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1、ACI ITG-5.1-07 Acceptance Criteria for Special Unbonded Post-Tensioned Precast Structural Walls Based on Validation Testing and Commentary Reported by ACI Innovation Task Group 5 An ACI Standard American Concrete Institute Advancing concrete knowledge Acceptance Criteria for Special Unbonded Post-Te
2、nsioned Precast Structural Walls Based on Validation Testing and Commentary First printing March 2008 ISBN 978-0-87031-270-0 Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mecha
3、nical, electronic, film, or other distribution and storage media, without the written consent of ACI. The technical committees responsible for ACI committee reports and standards strive to avoid ambiguities, omissions, and errors in these documents. In spite of these efforts, the users of ACI docume
4、nts occasionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions for the improvement of ACI documents are requested to contact ACI. Proper use of this document includes periodically checking for errata
5、 at www.concrete.org/committees/errata.asp for the most up-to-date revisions. ACI committee documents are intended for the 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 th
6、e material it contains. Individuals who use this publication in any way assume all risk and accept total responsibility for the application and use of this information. All information in this publication is provided “as is” without warranty of any kind, either express or implied, including but not
7、limited to, the implied warranties of merchantability, fitness for a particular purpose or non-infringement. ACI and its members disclaim liability for damages of any kind, including any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost prof
8、its, which may result from the use of this publication. It is the responsibility of the user of this document to establish health and safety practices appropriate to the specific circumstances involved with its use. ACI does not make any representations with regard to health and safety issues and th
9、e use of this document. The user must determine the applicability of all regulatory limitations before applying the document and must comply with all applicable laws and regulations, including but not limited to, United States Occupational Safety and Health Administration (OSHA) health and safety st
10、andards. Order information: ACI documents are available in print, by download, on CD-ROM, through electronic subscription, or reprint and may be obtained by contacting ACI. Most ACI standards and committee reports are gathered together in the annually revised ACI Manual of Concrete Practice (MCP). A
11、merican Concrete Institute 38800 Country Club Drive Farmington Hills, MI 48331 U.S.A. Phone:248-848-3700 Fax:248-848-3701 www.concrete.org ACI ITG-5.1-07 was adopted October 24, 2007 and published March 2008. Copyright 2008, American Concrete Institute. All rights reserved including rights of reprod
12、uction 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
13、obtained from the copyright proprietors. ITG-5.1-1 ACI Committee Reports, Guides, Manuals, Standard Practices, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate
14、 the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or d
15、amage arising therefrom. Reference to this document shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. Accepta
16、nce Criteria for Special Unbonded Post-Tensioned Precast Structural Walls Based on Validation Testing and Commentary An ACI Standard Reported by ACI Innovation Task Group 5 ACI ITG-5.1-07 This document applies to structures in regions of high seismic risk or to structures assigned to high seismic pe
17、rformance or design categories. It defines the minimum experimental evidence that can be deemed to satisfy the use of unbonded post-tensioned precast structural walls (shear walls) for bearing wall and building frame special reinforced concrete shear wall systems, as defined in ASCE/SEI 7-05, when t
18、hose walls do not fully satisfy the intent of the prescriptive requirements of Chapter 21 of ACI 318-05. This document includes mandatory Acceptance Criteria and nonmandatory Commentary, and has been written in such a form that its requirements can be coordinated directly with the requirements for s
19、pecial precast structural walls in 21.8 of ACI 318-05. Among the subjects covered are requirements for the procedures that shall be used to design unbonded post-tensioned precast test modules and their configurations, as well as requirements for testing, reporting, and assessing satisfactory perform
20、ance of the test modules. The references of the Commentary provide documentary evidence, additional to the references of Chapter 21 of ACI 318R-05, that support the acceptance criteria. Consistent with the approach of ACI 318, no comparison is made, either in the body of the Acceptance Criteria or C
21、ommentary, of research results for precast test modules satisfying ACI 318 with those for modules that, although not satisfying ACI 318, do satisfy the Acceptance Criteria. Such comparisons, both experimental and analytical, are available in the Commentary references. In this document, consistent wi
22、th the format of ACI 318-05, the word “Section” is not included before a reference to a section of ACI 318-05. To 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
23、 same as that for the Standard, with numbers preceded by an “R” and the text in italics to distin- guish them from the corresponding section numbers of the Standard. Keywords: acceptance criteria; coupling element; drift; drift angle; energy dissipation; lateral resistance; post-tensioning; precast
24、concrete; prestressed concrete; seismic design; shear wall; structural wall; test module; toughness. CONTENTS Chapter 1Introduction and scope, p. ITG-5.1-2 Chapter 2Notation and definitions, p. ITG-5.1-5 Chapter 3Design procedure, p. ITG-5.1-8 Chapter 4Test modules, p. ITG-5.1-9 Chapter 5Test method
25、, p. ITG-5.1-12 Chapter 6Test report, p. ITG-5.1-15 Chapter 7Test module acceptance criteria, p. ITG-5.1-16 Chapter 8Referenced standards, p. ITG-5.1-18 Attila B. BeresVilas S. MujumdarCarol K. Shield Ned M. ClelandSuzanne Dow NakakiJohn W. Wallace Neil M. HawkinsStephen P. PessikiLoring A. Wyllie,
26、Jr. Ronald Klemencic Consulting member S. K. Ghosh Charles W. Dolan Chair ITG-5.1-2ACI STANDARD CHAPTER 1INTRODUCTION AND SCOPE 1.1Introduction For seismic design, 21.2.1.5 of ACI 318 specifies that “a reinforced concrete structural system not satisfying the requirements of this chapter (Chapter 21)
27、 shall be permitted if it is demonstrated by experimental evidence and analysis that the proposed system has strength and toughness equal to or exceeding those provided by a comparable monolithic reinforced concrete structure satisfying this chapter.” This document defines the minimum experimental e
28、vidence required to validate the use of special unbonded post- tensioned precast structural wall systems in regions of high seismic risk or for structures assigned to high seismic performance or design categories when those systems do not satisfy fully the prescriptive requirements of Chapter 21 of
29、ACI 318. The provisions of this document are intended to supplement the provisions of Chapter 21 of ACI 318 and not to supplant them. Consistent with the 21.2.1.5 requirement of ACI 318, this document specifies that, before the validation testing mandated by the document is undertaken, a design proc
30、edure shall have been developed for prototype unbonded post- tensioned precast structural walls having the generic form for which acceptance is sought. Further, the same design procedure shall be used to proportion the test modules. The document also requires that the prototype buildings that contai
31、n the unbonded post-tensioned precast structural walls have proportions that are essentially regular in the vertical direction, having no significant physical discontinuities in plan, in vertical configuration, or in their lateral-force-resisting systems. This document is intended for walls that mig
32、ht, for example, involve the use of precast elements, precast/ prestressed elements, post-tensioned reinforcement or combi- nations of those elements and reinforcement. Comprehensive prescriptive requirements for unbonded post-tensioned precast structural walls constructed with such elements are not
33、 included in ACI 318. 1.2Scope and general requirements R1.2Scope and general requirements While only ACI Committee 318 can specify the requirements necessary for unbonded post-tensioned precast walls to meet the provisions of 21.2.1.5 of ACI 318, 1.4 of ACI 318 permits the building official to acce
34、pt precast wall systems, other than those explicitly covered by Chapter 21 of ACI 318, provided specific tests, load factors, deflection limits, construction procedures, and other pertinent requirements have been established for acceptance of such systems consistent with the intent of the Code. This
35、 document provides a framework that establishes the specific tests, load factors, deflection limits, and other pertinent requirements appropriate for acceptance for regions of high seismic risk or for structures assigned to high seismic performance or design categories of unbonded post-tensioned pre
36、cast wall systems, including unbonded post-tensioned precast coupled wall systems, not satisfying all the prescriptive requirements of Chapter 21 of ACI 318. This document assumes that the unbonded post-tensioned precast wall system to be tested has details that differ from those prescribed by 21.7
37、of ACI 318 for conventional monolithic reinforced concrete construction. Such walls may, for example, involve the use of precast elements, precast prestressed elements, post-tensioned reinforcement, or combinations of those elements and reinforcement. Life safety and toughness are theoretically enha
38、nced by mild steel reinforcement grouted across the wall to foundation interface. The presence of mild steel reinforcement, however, makes erection more difficult, and may inhibit the self-centering action provided by unbonded post-tensioning crossing the same interface. For an uncoupled wall, mild
39、steel reinforcement, or some other form of energy-dissipating base connection, is necessary to meet the relative energy dissipation requirements of this document. For coupled walls, however, energy-dissipating coupling elements can be used along the vertical boundaries between walls so that only unb
40、onded post-tensioning tendons need to cross the wall to foundation interface. Life safety for coupled walls is then more critically dependent on the unbonded post- tensioning not fracturing under the seismic event. In that case, careful attention should be paid to corrosion protection of the tendon
41、and to stress increases in the tendon during the seismic event. For monolithic reinforced concrete walls, a fundamental design concept underlying the Chapter 21 provisions of ACI 318 is that walls with hw/lw exceeding 1.0 should be proportioned so that their inelastic response is dominated by flexur
42、al action on a critical section located near the base of the wall. That same basic fundamental concept is retained in this document. The limiting hw/lw value, however, is reduced to 0.5. The basis for that lower limit is discussed in R1.2.2. Tests on modules, as envisioned in this document, cannot b
43、e extrapolated with confidence to the performance of panelized walls of proportions differing from those tested for the development of Chapter 21 of ACI 318 if the shear-slip displacement pattern or excessive joint opening pattern of Fig. R2.3 is significant in the response developed in the test on
44、the module. Two other fundamental requirements of Chapter 21 of ACI 318 are for closely spaced ties around heavily strained boundary element reinforcement and the provision of minimum amounts of uniformly distributed horizontal and vertical reinforcement in the web of the wall. Ties around boundary
45、element reinforcement to inhibit its buckling in compression are required where the strain in the extreme compression fiber exceeds 0.003 and spalling of the cover concrete may occur. Those ties then provide confinement that maintains the integrity of the boundary element and permits the confined co
46、ncrete to develop increasing compressive forces with increasing lateral displacements in spite of the loss of the concrete cover. Minimum amounts of uniformly distributed horizontal and vertical reinforcement over the height and length of the wall are required to restrain the opening of inclined cra
47、cks and allow the development of SPECIAL UNBONDED POST-TENSIONED PRECAST STRUCTURAL WALLSITG-5.1-3 the minimum acceptable drift angle capacities specified in Section 5.4. Deviations from those tie and distributed reinforcement requirements are possible only if a theory is developed that can substant
48、iate reasons for such deviations and that theory is tested as part of the validation testing. 1.2.1 This document defines minimum acceptance criteria for unbonded post-tensioned precast structural walls, including coupled unbonded post-tensioned precast structural walls, designed for regions of high
49、 seismic risk or for structures assigned to high seismic performance or design categories, where acceptance is based on experimental evidence and analysis. R1.2.1 This document is not intended for use directly with existing construction or for use with walls that are designed to conform to all the requirements of 21.7 of ACI 318. The criteria of this document are at least as stringent as those for walls designed to the minimum requirements of 21.7 of ACI 318. Some walls designed to 21.7, and having low height- length ratios, may not meet the minimum acceptable drift angle capac
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