aci 318 technical changes

aci 318 technical changes In this third installment of our coverage on the significant changes in ACI 318-14, the technical changes in the upcoming new edition of the concrete code are presented. The first two installments – a cross-reference table showing how the 2014 edition of the code has been reorganized compared to its 2011 edition, and the nontechnical changes made to the 2014 edition of the code can be found here and here.

Public Discussion Period of Proposed Revisions: From ACI 318-02 to ACI 318-05 Several important improvements and clarifications have been made since the 2002 edition of ACI 318, “Building Code Requirements for Structural Concrete and Commentary.” For the sake of clarity, the revisions to ACI 318-02 were split into a list of technical changes and a list of notation changes The technical changes are given in this issue of Concrete International and on the ACI website Provisions that include both technical and notational changes are shown with the technical changes The revised list of notation is incorporated into Chapter and is included with the technical changes Additional notation changes that are considered strictly editorial are available on the ACI website (www.concrete.org, click on “Publications” on the menu bar, then on “Standardization Actions.”) NOTATION • To make the code easier to use, ACI Committee 318 decided to unify the notation Four main goals were achieved: 1) Provided a unique definition for each notation; 2) Consolidated similar notations as appropriate and eliminated unnecessary ones; 3) Moved the list of notation from Appendix E to Chapter 2; and 4) Removed notation list from beginning of each chapter TECHNICAL • Changed “welded wire fabric” to “welded wire reinforcement” to be consistent with current practice; • Updated the referenced standards; • Clarified the use of fiber reinforced polymer (FRP) reinforcement; • Made construction joint location for post-tensioned slabs distinct from that for reinforced concrete slabs; • Clarified computation of the design flexural strength of pretensioned members at sections within transfer and development lengths; • Adjusted spacing limits for crack control and skin reinforcement; • Changed limit on spiral reinforcement used for confinement from 60,000 to 100,000 psi; • Permitted an alternative design method for torsion; • Made code more consistent throughout in relation to strength reduction factors, load factors, and the adoption of the unified design approach; • Clarified lap splices and development of flexural reinforcement requirements in special reinforced concrete structural walls; • Provided shear reinforcement requirements for slab-column connections in structures in regions of high seismic risk; and • Clarified and modified Appendix D REVISIONS TO ACI 318-02, “BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE AND COMMENTARY” REPORTED BY ACI COMMITTEE 318 – STANDARD BUILDING CODE James K Wight (Chair) Basile G Rabbat (Secretary) Voting Members Sergio M Alcocer Florian G Barth Roger J Becker Kenneth B Bondy John E Breen James R Cagley Michael P Collins W Gene Corley Charles W Dolan Anthony E Fiorato Catherine E French Luis E Garcia S.K Ghosh Lawrence G Griffis David P Gustafson D Kirk Harman James R Harris Neil M Hawkins Terence C Holland Kenneth C Hover Phillip J Iverson James O Jirsa Dominic J Kelly Gary J Klein Ronald Klemencic Cary S Kopczynski H S Lew Colin L Lobo Robert F Mast Steven L McCabe W Calvin McCall Jack P Moehle Myles A Murray Julio A Ramirez Thomas C Schaeffer Stephen J Seguirant Roberto Stark Eric M Tolles Thomas D Verti Sharon L Wood Loring A.Wyllie FernandoV Yanez SubCommittee Members Neal S Anderson Mark A Aschheim John F Bonacci JoAnn P Browning Nicholas J Carino Ronald A Cook Juan Pablo Covarrubias Robert J Frosch Harry A Gleich R Doug Hooton L S Paul Johal Michael E Kreger Daniel A Kuchma LeRoy A Lutz James G MacGregor Joe Maffei Denis Mitchell Vilas S Mujumdar Suzanne D Nakaki Theodore L Neff Andrzej S Nowak Randall W Poston Bruce W Russell Guillermo Santana Andrew Scanlon John F Stanton Fernando R Stucchi Raj Valluvan John W Wallace Consulting Members C Raymond Hays Richard C Meininger Charles G Salmon Pertinent discussion will be published in a future issue of Concrete International if received no later than September1, 2004 Comments should be directed to Todd R Watson, Manager, Technical Documents, American Concrete Institute, P.O Box 9094, Farmington Hills, MI 48333-9094, or via e-mail at pubcomments@concrete.org GENERAL All notation sections have been removed from the beginning of each chapter and consolidated into one list in Chapter PREFACE The code portion of this document covers the proper design and construction of buildings of structural concrete used in buildings and where applicable in non-building structures The code has been written in such form that it may be adopted by reference in a general building code and earlier editions have been widely used in this manner Among the subjects covered are: The quality and testing Uses of the code include adoption by reference in general building codes, and earlier editions have been widely used in this manner The code is written in a format that allows such reference without change to its language Therefore, background details or suggestions for carrying out the requirements or intent of the code portion cannot be included The commentary is provided for this purpose Some of the considerations of the committee in developing the code portion are discussed within the commentary, with emphasis given to the explanation of new or revised provisions Much of the research data referenced in preparing the code are cited for the user desiring to study individual questions in greater detail Other documents that provide suggestions for carrying out the requirements of the code are also cited Because the ACI Building Code is written as a legal document so that it may be adopted by reference in a general building code, it cannot present background details or suggestions for carrying out its requirements or intent It is the function of this commentary to fill this need The commentary discusses some of the considerations of the committee in developing the code with emphasis given to the explanation of new or revised provisions that may be unfamiliar to code users References to much of the research data referred to in preparing the code are cited for the user desiring to study individual questions in greater detail Other documents that provide suggestions for carrying out the requirements of the code are also cited Reason Statement The preface language has been incorrectly interpreted to mean that the only reason Committee 318 writes the code portion is for adoption into a general building code The revision removes this confusion Keywords T-beams; torsion; walls; water; welded wire reinforcement fabric Reason Statement This change is to modify the term “welded wire fabric ” to “welded wire reinforcement” to be consistent with current ASTM specifications for A 185 and A 497, plain and deformed, welded wire reinforcement, respectively TEXT BOX BEFORE INTRODUCTION The 2002 ACI Building Code and Commentary are presented in a side-by-side column format, with code text placed in the left column and the corresponding commentary text aligned in the right column To further distinguish the Code from the Commentary, the Code has been printed in Helvetica, the same type face in which this paragraph is set Vertical lines in the margins indicate changes from ACI 318-99, including nontechnical changes such as a new section or equation number the previous edition This paragraph is set in Times Roman, and all portions of the text exclusive to the Commentary are printed in this type face Commentary section numbers are preceded by an “R” to further distinguish them from Code section numbers Vertical lines in the margins indicate changes from ACI 318-99, including nontechnical changes such as a new section or equation number the previous version Reason Statement Editorial clarification INTRODUCTION First paragraph This commentary discusses some of the considerations of Committee 318 in developing the provisions contained in “Building Code Requirements for Structural Concrete (ACI 318-025),” hereinafter called the code or the 20025 code Emphasis is given to the explanation of new or revised provisions that may be unfamiliar to code users In addition, comments are included for some items contained in previous editions of the code to make the present commentary independent of the commentary for ACI 318-99 previous editions Comments on specific provisions are made under the corresponding chapter and section numbers of the code Third paragraph As the name implies, “Building Code Requirements for Structural Concrete (ACI 318-02)” is meant to be used as part of a legally Reason Statement Editorial clarification Eighth paragraph … of each of the parties in usual construction General references requiring compliance with the code in the job project specifications should be avoided since the contractor is rarely in a position to accept responsibility for design details or construction requirements that depend on a detailed knowledge of the design Designbuild construction contracts, however, typically combine the design and construction responsibility Generally, the drawings, In part, this can be accomplished by reference to specific code sections in the job project specifications Other ACI publications Reason Statement Design-build contractors accept responsibility for design details or construction requirements that depend on a detailed knowledge of the design, but they have a contractual agreement to so Ninth Paragraph It is desirable recommended to have testing and certification programs for “Standard Specification for Agencies Engaged in the Testing and/or Inspection of Materials Used in Construction” (ASTM E 329-00b 02) Reason Statement To update referenced standards Design Aids “Structural Welded Wire Reinforcement Manual of Standard Practice,” Wire Reinforcement Institute, Findlay, Ohio, 4th Edition, Apr 1992, 31 pp (Describes welded wire reinforcement fabric material Reason Statement Refer to the reason statement given in keywords CHAPTER R1.1 The American Concrete Institute “Building Code Requirements for Structural Concrete (ACI 3180205),” referred to as the code, provides minimum requirements for structural concrete design or construction The 20025 edition of the code revised the previous standard “Building Code Requirements for Structural Concrete (ACI 318-9902).” This standard Prestressed concrete is Chapter 21 In the 1999 code and earlier editions The Alternate Design Method of the 1999 code may be used in place of applicable sections of the 2002 this code Appendix A of the code Appendix B of the 2002 this code contains provisions for reinforcement limits based on 0.75 ρ b , determination of the strength reduction factor φ , and moment Reason Statement Editorial clarification R1.1.6 R1.1.6—Detailed recommendations for design and construction of soil-supported slabs and floors that not transmit vertical loads or lateral forces from other portions of the structure to the soil, and residential post-tensioned slabs-on-ground, are given in the following publications: “Design of Slabs on Grade” reported by ACI Committee 360.1.a (Presents information on the design of slabs on grade, primarily industrial floors and the slabs adjacent to them The report addresses the planning, design, and detailing of the slabs Background information on design theories is followed by discussion of the soil support system, loadings, and types of slabs Design methods are given for plain concrete, reinforced concrete, shrinkage-compensating concrete, and post-tensioned concrete slabs.) “Design and Construction of Post-Tensioned Slabs-on-Ground” PTI1.b (Provides recommendations for post-tensioned slab-on-ground foundations Presents guidelines for soil investigation, design and construction of post-tensioned residential and light commercial slabs on expansive or compressible soils.) Add two new references, and renumber existing references 1.a ACI Committee 360, “Design of Slabs on Grade (ACI 360R-92[Reapproved 1997]),” American Concrete Institute, Farmington Hills, MI, 1997, 57 pp Also Manual of Concrete Practice, Part 5, 2004 1.b PTI, “Design and Construction of Post-Tensioned Slabs on Ground,” 2nd Edition, Post-Tensioning Institute, Phoenix, AZ, Oct 1996, 90 pp Reason Statement Inform ACI 318 code users of documents applicable to design of non-structural, soil-supported slabs and floors R1.1.8.3 R1.1.8.3 — Seismic risk levels (Seismic Zone Maps) The 2000 and 2003 editions of the “International Building Code” (IBC)1.14, 1.xx and the 2003 NFPA 5000 “Building Construction and Safety Code” 1.yy also uses the two criteria of the NBC and SBC and also considers the effects of soil amplification on the ground motion when assigning seismic risk Under the IBC and NFPA codes, each structure is assigned a Seismic Design Category (SDC) Among its several uses, it the SDC triggers different levels of detailing requirements In the absence of a general building code Seismic ground-motion maps or zoning maps, such as recommended in References 1.10xx, 1.15, and 1.16, are suitable for correlating seismic risk Table R1.1.8.3—Correlation between seismic-related terminology in model codes Level of seismic risk or assigned seismic performance or design categories as defined in the code section Code, standard, or resource document and edition Low Moderate/intermediate High (21.2.1.2) (21.2.1.3) (21.2.1.4) International Building Code IBC 2000, 2003; NFPA 5000, 2003; SDC* A, B SDC C SDC D, E, F ASCE 7-98, 7-02; NEHRP 1997, 2000 BOCA National Building Code 1993, 1996, 1999; Standard Building SPC C SPC D, E SPC^ A, B Code 1994, 1997, 1999; ASCE 7-93, 7-95, 7-98; NEHRP 1991, 1994 Uniform Building Code 1991, 1994, Seismic Seismic Seismic 1997 Zone 0, Zone Zone 3,4 *SDC = Seismic Design Category as defined in code, standard, or resource document ^ SPC = Seismic Performance Category as defined in code, standard, or resource document Add two new references: 1.xx “International Building Code,” International Code Council, Falls Church, VA, 2003 1.yy “Building Construction and Safety Code – NFPA 5000,” National Fire Protection Association, Quincy, MA, 2003 Reason Statement To update referenced standards and resource documents R1.3 – Inspection— Qualification of the inspectors can be obtained from a certification program, such as the ACI Certification Program for Concrete Construction Special Inspector.certification program for Reinforced Concrete Inspector sponsored by ACI, International Conference of Building Officials (ICBO), Building Officials and Code Administrators International (BOCA), and Southern Building Code Congress International (SBCCI) R1.3.1, second paragraph— and postplacement operations through the ACI Inspector Certification Program: Concrete Construction Special Inspector.Reinforced Concrete Special Inspector program sponsored by ACI, ICBO, BOCA, and SBCCI or equivalent R1.3.2, second paragraph— and to see that tests for quality assurance control are being made as specified Reason Statement To update of titles and clarify intent CHAPTER Chapter — Notation and Definitions 2.1 (Note: In previous editions of the code, a list of notation was given in Appendix E For the 2005 edition, the notation is being moved into a new section 2.1 Rather than show the new section entirely underlined, the strikeout and underline for section 2.1 indicates revisions to the Appendix E of ACI 318-02, which shows how the notation has been revised throughout the code.) 2.1 – Code notation The terms in this list are used in the code and as needed in the commentary a a av = depth of equivalent rectangular stress block as defined in 10.2.7.1, in., Chapters 10, 12 Chapter 10 = shear span, equal to distance between from center of concentrated load and to either (a) face a = Ab = = = Ab Abrg of support for continuous or cantilevered members, or (b) center of support for simplysupported members, in., Chapter 11, Appendix A shear span, equal to the distance between a load and a support in a structure, in., Appendix A area of an individual horizontal bar or wire, in.2, Chapters 10, 12 area of an individual bar, in.2, Chapter 12 bearing area of the head of stud or anchor bolt, in.2, Appendix D Acp = area of concrete section resisting shear transfer, in.2, Chapter 11 = area of core of spirally reinforced compression member measured to outside diameter of spiral, in.2, Chapter 10 = area of contact surface being investigated for horizontal shear, in.2, Chapter 17 = larger gross cross-sectional area of the slab-beam strips of the two orthogonal equivalent frames intersecting at a column of a two-way slab, in.2, Chapter 18 = cross-sectional area of a structural member measured out-to-out of transverse reinforcement, in.2, Chapters 10, 21 = area enclosed by outside perimeter of concrete cross section, in.2, See see 11.6.1, Chapter 11 Ac Acs = the effective cross-sectional area at one end of a strut in a strut-and-tie model, taken A Act perpendicular to the axis of the strut, in.2, Appendix A = area of that part of cross section between the flexural tension face and center of gravity of Ac Ac Ac Acf Ach Acv Acp Acw gross section, in.2, Chapter 18 = gross area of concrete section bounded by web thickness and length of section in the direction of shear force considered, in.2, Chapter 21 = area of concrete section, resisting shear, of an individual pier, or horizontal wall segment, or Ag coupling beam resisting shear, in.2, Chapter 21 = area of reinforcement in bracket or corbel resisting factored moment, [Vua + Ν uc (h − d)] , in.2, see 11.9, Chapter 11 = gross area of concrete section, in.2 For a hollow section, Ag is the area of the concrete only Ag and does not include the area of the void(s)., See see 11.6.1, Chapters 11 9-11, 14-16, 21, 22, Appendix B Appendices B, C = gross area of column, in.2, Chapter 16 Ag = gross area of section, in.2, Chapters 9, 10, 14, 21, 22, 15, Appendix B Ah = total area of shear reinforcement parallel to flexural primary tension reinforcement in a corbel or bracket, in.2, see 11.9, Chapter 11 = effective cross-sectional area within a joint, See 21.5.3.1, in a plane parallel to plane of Af Aj reinforcement generating shear in the joint, in.2, The joint depth shall be the overall depth of Al Al ,min the column Where a beam frames into a support of larger width, the effective width of the joint shall not exceed the smaller of: (a) beam width plus the joint depth (b) twice the smaller perpendicular distance from the longitudinal axis of the beam to the column side See see 21.5.3.1, Chapter 21 = total area of longitudinal reinforcement to resist torsion, in.2, Chapter 11 = minimum area of longitudinal reinforcement to resist torsion, in.2, see 11.6.5.3, Chapter 11 AN ANc = area of reinforcement in bracket or corbel resisting tensile force Nuc , in.2, see 11.9, Chapter 11 = projected concrete failure area of an a single anchor or group of anchors, for calculation of ANo ANco strength in tension, in.2, as defined in see D.5.2.1 AN shall not be taken greater than nANo See Fig RD.5.2.1(b), Appendix D = projected concrete failure area of one a single anchor, for calculation of strength in tension An Anz when if not limited by edge distance or spacing, in.2, as defined in see D.5.2.1 Fig RD.5.2.1(a), Appendix D = area of a face of a nodal zone or a section through a nodal zone, in.2, Appendix A An Ao Aoh Aps = gross area enclosed by shear flow path, in.2, Chapter 11 = area enclosed by centerline of the outermost closed transverse torsional reinforcement, in.2, Chapter 11 = area of prestressed reinforcement prestressing steel in flexural tension zone, in.2, Chapters As = As = = = As As′ As′ Asc Ase Ase Ash Asi = = 11, 18, Appendix B area of nonprestressed longitudinal tension reinforcement, in.2, Chapters 8, 10, 11, 12 10-12, 14, 15, 18, Appendix B area of longitudinal tension reinforcement in wall segment, in.2, Chapter 14 area of tension reinforcement, in.2, Appendix B area of longitudinal compression reinforcement, in.2, Chapters 8, 9, 18, Appendices Appendix A, B area of compression reinforcement in a strut, in.2, Appendix A area of primary tension reinforcement in a corbel or bracket, in.2, see 11.9.3.5, Chapter 11 = area of effective longitudinal tension reinforcement in wall segment, in.2, as calculated by Eq (14-8), Chapter 14 = effective cross-sectional area of anchor, in.2, Appendix D = total cross-sectional area of transverse reinforcement (including crossties) within spacing s and perpendicular to dimension hc bc , in.2, Chapter 21 = total area of surface reinforcement at spacing si in the ith layer crossing a strut, with reinforcement at an angle α i to the axis of the strut, in.2, Appendix A Asl As,min = effective cross-sectional area of expansion or undercut anchor sleeve, if sleeve is within shear plane, in.2, Appendix D = minimum amount area of flexural reinforcement, in.2, See see 10.5, Chapter 10 Ast At Asx At Aps Atp Atr Ast Ats = total area of nonprestressed longitudinal reinforcement, (bars or steel shapes), in.2, Chapter 10 Chapters 10, 21 = area of structural steel shape, pipe, or tubing in a composite section, in.2, Chapter 10 = area of one leg of a closed stirrup resisting torsion within a distance spacing s , in.2, Chapter 11 = area of prestressed reinforcement prestressing steel in a tie, in.2, Appendix A = total cross-sectional area of all transverse reinforcement which is within the spacing s and which that crosses the potential plane of splitting through the reinforcement being developed, in.2, Chapter 12 = area of nonprestressed reinforcement in a tie, in.2, Appendix A AV AVc = area of shear reinforcement within a distance spacing s , in.2, Chapters 11, 12, 17 = area of shear reinforcement within a distance s , or area of shear reinforcement perpendicular to flexural tension reinforcement within a distance s for deep flexural members, in.2, Chapter 11 = area of ties within a distance s , in.2, Chapter 17 = projected concrete failure area of an a single anchor or group of anchors, for calculation of AVo AVco strength in shear, in.2, as defined in see D.6.2.1 and AV shall not be taken greater than nAVo See RD.6.2(b), Appendix D = projected concrete failure area of one a single anchor, for calculation of strength in shear, Av Av Av Avd = Avf Avh = = Av ,min = Aw A1 A2 b b bc when if not limited by corner influences, spacing, or member thickness, in.2, as defined in see D.6.2.1 and See Fig RD.6.2(a), Appendix D total area of reinforcement in each group of diagonal bars in a diagonally reinforced coupling beam, in.2, Chapter 21 area of shear-friction reinforcement, in.2, Chapter 11 area of shear reinforcement parallel to flexural tension reinforcement within a distance spacing s2 , in.2, Chapter 11 minimum area of shear reinforcement within spacing s , in.2, see 11.5.5.3 11.5.6.3 and 11.5.6.4, Chapter 11 = area of an individual wire to be developed or spliced, in.2, Chapter 12 = loaded area, in.2, Chapters 10, 22 = the area of the lower base of the largest frustum of a pyramid, cone, or tapered wedge contained wholly within the support and having for its upper base the loaded area, and having side slopes of vertical to horizontal, in.2, Chapters 10, 22 = width of compression face of member, in., Chapters 9-11, 18, 21 10, Appendix B = effective compressive flange width of a structural member, in., Chapter 21 = cross-sectional dimension of column core measured center-to-center of outer legs of the transverse reinforcement comprising area Ash , in., Chapter 21 bo b bs = perimeter of critical section for shear in slabs and footings, in., see 11.12.1.2, Chapters 11, 22 = width of member strut, in., Chapter 22, Appendix A Reason Statement Refer to the reason statement given in D.5.2.2 D.5.2.7 Renumber existing D.5.2.7 to D.5.2.8 and add new D.5.2.7 D.5.2.7 The modification factor for post-installed anchors designed for uncracked concrete in accordance with D.5.2.6 without supplementary reinforcement to control splitting is: ψ cp,N = 1.0 if ca,min ≥ cac (D-12) ψ cp,N = ca,min cac ≥ 1.5hef cac if ca,min < cac (D-13) where the critical distance, cac , is defined in D.8.6 For all other cases, including cast-in anchors, ψ cp,N shall be taken as 1.0 Note: renumber Eq (D-12) through (D-29) and references to these equations to Eq (D-14) to D-31) Reason Statement Refer to the reason statement given in D.5.2.1 RD.5.2.7 Add new section: RD.5.2.7 The design provisions in D.5 are based on the assumption that the basic concrete breakout strength can be achieved if the minimum edge distance, ca ,min , equals 1.5hef However, test resultsD.XX indicate that many torque-controlled and displacement-controlled expansion anchors and some undercut anchors require minimum edge distances exceeding 1.5hef to achieve the basic concrete breakout strength when tested in uncracked concrete without supplementary reinforcement to control splitting When a tension load is applied, the resulting tensile stresses at the embedded end of the anchor are added to the tensile stresses induced due to anchor installation, and splitting failure may occur before reaching the concrete breakout strength defined in D.5.2.1 To account for this potential splitting mode of failure, the basic concrete breakout strength is reduced by a factor ψ cp ,N if ca ,min is less than the critical edge distance cac If supplementary reinforcement to control splitting is present or if the anchors are located in a region where analysis indicates cracking of the concrete at service loads, then the reduction factor ψ cp,N is taken as 1.0 The presence of supplementary reinforcement to control splitting does not affect the selection of Condition A or B in D.4.4 or D.4.5 D.XX Asmus, J “Verhalten von Befestigungen bei der Versagensart Spalten des Betons (Behavior of Fastenings with the Failure Mode Splitting of Concrete),” Disseratation, Universität Stuttgart, Germany, 1999 Reason Statement Refer to the reason statement given in D 5.2.1 70 D.5.3.4 D.5.3.4 — The pullout strength in tension of a single headed stud or headed bolt, N p , for use in Eq (D124), shall not Reason Statement Editorial clarification RD.5.3.4 RD.5.3.4 — Equation (D-135) corresponds to the load at which the concrete under the anchor head begins Reason Statement Editorial clarification D.5.3.5 RD.5.3.5 — The pullout strength in tension of a single hooked bolt, N p , for use in Eq (D-124) shall Reason Statement Editorial clarification RD.5.3.5 RD.5.3.5 — Equation (D-146) for hooked bolts was developed by Lutz based on the results of Reference Reason Statement Editorial clarification D.5.4.2 where s is spacing of the outer anchors along the edge in the group; and N sb is obtained from Eq (D157) without modification for a perpendicular Reason Statement Editorial clarification D.6.1.2 D.6.1.2— The nominal strength V s of an single anchor or group of anchors in shear, Vsa , shall not exceed (a) through (c): (a) for cast-in headed stud anchors Vsa = nAse futa V s = nΑ se fut (D-19) 71 where n is the number of anchors in the group and futa shall not be taken greater than the smaller of 1.9fya and 125,000 psi.where fut shall not be taken greater than 1.9fy or 125,000 psi (b) for cast-in headed bolt and hooked bolt anchors and for post-installed anchors where sleeves not extend through the shear plane Vsa = n0.6 Ase futa V s = n0.6Α se fut (D-20) where n is the number of anchors in the group and futa shall not be taken greater than the smaller of 1.9fya and 125,000 psi where fut shall not be taken greater than 1.9fy or 125,000 psi (c) for post-installed anchors where sleeves extend through the shear plane, Vsa shall be based on the results of tests performed and evaluated according to ACI 355.2 Alternatively, Eq (D-20) shall be permitted to be used V s = n( 0.6Α se fut + 0.4 sl futsl ) (D-19) where fut shall not be taken greater than 1.9fy or 125,000 psi Reason Statement To require testing if the contribution of post-installed anchor sleeves to shear strength is considered D.6.2.1 D.6.2.1—The nominal concrete breakout strength, Vcb or Vcbg , in shear of an a single anchor or group of anchors shall not exceed: (a) for shear force perpendicular to the edge on a single anchor: Vcb = AV ψ 6ψ 7Vb AVo Vcb = AVc ψ ed ,V ψ c,V Vb AVco (D-21) (b) for shear force perpendicular to the edge on a group of anchors: Vcbg = AV ψ 5ψ 6ψ 7Vb AVo Vcbg = AVc ψ ec,V ψ ed ,V ψ c,V Vb AVco (D-22) (c) for shear force parallel to an edge, Vcb or Vcbg shall be permitted to be twice the value for of the shear force determined from Eq (D-21) or (D-22), respectively, with the shear force assumed to act perpendicular to the edge and with ψ6 ψ ed ,V taken equal to 1.0 (d) for anchors located at a corner, the limiting nominal concrete breakout Factors ψ ec,V , ψ ed ,V , and ψ c,V are defined in D.6.2.5, D.6.2.6, and D.6.2.7, respectively V b is the basic concrete breakout strength value for a single anchor Av AVc is the projected area of the failure surface on 72 the side of the concrete member at its edge for a single anchor or a group of anchors It shall be permitted to evaluate AVc this area as the base of a truncated half pyramid projected on the side face of the member where the top of the half pyramid is given by the axis of the anchor row selected as critical The value of c ca1 shall be taken as the distance from the edge to this axis Av AVc shall not exceed nAVo nAVco , where n is the number of anchors in the group AVo AVco is the projected area for a single anchor in a deep member with a distance from edges equal or greater than 1.5 ca1 remote from edges in the direction perpendicular to the shear force It shall be permitted to evaluate AVco this area as the base of a half pyramid with a side length parallel to the edge of 3c 3ca1 and a depth of 1.5c 1.5ca1 : Α vo = 4.5 (c1 )2 AVco = 4.5 ( ca1 ) (D-23) Where anchors are located at varying distances from the edge and the anchors are welded to the attachment so as to distribute the force to all anchors, it shall be permitted to evaluate the strength based on the distance to the farthest row of anchors from the edge In this case, it shall be permitted to base the value of c ca1 on the distance from the edge to the axis of the farthest anchor row that is selected as critical, and all of the shear shall be assumed to be carried by this critical anchor row alone Reason Statement To clarify how to evaluate the shear breakout strength when anchors are loaded parallel to an edge RD.6.2.1 First paragraph The shear strength equations were developed from the CCD method They assume a breakout cone angle of approximately 35 degrees (See Fig RD.4.2.2(b)), and consider fracture mechanics theory The effects of multiple anchors, spacing of anchors, edge distance, and thickness of the concrete member on nominal concrete breakout strength in shear are included by applying the reduction factor ΑV / ΑVo ΑVc / ΑVco in Eq (D-201) and (D-212), and ψ ψ ec ,V in Eq (D-212) For anchors far from the edge, D.6.2 usually will not govern For these cases, D.6.1 and D.6.3 often govern Fig RD.6.2.1(a)—Change c1 to ca1 and AVo to AVco Fig RD.6.2.1(b)—Change c1 to ca1 , c2 to ca , h to , and AV to AVc Fig RD.6.2.1(d)—Change c1 to ca1 and c2 to ca Second paragraph Fig RD.6.2.1(a) shows AVo AVco and the development of Eq (D-223) AVo AVco is the maximum projected area for multiple anchor arrangements AV AVc approximates the full surface area of the breakout cone for the particular arrangement of anchors Because AV AVc is the total projected area for a group of anchors, and AVo AVco is the area for a single anchor 73 Reason Statement To consolidate similar terms as appropriate and eliminate unnecessary terms Third paragraph The assumption shown in the upper right example of Fig RD.6.2.1(b), with the case for two anchors perpendicular to the edge, is a conservative interpretation of the distribution of the shear force on an elastic basis When using Eq (D-22) for anchor groups loaded in shear, both assumptions for load distribution illustrated in examples on the right side of Fig RD.6.2.1(b) should be considered because the anchors nearest the edge could fail first or the whole group could fail as a unit with the failure surface originating from the anchors farthest from the edge If the anchors are welded to a common plate, when the anchor nearest the front edge begins to form a failure cone, shear load would be transferred to the stiffer and stronger rear anchor For this reason, anchors welded to a common plate not need to consider the failure mode shown in the upper right figure of Fig RD.6.2.1(b) For cases where nominal strength is not controlled by ductile steel elements, D.3.1 requires that load effects be determined by elastic analysis The PCI Design Handbook approachD.17 suggests in Section 6.5.2.2 that the increased capacity of the anchors away from the edge be considered Because this is a reasonable approach, assuming that the anchors are spaced far enough apart so that the shear failure surfaces not intersect,D.11 D.6.2 allows such a procedure If the failure surfaces not intersect, as would generally occur if the anchor spacing s is equal to or greater than 1.5c1 1.5ca1 , then after formation of the near-edge failure surface, the higher capacity of the farther anchor would resist most of the load In second “note,” delete “that applies only where anchors are rigidly connected to the attachment.” Also, add a new last sentence to the note: “only this assumption needs to be considered when anchors are rigidly connected to the attachment.” Reason Statement To provide guidance for computing the nominal shear concrete breakout strength for anchor groups Last paragraph The case of shear force parallel to an edge is shown in Fig RD.6.2.1(c) A special case can arise with shear force parallel to the edge near a corner In the example of a single anchor near a corner (See Fig RD.6.2.1(d)), the provisions for shear in the direction of the load should be checked in addition to the provisions for shear in the direction parallel to the edge where the edge distance to the side c2 is 40 percent or more of the distance c1 in the direction of the load, the shear strength parallel to that edge can be computed directly from Eq (D-20) and (D-21) using c1 in the direction of the load Reason Statement To clarify how to evaluate the shear breakout strength when anchors are loaded parallel to an edge D.6.2.4 D.6.2.4— For the special case ofWhere anchors are influenced by three or more edges, the value of edge distance ca1 c used in Eqs (D-23), (D-22), (D-23), (D-24), (D-25), (D-26) and through (D-28) shall be limited to h / 1.5 not exceed the greatest of: c a /1.5 in either direction, / 1.5 and one-third of the maximum spacing between anchors within the group Reason Statement To clarify computation of shear breakout strength close to three or four edges 74 RD.6.2.4 RD.6.2.4 — For anchors influenced by three or more edges where any edge distance is less than 1.5ca1 1.5 c1, the shear breakout strength computed by the basic CCD Method, which is the basis for Eqs (D-2120) through (D-28)and (D-24), gives safe but misleading overly conservative results These special cases were studied for the Κ MethodD.14 and the problem was pointed out by Lutz.D.20 Similar to Similarly, the approach used for tensile breakouts in D.5.2.3, a correct evaluation of the capacity is determined if the value of ca1 c1 to be used in Eqs Eq (D-2120) to (D-278) is limited to the maximum of ca2 /1.5 in each direction, / 1.5 h/1.5, and one-third of the maximum spacing between anchors within the group The limit on ca1 c1 of at least one-third of the maximum spacing between anchors within the group prevents the designer from using a calculated strength based on individual breakout prisms for a group anchor configuration This approach is illustrated in Figure RD.6.2.4 In this example, the limit on the value of ca1 is the largest of ca2 /1.5 in either direction, / 1.5 , and one-third the maximum spacing between anchors for anchor groups results in c’a1 = 5.33 in For this example, this would be the proper value to be used for ca1 in computing Vcb or Vcbg even if the actual edge distance that the shear is directed toward is larger The requirement of D.6.2.4 may be visualized by moving the actual concrete breakout surface originating at the actual ca1 toward the surface of the concrete in the direction of the applied shear load The value of ca1 used in Eq (D-21) to (D28) is determined when either: (a) the outer boundaries of the failure surface first intersect a free edge or (b) the intersection of the breakout surface between anchors within the group first intersects the surface of the concrete For the example shown in Fig RD.6.2.4, point “A” shows the intersection of the assumed failure surface for limiting ca1 with the concrete surface 75 Vn Actual failure surface Actual failure surface Point A Point A c'a1 in in in in Assumed failure surface for limiting ca1 The actual ca1 = 12 in but two orthogonal edges ca2 and h are ≤ 1.5 ca1 therefore the limiting value of ca1 (shown as c'a1 in the figure) is the larger of ca2,max/1.5, h/1.5 and one-third of the maximum spacing for an anchor group: c'a1 = max (7/1.5, 8/1.5, 9/3) = 5.33 in Therefore, use c'a1 = 5.33 in in Eq (D-20) to (D-27) including the calculation of Avc: Avc = (5 + + 7)(1.5(5.33)) = 168 in.2 (that is, the cross-sectional area of the member) Point A shows the intersection of the assumed failure surface for limiting ca1 with the concrete surface Fig RD.6.2.4—Shear when anchors are influenced by three or more edges Reason Statement Refer to the reason statement given in D.6.2.4 D.6.2.5 D.6.2.5— The modification factor for eccentrically loaded anchor groups loaded eccentrically in shear is ψ5 = 1 ≤1 ≤ ψ ec,V = 2e v′  2ev′  1+  1+  3c 3ca1   (D-26) Equation (D-25) is valid for ev′ ≤ s / If the loading on an anchor group is such that only some anchors are loaded in shear in the same direction, only those anchors that are loaded in shear in the same direction shall be considered when determining the eccentricity of e’v for use in Eq (D-26) and for the calculation of Vcbg in Eq (D-22) Reason Statement To clarify eccentricity of e’v RD.6.2.5 RD.6.2.5— This section provides a modification factor for an eccentric shear force towards an edge on a group of anchors If the shear load originates above the plane of the concrete surface, the shear should first 76 be resolved as a shear in the plane of the concrete surface, with a moment that may or may not also cause tension in the anchors, depending on the normal force Figure RD.6.2.5 defines the term e v′ for calculating the ψ ec ,V ψ modification factor that accounts for the fact that more shear is applied on one anchor than the others, tending to split the concrete near an edge If e v′ ≤ s / , the CCD procedure is not applicable Reason Statement Refer to the reason statement given in D.6.2.5 D.6.3.1 D.6.3.1—The nominal pryout strength, Vcp or Vcpg shall not exceed for a single anchor: Vcp = kcp Ncb (D-29) for a group of anchors: Vcpg = kcpNcbg (D-30) where kcp = 1.0 for hef < 2.5 in kcp = 2.0 for hef ≥ 2.5 in and Ncb and Ncbg shall be determined from Eq (D-4) and Eq (D-5), respectively, lb Reason Statement Refer to the reason given in “D.1.” D.8 “…shall conform to D.8.1 through D.8.56,…” Reason Statement Refer to the reason statement given in D 5.2.1 D.8.6 Renumber current D.8.6 to D 8.7 and add new D.8.6 D.8.6 Unless determined from tension tests in accordance with ACI 355.2, the critical edge distance, cac , shall not be taken less than: Undercut anchors Torque-controlled anchors Displacement-controlled anchors 2.5hef 4hef 4hef Reason Statement Refer to the reason statement given in D 5.2.1 RD.8.6 Add new section: RD.8.6 The critical edge distance, cac , is determined by the corner test in ACI 355.2 Research has indicated that the corner-test requirements are not met with ca ,min = 1.5hef for many expansion anchors and some undercut anchors because installation of these types of anchors introduces splitting tensile stresses in 77 the concrete that are increased during load application potentially resulting in a premature splitting failure To permit the design of these types of anchors when product specific information is not available, conservative default values for cac are provided Reason Statement Refer to the reason statement given in D.5.2.1 METRIC 2.1 Al ,min = minimum area of longitudinal reinforcement to resist torsion, mm2, see 11.6.5.3, Chapter 11 Asc = area of primary tension reinforcement in a corbel or bracket, mm2, see 11.9.3.5, Chapter 11 Av ,min = minimum area of shear reinforcement within spacing s , mm2, see 11.5.5.3, Chapter 11 bc = cross-sectional dimension of column core measured center-to-center of outer legs of the transverse reinforcement comprising area Ash , mm, Chapter 21 Bu = factored bearing load, N, Chapter 22 cac = critical edge distance required to develop the basic concrete breakout strength of a post- Ep installed anchor in uncracked concrete without supplementary reinforcement to control splitting, mm., see D.8.6, Appendix D = modulus of elasticity of prestressing steel, MPa, see 8.5.3, Chapter Mcr Mcre = moment causing flexural cracking at section due to externally applied loads, mm-N, Chapter Vcpg 11 = factored end moment on compression member at the end at which M2 acts, due to loads that cause appreciable sidesway, calculated using a first-order elastic frame, mm-N, Chapter 10 = nominal concrete pryout strength of a group of anchors, N, see D.6.3, Appendix D hanc = the dimension of anchorage device or single group of closely spaced devices in the direction M2 s of bursting being considered, mm, Chapter 18 10.6.4 10.6.4—The spacing s of reinforcement closest to a surface in tension the tension face, s, shall not exceed that given by s=  280  95 ,000  − 2.5Cc − 2.5c c s = 380 fs  fs  (10-4) but not greater than 300(252/fs) 300(280/fs), where cc is the least distance from surface of reinforcement or prestressing steel to the tension face If there is only one bar or wire nearest to the extreme tension face, s used in (10-4) is the width of the extreme tension face 78 Calculated stress fs (in ksi) in reinforcement closest to the tension face at service load shall be computed as the unfactored moment divided by the product of steel area and internal moment arm It shall be permitted to take fs as 60 percent 2/3 of specified yield strength fy Reason Statement Refer to the reason statement given in R.10.6.1 R10.6.4 R10.6.4—This section was updated in the 2005 edition to reflect the higher service stresses that occur in flexural reinforcement with the use of the load combinations introduced in the 2002 code This section replaces the z factor requirements of the 1995 and previous code editions The maximum bar spacing is now specified directly to control cracking.10.15,10.16,10.17 For the usual case of beams with Grade 420 reinforcement and 50 mm clear cover to the main reinforcement, with fs = 250 MPa 280 MPa, the maximum bar spacing is 300 mm Crack widths in structures are highly variable In codes before the 1999 edition previous codes, provisions Reason Statement Refer to the reason statement given in R.10.6.1 R10.6.7 R10.6.7—For relatively deep flexural members, some reinforcement should be placed near the vertical faces of the tension zone to control cracking in the web.10.16 10.XX, 10.YY (See Fig R10.6.7.) tension reinforcement This section was modified in the 2005 edition to make the skin reinforcement spacing consistent with that of the flexural reinforcement The size of the skin reinforcement is not specified; research has indicated that the spacing rather than bar size is of primary importance.10.YY Bar sizes No 10 to No 16 (or welded wire reinforcement with a minimum area of 210 mm2/m of depth) are typically provided Where the provisions for deep beams, walls, or precast panels require more reinforcement steel, those provisions (along with their spacing requirements) will govern Fig R10.6.7—Skin reinforcement for beams and joists with d h> 910 mm The capital “S” should be replaced with a lowercase “s.” Reason Statement Refer to the reason statement given in 10.6.7 10.9.3 10.9.3— Ratio of spiral reinforcement, ρ s , shall be not less than the value given by  Αg  f′ − 1 c ρ s = 0.45  Αc  fy ρ s = 0.45  79  Ag  f′ − 1 c   Ach  fyt (10-5) where the value of fyt used in Eq (10-5) is the specified yield strength of spiral reinforcement but not more thanshall not exceed 420 700 MPa For fyt greater than 420 MPa, lap splices according to 7.10.4.5(a) shall not be used Reason Statement Refer to the reason statement given in 9.4 R10.9.3 Add at the end of the commentary Research[10.x,xx] has indicated that 700 MPa yield strength reinforcement can be used for confinement For the 2005 code the limit in yield strength for spiral reinforcement has been increased from 420 to 700 MPa Reason Statement Refer to the reason statement given in 9.4 18.3.3 Revise last sentence as follows: Prestressed two-way slab systems shall be designed as Class U with ft ≤ 0.5 fc' Reason Statement To limit the permissible flexural tensile stress in two-way prestressed slabs to the same value it was in previous codes 21.2.5 21.2.5—Reinforcement resisting earthquake-induced flexural and axial forces in frame members and in structural wall boundary elements shall comply with ASTM A 706M ASTM A 615M Grades 300 and 420 reinforcement shall be permitted in these members if: (a) The actual yield strength based on mill tests does not exceed fy the specified yield strength by more than 120 MPa (retests shall not exceed this value by more than an additional 20 MPa); and (b) The ratio of the actual ultimate tensile strength to the actual tensile yield strength is not less than 1.25 The value of fyt for transverse reinforcement including spiral reinforcement shall not exceed 420 MPa psi Reason Statement Maximum allowable yield stress for confinement reinforcement is increased to 420 MPa for most applications The exception for structures in regions of high seismic risk or assigned to high seismic design or performance categories is because this application is under current study by the committee The change to Section 10.9.3 allowing fyt of 420 MPa for spiral reinforcement does not apply to Chapter 21 21.11.5 Add new section: 80 21.11.5—For slab-column connections of two-way slabs without beams, slab shear reinforcement satisfying the requirements of 11.12.3 and providing Vs not less than 0.29 f ' c bo d shall extend at least four times the slab thickness from the face of the support, unless either (a) or (b) is satisfied: (a) The requirements of 11.12.6 using the design shear Vu and the induced moment transferred between the slab and column under the design displacement; (b) The design story drift ratio does not exceed the larger of 0.005 and [0.035 – 0.05(Vu/φVc)] Design story drift ratio shall be taken as the larger of the design story drift ratios of the adjacent stories above and below the slab-column connection Vc is defined in 11.12.2 Vu is the factored shear force on the slab critical section for two-way action, calculated for the load combination 1.2D + 1.0L + 0.2S It shall be permitted to reduce the load factor on L to 0.5 in accordance with 9.2.1(a) Reason Statement Refer to the reason statement given in 21.1 D.5.2.2 D.5.2.2— The basic concrete breakout strength Nb of a single anchor in tension in cracked concrete, Nb , shall not exceed 1.5 1.5 Nb = kc fc′ hef Nb = k fc′ hef (D-7) where kc k = 10 for cast-in anchors; and kc k = for post-installed anchors The value of kc for post-installed anchors shall be permitted to be increased above based on ACI 355.2 product-specific tests, but shall in no case exceed 10 Alternatively, for cast-in headed studs and headed bolts with 280 mm ≤ hef ≤ 635 mm, the basic concrete breakout strength of a single anchor in tension in cracked concrete Nb shall not exceed Reason Statement To clarify design of post-installed anchors used in cracked and uncracked concrete in the body of the code rather than in the commentary RD.5.2.3 RD.5.2.3 — For anchors located influenced by three or more edges where any edge distance is less than 1.5 hef from three or more edges, the tensile breakout strength computed by the ordinary CCD Method, which is the basis for Eq.(D-47) to and (D-118), gives misleading overly conservative resultsD.20 This occurs because the ordinary definitions of ANc / ANco not correctly reflect the edge effects This problem is corrected by limiting the value of h ef used in Eq (D-4) through (D-11) to cmax / 1.5ca,max / 1.5, however, where ca,maxc max is the largest of the influencing edge distances that are less than or equal to the actual 1.5 hef In no case should ca,max be taken less than one-third of the maximum spacing between anchors within the group this problem is corrected The limit on hef of at least one-third of the maximum 81 spacing between anchors within the group prevents the designer from using a calculated strength based on individual breakout prisms for a group anchor configuration As shown by Lutz,D.20 this limiting value of hef is to be used in Eq (D-6) to (D-11) This approach is best understood when applied to an actual case illustrated in Figure RD.5.2.3 Figure RD.5.2.3 shows how the failure surface has the same area for any embedment beyond the proposed limit on hef (taken as h’ef in the figure) In this example, the proposed limit on the value of hef to be used in the computations where hef = ca,maxcmax / 1.5 , results in hef = h’ef = 100 mm/1.5 = 2.67 in For this example, this would be the proper value to be used for hef in computing the resistance even if the actual embedment depth were larger The requirement of D.5.2.3 may be visualized by moving the actual concrete breakout surface, which originates at the actual hef, toward the surface of the concrete parallel to the applied tension load The value of hef used in Eq (D-4) to (D-11) is determined when either: (a) the outer boundaries of the failure surface first intersect a free edge: or (b) the intersection of the breakout surface between anchors within the group first intersects the surface of the concrete For the example shown in Fig RD.5.2.3, point “A” defines the intersection of the assumed failure surface for limiting hef with the concrete surface Fig RD.5.2.3—Tension in narrow members Reason Statement Refer to the reason statement given in D.5.2.3 82 D.5.2.6 D.5.2.6— When anFor anchors is located in a region of a concrete member where analysis indicates no cracking ( ft < f r ) at service load levels, the following modification factor shall be permitted: ψ c,N ψ = 1.25 for cast-in anchors ψ c,N ψ = 1.4 for post-installed anchors, where the value of kc used in Eq (D-7) is Where the value of kc used in Eq (D-7) is taken from the ACI 355.2 product evaluation report for postinstalled anchors qualified for use only in both cracked and uncracked concrete, the values of kc and ψc,N shall be based on the ACI 355.2 product evaluation report Where the value of kc used in Eq (D-7) is taken from the ACI 355.2 product evaluation report for postinstalled anchors qualified for use only in uncracked concrete, ψc,N shall be taken as 1.0 When analysis indicates cracking at service load levels, ψ ψ c ,N shall be taken as 1.0 for both cast-in Reason Statement Refer to the reason statement given in D.5.2.2 RD.6.2.4 RD.6.2.4 — For anchors influenced by three or more edges where any edge distance is less than 1.5ca1 1.5 c1 , the shear breakout strength computed by the basic CCD Method, which is the basis for Eq (D-2123) through (D-28)and (D-24), gives safe but misleading overly conservative results These special cases were studied for the Κ MethodD.14 and the problem was pointed out by Lutz.D.20 Similar to Similarly, the approach used for tensile breakouts in D.5.2.3, a correct evaluation of the capacity is determined if the value of ca1 c1 to be used in Eqs Eq (D-2122) to (D-28) is limited to the maximum of c a /1.5 in each direction, / 1.5 h/1.5, and one-third of the maximum spacing between anchors within the group The limit on ca1 c1 of at least one-third of the maximum spacing between anchors within the group prevents the designer from using a calculated strength based on individual breakout prisms for a group anchor configuration This approach is illustrated in Figure RD.6.2.4 In this example, the limit on the value of ca1 is the largest of ca2 /1.5 in either direction, / 1.5 , and one-third the maximum spacing between anchors for anchor groups results in c’a1 = 133 mm For this example, this would be the proper value to be used for ca1 in computing Vcb or Vcbg even if the actual edge distance that the shear is directed toward is larger The requirement of D.6.2.4 may be visualized by moving the actual concrete breakout surface originating at the actual ca1 toward the surface of the concrete in the direction of the applied shear load The value of ca1 used in Eq (D-21) to (D-28) is determined when either: (a) the outer boundaries of the failure surface first intersect a free edge; or (b) the intersection of the breakout surface between anchors within the group first intersects the surface of the concrete For the example shown in Fig RD.6.2.4, point “A” shows the intersection of the assumed failure surface for limiting ca1 with the concrete surface 83 Vn Actual failure surface Actual failure surface ca1= 300 mm Point A c'a1 130 mm 230 mm 180 mm 200 mm Assumed failure surface for limiting ca1 The actual ca1 = 300 mm but two orthogonal edges ca2 and h are ≤ 1.5 ca1 therefore the limiting value of ca1 (shown as c'a1 in the figure) is the larger of ca2,max/1.5, h/1.5 and one-third of the maximum spacing for an anchor group: c'a1 = max (130/1.5, 200/1.5, 180/3) = 133 mm Therefore, use c'a1 = 133 mm in Eq (D-20) to (D-27) including the calculation of Avc: Avc = (130 + 230 + 180)(1.5(13.33)) = 107,700 mm2 (that is, the cross-sectional area of the member) Point A shows the intersection of the assumed failure surface for limiting ca1 with the concrete surface Fig RD.6.2.4—Shear when anchors are influenced by three or more edges Reason Statement Refer to the reason statement given in D.6.2.4 84 ... face in which this paragraph is set Vertical lines in the margins indicate changes from ACI 318- 99, including nontechnical changes such as a new section or equation number the previous edition This... distinguish them from Code section numbers Vertical lines in the margins indicate changes from ACI 318- 99, including nontechnical changes such as a new section or equation number the previous version Reason...REVISIONS TO ACI 318- 02, “BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE AND COMMENTARY” REPORTED BY ACI COMMITTEE 318 – STANDARD BUILDING CODE James K Wight