ ⎛ c ⎞ tm = t ⎜ ⎟⎜ ⎟ ≤t ⎝ Fy ⎠ ⎝ y ⎠ where t = original thickness, mm Fwy = yield strength in the heat-affected zone, mm Fy

= specified minimum tensile yield strength, MPa

c

= distance from the neutral axis of the gross cross-section to the extreme fibre, mm

y

= distance from the neutral axis of the gross section to the centre of the weld, mm

The elastic section modulus of the effective section shall be used for determining the moment resistance at first yield, except that if local buckling occurs in a welded element, Clause 17.8.4.3 shall apply.

17.8.3.2.3 Deflections The gross cross-section of welded members shall be used for the calculation of deflections.

17.8.4 Effective strength and overall buckling 17.8.4.1 General Where welding, or local buckling with post-buckling strength, influences the flexural buckling of columns or lateral buckling of beams, the resistance shall be established by using the effective strength, Fm , given in Clauses 17.8.4.2 and 17.8.4.3.

17.8.4.2 Influence of welding For members with longitudinal welds, the effective strength, Fm , shall be taken as

⎛A ⎞ Fm = Fy − (Fy − Fwy ) ⎜ w ⎟ ⎝ Ag ⎠ where Aw = cross-section area of the heat-affected zone, mm2 Ag = gross cross-sectional area, mm2 This value of effective strength shall be used as the limiting stress Fo , in Clauses 17.11.2.2(g) and 17.11.3.1, in conjunction with the gross cross-sectional area, Ag , when determining the resistance to overall buckling.

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17.8.4.3 Influence of local buckling 17.8.4.3.1 Flat elements with both longitudinal edges supported For flat elements supported on both longitudinal edges, subjected to compressive stress that can cause local buckling, the effective strength, Fm , of the element shall be taken as

Fm = F Fy where

F = normalized buckling stress, from Clause 17.11.2.3 The value of Fm shall be used as the limiting stress, Fo , in Clauses 17.11.2.2(c) and 17.11.3.1, in conjunction with the gross cross-sectional area, Ag , when determining the resistance to overall buckling.

17.8.4.3.2 Flat elements with one longitudinal edge supported Angle sections and outstanding elements supported along only one longitudinal edge shall not be considered to possess post-buckling strength, and elastic buckling shall be deemed to lead to member failure.

17.8.4.3.3 Deflections If the local buckling at the SLS is elastic, the gross cross-sectional properties may be used for calculating deflections.

17.9 Local buckling 17.9.1 Flat elements 17.9.1.1 Buckling stress The buckling stress, Fc , of a flat element subjected to compressive stress shall be obtained using a slenderness, , taken as

l=

mb t

where m = the local buckling factor given in Clauses 17.9.1.2 and 17.9.1.3 The value of  shall be used to determine the normalized slenderness, l (see Clause 17.11.2.1). Clause 17.11.2.3 shall then be used to determine the normalized buckling stress and hence the actual initial buckling stress, Fc , taken as

Fc = F Fy The element width, b, shall be measured as follows [see Figure 17.1(a)]: (a) For sections of uniform thickness, e.g., shapes formed from sheet, b shall be measured from the intersections of the centre lines of adjacent elements, ignoring any corner radii. (b) For extruded sections with root fillets at the junctions, b shall be the distance from the tangent points of the root radii.

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b

b

b

a) Measurement of width b t

b

w/2

b

a

w

w

a

t

w

a

t

Axis of bending

b

b) Flanges supported on two long edges t/2

b t

a

w

t

b

w

a

c) Flanges supported on one long edge

Figure 17.1 Basic geometric parameters for local buckling (See Clauses 17.9.1.1, 17.9.1.2.3, and 17.9.1.3.2.)

17.9.1.2 Flat elements supported on both longitudinal edges 17.9.1.2.1 General

The various slenderness values, , of this Clause with the yield strength, Fy , shall be used to determine the normalized slenderness, l , in Clause 17.11.2.1, to give the normalized buckling stress, F , from Clause 17.11.2.3. The local buckling stress shall then be Fc = F Fy , which shall be used as Fo when determining the overall buckling resistance of non-compact columns and beams.

17.9.1.2.2 Elements in bending in their own plane

For a linear variation in stress across an element whose long edges are simply supported,  shall be taken as

l=

mb t

where

m = 1.15 +

754

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1.3 , when f2 /f1 < −1 f2 1− f1 where f1 = maximum compressive stress, negative, MPa f2 = stress at the other edge, positive when the stress is tensile, MPa

Note: A range of cases is illustrated in Figure C17.3 of the Commentary.

17.9.1.2.3 Elements in uniform compression Where an element of width b, subjected to nominally uniform compressive stress, is connected along both edges to elements of width a that are also supported along their edges [see Figure 17.1(b) or Figure C17.4 of the Commentary],  shall be taken as

l=

mb t

where for members in axial compression, when b/t  a/w,

m = 1.25 +

0.4 (a /w ) ≤ 1.65 (b /t )

for elements in bending, such as decking profiles, when a/w  2.5b/t,

m = 1.25 +

0.2 (a /w ) ≤ 1.65 (b /t )

When a/w > 2.5 b/t, the web shall be checked for buckling using Clause 17.9.1.2.2.

17.9.1.3 Flat elements supported on one longitudinal edge only 17.9.1.3.1 Elements in bending in their own plane For a linear variation of longitudinal stress across an element that has one edge simply supported and the other edge free, buckling is in the torsional mode and the slenderness, , shall be taken as

l=

mb t

where (a) when the maximum compressive stress is at the free edge (see Figure C17.5 of the Commentary),

m = 2.5 3 +

f2 f1

When f2/f1 < –3, buckling does not occur. (b) when the maximum compressive stress is at the supported edge (see Figure C17.5 of the Commentary), for f2/f1 > –0.28,

m = 2.5 1+ 3

f2 f1

The element width, b, shall be measured, as described in Clause 17.9.1.1. When f2/f1 < –0.28, Clause 17.9.1.2.2 shall be used.

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17.9.1.3.2 Elements in uniform compression

The slenderness, , such as for flanges of channels, Z-sections, and I-sections subjected to uniform compressive stress due to axial force or bending (see Figure 17.1(c) or Figure C17.6 of the Commentary) shall be taken as

l=

mb t

where

⎛ at ⎞ m = 3 + 0.6 ⎜ ≤5 ⎝ bw ⎟⎠

17.9.1.4 Elements supported on one edge with a lip on the other edge 17.9.1.4.1 General shapes For the general case of a flange element attached at one longitudinal edge to a web element with a lip at the other longitudinal edge (see Figure C17.7 of the Commentary), subjected to uniform compressive stress,  used to obtain the buckling stress shall be taken as

5

Ip

l= 1+ 5.3

J Cw k J

where Ip = polar moment of inertia of flange and stiffener about the supported edge, mm4 = St. Venant torsional constant for flange and stiffener, mm4

J

Cw = warping constant, mm6, for rotation of the flange and stiffener about the supported edge = Is b2 where Is

= moment of inertia of the stiffener about the inside surface of the flange to which it is attached; this applies to all types of stiffener, including inclined lips and bulbs, mm4

b

= flange width measured from the intersection of the median lines of the flange and web, mm

= spring constant for the restraint provided by the connection between flange and web

k

=

3w 3 for channel and Z-sections 16 (a + 0.5b )

=

1.5w 3 for I-sections 16 (a + 0.5b )

17.9.1.4.2 Shapes of uniform thickness with stiffeners 17.9.1.4.2.1 Perpendicular stiffeners

For shapes of uniform thickness, with a formed stiffener at 90° [see Figure C17.7(a) of the Commentary],  shall be taken as

l=

5b t

756

1+ 3b 1+ b + 3.7

b 3 (b /t ) 2 + 0.1 (a / b) + 0.5

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1.6b 5c or t t where l≥

b=

c b

17.9.1.4.2.2 Inclined stiffeners (45°)

For shapes of uniform thickness, with a formed stiffener at 45°,  shall be taken as

l=

l≥

1+ 3b

5b t

0.5b 3 (b /t ) 2 + 0.1 (a / b) + 0.5

1+ b + 3.7

1.6b 5c or t t

These expressions may also be used for walls with multiple stiffeners when the section is bent about the neutral axis, as shown in Figure C17.7(b) of the Commentary. In such a case, the stiffener spacing is 2a.

17.9.2 Curved elements 17.9.2.1 Axial compression The buckling stress, Fc , of a tube or curved element shall be obtained from Clause 17.11.2.3 using the limiting stress, Fo = Fy , and the appropriate value of , given by one of the following formulas: (a) for tubes:

l=4

R t

⎛ R⎞ ⎜ 1+ 0.03 t ⎟ ⎝ ⎠

(b) for curved elements (see Figure C17.8 of the Commentary):

l=

l1 ⎛l ⎞ 1+ ⎜ 1 ⎟ ⎝ l2 ⎠

4

where R = radius of curvature, mm t

= eleme nt thickness, mm

l1 =

3.3(a /t ) 1 + (a / b )2

= 1.65

when a < b

b when a ≥ b t

where a = element length between circumferential stiffeners, mm b = arc length of the element between longitudinal stiffeners, mm

2 = slenderness from Item (a)

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17.9.2.2 Radial compression The buckling stress, Fc , for a radially loaded tube, with circumferential stiffeners spaced at a distance a apart, shall be obtained from Clause 17.11.2.3 using the limiting stress, Fo = Fy , and the appropriate value of the slenderness, , taken from one of the following formulas:

(a) when a / R > 3.3 R / t , then the following shall be used: R l=6 t (b) when a / R < 3.3 R / t , then the following shall be used: l = 3.3

a t

4

R t

(c) for long curved elements supported on straight longitudinal boundaries, (i) when b/R > , then the following shall be used:

l=

6R t

(ii) when b/R < , then the following shall be used:

l=

3.3

R t

2

⎛ R⎞ ⎜⎝ 2 ⎟⎠ − 0.1 b

17.10 Tension members 17.10.1 Limiting slenderness for tension members Where the proportions of a tension member are to be limited to avoid excessive deflection under incidental lateral loads and vibrations, the following limit shall be observed:

KL f < 250 1+ r Fe where K = effective length factor (see Table 17.4) r = radius of gyration, mm f = minimum permanent tension stress, MPa

Fe =

p 2E l2

For members subjected to wind, see Clause 17.11.1.

17.10.2 Shear lag effect 17.10.2.1 General Where tension is transmitted by fasteners or welds to some but not all of the cross-sectional elements of the member, the reduced effective net area, A’ne , for the member (consisting of angles, channels, tees, zees, and I-shaped sections) shall be determined from Clauses 17.10.2.2 to 17.10.2.4.

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Shear lag effect shall not be included when the factored tensile resistance is determined by block tear-out in the connected members such as gusset plates, or block tear-out in the directly connected elements of the tension member under consideration that does not extend into the unconnected elements.

17.10.2.2 Angle connected by a single fastener at each end When an angle is connected by a single fastener at each end, the reduced effective net area, A’ne , shall be taken as effective net area of the connected leg, but not greater than (2ge – do)t where t is the angle thickness, ge is the transverse edge distance for the fastener, and do is the hole diameter.

17.10.2.3 Members connected by one transverse line of fasteners For members connected by only one transverse line of fasteners with two or more fasteners, the reduced effective net area, A’ne , shall be taken as the sum of the effective net area of each connected element.

17.10.2.4 Members connected by two or more transverse lines of fasteners For members connected by two or more transverse lines of fasteners, the reduced effective net area, Ane , shall be determined as follows:

⎛ X⎞ Ane ′ = Ane ⎜ 1 − ⎟ L⎠ ⎝ where Ane = effective net cross-sectional area (equal to the sum of the critical net areas), mm2

X

= distance perpendicular to axis of member from the fastener plane to the centroid of the portion of the area of the cross-section under consideration, mm

L

= length of the connection in the direction of loading, measured as the distance between the first and the last bolt in a bolted connection and as the overall length of weld pattern in a welded connection, mm

In lieu of the detailed calculation at the beginning of this Clause, the reduced effective net area may be as follows: (a) for I-sections connected only by the web, (i) with four or more transverse lines of fasteners: A’ne = 0.90 Ane ; (ii) with three transverse lines of fasteners: A’ne = 0.80 Ane ; or (iii) with two transverse lines of fasteners: A’ne = 0.60 Ane ; (b) for I-sections connected only at the flanges, (i) with four or more transverse lines of fasteners: A’ne = 0.90 Ane ; (ii) with three transverse lines of fasteners: A’ne = 0.80 Ane ; or (iii) with two transverse lines of fasteners: A’ne = 0.70 Ane ; (c) for channels connected by the web, (i) with four or more transverse lines of fasteners: A’ne = 0.90 Ane ; (ii) with three transverse lines of fasteners: A’ne = 0.85 Ane ; or (iii) with two transverse lines of fasteners: A’ne = 0.70 Ane ; (d) for tees connected at the flange, (i) with three or more transverse lines of fasteners: A’ne = 0.80 Ane ; or (ii) with two transverse lines of fasteners: A’ne = 0.60 Ane ; or (e) for angles connected by one leg, (i) with four or more transverse lines of fasteners: A’ne = 0.90 Ane ; (ii) with three transverse lines of fasteners: A’ne = 0.60 Ane ; or (iii) with two transverse lines of fasteners: A’ne = 0.50 Ane .

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17.10.3 Axial tensile resistance The factored axial tensile resistance of a tension member, Tr , shall be taken as the least of (a) general: y Ag Fy ; (b) with mechanical fasteners: u Ane Fu or u A’ne Fu ; (c) with transverse butt welds: u Ag Fwu; or (d) with longitudinal welds: y AmFy or y Ag Fm where Am = effective area of the welded section using Clause 17.8.3.2.1, mm2 Fm = effective strength defined in Clause 17.8.4.2, MPa

17.10.4 Pin-connected tension members In pin-connected members in tension, the net area, An , across the pin hole and normal to the axis of the member, shall be at least 1.33 times the cross-sectional area of the body of the member. The net area beyond the pin hole of any section on either side of the axis of the member, measured at an angle of 45° or less to the axis of the member, shall be not less than 0.9 times the cross-sectional area of the member. The distance from the edge of the pin hole to the edge of the member, measured transverse to the axis of the member, shall not exceed four times the thickness of material at the pin hole. The diameter of the pin hole shall be not more than 1.0 mm larger than the diameter of the pin.

17.11 Compression members 17.11.1 Limiting slenderness for compression members Where the proportions of a compression member are to be limited to avoid excessive deflection under incidental lateral loads and vibrations, the following limits shall be observed: (a) for compression members: (i) chords: KL/r < 120; and (ii) diagonals: KL/r < 150; and (b) for members subjected to wind: (i) tubes: KL/r < 100; and (ii) double angles: b/t < 32 000/L. where b = the width of the wider leg of the component angles (see definition of b in Clause 17.9.1.1) t = the thickness of the wider leg of the component angles, mm L = unbraced length of the member, mm

17.11.2 Buckling 17.11.2.1 Normalized slenderness The normalized slenderness, l , shall be taken as

l=

Fo ⎛ l ⎞ Fo =⎜ ⎟ Fe ⎝ p ⎠ E

where Fo = limiting stress given in Clause 17.11.2.2, MPa 2 Fe = elastic buckling stress = p E , MPa l2

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The slenderness, , is that obtained from Clause 17.9 or 17.11, whichever governs for the section under investigation. The normalized slenderness, l , shall be used in Clause 17.11.2.3 to determine the normalized buckling stress, F = Fc /Fo , from which the actual buckling stress, Fc , is obtained.

17.11.2.2 Limiting stress The limiting stress, Fo , used in determining the buckling stress, Fc , shall be taken as one of the following: (a) when there is no welding or local buckling, the yield strength of the base metal: Fo = F y (b) when there is local buckling in an outstanding flange, the buckling stress, Fc , taken as Clauses 17.9.1.1, 17.9.1.2.2, and 17.11.2.3: Fo = Fc (c) when local buckling occurs in an element supported on two longitudinal edges, when the element is at the extreme fibre for the axis of flexure, the effective strength for the element, Fm , taken as Clause 17.8.4.3.1:

Fo = Fm = F Fy ⎛ l ⎞ Fy In this case, F shall be determined from Clause 17.11.2.3 with l = ⎜ ⎟ ⎝p⎠ E (d) in lattice columns, for the evaluation of the overall buckling capacity, the buckling stress of a chord, Fcc , taken as Clause 17.11.3: Fo = Fcc (e) when there is transverse welding at the ends of the member, the yield strength of the base metal (with a mean axial stress not greater than Fwu): Fo = Fy (f)

when there is a transverse weld away from the ends, the yield strength of the heat-affected zone, Fwy: Fo = Fwy

(g) when there is longitudinal welding, the effective strength, Fm , from Clause 17.8.4.2 (see also Clause 17.11.3.2.2): Fo = F m

17.11.2.3 Buckling stress The buckling stress, Fc , shall be taken as follows:

Fc = F Fo where

F = normalized buckling stress = b − b2 − where

(

1 l2

)

⎡1+ a l − lo + l 2 ⎤ ⎦ b= ⎣ 2l 2

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where

 = 0.2 for unwelded fully heat-treated columns, beams, and elements = 0.4 for all other columns, beams, and elements l = normalized slenderness, from Clause 17.11.2.1 lo = 0.3 for members = 0.5 for elements

Fo = limiting stress, MPa

Note: These relationships are plotted in Figure C17.15 of the Commentary for members and in Figure C17.16 for elements.

17.11.3 Members in axial compression 17.11.3.1 General The factored compressive resistance, Cr , of an axially loaded member shall be taken as follows:

C r = fy Ag F Fo The least of flexural buckling, torsional buckling and flexural-torsional buckling shall be considered.

17.11.3.2 Flexural buckling 17.11.3.2.1 General

For flexural buckling, the slenderness, , shall be taken as follows:

 = KL/r where K = effective length factor (see Table 17.4 for typical values)

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Table 17.4 Effective length factor, K (See Clauses 17.10.1 and 17.11.3.2.1.)

Member

Y

Kx k

Ky 1

AB AC

1

1

0.80

0.70

AB

0.50

0.50

0.45

0.40

AB

0.33

0.43

0.33

0.33

AB

0.25

0.35

0.25

0.25

AB

0.50

1

0.50

0.45

AB

0.50

1

0.50

0.45

AB

0.45

0.50

0.40

0.35

AB

V

L

X

A

kL

B

A L

Kv* (Single angles) 1 bolt 2 bolts

(1+ 2k ) 3

(1+ 2k ) 3

L

B

C

A L

C

T

T

C

B A C

T

C

T

B A C

T

C

T

B

A L B A C

B

T

A C

L T

B

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Table 17.4 (Concluded) Legend: C = Compression T = Tension T=C *See Clause 17.14.2.3.2.

The slenderness, , shall be used in Clause 17.11.2.1 with the applicable limiting stress, Fo , from Clause 17.11.2.2, to obtain the normalized slenderness, l . This normalized slenderness shall then be used in Clause 17.11.2.3 to obtain the normalized buckling stress, F , and subsequently the buckling stress, Fc = F Fo.

17.11.3.2.2 Influence of longitudinal welds The normalized buckling stress, F, obtained for longitudinally welded members [see Clause 17.11.2.2(g)] using Clause 17.11.2.3, shall be multiplied by the following additional factor:

k = 0.9 + 0.1 1 − l ≤ 1 where

1− l = the absolute value

17.11.3.3 Torsional buckling 17.11.3.3.1 All shapes To obtain the critical stress for pure torsional buckling of members of any shape, the slenderness shall be taken as

lt = p

EI p GJ

=5

Ip J

where Ip = polar moment of inertia about the shear centre, mm4 The normalized slenderness from Clause 17.11.2.1 shall be used in Clause 17.11.2.3 to give the normalized buckling stress, F . The factored compressive resistance, Cr , shall be taken as

C r = fy A F Fy

17.11.3.3.2 Sections composed of radial outstands

The slenderness, , for angles, T’s and cruciforms shall be given by (a) For simple angle sections, T-sections, and cruciforms, the slenderness shall be calculated as follows:

lt =

5b t

where b = the longest leg width, mm: for extruded sections, it is measured from the start of the root fillet; for formed angles, the leg width is measured from the intersection of the median lines of the adjacent walls (see Figure C17.17 of the Commentary) (b) For lipped equal angles of uniform thickness, the expression for the slenderness becomes

lt =

764

5b 1+ 3b t 1+ b

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where

b=

c b

(c) For bulb angles, Clause 17.11.3.3.1 shall apply.

17.11.3.3.3 All other open shapes

For all open shapes other than angles, T’s, and cruciforms, the slenderness, t, shall be given by

5 lt = 1+

Ip J 25Cw JL2

17.11.3.4 Flexural-torsional buckling For open sections symmetrical about one axis only, failure by flexure about the axis of symmetry shall combine with torsion. The slenderness, , shall be taken as

⎛x ⎞⎛l ⎞ l = l1 1+ ⎜ o ⎟ ⎜ 2 ⎟ ⎝r ⎠⎝l ⎠ o

2

1

where 1 and 2 = the slendernesses for flexural and torsional buckling, respectively, and 1 > 2 x0

= distance from centroid to shear centre, mm

r0

= polar radius of gyration about shear centre

17.12 Flexural members 17.12.1 Classification of members in bending Cross-sections of members in bending shall be classified, according to the compactness of the elements of the cross-section, as follows: (a) Class 1 sections are those capable of undergoing plastic strain in compression without local buckling. The sections shall be symmetrical about the plane of bending, be fully constrained against lateral buckling, and have l < 0.3. (b) Class 2 sections are those capable of carrying moment up to the onset of yielding in compression without local buckling. The sections shall be such that l < 0.5. (c) Class 3 sections are those in which there is local buckling below the yield stress with or without postbuckling reserve. This occurs when l > 0.5. Note: Lattice beams and masts, in which chord buckling controls overall flexural buckling, are Class 3.

17.12.2 Moment resistance of members not subject to lateral torsional buckling For members not subject to lateral torsional buckling, the factored moment resistance, Mr, in the plane of bending shall be as follows: (a) for Class 1 sections: (i) for compression fibres: Mr = y ZFy =  y Mp (ii) for tension fibres:

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Mr =  u Z n Fu (b) for Class 2 sections: (i) for compression fibres: Mr = y SFy =  y My (ii) for tension fibres: M r =  u Sn F u (c) for Class 3 sections: (i) when outstanding flanges, or chords in lattice masts, buckle in compression: Mr =  y S F F y (ii) when flat compression elements have two long edges supported: Mr = y Sm Fy where Z = plastic section modulus of the gross area, mm Mp = fully plastic moment, N•mm Zn = net plastic section modulus, mm3 = Z – (do t)i yi where do = hole diameter, mm t = element thickness, mm y = distance from the neutral axis of the gross cross-section to the centre of the bolt hole, mm S = elastic section modulus, mm3 My = moment at first yield, N•mm3 Sn = net elastic section modulus, mm3 = S – (do t)iyi F = normalized buckling stress for flanges (see Clauses 17.9 and 17.11.2.3) or chords, mm3 Sm = effective section modulus using the effective thicknesses (see Clause 17.8.3) For sections influenced by longitudinal welds, Mp and My shall be calculated using the appropriate effective section as taken as Clause 17.8.3.2.

17.12.3 Moment resistance of members subject to lateral torsional buckling 17.12.3.1 Members with lateral restraint of the tension flange only For members of all classes described in Clause 17.12.1, for bending about the strong axis (x-axis) with lateral restraint at the tension flange only, the factored moment resistance, Mr , shall be taken as Mr =  y S x F F o where Sx = section modulus about the strong axis, mm3

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F

= normalized buckling stress, from Clause 17.11.2.3, using the limiting stress, Fo , and the slenderness, , taken as (a) for the general case:

l=

Sx d 0.04 J +

Cw L2

(b) for I-sections, channels, and plate girders:

l=

L ry ⎛ Lt ⎞ 1+ 0.5 ⎜ ⎟ ⎝ bd ⎠

2

(c) for deep rectangular solid or hollow sections:

⎛r ⎞ l =⎜ x⎟ ⎝ ry ⎠

2.8 ⎛d⎞ 0.64 + ⎜ ⎟ ⎝L⎠

2

(d) where the tension flange is firmly attached to an element, with bending resistance that can provide elastic restraint to the twisting of the member, the slenderness becomes

10Sx

l= 0.4

Iy Im J + d a

where Sx = section modulus about the strong axis, mm3 d = member depth, mm Cw = warping constant for rotation about the point of restraint, mm6 L

= distance between points of full lateral restraint, mm

ry = radius of gyration about the weak axis, or, for unsymmetrical I-sections, of the compression flange plus 1/6 of the web area, mm t

= flange thickness, mm

b = overall flange width, mm rx = radius of gyration about the strong axis, mm Iy = moment of inertia about the weak axis of the member, mm4 Im = moment of inertia per unit width of the supported medium, mm4/mm a = distance between the parallel members supporting the medium, mm

17.12.3.2 Unrestrained members For unrestrained members bending about the strong axis (x-axis), which are subject to lateral torsional buckling, the factored moment resistance, Mr , for all classes described in Clause 17.12.1, shall be given by the applicable formula in Clause 17.12.3.1, in which the normalized buckling stress, F , shall be obtained from Clause 17.11.2.3 using the limiting stress, Fo , and the slenderness, , given by the following: (a) for the general case:

Sx L

l= 4I

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Cw ⎞ ⎛ ⎜⎝ 0.04 J + 2 ⎟⎠ L

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(b) for I-sections, channels, and plate girders:

L ry

l= 4 1+

⎛ Lt ⎞ ⎜⎝ ⎟⎠ bd

2

(c) for deep rectangular solid or hollow sections:

⎛r ⎞ L l = 2.2 ⎜ x ⎟ ⎝ ry ⎠ d where L = distance between points of full lateral or torsional restraint, mm b = overall flange width, mm

17.12.3.3 Members with end moments For members subjected to a moment gradient, with factored end moments of Mmax and Mmin, the value of the moment, which shall not exceed the factored moment resistance, Mr , in Clause 17.12.3.1 or 17.12.3.2 as appropriate, shall be taken as follows: Mm = 0.6 Mmax + 0.4 Mmin , but not less than 0.4 Mmax For members bent in double curvature, Mmin shall be negative.

17.12.4 Webs in shear — Flat elements 17.12.4.1 Buckling stress For a flat rectangular element with boundary flanges or stiffeners, subjected to shear force, the initial buckling stress, Fsc , shall be as follows: Fsc = Fo F where Fo = limiting stress equal to the shear yield strength, MPa = 0.6 Fy

F = normalized buckling stress from Clause 17.11.2.3, obtained with the following normalized slenderness: ls Fo p E where

l=

ls =

⎛b⎞ 1.4 ⎜ ⎟ ⎝w⎠ ⎛ b⎞ 1+ 0.75 ⎜ ⎟ ⎝ a⎠

2

(see Figure C17.20 of the Commentary)

where b = smaller panel dimension, mm w = web thickness, mm a = larger panel dimension, mm

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17.12.4.2 Limiting shear resistance at the boundaries

The factored shear resistance per unit length, vr = vs, of connections between the web and the flange, or of any seams in the web, or along attachments of stiffeners shall be the least of the appropriate values: (a) vr = y 0.6Fy w ; (b) vr = u 0.6F wu w, but not greater than the factored resistance of the fillet welds; (c) vr = f Rk /s, but not greater than u 0.6(1 – do /s)Fu w for seams with mechanical fasteners; and (d) vr = uvk where Fwu = ultimate tensile strength in the heat-affected zone at a weld (see Table 17.3), MPa Rk

= characteristic resistance of a fastener, N

s

= spacing of fasteners along a line of connection, mm

vk

= characteristic ultimate shear resistance per unit length of a joint or seam (riveted or bonded), N/mm

vs

= shear resistance per unit length

17.12.4.3 Stiffened webs 17.12.4.3.1 Stiffener locations Stiffened webs shall have stiffeners at the points of support and at any local applied forces. Other transverse and longitudinal stiffeners may be added to increase the initial buckling stress.

17.12.4.3.2 Shear resistance For webs that buckle before yielding, the factored shear resistance, Vr , shall be the lesser of the following values taken as:

⎡ ⎤ v Vr = fk ⎢2 Fsc s − Fsc ⎥ hw ; and w ⎣ ⎦ (b) Vr = vrh (a)

where Fsc = buckling stress in shear from Clause 17.12.4.1, MPa vs,vr = characteristic ultimate shear resistance per unit length of the boundaries or seams (see Clause 17.12.4.2), N/mm h

= web depth, mm

For webs with longitudinal and transverse stiffeners, the value for Fsc shall be that for the panel, in the section considered, with the lowest initial buckling stress.

17.12.4.4 Web stiffeners Stiffeners shall be designed to carry a factored axial force, Nf , taken as (a) for transverse stiffeners, Nf is the greater of the shear force at the stiffener due to the factored loads and the local factored load applied to the top flange or the support reaction; and (b) for longitudinal stiffeners,

Nf = v r a F where vr = factored ultimate shear resistance per unit length at the boundaries from Clause 17.12.4.2, N/mm a F

= length between transverse stiffeners, mm = normalized buckling stress from Clause 17.12.4.1

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Stiffeners on one side only shall be treated as eccentrically loaded. A 25w width of the web plate may be assumed to act with the stiffener. If longitudinal stiffeners accept axial force due to overall bending, the force shall be added to that required for stability under shear forces.

17.12.4.5 Combined shear and bending in webs ln continuous beams with web stiffeners over the supports, if no buckling is to occur, the limiting condition is 2

2

⎛ fbf ⎞ ⎛ fsf ⎞ ⎟ ≤ 1.0 ⎟ +⎜ ⎜ ⎝ fy Fbc ⎠ ⎝ fy Fsc ⎠ where fsf = factored applied shear stress, MPa Fsc = buckling stress in shear from Clause 17.12.4.1, MPa fbf

= factored longitudinal compressive stress in web due to the overall bending moment

Fbc = local web buckling stress due to compression caused by bending from Clause 17.11.2.3, MPa, using the slenderness, , from Clause 17.9.1.2.2 and the limiting stress, Fy lf this condition is not satisfied, then the web shall be assumed to carry shear force only, satisfying Clause 17.12.4, and the flanges shall be assumed to carry the bending moment.

17.12.4.6 Web crippling The factored resistance, Cr , for a local compressive force acting in the plane of the web shall be determined using one of the following formulas: (a) for flat webs Cr = y k (n + h) wF’c  y n w Fy where

⎡ ⎤ e ⎢1+ ⎥ k = 0.5 ⎢ ⎛ n + h⎞ ⎥ ≤ 1.0 ⎟⎠ ⎥ ⎢ ⎜⎝ 2 ⎢⎣ ⎥⎦ where e = distance from the centre of bearing to the end of the beam, mm n = bearing length, mm

Fc′ =

2 p 2E w 2 ⎡ ⎛ fbf ⎞ ⎤ ⎢ ⎥ − 1 4h 2 ⎢⎣ ⎜⎝ Fbc ⎟⎠ ⎥⎦

where fbf = factored longitudinal compressive stress due to the overall bending moment, MPa Fbc = web buckling stress for bending from Clause 17.11.2.3, MPa, using the slenderness from Clause 17.9.1.2.2 and the limiting stress, Fy (b) for webs with bent radii at the corners:

(

)

n⎞ ⎛ R⎞ ⎛ C r = fy k ⎜ 11 + 0.07 ⎟ ⎜ 1 − 0.0008q ⎟ Fy − fbt t 2 ⎝ t⎠⎝ t⎠

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where

⎛ ⎞ e ⎟ ⎜ k = 0.5 ⎜ 1+ ⎟ ≤ 1.0 n + h⎟ ⎜⎝ ⎠ 2 n

= bearing length, mm

t

= element thickness, mm



= acute angle between web and bearing surface, degree

R

= interior bend radius, mm

ƒbt = longitudinal compressive stress at the bearing point due to the factored moment, MPa e

= distance from the centre of bearing to the end, mm

h

= web depth, mm

17.13 Members in torsion 17.13.1 General Members and their connections subjected to torsion shall have sufficient strength and rigidity to resist the torsional moments and forces in addition to other moments and forces. The torsional deformations at the SLS shall be within acceptable limits.

17.13.2 Hollow sections 17.13.2.1 Torsional resistance The factored torsional resistance for hollow sections, Qr , taking the warping constant, Cw , to be zero, shall be calculated as Qr = y 1.2 A’t Fy where A’ = area enclosed by the median line of the walls, mm2 t

= minimum thickness, mm

This equation is based on full plastic capacity in torsion. If full plastic capacity cannot be developed due to buckling, the torsional resistance shall be calculated using an elastic analysis.

17.13.2.2 Combined axial compression, flexure, and torsion Members of closed cross-section subjected to combined axial compression, flexure, and torsion shall be proportioned so that

Cf + Cr

2

⎛Q ⎞ + ⎜ f ⎟ ≤ 1.0 ⎛ C ⎞ ⎝ Qr ⎠ Mr ⎜ 1 − f ⎟ ⎝ Ce ⎠ Mf

where Cr

= as specified in Clause 17.11

Mr = as specified in Clause 17.12 Qf = the factored applied torsional load Qr = as specified in Clause 17.13.2.1

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17.13.3 Members of solid compact cross-section The factored torsional resistance for solid compact bars shall be calculated as

Qr =

fy Aa Fy 5

where A = area of cross-section, mm2 a = least dimension across the section, mm

17.13.4 Members of open cross-section 17.13.4.1 Torsional resistance for sections without warping resistance For open shapes without warping restraint,

Qr =

( )

fy ∑ bt 3 Fy 5tmax

where b = width of individual wall, mm t

= thickness of individual wall, mm

tmax = maximum thickness, mm

17.13.4.2 Torsional resistance for sections with warping resistance The factored torsional resistance of members of open cross-section shall be calculated based on accepted principles of elastic torsional analysis, taking into account the St. Venant and warping torsional resistance as a function of the loading and restraint conditions.

17.13.4.3 Combined bending and torsion For sections with warping restraint, the total longitudinal stress due to the warping rigidity shall be added to any simultaneous bending stress. The total longitudinal stress due to the factored load shall not exceed y Fy. For I-shaped members subject to torsion or combined bending and torsion, the maximum combined normal stress due to warping torsion and bending at SLS loads, as determined by an elastic analysis, shall not exceed Fy .

17.14 Members with combined axial force and bending moment 17.14.1 Axial tension and bending 17.14.1.1 Elastic behaviour The limiting combination of axial tension force, Tf , and factored bending moment Mf , shall be taken as

Mf Tf + ≤ 1.0 Mr Tr The values shall conform to one of the following: (a) Mr is for Class 1 sections limited by compression fibres, from Clause 17.12.2(a)(i), and Tr is from Clause 17.10.3(a); or (b) Mr is for Class 1 sections limited by tension fibres, from Clause 17.12.2(a)(ii), and Tr is from Clause 17.10.3(b).

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If welded, the effective thickness determined from Clause 17.8.3.2 shall be used when calculating the geometric properties. Holes in the tension zone shall be deducted from members in bending to give net section modulus. No adjustment need be made in the position of the centroid of the cross-section.

17.14.1.2 Plastic behaviour Where a fully plastic condition is permitted, for a flat plate or solid bar, the limiting combination of axial tension force, Tf , and factored bending moment Mf , shall be taken as 2

Mf ⎛ Tf ⎞ + ≤ 1.0 Mr ⎜⎝ Tr ⎟⎠

17.14.1.3 Stability Where the factored axial tension force, Tf, helps to stabilize a member against lateral buckling caused by applied factored moment, Mf , the limiting combination for stability shall be taken as 2

⎛ Mf ⎞ Tf ⎜⎝ M ⎟⎠ − C ≤ 1.0 r e where Mr = factored moment resistance for unrestrained member from Clause 17.12.3.2, N•mm

Ce =

p 2 AE ⎛ KL ⎞ ⎜r ⎟ ⎝ y⎠

2

17.14.2 Axial compression and bending 17.14.2.1 Members not subject to lateral torsional buckling For members not subject to lateral torsional buckling, the limiting combination of factored axial load, Cf , and factored bending moment, Mf , shall be calculated using the gross section and shall be such that (a) where compressive stress governs,

Mf ⎛ C ⎞ Sc ⎜ 1− f ⎟ ⎝ Ce ⎠

+

Cf ≤ fy Fo A

(b) where tensile stress governs,

Mf ⎛ C ⎞ St ⎜ 1− f ⎟ ⎝ Ce ⎠

−

Cf ≤ fy Fy A

(c) for members with applied end moments, the limiting combination at the supports shall be calculated using the following formulas: (i) when compressive stress governs,

Mfmax Cf + ≤ fy Fy Sc A (ii) when tensile stress governs,

Mfmax Cf − ≤ fy Fy St A

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where = maximum moment due to the factored lateral load, N•mm Mf = 0 .6M1+ 0.4M2 > 0.4M1 for moment gradients M1, M2 = the applied moments due to the factored loads; they are of opposite signs when they cause a reversal of curvature along the beam (M1 > M2), N•mm Cf

= applied compressive force due to the factored load, which shall not exceed the value for Cr taken as Clause 17.11.3.1, N

Sc

= section modulus of the extreme fibre in compression, mm3

St

= section modulus of the extreme fibre in tension, mm3

Ce

=

p2 E A l2

L r Mf max = maximum factored end moment, N•mm (d) for members subjected to axial force combined with bending about both principal axes, where the maximum stress from both moments occurs at the same location of the cross-section and the member fails in flexure, the limiting condition shall be taken as



=

Mfx

+

⎛ C ⎞ Sx ⎜ 1 − f ⎟ ⎝ C ex ⎠

Mfy ⎛ C ⎞ Sy ⎜ 1 − f ⎟ ⎝ C ey ⎠

+

Cf ≤ fy Fo A

where Mfx = moment in the member due to the factored lateral load, about the strong axis, N•mm Mfy = moment in the member due to the factored lateral load, about the weak axis, N•mm Sx = section modulus of the gross section about the strong axis, mm3 Sy = section modulus of the gross section about the weak axis, mm3

C ex =

p 2E A lx2

where

lx =

C ey =

L rx p 2E A ly2

where

ly =

L ry

17.14.2.2 Members subject to lateral torsional buckling For members subject to lateral torsional buckling with combined axial force and bending about the strong axis, the combined factored axial load, Cf , and bending moment, Mf , shall satisfy

Mf ⎛ C ⎞ Mr ⎜ 1 − f ⎟ ⎝ C ex ⎠

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where Mr = factored moment resistance obtained from Clause 17.12.3.1 or 17.12.3.2, as applicable, N•mm Cry = factored resistance for failure about the weak axis, obtained from Clause 17.11.3.1, N

17.14.2.3 Eccentric compression 17.14.2.3.1 General case For general cases of eccentric compression, the following requirements shall apply: (a) For failure in the plane of bending, Clause 17.14.2.1(a) or (b) shall be used with a factored moment, Mf, taken as Mf = 1.2eCf (b) For lateral torsional buckling, Clause 17.14.2.2 shall be used with a moment, Mf , taken as Mf = eCf where e = eccentricity, mm Cf = applied compressive force due to the factored loads, N

17.14.2.3.2 Single angle members For single angle members, (a) the factored compressive resistance, Cr , of discontinuous single angles connected through one leg shall be taken as Clause 17.11.3.1, using

l = lv 2 + lt 2 lv =

KL rv

5b t where rv = minimum radius of gyration, mm b = width of longer leg (see Clause 17.11.3.3.2), mm t = thickness of longer leg, mm (b) the factored resistance, Cr , shall not exceed (i) y 0.5AFy for single bolt connections; or (ii) y 0.67AFy for double bolt or welded connections. lt =

17.15 Built-up compression members 17.15.1 Spacing of connectors In members composed of battened channels, double or quadruple angles stitch-bolted or tack-welded together, and latticed masts, the slenderness of the individual members between the interconnections shall not exceed 0.75 times that of the overall member.

17.15.2 Multiple-bar members with discrete shear connectors For members composed of two or more bars, connected together at discrete intervals by fasteners, battens, or welds, that buckle in the built-up plane so as to cause shear in the connectors (see Figure C17.23 in Commentary), there shall be at least four interconnectors: one at each end and two within the length of the member.

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The factored compressive resistance, Cr , shall be from Clause 17.11.3.1 using Fo = Fy and the slenderness, , taken as

l = lo 2 + la 2 where KL lo = r′

a r r’ = radius of gyration of the total section for the built-up axis, mm a = distance from centre to centre of the interconnections, mm r = radius of gyration of a single element bending in the plane of failure, mm Interconnections shall be designed to resist a total shear force at each location of Cf I40. la =

17.15.3 Double angle struts Where the torsional flexibility of double angles influences the stability, the factored compressive resistance, Cr , for combined buckling about the built-up axis and torsional buckling shall be obtained from Clause 17.11.3.1 using the slenderness, , taken as

l = l12 + 0.5l22 where

1 = greater value of f and t 2 = lesser value of f and t where  f = slenderness for flexural buckling from Clause 17.15.2

 t = slenderness for torsional buckling 5b = t where b = width of the longer leg (see Clause 17.11.3.3.2), mm

17.15.4 Lattice columns and beam-columns The following requirements shall apply: (a) The slenderness, , of a lattice column shall be taken as

l=

L r

where L = length of column, mm r = radius of gyration of the total cross-section, mm The limiting stress, Fo, for use in Clause 17.11.2.3 shall be the buckling stress for the chord [see Clause 17.11.2.2(d)].

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(b) The limiting combination of factored axial load, Cf , and factored moment, Mf , for a lattice beam-column failing in the plane of bending, shall be taken as

Mf ⎛ C ⎞ kd ⎜ 1− f ⎟ ⎝ Ce ⎠

+

Cf ≤ Cr N

(c) The maximum shear force in a beam-column shall be taken as

Vmax =

Vf ⎛ Cf ⎞ ⎜⎝ 1 − C ⎟⎠ e

where Mf = factored bending moment at ULS, N•mm k = for square sections, 1.4 or 2, depending on the direction of bending = for triangular sections, 0.85, 1.0, or 1.7, depending on the direction of bending d = face width, mm

Ce =

p 2 EA l2

where A = total area of all chords, mm2

l=

L r

where L = unbraced length of column, mm r = overall radius of gyration of the cross-section of the lattice member, mm = d/2 for rectangular sections = d/ 6 for triangular sections N = number of chords Cr = factored compressive resistance of one chord, from Clause 17.11.3.1, N

17.16 Composite beams and girders 17.16.1 General Clause 17.16 shall apply to structures consisting of aluminum beams or girders and a concrete slab in which resistance to shear at the interface between the beams or girders and the slab is provided by mechanical shear connectors. Bridges shall be unshored during placement of the slab. It shall apply to aluminum beams and girders that are both symmetric and asymmetric about the major axis. Where the beams are shored during casting of the deck, the design methods used shall be subject to Approval. This section covers only single span bridges. The use of continuous spans shall require Approval. Other types of composite beams and girders shall be designed so that the connections between the deck and girder are sized for the shear at that connection.

17.16.2 Concrete slab Contact surface between the aluminum beams or girders and the slab shall comply with Clause 17.6.1. The type of concrete, its strength and other properties, and provisions for control of cracking shall comply with Section 8. Allowances shall be made for the stresses and deformations induced by the difference between the coefficients of linear thermal expansion of the concrete deck and the aluminum girder.

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17.16.3 Proportioning The aluminum section alone shall be proportioned to support all factored loads applied before the concrete strength reaches 0.75f’c . The lateral restraint conditions existing when the different loads are applied shall be taken into account. The web of the aluminum section shall be designed to carry the total vertical shear and shall meet the requirements of Clause 17.12.4. The effective slab width, Be, shall be determined in accordance with Clause 5.8.2.1.

17.16.4 Effects of creep and shrinkage To account for the effect of creep due to that portion of dead load that is applied after the concrete strength has reached 0.75 f’c , and in lieu of more detailed calculations, a modular ratio of 3n shall be used in calculating the section properties. For the SLS, a differential shrinkage strain corresponding to the difference between the restrained and the free shrinkage of the concrete shall be considered in the design.

17.16.5 Control of permanent deflections For composite beams and girders, the normal stress in either flange of the aluminum section due to serviceability dead and live loads shall not exceed 0.90Fy . The following requirement shall also be satisfied:

Md Msd ML + + ≤ 0.9 Fy S S3n Sn where Md = bending moment in beam or girder at SLS due to dead load, N•mm Msd

= bending moment in beam or girder at SLS due to superimposed dead load, N•mm

ML

= bending moment in beam or girder at SLS due to live load, N•mm

S

= elastic section modulus of aluminum section, mm3

Sn, S3n = elastic section modulus comprising the aluminum beam or girder and the concrete slab, calculated using a modular ratio of n or 3n, respectively, mm3 = modular ratio = Ea/Ec

n

where Ea = modulus of elasticity of aluminum, MPa Ec = modulus of elasticity of concrete, MPa When welds are present in the section, the effective section modulus using the effective thickness of the section shall be used.

17.16.6 Resistance of composite section 17.16.6.1 Stress distribution The factored moment resistance of the section in bending shall be calculated using a fully plastic stress distribution, as shown in Figure 17.2.

17.16.6.2 Compressive resistance of concrete The factored compressive resistance of the slab used to calculate the factored resistance of the section shall be the smaller of C1 and C2, calculated as follows: C1 = Cc + Cr C2 = y Aa Fy where Cc = 0.85c Be tc f’c Cr = r Ar fy

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where Cc = factored compressive resistance of concrete, N Cr = factored compressive resistance of reinforcing steel, N Aa = area of aluminum section, mm2 Be = effective width of concrete slab, mm tc = thickness of concrete slab, mm f’c = specified compressive strength of concrete, MPa Ar = area of reinforcing steel within the effective width of a concrete slab, mm2 fy = specified minimum yield strength of reinforcing steel, MPa When welds are present in the aluminum section, the effective area using the effective thickness of the section shall be used.

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Compression zone φ y fy , 0.85φ cfc

Be Ar

Cr a Plastic neutral axis of composite section

tc

yt d yb

, ds

Cc ec er

Neutral axis of aluminum beam

Ta

φ yFy

(a) Plastic neutral axis in the concrete slab

φ yfy

Be Ar tc tt ytc d ybc

, ds

, 0.85φ cfc

Cr

, yt

Cc Ca

dc Plastic neutral axis of composite section

Aa

ec

er

φ yFy h Ta

tb

, yb

φ y Fy

(b) Plastic neutral axis in the aluminum section

Figure 17.2 Stress distribution in composite sections (See Clauses 17.16.6.1, 17.16.6.3, and 17.16.6.4.)

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17.16.6.3 Plastic neutral axis in concrete When C1 is greater than C2, the plastic neutral axis is in the concrete slab, as shown in Figure 17.2(a), and the depth of the compressive stress block, a, shall be calculated as

a=

C 2 − fr Ar fy 0.85 fc Be fc’

The factored moment resistance, Mr , of the section shall be calculated as M r = C c ec + C r er where Cc = 0.85c Be af’c ec = lever arm between the factored tensile resistance and the factored compressive resistance of the concrete, mm er

= lever arm between the factored tensile resistance and the factored compressive resistance of the reinforcing steel, mm

17.16.6.4 Plastic neutral axis in aluminum When C1 is less than C2 , the plastic neutral axis is in the aluminum section, as shown in Figure 17.2(b), and the depth of the compressive stress block, a, shall be taken as equal to tc . The compression flange of the aluminum section shall be designed to develop full plastic stress without buckling. The normalized slenderness of the compression flange, lo , shall be not greater than 0.5 for a uniform stress distribution, which results in the following element slenderness, where b is the half width of the flange:

b 83 ≤ t Fy The depth of the compression portion of the web of the aluminum section, dc , calculated on the basis of a fully plastic stress distribution, shall not exceed the following value where w is the web thickness:

dc ≤

250w Fy

The factored moment resistance, Mr , shall be calculated as Mr = C c ec + C r er + C a ea where Cc = 0.85c Be tc f’c Cr = r Ar fy Ca = 0.5 (y Aa Fy – C1) ea = lever arm between the tensile resistance and the compressive resistance of the aluminum, mm When a stiffened plate girder is used as supporting member, the flange shall satisfy the slenderness limit given above and the contribution of the compression portion of the web shall be neglected in flexure.

17.16.7 Shear connectors 17.16.7.1 General Shear connectors shall comply with the applicable materials specification of Clause 17.4 and shall be capable of resisting both horizontal and vertical movements between the concrete slab and the aluminum beam or girder. Shear connectors shall comply with the requirements of CSA W59.2.

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The fatigue resistance of the base metal at the connection weld of shear connector shall comply with Clause 17.20. Ultimate and fatigue resistances of the shear connectors shall be evaluated. Method to determine the fatigue resistance of shear connectors shall require Approval.

17.16.7.2 Longitudinal shear The longitudinal factored shear resistance along any potential shear planes shall be greater than the factored longitudinal shear. The longitudinal shear resistance of the slab shall be checked in accordance with Clause 10.11.8.4.

17.16.7.3 Lateral bracing, cross-frames, and diaphragms The requirements of Clause 10.10.9 shall be met.

17.17 Trusses 17.17.1 General 17.17.1.1 Truss Members Main truss members shall be symmetrical about the centroidal longitudinal vertical plane of the truss. When the centroidal axes of axially loaded members joined at their ends do not intersect at a common point, the effect of connection eccentricity shall be taken into account.

17.17.1.2 Camber The fabricated length of members shall be such that the resulting camber of the truss is in accordance with Clause 17.7.3.

17.17.1.3 Connections Design of connections shall be in accordance with Clauses 17.10, 17.22, and 17.23.

17.17.2 Built-up members Built-up members shall comply with Clauses 17.10 and 17.15.

17.17.3 Bracing 17.17.3.1 Top and bottom bracing Through-truss spans, deck-truss spans, and spandrel-braced-arch spans shall have top and bottom lateral bracing systems.

17.17.3.2 Chord bracing The use of lateral bracing shallower than the chords shall require Approval. Bracing shall be connected effectively to both flanges of the chords.

17.17.3.3 Through-truss spans Through-truss spans shall have portal bracing rigidly connected to the end post and top chord flanges. Portal bracing shall be proportioned to take the full reaction of the top chord lateral system and the end posts shall be proportioned for the reaction. Through-truss spans shall have sway bracing at each intermediate panel point.

17.17.3.4 Deck-truss spans Deck-truss spans shall have sway bracing in the plane of the end posts and at all intermediate panel points. Sway bracing shall extend the full depth of the trusses below the floor system. The end sway bracing shall be proportioned to carry all of the upper lateral forces to the supports through the end posts of the truss.

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17.17.3.5 Minimum force Bracing systems between straight compression members or straight flanges shall be designed to carry the shear forces from external loads plus 1% of the compression forces in the supported members or flanges.

17.17.3.6 Half-through trusses and pony trusses The top chord of a half-through or pony truss shall be designed as a column with elastic lateral supports at each panel point. The factored compressive resistance of the column shall be at least equal to the maximum force in any panel of the top chord resulting from loads at the ULS. For highway bridge truss systems, the vertical truss members, floor beams, and connections between them shall be proportioned to resist at the ULS a lateral force of at least 8 kN/m applied at the top chord panel points. The minimum lateral force for pedestrian bridge truss systems applied to vertical members shall be taken as 0.01/K > 0.003 times the average factored compression force in two adjacent top chords at panel points, where K is the effective length factor for the individual top chords supported between the truss verticals.

17.18 Arches 17.18.1 General The design of solid web arch ribs at the ULS shall be based on an amplified first-order analysis or a second-order analysis in accordance with Section 5 and take into account the deformations that occur at the ULS load levels.

17.18.2 Width-to-thickness ratios The width-to-thickness ratio of flanges and webs of arch ribs shall be used in accordance with Clause 17.9 for calculating slenderness of elements to obtain bucking stress and member resistance in accordance with Clauses 17.11, 17.12, and 17.13.

17.18.3 Longitudinal web stiffeners For a web with longitudinal stiffener used to increase stability under bending compression, the local buckling factor m, in Clause 17.9.1.2.2, shall be taken as 0.29 where f2/f1< 0. The moment of inertia of such longitudinal stiffener shall satisfy the following:

Is ≥

0.02f a wh3 E

2 ⎡⎛ ⎤ 6A ⎞ ⎛ s ⎞ + 0.4⎥ ⎢ ⎜ 1+ ⎟ ⎜ ⎟ ⎢⎣⎝ hw ⎠ ⎝ h ⎠ ⎥⎦

where Is = moment of inertia of the longitudinal stiffener about the web of the beam, mm4 f

= un-factored compressive stress at toe of flange, MPa

 = 1.0 for stiffener consisting of equal members on both sides of the web = 3.5 for stiffener consisting of member on only one side of the web A = gross area of cross-section of longitudinal stiffener, mm2 s

= distance between transverse stiffeners, mm

Longitudinal stiffeners shall be located so that the distance from the toe of compression flange to the centroid of the stiffener is 0.4 times the distance from the toe of the compression flange to the neutral axis of the beam (see Figure C17.26 in the Commentary). For a stiffener consisting of a member on one side only, the moment of inertia shall be taken about the face of the web in contact with the stiffener. For a stiffener consisting of equal elements on both sides of the web, the moment of inertia shall be the sum of the moments of inertia about the centreline of the web. Web stiffeners for stability under shear forces shall be designed in accordance with Clause 17.12.4.3.

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17.18.4 Axial compression and bending Arch ribs required to resist bending moments in addition to an axial compressive force shall be proportioned to comply with Clause 17.14.2.

17.18.5 Arch ties Arch ties shall be considered fracture-critical members unless constructed of several components in such a manner that a fracture of one component does not propagate into another.

17.19 Decks 17.19.1 General Stiffened aluminum decks shall consist of a deck plate stiffened by ribs and transverse floor beams. If ribs are welded to the deck plate, the effective thickness shall be considered in the heat-affected zone in accordance with Clauses 17.8.3.2 and 17.8.4.2. Aluminum decks shall be considered to act compositely with steel or aluminum girders where the connection of the deck to the girders is sized for the shear at the connection.

17.19.2 Effective width of deck Unless calculated by an approved method, the effective width of deck plate acting as the top flange of a longitudinal rib shall not exceed the rib spacing or one third of the span.

17.19.3 Superposition of local and global effects Where the deck is composite with the girders, in calculating force effects in the deck, the global or overall effects induced by flexure and axial forces in the main longitudinal girders and the local effects for the same configuration and position of live load shall be superimposed.

17.19.4 Longitudinal flexure Effective section or effective strength in accordance with Clause 17.8 with consideration of local buckling for cross-section elements and heat affected zones shall be considered for calculation of moment resistance of the deck in longitudinal direction. The flexibility of the supports shall be considered in determining the longitudinal moments in continuous decks. Longitudinal ribs including an effective width of deck plate shall be investigated for stability as individual beam-columns assumed as simply supported at transverse beams.

17.19.5 Transverse flexure In determining the transverse moments, the effects of torsional rigidity of the ribs may be included when ribs are torsionally stiff.

17.19.6 Decks in longitudinal compression The factored compressive resistance, Cr , of a flat element with multiple stiffeners, loaded in the direction of stiffening, shall be obtained from Clause 17.11.3 using the appropriate value of the slenderness, , taken as (a) for general case, the lesser of L (i) l = ; or r ⎛ b⎞ I (ii) l = 1.3 ⎜ ⎟ 4 3 ⎝r⎠ t where L = panel length between transverse supports, mm r = radius of gyration of the gross stiffened section, mm b = panel width perpendicular to the direction of the stiffeners, mm

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= moment of inertia per unit width of the gross stiffened section, mm4/mm

I

t = element thickness, mm (b) for an element with open stiffeners, supported on all four edges:

Ae E Ncr

l=p

where Ae = effective area of the element cross-section, allowing for local buckling and HAZ softening due to longitudinal welds, mm2 Ncr = elastic orthotropic buckling load based on the gross cross-section, given by Ncr , taken as

Ncr =

p 2EIy 2

L

+

L2c p

Ncr = 2 cEIy

2

if L < p 4

if L ≥ p 4

EIy c

EIy c

where c = elastic support from the element, taken as (i)

for an element with one central or eccentric stiffener [Figure 17.3(f)]:

c=

0.27 Et 3b b12b22

(ii) for an element with two symmetrical stiffeners [Figure 17.3(g)]:

c=

1.1 Et 3

b12 (3b − 4b1)

(iii) for a multi-stiffened element with open stiffeners with small torsional stiffness [Figure 17.3(b),(c),(h),(i)]:

c=

8.9 Et 3 b3

If the element buckles between the stiffeners (see Clause 17.9.2), the limiting stress, Fo , shall be the effective strength, Fm , for the buckled elements, obtained from Clause 17.8.4.3.1, which is used in Clause 17.11.3 to give the overall buckling force.

17.19.7 In-plane moment in decks The factored in-plane moment resistance, Mr, of a flat element with multiple transverse stiffeners shall be taken as

Mr = fy FFy

Ieff y st

where Ieff = moment of inertia of the effective cross-section for in-plane bending, mm4 yst = distance from centre of deck to centre of outermost stiffener, mm (see Figure 17.3) The entire cross-section shall be treated as a beam under in plane bending. The factored moment resistance, Mr , shall be based on the least favourable cross-section, taking into account local buckling, HAZ and holes. Normalized slenderness should be determined based on slenderness, , given in Clause 17.19.6.

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17.19.8 In-plane shear in decks The factored in-plane shear resistance, Vr , of a flat element with multiple transverse stiffeners shall be taken as Vr = y F (0.6Fy)ht where h

= width of element in the direction of the shear force, mm

F

= normalized buckling stress obtained from Clause 17.11.2.3, for plates of the appropriate alloy type, using the limiting stress Fo = 0.6Fy and the slenderness, , taken as

l

= 0.8b 8

t I3

where b = element dimension in the direction of the stiffeners, mm t = element thickness, mm I = moment of inertia per unit width of the stiffened element, mm4/mm

17.19.9 Wearing surface The wearing surface shall not be regarded as an integral part of the deck and the contribution of a wearing surface to the stiffness of the members of a deck shall be ignored.

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MEd

NEd

(a)

VEd (f)

x

y

y b2

b1 b (g) b2 b

b1

yst

L

2a

b1

(h) 2a b y b

(i)

(b) (j)

(c) (d)

(k) (e)

(i) open stiffeners, (j) closed stiffeners, (k) combined stiffeners

Figure 17.3 Stiffened plates and type of stiffeners (See Clauses 17.19.6 and 17.9.7.)

17.20 Structural fatigue 17.20.1 General The FLS considered shall include direct live load effects (i.e., live load-induced fatigue) and the effects of local distortion within the structure (i.e., distortion-induced fatigue).

17.20.2 Live-load-induced fatigue 17.20.2.1 Calculation of stress range The stress range for load-induced fatigue shall be calculated using ordinary elastic analysis and the principles of mechanics of materials. A more sophisticated analysis shall be required only in cases not covered in Table 17.8, such as major access holes and cutouts. Because the stress range shall be the algebraic difference between the maximum stress and minimum stress at a given location, only the stresses due to live loads shall be considered. At locations where the stresses resulting from the permanent loads are compressive, load-induced fatigue shall be disregarded when the compressive stress is at least twice the maximum tensile live load stress.

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17.20.2.2 Design criteria for CL-W loading 17.20.2.2.1 For load-induced fatigue, except in bridge decks, each detail shall satisfy the following:

CLfsr < Fsr where  = damage equivalence factor as specified in Table 17.5 CL = 1.0 , except when W > 625 kN and the volume of heavy trucks prompting the use of a level of loading greater than that for CL-625 Trucks constitutes not more than the greater of 200 per day and 5% of the ADTT on the highway, CL = 0.20 + 500/W W = gross weight of the CL-W Truck as specified in Clause 3.8.3.2, kN fsr = calculated fatigue stress range at the detail due to passage of the CL-W Truck, as specified in Clause 3.8.3.2, MPa Fsr = fatigue stress range resistance, MPa

17.20.2.2.2 For load-induced fatigue in bridge decks, each detail shall satisfy the following: ( + 0.1)CLfsr  Fsr where fsr = calculated fatigue stress range at the detail due to passage of a tandem set of 125 kN axles spaced 1.2 m apart and with a transverse wheel spacing of 1.8 m, MPa

17.20.2.3 Design criteria for pedestrian and wind loading Care should be taken in the design of structures subjected to cyclic pedestrian- or wind-induced loading, to ensure that this loading does not result in failure of the structure under the fatigue limit state. An effort should be made to ensure that this loading does not occur at resonant frequencies, which can result in significant amplification of the stress ranges induced by these loading sources.

17.20.2.4 Fatigue stress range resistance of a member or detail The fatigue stress range resistance of a member or a detail, Fsr , shall be calculated as follows: Fsr = (/Nc)1/m Fsrt/2

but not greater than (/105)1/m

where m = fatigue life constant given in Table 17.5 for the selected detail  = fatigue life constant pertaining to the detail category established in accordance with Clause 17.20.2.5 and specified in Table 17.5 Nc = 365yNd(ADTTf) where y = design life (typically 75 years unless otherwise specified by the Owner or Engineer) = number of design stress cycles experienced for each passage of the design truck, as specified Nd in Table 17.6 ADTTf = single-lane average daily truck traffic, as obtained from site-specific traffic forecasts. In lieu of such data, ADTTf shall be estimated as p (ADTT), where p shall be 1.0, 0.85, or 0.80 for the cases of one, two, or three or more lanes available to trucks, respectively, and ADTT shall be as specified in Table 17.7

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Table 17.5 Fatigue life constants and constant amplitude threshold stress ranges (See Clauses 17.20.2.2.1 and 17.20.2.4.)

Detail category

Fatigue life constant, 

Fatigue life constant, m

Constant amplitude threshold stress range, Fsrt, MPa

Damage equivalence factor, 

A

21.7 × 1018

6.85

70.0

0.65

B

199 × 1012

4.84

37.2

0.60

C

894 × 109

3.64

27.7

0.55

D

206 × 109

3.73

17.3

0.55

E

31.1 × 109

3.45

12.6

0.54

Table 17.6 Values of Nd (See Clause 17.20.2.4.)

Longitudinal members

Span length, L,  12 m

Span length, L, < 12 m

Simple-span girders

1.0

2.0

Near interior support (within 0.1L on either side)

1.5

2.0

All other locations

1.0

2.0

Cantilever girders

5.0

5.0

Trusses

1.0

1.0

Transverse members

Spacing  6 m

Spacing < 6 m

All cases

1

2

Continuous girders

Table 17.7 Average daily truck traffic (See Clause 17.20.2.4.)

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Class of highway

ADTT

A

4000

B

1000

C

250

D

50

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17.20.2.5 Detail categories The detail categories shall be as specified in Table 17.8. The following details shall be prohibited for use when cyclic loading is present: (a) partial penetration groove welds; (b) cover plates attached to girder flanges using only fillet welds that are oriented transversely with respect to the direction of stress in the member; (c) intermittent fillet welds; and (d) permanent backing transverse to the direction of computed stress.

17.20.2.6 Width-to-thickness ratios of transversely stiffened webs The width-to-thickness ratios of transversely stiffened webs, h/w, shall not exceed E/(67 Fy ) unless a longitudinal stiffener is provided in accordance with Clause 17.12.4.3.

17.20.3 Distortion-induced fatigue 17.20.3.1 General When members designed in accordance with Clause 17.20.2 for load-induced fatigue are provided with interconnection components such as diaphragms, cross-bracing, and lateral bracing, both the members and the interconnection components shall be examined for distortion-induced fatigue. Wherever practicable, elements of the primary member shall be fastened to the interconnection member unless otherwise Approved. The requirements for controlling web buckling and flexing of girder webs specified in Clause 17.20.3.2.2 shall apply.

17.20.3.2 Connection of diaphragms, cross-frames, lateral bracing, and floor beams 17.20.3.2.1 Connection to transverse elements Unless otherwise Approved, the connections of diaphragms, including internal diaphragms, cross-frames, lateral bracing, floor beams, etc., to main members shall be made using transverse connection plates that are welded or bolted to both the tension and compression flanges of the main member. If transverse stiffeners of the main members form part of the connection, they shall be similarly connected. In straight non-skewed bridges, the connections shall be designed to resist a factored horizontal force of 90 kN unless a more exact value is determined by analysis.

17.20.3.2.2 Connection to lateral elements If connections of diaphragms, including internal diaphragms, cross-frames, lateral bracing, floor beams, etc., are to be made to elements that are parallel to the longitudinal axis of the main member, the lateral connection plates shall be attached to both the tension and compression flanges of the main member.

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Table 17.8 Detail categories for load-induced fatigue (See Clauses 17.20.2.1 and 17.20.2.5.)

General condition

Situation

Plain members

Base metal With rolled or cleaned surfaces. Edges with a surface roughness not exceeding 25 µm.

Built-up members

Base metal and weld metal in components, without attachments, connected by one of the following: (a) continuous full-penetration groove welds with backing bars removed; (b) continuous fillet welds parallel to the direction of applied stress; (c) continuous full-penetration groove welds with backing bars in place; (d) base metal at ends of partial-length cover plates (with or without end welds); or (e) weld metal (fillet weld ends).

Detail category

Illustrative example (see Figure 17.4) 1, 2

A 3, 4, 5, 7 B B B E

7

E

Groove-welded splice connections with weld soundness established by non-destructive testing and all required grinding in the direction of the applied stresses

Base metal and weld metal at full-penetration groove-welded splices, as follows: (a) of plates of similar cross-sections with welds ground flush; B (b) with transitions in width or thickness (with welds ground B to provide slopes not steeper than 1.0 to 2.5); and (c) with or without transitions with slopes not greater than C 1.0 to 2.5, when weld reinforcement is not removed.

Longitudinally loaded groove-welded attachments

Base metal at details attached by full penetration groove welds, as follows: (a) when the detail length in the direction of applied stress is (i) less than 50 mm; (ii) between 50 mm and 12 times the detail thickness, but less than 100 mm; or (iii) greater than either 12 times the detail thickness or 100 mm; (b) with a transition radius, R, with the ends of welds ground smooth, regardless of detail length: (i) R  600 mm; (ii) 600 mm > R  150 mm; or (iii) 150 mm > R  50 mm; or (c) with a transition radius, R, with ends of welds not ground smooth.

8, 9 10, 10A 8, 9, 10, 10A

C D

6, 18 18

E

18 12

B C D E

12 (Continued)

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Table 17.8 (Continued)

General condition

Situation

Transversely loaded groove-welded attachments with weld soundness established by non-destructive testing and all required grinding transverse to the direction of stress

Base metal at detail attached by full-penetration groove welds with a transition radius, R, as follows: (a) to flange, with equal plate thickness and weld reinforcement removed: (i) R  600 mm; (ii) 600 mm > R  150 mm; (iii) 150 mm > R  50 mm; or (iv) R < 50 mm; (b) to flange, with equal plate thickness and weld reinforcement not removed or to web: (i) R  150 mm; (ii) 150 mm > R  50 mm; or (iii) R < 50 mm; (c) to flange, with unequal plate thickness and weld reinforcement removed: (i) R  50 mm; or (ii) R < 50 mm.

Fillet-welded connections with welds normal to the direction of stress

Base metal, as follows: (a) at details other than transverse stiffener to flange or transverse stiffener to web connections; and (b) at the toe of transverse stiffener to flange and transverse stiffener to web welds.

Fillet-welded connections with welds normal and/or parallel to the direction of stress

Shear stress on the weld throat

Longitudinally loaded fillet-welded attachments

Base metal at details attached by fillet welds, as follows: (a) when the detail length in the direction of applied stress is (i) less than 50 mm; (ii) between 50 mm and 12 times the detail thickness, but less than 100 mm; or (iii) greater than either 12 times the detail thickness or 100 mm: (1) detail thickness < 25 mm; or (2) detail thickness  25 mm; and (b) with a transition radius, R, with the ends of welds ground smooth, regardless of detail length: (i) R  50 mm; or (ii) R < 50 mm.

Transversely loaded fillet-welded attachments with welds parallel to the direction of primary stress

Base metal at details attached by fillet welds

Detail category

Illustrative example (see Figure 17.4) 12

B C D E C D E D E E

19

C

6

E

16

C D

13, 15,18, 20 18, 20 7, 16, 18, 20

E E 12 D E E

12

(Continued)

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Table 17.8 (Concluded)

General condition

Situation

Mechanically fastened connections

Base metal at the gross section of slip-critical connections and

ASTM A 325 and ASTM A 325M bolts

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at the net section of bearing connections, where the joint configuration does not result in out-of-plane bending in the connected material and the stress ratio (the ratio of minimum stress to maximum stress), as follows: (a) stress ratio  0; (b) 0 < stress ratio < 0.5; or (c) 0.5  stress ratio. Base metal at the gross section of slip-critical connections and at the net section of bearing connections, where the joint configuration results in out-of-plane bending in connected material. See Clause 10.17.2.6

Detail category

Illustrative example (see Figure 17.4) 17a

B D E E

17b

—

—

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Example 2

Example 1

CJP

CJP

or

Example 4

Example 3

CJP or

Gusset

Example 5

Example 6

Figure 17.4 Detail categories for load-induced fatigue (See Table 17.8.) (Continued)

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End weld optional

CJP

Example 8

Example 7

CJP CJP

CJP

Example 10 Example 9

CJP CJP

R = 600 mm

Example 10A

Example 11 (detail category not established for aluminum)

Figure 17.4 (Continued)

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CJP L R CJP

or

Example 13

R

Example 12 L

Example 14 of CAN/CSA-S16 not used for bridges Example 15

L > 100 mm

Example 17a

Example 16

Example 17b

Figure 17.4 (Continued)

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L L

CJP or CJP or

Example 18

Example 19

L

Example 20

Example 21

Category B Example 21 (detail category not established for aluminum)

End of weld

Example 22 (detail category not established for aluminum)

Example 22

Figure 17.4 (Concluded)

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17.20.4 Bridge decks Distortion-induced fatigue shall be minimized through appropriate detailing in accordance with Clause 17.20.3. The stress ranges for live-load-induced fatigue shall be as specified in Clause 17.20.2.

17.21 Fracture control 17.21.1 General Fracture control shall be considered in the material selection and structural design.

17.21.2 Identification Fracture-critical members and primary tension members shall be clearly identified on the Plans. Shop drawings shall identify the extent of these members.

17.22 Splices and connections 17.22.1 General Note: This Clause covers the design of splices and connections made by using bolts or by welding.

17.22.1.1 General design considerations Splices and connections shall be designed at the ULS for the larger of (a) the calculated forces at the splice or connection; or (b) 75% of the factored resistance of the member, such resistance to be based on the condition of tension, compression, bending, or shear that governed selection of the member. Except for handrails and non-load-carrying components, connections shall contain at least two 16 mm diameter bolts or equivalent welds. For pedestrian bridge structures, where joints and assemblies cannot meet the minimum requirements, the adequacy of joints and assemblies shall be demonstrated by testing, in accordance with Clause 13 of CSA S157.

17.22.1.2 Alignment of axially loaded members When the centroidal axes of axially loaded members meeting at a joint do not intersect at a common point, the effect of joint eccentricity shall be considered.

17.22.1.3 Proportioning of splices and connections Splices and connections shall be designed for all of the forces, including axial, bending, and shear forces, that can occur in the connected components (allowing for any eccentricity of loading). Where the fatigue requirements of Clause 17.20 govern the design, the connections shall be designed to the same requirements.

17.22.1.4 Compression members finished to bear At the ends of compression members that are finished to bear, splice material and connecting bolts or welds shall be arranged to hold all of the components in place and shall be proportioned to resist not less than 50% of the force effects at the ULS.

17.22.1.5 Beam and girder connections End connections for beams and girders that are proportioned to resist vertical reactions only shall be detailed to minimize the flexural end restraint, except that inelastic action in the connection at the SLS may be used in order to accommodate the end rotations of unrestrained simple beams. The connections of beams and girders subject to both reaction shear and end moment due to rigid, continuous, or cantilever construction shall be proportioned for the loads at the ULS. Axial forces, if present, shall also be considered.

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17.22.1.6 Sharing of loads Loads shall not be shared between mechanical fasteners and welds in the same direction.

17.22.2 Bolted connections 17.22.2.1 General The mechanical fasteners including lockbolts that may be used for connections between aluminum members shall comply with Clause 17.4.4. The bearing areas under the head and collar of lockbolts shall not be less than those of conventional bolts and nuts.

17.22.2.2 Bolts in tension 17.22.2.2.1 Tensile resistance at the ultimate limit states The factored tensile resistance, Tr , developed by the bolts in a bolted joint subjected to tension, Tf , shall be taken as the lesser of (a) Tr = 0.75f n Ab Fu; or (b) Tr = f n Ab Fy where n = number of bolts Ab = cross-sectional area of a bolt based on nominal diameter, mm2 Bolts in tension shall be proportioned to resist the factored tensile force, Tf , taken as the sum of the factored external load and any additional tension resulting from prying action produced by the deformations of the connected parts, but neglecting bolt pretension.

17.22.2.2.2 Tensile resistance at the fatigue limit state High-strength steel bolts subjected to tensile cyclic loading shall comply with Clause 10.17.2.6.

17.22.2.3 Shear resistance at the ultimate limit states The factored shear resistance of bolts, Vr , in a bolted joint subjected to a shear force, Vf , shall be taken as Vr = 0.60f n m Ab Fu where m = number of shear planes Fu = ultimate strength of the bolt material, MPa If any bolt threads are intercepted by a shear plane, the factored shear resistance of the joint shall be taken as 0.7Vr .

17.22.2.4 Slip-critical joints 17.22.2.4.1 General Bolted joints required to resist shear between the connected parts shall be designed as slip-critical connections unless otherwise Approved. Bolts used in slip-critical joints shall comply with ASTM A325M and be zinc-coated.

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17.22.2.4.2 Slip resistance at the serviceability limit states If preloaded high-strength steel bolts with controlled tightening are to be used to develop shear resistance at the joint by friction, the surface shall be prepared by sand blasting or other equivalent treatment to ensure that a coefficient of friction of at least 0.3 is available. Installation of the bolts shall be in accordance with Clause 17.25.5. The slip resistance, Vs , of a bolted joint in a slip-critical connection subjected to shear at the SLS, V, shall be taken as Vs = 0.15 n m Ab Fu A slip-critical connection shall also satisfy the shear and bearing criteria at the ULS.

17.22.2.5 Bolts in shear and tension 17.22.2.5.1 Resistance at the serviceability limit states Bolts in a connection subjected to loads that cause shear, V, and tension, T, shall satisfy the following:

V 1.9T + ≤ 1.0 Vs n Ab Fu The requirements of Clause 17.22.2.4.2 shall also be met.

17.22.2.5.2 Resistance at the ultimate limit states A bolt that is required to resist a tensile force and a shear force at the ULS shall satisfy the following: 2

2

⎛ Vf ⎞ ⎛ Tf ⎞ ⎜⎝ V ⎟⎠ + ⎜⎝ T ⎟⎠ ≤ 1.0 r r

17.22.2.6 Bolts in bearing 17.22.2.6.1 Bearing resistance at the ultimate limit states The factored bearing resistance, Br , of the connected material for each loaded bolt shall be taken as the lesser of (a) Br = u e t Fu: or (b) Br = u 2 d t Fu where e = perpendicular distance from the hole centre to the end edge in the direction of the loading (not less than 1.5d), mm t = plate thickness, mm d = fastener diameter, mm

17.22.2.6.2 Lap joints For unrestrained lap joints in tension, the factored bearing resistance, Br , shall be taken as the lesser of

(a) Br =

fu (t1 + t2 )e Fu ; or 4

(b) Br =

fu (t1 + t2 )d Fu ≤ fu 2 d t1 Fu 2

where t1, t2 = thickness of the plates, t1 < t2, mm

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17.22.2.6.3 Oblique end edges Where the end edge is oblique to the line of the tension force (see Figure C17.31 in the Commentary), the factored bearing resistance, Br , for a single bolt shall be taken as the lesser of (a) Br = u [e + (e – d) cos2 ] t Fu ; or (b) Br = u 2 d t Fu. where  = angle made by the end edge with the direction of the force (when  approaches zero degree, d becomes do )

17.22.2.7 Tear-out of bolt groups (block shear) The tear-out of bolted joint consists of tension failure or a combination of tension and shear failure along the planes of rupture. Calculations for the tear-out resistance of the bolted groups shall take account of all the possible planes of failure in tension and shear. The effective net cross sectional area of tear-out planes shall be determined in accordance with Clause 17.8.2.2.

17.22.2.8 Tear-out of bolt groups subjected to torque For a group of three or more equally spaced bolts that lie on a circle (see Figure C17.32 in the Commentary) designed to resist a torque, Qf , Clause 17.22.2.9 shall apply but, additionally, the torque shall not exceed Qr = u 0.5 n R (s – do) t Fu where R = radius of the circle measured to the centre of the holes, mm s = centre-to-centre distance between adjacent bolts on the circle, mm

17.22.2.9 Eccentrically loaded bolt groups 17.22.2.9.1 Highest bolt force (elastic)

For a group of equal strength bolts subjected to a factored load, Pf , applied at an eccentricity, e, from the centroid of the bolt group (see Figure C17.33 in the Commentary), the procedure shall be as follows: (a) Determine the position of the centroid of the bolt group. (b) Determine the normal distance, e, from the centroid to the line of action of the applied force. (c) Determine the distance, c, from the centroid to the centre about which the bolt group rotates under the action of the eccentric load. This distance is measured along the line through the centroid of the bolt group perpendicular to the line of action of the applied force, on the side opposite to that of the applied force, and shall be taken as

xi2 + y i2 ) ( ∑ c= ne

where xi = x-coordinate of the i th bolt relative to the centroid, mm yi = y-coordinate of the i th bolt relative to the centroid, mm e = eccentricity of the applied load from the centroid of a bolt group, mm (d) The highest factored force, Rf , on a bolt shall be taken as

Rf =

Pf dm nc

where dm = distance from centre of rotation to the farthest bolt, mm c = distance between the centroid to the centre of rotation of a bolt group, mm

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17.22.2.9.2 Factored resistance (fully plastic) The centre of rotation shall be determined in accordance with Clause 17.22.2.9.1. If the calculated centre of rotation falls near a bolt, the location of the bolt may be taken to be the centre of rotation. The limiting factored applied load, Pr , shall be taken as

Pr = Rr

( ∑ di ) (e + c )

where Rr = factored resistance of each bolt, N di = distance from the i th bolt to the centre of rotation, mm

17.22.2.10 Detailing of bolted connections 17.22.2.10.1 Contact of bolted parts Bolted parts shall fit together solidly when assembled and shall not be separated by gaskets or any other interposed compressible material.

17.22.2.10.2 Hole size The nominal diameter of a hole shall not be more than the nominal bolt size by 1 mm for bolt diameters up to 12 mm and 1.5 mm for larger diameters.

17.22.2.10.3 Surface treatment The faying surfaces of slip-critical connections shall be prepared by sand blasting or other equivalent treatment.

17.22.2.10.4 Maximum number of bolts Lines of bolts connecting axially loaded members shall not exceed 6 in number or 15d in extension, where d is the nominal bolt diameter, without a demonstration that the anticipated strength will be realized.

17.22.2.10.5 Bolt spacing The minimum distance between centres of bolt holes shall be not less than 2.5 times bolt diameters. The maximum bolt spacing shall be governed by the requirements for sealing or stitching specified in Clauses 17.22.2.10.6 to 17.22.2.10.8.

17.22.2.10.6 Sealing bolts For sealing bolts, the pitch, p, between bolts on a single line adjacent to a free edge of an outside plate or shape shall be equal to or less than (75 + 3t) 125 When a second line of bolts is uniformly staggered with those in the line adjacent to the free edge, at a gauge less than (25 + 3t) therefrom, the staggered pitch, p, in two such lines considered together shall be equal to or less than

⎛ 3g ⎞ 75 + 3t − ⎜ ⎟ ≤ 125 ⎝ 4⎠ where t = thickness of thinner outside plate or shape, mm g = transverse spacing between fastener gauge lines, mm or one-half the requirement for a single line, whichever is greater.

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17.22.2.10.7 Stitch bolts Unless closer spacing is required for transfer of load or for sealing inaccessible surfaces, the longitudinal spacing in-line between intermediate bolts in built-up compression members shall not exceed 8.5t. The gauge, g, between adjacent lines of bolts shall not exceed 17t. The staggered pitch, p, between two adjacent lines of staggered holes shall not exceed

⎡ 3g ⎤ 10t − ⎢ ⎥ ≤ 8.5t ⎣8⎦ The pitch for tension members shall not exceed twice that specified for compression members. The gauge for tension members shall not exceed 17t.

17.22.2.10.8 Stitch bolts at the ends of compression members All component parts that are in contact with one another at the ends of built-up compression members shall be connected by bolts spaced longitudinally not more than 8.5t where t is the thickness of thinner outside plate. The factored compressive resistance in the direction of stress may be controlled by local buckling of the plate between bolts and shall not be greater than the resistance determined by treating outside plates and shapes as columns having a length equal to the pitch of the bolts.

17.22.2.10.9 Minimum edge distance The minimum edge distance from the centre of a bolt hole to the edge parallel to the direction of loading shall not be less than 1.25 times the bolt diameter.

17.22.2.10.10 Minimum end distance The minimum end distance from the centre of a bolt hole to the end edge perpendicular to the direction of loading shall not be less than 1.5 times the bolt diameter.

17.22.2.10.11 Maximum edge or end distance The maximum distance from the centre of a bolt to the nearest edge of connected components shall be the lesser of 5.5 times the thickness of the outside connected component and 90 mm.

17.22.2.10.12 Sloping surfaces Bevelled washers shall be used under the head or nut when the two bearing surfaces are not parallel.

17.22.2.10.13 Washers Washers shall always be used under the bolt head and the nut.

17.22.3 Welded connections 17.22.3.1 General Welding design shall comply with CSA W59.2. In the design of welded joints, consideration should be given both to the strength of the welds and to the strength of the HAZ. The filler alloy shall be as specified in Table 17.9 or otherwise approved. The mechanical properties for weld metal are given in Table 17.3.

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Table 17.9 Aluminum alloy filler metals for structural welding of various base aluminum alloys (See Clause 17.22.3.1.) Base metal to base metal

5052

5083

5086

6005A, 6061, 6063, 6082

354.0, C355.0

366.0, A356.0, A357.0

356.0, A356.0, A357

4043

5356

5356

4043

4145

4043

354.0, C355.0

4043

NR

NR

4145

4145

—

6005A, 6061, 6063, 6082

4043, 5356

5356

5356

4043, 5356

—

—

5086

5356

5356

5356

—

—

—

5083

5356

5183, 5556

—

—

—

—

5052

5356

—

—

—

—

—

NR = Not recommended Notes: (1) The filler alloy shown is the best choice for most structural applications. Where two filler alloys are shown, either is acceptable. (2) Whenever 4043 is shown, 4047 may be used as an alternative. (3) Whenever 5356 is shown, 5183 or 5556 may be used as an alternative.

17.22.3.2 Groove welds 17.22.3.2.1 Partial Penetration Partial penetration groove welds shall not be allowed for joints carrying calculated forces.

17.22.3.2.2 Tension The factored tensile resistance, Tr , of a member containing a full penetration groove weld shall be the least of the values taken as the formulas in Clauses 17.10.3(a), (c), and (d).

17.22.3.2.3 Compression normal to the weld axis The factored compressive resistance, Cr , of a full penetration transverse groove weld that is fully constrained against buckling shall be the lesser of the values taken as the following formulas: (a) Cr = y A Fy ; and (b) Cr = u A Fwu.

17.22.3.2.4 Shear The factored shear resistance, Vr , of a full penetration groove weld shall be the least of the values taken as the following formulas: (a) Vr = y 0.6 A Fy ; and (b) Vr = u 0.6 A Fwu.

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17.22.3.3 Fillet welds 17.22.3.3.1 Concentrically loaded fillet welds The factored resistance per unit length, vr , of a concentrically loaded fillet weld shall be taken as the formula vr = f k tw Fwu For forces applied at an inclination to the weld direction, the components vx, vy , and vz of the factored force per unit length shall be such that 2

2 2 ⎛ vy ⎞ 2 ⎛ vx ⎞ ⎛ vz ⎞ + + ⎜⎝ ⎟ ≤ (ff tw Fwu ) ⎜⎝ ⎟ ⎜⎝ 0.7 ⎟⎠ 0.6 ⎠ 0.7 ⎠

where k

= a factor related to the direction of the applied force (see Figure C17.34 in the Commentary) = 0.6 for direction x, along the axis of the fillet weld, i.e., in simple shear = 0.7 for direction y, perpendicular to the plate to which the connection is made = 0.7 for direction z, perpendicular to weld in the plane of the plate

tw = weld throat (distance through a fillet weld, usually taken as D/ 2 ) where D = fillet weld, mm

17.22.3.3.2 Effective length of fillet welds The effective length, Lm, of an intermittent fillet weld shall be taken as Lm = L – 2 t w where L = the actual length of the fillet weld, mm

17.22.3.3.3 Eccentrically loaded fillet welds 17.22.3.3.3.1 Moment in the X-Z plane For welds subjected to a factored eccentric load, Pf , in the X-Z plane [see Figure C17.35(a) in the Commentary], the procedure to determine the resistance shall be as follows: (a) In order to establish the maximum force per unit length, vf , in the weld, in the elastic range (to be used, for example, when predicting fatigue life), the procedure shall be as follows: (i) Determine the position of the centroid of the weld pattern. (ii) Determine the perpendicular distance, e, from the centroid to the line of action of the applied force. (iii) Determine the total length, H, of the median line of the weld. (iv) Calculate the polar moment of inertia, Ip = Ix + Iy , of the weld pattern about the centroid, using a constant weld throat, tw. (v) Determine the distance from the centroid to the centre about which the weld rotates under the action of the eccentric load. This distance, c, is measured along the line through the centroid of the fastener group perpendicular to the line of action of the applied force, on the side opposite to that of the applied force, and is taken as

c=

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where

Ip

rp =

H tw

where H tw = total throat area of the weld (vi) The maximum force per unit length, vf , in the elastic range, shall then be given by

vf =

Pf dm Hc

where dm = the distance from the centre of rotation to the farthest point of the weld, mm (b) In order to establish the factored resistance, Pr , the procedure shall be as follows: (i) Use the procedure in Item (a) to determine the centre of rotation. (ii) Divide the weld into convenient straight elements on each side of the line passing through the centre of rotation and the centroid. (iii) Determine the distances, di , from the centre of rotation to the midpoints of the elements. (iv) Determine the factored resistance, Pr , by

Pr =

∑ (Li

di v r )

e +c

where Li = length of the i th element, mm vr = the factored resistance per unit length of the weld, obtained in Clause 17.22.3.3.1 using k = 0.6, N/mm

17.22.3.3.3.2 Moment in the X-Y plane For double fillet welds subjected to eccentric loading in the X-Y plane (see Figure C17.35(b) in the Commentary), the weld shall be continued around the edges of the plate. The factored resistance, Pr , shall be taken as

Pr =

ncr ntr L2 ≤ nsr L 2e (ncr + ntr )

where L = length of weld (plate length), mm ncr = factored compressive resistance per unit length of the welded plate, N/mm, taken as the lesser of the following values: (a) u t Fwu ; or (b) y t Fy ntr = factored tensile resistance per unit length of the welded joint; N/mm, taken as the least of the following values: (a) u t Fwu ; (b) r t Fy ; or (c) f tw k’ Fwu where

⎛n ⎞ k ′ = 1.4 1 − ⎜ x ⎟ ⎝ nsr ⎠

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where nx = shear force per unit length of the welded joint = Pr /L, N/mm nsr = factored shear resistance per unit length of the welded joint, N/mm, taken as the least of the following values: (a) u t (0.6 Fwu); (b) y t (0.6 Fy); or (c) f 2 tw (0.6 Fwu) The value of k’ is determined by trial and error, as the value of nx is not known initially. In general design, when the influence of the shear force is small, and the fillet weld controls the strength, the factored moment resistance, Mr, may be taken as

⎛ t L2 ⎞ Mr = ff ⎜ w ⎟ Fwu ⎝ 3 ⎠

17.22.3.3.3.3 Moment in the Y-Z plane For double fillet welds bending in the Y-Z plane (see Figure C17.35(c) in the Commentary), the factored resistance, Mr , shall be taken as Mr = f 0.7 tw L (t + 0.7 tw ) Fwu Single fillet welds shall not be subjected to calculated bending forces in the Y-Z plane.

17.22.3.3.4 Flare groove welds Where welds are to be made between rounded surfaces, as between round bars and at the corners of formed shapes, the procedures used shall have been demonstrated to give the required penetration and throat thickness. Compliance with the requirements may be done by measurement of the weld throat or by load tests. If measurement is made, the throat shall exceed that required for the design strength by 3 mm. If tests are made, there shall be at least three specimens made consecutively using the same procedure. The lowest value obtained shall be used as the characteristic strength.

17.22.3.3.5 Slot and plug welds A connection may be made by a fillet weld along the inside edge of a hole or slot if the radii of the corners are not less than the thickness of the plate plus 5 mm. The weld shall extend around the full length of the inside edge of the hole. The length of the weld shall be taken as the length of the centroidal axis of the fillet. Holes and slots completely filled with weld metal shall not be used to carry calculated forces.

17.22.3.4 HAZ softening adjacent to welds 17.22.3.4.1 General In the design of welded structures using work hardened or heat treated alloys, the reduction in strength properties that occurs in the vicinity of welds shall be allowed for. Exceptions to this rule, where there is no weakening adjacent to welds, occur in alloys in the O condition; or if the material is in the F condition and design strength is based on O-condition properties. For design purposes, it is assumed that throughout the HAZ, the strength properties are reduced at a constant level.

17.22.3.4.2 Severity of softening The characteristic value of the yield strength, Fwy , and the ultimate strength, Fwu , in the HAZ are listed in Table 17.3 for some common alloys.

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17.22.3.4.3 Extent of HAZ The HAZ is assumed to extend a distance bhaz in any direction from a weld, measured as follows (see Figure 17.5): (a) transversely from the centre line of an in-line butt weld; (b) transversely from the point of intersection of the welded surfaces at fillet welds; (c) transversely from the point of intersection of the welded surfaces at butt welds used in corner, tee, or cruciform joints; and (d) in any radial direction from the end of a weld. The HAZ boundaries shall be taken as straight lines normal to the metal surface, particularly if welding thin material. However, if surface welding is applied to thick material, it is permissible to assume a curved boundary of radius bhaz , as shown in Figure 17.5.

bhaz

bhaz

bhaz bhaz

bhaz

bhaz

bhaz

bhaz

bhaz bhaz

bhaz

bhaz

bhaz

bhaz

bhaz

bhaz

bhaz

bhaz

*

bhaz bhaz

*If this distance is less than 3bhaz , assume that the HAZ extends to the full width of outstand.

Figure 17.5 The extent of heat-affected-zones (HAZ) (See Clause 17.22.3.4.3.) For a metal inert gas (MIG) weld laid on unheated material, and with interpass cooling to 60 °C or less when multi-pass welds are laid, values of bhaz shall be as follows: t  6 mm

bhaz = 20 mm

6 < t  12 mm

bhaz = 30 mm

12 < t  25 mm

bhaz = 35 mm

t > 25 mm

bhaz = 40 mm

The boundaries in Figure 17.5 apply to in-line butt welds (two valid heat paths) or to fillet welds at T-junctions (three valid heat paths) in 6000 and 5000 series. If the junctions between cross-section parts are fillet welded, but have more than three heat paths, the value of bhaz shall be multiplied by 3/n, where n is the number of heat paths.

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For a tungsten insert gas (TIG) weld, the extent of the HAZ is greater because the heat input is greater than for a MIG weld. TIG welds for in-line butt or fillet welds in 6000 and 5000 series alloys shall have a value of bhaz taken as t  6 mm: bhaz = 30 mm If two or more welds are close to each other, their HAZ boundaries overlap. A single HAZ then exists for the entire group of welds. When a weld is located too close to the free edge of an outstand, the dispersal of heat is less effective. This applies when the distance from the edge of the weld to the free edge is less than 3bhaz . In these circumstances, it shall be assumed that the entire width of the outstand is affected by the heat of the weld (see Figure 17.5). If the cross-section parts to be joined by welds do not have a common thickness t, it is conservative to assume in all the above expressions that t is the average thickness of all parts. This shall apply as long as the average thickness does not exceed 1.5 times the smallest thickness. For greater variations of thickness, the extent of the HAZ should be determined from hardness tests on specimens.

17.22.4 Gusset plate connections For connections made by bolts or welds with gusset plates, the tensile resistance (including block tearout) and the compressive resistance of gusset plates shall be assessed as appropriate. The factored shear resistance, Vr , of the gusset plate shall be taken as the lesser of (a) Vr = 0.50u Ag Fy on the gross section; or (b) Vr = 0.50u An Fu on the net section where An = minimum cross-sectional area subjected to shear, allowing for holes, if present, mm2 The unsupported edge of a gusset plate shall be stiffened if its length exceeds 545/ Fy times its thickness.

17.23 Anchors Steel anchors shall be designed in accordance with Section 10.

17.24 Pins, rollers, and rockers 17.24.1 Bearing resistance The factored bearing resistance, Br , developed by a component or portion of a component subjected to bearing shall be calculated as follows: (a) on the contact area of machined, accurately sawn, or fitted parts and on the bearing area of pins, as follows: Br = 1.50y Fy A where the bearing area of pins is taken as the pin diameter multiplied by the thickness of the connected parts; and (b) on expansion rollers or rockers, as follows:

⎤ ⎡ ⎢ R ⎥ Br = 0.00026 fy ⎢ 1 ⎥ L Fy2 ⎢ 1 − R1 ⎥ ⎢⎣ R2 ⎥⎦ where R1, R2 = radius of roller or rocker and of groove of supporting plate, respectively, mm L

= length of roller or rocker, mm

Fy

= specified minimum yield stress of the weaker part in contact, MPa

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17.24.2 Pins 17.24.2.1 Bending resistance The factored bending resistance of a pin shall be taken as Mr = y SFy

17.24.2.2 Shear resistance The factored shear resistance of a pin shall be taken as Vr = 0.60y AFy

17.24.2.3 Combined bending and shear Sections of pins subject to both bending and shear shall be proportioned so that 3

Mf ⎛ Vf ⎞ + ≤ 1.0 Mr ⎜⎝ Vr ⎟⎠

17.24.2.4 Pin connection details Pins shall be of sufficient length to ensure full bearing of all parts connected to the turned body of the pin. They shall be secured in position by hexagonal recessed nuts or by hexagonal solid nuts with washers or, if the pins are bored, by throughrods with recessed cap washers. Pin nuts shall be malleable steel castings and shall be secured by cotter pins in the screw ends. Components shall be held against lateral movement on pins. The location of pins with respect to the centroidal axes of components shall be such as to minimize stresses due to bending. Pin plates shall have a width commensurate with the dimension of the member. Their length, measured from pin centre to end, shall be at least equal to their width. Pin plates shall contain sufficient fasteners to distribute their due portion of the pin load to the full cross-section of the component. Only fasteners located in front of two lines drawn from the centre of the pin toward the body of the components and inclined at 45° on either side of the axis of the component shall be considered effective for this purpose. For welded H-shapes, pin plates shall be provided on both flanges and shear lag effects shall be considered.

17.25 Construction requirements 17.25.1 Submissions 17.25.1.1 General Erection diagrams, shop details, welding procedures, camber method, and erection procedure drawings and calculations shall be submitted to the Owner. Primary tension and fracture-critical members shall be identified on the plans in accordance with Clause 17.21.2. This requirement shall be stipulated on the Plans.

17.25.1.2 Erection diagrams Erection diagrams are general-arrangement drawings showing or indicating the principal dimensions of the bridge, piece marks, the sizes of all members, field welding requirements, the sizes and types of bolts, and bolt installation requirements.

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17.25.1.3 Shop details Shop details shall provide (a) full detail dimensions and sizes of all component parts of the structure. These dimensions shall make allowance for changes in shape due to weld shrinkage, camber, and any other effects that cause finished dimensions to differ from initial dimensions; (b) all necessary specifications for the materials to be used; (c) identification of areas requiring special surface treatment; (d) identification of fracture-critical and primary tension members and component parts; (e) bolt installation requirements; and (f) details of all welds.

17.25.1.4 Welding procedures Welding procedures shall comply with CSA W47.2.

17.25.1.5 Erection procedure drawings and calculations The erection procedure drawings and calculations shall fully indicate the proposed method of erection, including the sequence of erection, the weights and lifting points of the members, and the location and lifting capacities of the cranes used to lift them. Details of temporary bracing and bents to be used during construction shall be shown. Calculations shall be provided to show that members and supports are not overloaded during erection.

17.25.1.6 Symbols for welding and non-destructive testing The symbols for welding and non-destructive testing on shop drawings shall be in accordance with CSA W59.2.

17.25.2 Materials 17.25.2.1 Aluminum Substitution of aluminum members or components for size and alloy shall not be permitted unless Approved. All aluminum shall be new. Acceptance of any material by an inspector shall not preclude subsequent rejection of the material if it is found defective.

17.25.2.2 Bolts, nuts, and washers Zinc-coated nuts and bolts shall be shipped together as an assembly. The nuts of coated or plated fasteners shall be over-tapped by the minimum amount required for assembly and shall be lubricated with a lubricant containing a visible dye. The use of a mechanically deposited zinc coating shall require Approval.

17.25.2.3 Electrodes The supply and storage of filler shall comply with CSA W59.2.

17.25.3 Fabrication 17.25.3.1 Quality of work The standards for quality of work and finish shall comply with the best modern practices for metal bridge fabrication (with particular attention to the appearance of parts exposed to view).

17.25.3.2 Storage of materials Plain or fabricated structural aluminum shall be stored above the ground on skids or other supports and kept free from dirt and other foreign matter or exposed to moisture. Long members shall be adequately supported to prevent excessive deflection. Aluminum members shall not be stored in contact with one another if exposed to moisture.

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17.25.3.3 Plates and extruded members 17.25.3.3.1 Edges Material thicker than 12 mm shall not be sheared. When arc cutting is used in cases where fatigue resistance is important, at least 1 mm shall be mechanically removed from the edges. Gas or flame cutting shall not be used. If re-entrant cuts are used, they shall be filleted by drilling prior to cutting. In addition, CSA W59.2 shall apply to edge preparation of components to be welded.

17.25.3.3.2 Camber Members shall be formed to the prescribed camber with allowance for distortion due to fabrication.

17.25.3.3.3 Forming In general, forming of aluminum shall be carried out at room temperature. Should hot forming be unavoidable, the procedures shall conform to the requirements of CSA W59.2 and the post-forming mechanical properties shall be checked using hardness tests. Bends shall be smooth, without sharp kinks. Cracks shall be cause for rejection. Table 17.10 should be used as a guide for recommended minimum bend radii for 90° cold forming.

17.25.3.4 Bolt holes Holes for bolted joints not subject to fatigue may be punched to the finished size in material 12 mm or less in thickness. Material greater than 12 mm thick shall not be punched to finished size, but may be punched under size and reamed to size. The hole size shall comply with Clause 17.22.2.10.2. Joints designed for rigidity under service loads or for fatigue conditions shall be slip critical joints. Holes for bolted joints in fatigue service shall be drilled or punched under size and reamed.

17.25.3.5 Pins and rollers Pins and rollers shall be accurately turned to the dimensions and finish shown on the drawings and shall be straight and free from flaws. Holes for pins shall be bored to the specified diameter and finished at right angles to the axis of the member. Pin holes shall be bored on completion of the assembly of built-up members. The size of the pin hole shall comply with Clause 17.10.4.

17.25.3.6 Curved members In order to meet a wide variety of manufacturing needs, cold forming/bending should be used rather than heat forming unless Approved. When heat forming cannot be avoided, heating should be as rapid as possible, particularly at temperatures of 240 °C and above. Maximum heat exposure time at temperature shall be as per CSA W59.2. A detailed procedure for the heat-forming/bending operation shall be submitted for review. The procedure shall describe the (a) type of heating to be employed; (b) the extent of the heating patterns; (c) the sequence of operations; and (d) the method of support of the member, including an assessment of any dead-load stresses present during the operation. Knowledge of the aluminum alloy being curved, including mechanical and other physical qualities, shall be necessary to prevent serious problems from occurring. Experience with aluminum forming and bending techniques shall be mandatory.

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Table 17.10 Recommended minimum bend radii for 90° cold bends of sheet and plate (See Clause 17.25.3.3.3.) Alloy

5052

5083

6061

Temper

Radii for various thicknesses expressed in terms of thickness, t 3.2 mm (1/8 in)

4.8 mm (3/16 in)

6.4 mm (1/4 in)

9.5 mm (3/8 in)

12.7 mm (1/2 in)

O

1/2t

1t

1t

1-1/2t

1-1/2t

H32

1-1/2t

1-1/2t

1-1/2t

1-1/2t

2t

H34

2t

2t

2-1/2t

2-1/2t

3t

H36

2-1/2t

3t

3-1/2t

4t

4-1/2t

H38

3t

4t

5t

5-1/2t

6-1/2t

O

1t

1t

1t

1-1/2t

1-1/2t

H321

1-1/2t

1-1/2t

1-1/2t

2t

2-1/2t

O

1t

1t

1t

1-1/2t

2t

T4

1-1/2t

2-1/2t

3t

3-1/2t

4t

T6, T651

2-1/2t

3t

3-1/2t

4-1/2t

5t

Notes: (1) The radii listed are the minimum recommended for bending sheets and plates without fracturing in a standard press brake with air bend dies. Other types of bending operations might require larger radii or permit smaller radii. The minimum permissible radii will also vary with the design and condition of the tooling. (2) Alclad sheet in the heat-treatable alloys can be bent over slightly smaller radii than the corresponding tempers of the bare alloy. (3) Heat-treatable alloys can be formed over appreciably smaller radii immediately after solution heat treatment. (4) The reference test method is ASTM E290.

17.25.3.7 Identification marking Each member shall carry an erection mark for identification. Paint or ink marks shall be used.

17.25.4 Welded construction 17.25.4.1 General All fusion welding procedures, including those related to quality of work, techniques, repairs, and qualifications, shall comply with CSA W59.2, except where modified by Clauses 17.25.4.2 to 17.25.4.6. All welding shall be with an inert-gas-shielded arc process, such as gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), or plasma arc welding process (PAW); or friction stir welding, in accordance with the requirements of AWS D17.3/D17.3M.

17.25.4.2 Primary tension and fracture-critical members Members and components of members designated primary-tension or fracture-critical shall comply with Clauses 17.20 and 17.21, in addition to CSA W59.2.

17.25.4.3 Stud welds Stud welds shall comply with CSA W59.2.

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17.25.4.4 Submissions Welding procedure specifications, data sheets, and repair procedures that have been accepted by the Canadian Welding Bureau shall be submitted to the Owner in compliance with the Plans.

17.25.4.5 Certification of fabrication companies Any company undertaking welded fabrication in accordance with this Section shall be certified to Division 1 or 2 of CSA W47.2.

17.25.4.6 Web to flange fillet welds Where practicable, web to flange fillet welds shall be made continuously by mechanized or automatic welding. Welds may be repaired using either a semi-automatic or manual process, but the repaired weld shall blend smoothly with the adjacent welds.

17.25.5 Bolted construction 17.25.5.1 Assembly When assembled, all joint surfaces, including those adjacent to bolt heads, nuts, and washers, shall be free from loose scale, burrs, dirt, and foreign material that would prevent the solid seating of the parts.

17.25.5.2 Installation of bolts Only pretensioned ASTM A325 bolts shall be used in slip-critical joints.

17.25.5.3 Turn-of-nut tightening After the holes in a joint are aligned, a sufficient number of bolts shall be placed and brought to a snugtight condition to ensure that the parts of the joint are brought into full contact with each other. Following the initial snugging operation, bolts shall be placed in any remaining open holes and brought to snug-tightness. Re-snugging can be necessary in large joints. Two washers are to be used, one under head face and one under nut face. When all bolts are snug-tight, each bolt in the joint shall be further tightened by the applicable amount of relative rotation specified in Table 17.11 with tightening progressing systematically from the most rigid part of the joint to its free edges. During this operation, there shall be no rotation of the part not turned by the wrench unless the bolt and nut are match-marked to enable the amount of relative rotation to be determined.

Table 17.11 Nut rotation from snug-tight condition* (See Clauses 17.25.5.3 and 17.25.5.4.) Disposition of outer faces of bolted parts Both faces normal to the bolt axis or one face normal to the axis and the other sloped 1:20 (bevelled washers not used)

Both faces sloped 1:20 from normal to the bolt axis (bevelled washers not used)

Bolt length†

Turn from snug

Up to and including four diameters

1/3

Over four diameters and not exceeding eight diameters or 200 mm

1/2

Exceeding eight diameters or 200 mm

2/3

All lengths

3/4

*Nut rotation is rotation relative to a bolt regardless of whether the nut or bolt is turned. The tolerance on rotation is 30° over. This Table applies to coarse-thread, heavy-hex structural bolts of all sizes and lengths used with heavy-hex semifinished nuts. †Bolt length is measured from the underside of the head to the extreme end point.

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17.25.5.4 Inspection An inspector shall determine whether the requirements of Clauses 17.4.4, 17.25.2.2, and 17.25.5.1 to 17.25.5.3 have been met. Installation of bolts shall be observed to ascertain that a proper tightening procedure is employed. The turned element of all bolts shall be visually examined for evidence that they have been tightened. When properly installed, the tip of the bolt shall be flush with or outside the face of the nut. Tensions in bolts installed by the turn-of-nut method exceeding those specified in Clause 17.25.5.3 shall not be cause for rejection. When there is disagreement concerning the results of an inspection of bolt tension, the following arbitration procedure shall be used, unless a different procedure has been specified: (a) The inspector shall use an inspection wrench that is a manual or power torque wrench capable of indicating a selected torque value. (b) Three bolts of the same grade and diameter as those under inspection and representative of the lengths and conditions of those in the bridge shall be placed individually in a calibration device capable of measuring bolt tension. There shall be washers under the bolt head and under the nut. (c) When the inspection wrench is a manual wrench, each bolt specified in Item (b) shall be tightened in the calibration device by any convenient means to an initial tension of approximately 15% of the required fastener tension, and then to the minimum tension specified for its size in Clause 17.25.5.3. Tightening beyond the initial condition shall not produce greater nut rotation beyond that permitted by Table 17.11. The inspection wrench shall then be applied to the tightened bolt and the average torque necessary to turn the nut or head 5° in the tightening direction shall be determined. The average torque measured in these tests of three bolts shall be taken as the job inspection torque to be used in the manner specified in Item (e). The job inspection torque shall be established at least once each working day. (d) When the inspection wrench is a power wrench, it shall first be applied to produce an initial tension of approximately 15% of the required fastener tension and then adjusted so that it will tighten each bolt specified in Item (b) to a tension of at least 5% but not more than 10% greater than the minimum bolt tension specified for its size in Clause 17.25.5.3. This setting of the wrench shall be taken as the job inspection torque to be used in the manner specified in Item (e). Tightening beyond the initial condition shall not produce greater nut rotation than that permitted by Table 17.11. The job inspection torque shall be established at least once each working day. (e) Bolts represented by the sample specified in Item (b) that have been tightened in the bridge shall be inspected by applying, in the tightening direction, the inspection wrench and its job inspection torque to 10% of the bolts (but not fewer than two bolts) selected at random in each connection. If no nut or bolt head is turned by this application of the job inspection torque, the connection shall be accepted as being properly tightened. If any nut or bolt head is turned by the application of the job inspection torque, this torque shall be applied to all of the bolts in the connection, and all of the bolts whose nut or head is turned by the job inspection torque shall be retightened and re-inspected. Alternatively, the fabricator or erector may retighten all of the bolts in the connection and then resubmit the connection for inspection.

17.25.5.5 Reuse of bolts For slip-resistant connections only, bolt assemblies not preloaded to the required preload may be reused. Touch-up of pretensioned bolts in a multi-bolt joint shall not constitute a reuse unless a bolt becomes substantially unloaded as other parts of the joint are bolted.

17.25.5.6 Shop trial assembly Girders and other main components shall be preassembled in the shop in order to prepare or verify the field-splices. Components shall be supported in a manner consistent with the finished geometry of the bridge, as specified on the Plans, with allowance for any camber required to offset the effects of dead load deflection. Holes in the webs and flanges of main components shall be reamed or drilled to final size while in assembly. The components shall be pinned and firmly drawn together by bolts before reaming or drilling.

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Drifting done during assembly shall be sufficient only to align the holes and not to distort the aluminum. If necessary, reaming shall be used to enlarge holes. When a number of sequential assemblies are necessary because of the length of the bridge, the second and subsequent assemblies shall include at least one section from the preceding assembly to provide continuity of alignment. Trial assemblies shall be required for field splices. Each assembly shall be checked for camber, alignment, accuracy of holes, and fit-up of welded joints and milled surfaces. Corrective work, if necessary, shall be carried out at no cost to the Owner.

17.25.5.7 Holes drilled using numerically controlled machines As an alternative to the trial assembly specified in Clause 17.25.5.6, when the bolt holes have been prepared by numerically controlled drilling or using a suitable template, the accuracy of the drilling may be demonstrated by a check assembly consisting of the first components of each type to be made. If the check assembly is satisfactory, further assemblies of like components shall not be required. If the check assembly is unsatisfactory for any reason, the work shall be redone or repaired in a manner acceptable to the Owner. Further check assemblies shall be required, as specified by the Owner, to demonstrate that the required accuracy of fit-up has been achieved.

17.25.5.8 Match-marking Connecting parts that are assembled in the shop for reaming or drilling holes shall be match-marked. A drawing shall be prepared to show how the marked pieces should be assembled in the field to replicate the shop assembly.

17.25.6 Tolerances 17.25.6.1 Structural members Fabrication tolerances shall be in accordance with CAN/CSA-S16, except that the tolerance on the end distance of bolt holes shall be – 0, +2 mm, and columns and beams shall not deviate from straight by more than 1/960 of the length between points of lateral support. There may be a variation of 1 mm from the detailed length in the length of members that have both ends finished for contact bearing. Other members without finished ends may have a variation from the detailed length of not more than 2 mm for members 10 m or less in length, and not more than 4 mm for members over 10 m in length.

17.25.6.2 Abutting joints When compression members are butted together to transmit loads in bearing, the contact faces shall be milled or saw-cut. The completed joint shall have at least 75% of the entire contact area in full bearing, defined as not more than 0.5 mm separation, and the separation of the remainder shall not exceed 1 mm. At joints where loads are not transferred in bearing, the nominal dimension of the gap between main members shall not exceed 10 mm.

17.25.6.3 Facing of bearing surfaces The surface finish of bearing surfaces that are in contact with each other shall meet the roughness requirements specified in CSA B95 and Table 17.12. Surfaces of flanges that are in contact with bearing sole plates shall be flat within 0.5 mm over an area equal to the projected area of the bearing stiffeners and web. Outside this area, there may be a 2 mm deviation from flat. The bearing surface shall be perpendicular to the web and bearing stiffeners.

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Table 17.12 Facing of bearing surfaces roughness requirements (See Clause 17.25.6.3.) Surface roughness Contact surfaces

Micro-inches

Microns

Plates in contact as part of bearing assemblies

1000

25

Milled ends of compression members

500

13

Milled or ground ends of stiffeners

500

13

Bridge rollers or rockers

250

6

Pins and pin holes

125

3

Sliding bearings

125

3

17.25.6.4 Bearing plates Bearing plates shall meet the following: (a) aluminum bearing plates 50 mm or less in thickness may be used without planing if a satisfactory contact bearing is obtained; (b) aluminum bearing plates more than 50 mm thick but not more than 100 mm thick may be straightened by pressing or by planing on all bearing surfaces to obtain a satisfactory contact bearing; and (c) aluminum bearing plates more than 100 mm thick shall be planed on all bearing surfaces.

17.25.6.5 Fabricated components The tolerances for welded components shall comply with CSA W59.2. Bearing stiffeners fitted to bear shall have a minimum bearing contact area of 75% and a maximum separation of 1 mm over the remaining area. Fitted intermediate stiffeners shall have a minimum bearing contact area of 25% and a maximum separation of 2 mm.

17.25.7 Quality control 17.25.7.1 Qualification of inspectors Welding inspectors shall be qualified to CSA W178.2.

17.25.7.2 Non-destructive testing of welds Non-destructive testing of welds shall be to AWS D1.2 and CSA W59.2, and shall at least include the following: (a) visual inspection of all welds: (b) radiographic or ultrasonic inspection of groove welds in flanges and webs of built-up girders, as follows: (i) flange splices in tension or stress reversal zones: 100%; (ii) flange splices in compression zones: 25%; and (iii) web splices: 100% for one-half of the depth from the tension flange and 25% for the remainder of the web; (c) liquid penetrant inspection of web-to-flange fillet welds, as follows: (i) submerged-arc welds: 25%; (ii) semi-automatic welds: 50%; and (iii) manual welds: 100%; and

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(d) liquid penetrant inspection of fillet welds, as follows, for connection plates and stiffeners to which cross-bracing or diaphragms are attached: (i) for one-half of the depth from the tension flange: 100%; and (ii) transverse welds on tension flanges: I00%. Radiographic and ultrasonic testing shall be performed before assembly of the flanges to the webs.

17.25.7.3 Acceptance standards for weld defects Welds shall meet the acceptance standards for cyclically loaded structures in accordance with AWS D1.2 with respect to defects.

17.25.7.4 Repair of welds Welds that do not meet the acceptance standards specified in Clause 17.25.7.3 shall be removed, rewelded, and re-tested in accordance with CSA W59.2. Repairs and non-destructive testing of fracture-critical and primary-tension members shall require special Approval.

17.25.7.5 Identification of structural aluminum In the fabricator’s plant, the alloy and specification of the aluminum used for main components shall be identified by use of suitable markings or recognized colour coding. Cut pieces that are identified by piece mark and contract number need not continue to carry specification identification markings when it has been established that such pieces conform to the required material specifications. Records shall be kept to identify the heat number of the material and the corresponding mill test report for each component of a fracture-critical or primary tension member.

17.25.8 Transportation and delivery Structural aluminum shall be loaded for shipping, transported, unloaded, and stored clear of the ground at its destination without being excessively stressed, deformed, or otherwise damaged. Plate girders shall be transported with their webs in the vertical plane.

17.25.9 Erection 17.25.9.1 Erection conditions Components shall be lifted and placed using appropriate lifting equipment, temporary bracing, guys, or stiffening devices so that they are not overloaded or unstable. Additional permanent material may be provided, if Approved, to ensure that the member capacities are not exceeded during erection.

17.25.9.2 Falsework All falsework, including necessary foundations, required for the safe construction of a bridge shall be designed, furnished, maintained, and removed by the contractor. The contractor shall not use any of the material intended for use in the finished bridge for temporary purposes during erection, unless such use is Approved.

17.25.9.3 Removal of temporary bracing or guys Temporary bracing or guys shall be removed when nolonger required for the stability of the bridge, unless otherwise Approved.

17.25.9.4 Maintaining alignment and camber The bridge shall be erected to the proper alignment on plan and in elevation, taking into account the specified dead load camber.

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17.25.9.5 Field assembly Parts shall be assembled following the piece marks shown on the erection drawings and match-marks. Main girder splices and field connections shall have half their holes filled with fitting-up bolts and driftpins (half bolts and half pins) before the installing and tightening of the balance of the connection bolts. The fitting-up bolts may be the same bolts used in the installation. The pins shall be 1 mm larger in diameter than the bolts. Excessive drifting that distorts the metal and enlarges the holes shall not be allowed, although there may be reaming up to 2 mm over the nominal hole diameter.

17.25.9.6 Cantilever erection When cantilever erection is used, splices that support the cantilevering member shall be fully bolted before the cantilever is further extended or loaded.

17.25.9.7 Repairs to erected material With the exception of splices of main material, the correction of minor misfits involving minor amounts of reaming, cutting, and shimming shall be permitted. The correction of other shop fabrication, or any deformation resulting from handling or transportation that prevents the proper assembly and fitting of the parts, shall require Approval.

17.25.9.8 Field welding Any company undertaking field welding in accordance with this Section shall be certified to CSA W47.2. Field welding shall only occur with Approval and with sufficient shelter provided in accordance with CSA W59.2.

17.25.9.9 Attachments Tack welds intended to be used for attachments or for any other purpose shall not be used unless they subsequently become a part of the welds shown on the Plans. Tack welds that are not part of the welds shown on the Plans shall not be used on any portion of the girders.

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