Research Prog Programme ramme
Engineering Design of railway structures to the structural Eurocodes Part 1
Copyright © RAIL SAFETY S AFETY AND STANDARDS STAND ARDS BOARD LTD. 2009 20 09 ALL RIGHTS RESERVE D This publication may be reproduced free of charge for research, private study or for internal circulation within an organisation. This is subject to it being reproduced and referenced accurately and not being used in a misleading context. The material must be acknowledged as the copyright of Rail Safety and Standards Board and the title of the publication specified accordingly. For any other use of the material please apply to RSSB's Head of Research and Development for permission. Any additional queries can be directed to
[email protected] [email protected].. This publication can be accessed via the RSSB website: www.rssb.co.uk www.rssb.co.uk..
Disclaimer This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Mott MacDonald being obtained. Mott MacDonald accepts no responsibility or liability for the consequence of this document being used for a purpose other than the purp oses for which it was commissioned. Any person using or relying on the document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Mott MacDonald for all loss or damage resulting therefrom. Mott MacDonald accepts no responsibility or liability liability for this document to any party other than the person by whom it was commissioned. To the extent that this report is based on information supplied by other parties, Mott MacDonald accepts no liability for any loss or damage suffered by the client, whether contractual or tortious, stemming from any conclusions based on data supplied by parties other than Mott MacDonald and used by Mott MacDonald in preparing this report.
Copyright © RAIL SAFETY S AFETY AND STANDARDS STAND ARDS BOARD LTD. 2009 20 09 ALL RIGHTS RESERVE D This publication may be reproduced free of charge for research, private study or for internal circulation within an organisation. This is subject to it being reproduced and referenced accurately and not being used in a misleading context. The material must be acknowledged as the copyright of Rail Safety and Standards Board and the title of the publication specified accordingly. For any other use of the material please apply to RSSB's Head of Research and Development for permission. Any additional queries can be directed to
[email protected] [email protected].. This publication can be accessed via the RSSB website: www.rssb.co.uk www.rssb.co.uk..
Disclaimer This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Mott MacDonald being obtained. Mott MacDonald accepts no responsibility or liability for the consequence of this document being used for a purpose other than the purp oses for which it was commissioned. Any person using or relying on the document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Mott MacDonald for all loss or damage resulting therefrom. Mott MacDonald accepts no responsibility or liability liability for this document to any party other than the person by whom it was commissioned. To the extent that this report is based on information supplied by other parties, Mott MacDonald accepts no liability for any loss or damage suffered by the client, whether contractual or tortious, stemming from any conclusions based on data supplied by parties other than Mott MacDonald and used by Mott MacDonald in preparing this report.
List of Contents
Page
Applicable British Standards, Eurocodes, National Annexes and Other Referenced Publications Glossary Summary
S-1
Chapters and Appendices 1
Recommended Values where National Choice is Allowed in BS EN 1990:2002.
24
2 Recommended Values where National Choice is Allowed in Eurocodes, other than BS EN 1990:2002 + A1:2005. 33 3
4
5
6
7
Part 1 - Enhancement of Previous Studies
42
3.1
42
Load Comparison Factor
Comparison of Design Load Effects
43
4.1
Partial and Combination Factors 4.1.1 Eurocodes 4.1.2 British Standards 4.1.3 Deck Types
43 43 44 45
4.2
Variation of Load Classification Factor, α.
46
4.3
Variation of Dynamic Load Factor, Ф.
50
Live Load Surcharge on Substructures
53
5.1
53
Differences in Applied Actions
Longitudinal Actions
55
6.1
Traction
55
6.2
Braking
58
Accidental Actions
61
7.1
Derailment Effects
61
7.2
Collision Effects
64
8
Vertical Deformation and Rotation
66
9
Wind Effects
69
9.1
Wind - Ultimate Limit State 9.1.1 Summary of ULS Wind Combination Results
72 73
9.2
Wind - Serviceability Limit State 9.2.1 Summary of SLS Wind Combination Results
74 75
1
9.3
10
11
Discussion 9.3.1 Wind Only 9.3.2 Wind (Leading) and Railway Traffic 9.3.3 Railway Traffic (Leading) and Wind
76 76 76 77
Temperature Effects
78
10.1
Ultimate Limit State Actions
78
10.2
Serviceability Limit State Actions
79
10.3
Global Temperature Effects
80
10.4
Discussion
81
10.5
Thermal Gradient Effects 82 10.5.1 Temperature Only 82 10.5.2 Temperature Coexistent with Railway Loading, Temperature Leading Action 82 10.5.3 Temperature Coexistent with Railway Loading, Railway Loading Leading Action 83 10.5.4 Conclusion 83
Groups of Loads
84
List of Figures Figure 1: ULS Moments in Very Light Bridge Main Girder for Variation of α (Alpha) Figure 2: ULS Moments in Medium Weight Bridge Main Girder for Variation of α (Alpha) Figure 3: ULS Moments in Very Heavy Heavy Bridge Main Girder for Variation of α (Alpha) Figure 4: ULS Shear in Very Light Bridge Main Girder for Variation of α (Alpha) Figure 5: ULS Shear in Medium Weight Bridge Main Girder for Variation of α (Alpha) Figure 6: ULS Shear in Very Heavy Bridge Main Girder for Variation of α (Alpha) Figure 7: ULS Shear in Medium Weight Bridge Main Girder for Variation of Φ Figure 8: ULS Shear in Very Heavy Bridge Main Girder for Variation of Φ Figure 9: Comparison between Characteristic (Nominal) Traction Forces Figure 10: Comparison between ULS Traction Forces Figure 11: Comparison between Characteristic (Nominal) Braking Forces Figure 12: Comparison between ULS Braking Forces Figure 13: Comparison between Characteristic (Nominal) & ULS Longitudinal Train Forces Figure 14: Design Moments due to Derailment Effects Figure 15: Design Shears due to Derailment Effects Figure 16: BS EN 1991-2 Table 6.11 Groups of Loads
47 47 48 49 49 50 52 52 57 57 59 60 60 62 63 84
List of Tables Table 1: Documents and Standards Referenced Throughout the Study Table 2: Recommended Values in BS EN 1991-1-1 Table 3: Recommended Values in BS EN 1991-2 Table 4: Alternative Values for Traction and Braking BS EN 1991-2 Table 5: Recommended Values in BS EN 1992-2 Table 6: Recommended Values in BS EN 1993-2 Table 7: Recommended Values in BS EN 1994-2 Table 8: Eurocode SLS Partial and Combination Factors used for Investigating α and Φ Table 9: Eurocode ULS Partial and Combination Factors used for Investigating α and Φ Table 10: Eurocode ACC Partial and Combination Factors used for Investigating α and Φ Table 11: British Standards SLS Partial and Combination Factors used for Investigating α and Φ
2
7 33 35 36 37 39 40 43 44 44 45
Table 12: British Standards ULS Partial and Combination Factors used for Investigating α and Φ Table 13: British Standards ACC Partial and Combination Factors used for Investigating α and Φ Table 14: Comparison of ULS Bending Moments where α = 1,10 Table 15: Range of Factor Φ Considered i n Study Table 16: British Standards Live Load Surcharge Values and Partial Factors Table 17: Eurocode Live Load Surcharge Values and Partial Factors Table 18: Comparison of the Live Load Surcharge Effects on Typical Retaining Structures Table 19: Comparison between Traction Forces Table 20: Comparison between Braking Forces Table 21: Derailment Loads Table 22: Eurocode Collision Loading (Class A Structures) Table 23: GC/RC5510 Collision Loading Table 24: Comparison of Design Criteria for a Typical Pier in the Hazard Zone Table 25: Comparison of Deflections for the Typical Decks Studied Table 26: Summary of Deck Type 5 (Pre-stressed Concrete Beams) Deflections Table 27: Eurocode ULS Partial and Combination Factors used for Wind Study Table 28: British Standards ULS Partial and Combination Factors used for Wind Study Table 29: Summary of ULS Wind Combination Results Table 30: Eurocodes SLS Partial and Combination Factors used for Wind Study Table 31: British Standards SLS Partial and Combination Factors used for Wind Study Table 32: Summary of SLS Wind Combination Results Table 33: Eurocode ULS Partial and Combination Factors used for Temperature Study Table 34: British Standards ULS Partial and Combination Factors used for Temperature Study Table 35: Eurocode SLS Partial and Combination Factors used for Temperature Study Table 36: British Standards SLS Partial and Combination Factors used for Temperature Study Table 37: Summary of Expansion and Contraction with T0 Specified (+/- 10°C) Table 38: Summary of Expansion and Contraction with T0, not applied
3
45 45 46 51 53 53 54 56 58 62 64 65 65 66 66 72 72 73 74 74 75 78 79 79 80 80 81
Applicable British Standards, Eurocodes, National Annexes and Other Referenced Publications Standard or Report Reference BS 5400-1:1998 Incorporating Amendment No. 1 BS 5400-2:2006
BS 5400-3:2000 Incorporating Corrigendum No. 1
BS 5400-4:1990
BS 5400-5:1979 Reprinted, incorporating Amendment No. 1
BS 5400-10:1980:1980 Incorporating Amendment No. I
BS 7608:1993 Incorporating Amendment No. 1 BS 8002:1994 GC/RT5110 GC/RT5112 GC/RC5510 NR/GN/CIV/025 BS EN 1990:2002 DRAFT National Annex to BS EN 1990:2002 BS EN 1991-1-1:2002
Title Steel, concrete and composite bridges — Part 1: General statement Steel, Concrete and Composite Bridge Part 2: Specification for Loads Steel, concrete and composite bridges – Part3: Code of practice for design of steel bridges Steel, concrete and composite bridges — Part 4: Code of practice for design of concrete bridges Steel, concrete and composite bridges — Part 5: Code of practice for design of composite bridges Steel, concrete and composite bridges Part 10: Code of practice for fatigue Code of practice for Fatigue design and assessment of steel structures Code of practice for earth retaining structures Design Requirements for Structures Loading Requirements for the Design of Bridges Recommendations for the Design of Bridges The Structural Assessment of Underbridges Eurocode — Basis of Structural Design UK National Annex to Eurocode – Basis of Structural Design Eurocode 1: Actions on Structures – Part 1-1: General Actions – Densities, Selfweight, Imposed Loads for Buildings
4
Date Published 12 March 2003
September 2006
May 2001
June 1990
May 1982
March 1999
April 1993
April 1994 August 2000 May 1997 August 2000 June 2006 April 2002 2006
April 2002
BS EN 1991-2:2003
BS EN 1991-1-3:2003
BS EN 1991-1-4:2005
DRAFT National Annex to BS EN 1991-1-4:2005 BS EN 1991-1-5:2003
National Annex to BS EN 19911-5:2003 BS EN 1991-1-7:2005
DRAFT National Annex to BS EN 1991-2:2003
National Annex to BS EN 19911-3:2003
DRAFT National Annex to BS EN 1991-1-4:2005
National Annex to BS EN 19911-5:2003
BS EN 1992-1-1:2004
National Annex to BS EN 19921-1:2004
BS EN 1992-2:2005
Eurocode 1: Actions on Structures – Part2: Traffic Loads on Bridges Eurocode 1 — Actions on structures — Part 1-3: General actions — Snow loads Eurocode 1: Actions on structures - Part 1-4: General actions - Wind actions UK National Annex to Eurocode 1 - Part 1-4: General actions - Wind actions Eurocode 1: Actions on structures — Part 1-5: General actions — Thermal actions UK National Annex to Eurocode 1 — Part 1-5: General actions — Thermal actions Eurocode 1: Actions on structures — Part 1-7: General actions — Accidental actions UK National Annex to Eurocode 1: Actions on Structures – Part2: Traffic Loads on Bridges UK National Annex to Eurocode 1: Actions on structures — Part 1-3: General actions — Snow loads UK National Annex to Eurocode 1: Actions on structures - Part 1-4: General actions - Wind actions UK National Annex to Eurocode 1: Actions on structures – Part 1-5: General actions – Thermal actions Eurocode 2: Design of Concrete Structures Part 1-1: General Rules and Rules for Buildings UK National Annex to Eurocode 2: Design of Concrete Structures Part 1-1: General Rules and Rules for Buildings Eurocode 2: Design of Concrete Structures Part 2: Concrete Bridges Design and Detailing Rules
5
September 2003
July 2003
April 2005
June 2005
March 2004
April 2007
September 2006
Draft, dated 07/08/03.
December 2005
June 2005
April 2007
December 2004
December 2005
December 2005
National Annex to BS EN 19922:2005
UK National Annex to Eurocode 2: Design of concrete structures. Concrete bridges Design and detailing rules BS EN 1993-1-1:2005 Eurocode 3: Design of Steel Structures - Part 1-1: General Rules and Rules for Buildings DRAFT National Annex to BS UK National Annex to EN 1993-1-1:2005 Eurocode 3: Design of Steel Structures Part 1-1: General Rules and Rules for Buildings BS EN 1993-1-5:2006 Eurocode 3: Design of Steel Structures - Part 1-5: Plated Structural Elements BS EN 1993-1-8:2005 Eurocode 3: Design of Steel Structures - Part 1-8: Design of Joints BS EN 1993-1-9:2005 Eurocode 3: Design of Steel Structures - Part 1-9: Fatigue DRAFT National Annex to BS UK National Annex to EN 1993-1-9:2005 Eurocode 3: Design of Steel Structures Part 1-9: Fatigue BS EN 1993-2:2006 Eurocode 3: Design of Steel Structures - Part 2: Steel Bridges DRAFT National Annex to BS UK National Annex to EN 1993-2:2006 Eurocode 3: Design of Steel Structures Part 2: Steel Bridges BS EN 1994-1-1:2004 Eurocode 4: Design of composite steel and concrete structures — Part 1-1: General rules and rules for buildings BS EN 1994-2:2005 Eurocode 4 — Design of composite steel and concrete structures — Part 2: General rules and rules for bridges National Annex to BS EN 1994- UK National Annex to 2:2005 Eurocode 4: Design of composite steel and concrete structures – Part 2: General Rules and rules for bridges BS EN 1997-1:2004 Eurocode 7: Geotechnical Design Part 1: General Rules BS EN 1997-2:2007 Eurocode 7: Geotechnical Design Part 2: Ground Investigation and Testing ISBN No. 978-0-7277-3160-9 Designer‘s Guide to BS 1993-2 – C.R. Hendy and C.J.Murphy, Series Editor Haig Gulvanessian
6
December 2007
May 2005
Undated Draft.
October 2006
May 2005
May 2005 July 2007
October 2006
May 2007
February 2005
December 2005
December 2007
December 2004 April 2007
First Published 2007
ISBN No. 978-0-7277-3159-3
NETWORK RAIL REPORT
T696 RSSB REPORT 13410/R01 Rev B ERRI D216/RP1 96/48/EC
Designer‘s Guide to BS 1992-2 Eurocode 2: Design of Concrete Structures Part 2; Concrete Bridges – C.R. Hendy and D.A. Smith, Series Editor Haig Gulvanessian Appraisal of Eurocode for Railway Loading (by Scott Wilson for Network Rail) Appraisal of Eurocodes for Railway Loading EN 1992 Design Criteria for railway (by Gifford for RSSB) ERRI Fatigue of Railway Bridges, State of the Art Report Council Directive 96/48/EC on the interoperability of the trans European high-speed rail system
First Published 2007
July 2003
January 2008 May 2007 September 1999 July 1996
(referenced throughout this document as the High Speed TSI)
2001/16/EC
st
UIC776-3 1 Edition th UIC776-1 5 Edition
Directive 2001/16/EC of the European Parliament and of the Council on the interoperability on the conventional rail system (referenced throughout this document as the Conventional RailTSI) Deformation of Bridges Loads to be considered in railway bridge design
March 2001
January 1989 August 2006
Table 1: Documents and Standards Referenced Throughout the Study
7
Glossary Terms Term ACC British Standards
Document BS EN 1990:2002 Not Applicable
BS EN EQU
Not Applicable Not Applicable BS EN 1990:2002
Item Accidental design situation The current British Standards used in bridge design that include the BS5400 suite of standards and Network Rail and Railway Group Standards British Standard Euronorm (Eurocode) Limit state for loss of static equilibrium of the structure or any part of it considered as a rigid body, where: minor variations in the value or the spatial distribution of actions from a single source are significant, and the strengths of construction materials or ground are generally not governing.
FAT
BS EN 1990:2002
GEO
BS EN 1990:2002
Mott MacDonald NA Nom
Not Applicable Not Applicable Not Applicable
RSSB
Not Applicable
Seismic SLS STR
BS EN 1990:2002 Not Applicable BS EN 1990:2002
TSI
Not Applicable
UIC ULS
Not Applicable Not Applicable
8
Limit state for fatigue failure of the structure or structural members Limit state for the failure or excessive deformation of the ground where the strengths of soil or rock are significant in providing resistance. Mott MacDonald National Annex Nominal (equivalent to characteristic in BS ) Railway Safety and Standards Board Seismic design situation Serviceability Limit State Limit state for internal failure or excessive deformation of the structure or structural members, including footings, piles, basement walls etc, where the strength of construction materials of the structure governs. Technical Specification for Interoperability (mandatory) International Union of Railways Ultimate Limit State
Characters Character γfL γf3
Standard BS 5400-2:2006 BS 5400-3:2000 BS 5400-4:1990 BS 5400-5:1979
γm
BS 5400-3:2000 BS 5400-4:1990 BS 5400-5:1979
τl τy φ mfw
BS 5400-3:2000 BS 5400-3:2000 BS 5400-3:2000 BS 5400-3:2000
MR MULT
BS 5400-3:2000 BS 5400-3:2000
G
BS EN 1990:2002
P
BS EN 1990:2002
Q
BS EN 1990:2002 BS EN 1990:2002
α
BS EN 1991-2:2003
Φ
BS EN 1991-2:2003
Qvk
BS EN 1991-2:2003
qvk
BS EN 1991-2:2003
γM
BS EN 1992 (all) BS EN 1993 (all) BS EN 1994 (all)
Mcr d0 f ub f u e1
BS EN 1993-1-1:2005 BS EN 1993-1-8:2005 BS EN 1993-1-8:2005 BS EN 1993-1-8:2005 BS EN 1993-1-8:2005
9
Description Partial factor for a load A factor that takes account of inaccurate assessment of the effects of loading, unforeseen stress distribution in the structure, and variations in dimensional accuracy achieved in construction. Partial factor for a material property, also accounting for model uncertainties and dimensional variations Limiting shear strength of web Shear strength Aspect ratio of a web panel Factor used in determining limiting shear strength Limiting moment of resistance Moment of resistance if lateral torsional buckling is prevented Partial factor for permanent actions. Partial factor for Pre-stressing actions Partial factor for variable actions Partial factor for the combination of actions Load classification factor applied to characteristic loading for railway lines carrying rail traffic which is heavier or lighter than normal rail traffic. Dynamic factor which enhances the static load effects under Load Models 71, SW/0 & SW/2 Value of Vertical point loads in Load Models Value of Vertical uniformly distributed loads in Load Models Partial factor for a material property, also accounting for model uncertainties and dimensional variations Elastic Critical Moment. the hole diameter for a bolt ultimate tensile strength for bolt ultimate tensile strength the end distance from the centre of a fastener hole to the adjacent
p1
BS EN 1993-1-8:2005
η
BS EN 1994-1-1:2004
10
end of any part, measured in the direction of load transfer the spacing between centres of fasteners in a line in the direction of load transfer Degree of shear connection; coefficient
Executive Summary The commission to compare the design of railway structures in accordance with the Structural Eurocodes and the current British Standards was awarded by RSSB to Mott MacDonald in August 2007. This report summarises Mott MacDonald‘s findings and experiences in using the Eurocodes. Headline results are included in this summary section, along with outline details of the methodology used in achieving the objectives set out below. The main text of the report provides more details of the study and the principal outcomes. The appendices give a detailed breakdown of the work undertaken including graphs and a comprehensive results summary. Calculations supporting the results and conclusions reported were supplied to RSSB and may be available upon request. However, caution must be used as many of the standards and national annexes have been revised since the draft versions used in this study. Objectives The objectives of study T741, the design of railway structures to the Structural Eurocodes, are summarised below: Recommend values where national choice is permitted in BS EN 1990:2002. Confirm the appropriateness of the recommended values in the Eurocodes, other than BS EN 1990, where national choice is permitted. Complete and update earlier studies into the differences in actions (by other parties for Network Rail and RSSB). Compare the margin of capacity (utilisation) between the design of typical railway structural elements to current British Standards and the Eurocodes. Discuss significant differences between the current British Standards and the Eurocodes. Provide a commentary on the lessons learned from using the Eurocodes. Methodology In achieving the majority of the study‘s objectives, the detailed design of selected details for a number of typical railway bridges was undertaken. This enabled Mott MacDonald to determine a comparison between the margin of capacity (utilisation) for a variety of bridge components and to identify issues arising from design using the Eurocodes. The designs, to both the current British Standards and the Structural Eurocodes, were augmented by a series of stand alone studies that included: Investigating the sensitivity of varying the line classification factor, α, a factor for nonstandard railway loads.
Investigating the sensitivity of varying the dynamic factor, Φ, for railway loads in determining shear effects. Consideration of ‗Groups of Loads‘ Consideration of load effects not critical in designing the selected elements of the typical structures (for example wind and temperature). Investigating the differences in the approach to design for fatigue.
11
Design of Railway Structures to the Structural Eurocodes
Summary of Study The principal findings of the study are summarised in the table below. The results of design comparisons between the British Standards and the Eurocodes are described and discussed in more detail in the main text. The number of typical structures considered was limited to six superstructures and a generic substructure. Only the factors encountered during the design of the selected elements have been varied. Description of Investigation
Relevant Standards (refer to list of references for dates of publication)
Summary of Recommended Values, New Studies and Commentary
Recommending values where national choice is permitted in BS EN 1990:2002
BS EN 1990:2002 + A1:2005 (Annex A2)
The values in the draft National Annex are recommended with the following exceptions:
Draft National Annex to BS EN 1990:2002 + A1:2005 (Annex A2)
Table A2.4 (STR/GEO) (Set B) & (Set C), γ Q,Sup for wind. Draft National Annex value = 1,70. Recommended value = 1,50 to avoid over-design of wind-sensitive elements.
BS EN 1991-1-1:2002
The values in the National Annex are recommended with the following exception:
National Annex to BS EN 19911-1:2002
cl. 5.2.3 (1), the lower characteristic value of the density of ballast. National Annex 3 3 value = 17kN/m . Recommended value = 18kN/m for design of structural elements. Note that dynamic effects were not considered in this study and the recommended 3 value is generally taken as 17kN/m for dynamic analyses.
BS EN 1991-2:2003
The values in the draft National Annex are recommended.
Confirming the appropriateness of the recommended values in the Eurocodes other than BS EN 1990 where national choice is permitted.
Table A2.4 (STR/GEO) (Set B), γG,Sup for superimposed loads. Draft National Annex value = 1,20. Recommended value = 1,35 for ballast to ensure equivalent load effects as current British Standards.
Note only the factors c onsidered in the design of typical elements agreed with RSSB have been considered. Typical bridge designs
Draft National Annex BS EN 1991-2:2003 dated 07/08/2003
12
Design of Railway Structures to the Structural Eurocodes
Description of Investigation
Relevant Standards (refer to list of references for dates of publication)
Summary of Recommended Values, New Studies and Commentary
Typical bridge designs
BS EN 1992-2:2005
The values in the draft National Annex are recommended.
National Annex BS EN 19922:2005 dated 31/12/2007 Typical bridge designs
BS EN 1993-2:2006
The values in the draft National Annex are recommended.
Draft National Annex BS EN 1993-2:2006 dated 02/05/2007 Typical bridge designs
BS EN 1994-2:2005
The values in the Eurocode are recommended.
National Annex not available Investigating the sensitivity of varying the line classification factor, α
BS EN 1991-2:2003
Investigating the sensitivity of varying the dynamic factor, Φ
BS EN 1991-2:2003
Draft National Annex BS EN 1991-2:2003 dated 07/08/2003
Draft National Annex BS EN 1991-2:2003 dated 07/08/2003
The use of α = 1,1 will be mandatory for the design of new railway structures following the implementation of the Technical Specifications for Interoperability (Conventional Rail and High Speed Infrastructure TSI). ULS assessment is comparable with British Standards. SLS assessment will be more onerous but is unlikely to result in significant changes in section sizes, quantities of reinforcement or numbers of connectors. Uncertainty surrounding the validity of simple FAT assessment: BS EN 1991-2:2003 states simple FAT assessment not valid if α > 1,0 (see Error! Reference source not found. ). The use of Φ 3 for calculating shear effects due to transient load is recommended. The increased shear force due to the use of Φ 3 combined with α = 1,1 will lead to higher shear forces calculated in accordance with the Eurocodes compared with the current British Standards. The increase is unlikely to result in significant changes in section sizes or connection details.
13
Design of Railway Structures to the Structural Eurocodes
Description of Investigation
Relevant Standards (refer to list of references for dates of publication)
Summary of Recommended Values, New Studies and Commentary
Typical bridge designs
BS EN 1992-2:2005
The values in the draft National Annex are recommended.
National Annex BS EN 19922:2005 dated 31/12/2007 Typical bridge designs
BS EN 1993-2:2006
The values in the draft National Annex are recommended.
Draft National Annex BS EN 1993-2:2006 dated 02/05/2007 Typical bridge designs
BS EN 1994-2:2005
The values in the Eurocode are recommended.
National Annex not available Investigating the sensitivity of varying the line classification factor, α
BS EN 1991-2:2003
Investigating the sensitivity of varying the dynamic factor, Φ
BS EN 1991-2:2003
Draft National Annex BS EN 1991-2:2003 dated 07/08/2003
Draft National Annex BS EN 1991-2:2003 dated 07/08/2003
The use of α = 1,1 will be mandatory for the design of new railway structures following the implementation of the Technical Specifications for Interoperability (Conventional Rail and High Speed Infrastructure TSI). ULS assessment is comparable with British Standards. SLS assessment will be more onerous but is unlikely to result in significant changes in section sizes, quantities of reinforcement or numbers of connectors. Uncertainty surrounding the validity of simple FAT assessment: BS EN 1991-2:2003 states simple FAT assessment not valid if α > 1,0 (see Error! Reference source not found. ). The use of Φ 3 for calculating shear effects due to transient load is recommended. The increased shear force due to the use of Φ 3 combined with α = 1,1 will lead to higher shear forces calculated in accordance with the Eurocodes compared with the current British Standards. The increase is unlikely to result in significant changes in section sizes or connection details.
13
Design of Railway Structures to the Structural Eurocodes
Description of Investigation
Relevant Standards (refer to list of references for dates of publication)
Summary of Recommended Values, New Studies and Commentary
Braking
BS EN 1991-2:2003
The values in the current British Standard are recommended in the National Annex. The characteristic braking forces in the BS are greater than the Eurocode values. A maximum braking force of 6000kN is specified in the Eurocode. No such cut off exists in the current British Standards. At ULS the differences are less and for loaded lengths above 305m the Eurocode values are greater, until the maximum value is achieved. Design to the current Eurocode values for loaded lengths
