349.2R-97 Embedment Design Examples - Free

1 ACI became effective October 16, 2002, American Concrete rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic ormechanical device, printed, written, or oral, or recording for sound or visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission inwriting is obtained from the copyright Committee Reports, Guides, Standard Practices, and Commen-taries are intended for guidance in planning, designing, executing,and inspecting document is intended for theuse of individuals who are competent to evaluate the signifi-cance and limitations of its content and recommendations andwho will accept responsibility for the application of the materialit contains.

2 TheAmerican Concrete Institute disclaims any and allresponsibility for the stated principles. The Institute shall not be lia-ble for any loss or damage arising to this document shall not be made in contract docu-ments. If items found in this document are desired by the Archi-tect/Engineer to be a part of the contract documents, they shall berestated in mandatory language for incorporation by the B of ACI 349 was developed to better define the Design require-ments for steel embedmnts revisions are periodically made to the code as aresult of on-going research and testing. As with other concretebuildingcodes, the Design of embedments attempts to assure a ductile failure mode sothat the reinforcement yields before the concrete fails.

3 In embedmentsdesigned for direct loading, the concrete pullout strength must be greaterthan the tensile strength of the steel. This report presents a series of designexamples of ductile steel embedments. These Examples have been updated toinclude the revision incorparated in Appendix B of ACI : Anchorage (structural); anchor bolts; anchors (fasteners); Embedment ; inserts; loads (forces); load transfer; moments; reinforced con-crete; reinforcing steels; shear strength; structural Design ; studs; ..p..p. A Examples : Ductile single embeddedelement in semi-in nite concrete..p. A1 Single stud, tension onlyExample A2 Single stud, shear onlyExample A3 Single stud, combined tension and shearExample A4 Anchor bolt, combined tension and shearExample A5 Single rebar, combined tension and shearPART B Examples : Ductile multiple embeddedelements in semi-in nite concrete.

4 P. B1 Four-stud rigid embedded plate, tension onlyExample B2(a)Four-stud rigid embedded plate,combined shear and uniaxial momentExample B2(b)Four-stud flexible embedded plate,combined shear and uniaxial momentExample B2(c)Four-bolt rigid surface-mounted plate,combined shear and uniaxial momentExample B3(a)Four-stud rigid embedded plate,combined tension , shear, anduniaxial momentExample B3(b)Four-stud flexible embedded plate,combined tension , shear, anduniaxial momentExample B4 Four-stud rigid embedded plate in thin slab, tension onlyAPPENDIX A Projected area (Acp) for four studs ..p. Design ExamplesReported by ACI Committee 349 ACI A. ZalesiakChairmanHans G. Ashar Gunnar A. Harstead Richard S.

5 Orr*Ranjit Bandyopadhyay* Christopher Heinz Robert B. PanRonald A. Cook* Charles J. Hookham Julius V. Rotz Jack M. Daly Richard E. Klingner Robert W. TalmadgeArobindo Dutt Timothy J. Lynch Chen P. TanBranko Galunic Frederick L. Moreadith Richard E. TolandDwaine A. Godfrey Dragos A. Nuta Donald T. WardHerman L. Graves III Albert Y. C. Wong* Major contributor to the report OF CONCRETE PRACTICEINTRODUCTIONThis report has been prepared by members of the ACI 349 Sub-Committee on Steel Embedments to provide examplesof the application of the ACI 349 Code to the Design of steelembedments.

6 The ACI 349 Committee was charged in 1973with preparation of the code covering concrete structures innuclear power plants. At that time, it was recognized that de-sign requirements for steel embedments were not well de-fined and a special working group was established todevelop code requirements. After much discussion and manydrafts, Appendix B was approved and issued in the 1978 Supplement of ACI 349 covering the Design of steel embed-ments. Subsequently, the Sub-Committee has continued tomonitor on-going research and testing and to incorporate ex-perience of applying the Code. Periodic revisions have beenmade to the Code and Appendix underlying philosophy in the Design of embedments isto attempt to assure a ductile failure mode.

7 This is similar tothe philosophy of the rest of the concrete building codeswherein, for example , flexural steel for a beam is limited toassure that the reinforcement steel yields before the concretecrushes. In the Design of an Embedment for direct loading,the philosophy leads to the requirement that the concretepull-out strength must be greater than the tensile strength ofthe report includes a series of Design Examples startingwith simple cases and extending to more complex cases forductile embedments. The format for each example followsthe format of the Strength Design Handbook, SP-17, andprovides a reference back to the code paragraph for each cal-culation of equivalent stress block, stress area defined by the projected areaof the 45 degree stress cone radiating towards theattachment from the bearing edge of the anchor,sq.

8 Stress area of anchor, sq. of anchor head, sq. of steel, sq. of steel required to resist tension , sq. of steel required to resist shear, sq. in effective stress area to account forlimited depth of concrete beyond the bearingsurface of the Embedment , sq. of shear friction reinforcement, sq. of embedded or surface mounted plate, orwidth of an anchor group, measured out to out ofbearing edges of the outermost anchor heads, stress cone factor (see Appendix A)c=spacing or cover dimension, reactiondb=nominal diameter of reinforcing bar, of anchor head or reinforcing bar, of tensile stress component, yield strength of steel plate, psif c=specified compressive strength of concrete, psifut=specified tensile strength of steel, psify=specified yield strength of steel, psih=overall thickness of concrete member, reinforcement indexld=development length, depth of anchor head measured fromattachment of anchor head to tensile stresscomponent, to the concrete surface.

9 Moment strengthMu=factored moment load on embedmentMy=elastic moment capacity of steel platen=number of threads per inchPd= Design pullout strength of concrete in tensionPn=nominal axial strengthPu=factored external axial load on the anchorageR=radius of 45 degree stress cone, in. (seeAcp)S=spacing between anchors, of plate, forceTh=thickness of anchor head, shear strengthVu=factored shear load on embedments =reinforcement location factor =coating factor =reinforcement size factor = coefficient of friction =strength reduction Design EXAMPLESPA RT AEXAMPLES:Ductile single embedded elementin semi-infinite concreteExample A1 Single stud, tension onlyExample A2 Single stud, shear onlyExample A3 Single stud, combined tension and shearExample A4 Anchor bolt, combined tension and shearExample A5 Single rebar, combined tension and OF CONCRETE PRACTICED esign an Embedment using a stud welded to an embedded.

10 =4000 psify=50,000 psifut=60,000 psiPu=8 kipswherePu is the required factored external loadas defined in Section of the cExample A1 Single stud, tension onlyCODESECTIONDESIGN PROCEDURECALCULATIONSTEP 1: Determine required steel area of the studAssume that the load is applied directly over thestud and that a plate size of 3 in. 3 in. 3/8 been established by requirements of the external (required strength) andinternal ( Design strength) forces and solve for therequired steel area for the = Pn = AsfyAs = 8/ [( )(50)] = one1/2 in. diameter stud,As = > 2: Check anchor head (a) ) Area of the anchor head (Ah) (including thearea of the tensile stress component) is atleast times the area of the tensile = (dh/2)2 = (per manufacturer s data,dh = 1 in.