1、ACI 341.3R-07Seismic Evaluation and RetrofitTechniques for Concrete BridgesReported by ACI Committee 341American Concrete InstituteAdvancing concrete knowledgeSeismic Evaluation and Retrofit Techniquesfor Concrete BridgesFirst PrintingMarch 2007ISBN 978-0-87031-236-6Copyright by the American Concret
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9、n: ACI documents are available in print, 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 Institute388
10、00 Country Club DriveFarmington Hills, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-848-3701www.concrete.orgACI 341.3R-07 was adopted and published March 2007.Copyright 2007, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including t
11、he making of copies 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.341.3R-1ACI Commit
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14、tdocuments. 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.Seismic Evaluation and Retrofit Techniquesfor Concrete BridgesReported by ACI Committee 341A
15、CI 341.3R-07This document provides a summary of seismic evaluation and retrofittechniques for reinforced concrete bridges. The document is intended to beuseful to practicing engineers and academic researchers. Three primaryphases of a retrofit program are described: seismic vulnerability evaluation,
16、evaluation of the seismic demands and capacities, and selection and designof the retrofit measures. General descriptions of appropriate linear andnonlinear analysis methods to evaluate the seismic response of an existingbridge are provided. Various retrofit measures for individual bridgecomponents a
17、re described. In all cases, the information is presented at theconceptual level rather than providing detailed descriptions of the designmethod. A rich resource of references is included in each section of thedocument for obtaining more specific information on the subject matter.Keywords: abutment;
18、bridges; column; expansion joint; footing; hinge;joint; pier; pile; seismic analysis; seismic evaluation; seismic isolation;seismic retrofit.CONTENTSChapter 1Introduction, p. 341.3R-21.1Seismic vulnerability evaluation1.2Seismic demand-capacity evaluation1.3Seismic retrofit measures1.4Implementation
19、Chapter 2Seismic vulnerability evaluation,p. 341.3R-42.1Structural vulnerability indicators2.2Vulnerable structural elementsChapter 3Seismic evaluation, p. 341.3R-103.1Seismic demand evaluation3.2Seismic capacity evaluation3.3Evaluation of demand-capacity ratiosChapter 4Seismic retrofit measures,p.
20、341.3R-144.1Columns4.2Cap beams4.3Cap beam-column joints4.4FootingsHossam M. Abdou Angel E. Herrera Bradley N. Robson Naresh ShahNagi A. Abo-Shadi Eric Michael Hines Mario E. Rodriguez Khaled S. SoubraMark A. Aschheim Kosalram Krishnan M. Saiid Saiidi Bozidar StojadinovicOguzhan Bayrak Dawn E. Lehma
21、n*Ayman E. Salama Stewart C. WatsonSarah L. Billington Stavroula J. Pantazopoulou David H. Sanders*Nadim I. WehbeJoAnn P. Browning Anthony C. Powers*Guillermo Santana Eric B. Williamson*W. Gene CorleyAdolfo Matamoros, associate member of the main committee and subcommittee member, also contributed s
22、ubstantially to this document. His effort is gratefully acknowledged.*Member of subcommittee that prepared this report.Co-Chair of subcommittee that prepared this report.Raj Valluvan*ChairSri Sritharan*Secretary341.3R-2 ACI COMMITTEE REPORT4.5Hinges and supports4.6Superstructures4.7Abutments4.8Dynam
23、ic isolation and mechanical devices4.9General retrofit considerationsChapter 5Conclusions, p. 341.3R-24Chapter 6References, p. 341.3R-246.1Referenced standards and reports6.2Cited referencesCHAPTER 1INTRODUCTIONPerformance of bridges in past earthquakes indicates thatexisting bridge structures can b
24、e susceptible to severestructural damage. This vulnerability is evident in regions ofhigh seismic risk, as demonstrated by extensive damage inbridge structures in the 1971 San Fernando Earthquake(Fung et al. 1971), the 1989 Loma Prieta Earthquake (EERI1989) and the 1994 Northridge Earthquake (Moehle
25、 1995).In those earthquakes, damage included pounding at expansionjoints, severe spalling and cracking in bridge columns andjoints, and structural collapse. The 2001 Nisqually Earthquakein the state of Washington resulted in damage to columns,restrainers, and the superstructure due to pounding, indi
26、-cating that some bridges in the United States may besusceptible to damage even in moderate earthquakes (Ranfand Eberhard 2002).The bridge damage resulting from the San Fernando earth-quake caused concern about the seismic vulnerability ofbridges and initiated research into and development ofseismic
27、 retrofit guidelines and measures (Applied TechnologyCouncil (ATC) 1983; Zelinski 1985; Buckle et al. 1986;Selna et al. 1989a,b). These earlier guidelines and proceduresfor seismic retrofit of bridges used strength-based evaluationapproaches in which the forces were used as a basis for theevaluation
28、. If the seismic force demand exceeds the elasticstrength of the structure, the structural system may besubjected to large inelastic displacements and subsequentstrength degradation, instability, or both, of the system thatcould lead to structural collapse. In this case, retrofitmeasures solely base
29、d on a strength-based approach may notprovide adequate deformation capacity to ensure structuralstability. Damage to bridges in the Loma Prieta andNorthridge earthquakes emphasized the need to address bothstrength and deformation capacities in bridge seismic retrofitprograms, which has resulted in m
30、ore comprehensiveseismic retrofit prioritization schemes as well as improvedevaluation procedures and retrofit measures.A comprehensive retrofit measure for a concrete bridgerequires detailed evaluation of the probable strength andstiffness characteristics at member and structure levels,structural d
31、isplacement and component deformation capacities,and earthquake hazard potential. As such, deformation-based retrofit approaches may be more appropriate to ensuresurvival of the structure without experiencing collapse underextreme earthquakes. Alternatively, energy-based approachesmay be adopted as
32、long as these approaches sufficientlyaddress all required elements of the complete retrofit plan.Seismic retrofit guidelines started to include these approachesin the early 1990s (Maroney 1990; Lwin and Henley 1993).Retrofit measures have traditionally been developed toimprove seismic performance in
33、 extreme events where theprimary concern was ensuring structural stability to preventcollapse. More recently, engineers have focused ondesigning to reduce damage in more frequent events(Lehman et al. 2004; MCEER-ATC 2003). The pairing of acapacity or performance level with a seismic hazard level isc
34、alled a performance objective. Engineering a structure usingmultiple performance objectives is termed performance-based earthquake engineering. For example, in addition toensuring structural stability at the maximum consideredearthquake, the performance of the structure at the operationallimit state
35、s (that is, no damage needing repair) and delayedoperational limit states (that is, permitting repairable damage)may also be considered to ensure satisfactory structuralperformance under the appropriate seismic hazard levels (forexample, frequent and moderate earthquakes, respectively).Using a perfo
36、rmance-based approach may be advantageousfor the retrofit of existing structures in that a designer, foreconomical reasons, may choose to upgrade the structure toa performance level that is less than that implied by thecurrent code. Performance-based engineering procedures areunder development, and
37、the performance of available retrofitstrategies under different multiple hazard levels has yet to beevaluated and, therefore, is not directly addressed herein.This document presents a summary of seismic evaluationand retrofit techniques suitable for ensuring structuralstability. A comprehensive seis
38、mic retrofit program consistingof multiple retrofit stages will permit efficient and cost-effective retrofit solutions where each stage consists ofbridges that will meet a state-specific prioritization criteria(Lwin and Henley 1993). As illustrated in Fig. 1.1, the primaryphases of a seismic bridge
39、retrofit program should include:1. Seismic vulnerability evaluation;2. Seismic demand-capacity evaluation;3. Selection of efficient retrofit measures and their design;and4. Implementation.This document briefly describes the phases of a seismicretrofit program followed by sections that provide a more
40、thorough treatment of key aspects of the first three phases.The vulnerability evaluation, demand-capacity evaluation,and retrofit measures presented are described for monolithicreinforced concrete bridges, but may be applicable to otherbridge types. In the subsequent sections, emphasis is placedon p
41、roviding a general understanding of the developmentand execution of each phase, with a focus on achievingstructural stability performance. Seismic retrofit measuresare presented at a conceptual level for the critical membersresponsible for ensuring ductile seismic response. Designand analysis method
42、s vary within the research and designcommunities, and therefore specifics of each method are notprovided in this document. A rich resource of appropriatereferences, however, is given in each section. For morespecific and detailed retrofit design and analysis information,SEISMIC EVALUATION AND RETROF
43、IT TECHNIQUES FOR CONCRETE BRIDGES 341.3R-3the reader is referred to the recommended references.Information regarding the definition of common terms usedto describe seismic retrofit of bridges may be found inYashinsky and Karshenas (2003).1.1Seismic vulnerability evaluationThe first phase of a seism
44、ic retrofit program consists ofidentifying vulnerable bridges and developing a prioritizationscheme that accounts for their vulnerability and impact ofbridge closure. In this phase, an approximate, rather than adetailed and accurate, vulnerability assessment is carried outfor each bridge or bridge t
45、ype. Issues that should be givenconsideration in the seismic vulnerability evaluation phase,as indicated in Fig. 1.1, are: 1. Evaluation of the site-specific seismic hazards includingthe influence of the local soil and the likelihood of lateralspreading, settlement, and liquefaction;2. Evaluation of
46、 the structural vulnerability including theeffects of physical geometry, date of design and construction,structural detailing, the actual physical condition, and thefoundation soil conditions. Information regarding theperformance of comparable laboratory specimens or bridgesin previous earthquakes s
47、hould be considered; and3. Evaluation of the socioeconomic consequences ofdamage or failure including issues related to potentialcasualties, rescue and recovery operations, lifeline interruption,detours, and economic impact in case of temporary closureor failure.The aforementioned information requir
48、ed should beaggregated to develop a retrofit prioritization scheme forbridges in a seismic region. General aspects of seismicretrofit prioritization schemes have been studied (Basoz andKiremidjian 1997); however, they may differ from state tostate. The California Department of Transportation basedth
49、eir prioritization scheme on outcomes from a workshopsponsored by the Applied Technology Council (ATC 1983)and implemented several seismic retrofit proceduresfollowing the Loma Prieta Earthquake (Roberts 1990b,1993). Other western states, including Nevada, Washington(Lwin and Henley 1993), and Oregon (ODOT 1999) alsomaintain active bridge seismic retrofit programs. Nationwide,many other states, including Kentucky, Missouri, Illinois,Indiana, and New York, have programs at various stages ofdevelopment. For example, the Kentucky TransportationCabinet, through re
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