ACI ITG-6R-2010 Design Guide for the Use of ASTM A1035 A1035M Grade 100 (690) Steel Bars for Structural Concrete.pdf

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1、ACI ITG-6R-10Reported by ACI Innovation Task Group 6Design Guide for the Use ofASTM A1035/A1035M Grade 100 (690)Steel Bars for Structural ConcreteDesign Guide for the Use of ASTM A1035/A1035M Grade 100 (690) Steel Bars for Structural ConcreteFirst PrintingAugust 2010ISBN 978-0-87031-388-2American Co

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10、icsubscription, or reprint and may be obtained by contacting ACI.Most ACI standards and committee reports are gathered together in the annually revised ACI Manual ofConcrete Practice (MCP).American Concrete Institute38800 Country Club DriveFarmington Hills, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-

11、848-3701www.concrete.orgACI ITG-6R-10 was adopted and published August 2010.Copyright 2010, American Concrete Institute.All 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,

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14、 Institute disclaimsany and all responsibility for the stated principles. The Instituteshall not be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocuments. If items found in this document are desired by theArchitect/Engineer to be a part of

15、the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.Design Guide for the Use of ASTM A1035/A1035M Grade 100 (690) Steel Bars for Structural ConcreteReported by ACI Innovation Task Group 6ACI ITG-6R-10This guide provides recommendations on de

16、sign provisions for the use ofASTM A1035/ASTM1035M Grade 100 (690) deformed steel bars forreinforced concrete members. The recommendations address only thoserequirements of ACI 318-08 that limit efficient use of such steel bars. Othercode requirements are not affected.This guide includes a discussio

17、n of the material characteristics of Grade100 (690) ASTM A1035/A1035M deformed steel bars and recommends designcriteria for beams, columns, slab systems, walls, and footings for SeismicDesign Category (SDC) A, B, or C, and also for structural components notdesignated as part of the seismic-force-res

18、isting system for SDC D, E, or F. Keywords: bar; concrete; design; guide; high-strength steel; structural.CONTENTSChapter 1Introduction, p. 21.1Objective1.2Scope1.3Historical perspective and background1.4AvailabilityChapter 2Notation and definitions, p. 42.1Notation2.2DefinitionsChapter 3Material pr

19、operties, p. 53.1Introduction3.2Weights, dimensions, and deformations3.3Specified tensile properties3.4Actual tensile properties3.5Actual compressive properties3.6Chemical compositionChapter 4Beams, p. 94.1Introduction4.2Flexural strength4.3Tension- and compression-controlled limits4.4Strength reduc

20、tion factor 4.5Stress in steel due to flexure4.6Compression stress limit4.7Moment redistribution4.8Deflection4.9Crack control4.10Minimum reinforcement4.11Strength design for shearChapter 5Columns, p. 145.1Introduction5.2Specified yield strength for longitudinal reinforcement5.3Specified yield streng

21、th for transverse reinforcement5.4Slenderness effectChapter 6Slab systems, p. 156.1One-way slabs6.2Shear design of one-way slabs6.3Two-way slabsS. K. Ghosh Conrad PaulsonAndres Lepage Henry G. RussellKenneth A. Luttrell Joseph C. SandersRobert F. MastThe committee members of ITG-6 would like to than

22、k Wiss, Janey, Elstner Associates, Inc. (WJE) and M. Dawood for their contributions to this document.Paul ZiaChairAdam S. LubellSecretary2 USE OF ASTM A1035/A1035M GRADE 100 (690) STEEL BARS FOR STRUCTURAL CONCRETE (ACI ITG-6R-10)American Concrete Institute Copyrighted Materialwww.concrete.orgChapte

23、r 7Walls, p. 157.1Introduction7.2Vertical reinforcement7.3Horizontal reinforcement7.4Shear reinforcement7.5Minimum reinforcementChapter 8Footings and pile caps, p. 168.1DesignChapter 9Mat foundations, p. 169.1DesignChapter 10Other design considerations, p. 1610.1Seismic design limitations10.2Develop

24、ment and lap splice length10.3Mechanically spliced bars and headed bars10.4Bending and welding of bars10.5Use of ASTM A1035/A1035M bars with ASTMA615/A615M barsChapter 11Summary, p. 18Chapter 12References, p. 1912.1 Referenced standards and reports12.2Cited referencesAppendix ADesign examples, p. 22

25、A.1IntroductionA.2Design examples Appendix BFlexural analysis using nonlinear stress-strain curve of ASTM A1035/A1035M Grade 100 (690) reinforcement, p. 80B.1IntroductionB.2Design assumptionsB.3Spreadsheet implementationB.4Design examplesAppendix CFlexural behavior of beams reinforced with ASTM A103

26、5/A1035M bars, p. 88CHAPTER 1INTRODUCTION1.1ObjectiveThis guide provides design provisions for the use ofASTM A1035/A1035M Grade 100 (690) deformed steelbars for reinforced concrete structural members. This guideaddresses only those requirements in ACI 318-08 that limitthe more efficient use of such

27、 steel bars, and should notaffect the application of other code requirements.1.2ScopeThis guide includes a discussion of the material character-istics of ASTM A1035/A1035M steel bars and recommendsdesign criteria for beams, columns, slab systems, walls, andfootings for Seismic Design Category (SDC)

28、A, B, or C. Fora lack of adequate data, the application of this guide for SDCD, E, or F is limited to slab systems, foundations, and struc-tural components not designated as part of the seismic-force-resisting system but explicitly checked for the inducedeffects of the design displacements. The only

29、 exception isthe use of transverse reinforcement for concrete confinementwith a specified yield strength, fy, up to 100,000 psi (690 MPa)for special moment frames, special structural walls, andcoupling beams as permitted by Section 21.1.5.4 of ACI318-08. Refer to Section 10.1 of this guide for more

30、informa-tion on seismic design considerations. Shells and foldedplate members and prestressed concrete are beyond thescope of this guide. Design examples are included to illus-trate design procedures and proper application of the designcriteria. Modifications to these design criteria may be justi-fi

31、ed where the design adequacy within the scope of thisguide is demonstrated by successful use, analysis, or test.1.3Historical perspective and background For several decades, the design of structural concrete wasrestricted to using specified yield strength, fy, of 60,000 psi(410 MPa) or less for rein

32、forcing bars. Section A603(e) ofACI 318-56 specified that “Stress in tensile and compressivereinforcement at ultimate load shall not be assumed greaterthan the yield point or 60,000 psi, whichever is smaller.” Section 1505 of ACI 318-63, specified two requirements:“(a) When reinforcement is used tha

33、t has a yieldstrength, fy, in excess of 60,000 psi, the yieldstrength to be used in design shall be reduced to0.85fyor 60,000 psi, whichever is greater, unless itis shown by tension tests that at a proof stress equalto the specified yield strength, fy, the strain does notexceed 0.003;(b) Designs sha

34、ll not be based on a yield strength,fy,in excess of 75,000 psi. Design of tension rein-forcement shall not be based on a yield strength, fy,in excess of 60,000 psi unless tests are made incompliance with Section 1508(b).”The Commentary on Section 1505 of ACI 318-63states that “This section provides

35、limitations on theuse of high strength steels to assure safety and satis-factory performance. High strength steelsfrequently have a strain at yield strength or yieldpoint in excess of the 0.003 assumed for theconcrete at ultimate. The requirements of Section1505(a) are to adjust to this condition.Th

36、e maximum stress in tension of 60,000 psi withouttest is to control cracking. The absolute maximum isspecified as 75,000 psi to agree with present ASTMspecifications and as a safeguard until there isadequate experience with the high stresses.”Then the Commentary on Section 1508 of ACI 318-63states t

37、hat “When the design yield point of tension reinforcementexceeds 60,000 psi, detailing for crack controlbecomes even more important. Entirely acceptablestructures have been built, particularly in Sweden,with a design yield strength approaching 100,000 psibut more design criteria for crack control an

38、dconsiderable American practical experience with60,000 psi yield strength tension reinforcement areneeded before higher yield strengths are approvedUSE OF ASTM A1035/A1035M GRADE 100 (690) STEEL BARS FOR STRUCTURAL CONCRETE (ACI ITG-6R-10) 3American Concrete Institute Copyrighted Materialwww.concret

39、e.orgfor general use. The Code, therefore limits tensionreinforcement to 60,000 psi yield strength, unlessspecial full-scale tests are made. It was thought that75,000 psi yield strength tension reinforcementshould be permitted where full-scale testing iseconomically feasible, such as in precast memb

40、ers.The crack width criteria are not too difficult to meetby proper attention to reinforcing details.”The most widely used deformed reinforcing bars conformto ASTM A615/A615M, which include Grade 40 (280),Grade 60 (420), and Grade 75 (520). The Grade 60 (420)reinforcement exhibits minimum yield stre

41、ngth of 60,000 psi(410 MPa) with a distinct yield plateau. ACI 318-08 permitsuse of reinforcing bars with a specified yield strength, fy,exceeding 60,000 psi (410 MPa), but fyis limited to thelesser of 80,000 psi (550 MPa) or the stress corresponding toa strain of 0.0035. Section 11.4.2 of ACI 318-0

42、8 limits thespecified yield strength for deformed bars used as shearreinforcement to 60,000 psi (410 MPa). For deformed barsused as confinement reinforcement (ties or spirals) incompression members, Section 3.5.3.3 of ACI 318-08permits the use of specified yield strength of up to 100,000 psi(690 MPa

43、).When the use of Grade 40 (280) reinforcing bars in the1930s and 1940s was replaced by the use of Grade 60 (420)bars in the 1950s and 1960s, there were concerns aboutfatigue resistance of the higher-strength steel bars. Similarconcerns were expressed in the use of ASTM A1035/A1035Msteel bars. El-Ha

44、cha and Rizkalla (2002) and DeJong et al.(2006) conducted studies on the fatigue behavior of ASTMA1035/A1035M steel bars. Their results indicated that afatigue life of 1 106cycles was observed at a stress rangeof approximately 44,000 psi (310 MPa) for ASTM A1035/A1035M steel bars, as opposed to 23,7

45、00 psi (166 MPa) forGrade 60 (420) reinforcing bars. Thus, ASTM A1035/A1035M steel bars showed comparable fatigue resistance toGrade 60 (420) reinforcing bars because their stress atservice would be higher than that of Grade 60 (420) bars.When compared with ASTM A615/A615M steel, the ASTMA1035/A1035

46、M steel (Grade 100 690 and Grade 120 830)has low carbon content (maximum 0.15%) and high chromiumcontent (8.0 to 10.9%). The carbon and chromium contentsfor ASTM A615/A615M steel are typically 0.30% and0.50%, respectively, as reported by Trejo (2002). Being lowin carbon and high in chromium, the AST

47、M A1035/A1035Msteel is more corrosion-resistant and has higher tensile strengththan conventional reinforcement (Rizkalla et al. 2005).Figure 1.1 shows the comparison of typical stress-straincurves for ASTM A615/A615M, ASTM A706/A706M, andASTM A1035/A1035M reinforcing bars (WJE 2008). TheASTM A1035/A

48、1035M bar (Grade 100 690 or Grade 120830) exhibits a linear stress-strain relationship up to aproportional limit ranging from 60,000 psi (410 MPa) to80,000 psi (550 MPa), without a well-defined yield plateau.(Refer to Appendix C for a discussion on how the lack of awell-defined yield plateau affects

49、 the flexural behavior ofbeams.) Actual yield strength, determined by the 0.2% offsetmethod, typically exceeds 115,000 psi (790 MPa) for Grade100 (690) and 125,000 psi (860 MPa) for Grade 120 (830)bars. The tensile strength typically exceeds 155,000 psi (1070MPa) for Grade 100 (690) bars and 160,000 psi (1100 MPa)for Grade 120 (830) bars. The corresponding strain at thepeak of the stress-strain curve ranges from 0.04 to 0.06.Refer to Chapter 3 for more details on the material character-istics of ASTM A1035/A10