106505629-PIP-STE05121-Anchor-Bolt-Design-Guide.pdf

Job Number

parsons ENERGY & CHEMICALS Group

DESIGN GUIDE Project, Client, Location

Design Guide Number

Rev

Date

ECS-DGS-007 (PIP STE05121)

0

2/6/03

Sheet of

1

1

Design Guide Title

ANCHOR BOLT DESIGN GUIDE

COMPANY STANDARD

In-House Review

Client Approval

Design

Entire Design Guide Attached

Fabrication

Construction

_____________________

Revised Sheets Only Attached

Approvals Rev

Date

By

0

2/6/03

DB

Ck

Section

DB

Project Engineer

Remarks

Client

Initial Issue

This sheet is a record of each issue or revision to the subject specification. Each time this specification document is changed, only the new or revised sheets must be issued. The exact sheets changed and the nature of the change should be noted in the Remarks column; however, these remarks are not a part of the specification. The revised sheets shall become part of the original specification and shall be complied with in their entirety.

EGE-FRM-008 (2/06/03)

January 2003

Process Industry Practices Structural

PIP STE05121 Anchor Bolt Design Guide

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES In an effort to minimize the cost of process industry facilities, this Practice has been prepared from the technical requirements in the existing standards of major industrial users, contractors, or standards organizations. By harmonizing these technical requirements into a single set of Practices, administrative, application, and engineering costs to both the purchaser and the manufacturer should be reduced. While this Practice is expected to incorporate the majority of requirements of most users, individual applications may involve requirements that will be appended to and take precedence over this Practice. Determinations concerning fitness for purpose and particular matters or application of the Practice to particular project or engineering situations should not be made solely on information contained in these materials. The use of trade names from time to time should not be viewed as an expression of preference but rather recognized as normal usage in the trade. Other brands having the same specifications are equally correct and may be substituted for those named. All Practices or guidelines are intended to be consistent with applicable laws and regulations including OSHA requirements. To the extent these Practices or guidelines should conflict with OSHA or other applicable laws or regulations, such laws or regulations must be followed. Consult an appropriate professional before applying or acting on any material contained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Team and will be reviewed every 5 years. This Practice will be revised, reaffirmed, or withdrawn. Information on whether this Practice has been revised may be found at www.pip.org.

© Process Industry Practices (PIP), Construction Industry Institute, The University of Texas at Austin, 3925 West Braker Lane (R4500), Austin, Texas 78759. PIP member companies and subscribers may copy this Practice for their internal use. Changes, overlays, addenda, or modifications of any kind are not permitted within any PIP Practice without the express written authorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.

Not printed with State funds

January 2003

Process Industry Practices Structural

PIP STE05121 Anchor Bolt Design Guide Table of Contents 1. Introduction .................................. 3 1.1 1.2 1.3 1.4

Purpose ............................................. 3 Scope................................................. 3 Use of “Shall” and “Should” ............... 3 Dimensions ........................................ 3

2. References ................................... 3 2.1 2.2 2.3 2.4

Process Industry Practices ................ 3 Industry Codes and Standards .......... 3 Government Regulations ................... 4 Other References .............................. 5

5.5 Shear Strength of Anchors in a Circular Pattern................................ 11 5.6 Minimum Dimensions ...................... 11

6. Ductile Design .......................... 13 6.1 Ductile Design Philosophy ............... 13 6.2 Critical Areas Requiring Ductile Design.............................................. 13 6.3 Requirements for Ductile Design..... 13 6.4 Means to Achieve Ductile Design .... 14

7. Reinforcing Design .................. 15 3. Notation ....................................... 5 4. Materials...................................... 7 4.1 4.2 4.3 4.4

Anchors.............................................. 7 Sleeves .............................................. 8 Washers ............................................ 8 Corrosion ........................................... 9

5. Strength Design........................ 10 5.1 5.2 5.3 5.4

Loading ............................................ 10 Anchor Bolt Design Spreadsheet..... 10 Anchor Design Considerations ........ 10 Shear Strength of Anchors in a Rectangular Pattern......................... 11

Process Industry Practices

7.1 General ............................................ 15 7.2 Failure Surface ................................ 15 7.3 Reinforcing Design to Transfer Tensile Forces ................................. 16 7.4 Reinforcing to Transfer Shear Forces ................................... 17

8. Frictional Resistance ............... 17 8.1 General ............................................ 17 8.2 Calculating Resisting Friction Force................................... 18

9. Shear Lug Design..................... 18 9.1 Calculating Shear Load Applied to Shear Lug ........................................ 19 9.2 Design Procedure for Shear Lug Plate ............................... 19

Page 1 of 25

PIP STE05121 Anchor Bolt Design Guide

9.3 Design Procedure for Shear Lug Pipe Section....................19

10. Pretensioning............................20 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9

Advantages ......................................21 Disadvantages..................................21 When to Apply Pretensioning ...........21 Concrete Failure...............................21 Stretching Length .............................22 Pretensioning Methods.....................22 Relaxation ........................................23 Tightening Sequence .......................23 Recommended Tightening if Anchor Pretensioning Is Not Required .........23

January 2003

Examples 1. 2.

3. 4.

Column Plate Connection Using Anchor Bolt Design Spreadsheet . A-19 Column Plate Connection – Supplementary Tensile Reinforcing ................................... A-24 Shear Lug Plate Section Design .. A-25 Shear Lug Pipe Section Design ... A-27

Figures, Tables, and Examples.....25 Tables 1. 2. 3. 4.

Minimum Anchor Dimensions ........ A-1 Reinforcement Tensile Capacity and Development Length .............. A-2 Hairpin Reinforcement Design and Details ............................................ A-3 Pretension Load and Torque Recommendations ......................... A-4

Figures A. Anchor Details ................................ A-5 B-1. Concrete Breakout Strength of Anchors in Shear – Octagon “Weak” Anchors............... A-6 B-2. Concrete Breakout Strength of Anchors in Shear – Octagon “Strong” Anchors ............. A-7 C-1. Tensile Reinforcement – Vertical Dowels............................... A-8 C-2 Tensile Reinforcement – Vertical Hairpin ............................... A-9 D-1. Shear Reinforcement – Horizontal Hairpin......................... A-10 D-2. Shear Reinforcement – Closed Ties .................................. A-11 D-3. Shear Reinforcement – Anchored Reinforcement ............. A-12 D-4. Shear Reinforcement – Shear Angles................................ A-13 D-5. Shear Reinforcement – Strut-and-Tie Model...................... A-14 E. Minimum Lateral Reinforcement – Pedestal ....................................... A-15 F. Coefficients of Friction.................. A-16 G. Pretensioned Anchors for Turbines and Reciprocating Compressors.. A-17 H. Anchor-Tightening Sequence....... A-18

Page 2 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

1.

Introduction 1.1

Purpose This Practice provides the engineer and designer with guidelines for anchor design for use by the process industry companies and engineering/construction firms.

1.2

Scope This design guide defines the minimum requirements for the design of anchors in process industry facilities at onshore U.S. sites. Included are material selection, strength design, ductile design, reinforcing, shear lugs, and pretensioning.

1.3

Use of “Shall” and “Should” Throughout this Practice the word “shall” is used if the item is required by code, and the word “should” is used if the item is simply recommended or its use is a good practice.

1.4

Dimensions At the time of issue of this Practice, a metric version of the basic reference for Anchor Bolt Design, ACI 318, had not been developed; therefore this Practice was developed in English units only.

2.

References When adopted in this Practice, the latest edition of the following applicable codes, standards, specifications, and references in effect on the date of contract award shall be used, except as otherwise specified. Short titles will be used herein when appropriate. 2.1

Process Industry Practices (PIP) – PIP REIE686 – Recommended Practices for Machinery Installation and Installation Design

2.2

Industry Codes and Standards • American Concrete Institute (ACI) – ACI 318-02 - Building Code Requirements for Reinforced Concrete and Commentary – ACI 349-01 - Code Requirements for Nuclear Safety Related Concrete Structures, Appendix B – ACI 355.1R-91 - State-of-the-Art Report on Anchorage to Concrete • American Institute of Steel Construction (AISC) – AISC Manual of Steel Construction - Allowable Stress Design - Ninth Edition [Short title used herein is AISC ASD Manual.]

Process Industry Practices

Page 3 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

– AISC Manual of Steel Construction - Load and Resistance Factor Design (LRFD) - Third Edition [Short title used herein is AISC LRFD Manual.] – AISC Steel Design Guide Series 1- Column Base Plates, Some Practical Aspects of Column Base Selection, David T. Ricker • American Society for Testing and Materials (ASTM) – ASTM A36 - Specification for Carbon Structural Steel – ASTM A53 - Specification for Pipe, Steel, Black and Hot-Dipped, ZincCoated, Welded, and Seamless – ASTM A193 - Specification for Alloy-Steel and Stainless Steel Bolting Materials for High-Temperature Service – ASTM A307 - Specification for Carbon Steel Bolts and Studs, 60,000 psi Tensile Strength – ASTM A354 - Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners – ASTM A449 - Specification for Quenched and Tempered Steel Bolts and Studs – ASTM A563 - Specification for Carbon Steel and Alloyed Steel Nuts – ASTM F436 - Specification for Hardened Steel Washers – ASTM F1554 - Specification for Anchor Bolts, Steel, 36, 55, and 105 Ksi Yield Strength • American Society of Civil Engineers (ASCE) – Design of Anchor Bolts for Petrochemical Facilities, Task Committee on Anchor Bolt Design, 1997 [Short title used herein is ASCE Anchor Bolt Report.] – ASCE 7-2002 - Minimum Design Loads for Buildings and Other Structures • American Welding Society – AWS D1.1 - Structural Welding Code - Steel • International Code Council (ICC) – International Building Code (IBC) 2.3

Government Regulations Federal Standards and Instructions of the Occupational Safety and Health Administration (OSHA), including any additional requirements by state or local agencies that have jurisdiction in the state where the project is to be constructed, shall apply. • U.S. Department of Labor, Occupational Safety and Health Administration (OSHA) – OSHA 29 CFR 1910 - Industrial Safety and Regulatory Compliance

Page 4 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

2.4

Other References – Blodgett, Omar W., Design of Welded Structures, The James F. Lincoln Arc Welding Foundation, 1966

3.

Notation Note:

Force and stress units shown herein under “Notation” are lb and psi respectively. At times, it is more convenient to show these units in the text, tables, and examples as kips and ksi, respectively. Where this is done, the units will always be shown.

AN

= Projected concrete failure area of an anchor or group of anchors, for calculation of strength in tension, inches2

Ase

= Effective cross-sectional area of anchor, inches2

Ar

= Reinforcing bar area, inches2

Arb

= Required total area of reinforcing bars, inches2

Areq = Required bearing area of shear lug, inches2 AV

= Projected concrete failure area of an anchor or group of anchors, for calculation of strength in shear, inches2

AVo = Projected concrete failure area of one anchor, for calculation of strength in shear, when not limited by corner influences, spacing, or member thickness, inches2 AC

= Anchor circle diameter (Figures B-1 and B-2), inches2

C

= Clear distance from top of reinforcing bar to finished surface (concrete cover), inches

c

= Distance from the center of the anchor shaft to the edge of the concrete (Figure A), inches

c1

= Distance from the center of anchor shaft to the edge of the concrete in one direction, inches. Where shear force is applied to the anchor, c1 is in the direction of the shear force.

c2

= Distance from the center of an anchor shaft to the edge of the concrete in the direction orthogonal to c1, inches

D

= Octagonal pedestal “diameter” (flat to flat), inches

D

= Outside diameter of shear lug pipe section, inches

do

= Anchor diameter, inches

db

= Diameter of reinforcing bar, inches

ds

= Anchor sleeve diameter, inches

f′′c

= Compressive strength of concrete (shall not be taken as greater than 10,000 psi), psi

fut

= Anchor material minimum specified tensile strength, psi

Process Industry Practices

Page 5 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

Fy

= Anchor or shear lug material yield strength, psi

fy

= Reinforcing material yield strength, psi

G

= Grout thickness, inches

H

= Height of shear lug plate or pipe, in.

ha

= Overall length of anchor under the head or above the base nut (Figure A), inches

he’

= Length of anchor below the sleeve (Figure A), inches

hef

= Effective anchor embedment depth (Figure A), inches

hs

= Length of anchor sleeve (Figure A), inches

L

= Length of shear lug plate or pipe, inches

la, lb = Portions of standard hook development length (Table 3), inches ld

= Development length of reinforcing bar, inches

ldh

= Actual development length of standard hook in tension, inches

lhb

= Basic development length of standard hook in tension, inches

Mu

= Ultimate moment on shear lug plate or pipe, k-inches or k-inches/inches

Mn

= Nominal flexural strength of shear lug pipe, k-inches

n

= Number of anchors

Ncb

= Nominal concrete breakout strength in tension of a single anchor, lb

Ncbg = Nominal concrete breakout strength in tension of a group of anchors, lb Npn

= Nominal pullout strength in tension of a single anchor, lb

Ns

= Nominal strength of a single anchor in tension as governed by the steel strength, lb

Nsb

= Side-face blowout strength of a single anchor, lb

Nsbg = Side-face blowout strength of a group of anchors, lb P

= Normal compression force beneficial to resisting friction force, lb

P

= Anchor projection from top of concrete (Figure A), in.

P1

= Anchor projection below bottom nut for Type 2 anchors (Figure A), inches

s

= Anchor spacing, center to center, inches

S

= Section modulus of shear lug pipe, inches

t

= Thickness of the shear lug plate or pipe wall, inches

T

= Tensile rebar capacity, lb

Vapp = Applied shear load on shear lug, kip Vcb

Page 6 of 25

= Nominal concrete breakout strength in shear of a single anchor or shear lug, lb

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

Vcbg = Nominal concrete breakout strength in shear of a group of anchors, lb

4.

Vcp

= Nominal concrete pryout strength, lb

Vf

= Resisting friction force at base plate, lb

Vn

= Nominal shear strength, lb

Vs

= Nominal strength in shear of a single anchor as governed by the steel strength, lb

Vu

= Factored shear load, lb

W

= Width of shear lug plate perpendicular to shear force, inches

Wh

= Width of anchor head or nut, inches

X

= Clear distance between anchor nut and reinforcing bar, inches

φ

= Concrete strength reduction factor (This value varies; refer to text for value.)

φb

= Steel resistance factor for flexure

φv

= Steel resistance factor for shear

ψ7

= Modification factor, for strength in shear, to account for cracking, as defined in ACI 318-02, paragraph D.6.2.7

µ

= Coefficient of friction

Materials 4.1

Anchors Refer to the ASCE Anchor Bolt Report, chapter 2, for a description of and specifications for common materials for anchors. Unless a special corrosive environment exists, the following should be specified: a. For low- to moderate-strength requirements: ASTM A307 headed bolts, ASTM A36 rods, or ASTM F1554 grade 36 rods b. For higher strength requirements: ASTM A193 grade B7, ASTM F1554 grade 55 or grade 105, or ASTM A354 grade BC or grade BD The following table provides properties for the recommended anchor materials. Suitable nuts by grade may be obtained from ASTM A563. If ASTM F1554 grade 55 rods are specified, add the weldability supplement.

Process Industry Practices

Page 7 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

Properties for Recommended Anchor Materials Anchor Material Type A307 A36 or F1554 grade 36 F1554 grade 55 F1554 grade 105 A193 grade B7 do ≤ 2.5" Based on bolt 2.5" < do diameter (db) ≤ 4" (used for high4" < do temperature ≤ 7" service) A354 grade BC A354 grade BD A449 Based on bolt diameter (db)

4.2

1/4" < do ≤ 1" 1" < do ≤ 1.5" 1.5" < do ≤ 3"

Fy ksi Not clearly defined 36 55 105 105

fut ksi 60

Ductile? Yes

58 75 125 125

Yes Yes Yes Yes

95

115

Yes

75

100

Yes

109

125

Yes

130

150

Yes

92

120

Yes

81

105

Yes

58

90

Yes

Sleeves Anchors should be installed with sleeves when small movement of the bolt is desired after the bolt is set in concrete. The two most common examples follow: a. When precise alignment of anchors is required during installation of structural columns or equipment. In this situation, the sleeve should be filled with grout after installation is complete. b. When anchors will be pretensioned to maintain the bolt under continuous tensile stresses during load reversal. Pretensioning requires the bolt surface to be free; therefore, the top of these sleeves should be sealed or the sleeve should be filled with elastomeric material to prevent grout or water from filling the sleeve. Two types of sleeves are commonly used with anchors. A partial sleeve is primarily used for alignment requirements, whereas the full sleeve is used for alignment as well as for pretensioning. Sleeves do not affect the design of a headed anchor for tensile loading because the tension in the anchor is transferred to the concrete through the head, not the anchor–concrete bond. Sleeved anchors can resist shear forces only when the sleeve is filled with grout. Refer to PIP REIE686 for use of sleeves with anchor bolts in machinery foundations. For concrete cover requirements, refer to section 5.6.4 of this Practice.

4.3

Washers Washers are required for all anchor bolts. If the anchors are to be pretensioned (refer to section 10), a hardened washer conforming to ASTM F436 is required.

Page 8 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

The following table shows the PIP-recommended base plate hole diameter. The hole in the washer should be equal to the bolt diameter plus 1/16 inch. Recommended Base Plate Hole and Washer Size Anchor Bolt Dia. (Inches)

PIP-Recommended Base Plate Hole Diameter*

Outside Washer Dia. (Inches)

1/2

13/16

1-5/8

5/8

15/16

1-3/4

3/4

1-1/16

1-7/8

7/8

1-3/16

2-1/4

1

1-1/2

2 5/8

1-1/4

1-3/4

2-7/8

1-1/2

2

3-1/8

1-3/4

2-1/4

3-3/4

2

3

4-1/2

2-1/4

3-1/4

4-3/4

2-1/2

3-1/2

5

2-3/4

3-3/4

5-1/4

4

5-1/2

-

3 1/2

* Base plate hole size recommendations are based on AISC ASD Manual, ninth edition. Hole size recommendations in the current AISC LRFD Manual, third edition, have been revised and are larger.

4.4

Corrosion Corrosion of an anchor can seriously affect the strength and design life of the anchor. When deciding which anchor material to use or what precaution to take against corrosion, consider the following: a. Is the anchor encased in concrete or exposed to the elements? b. What elements will the anchor contact? •

Chemical compounds

•

Saltwater

•

Ground water

•

Caustic gases

c. What limitations are present, affecting anchor size, length, and material, fabrication options, availability, and cost? Galvanizing is a common option for ASTM A307 bolts and for ASTM A36 and ASTM F1554 grade 36 threaded rods. Stainless steel anchors are a costly option but may be required in some environments. Painting or coating the anchor will protect the anchor, but more maintenance may be required.

Process Industry Practices

Page 9 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

To reduce the amount of contact with corrosive substances, pier design and anchor arrangement should consider water collection and anchor environment. If the engineer determines that prolonged contact with a corrosive substance is unavoidable, a metallurgist should be consulted to determine alternate anchor materials or protective options.

5.

Strength Design Strength design, which utilizes factored loads, shall be in accordance with Appendix D of ACI 318-02. In this Practice, strength design will apply to headed bolts and headed stud anchors, solidly cast in concrete. In accordance with ASCE 7-2002, section A.9.9.1.7, the exclusion for bolts more than 2 inches in diameter or embedded more than 25 inches (shown in ACI 318-02, D.2.2) may be ignored; however only equation D-7 (not equation D-8) shall be used for checking the breakout strength in cracked concrete. ACI 318-02, D.6.2.7, states that for anchors located in a region of a concrete member where analysis indicates no cracking at service loads, the modification factor, ψ7, shall be equal to 1.4. The tops of pedestals are normally outside cracked regions; therefore ψ7 should be 1.4 for most pedestals. For anchors at beams and slabs, follow the guidelines of ACI 318-02, section D.6.2.7. 5.1

Loading Anchors shall be designed for the factored load combinations in accordance with ACI 318-02, section 9.2 or Appendix C. Care shall be taken to assure that the proper strength reduction factor, φ, is used. That is, if the load combinations in section 9.2 are used, then use the φ’s from section 9.2; if the load combinations from Appendix C are used, then use the φ’s from Appendix C.

5.2

Anchor Bolt Design Spreadsheet (Available to PIP Members Only) The Anchor Bolt Design Spreadsheet has been developed utilizing Appendix D of ACI 318-02 and this Practice. (The spreadsheet, which is available to PIP Member Companies only, not to PIP Subscribers, can be accessed via http://www.pip.org/members/irc/ under “Tools.”) The spreadsheet gives shear and tensile capacities of an anchor or anchor group and the concrete around it. The spreadsheet also lets the user know whether or not the anchor configuration is ductile (refer to section 6, this Practice). The user needs to use the spreadsheet in combination with Appendix D of ACI 318-02 and this Practice. The spreadsheet merely saves the user time in laborious calculations but is no substitute for the engineer’s knowledge and expertise. See Appendix Example 1 (this Practice) for an illustration of the use of the Anchor Bolt Design Spreadsheet.

5.3

Anchor Design Considerations To accommodate reasonable misalignment in setting the anchor bolts, base plates are usually provided with oversized holes. If the factored shear loads

Page 10 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

exceed the values that can be resisted by friction between the base plate and the grout (see sections 8 and 9), a suitable means must be provided to transfer the shear from the base plate to the foundation. This can be accomplished by the following: a. Either shear lugs are used, or b. A mechanism to transfer load from the base plate to the bolt without slippage is incorporated (such as welding washers in place). If no tensile force is applied to the anchors, the anchors need not be designed for tension. Where the tensile force is adequately transferred to properly designed rebar, there is no requirement to check for concrete breakout strength of the anchor or anchors in tension (Ncb or Ncbg). Refer to section 7.3. 5.4

Shear Strength of Anchors in a Rectangular Pattern In accordance with ACI 318, the concrete design shear strength of a group of anchors in a rectangular pattern shall be taken as the greater of the following: a. The design strength of the row of anchors closest to the edge perpendicular to the direction of force on the anchors b. The design strength of the row of anchors furthest from the edge if the anchors are welded to the attachment so as to distribute the force to all anchors c. Although not specifically accepted in ACI 318, the design strength of the furthest row, if closed shear ties or other mechanisms transfer the load to the row of anchors furthest from the edge. Refer to Figure D-2.

5.5

Shear Strength of Anchors in a Circular Pattern Anchor bolts for tall, vertical vessels are frequently not required to resist shear. The shear is resisted by friction created by the large compressive forces attributable to overturning. However anchor bolts for shorter horizontal vessels may be required to resist shear. Following are two alternative methods for designing the anchors to resist shear:

5.6

5.5.1

The design shear strength of an anchor group in a circular pattern can be determined by multiplying the strength of the weakest anchor by the total number of anchors in the circle. Refer to Figure B-1.

5.5.2

Alternatively, where closed shear ties or other mechanisms transfer the load from the weak to the strong anchors, the design shear strength of an anchor group in a circular pattern can be determined by calculating the shear capacity of the strong anchors. Refer to Figure B-2.

Minimum Dimensions Minimum edge distance and anchor spacing shall be in accordance with ACI 318 and should be in accordance with ASCE recommendations. Minimum embedment should be in accordance with the recommendations of the ASCE Anchor Bolt Report. Refer to Table 1 and Figure A of this Practice. (If supplementary reinforcement is added to control splitting or the anchor size is

Process Industry Practices

Page 11 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

larger than required to resist the load, then ACI 318 allows the following edge distances and anchor spacing to be reduced. Refer to ACI 318-02, section D.8. 5.6.1

Edge Distance a. ACI 318 requires cast-in headed anchors that will be torqued to have minimum edge distances of 6do. Otherwise, the only requirement for edge distance is that at least the same cover be present as required for (1) reinforcement cover (normally 2 inches) and (2) to prevent side-face blowout or concrete shear failure. b. For constructability reasons, the ASCE Anchor Bolt Report recommends a minimum edge distance of 4do for ASTM A307 or ASTM A36 bolts or their equivalent and 6do for high-strength bolts. c. According to PIP REIE686, the recommended edge distance for anchor bolts in machinery foundations is 4do, 6 inches minimum.

5.6.2

Embedment Depth No minimum embedment depth is specified in ACI 318 as long as the effective embedment depth is enough to resist uplift forces. If ductility is required, greater embedment may be necessary. The ASCE Anchor Bolt Report recommends a minimum embedment depth of 12 diameters. hef = 12do

5.6.3

Spacing between Anchors ACI 318 requires the minimum spacing between anchors to be at least 4do for untorqued cast-in anchors and 6do for torqued anchors.

5.6.4

Modification for Sleeves Where anchor sleeves are used, the preceding minimum dimensions should be modified as follows: a. Edge distance should be increased by an amount equal to half the sleeve diameter minus half the anchor diameter, 0.5(ds – do). b. Embedment length for anchors equal to or greater than 1 inch should not be less than the larger of 12 anchor diameters (12do) or the sleeve length plus 6 anchor diameters (sleeve length + 6do). For anchors less than 1 inch in diameter, the embedment length should not be less than the sleeve length plus 6 inches. c. Spacing between anchors should be increased by an amount equal to the difference between the sleeve diameter and the anchor diameter: s ≥ 4do + (ds – do) for A307/A36 anchors or their equivalent.

5.6.5

Modification for Anchor Bottom Plate If a plate is used at the bottom of the anchor, similar to that shown in Figure G, the edge distance should be increased by half of the plate

Page 12 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

width or diameter minus 1/2 Wh, and the spacing should be increased by the plate width or diameter minus Wh. 5.6.6

Anchor Projection Anchor bolts should project a minimum of two threads above the fully engaged nut(s).

6.

Ductile Design 6.1

Ductile Design Philosophy A ductile anchorage design can be defined as one in which the yielding of the anchor (or the reinforcement or the attachment to which the anchor attaches) controls the failure of the anchorage system. This will result in large deflections, in redistribution of loads, and in absorption of energy before any sudden loss of capacity of the system resulting from a brittle failure of the concrete (ASCE Anchor Bolt Report). Anchors embedded in concrete and pulled to failure fail either by pullout of the concrete cone or by tensile failure of the anchor itself. The former is a brittle failure and the latter is a ductile failure. A brittle failure occurs suddenly and without warning, possibly causing catastrophic tragedies. In contrast, a ductile failure will cause the steel to yield, elongate gradually, and absorb a significant amount of energy, often preventing structures from collapsing. Consequently, when the design of a structure is based upon ductility or energy absorption, one of the following mechanisms for ductility shall be used. 6.1.1

Anchors shall be designed to be governed by tensile or shear strength of the steel, and the steel shall be a ductile material (refer to section 4.1, this Practice).

6.1.2

In lieu of the guideline in section 6.1.1, the attachment connected by the anchor to the structure shall be designed so that the attachment will undergo ductile yielding at a load level no greater than 75 percent of the minimum anchor design strength.

This ductile design philosophy is consistent with that of ACI 318. 6.2

Critical Areas Requiring Ductile Design Anchors designed to resist critical loads, where magnitudes cannot be precisely quantified (e.g., where design is based upon energy absorption), shall be designed using the requirements for ductile design. Examples are anchors in areas of intermediate or high seismicity and anchors used for blast load resistance.

6.3

Requirements for Ductile Design If the mechanism described in section 6.1.1 is used, the ductile design is achieved when the anchoring capacity of the concrete is greater than that of the anchor in tension, in shear, or in a combination of both. This is a strength requirement and is independent of the magnitudes of the applied loads. If it can

Process Industry Practices

Page 13 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

be shown that failure that is due to tensile loads will occur before failure that is due to shear loads, then the anchor need only be ductile for tensile loads. (The reverse would also be true but would not normally be applicable to design.) The first step is to select the anchor size considering only the steel failure modes, that is by using 0.75φ φNs and 0.75φ φVs. In addition, make sure that the steel chosen is ductile steel as listed in section 4.1. The engineer will need to do the following calculations manually, using Appendix D of ACI 318-02. Comment: For PIP Member Companies, the loads and size can then be entered into the Anchor Bolt Design Spreadsheet, described in section 5.2, to check the second and third steps (next two paragraphs). The second step is to ensure that the concrete pullout capacities (concrete breakout strength in tension, pullout strength of anchor in tension, and concrete side-face blowout strength) are greater than the tensile steel capacity of the anchor: φNcb or φNcbg > φNs, φNpn > φNs, and φNsb or φNsbg > φNs The third step is to ensure that the concrete shear capacities (concrete breakout strength in shear and concrete pryout strength in shear) are greater than the steel shear capacity of the anchor: φVcb or φVcbg > φVs and φVcp > φVs In lieu of the preceding requirements, the attachment to the structure that is connected by the anchor to the foundation may be designed so that the attachment will undergo ductile yielding at a load level no greater than 75 percent of the minimum anchor design strength. 6.4

Means to Achieve Ductile Design If conditions as specified in section 6.3 cannot be met, the concrete capacity can be increased to achieve a ductile design using the following: 6.4.1

Increased Concrete Tensile Capacity Concrete tensile capacity can be increased by the following: a. Increasing concrete strength b. Increasing embedment depth c. Increasing edge distance (for near edge cases) d. Increasing anchor spacing (for closely spaced anchor group) In situations for which space is limited, such as anchors embedded in pedestals, the preceding methods may not be practical. For these cases, reinforcing bars can be placed close to the anchor to transfer the load. Refer to section 7.3.

6.4.2

Increased Concrete Shear Capacity Concrete shear capacity can be increased by the following:

Page 14 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

a. Increasing concrete strength b. Increasing edge distance (for near edge cases) c. Increasing anchor spacing (for closely spaced anchor group) If the preceding methods are impractical because of space limitations, reinforcing hairpins looped around the anchors can be designed to carry the entire shear. If this method is used, do not consider any contribution from concrete shear strength. Refer to section 7.4. Another alternative is the use of a shear lug. Refer to section 9. If this alternative is chosen, either the following item a or item b must be adhered: a. The shear lug needs to be designed to undergo ductile yielding before failure of the concrete. b. The attachment that the shear lug connects to must undergo ductile yielding at a load level no greater that 75 percent of the minimum shear lug design strength.

7.

Reinforcing Design 7.1

General When anchor embedment or edge distances are not sufficient to prevent concrete failure that is due to factored loads, or for a “ductile type” connection, if φNcb or φNcbg < φ Ns or φVcb or φVcbg < φVs, then reinforcing steel may be used to prevent concrete failure. The reinforcing needed to develop the required anchor strength shall be designed in accordance with ACI 318 and the following.

7.2

Failure Surface Reinforcement shall be fully developed for the required load on both sides of the failure surfaces resulting from tensile or shear forces. Development lengths and reinforcement covers shall be in accordance with ACI 318. 7.2.1

The failure surface resulting from the applied tension load shall be one of the following: a. For a single bolt, the failure surface is that of a pyramid, with the depth equal to the embedded depth of the anchor (hef) and the base being a square with each side equal to three times the embedded depth (3hef). (Refer to Figure RD.5.2.1(a) of ACI 318-02.) b. For a group of bolts where the bolts are closer together than 3hef, the failure surface is that of a truncated pyramid. This pyramid is formed by a line radiating at a 1.5-to-1 slope from the bearing edge of the anchor group, edge of nuts, toward the surface from which the anchors protrude. (Refer to Figure RD.5.2.1(b) of ACI 318-02.)

Process Industry Practices

Page 15 of 25

PIP STE05121 Anchor Bolt Design Guide

7.2.2

7.3

January 2003

The failure surface resulting from the applied shear load is defined as a half pyramid radiating at a 1.5-to-1 slope in all directions, originating at the top of the concrete where the anchor protrudes and ending at the free surface in the direction of the shear. (Refer to Figure RD.6.2.1(a) of ACI 318-02.) For multiple anchors closer together than three times the edge distance, c1, the failure surface is from the outermost anchors. (Refer to Figure RD.6.2.1(b) of ACI 318-02.)

Reinforcing Design to Transfer Tensile Forces (Refer to Figures C-1 and C-2 and Tables 2 and 3.) 7.3.1

The required area of reinforcing bars, Arb, per anchor is as follows: Arb = (Ase * Fy)/fy Obtain hef, the embedment depth of the anchor as follows: (Refer to Figure C-1.) hef = ld + C + (X + db/2)/1.5 a. Calculate ld, the development length of the reinforcing bars resisting the load, using ACI 318. Note that the number of bars can be increased and the size of the reinforcing bars can be decreased to reduce the development length when required. b. Add C, the concrete cover over the top of reinforcing bars to the finished surface. c. Add X, the clear distance from the anchor nut to the reinforcing bars. d. Add db/2, half the diameter of the reinforcing bars. Note that the reinforcing bars were probably sized during pedestal design. If more reinforcement is required by the pedestal design than required by the anchor load transfer, the reinforcing bar development length may be reduced by multiplying by the ratio of the reinforcing bar area required to the reinforcing bar area provided: ld required = ld x [(Arb) required / (Arb) provided] This reduction is in accordance with ACI 318-02, section 12.2.5, and cannot be applied in areas of moderate or high seismic risk.

7.3.2

Direct tensile loads can be transferred effectively by the use of “hairpin” reinforcement or vertical dowels according to the following guidelines: a. “Hairpin” legs and vertical dowels shall be located within hef/3 from the edge of the anchor head. b. “Hairpin” legs and dowels shall extend a minimum of ld, beyond the potential failure plane, or additional rebar area shall be provided to reduce the required embedment length (see section 7.3.1).

Page 16 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

c. Where tension reinforcement is designed, it should be designed to carry the entire tension force, excluding any contribution from the concrete. d. For an example design calculation using hairpins, see Appendix Example 2 (this Practice). 7.4

Reinforcing to Transfer Shear Forces 7.4.1

Several shear reinforcement configurations or assemblies can be considered effective to prevent failure of the concrete. Depending on the particular situation, one of the following types of shear reinforcement can be used: a. “Hairpins” wrapped around the anchors (Figure D-1) b. “Closed ties” transferring load to the stronger anchors (Figure D-2) c. “Anchored” reinforcing intercepting the failure plane (Figure D-3) d. “Shear angles” welded to anchors (Figure D-4) e. “Strut-and-tie model” (Refer to Appendix A of ACI 318-02 and Figure D-5 of this Practice.)

8.

7.4.2

Shear reinforcing shall extend a minimum of ld, beyond the potential failure plane. Where excess rebar is provided, ld, may be reduced by the ratio of the reinforcing bar area required divided by the reinforcing bar area provided. See section 7.3.1.

7.4.3

Where shear reinforcing is designed, it should be designed to carry the entire shear load, excluding any contribution from the concrete.

7.4.4

For pedestals, a minimum of two No. 4 ties or three No. 3 ties is required within 5 inches of the top of each pedestal. Refer to Figure E. Use of three ties is recommended near the top of each pedestal if shear lugs are used or if the pedestals are located in areas of moderate or high seismic risk.

Frictional Resistance 8.1

General Where allowed by code, anchors need not be designed for shear if it can be shown that the factored shear loads are transmitted through friction developed between the bottom of the base plate and the top of the concrete foundation. If there is moment on a base plate, the moment may produce a downward load that will develop friction even when the column or vertical vessel is in uplift. This downward load can be considered in calculating frictional resistance. Care shall be taken to assure that the downward load that produces frictional resistance occurs simultaneously with the shear load. In resisting horizontal loads, the friction resistance attributable to downward force from overturning moment may be used.

Process Industry Practices

Page 17 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

The frictional resistance can also be used in combination with shear lugs to resist the factored shear load. The frictional resistance should not be used in combination with the shear resistance of anchors unless a mechanism exists to keep the base plate from slipping before the anchors can resist the load (such as welding the anchor nut to the base plate). Note:

8.2

Before planning to weld the anchor nut to the base plate, the engineer should consult a welding specialist to determine whether this is practical. Depending on the metallurgy of the nut, the welding may require a special welding procedure.

Calculating Resisting Friction Force The resisting friction force, Vf, may be computed as follows: Vf = µP P

= normal compression force

µ

= coefficient of friction

The materials used and the embedment depth of the base plate determine the value of the coefficient of friction. (Refer to Figure F for a pictorial representation.) a. µ = 0.90 for concrete placed against as-rolled steel with the contact plane a full plate thickness below the concrete surface. b. µ = 0.70 for concrete or grout placed against as-rolled steel with the contact plate coincidental with the concrete surface. c. µ = 0.55 for grouted conditions with the contact plane between grout and as-rolled steel above the concrete surface.

9.

Shear Lug Design Normally, friction and the shear capacity of the anchors used in a foundation adequately resist column base shear forces. In some cases, however, the engineer may find the shear force too great and may be required to transfer the excess shear force to the foundation by another means. If the total factored shear loads are transmitted through shear lugs or friction, the anchor bolts need not be designed for shear. A shear lug (a plate or pipe stub section, welded perpendicularly to the bottom of the base plate) allows for complete transfer of the force through the shear lug, thus taking the shear load off of the anchors. The bearing on the shear lug is applied only on the portion of the lug adjacent to the concrete. Therefore, the engineer should disregard the portion of the lug immersed in the top layer of grout and uniformly distribute the bearing load through the remaining height. The shear lug should be designed for the applied shear portion not resisted by friction between the base plate and concrete foundation. Grout must completely surround the lug plate or pipe section and must entirely fill the slot created in the concrete. When using a pipe section, a hole approximately 2 inches in diameter should be drilled through the

Page 18 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

base plate into the pipe section to allow grout placement and inspection to assure that grout is filling the entire pipe section. 9.1

Calculating Shear Load Applied to Shear Lug The applied shear load, Vapp, used to design the shear lug should be computed as follows: Vapp = Vu - Vf

9.2

Design Procedure for Shear Lug Plate Design of a shear lug plate follows (for an example calculation, see Appendix Example 3, this Practice): a. Calculate the required bearing area for the shear lug: Areq = Vapp / (0.85 * φ * f′′c)

φ = 0.65

b. Determine the shear lug dimensions, assuming that bearing occurs only on the portion of the lug below the grout level. Assume a value of W, the lug width, on the basis of the known base plate size to find H, the total height of the lug, including the grout thickness, G: H = (Areq /W) + G c. Calculate the factored cantilever end moment acting on a unit length of the shear lug: Mu = (Vapp/W) * (G + (H-G)/2) d. With the value for the moment, the lug thickness can be found. The shear lug should not be thicker than the base plate: t = [(4 * Mu)/(0.9*Fy)]0.5 e. Design weld between plate section and base plate. f.

Calculate the breakout strength of the shear lug in shear. The method shown as follows is from ACI 349-01, Appendix B, section B.11: φ*[f’c]0.5 Vcb = AV*4*φ where AV = the projected area of the failure half-truncated pyramid defined by projecting a 45-degree plane from the bearing edges of the shear lug to the free edge. The bearing area of the shear lug shall be excluded from the projected area. φ = concrete strength reduction factor = 0.85

9.3

Design Procedure for Shear Lug Pipe Section Design of a shear lug pipe section follows (for an example calculation, see Appendix Example 4, this Practice): a. Calculate the required bearing area for the shear lug:

Process Industry Practices

Page 19 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

Areq = Vapp /(0.85φ φf′′c)

φ = 0.60

b. Determine the shear lug dimensions, assuming that bearing occurs only on the portion of the lug below the grout level. Assume the D, diameter of the pipe section, based on the known base plate size to find H, the total height of the pipe, including the grout thickness, G: H = (Areq/D) + G c. Calculate the factored cantilever end moment acting on the shear lug pipe: M = Vapp * (G + (H-G)/2) d. Check the applied shear force and the bending moment for pipe section failure (AISC LRFD Manual, pages 6-113, 6-116). Shear check– φv Vn ≥ Vapp where φv = 0.9 and Vn = 0.6 Fy π(D2 – (D-2t)2)/4 Moment check– φb Mn ≥ Mu where φb = 0.9 and Mn = S * [{600/(D/t)} + Fy] e. Design weld between pipe stub section and base plate. f.

10.

Check the breakout shear as shown in section 9.2(f).

Pretensioning Pretensioning induces preset tensile stresses to anchor bolts before actual loads are applied. When properly performed, pretensioning can reduce deflection, avoid stress reversal, and minimize vibration amplitude of dynamic machinery. Pretensioning may be considered for the following: a.

Towers more than 150 feet tall

b.

Towers with height-to-width ratios of more than 10

c.

Dynamic machinery such as compressors (PIP REIE686)

However, pretensioning adds cost, and the stress level is difficult to maintain because of creep and relaxation of the bolt material. AISC does not recommend pretensioning anchors. The AISC LRFD Manual paragraph C-A3.4 states, “The designer should be aware that pretensioning anchor bolts is not recommended due to relaxation and stress corrosion after pretensioning.” AISC Steel Design Guide Series 1, anchor bolt section states, “Because of long-term relaxation of concrete, prestressing of anchor bolts is unreliable and hardly ever justified.” In practical applications, the engineer should decide whether to pretension the anchor bolt by considering the following advantages and disadvantages:

Page 20 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

10.1

Advantages The advantages of pretensioning are as follows: a. Can prevent stress reversals on anchors susceptible to fatigue weakening b. May increase dampening for pulsating or vibrating equipment c. Will decrease, to some extent, the drift for process towers under wind or seismic load d. Will increase the frictional shear resistance for process towers and other equipment

10.2

Disadvantages The disadvantages of pretensioning are as follows: a. Can be a costly process to install accurately b. No recognized code authority that gives guidance on the design and installation of pretensioned anchors. There is little research in this area. c. Questionable nature about the long-term load on the anchor from creep of concrete under the pretension load d. Possible stress corrosion of the anchors after pretensioning e. Typically, no bearing resistance to shear on the anchor. This is because during pretensioning, the sleeve around the anchor typically is not filled with grout. f.

Little assurance that the anchor is properly installed and pretensioned in the field

g. Possible direct damage from pretensioning. The pretensioning itself can damage the concrete if not properly designed or if the pretension load is not properly regulated. 10.3

When to Apply Pretensioning Pretensioning should be considered for vertical vessels that are more than 150 feet tall or for those with height-to-width ratios of more than 10 and if recommended by the equipment manufacturer; pretensioning is required if required for warrantee. When not otherwise specified, anchors for turbines and reciprocating compressors should be torqued to the values shown in Table 4.

10.4

Concrete Failure In certain situations, the use of high-strength anchors in concrete with high pretension forces may exceed the ultimate capacity of the concrete by prematurely breaking out the concrete in the typical failure pyramid. Whether this situation can occur depends on the depth of the anchor and on other factors, such as edge conditions and arrangement of the base plate. To ensure that premature concrete failure does not occur, pretensioned anchors shall be designed so that the breakout strength of the anchor in tension is greater than the maximum pretension force applied to the anchor. In the case of a stiff base plate

Process Industry Practices

Page 21 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

covering the concrete failure pyramid, the stresses induced by external uplift on the concrete are offset by the clamping force and the gravity loads. For this case, the breakout strength needs only to be designed for the amount that the external uplift exceeds the gravity plus pretensioning force loads. 10.5

Stretching Length Prestressing should be implemented only when the stretching (spring) length of the anchor extends down near the anchor head of the anchor. On a typical anchor embedment, where there is no provision for a stretching length, if a prestressing load is applied to the anchor, the anchor starts to shed its load to the concrete through its bond on the anchor. At that time, a high bond stress exists in the first few inches of embedment. This bond will relieve itself over time and thereby reduce the prestress load on the anchor. Therefore it is important to prevent bonding between the anchor and concrete for pretensioned anchors. Refer to Figure G for a suggested detail.

10.6

Pretensioning Methods Methods used to apply preload are as follows: 10.6.1 Hydraulic jacking: Hydraulic jacking is the most accurate method and is recommended if the pretension load is essential to the integrity of the design. The anchor design should accommodate any physical clearance and anchor projections required for the hydraulic equipment. 10.6.2 Torque wrench: Torque wrench pretensioning provides only a rough measure of actual pretension load but can be the method of choice if the amount of pretension load is not critical. Torque values are shown in Table 4. 10.6.3 Turn-of-nut: This method is the easiest to apply, but there are questions as to the accuracy of the pretension load. The pretension load from stretching the anchor can be closely determined, but accounting for the compression of the concrete between the base plate and the nut at the bottom of the anchor is difficult. Per the ASCE Anchor Bolt Report, the required amount of nut rotation from the “snug tight” condition to produce a desired tensile stress in the bolt (ft) can be determined using the following formula. Nut rotation in degrees = (360 l Ase ft Tlc) / (E Ad) where:

Page 22 of 25

l

=

bolt stretch length (the distance between the top and bottom nuts on the bolt)

Ase

=

tensile stress area of bolt

ft

=

desired tensile stress

Tlc

=

bolt threads per unit length

E

=

elastic modulus of bolt

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

Ad

=

nominal bolt area

If the bolt is to be retightened to compensate for any loss of pre-load, this method requires that nuts be loosened, brought to a “snug tight” condition, and then turned the number of degrees originally specified. 10.6.4 Load indicator washers: This method is good if the amount of pretension desired is as much as the required load in slip-critical structural steel connections. These loads are typically very high and not normally required for anchors. 10.7

Relaxation According to ACI 355.1 R, section 3.2.2, “If headed anchors are pretensioned, the initial force induced in the anchor is reduced with time due to creep of the highly stressed concrete under the anchor head. The final value of the tension force in the anchor depends primarily on the value of bearing stresses under the head, the concrete deformation, and the anchorage depth. In typical cases the value of that final force will approach 40 to 80 percent of the initial preload (40 percent for short anchors, 80 percent for long anchors).” Retensioning the anchors about 1 week after the initial tensioning can reduce the loss of preload. According to ACI 355.1R, the reduction of the initial preload can be reduced by about 30 percent by retensioning.

10.8

Tightening Sequence Pretensioned anchors should be tightened in two stages: a. First stage should apply 50 percent of the full pretension load to all anchors. b. Second stage should apply full pretension load to all anchors. Anchors should be tightened in a crisscross pattern. (Refer to Figure H.)

10.9

Recommended Tightening if Anchor Pretensioning Is Not Required Anchors should be brought to a snug, tight condition. This is defined as the tightness that exists after a few impacts from an impact wrench or the full effort of a man using a spud wrench. At this point all surfaces should be in full contact.

Process Industry Practices

Page 23 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

This page is intentionally blank.

Page 24 of 25

Process Industry Practices

PIP STE05121 Anchor Bolt Design Guide

January 2003

Appendix Figures, Tables, and Examples

Process Industry Practices

Page 25 of 25

PIP STE05121 Anchor Bolt Design Guide

January 2003

TABLE 1: Minimum Anchor Dimensions (Refer to Figure A.)

HEAVY HEX HEAD/ NUT

ANCH. TYPE 2

ASCE ANCHOR BOLT REPORT MINIMUM DIMENSIONS (Refer to Section 5.6)1 hef

P1

ANCHOR WIDTH DIA. Wh do

12do do + 1/2"

(in.) 1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-3/8 1-1/2 1-3/4 2 2-1/4 2-1/2 2-3/4 3

(in.) 1.00 1.25 1.44 1.69 1.88 2.06 2.31 2.50 2.75 3.19 3.63 4.06 4.50 4.94 5.31

(in.) 1.00 1.13 1.25 1.38 1.50 1.63 1.75 1.88 2.00 2.25 2.50 2.75 3.00 3.25 3.50

(in.) 6.0 7.5 9.0 10.5 12.0 13.5 15.0 16.5 18.0 21.0 24.0 27.0 30.0 33.0 36.0

2

EDGE DISTANCE c

HIGHA307/A36 STRENGTH F1554 OR Grade 36 TORQUED BOLTS 4do ≥ 4.5"

6do ≥ 4.5"

(in.) 4.5 4.5 4.5 4.5 4.5 4.5 5.0 5.5 6.0 7.0 8.0 9.0 10.0 11.0 12.0

(in.) 4.5 4.5 4.5 5.3 6.0 6.8 7.5 8.3 9.0 10.5 12.0 13.5 15.0 16.5 18.0

SLEEVES

SPACING

SHELL SIZE

he '

4do Diameter Height 6do ≥ 6" ds hs (in.) 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 7.0 8.0 9.0 10.0 11.0 12.0

(in.) 2 2 2 2 3 3 3 4 4 4 4 4 6 6 6

(in.) 5 7 7 7 10 10 10 15 15 15 18 18 24 24 24

(in.) 6 6 6 6 6 7 8 8 9 11 12 14 15 17 18

1

IF SLEEVES ARE USED, EMBEDMENT SHALL BE THE LARGER OF 12do or (hs + he') INCREASE EDGE DISTANCE BY 0.5(ds - do) INCREASE SPACING BY (ds - do)

2

FOR MACHINERY FOUNDATIONS PIP REIE686 REQUIRES A MINIMUM EDGE DISTANCE OF 6 INCHES.

Process Industry Practices

Page A-1

PIP STE05121 Anchor Bolt Design Guide

January 2003

TABLE 2: Reinforcement Tensile Capacity and Tensile Development Length Reinforcement Yield Strength, fy = 60 ksi Compressive Strength of Concrete, f'c = 3,000 psi Design Tensile Strength Reduction Factor, φ = 0.90 (ACI 318-02, Section 9.3) Reinforcement Location Factor, α = 1.3 (Top Reinforcement), 1.0 (Other Reinforcement) Coating Factor, β = 1.0 (Uncoated Reinforcement) Reinforcement Size Factor, γ = 0.8 (≤ #6 bar), 1.0 (> #6 bar) Lightweight Aggregate Concrete Factor, λ = 1.0 (Normal Weight Concrete) Transverse Reinforcement Index, Ktr = 0 (Design Simplification) ACI 318-02 , Section 12.2.3 - Tension Development Length: ld = db (3/40) [fy/(f'c)1/2] (αβγλ)/[(c + Ktr)/db]

(12-1)

[(c + Ktr)/db ≤ 2.5]

where c is the smaller of either the distance from the center of the bar to the nearest concrete surface or one-half the center-to-center spacing of the bars BAR SIZE

#3 #4 #5 #6 #7 #8 #9 #10 #11

BAR BAR AREA CAPACITY Ar

φ*Ar*(fy)

(sq. in.)

(Kips)

0.11 0.20 0.31 0.44 0.60 0.79 1.00 1.27 1.56

5.94 10.80 16.74 23.76 32.40 42.66 54.00 68.58 84.24

SPACING ≥ 3.0 in. REQUIRED COVER

SPACING ≥ 6.0 in.

c = 3.0 in.

TENSION DEVELOPMENT TENSION DEVELOPMENT REQUIRED LENGTH, ld LENGTH, ld COVER TOP OTHER TOP OTHER

(in.)

(in.)

(in.)

≥ 1:5/16 ≥ 1:1/4 ≥ 1:3/16 ≥ 1:1/8 ≥ 1:1/16 ≥1 ≥ 15/16 ≥ 7/8 ≥ 13/16

13 17 22 32 55 71 91 115 142

12 13 17 25 42 55 70 89 109

FACTORS FOR DIFFERENT VALUES OF f'c (Note: ld shall not be less than 12 inches.) DEVELOPMENT f'c LENGTH FACTOR 3,000 1.00 4,000 0.87 5,000 0.77 6,000 0.71

Process Industry Practices

c = 1.5 in.

(in.)

(in.)

≥ 2:13/16 13 ≥ 2:3/4 17 ≥ 2:11/16 22 ≥ 2:5/8 26 ≥ 2:9/16 38 ≥ 2:1/2 43 ≥ 2:7/16 48 ≥ 2:3/8 58 ≥ 2:5/16 71 SPACING ≥ 12.0 in. #3 #4 #5 #6 #7 #8 #9 #10 #11

≥ 5:13/16 ≥ 5:3/4 ≥ 5:11/16 ≥ 5:5/8 ≥ 5:9/16 ≥ 5:1/2 ≥ 5:7/16 ≥ 5:3/8 ≥ 5:5/16

13 17 22 26 38 43 48 55 61

(in.) 12 13 17 20 29 33 37 44 55 c = 6.0 in. 12 13 17 20 29 33 37 42 47

Page A-2

PIP STE05121 Anchor Bolt Design Guide

January 2003

TABLE 3: Hairpin Reinforcement Design and Details Reinforcement Yield Strength, fy = 60 ksi Compressive Strength of Concrete, f' c = 3,000 psi

la

lb

f*Ar*(fy) (kips) 5.94 10.80 16.74 23.76 32.40 42.66 54.00 68.58 84.24

0.7*ldh (in.) 6.0 7.7 9.6 11.5 13.4 15.3 17.3 19.5 21.6

(in.) 2.0 3.2 4.6 5.5 6.4 7.3 7.1 8.0 8.9

(in.) 4.0 4.5 5.0 6.0 7.0 8.0 10.2 11.4 12.7

ACI 12.5.1 & Fig. R12.5.1

OTHER BARS ld (a) (ACI INSIDE 12.2.3) HOOK (in.) 2.3 3.0 3.8 4.5 5.3 6.0 9.5 10.8 12.0 (a)

(in.) 12 13 17 25 42 55 70 89 109

TOP BARS ld (a) (ACI 12.2.3)

CAPACITY SEE NOTE (4)

(in.) 8.2 11.0 13.7 16.4 19.2 21.9 24.7 27.8 30.9

ldh

VERTICAL AND HORIZONTAL HAIRPINS

(ACI/ CRSI)

(0.02βλfy/(f'c)0.5)db (ACI 12.5.2 )

HAIRPIN AND HOOK DIMENSIONS

CAPACITY SEE NOTE (4)

#3 #4 #5 #6 #7 #8 #9 #10 #11

180 DEG HOOK DEVELOPMENT LENGTH ldh =

REINFORCING BAR CAPACITY

REINFORCEMENT BAR SIZE

Minimum Reinforcement Cover = 2.5 in. Minimum Reinforcing Spacing = 3.0 in. Coating Factor, β = 1.0 (Uncoated Reinforcement) Lightweight Aggregate Concrete Factor, λ = 1.0 (Normal Weight Concrete) Development Length Reduction Factor (ACI 318-02 , Paragraph 12.5.3a) = 0.70 Design Tensile Strength Reduction (ACI 318-02, Paragraph 9.3.2.1), φ = 0.90

(kips) 6.91 13.40 21.22 29.06 37.36 48.37 59.54 74.83 91.15

(in.) 13 17 22 32 55 71 91 115 142

(kips) 6.84 12.80 20.19 27.84 36.22 47.06 58.26 73.39 89.56

FACTORS FOR DIFFERENT VALUES OF f'c:

f'c

Development Length Factor (D)

3,000 4,000 5,000 6,000 lb remains the same. T (hairpin ) = T (hook) x (1+l a/ld) HAIRPIN CAPACITY:

1.00 0.87 0.77 0.71

ldh = ldh*(D) la = ldh-lb

(1) Standard 180 hook capacity = capacity of straight bar (2) Capacity of la portion of hook = bar capacity X (la/ld) [ld > la] (3) Capacity of lb portion of hook = bar capacity - capacity of la portion (4) Hairpin capacity = bar capacity X (1 + la/ld) where ld = bar development length [ld > la]

Process Industry Practices

Page A-3

PIP STE05121 Anchor Bolt Design Guide

January 2003

TABLE 4: Pretension Load and Torque Recommendations*

Nominal Bolt Diameter (inches) 1/2 5/8 3/4 7/8 1 1-1/8 1-1/4 1-1/2 1-3/4 2 2-1/4 2-1/2 2-3/4 3

Number of Threads (per inch) 13 11 10 9 8 8 8 8 8 8 8 8 8 8

Torque (foot-pounds) 30 60 100 160 245 355 500 800 1,500 2,200 3,180 4,400 5,920 7,720

Pretension Load (pounds) 3,780 6,060 9,060 12,570 16,530 21,840 27,870 42,150 59,400 79,560 102,690 128,760 157,770 189,720

Note 1: All torque values are based on anchor bolts with threads well lubricated with oil. Note 2: In all cases, the elongation of the bolt will indicate the load on the bolt. Note 3: Based upon 30-ksi internal bolt stress * From PIP REIE686, Recommended Practices for Machinery Installation and Installation Design, Appendix A.

Process Industry Practices

Page A-4

PIP STE05121 Anchor Design Guide

January 2003

C EDGE DIST.

ds

he'

do

TYPE 1 C EDGE DIST.

ds

P1

do

he'

hef

ha

hs

P

T.O. CONC.

PROJECTION

hef

ha

hs

T.O. CONC.

P PROJECTION

FIGURE A: Anchor Details

TACK WELD NUT

TYPE 2 NOTE: DISTANCE BETWEEN BOTTOM OF SLEEVE AND ANCHOR BEARING SURFACE, he' , SHALL NOT BE LESS THAN 6d o NOR 6-IN. REFER TO TABLE 1 FOR MINIMUM DIMENSIONS

Process Industry Practices

Page A-5

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE B-1: Concrete Breakout Strength of Anchors in Shear Octagon "Weak Anchors"

Approximate solution

c1= Do /2 - AC/2 Calculate D o so that equivalent circle has same area as octagon. Note: Area of octagon = 0.828D

2

For input into PIP STE05121 Anchor Bolt Design Spreadsheet, available to PIP Members only. c1 =1.03D/2 - AC/2

π Do2/4 = 0.828D2

c2, c4 = [(1.03D/2)2-(AC/2)2]1/2

π Do2 = 0.828D2(4) 0.828D2(4)

Av = 1.5c1D

Do =

π

Av (max) = n 4.5c12 = 1.03D

Pythagorean theorem:

c22 + (AC/2)2 = (Do/2)2

n = Total number of bolts = 12 Failure planes overlap each other to go clear across pedestal. Av = 1.5c1D (Max. Av = nAvo = n4.5c12)

c2 =[(1.03D/2)2 - (AC/2)2] 1/2

Process Industry Practices

Page A-6

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE B-2: Concrete Breakout Strength of Anchors in Shear Octagon "Strong" Anchors

c1 will vary with the number of anchors considred. Only anchors with an edge distance, c1, greater than or equal to the c 1 for the chosen bolt shall be used for resisting shear. For the case shown above, if the dimension marked c1 is chosen, n = 6 bolts. If the dimension marked c1 (ALT) is chosen, n = 4 bolts. For input into PIP STE05121 Anchor Bolt Design Spreadsheet , available to PIP Members only. c1 =As shown above c2 = (D-AC)/2 Av = 1.5c1 D Av (max) = n 4.5c12 n=6

Process Industry Practices

Alternate c1 (ALT) =As shown above c2 (ALT) = (D-Cos(45ο)AC)/2 Av = 1.5c1(ALT) D Av (max) = n 4.5(c1(ALT))2 n=4

Page A-7

PIP STE05121 Anchor Design Guide

January 2003

(h ef /3 Ma x.) X

FIGURE C-1: Tensile Reinforcement - Vertical Dowels

c1 or c 2

VERTICAL DOWELS

EDGE DIST. (Centerline of Anchor Bolt to Centerline of Dowel = (W /2 + X + (d /2)) rb h

PLAN db

(min.) (min.)

do

ld

ds

ld

hef

ha

C

T.O. CONC.

1.5 1

Wh X (hef /3 max.)

DOWEL TO MAT

NOTE: Refer to Section 7.3

SECTION Required Anchor Embedment, hef = l + C + (X + d /2) /1.5 d b

Refer to Table 3 for ld

Process Industry Practices

Page A-8

PIP STE05121 Anchor Design Guide

January 2003

FIGURE C-2: Tensile Reinforcement - Vertical Hairpin

HAIRPIN REINFORCEMENT X (hef /3 max.)

PLAN T.O. CONC.

l dh

(min.) (min.)

do

Wh X (hef /3 max.)

1.5

ld

h ef

1

HAIRPIN REINFORCEMENT

SECTION

Refer to Table 3 for ldhand ld.

Process Industry Practices

Page A-9

PIP STE05121 Anchor Bolt Design Guide

January 2003

ld

EDGE DISTANCE 5 do (min.)

FACE OF CONCRETE

180 DEG. STD. HOOK DIMENSION

FIGURE D-1: Shear Reinforcement - Horizontal Hairpin

ANCHOR HAIRPIN REINFORCEMENT

PLAN

EDGE DISTANCE 5 do (min.)

ld ANCHOR

MINIMUM COVER

SHEAR DIRECTION

HAIRPIN REINFORCEMENT

SECTION

Refer to Table 3 for l d .

Process Industry Practices

Page A-10

PIP STE05121 Anchor Bolt Design Guide

January 2003

EDGE DISTANCE 5 do (min.)

FACE OF CONCRETE

180 DEG. STD. HOOK DIMENSION

FIGURE D-2: Shear Reinforcement - Closed Ties

WEAK ANCHOR

STRONG ANCHOR HAIRPIN REINFORCEMENT

EDGE DISTANCE 5 do (min.)

FACE OF CONCRETE

180 DEG. STD. HOOK DIMENSION

PLAN

WEAK ANCHOR

STRONG ANCHOR CLOSED TIE REINFORCEMENT

EDGE DISTANCE 5 do (min.)

SHEAR DIRECTION ANCHOR

ANCHOR

MINIMUM

PLAN

CLOSED TIE REINFORCEMENT

SECTION

Process Industry Practices

Page A-11

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE D-3: Shear Reinforcement - Anchored Reinforcement

SHEAR DIRECTION

SHEAR DIRECTION

ANCHOR

ANCHOR

ld

ld ANCHOR ANGLE

1.5

Z

l d

Z

ANCHOR PLATE

1.5

ANCHORED REINFORCEMENT

1

1

LINE AT SURFACE OF HALF-PYRAMID INTERSECTING HAIRPIN

SECTION EDGE DIST.

ANCHOR

FACE OF CONCRETE

ld ANCHORED REINFORCEMENT

ANCHORED REINFORCEMENT

ANCHORED REINFORCEMENT (ALTERNATE) LINE AT SURFACE OF HALF-PYRAMID INTERSECTING HAIRPIN

SECTION ld = development length of reinforcement z = vertical hairpin concrete cover + 0.5d b

FAILURE HALF-PYRAMID 1.5

LINE AT SURFACE OF HALF-PYRAMID INTERSECTING HAIRPIN

1

PLAN

Note: 1. See Table 2 for rebar capacities. 2. Anchor plate or anchor angle must be designed for load from anchor. 3. Taking ld from centerline of bolt is conservative.

Process Industry Practices

Page A-12

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE D-4: Shear Reinforcement - Shear Angles

EDGE DISTANCE 5do (min.)

ANCHOR

FACE OF CONCRETE

1

1

FAILURE HALF-TRUNCATED PYRAMID

PLAN SHEAR DIRECTION EDGE DISTANCE 5d (min.) o

ANCHOR TACK WELD

FAILURE HALF-TRUNCATED PYRAMID

SECTION NOTE: DEDUCT AREA OF THE BEARING SURFACE OF SHEAR ANGLE IN CALCULATING A p (THE PROJECTION OF THE FAILURE HALF-TRUNCATED PYRAMID).

Process Industry Practices

Page A-13

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE D-5: Shear Reinforcement - Strut-and-Tie Model

VERTICAL REBAR

TIE T2 C1

ANCHOR BOLT

T1 25° M I N.

T1

C1

25° M I N.

T3

NOTES: 1. C1 AND C2 ARE COMPRESSION FORCES. 2. T1 , T2, AND T3 ARE TENSION FORCES. 3. ACTUAL FORCES WILL VARY WITH GEOMETRY.

Process Industry Practices

Page A-14

PIP STE05121 Anchor Bolt Design Guide

January 2003

2" (OR LESS)

4"

1 1/2"

FIGURE E: Minimum Lateral Reinforcement - Pedestal

Process Industry Practices

PROVIDE THIS ADDITIONAL TIE IN HIGH-SEISMIC AREAS OR IF SHEAR LUG IS USED

Page A-15

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE F: Coefficients of Friction

CONCRETE SURFACE

GROUT = 0.90

CONCRETE SURFACE

GROUT = 0.70 GROUT CONCRETE SURFACE

= 0.55

Process Industry Practices

Page A-16

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE G: Pretensioned Anchors for Turbines and Reciprocating Compressors

Notes:

GROUT

T0P OF DUCT TAPE BOTTOM OF GROUT 1/2

TOP NUT WASHER

Nuts: ASTM A563 Grade A heavy hex

BOTTOM OF DUCT TAPE

ANCHOR ROD

FILL WITH ELASTOMERIC MOLDABLE NON-HARDENING MATERIAL

PIPE SLEEVE do

FDN.

T

NUT 1

NUT 2 NUT 3

Washer: ASTM F436 Pipe sleeve: ASTM A53 SCH 40 2. Weld shall be inaccordance with AWS D1.1 . 3. Fabrication Sequence: A. Position anchor rod to obtain the specified projection above the anchor plate. B. Holding nut 1, tighten nut 2 to a snug tight condition. C. Hold nut 2, tighten nut 3 to a snug tight condition.

4d o+ T

ANCHOR PLATE

Anchor plate: ASTM A36 Anchor rod: ASTM A36 or F1554 GR 36.

1

DUCT TAPE

1. Materials:

D. Position and weld the pipe sleeve.

DIMENSIONS ARE IN INCHES

ANCHOR ROD

NOMINAL PIPE SLEEVE

ANCHOR PLATE DIMENSIONS

ANCHOR PLATE THICKNESS (T)

(in.)

(in.)

(in.)

(in.)

3/4

1-1/2

2 1/2 x 2 1/2

5/8

7/8

2

3x3

7/8

1

2

3x3

7/8

1-1/8

2-1/2

3 1/2 x 3 1/2

1

1-1/4

2-1/2

3 1/2 x 3 1/2

1

1-1/2

3

4 1/2 x 4 1/2

1 1/4

1-3/4

3-1/2

5x5

1 1/2

2

4

5 1/2 x 5 1/2

1 3/4

2-1/4

5

6 1/2 x 6 1/2

2

2-1/2

5

7x7

2 1/4

2-3/4

5

7x7

2 1/4

3

6

8x8

2 1/2

Process Industry Practices

Page A-17

PIP STE05121 Anchor Bolt Design Guide

January 2003

FIGURE H: Anchor-Tightening Sequence

1 12

5 9

8

4

3

7

10 TIGHTENING SEQUENCE

EQUIPMENT

6

11 2 EQUIPMENT

Process Industry Practices

Page A-18

PIP STE05121 Anchor Bolt Design Guide

January 2003

EXAMPLE 1 - Column Plate Connection Using Anchor Bolt Design Spreadsheet Base Plate Connection Data W12 x 45 column Four anchors on 6" x 16" spacing Base plate 1 1/2" x 14" x 1'-10" with vertical stiffener plates Factored base loads (gravity plus wind - maximum uplift condition) Shear (V u) = 17 kips Moment (M u) = 146 kip-feet Tension (N u) = 17 kips Low-seismic area (ductility not required) f'c = 3000 psi, A36 anchor material ΣMP = 0 Nu

Mu

T = (146 k-ft x 12 + 17 k x 8.625")/(11 + 8 - 2.67) ANCHOR BOLT TOP OF PED.

Vu

T = 116 k for 2 bolts P = 116 - 17 = 99 kips Resisting friction load (Vf) = m P

8"

11"

T

x P

m = 0.55 (PIP STE05121 - Figure F) Vf = 0.55 x 99 = 54 kips > 17 kips Therefore, anchors are not required to resist shear.

X = 2.67 (Refer to Blodgett - Design of Welded Structures - Figure 17 [Similar].) Note: Other theorys for determining "X" are equally valid. By trial and error using the Anchor Bolt Design Spreadsheet , available to PIP Member Companies only, the following is determined. (This takes only a few minutes.) Nom. Anchor Diameter = 1 3/4" Anchor Embedment = 21" (12 anchor diameters) Pedestal Size = 6' 4" x 5' 2" (c 1 = 30", c2 = 28", c3 = 46", c4 = 28", s2 = 6", s1 = 0") (Because only two bolts resist tension, s 1 must be input as 0".) The Anchor Bolt Design Spreadsheet input and output sheets are attached for this condition. This is a very large pedestal. If a smaller pedestal is required or desired, supplementary tensile reinforcing can be used to resist the load. See Example 2.

Process Industry Practices

Page A-19

Anchor Bolt Design Spreadsheet Input

January 03

PIP STE05121

PIP

Company

Project # PIP STE05121

Project

Example 1 - Column Plate Connection Using Anchor Bolt Design Spreadsheet

Name

Date

Checked by

Check Date

12/12/2002

LOADING CONDITIONS

Ductility required?

1

Factored shear load (kips) = V u =

perpendicular to edge

Is there a built-up grout pad?

116

3000

0

Cracking modification factor,Ψ 7

1.4 - Located in region where there isn't cracking at service loads (ft < fr)

No

1 3/4

CONCRETE FAILURE AREAS

No no

Do you want to manually input the value of An?

200

An=

3813 No no

Do you want to manually input the value of Av?

1.5c1 1.5c1

35

Av =

2000

Av=

2790

o

VU (perpendicular) VU (parallel)

Breakout cone for shear

TENSION Edge Distance, in. c1 = 30.0

c3 =

c2 = 28.0

c4 =

SHEAR Spacing, in.

46.0

s1 =

28.0

s2 =

Edge Distance, in.

0.0

c1 =

30.0

6.0

c2 =

28.0

c4 =

28.0

c1 = minimum edge distance c2 = least edge distance perpendicular to c 1

c1

INTERACTION OF TENSILE AND SHEAR FORCES

φNn = 117.3 kips

>=

Nu

Spacing, in. s2 =

6.0

c1 = edge distance in direction of V n (perp.) c2 = least edge distance perpendicular to c 1

c1 s1 c3 c2 s2 c4

c1 NU

(0=single anchor)

EDGE DISTANCES AND SPACING

An =

VU

h or 1.5c1

Thickness of member in which anchor is anchored, (in.) = h Number of anchors in tension = n (tension) = Number of anchors in shear = n (shear) =

Note: Units for An and Av are sq. in.

No

Adequate reinforcement provided to resist shear loads in anchors? 21.00 = hef ECCENTRICITY 60.00 = h Eccentricity of tensile force on group of tensile anchors (in.) 2 eN' = 0 4 Eccentricity of shear force on group of anchors (in.) (Note ev' must be less than s perpendicular to shear) eV'= 0

Effective anchor embedment depth (in.) = hef

Breakout cone for tension SUMMARY OF RESULTS DUCTILITY

No

Adequate supplementary reinf. provided to resist tension loads in anchors?

A36, Fu = 58

Nominal anchor diameter (in.) =

hef

Shear No

ANCHOR DATA, EMBEDMENT, AND THICKNESS OF MEMBER

1.5hef

No

Specified concrete strength (psi) = f' c =

Yes

Anchor material type =

Tension

Intermediate or high seismic risk?

Section 9.2

Nu and Vu were factored using factors from ACI 318-02? Factored tensile load (kips) = N u =

35o

1

Total Sheets

DESIGN CONSIDERATIONS

Note: Calculations are per ACI 318-02 Appendix D.

1.5hef

Sheet Number

c2 s2 c4

Subject

VU

c1 c4

s2

c2

RESULTS

= 116.0 kips

φVn = 75.6 kips >= Vu = 0.0 kips Nu/(φNn) + Vu/(φVn) = 0.99 + 0.00 = 0.99