ACI 349.2R-97
Embedment Design Examples Reported Reported by by ACI ACI Committee Commi ttee 349
Charles A. Zalesiak Chairman
Hans G. Ashar
Gunnar A. Harstead
Richard S. Orr*
Ranjit Bandyopadhyay Bandyopadhyay *
Christopher Christopher Heinz
Robert B. Pan
Ronald A. Cook*
Charles J. Hookham
Julius V. Rotz †
Jack M. Daly
Richard E. Klingner
Robert W. Talmadge
Arobindo Dutt
Timothy J. Lynch
Chen P. Tan
Branko Galunic
Frederick L. Moreadith
Richard E. Toland
Dwaine A. Godfrey
Dragos A. Nuta
Donald T. Ward
Herman L. Graves III
Albert Y. C. Wong
* Major contributor to the report † Deceased
Appendix B of ACI 349 was developed to better define the design require-
PART A—Examples: Ductile single embedded element in semi-in nite concrete. . . .p. 349.2R-3 Example A1 Single stud, tension only Example A2 Single stud, shear only Example A3 Single stud, combined tension and shear Example A4 Anchor bolt, combined tension and shear Example A5 Single rebar, combined tension and shear
ments for steel embedmnts revisions are periodically made to the code as a result of on-going research and testing. As with other concretebuilding codes, the design of embedments embedments attempts to assure a ductile failure mode so that the reinforcement yields before the concrete fails. In embedments designed for direct loading, the concrete pullout strength must be greater than the tensile strength of the steel. This report presents a series of design examples of ductile steel embedments. These examples have been updated to include the revision incorparated in Appendix B of ACI 349-97. Keywords : Anchorage (structural); anchor bolts; anchors (fasteners);
embedment; inserts; loads (forces); load transfer; moments; reinforced concrete; reinforcing steels; shear strength; structural design; studs; tension.
CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . .p. 349.2R-2 Notation. . . . . . . . . . . . . . . . . . . . . . . . . . p. 349.2R-2
ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in planning, designing, executing, and inspecti inspecting ng construc construction tion.. This doc ument is intended for th e use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. conta ins. The American Concrete Concrete Institute Institute disclaims disclaims any and all all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not be made in contract documents. If items found in this document are desired by the ArchiArchitect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/ Engineer.
PART B—Examples: Ductile multiple embedded elements in semi-in nite concrete. .p. 349.2R-10 Example B1 Four-stud rigid embedded plate, tension only Example Example B2(a) Four-stud Four-stud rigid rigid embedded embedded plate, plate, combined shear and uniaxial moment Example Example B2(b) Four-stud Four-stud flexible flexible embedded embedded plate, combined shear and uniaxial moment Example Example B2(c) Four-bolt Four-bolt rigid surface-m surface-mounte ounted d plate, combined shear and uniaxial moment Example Example B3(a) Four-stud Four-stud rigid rigid embedded embedded plate, plate, combined tension, shear, and uniaxial moment Example Example B3(b) Four-stud Four-stud flexible flexible embedded embedded plate, combined tension, shear, and uniaxial moment Example B4 Four-stud rigid embedded plate in thin slab, tension only APPENDIX A—Projected area (Acp) for four studs stud s. . . . . . . . . . . . . . . . . . .p. 349.2R-26 ACI 349.2R-97 became effective October 16, 1997. Copyright © 1997, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical device, printed, written, or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.
349.2R-1
349.2R-2
MANUAL OF CONCRETE PRACTICE
INTRODUCTION This report has been prepared by members of the ACI 349 Sub-Committee on Steel Embedments to provide examples of the application of the ACI 349 Code to the design of steel embedments. The ACI 349 Committee was charged in 1973 with preparation of the code covering concrete structures in nuclear power plants. At that time, it was recognized that design requirements for steel embedments were not well defined and a special working group was established to develop code requirements. After much discussion and many drafts, Appendix B was approved and issued in the 1978 Supplement of ACI 349 covering the design of steel embedments. Subsequently, the Sub-Committee has continued to monitor on-going research and testing and to incorporate experience of applying the Code. Periodic revisions have been made to the Code and Appendix B. The underlying philosophy in the design of embedments is to attempt to assure a ductile failure mode. This is similar to the philosophy of the rest of the concrete building codes wherein, for example, flexural steel for a beam is limited to assure that the reinforcement steel yields before the concrete crushes. In the design of an embedment for direct loading, the philosophy leads to the requirement that the concrete pull-out strength must be greater than the tensile strength of the steel. This report includes a series of design examples starting with simple cases and extending to more complex cases for ductile embedments. The format for each example follows the format of the Strength Design Handbook, SP-17, and provides a reference back to the code paragraph for each calculation procedure.
NOTATION a = Acp =
Ac = Ah = As = Ast = Asv =
depth depth of equiv equivale alent nt stress stress block, block, in. effec effecti tive ve stres stresss area area defined defined by by the proj project ected ed area area of the 45 degree stress cone radiating towards the attachment from the bearing edge of the anchor, sq. sq. in. in. effec effecti tive ve stress stress area area of of ancho anchor, r, sq. in. area area of anch anchor or head head,, sq. sq. in. in. area area of stee steel, l, sq. in. in. area area of stee steell requir required ed to resist resist tensio tension, n, sq. sq. in. area area of stee steell requir required ed to resist resist shear shear,, sq. in. in.
A r =
A vf = b =
B c C d b d h d s F y ′ f ′ f c f ut f y h k t r
= = = = = = = = = = = = ld = L d =
M n = M u = M y = n = P d = P n = P u = R = S = t = T = T h = V n = V u = α = β = γ = µ = φ =
reduct reduction ion in in effec effecti tive ve stre stress ss area area to acco account unt for for limited depth of concrete beyond the bearing surface of the embedment, sq. in. area area of shear shear fric frictio tion n reinf reinforc orceme ement, nt, sq. in. width width of of embed embedded ded or surf surface ace mounte mounted d plate plate,, or width of an anchor group, measured out to out of bearing edges of the outermost anchor heads, in. overl overlapp apping ing stre stress ss cone cone fact factor or (see (see Appen Appendix dix A) spac spacin ing g or cove coverr dime dimens nsio ion, n, in. in. comp compre ress ssiive reac reacti tion on nomina nominall diam diamete eterr of reinfo reinforci rcing ng bar bar,, in. in. diamet diameter er of anchor anchor head head or or reinf reinforc orcing ing bar bar,, in. diamet diameter er of of tens tensile ile stress stress compon component ent,, in. in. specifi specified ed yiel yield d stre strengt ngth h of steel steel plat plate, e, psi psi specifi specified ed compr compress essiv ivee streng strength th of conc concret rete, e, psi specifi specified ed tensil tensilee stre strengt ngth h of steel, steel, psi specifi specified ed yield yield streng strength th of steel, steel, psi overa overall ll thic thickne kness ss of of concr concrete ete member member,, in. in. tran transv sver erse se rei reinf nfor orce ceme ment nt ind index ex deve develo lopm pmen entt len lengt gth, h, in. in. embedm embedment ent depth depth of of ancho anchorr head head meas measure ured d from from attachment of anchor head to tensile stress component, to the concrete surface, in. nomi nomina nall mom momen entt str stren engt gth h fact factor ored ed mom momen entt load load on on embe embedm dmen entt elasti elasticc mome moment nt capaci capacity ty of steel steel plate plate numb number er of thre thread adss per per inch inch design design pullou pulloutt stren strength gth of of concre concrete te in in tensi tension on nomi nomina nall axi axial al stre streng ngth th facto factored red exte externa rnall axial axial load load on the the ancho anchorag ragee radius radius of 45 45 degre degreee stre stress ss cone cone,, in. in. (see (see A cp ) spac spacin ing g bet betwe ween en anch anchor ors, s, in. in. thic thickn knes esss of of pla plate te,, in. in. tension force thic thickn knes esss of of anc ancho horr hea head, d, in. in. nomi nomina nall she shear ar stre streng ngth th fact factor ored ed she shear ar loa load d on emb embed edme ment ntss rein reinfo forc rcem emen entt loca locati tion on fac facto torr coating factor rein reinfo forc rcem emen entt size size fact factor or coef coeffic ficie ient nt of fric fricti tion on stre streng ngth th red reduc ucti tion on fac facto torr
