ACI ITG-5.1M-2007 Acceptance Criteria for Special Unbonded Post-Tensioned Precast Structural Walls Based on Validation Testing and Commentary.pdf

1、ACI ITG-5.1M-07Acceptance Criteria for SpecialUnbonded Post-TensionedPrecast Structural Walls Based onValidation Testing and CommentaryReported by ACI Innovation Task Group 5An ACI StandardAmerican Concrete InstituteAdvancing concrete knowledgeAcceptance Criteria for Special Unbonded Post-Tensioned

2、Precast Structural WallsBased on Validation Testing and CommentaryISBN 978-0-87031-301-1Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This materialmay not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or otherdistr

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5、r the most up-to-date revisions.ACI committee documents are intended for the use of individuals who are competent to evaluate thesignificance and limitations of its content and recommendations and who will accept responsibility for theapplication of the material it contains. Individuals who use this

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10、nt, by download, on CD-ROM, through electronicsubscription, 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

11、, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-848-3701www.concrete.orgACI ITG-5.1M-07 was adopted October 24, 2007 and published March 2008.Copyright 2008, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copie

12、s by any photo process, or by electronic ormechanical device, printed, written, or oral, or recording for sound or visual reproductionor for use in any knowledge or retrieval system or device, unless permission in writingis obtained from the copyright proprietors.ITG-5.1M-1ACI Committee Reports, Gui

13、des, Manuals, StandardPractices, and Commentaries are intended for guidance inplanning, designing, executing, and inspecting construction.This document is intended for the use of individuals who arecompetent to evaluate the significance and limitations of itscontent and recommendations and who will

14、acceptresponsibility for the application of the material it contains.The American Concrete Institute disclaims any and allresponsibility for the stated principles. The Institute shall notbe liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocume

15、nts. If items found in this document are desired by theArchitect/Engineer to be a part of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.Acceptance Criteria for Special UnbondedPost-Tensioned Precast Structural WallsBased on Validation

16、Testing and CommentaryAn ACI StandardReported by ACI Innovation Task Group 5ACI ITG-5.1M-07This document applies to structures in regions of high seismic risk or tostructures assigned to high seismic performance or design categories. Itdefines the minimum experimental evidence that can be deemed to

17、satisfythe use of unbonded post-tensioned precast structural walls (shear walls)for bearing wall and building frame special reinforced concrete shear wallsystems, as defined in ASCE/SEI 7-05, when those walls do not fully satisfythe intent of the prescriptive requirements of Chapter 21 of ACI 318M-0

18、5.This document includes mandatory Acceptance Criteria and nonmandatoryCommentary, and has been written in such a form that its requirements canbe coordinated directly with the requirements for special precast structuralwalls in 21.8 of ACI 318M-05. Among the subjects covered are requirementsfor the

19、 procedures that shall be used to design unbonded post-tensionedprecast test modules and their configurations, as well as requirements fortesting, reporting, and assessing satisfactory performance of the test modules.The references of the Commentary provide documentary evidence,additional to the ref

20、erences of Chapter 21 of ACI 318RM-05, that supportthe acceptance criteria. Consistent with the approach of ACI 318M, nocomparison is made, either in the body of the Acceptance Criteria orCommentary, of research results for precast test modules satisfying ACI318M with those for modules that, althoug

21、h not satisfying ACI 318M, dosatisfy the Acceptance Criteria. Such comparisons, both experimental andanalytical, are available in the Commentary references.In this document, consistent with the format of ACI 318M-05, the word“Section” is not included before a reference to a section of ACI 318M-05.To

22、 more clearly designate a section in this document, however, the word“Section” is used before any reference to a section of this document.The section numbering for the Commentary is the same as that for theStandard, with numbers preceded by an “R” and the text in italics to distin-guish them from th

23、e corresponding section numbers of the Standard.Keywords: acceptance criteria; coupling element; drift; drift angle;energy dissipation; lateral resistance; post-tensioning; precast concrete;prestressed concrete; seismic design; shear wall; structural wall; testmodule; toughness.CONTENTSChapter 1Intr

24、oduction and scope, p. ITG-5.1M-2Chapter 2Notation and definitions, p. ITG-5.1M-5Chapter 3Design procedure, p. ITG-5.1M-8Chapter 4Test modules, p. ITG-5.1M-9Chapter 5Test method, p. ITG-5.1M-12Chapter 6Test report, p. ITG-5.1M-15Chapter 7Test module acceptance criteria,p. ITG-5.1M-16Chapter 8Referen

25、ced standards, p. ITG-5.1M-18Attila B. Beres Vilas S. Mujumdar Carol K. ShieldNed M. Cleland Suzanne Dow Nakaki John W. WallaceNeil M. Hawkins Stephen P. Pessiki Loring A. Wyllie, Jr.Ronald KlemencicConsulting memberS. K. GhoshCharles W. DolanChairITG-5.1M-2 ACI STANDARDCHAPTER 1INTRODUCTION AND SCO

26、PE1.1IntroductionFor seismic design, 21.2.1.5 of ACI 318M specifies that “areinforced concrete structural system not satisfying therequirements of this chapter (Chapter 21) shall be permittedif it is demonstrated by experimental evidence and analysisthat the proposed system has strength and toughnes

27、s equal toor exceeding those provided by a comparable monolithicreinforced concrete structure satisfying this chapter.” Thisdocument defines the minimum experimental evidencerequired to validate the use of special unbonded post-tensioned precast structural wall systems in regions of highseismic risk

28、 or for structures assigned to high seismicperformance or design categories when those systems do notsatisfy fully the prescriptive requirements of Chapter 21 ofACI 318M. The provisions of this document are intended tosupplement the provisions of Chapter 21 of ACI 318M andnot to supplant them.Consis

29、tent with the 21.2.1.5 requirement of ACI 318M, thisdocument specifies that, before the validation testing mandatedby the document is undertaken, a design procedure shall havebeen developed for prototype unbonded post-tensioned precaststructural walls having the generic form for which acceptanceis s

30、ought. Further, the same design procedure shall be used toproportion the test modules. The document also requires thatthe prototype buildings that contain the unbonded post-tensioned precast structural walls have proportions that areessentially regular in the vertical direction, having nosignificant

31、 physical discontinuities in plan, in verticalconfiguration, or in their lateral-force-resisting systems.This document is intended for walls that might, forexample, involve the use of precast elements, precast/prestressed elements, post-tensioned reinforcement or combi-nations of those elements and

32、reinforcement. Comprehensiveprescriptive requirements for unbonded post-tensionedprecast structural walls constructed with such elements arenot included in ACI 318M.1.2Scope and general requirementsR1.2Scope and general requirementsWhile only ACI Committee 318 can specify the requirementsnecessary f

33、or unbonded post-tensioned precast walls to meetthe provisions of 21.2.1.5 of ACI 318M, 1.4 of ACI 318Mpermits the building official to accept precast wall systems,other than those explicitly covered by Chapter 21 of ACI318M, provided specific tests, load factors, deflection limits,construction proc

34、edures, and other pertinent requirementshave been established for acceptance of such systemsconsistent with the intent of the Code. This documentprovides a framework that establishes the specific tests, loadfactors, deflection limits, and other pertinent requirementsappropriate for acceptance for re

35、gions of high seismic riskor for structures assigned to high seismic performance ordesign categories of unbonded post-tensioned precast wallsystems, including unbonded post-tensioned precast coupledwall systems, not satisfying all the prescriptive requirementsof Chapter 21 of ACI 318M.This document

36、assumes that the unbonded post-tensionedprecast wall system to be tested has details that differ fromthose prescribed by 21.7 of ACI 318M for conventionalmonolithic reinforced concrete construction. Such wallsmay, for example, involve the use of precast elements,precast prestressed elements, post-te

37、nsioned reinforcement,or combinations of those elements and reinforcement. Lifesafety and toughness are theoretically enhanced by mildsteel reinforcement grouted across the wall to foundationinterface. The presence of mild steel reinforcement,however, makes erection more difficult, and may inhibit t

38、heself-centering action provided by unbonded post-tensioningcrossing the same interface. For an uncoupled wall, mildsteel reinforcement, or some other form of energy-dissipatingbase connection, is necessary to meet the relative energydissipation requirements of this document. For coupledwalls, howev

39、er, energy-dissipating coupling elements can beused along the vertical boundaries between walls so thatonly unbonded post-tensioning tendons need to cross thewall to foundation interface. Life safety for coupled walls isthen more critically dependent on the unbonded post-tensioning not fracturing un

40、der the seismic event. In thatcase, careful attention should be paid to corrosion protection ofthe tendon and to stress increases in the tendon during theseismic event.For monolithic reinforced concrete walls, a fundamentaldesign concept underlying the Chapter 21 provisions of ACI318M is that walls

41、with hw/lw exceeding 1.0 should beproportioned so that their inelastic response is dominated byflexural action on a critical section located near the base ofthe wall. That same basic fundamental concept is retained inthis document. The limiting hw/lwvalue, however, is reducedto 0.5. The basis for th

42、at lower limit is discussed in R1.2.2.Tests on modules, as envisioned in this document, cannotbe extrapolated with confidence to the performance ofpanelized walls of proportions differing from those tested forthe development of Chapter 21 of ACI 318M if the shear-slipdisplacement pattern or excessiv

43、e joint opening pattern ofFig. R2.3 is significant in the response developed in the teston the module.Two other fundamental requirements of Chapter 21 of ACI318M are for closely spaced ties around heavily strainedboundary element reinforcement and the provision ofminimum amounts of uniformly distrib

44、uted horizontal andvertical reinforcement in the web of the wall. Ties aroundboundary element reinforcement to inhibit its buckling incompression are required where the strain in the extremecompression fiber exceeds 0.003 and spalling of the coverconcrete may occur. Those ties then provide confineme

45、ntthat maintains the integrity of the boundary element andpermits the confined concrete to develop increasingcompressive forces with increasing lateral displacements inspite of the loss of the concrete cover. Minimum amounts ofuniformly distributed horizontal and vertical reinforcementover the heigh

46、t and length of the wall are required to restrainthe opening of inclined cracks and allow the development ofSPECIAL UNBONDED POST-TENSIONED PRECAST STRUCTURAL WALLS ITG-5.1M-3the minimum acceptable drift angle capacities specified inSection 5.4. Deviations from those tie and distributedreinforcement

47、 requirements are possible only if a theory isdeveloped that can substantiate reasons for such deviationsand that theory is tested as part of the validation testing.1.2.1 This document defines minimum acceptance criteriafor unbonded post-tensioned precast structural walls,including coupled unbonded

48、post-tensioned precast structuralwalls, designed for regions of high seismic risk or for structuresassigned to high seismic performance or design categories,where acceptance is based on experimental evidence andanalysis.R1.2.1 This document is not intended for use directly withexisting construction

49、or for use with walls that are designedto conform to all the requirements of 21.7 of ACI 318M. Thecriteria of this document are at least as stringent as those forwalls designed to the minimum requirements of 21.7 of ACI318M. Some walls designed to 21.7, and having low height-length ratios, may not meet the minimum acceptable driftangle capacity of Eq. (5-1) because their behavior may begoverned almost entirely by shear deformations (Hidalgo etal. 2002). The height-length ratio of 0.5 is the least value forwhich Eq. (5-1) is applicable.1.2.2 This document is applicable to unbonde