STE05121 - Anchor Bolt Design Guide

TECHNICAL CORRECTIONOctober 2003

Process Industry PracticesStructural

PIP STE05121Anchor Bolt Design Guide

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice hasbeen prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing thesetechnical requirements into a single set of Practices, administrative, application, andengineering costs to both the purchaser and the manufacturer should be reduced. Whilethis Practice is expected to incorporate the majority of requirements of most users,individual applications may involve requirements that will be appended to and takeprecedence over this Practice. Determinations concerning fitness for purpose andparticular matters or application of the Practice to particular project or engineeringsituations should not be made solely on information contained in these materials. Theuse of trade names from time to time should not be viewed as an expression ofpreference but rather recognized as normal usage in the trade. Other brands having thesame specifications are equally correct and may be substituted for those named. AllPractices or guidelines are intended to be consistent with applicable laws andregulations including OSHA requirements. To the extent these Practices or guidelinesshould conflict with OSHA or other applicable laws or regulations, such laws orregulations must be followed. Consult an appropriate professional before applying oracting on any material contained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Team andwill 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 This Practice will be revised, reaffirmed, or withdrawn.Information on whether this Practice has been revised may be found at www.pip.org.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, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

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

PRINTING HISTORY

January 2003 IssuedOctober 2003 Technical Correction

Not printed with State funds


Process Industry Practices Page 1 of 25

Process Industry PracticesStructural


Table of Contents

1. Introduction..................................31.1 Purpose ............................................. 31.2 Scope................................................. 31.3 Use of Shall and Should ............... 31.4 Dimensions ........................................ 3

2. References ...................................32.1 Process Industry Practices ................ 32.2 Industry Codes and Standards .......... 32.3 Government Regulations ................... 42.4 Other References .............................. 5

3. Notation.......................................5

4. Materials......................................74.1 Anchors.............................................. 74.2 Sleeves .............................................. 84.3 Washers ............................................ 84.4 Corrosion ........................................... 9

5. Strength Design........................105.1 Loading ............................................ 105.2 Anchor Bolt Design Spreadsheet..... 105.3 Anchor Design Considerations ........ 105.4 Shear Strength of Anchors in a

Rectangular Pattern......................... 11

5.5 Shear Strength of Anchors in aCircular Pattern................................ 11

5.6 Minimum Dimensions ...................... 11

6. Ductile Design .......................... 136.1 Ductile Design Philosophy ............... 136.2 Critical Areas Requiring Ductile

Design.............................................. 136.3 Requirements for Ductile Design..... 136.4 Means to Achieve Ductile Design .... 14

7. Reinforcing Design .................. 157.1 General ............................................ 157.2 Failure Surface ................................ 157.3 Reinforcing Design to Transfer

Tensile Forces ................................. 167.4 Reinforcing to Transfer

Shear Forces ................................... 17

8. Frictional Resistance ............... 178.1 General ............................................ 178.2 Calculating Resisting

Friction Force................................... 18

9. Shear Lug Design..................... 189.1 Calculating Shear Load Applied to

Shear Lug ........................................ 199.2 Design Procedure for

Shear Lug Plate ............................... 19

PIP STE05121 TECHNICAL CORRECTIONAnchor Bolt Design Guide October 2003

Page 2 of 25 Process Industry Practices

9.3 Design Procedure forShear Lug Pipe Section....................19

10.Pretensioning............................2010.1 Advantages ......................................2110.2 Disadvantages..................................2110.3 When to Apply Pretensioning...........2110.4 Concrete Failure...............................2110.5 Stretching Length .............................2210.6 Pretensioning Methods.....................2210.7 Relaxation ........................................2310.8 Tightening Sequence .......................2410.9 Recommended Tightening if Anchor

Pretensioning Is Not Required .........24

Figures, Tables, and Examples.....25

Tables1. Minimum Anchor Dimensions ........A-12. Reinforcement Tensile Capacity

and Development Length ..............A-23. Hairpin Reinforcement Design and

Details ............................................A-34. Pretension Load and Torque

Recommendations .........................A-4

FiguresA. Anchor Details ................................A-5B-1. Concrete Breakout Strength of

Anchors in Shear Octagon Weak Anchors...............A-6

B-2. Concrete Breakout Strength ofAnchors 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-16G. Pretensioned Anchors for Turbines

and Reciprocating Compressors..A-17H. Anchor-Tightening Sequence.......A-18

Examples1. Column Plate Connection Using

Anchor Bolt DesignSpreadsheet ................................. A-19

2. Column Plate Connection Supplementary TensileReinforcing ................................... A-23

3. Shear Lug Plate Section Design .. A-244. Shear Lug Pipe Section Design ... A-26

TECHNICAL CORRECTION PIP STE05121October 2003 Anchor Bolt Design Guide


1. Introduction

1.1 PurposeThis Practice provides the engineer and designer with guidelines for anchordesign for use by the process industry companies and engineering/constructionfirms.

1.2 ScopeThis design guide defines the minimum requirements for the design of anchors inprocess 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 ShouldThroughout 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 agood practice.

1.4 DimensionsAt the time of issue of this Practice, a metric version of the basic reference forAnchor Bolt Design, ACI 318, had not been developed; therefore this Practicewas 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 beused, 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.]



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 PracticalAspects 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, Zinc-

Coated, 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 BoltReport.]

ASCE 7-2002 - Minimum Design Loads for Buildings and OtherStructures

American Welding Society AWS D1.1 - Structural Welding Code - Steel

International Code Council (ICC) International Building Code (IBC)

2.3 Government RegulationsFederal Standards and Instructions of the Occupational Safety and HealthAdministration (OSHA), including any additional requirements by state or localagencies 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



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, andexamples as kips and ksi, respectively. Where this is done, the units will alwaysbe shown.

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

AVo = Projected concrete failure area of one anchor, for calculation of strength inshear, 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 onedirection, inches. Where shear force is applied to the anchor, c1 is in thedirection of the shear force.

c2 = Distance from the center of an anchor shaft to the edge of the concrete in thedirection 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

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

fut = Anchor material minimum specified tensile strength, psi



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



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

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

= Concrete strength reduction factor (This value varies; refer to text for value.)b = Steel resistance factor for flexurev = Steel resistance factor for shear7 = Modification factor, for strength in shear, to account for cracking, as defined in

ACI 318-02, paragraph D.6.2.7

= Coefficient of friction

4. Materials

4.1 AnchorsRefer to the ASCE Anchor Bolt Report, chapter 2, for a description of andspecifications for common materials for anchors. Unless a special corrosiveenvironment 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 F1554grade 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 F1554grade 55 rods are specified, add the weldability supplement.



Properties for Recommended Anchor Materials

Anchor Material TypeFyksi

futksi Ductile?

A307 Not clearlydefined

60 Yes

A36 or F1554 grade 36 36 58 YesF1554 grade 55 55 75 YesF1554 grade 105 105 125 Yes

do 2.5" 105 125 Yes

2.5" < do 4"

95 115 Yes

A193 grade B7Based on boltdiameter (db)(used for high-temperatureservice)

4" < do 7"

75 100 Yes

A354 grade BC 109 125 Yes

A354 grade BD 130 150 Yes

1/4" < do 1"

92 120 Yes

1" < do 1.5"

81 105 Yes

A449Based on boltdiameter (db)

1.5" < do 3"

58 90 Yes

4.2 SleevesAnchors should be installed with sleeves when small movement of the bolt isdesired after the bolt is set in concrete. The two most common examples follow:

a. When precise alignment of anchors is required during installation ofstructural columns or equipment. In this situation, the sleeve should befilled with grout after installation is complete.

b. When anchors will be pretensioned to maintain the bolt under continuoustensile stresses during load reversal. Pretensioning requires the bolt surfaceto be free; therefore, the top of these sleeves should be sealed or the sleeveshould be filled with elastomeric material to prevent grout or water fromfilling the sleeve.

Two types of sleeves are commonly used with anchors. A partial sleeve isprimarily used for alignment requirements, whereas the full sleeve is used foralignment as well as for pretensioning. Sleeves do not affect the design of aheaded anchor for tensile loading because the tension in the anchor is transferredto the concrete through the head, not the anchorconcrete bond. Sleeved anchorscan resist shear forces only when the sleeve is filled with grout.

Refer to PIP REIE686 for use of sleeves with anchor bolts in machineryfoundations.

For concrete cover requirements, refer to section 5.6.4 of this Practice.

4.3 WashersWashers 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.



The following table shows the PIP-recommended base plate hole diameter. Thehole in the washer should be equal to the bolt diameter plus 1/16 inch.

Recommended Base Plate Hole and Washer Size

Anchor BoltDia.

(Inches)

PIP-RecommendedBase Plate Hole

Diameter*

OutsideWasher Dia.

(Inches)1/2 13/16 1-5/85/8 15/16 1-3/43/4 1-1/16 1-7/87/8 1-3/16 2-1/41 1-1/2 2 5/8

1-1/4 1-3/4 2-7/81-1/2 2 3-1/81-3/4 2-1/4 3-3/4

2 3 4-1/22-1/4 3-1/4 4-3/42-1/2 3-1/2 52-3/4 3-3/4 5-1/43-1/2 4 5-1/2

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

4.4 CorrosionCorrosion of an anchor can seriously affect the strength and design life of theanchor. When deciding which anchor material to use or what precaution to takeagainst 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 andASTM F1554 grade 36 threaded rods. Stainless steel anchors are a costly optionbut may be required in some environments. Painting or coating the anchor willprotect the anchor, but more maintenance may be required.



To reduce the amount of contact with corrosive substances, pier design andanchor arrangement should consider water collection and anchor environment.

If the engineer determines that prolonged contact with a corrosive substance isunavoidable, a metallurgist should be consulted to determine alternate anchormaterials or protective options.

5. Strength Design

Strength design, which utilizes factored loads, shall be in accordance with Appendix Dof ACI 318-02. In this Practice, strength design will apply to headed bolts and headedstud 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 embeddedmore than 25 inches (shown in ACI 318-02, D.2.2) may be ignored; however onlyequation D-7 (not equation D-8) shall be used for checking the breakout strength incracked concrete.

ACI 318-02, D.6.2.7, states that for anchors located in a region of a concrete memberwhere analysis indicates no cracking at service loads, the modification factor, 7, shall beequal to 1.4. The tops of pedestals are normally outside cracked regions; therefore 7should be 1.4 for most pedestals. For anchors at beams and slabs, follow the guidelinesof ACI 318-02, section D.6.2.7.

5.1 LoadingAnchors shall be designed for the factored load combinations in accordance withACI 318-02, section 9.2 or Appendix C. Care shall be taken to assure that theproper strength reduction factor, , is used. That is, if the load combinations insection 9.2 are used, then use the s from section 9.2; if the load combinationsfrom Appendix C are used, then use the 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 Dof ACI 318-02 and this Practice. (The spreadsheet, which is available to PIPMember Companies only, not to PIP Subscribers, can be accessed viahttp://www.pip.org/members/irc/ under Tools.) The spreadsheet gives shearand 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 configurationis ductile (refer to section 6, this Practice). The user needs to use the spreadsheetin combination with Appendix D of ACI 318-02 and this Practice. Thespreadsheet merely saves the user time in laborious calculations but is nosubstitute for the engineers knowledge and expertise. See Appendix Example 1(this Practice) for an illustration of the use of the Anchor Bolt DesignSpreadsheet.

5.3 Anchor Design ConsiderationsTo accommodate reasonable misalignment in setting the anchor bolts, baseplates are usually provided with oversized holes. If the factored shear loads



exceed the values that can be resisted by friction between the base plate and thegrout (see sections 8 and 9), a suitable means must be provided to transfer theshear from the base plate to the foundation. This can be accomplished by thefollowing:

a. Either shear lugs are used, or

b. A mechanism to transfer load from the base plate to the bolt withoutslippage is incorporated (such as welding washers in place).

If no tensile force is applied to the anchors, the anchors need not be designed fortension. Where the tensile force is adequately transferred to properly designedrebar, there is no requirement to check for concrete breakout strength of theanchor or anchors in tension (Ncb or Ncbg). Refer to section 7.3.

5.4 Shear Strength of Anchors in a Rectangular PatternIn accordance with ACI 318, the concrete design shear strength of a group ofanchors 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 perpendicularto the direction of force on the anchors

b. The design strength of the row of anchors furthest from the edge if theanchors are welded to the attachment so as to distribute the force to allanchors

c. Although not specifically accepted in ACI 318, the design strength of thefurthest row, if closed shear ties or other mechanisms transfer the load tothe row of anchors furthest from the edge. Refer to Figure D-2.

5.5 Shear Strength of Anchors in a Circular PatternAnchor bolts for tall, vertical vessels are frequently not required to resist shear.The shear is resisted by friction created by the large compressive forcesattributable to overturning. However anchor bolts for shorter horizontal vesselsmay be required to resist shear. Following are two alternative methods fordesigning the anchors to resist shear:

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

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

5.6 Minimum DimensionsMinimum edge distance and anchor spacing shall be in accordance with ACI 318and should be in accordance with ASCE recommendations. Minimumembedment should be in accordance with the recommendations of the ASCEAnchor Bolt Report. Refer to Table 1 and Figure A of this Practice. (Ifsupplementary reinforcement is added to control splitting or the anchor size is



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

5.6.1 Edge Distancea. ACI 318 requires cast-in headed anchors that will be torqued to

have minimum edge distances of 6do. Otherwise, the onlyrequirement for edge distance is that at least the same cover bepresent 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 Reportrecommends a minimum edge distance of 4do for ASTM A307 orASTM A36 bolts or their equivalent and 6do for high-strength bolts.

c. According to PIP REIE686, the recommended edge distance foranchor bolts in machinery foundations is 4do, 6 inches minimum.

5.6.2 Embedment DepthNo minimum embedment depth is specified in ACI 318 as long as theeffective embedment depth is enough to resist uplift forces. If ductility isrequired, greater embedment may be necessary. The ASCE Anchor BoltReport recommends a minimum embedment depth of 12 diameters.

hef = 12do5.6.3 Spacing between Anchors

ACI 318 requires the minimum spacing between anchors to be at least4do for untorqued cast-in anchors and 6do for torqued anchors.

5.6.4 Modification for SleevesWhere anchor sleeves are used, the preceding minimum dimensionsshould be modified as follows:

a. Edge distance should be increased by an amount equal to half thesleeve diameter minus half the anchor diameter, 0.5(ds do).

b. Embedment length for anchors equal to or greater than 1 inchshould not be less than the larger of 12 anchor diameters (12do) orthe sleeve length plus 6 anchor diameters (sleeve length + 6do).For anchors less than 1 inch in diameter, the embedment lengthshould not be less than the sleeve length plus 6 inches.

c. Spacing between anchors should be increased by an amount equalto the difference between the sleeve diameter and the anchordiameter: s 4do + (ds do) for A307/A36 anchors or theirequivalent.

5.6.5 Modification for Anchor Bottom PlateIf a plate is used at the bottom of the anchor, similar to that shown inFigure G, the edge distance should be increased by half of the plate



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

5.6.6 Anchor ProjectionAnchor bolts should project a minimum of two threads above the fullyengaged nut(s).

6. Ductile Design

6.1 Ductile Design PhilosophyA ductile anchorage design can be defined as one in which the yielding of theanchor (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 ofcapacity of the system resulting from a brittle failure of the concrete (ASCEAnchor Bolt Report).

Anchors embedded in concrete and pulled to failure fail either by pullout of theconcrete cone or by tensile failure of the anchor itself. The former is a brittlefailure and the latter is a ductile failure. A brittle failure occurs suddenly andwithout warning, possibly causing catastrophic tragedies. In contrast, a ductilefailure will cause the steel to yield, elongate gradually, and absorb a significantamount of energy, often preventing structures from collapsing. Consequently,when the design of a structure is based upon ductility or energy absorption, oneof the following mechanisms for ductility shall be used.

6.1.1 Anchors shall be designed to be governed by tensile or shear strength ofthe 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 theanchor to the structure shall be designed so that the attachment willundergo ductile yielding at a load level no greater than 75 percent of theminimum anchor design strength.

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

6.2 Critical Areas Requiring Ductile DesignAnchors designed to resist critical loads, where magnitudes cannot be preciselyquantified (e.g., where design is based upon energy absorption), shall bedesigned using the requirements for ductile design. Examples are anchors inareas of intermediate or high seismicity and anchors used for blast loadresistance.

6.3 Requirements for Ductile DesignIf the mechanism described in section 6.1.1 is used, the ductile design isachieved when the anchoring capacity of the concrete is greater than that of theanchor in tension, in shear, or in a combination of both. This is a strengthrequirement and is independent of the magnitudes of the applied loads. If it can



be shown that failure that is due to tensile loads will occur before failure that isdue to shear loads, then the anchor need only be ductile for tensile loads. (Thereverse 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 0.75Ns and 0.75Vs. In addition, make sure that the steel chosenis ductile steel as listed in section 4.1. The engineer will need to do the followingcalculations manually, using Appendix D of ACI 318-02.

Comment: For PIP Member Companies, the loads and size can then beentered into the Anchor Bolt Design Spreadsheet, described insection 5.2, to check the second and third steps (next twoparagraphs).

The second step is to ensure that the concrete pullout capacities (concretebreakout strength in tension, pullout strength of anchor in tension, and concreteside-face blowout strength) are greater than the tensile steel capacity of theanchor:

Ncb or Ncbg > Ns, Npn > Ns, and Nsb or Nsbg > NsThe third step is to ensure that the concrete shear capacities (concrete breakoutstrength in shear and concrete pryout strength in shear) are greater than the steelshear capacity of the anchor:

Vcb or Vcbg > Vs and Vcp > VsIn lieu of the preceding requirements, the attachment to the structure that isconnected by the anchor to the foundation may be designed so that theattachment will undergo ductile yielding at a load level no greater than75 percent of the minimum anchor design strength.

6.4 Means to Achieve Ductile DesignIf conditions as specified in section 6.3 cannot be met, the concrete capacity canbe increased to achieve a ductile design using the following:

6.4.1 Increased Concrete Tensile CapacityConcrete 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 inpedestals, 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 CapacityConcrete shear capacity can be increased by the following:



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 carrythe entire shear. If this method is used, do not consider any contributionfrom concrete shear strength. Refer to section 7.4.

Another alternative is the use of a shear lug. Refer to section 9. If thisalternative is chosen, either the following item a or item b must beadhered:

a. The shear lug needs to be designed to undergo ductile yieldingbefore failure of the concrete.

b. The attachment that the shear lug connects to must undergo ductileyielding at a load level no greater that 75 percent of the minimumshear lug design strength.

7. Reinforcing Design

7.1 GeneralWhen anchor embedment or edge distances are not sufficient to prevent concretefailure that is due to factored loads, or for a ductile type connection, if Ncb orNcbg < Ns or Vcb or Vcbg < Vs, then reinforcing steel may be used toprevent concrete failure.

The reinforcing needed to develop the required anchor strength shall be designedin accordance with ACI 318 and the following.

7.2 Failure SurfaceReinforcement shall be fully developed for the required load on both sides of thefailure surfaces resulting from tensile or shear forces. Development lengths andreinforcement covers shall be in accordance with ACI 318.

7.2.1 The failure surface resulting from the applied tension load shall be oneof the following:

a. For a single bolt, the failure surface is that of a pyramid, with thedepth equal to the embedded depth of the anchor (hef) and the basebeing a square with each side equal to three times the embeddeddepth (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 isformed by a line radiating at a 1.5-to-1 slope from the bearing edgeof the anchor group, edge of nuts, toward the surface from whichthe anchors protrude. (Refer to Figure RD.5.2.1(b) of ACI 318-02.)



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

7.3 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)/fyObtain hef, the embedment depth of the anchor as follows: (Refer toFigure C-1.)

hef = ld + C + (X + db/2)/1.5

a. Calculate ld, the development length of the reinforcing barsresisting the load, using ACI 318. Note that the number of bars canbe increased and the size of the reinforcing bars can be decreased toreduce the development length when required.

b. Add C, the concrete cover over the top of reinforcing bars to thefinished surface.

c. Add X, the clear distance from the anchor nut to the reinforcingbars.

d. Add db/2, half the diameter of the reinforcing bars.

Note that the reinforcing bars were probably sized during pedestaldesign. If more reinforcement is required by the pedestal design thanrequired by the anchor load transfer, the reinforcing bar developmentlength may be reduced by multiplying by the ratio of the reinforcing bararea 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, andcannot be applied in areas of moderate or high seismic risk.

7.3.2 Direct tensile loads can be transferred effectively by the use of hairpinreinforcement or vertical dowels according to the following guidelines:

a. Hairpin legs and vertical dowels shall be located within hef/3from the edge of the anchor head.

b. Hairpin legs and dowels shall extend a minimum of ld, beyondthe potential failure plane, or additional rebar area shall beprovided to reduce the required embedment length (seesection 7.3.1).



c. Where tension reinforcement is designed, it should be designed tocarry the entire tension force, excluding any contribution from theconcrete.

d. For an example design calculation using hairpins, see AppendixExample 2 (this Practice).

7.4 Reinforcing to Transfer Shear Forces7.4.1 Several shear reinforcement configurations or assemblies can be

considered effective to prevent failure of the concrete. Depending on theparticular situation, one of the following types of shear reinforcementcan 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 andFigure D-5 of this Practice.)

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

7.4.3 Where shear reinforcing is designed, it should be designed to carry theentire 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 requiredwithin 5 inches of the top of each pedestal. Refer to Figure E. Use ofthree ties is recommended near the top of each pedestal if shear lugs areused or if the pedestals are located in areas of moderate or high seismicrisk.

8. Frictional Resistance

8.1 GeneralWhere allowed by code, anchors need not be designed for shear if it can beshown that the factored shear loads are transmitted through friction developedbetween the bottom of the base plate and the top of the concrete foundation. Ifthere is moment on a base plate, the moment may produce a downward load thatwill develop friction even when the column or vertical vessel is in uplift. Thisdownward load can be considered in calculating frictional resistance. Care shallbe taken to assure that the downward load that produces frictional resistanceoccurs simultaneously with the shear load. In resisting horizontal loads, thefriction resistance attributable to downward force from overturning moment maybe used.



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

Note: Before planning to weld the anchor nut to the base plate, the engineershould consult a welding specialist to determine whether this ispractical. Depending on the metallurgy of the nut, the welding mayrequire a special welding procedure.

8.2 Calculating Resisting Friction ForceThe resisting friction force, Vf, may be computed as follows:

Vf = PP = normal compression force

= coefficient of frictionThe materials used and the embedment depth of the base plate determine thevalue of the coefficient of friction. (Refer to Figure F for a pictorialrepresentation.)

a. = 0.90 for concrete placed against as-rolled steel with the contact plane afull plate thickness below the concrete surface.

b. = 0.70 for concrete or grout placed against as-rolled steel with thecontact plate coincidental with the concrete surface.

c. = 0.55 for grouted conditions with the contact plane between grout andas-rolled steel above the concrete surface.

9. Shear Lug Design

Normally, friction and the shear capacity of the anchors used in a foundation adequatelyresist column base shear forces. In some cases, however, the engineer may find the shearforce too great and may be required to transfer the excess shear force to the foundationby another means. If the total factored shear loads are transmitted through shear lugs orfriction, the anchor bolts need not be designed for shear.

A shear lug (a plate or pipe stub section, welded perpendicularly to the bottom of thebase plate) allows for complete transfer of the force through the shear lug, thus taking theshear load off of the anchors. The bearing on the shear lug is applied only on the portionof the lug adjacent to the concrete. Therefore, the engineer should disregard the portionof the lug immersed in the top layer of grout and uniformly distribute the bearing loadthrough the remaining height.

The shear lug should be designed for the applied shear portion not resisted by frictionbetween the base plate and concrete foundation. Grout must completely surround the lugplate or pipe section and must entirely fill the slot created in the concrete. When using apipe section, a hole approximately 2 inches in diameter should be drilled through the



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

9.1 Calculating Shear Load Applied to Shear LugThe applied shear load, Vapp, used to design the shear lug should be computed asfollows:

Vapp = Vu - Vf

9.2 Design Procedure for Shear Lug PlateDesign of a shear lug plate follows (for an example calculation, see AppendixExample 3, this Practice):

a. Calculate the required bearing area for the shear lug:

Areq = Vapp / (0.85 * * fc) = 0.65b. 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 lugwidth, on the basis of the known base plate size to find H, the total heightof the lug, including the grout thickness, G:

H = (Areq /W) + G

c. Calculate the factored cantilever end moment acting on a unit length of theshear lug:

Mu = (Vapp/W) * (G + (H-G)/2)

d. With the value for the moment, the lug thickness can be found. The shearlug 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 methodshown as follows is from ACI 349-01, Appendix B, section B.11:

Vcb = AV*4**[fc]0.5where

AV = the projected area of the failure half-truncated pyramid definedby projecting a 45-degree plane from the bearing edges of theshear lug to the free edge. The bearing area of the shear lugshall be excluded from the projected area.

= concrete strength reduction factor = 0.859.3 Design Procedure for Shear Lug Pipe Section

Design of a shear lug pipe section follows (for an example calculation, seeAppendix Example 4, this Practice):

a. Calculate the required bearing area for the shear lug:



Areq = Vapp /(0.85fc) = 0.60b. 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 thepipe section, based on the known base plate size to find H, the total heightof 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 sectionfailure (AISC LRFD Manual, pages 16.1-31 and 16.1-100).

Shear check

v Vn Vappwhere v = 0.9 and Vn = 0.6 Fy (D2 (D-2t)2)/4

Moment check

b Mn Muwhere b = 0.9 and Mn = the lesser of:

= S * [{600/(D/t)} + Fy] (local buckling moment)and

= Z * Fy (plastic moment)e. Design weld between pipe stub section and base plate.

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

10. Pretensioning

Pretensioning induces preset tensile stresses to anchor bolts before actual loads areapplied. When properly performed, pretensioning can reduce deflection, avoid stressreversal, and minimize vibration amplitude of dynamic machinery. Pretensioning may beconsidered 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 ofcreep and relaxation of the bolt material. AISC does not recommend pretensioninganchors. The AISC LRFD Manual paragraph C-A3.4 states, The designer should beaware that pretensioning anchor bolts is not recommended due to relaxation and stresscorrosion after pretensioning. AISC Steel Design Guide Series 1, anchor bolt sectionstates, Because of long-term relaxation of concrete, prestressing of anchor bolts isunreliable and hardly ever justified.



In practical applications, the engineer should decide whether to pretension the anchorbolt by considering the following advantages and disadvantages:

10.1 AdvantagesThe 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 orseismic load

d. Will increase the frictional shear resistance for process towers and otherequipment

10.2 DisadvantagesThe 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 andinstallation of pretensioned anchors. There is little research in this area.

c. Questionable nature about the long-term load on the anchor from creep ofconcrete 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 becauseduring pretensioning, the sleeve around the anchor typically is not filledwith grout.

f. Little assurance that the anchor is properly installed and pretensioned inthe field

g. Possible direct damage from pretensioning. The pretensioning itself candamage the concrete if not properly designed or if the pretension load isnot properly regulated.

10.3 When to Apply PretensioningPretensioning should be considered for vertical vessels that are more than150 feet tall or for those with height-to-width ratios of more than 10 and ifrecommended by the equipment manufacturer; pretensioning is required ifrequired for warrantee. When not otherwise specified, anchors for turbines andreciprocating compressors should be torqued to the values shown in Table 4.

10.4 Concrete FailureIn certain situations, the use of high-strength anchors in concrete with highpretension forces may exceed the ultimate capacity of the concrete byprematurely breaking out the concrete in the typical failure pyramid. Whetherthis 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 bedesigned so that the breakout strength of the anchor in tension is greater than themaximum pretension force applied to the anchor. In the case of a stiff base platecovering the concrete failure pyramid, the stresses induced by external uplift onthe 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 externaluplift exceeds the gravity plus pretensioning force loads.

10.5 Stretching LengthPrestressing should be implemented only when the stretching (spring) length ofthe anchor extends down near the anchor head of the anchor. On a typical anchorembedment, where there is no provision for a stretching length, if a prestressingload is applied to the anchor, the anchor starts to shed its load to the concretethrough its bond on the anchor. At that time, a high bond stress exists in the firstfew inches of embedment. This bond will relieve itself over time and therebyreduce the prestress load on the anchor. Therefore it is important to preventbonding between the anchor and concrete for pretensioned anchors. Refer toFigure G for a suggested detail.

10.6 Pretensioning MethodsMethods used to apply preload are as follows:

10.6.1 Hydraulic jacking: Hydraulic jacking is the most accurate method and isrecommended if the pretension load is essential to the integrity of thedesign. The anchor design should accommodate any physical clearanceand anchor projections required for the hydraulic equipment.

10.6.2 Torque wrench: Torque wrench pretensioning provides only a roughmeasure of actual pretension load but can be the method of choice if theamount of pretension load is not critical. Torque values are shown inTable 4.

10.6.3 Turn-of-nut: This method is the easiest to apply, but there are questionsas to the accuracy of the pretension load. The pretension load fromstretching the anchor can be closely determined, but accounting for thecompression of the concrete between the base plate and the nut at thebottom of the anchor is difficult. Per the ASCE Anchor Bolt Report, therequired amount of nut rotation from the snug tight condition toproduce a desired tensile stress in the bolt (ft) can be determined usingthe following formula.

Nut rotation in degrees = (360 l Ase ft Tlc) / (E Ad)

where:

l = bolt stretch length (the distance between the top and bottomnuts on the bolt)

Ase = tensile stress area of bolt

ft = desired tensile stress



Tlc = bolt threads per unit length

E = elastic modulus of bolt

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 tightcondition, and then turned the number of degrees originally specified.

10.6.4 Load indicator washers: This method is good if the amount of pretensiondesired is as much as the required load in slip-critical structural steelconnections. These loads are typically very high and not normallyrequired for anchors.

10.7 RelaxationAccording 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 thehighly stressed concrete under the anchor head. The final value of the tensionforce in the anchor depends primarily on the value of bearing stresses under thehead, the concrete deformation, and the anchorage depth. In typical cases thevalue 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 theanchors 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 byabout 30 percent by retensioning.



10.8 Tightening SequencePretensioned anchors should be tightened in two stages:

a. First stage should apply 50 percent of the full pretension load to allanchors.

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 RequiredAnchors should be brought to a snug, tight condition. This is defined as thetightness that exists after a few impacts from an impact wrench or the full effortof a man using a spud wrench. At this point all surfaces should be in full contact.



AppendixFigures, Tables, and Examples



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

hef

P1

do + 1/2"

(in.) (in.) 1/2 1.00 1.00 6.0 4.5 4.5 2.0 2 5 65/8 1.25 1.13 7.5 4.5 4.5 2.5 2 7 63/4 1.44 1.25 9.0 4.5 4.5 3.0 2 7 67/8 1.69 1.38 10.5 4.5 5.3 3.5 2 7 6

1 1.88 1.50 12.0 4.5 6.0 4.0 3 10 61-1/8 2.06 1.63 13.5 4.5 6.8 4.5 3 10 71-1/4 2.31 1.75 15.0 5.0 7.5 5.0 3 10 81-3/8 2.50 1.88 16.5 5.5 8.3 5.5 4 15 81-1/2 2.75 2.00 18.0 6.0 9.0 6.0 4 15 91-3/4 3.19 2.25 21.0 7.0 10.5 7.0 4 15 11 2 3.63 2.50 24.0 8.0 12.0 8.0 4 18 122-1/4 4.06 2.75 27.0 9.0 13.5 9.0 4 18 142-1/2 4.50 3.00 30.0 10.0 15.0 10.0 6 24 152-3/4 4.94 3.25 33.0 11.0 16.5 11.0 6 24 17 3 5.31 3.50 36.0 12.0 18.0 12.0 6 24 18

1IF 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)

2FOR MACHINERY FOUNDATIONS PIP REIE686 REQUIRES A MINIMUM EDGE DISTANCE OF 6 INCHES.

6do 6"Height hs

ANCHOR DIA. do

SHELL SIZE

4do

A307/A36 F1554

Grade 36

HIGH-STRENGTH

OR TORQUED

BOLTS

(in.) (in.) (in.) (in.) (in.)

12doWIDTH

Wh

6do 4.5"4do 4.5"

he'

Diameter ds

(in.) (in.) (in.)

HEAVY HEX

HEAD/ NUT

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

EDGE DISTANCE c2 SPACING

ANCH. TYPE 2

Process Industry Practices Page A-1



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, = 0.90 (ACI 318-02, Section 9.3)Reinforcement Location Factor, = 1.3 (Top Reinforcement), 1.0 (Other Reinforcement)Coating Factor, = 1.0 (Uncoated Reinforcement)Reinforcement Size Factor, = 0.8 ( #6 bar), 1.0 (> #6 bar)Lightweight Aggregate Concrete Factor, = 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] ()/[(c + Ktr)/db] [(c + Ktr)/db 2.5] (12-1)where c is the smaller of either the distance from the center of the bar to thenearest concrete surface or one-half the center-to-center spacing of the bars

BAR SIZE

BAR AREA

BAR CAPACITY

Ar *Ar*(fy)

TOP OTHER TOP OTHER

(sq. in.) (Kips) (in.) (in.) (in.) (in.) (in.) (in.)

#3 0.11 5.94 1:5/16 13 12 2:13/16 13 12#4 0.20 10.80 1:1/4 17 13 2:3/4 17 13#5 0.31 16.74 1:3/16 22 17 2:11/16 22 17#6 0.44 23.76 1:1/8 32 25 2:5/8 26 20#7 0.60 32.40 1:1/16 55 42 2:9/16 38 29#8 0.79 42.66 1 71 55 2:1/2 43 33#9 1.00 54.00 15/16 91 70 2:7/16 48 37

#10 1.27 68.58 7/8 115 89 2:3/8 58 44#11 1.56 84.24 13/16 142 109 2:5/16 71 55

#3 5:13/16 13 12#4 5:3/4 17 13#5 5:11/16 22 17#6 5:5/8 26 20#7 5:9/16 38 29#8 5:1/2 43 33#9 5:7/16 48 37

#10 5:3/8 55 42#11 5:5/16 61 47

SPACING 3.0 in. c = 1.5 in. SPACING 6.0 in. c = 3.0 in.

REQUIRED COVER

TENSION DEVELOPMENT LENGTH, ld

SPACING 12.0 in. c = 6.0 in.FACTORS FOR DIFFERENT VALUES OF f'c (Note: ld shall not be less than 12 inches.)

TENSION DEVELOPMENT LENGTH, ldREQUIRED

COVER

f'cDEVELOPMENT

LENGTH FACTOR3,000

5,0006,000

1.000.870.770.71

4,000




TABLE 3: Hairpin Reinforcement Design and Details

Reinforcement Yield Strength, fy = 60 ksiCompressive Strength of Concrete, f'c = 3,000 psi

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

#3 8.2 5.94 6.0 2.0 4.0 2.3 12 6.91 13 6.84#4 11.0 10.80 7.7 3.2 4.5 3.0 13 13.40 17 12.80#5 13.7 16.74 9.6 4.6 5.0 3.8 17 21.22 22 20.19#6 16.4 23.76 11.5 5.5 6.0 4.5 25 29.06 32 27.84#7 19.2 32.40 13.4 6.4 7.0 5.3 42 37.36 55 36.22#8 21.9 42.66 15.3 7.3 8.0 6.0 55 48.37 71 47.06#9 24.7 54.00 17.3 7.1 10.2 9.5 70 59.54 91 58.26

#10 27.8 68.58 19.5 8.0 11.4 10.8 89 74.83 115 73.39#11 30.9 84.24 21.6 8.9 12.7 12.0 109 91.15 142 89.56

(a)

lb remains the same.ldh = ldh*(D)

HAIRPIN CAPACITY: 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]

5,0006,000

0.770.71

3,0004,000

1.000.87

0.7*ldh

la lb

T (hairpin ) = T (hook) x (1+la/ld)

(kips)

ACI 12.5.1 & Fig. R12.5.1 (A

CI/

CR

SI)

ldh

REI

NFO

RC

EMEN

T

B

AR

SIZ

E

180 DEG HOOK DEVELOPMENT

LENGTH ldh =

(0.02fy/(f'c)0.5)db

(ACI 12.5.2 )

HAIRPIN AND HOOK DIMENSIONS

(in.)

REI

NFO

RC

ING

BA

R

CA

PAC

ITY

f*Ar*(fy)

CA

PAC

ITY

SEE

NO

TE (4

)

(in.) (in.) (in.) (in.) (in.) (kips)

INSIDE HOOK

OTHER BARS ld (a) (ACI

12.2.3)

VALUES OF f'c:

f'c Development Length Factor (D)

VERTICAL AND HORIZONTAL HAIRPINS

TOP BARS ld (a) (ACI

12.2.3) CA

PAC

ITY

SE

E N

OTE

(4)

(in.) (kips)

FACTORS FOR DIFFERENT




TABLE 4: Pretension Load and Torque Recommendations*

1/2 13 30 3,7805/8 11 60 6,0603/4 10 100 9,0607/8 9 160 12,570

1 8 245 16,5301-1/8 8 355 21,8401-1/4 8 500 27,8701-1/2 8 800 42,1501-3/4 8 1,500 59,400 2 8 2,200 79,5602-1/4 8 3,180 102,6902-1/2 8 4,400 128,7602-3/4 8 5,920 157,770 3 8 7,720 189,720

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.

* From PIP REIE686, Recommended Practices for Machinery Installation and Installation Design, Appendix A.

Note 3: Based upon 30-ksi internal bolt stress

Nominal Bolt Diameter (inches)

Number of Threads (per inch)

Torque (foot-pounds)

Pretension Load (pounds)




FIGURE A: Anchor Details

P1

NOTE: DISTANCE BETWEEN BOTTOM OF SLEEVE AND ANCHOR BEARING

TYPE 2

SURFACE, h ' , SHALL NOT BE LESS THAN 6d NOR 6-IN.

TACK

NUTWELD

DIST.

PR

OJ E

CTI

ON

o

TYPE 1

s

T.O. CONC.

T.O. CONC.

a

ef

PRO

J EC

TIO

N

DIST.EDGE

P s

e

EDGE

h

h

C

h h

'd

d

C

h a

ef

h d s

d o

h P

sh

' e

o

REFER TO TABLE 1 FOR MINIMUM DIMENSIONS

e




Octagon "Weak Anchors"

Do =

Pythagorean theorem: Failure planes overlap each other to go clear across pedestal.c2

2 + (AC/2)2 = (Do/2)2 Av = 1.5c1D (Max. Av = nAvo = n4.5c1

2)

n = Total number of bolts = 12

Calculate Do so that equivalent circle has same area as octagon.

For input into PIP STE05121 Anchor Bolt Design Spreadsheet, available to PIP Members only.

Av = 1.5c1Dc2, c4 = [(1.03D/2)

2-(AC/2)2]1/2

= 1.03D

Note: Area of octagon = 0.828D2

Do2 = 0.828D2(4)

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

0.828D2(4)

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

Approximate solution

Av (max) = n 4.5c12

c1= Do /2 - AC/2

Do2/4 = 0.828D2c1 =1.03D/2 - AC/2




shall be used for resisting shear.

n = 6

c1 (ALT) =As shown abovec2 (ALT) = (D-Cos(45

)AC)/2Av = 1.5c1(ALT) DAv (max) = n 4.5(c1(ALT))

2

n = 4

Av = 1.5c1 DAv (max) = n 4.5c1

2

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 c1 for the chosen bolt

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.

c1 =As shown abovec2 = (D-AC)/2

For input into PIP STE05121 Anchor Bolt Design Spreadsheet , available to PIP Members only. Alternate




FIGURE C-1: Tensile Reinforcement - Vertical Dowels

NOTE: Refer to Section 7.3

SECTION

(h /3 max.)

a

ef

T.O. CONC.

1.5 s

h

X

o1

b

(min

.)

TO MATDOWEL

(min

.)

dC

X PLAN

(Centerline of Anchor Bolt to Centerline of Dowel = (W /2 + X + (d /2)) e

f

VERTICAL DOWELSEDGEDIST.

(h

/3 M

ax.)

c or c1 2

h rb

d

h

h l

dl

d

d

W

ef

Required Anchor Embedment, h = l + C + (X + d /2) /1.5bd

Refer to Table 3 for ld

ef




FIGURE C-2: Tensile Reinforcement - Vertical Hairpin

SECTION

REINFORCEMENTHAIRPIN

(h /3 max.)

T.O. CONC.

ef

(h /3 max.)

h

X

o


PLAN

X

(min

.)

dh

(min

.)

d

1.51

ef

h

d

W

l l

ef

Refer to Table 3 for l and l .d dh




FIGURE D-1: Shear Reinforcement - Horizontal Hairpin

HAIRPIN

SECTION

REINFORCEMENT

EDGE DISTANCE

EDGE DISTANCE

SHEAR DIRECTION

CONCRETEFACE OF

5 d (min.)

ANCHOR


PLAN

ANCHOR

MIN

IMU

M

CO

VE

R

d

HO

OK

DIM

EN

SIO

N1 8

0 D

EG

. STD

.

l

dl

5 d (min.)

Refer to Table 3 for l .d

o

o




FIGURE D-2: Shear Reinforcement - Closed Ties

PLAN

SHEAR DIRECTION

SECTION

REINFORCEMENTCLOSED TIE

PLAN

EDGE DISTANCEANCHOR

EDGE DISTANCE

FACE OF CONCRETE

EDGE DISTANCE

FACE OF CONCRETE

5 d (min.)

ANCHORWEAK

STD

. HO

OK

D

IME

NS

ION

180

DE

G.

ANCHORWEAK

180

DE

G.

DIM

EN

SIO

NS

TD. H

OO

K

ANCHOR

MIN

IMU

M

REINFORCEMENTCLOSED TIE ANCHOR

STRONG


STRONGANCHOR

o

5 d (min.)o

5 d (min.)o




FIGURE D-3: Shear Reinforcement - Anchored Reinforcement

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.

PLATE

ANCHORED REINFORCEMENT

LINE AT SURFACE OFHALF-PYRAMID INTERSECTING

z = vertical hairpin concrete cover + 0.5d d

CO

NC

RE T

E

HALF-PYRAMID INTERSECTING HAIRPINLINE AT SURFACE OF

FAILURE HALF-PYRAMID

REINFORCEMENTANCHORED

PLAN

FAC

E O

F

LINE AT SURFACE OFHALF-PYRAMID INTERSECTINGHAIRPIN

SECTIONANCHOREDGE

DIST.

HAIRPIN

SECTION

REINFORCEMENTANCHORED

Z Z

SHEAR DIRECTION

ANCHOR

ANCHOR

d

SHEAR DIRECTION

ANCHOR ANGLE

d

ANCHOR

11.5

l

l

dl

dl l = development length of reinforcementb

ANCHORED REINFORCEMENT(ALTERNATE)

11.5

1.51




FIGURE D-4: Shear Reinforcement - Shear Angles

FAILUREHALF-TRUNCATEDPYRAMID

ANCHOR

SHEAR DIRECTION

SECTIONNOTE: DEDUCT AREA OF THE BEARING SURFACE OF

OF THE FAILURE HALF-TRUNCATED PYRAMID).SHEAR ANGLE IN CALCULATING A (THE PROJECTION

HALF-TRUNCATEDFAILURE

PYRAMID

EDGE DISTANCE

CONCRETEFACE OF

1

PLAN

1

TACK WELD

ANCHOREDGE DISTANCE5d (min.)o

p

5d (min.)o




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

ANCHORBOLT

C AND C ARE COMPRESSION1 2FORCES.1 2 3

FORCES.ACTUAL FORCES WILL VARYWITH GEOMETRY.

VERTICALREBAR

T1

T1

1C

C1

TIE

T2

T3

25M I N.

25M I N.

T , T , AND T ARE TENSION

NOTES:

1.

2.

3.




FIGURE E: Minimum Lateral Reinforcement - Pedestal

PROVIDE THIS ADDITIONAL

OR IF SHEAR LUG IS USEDTIE IN HIGH-SEISMIC AREAS

2" (O

R L

ESS)

4 "1

1/2"




FIGURE F: Coefficients of Friction

= 0.90

= 0.70

= 0.55

CONCRETE

GROUT

SURFACE

CONCRETE SURFACE

GROUT

GROUT

CONCRETE SURFACE




Notes:1. Materials:

Anchor plate: ASTM A36Anchor rod: ASTM A36 or F1554 GR 36.Nuts: ASTM A563 Grade A heavy hexWasher: ASTM F436Pipe sleeve: ASTM A53 SCH 40

2. Weld shall be inaccordance with AWS D1.1 .3. Fabrication Sequence:

A.

B.

C. Hold nut 2, tighten nut 3 to a snug tight condition.D. Position and weld the pipe sleeve.

ANCHOR ROD

NOMINAL PIPE SLEEVE

ANCHOR PLATETHICKNESS (T)

(in.) (in.) (in.)

3/4 1-1/2 5/8

7/8 2 7/8

1 2 7/8

1-1/8 2-1/2 1

1-1/4 2-1/2 1

1-1/2 3 1 1/4

1-3/4 3-1/2 1 1/2

2 4 1 3/4

2-1/4 5 2

2-1/2 5 2 1/4

2-3/4 5 2 1/4

3 6 2 1/2

FIGURE G: Pretensioned Anchors for Turbines and Reciprocating Compressors

Position anchor rod to obtain the specified projection above the anchor plate.

ANCHOR PLATE DIMENSIONS

(in.)

Holding nut 1, tighten nut 2 to a snug tight condition.

2 1/2 x 2 1/2

3 x 3

3 x 3

3 1/2 x 3 1/2

3 1/2 x 3 1/2

4 1/2 x 4 1/2

5 x 5

5 1/2 x 5 1/2

6 1/2 x 6 1/2

7 x 7

7 x 7

8 x 8

1/2WASHER

DUCT TAPE

PIPE SLEEVE

ANCHOR ROD

PLATEANCHOR

FILL WITH ELASTOMERICMOLDABLE NON-HARDENING

NUT 3NUT 2

NUT 1

T 4d +

T

FDN.

1

GROUT TOP NUT

DIMENSIONS ARE IN INCHES

T0P OF DUCT TAPEBOTTOM OF GROUT

BOTTOM OF DUCT TAPE

doMATERIAL

o




FIGURE H: Anchor-Tightening Sequence

1

EQUIPMENT

SEQUENCETIGHTENING

10

6

8

4

12

EQUIPMENT

211

5

7

9

3




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 (Vu) = 17 kips Moment (Mu) = 146 kip-feet Tension (Nu) = 17 kips Low-seismic area (ductility not required) f'c = 3000 psi, A36 anchor material

MP = 0 T = (146 k-ft x 12 + 17 k x 8.625")/(11 + 8 - 2.67) T = 116 k for 2 bolts P = 116 - 17 = 99 kips

Resisting friction load (Vf) = m 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.

Nom. Anchor Diameter = 1 3/4" Anchor Embedment = 21" (12 anchor diameters) Pedestal Size = 6' 4" x 5' 2" (c1 = 30", c2 = 28", c3 = 46", c4 = 28", s2 = 6", s1 = 0") (Because only two bolts resist tension, s1 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.

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.)

TOP OF PED.

ANCHOR BOLT

N M

8" 11"

x

P

T

V

uu

u



Anchor Bolt Design SpreadsheetInput

PIP STE05121

Company

Project Project #

Subject

Name Date 11/7/2002 Sheet Number 1Checked by Check Date 11/7/2002 Total Sheets 1

LOADING CONDITIONS DESIGN CONSIDERATIONSNote: Calculations are per ACI 318-02 Appendix D. Ductility required? Tension Shear

Nu and Vu were factored using factors from ACI 318-02? Intermediate or high seismic risk?

Factored tensile load (kips) = Nu = 116 Specified concrete strength (psi) = f'c = 3000Factored shear load (kips) = Vu = 0Is there a built-up grout pad?

ANCHOR DATA, EMBEDMENT, AND THICKNESS OF MEMBERAnchor material type = Adequate supplementary reinf. provided to resist tension loads in anchors?

Nominal anchor diameter (in.) = Adequate reinforcement provided to resist shear loads in anchors?21.00 = hef ECCENTRICITY60.00 = h Eccentricity of tensile force on group of tensile anchors (in.)

Number of anchors in tension = n(tension) = 2 eN' = 0 (0=single anchor)Number of anchors in shear = n(shear) = 4 Eccentricity of shear force on group of anchors (in.)

CONCRETE FAILURE AREAS (Note ev' must be less than s perpendicular to shear) eV'= 0Do you want to manually input the value of An? no EDGE DISTANCES AND SPACING

An = 200An= 3813

Do you want to manually input the value of Av? no c1 = 30.0 c3 = 46.0 s1 = 0.0 c1 = 30.0 s2 = 6.0Av = 2000 c2 = 28.0 c4 = 28.0 s2 = 6.0 c2 = 28.0

Av= 2790 c4 = 28.0c1 = edge distance in direction of Vn (perp.) c2 = least edge distance perpendicular to c1

Breakout cone for tension Breakout cone for shearSUMMARY OF RESULTS

Nn =Vn =

Nu/(Nn) + Vu/(Vn) = 0.00 = 0.99 = Nu = >= Vu =

116.0 kips

No

No

Yes

F1554 Gr 36

1 3/4

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

No

hef

1.5hef 1.5hef

35o

NU

No

No

c1

c

2

s

2

c

4

VU

c

2

s

2

c3s1c1c

4

No

No

h

o

r

1

.

5

c

1

c4

c1c2

VU

s2

Section 9.2

perpendicular to edge

c1

1

.

5

c

1 35o

VU (perpendicular)

1

.

5

c

1 VU (parallel)

Process Ind u stry Practices A-20

January 2003Output

PIP STE05121Anchor Bolt Design Spreadsheet

Company Sheet 1 of 1Project Project #

Subject

Name Date

Checked by Check Date

BOLT PARAMETERSGrade fy 36 ksi hef 21.00 in.Size 1 3/4 in. fut 58 ksi n(tension) 2do 1.750 in. Ase 1.900 sq. in. n(shear) 4

Ab 4.144 sq. in.

LOAD CONDITIONS REINFORCEMENTLOAD FACTORS Section 9.2 ADEQUATE REINF NOT PROVIDED TO RESIST TENSIONTENSILE LOAD, Nu 116.0 kips ADEQUATE REINF NOT PROVIDED TO RESIST SHEARSHEAR LOAD, Vu 0.0 kips

DESIGN CONSIDERATIONSDUCTILITY NOT REQD IN TENSION CONCRETE STRENGTH, f'c 3000 psiDUCTILITY NOT REQD FOR SHEAR CRACKING MOD FACTOR, 7 1.4LOW SEISMIC RISKECCENTRICITIES eN' = 0.00 in. eV' = 0.00 in.

DESIGN FOR TENSION DESIGN FOR SHEARSTEEL STRENGTH Ns 220.4 kips Vs 211.6 kips

CONCRETE BREAKOUT STRENGTH OF ANCHOR(S) Ncb or Ncbg 167.6 kips Vcb or Vcbg 108.0 kips

PULLOUT STRENGTH OF ANCHOR(S) nNpn 278.5 kips Vcp 335.1 kips

CONCRETE SIDE-FACE BLOWOUT STRENGTH OF HEADED ANCHOR(S)

Nsb or Nsbg (governing) NA

SUMMARY OF RESULTSFAILURE AREAS TENSION

Steel Capacity 165.3 kips TENSION SHEAR Concrete Capacity 117.3 kips

c1 30.00 in. 30.00 in.c2 28.00 in. 28.00 in. SHEARc3 46.00 in. Steel Capacity 137.5 kipsc4 28.00 in. 28.00 in. Concrete Capacity 75.6 kipss1 0.00 in.s2 6.00 in. 6.00 in. INTERACTION OF TENSILE AND SHEAR FORCES

An or Av 3813.0 sq. in. 2790.0 sq. in. 117.3 kips = Nn* >= Nu = 116.0 kipsCalculated Calculated 75.6 kips = Vn* >= Vu = 0.0 kips

Nu/(Nn*) + Vu/(Vn*) = 0.99 + 0.00


Calculations PIP STE05121Anchor Bolt Design Spreadsheet

Selected Bolt: 1 3/4 in. F1554 Gr 36 No. of Boltsdo = 1.750 in. Ase = 1.900 sq. in. fy = 36 ksi nt(tension) = 2hef = 21.0 in. Abrg = 4.144 sq. in. fut = 58 ksi nv(shear) = 4

Note: Figures in parenthesis and in red refer to equations or paragraphs in ACI 318-02 , Appendix D.

Steel Strength in Tension: Ns = nAsefut (fut < 1.9fy and fut < 125 ksi) = 220.4 kips (D-3)

1. Concrete breakout strength of anchor in tension:AN(calc) = 3813.0 sq. in. Use AN = 3813.0 sq. in. ANo = 9hef

2 = 3600.0 sq. in. (D-6)hef(max) = 20.0 in. Use hef = 20.0 in. (D.5.2.3)

Y1 = [1/(1 + 2eN'/3hef)


Calculations PIP STE05121Anchor Bolt Design Spreadsheet

Vb = 7(l/do)0.2(do)

0.5(f'c)0.5(c1)

1.5 = 126.3 kips (D-23)Y5 = 1/(1 + 2eV'/3c1) = 1.5c1] = 0.887 (D-26 [Errata] or D-27)Y7 = 1.4 (D.6.2.7)

Vcb or Vcbg = (AV/AVo)Y5Y6Y7Vb = 108.0 kips (D-20 or D-21) Shear perpendicular to edge



EXAMPLE 2 - Column Plate Connection - Supplementary Tensile Reinforcing

Same data as Example 1. Use supplementary tensile reinforcing to reduce pedestal size.

Shear (Vu) = 17 kips Per Example 1:Moment (Mu) = 146 kip-feet T = 116 k on two boltsTension (Nu) = 17 kips Friction will take shear load.

Nom. anchor diameter = 1-3/4"

Assume a 2'-0" x 2'-6" pedestal.

Assume anchors are resisted by three hairpins. 116k / 3 = 38.7 kips Per Table 3 of PIP STE05122, one #8 hairpin resists 48.37 kips. OK. ldh (min) = 15.3" per Table 3. Width of hairpin = 6.0" + #8 diam. = 7.0". See Table 3.

Space hairpins 3" away from each anchor. Distance from anchor to leg of hairpin = [32 +(7.0/2)2]0.5 = 4.61" Required hef = C + ldh + 4.61/1.5. See Figure C-2. Where C = concrete cover = 2" hef = 2 + 15.3 + 4.61/1.5 = 20.4"

min. hef = 12 d0 = 12 x 1.75 = 21"Final Design Use hef = 21"

ELEVATION

#8 HAIRPIN

1 3/4" DIA. ANCHOR

ef (TYP.)HAIRPIN

PLAN

dh

d

1.51

h

= 21

"

l o

r l

*

(TYP.)

C =

2"

CLE

AR (TYP.)

1'-4"

2'-6"

3"3"

6"6"

2'-0

"ANCHOR(TYP.)

* USE l IF HOOK IS ADDEDAT BOTTOM OF HAIRPIN

dh (NOTE: OTHER REINF. NOTSHOWN FOR CLARITY)

T

(TYP.)




Example 3 - Shear Lug Plate Section Design

V = 40 (ULTIMATE)

PLAN

SECTION

uK




EXAMPLE 3 - Shear Lug Plate Section Design Design a shear lug plate for a 14-in. square base plate, subject to a factored axial dead load of 22.5 kips, factored live load of 65 kips, and a factored shear load of 40 kips. The base plate and shear lug have Fy = 36 ksi and f'c = 3 ksi. The contact plane between the grout and base plate is assumed to be 1 in. above the concrete. A 2-ft 0-in. square pedestal is assumed. Ductility is not required.

Vapp = Vu Vf = 40 (0.55)(22.5) = 27.6 kips

Bearing area = Areq = Vapp / (0.85 fc) = 27.6 kips / (0.85*0.65*3 ksi) = 16.67 in.2

On the basis of base plate size, assume the plate width, W, will be 12 in.

Height of plate = H = Areq / W + G = 16.67 in.2 /12 in. + 1 in. = 2.39 in. Use 3 in.

Ultimate moment = Mu = (Vapp / W) * (G + (H G)/2) = (27.6 kips / 12 in.) * (1 in. + (3 in.-1 in.)/2) = 4.61 k-in. / in.

Thickness = t = [(4 * Mu)/(* Fy)] = ((4*4.61 kip-in.)/(0.9*36 ksi)) = 0.754 in. Use 0.75 in.

This 12-in. x 3-in. x 0.75-in. plate will be sufficient to carry the applied shear load and resulting moment. Design of the weld between the plate section and the base plate is left to the engineer.

Check concrete breakout strength of the shear lug in shear.

Distance from shear lug to edge of concrete = (24 - 0.75) / 2 = 11.63 in.

AV = 24 * (2+11.63) (12 * 2) = 303 in.2

Vcb = AV*4**[fc]0.5 = 303 * 4 * 0.85 * [3000]0.5 = 56400 lb = 56.4 kips > 27.3 kips OK




Example 4 - Shear Lug Pipe Section Design

V = 40 (ULTIMATE)

PLAN

SECTION

uK




D = 8.625 in., t = 0.322 in., S = 16.81 in.3, Z = 22.2 in.3

= 27.63 kips * (1 in. + (3.5 in. - 1 in.)/2) = 62.17 k-in.

Mn = S [600/(D/t) + Fy] = 16.81 in.3 *(600/(8.625 in./0.322 in.) + 36 ksi) = 982 k-in.

or Mn = Z * Fy = 22.2 in.3 * 36 ksi = 799 k-in Use Mn = 799 k-in

b = 0.9bMn = (0.9)*(799 k-in.) = 719 k-in. > 62.17 k-in. OK

Check Vn = 0.6 Fy (D2 (D-2t)2)/4 = 0.6* 36 ksi * * ( 8.6252 (8.625 2*0.322)2 ) in.2 / 4

= 181.4 kipsv = 0.9

vVn = (0.9)*(181.4 kips) = 163.2 kips > 27.6 kips OK

Av = 24*(2.5 + 7.69) 8.62*2.5 = 223 in.2

Vcb = Av*4*f*[fc]0.5 = 223 * 4 * 0.85 * [3000]0.5 = 41500 lb = 41.5 kips > 27.3 kips OK

Vapp = Vu Vf = 40 (0.55)(22.5) = 27.6 kips

Design a shear lug pipe section for a 14-in. square base plate, subject to a factored axial dead load of 22.5 kips, factored live load of 65 kips, and a factored shear load of 40 kips. The base plate and shear lug have Fy = 36 ksi and f'c = 3 ksi. The contact plane between the grout and base plate is assumed to be 1 in. above the concrete. A 2-ft 0-in. square pedestal is assumed. Ductility is not required.

EXAMPLE 4 - Shear Lug Pipe Section Design

Ultimate moment = Mu = Vapp * (G + (H G)/2)

Height of pipe = H = Areq / D + G = 16.67 in.2 / 8.625 in. + 1 in. = 2.93 in. Use 3.5 in.

Based on base plate size, assume the pipe diameter will be 8-in. nominal std. weight pipe.

Bearing area = Areq = Vapp / (0.85 fc) = 27.6 kips / (0.85*0.65*3 ksi) = 16.7 in.2

Distance from edge of pipe to edge of concrete = (24 8.625) / 2 = 7.69 in.Check failure plane of pedestal:

This 3.5-in.-long x 8-in.-diameter nominal std. weight pipe will be sufficient to carry the applied shear load and resulting moment.

Check moment:


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STE05121 - Anchor Bolt Design Guide