ACI 437R-2003 Strength Evaluation of Existing Concrete Buildings《现有混凝土建筑的强度评估》.pdf

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1、ACI 437R-03 supersedes ACI 437R-91(Reapproved 1997) and became effectiveAugust 14, 2003.Copyright 2003, 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 ormechani

2、cal 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.437R-1ACI Committee Reports, Guides, Standard Practices, andCommentaries are intended

3、for guidance in planning,designing, executing, and inspecting construction. Thisdocument is intended for the use of individuals who arecompetent to evaluate the significance and limitations of itscontent and recommendations and who will acceptresponsibility for the application of the material it con

4、tains.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 contractdocuments. If items found in this document are desired by theArchitec

5、t/Engineer to be a part of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.It is the responsibility of the user of this document toestablish health and safety practices appropriate to the specificcircumstances involved with its use. ACI

6、does not make anyrepresentations with regard to health and safety issues and theuse of this document. The user must determine the applicabilityof all regulatory limitations before applying the document andmust comply with all applicable laws and regulations,including but not limited to, United State

7、s Occupational Safetyand Health Administration (OSHA) health and safetystandards.Strength Evaluation of Existing Concrete BuildingsACI 437R-03The strength of existing concrete buildings and structures can be evaluatedanalytically or in conjunction with a load test. The recommendations inthis report

8、indicate when such an evaluation may be needed, establishcriteria for selecting the evaluation method, and indicate the data andbackground information necessary for an evaluation. Methods of determiningmaterial properties used in the analytical and load tests investigation aredescribed in detail. An

9、alytical investigations should follow the principles ofstrength design outlined in ACI 318. Working stress analysis can supplementthe analytical investigations by relating the actual state of stress in struc-tural components to the observed conditions. Procedures for conductingstatic load tests and

10、criteria indicated for deflection under load andrecovery are recommended.Keywords: cracking; deflection; deformation; deterioration; gravity load;load; load test; reinforced concrete; strength; strength evaluation; test.CONTENTSChapter 1Introduction, p. 437R-21.1Scope1.2Applications1.3Exceptions1.4C

11、ategories of evaluation1.5Procedure for a structural evaluation1.6Commentary1.7Organization of the reportChapter 2Preliminary investigation, p. 437R-32.1Review of existing information2.2Condition survey of the buildingChapter 3Methods for material evaluation,p. 437R-93.1Concrete3.2Reinforcing steelC

12、hapter 4Assessment of loading conditions and selection of evaluation method, p. 437R-144.1Assessment of loading and environmental conditions4.2Selecting the proper method of evaluationReported by ACI Committee 437Tarek Alkhrdaji* Azer Kehnemui Stephen PessikiJoseph A. Amon Andrew T. Krauklis Predrag

13、 L. PopovicNicholas J. Carino* Michael W. Lee* Guillermo Ramirez*Mary H. Darr Daniel J. McCarthy Andrew ScanlonMark William Fantozzi Patrick R. McCormick K. Nam ShiuPaul E. Gaudette Matthew A. Mettemeyer Avanti C. ShroffZareh B. Gregorian Thomas E. Nehil Jay ThomasPawan R. Gupta Renato Parretti* Hab

14、ib M. Zein Al-AbideenAshok M. Kakade Brian J. Pashina Paul H. Ziehl*Dov KaminetzkyAntonio Nanni*ChairJeffrey S. West*Secretary*Members of the committee who prepared this report.437R-2 ACI COMMITTEE REPORTChapter 5Evaluation, p. 437R-165.1Analytical evaluation5.2Supplementing the analytical evaluatio

15、n with load tests5.3Research needsChapter 6References, p. 437R-226.1Referenced standards and reports6.2Cited references6.3Other referencesAppendix ACyclic load test method, p. 437R-25Appendix BReports from other organizations,p. 437R-28CHAPTER 1INTRODUCTION1.1ScopeThis report provides recommendation

16、s to establish theloads that can be sustained safely by the structural elementsof an existing concrete building. The procedures can beapplied generally to other concrete structures, provided thatappropriate evaluation criteria are agreed upon before thestart of the investigation. This report covers

17、structuralconcrete, including conventionally reinforced cast-in-placeconcrete, precast-prestressed concrete, and post-tensionedcast-in-place (concrete).1.2ApplicationsThe procedures recommended in this report apply wherestrength evaluation of an existing concrete building isrequired in the following

18、 circumstances: Structures that show damage from excess or improperloading, explosions, vibrations, fire, or other causes; Structures where there is evidence of deterioration orstructural weakness, such as excessive cracking or spallingof the concrete, reinforcing bar corrosion, excessivemember defl

19、ection or rotation, or other signs of distress; Structures suspected to be substandard in design, detail,material, or construction; Structures where there is doubt as to the structuraladequacy and the original design criteria are not known; Structures undergoing expansion or a change in use oroccupa

20、ncy and where the new design criteria exceedthe original design criteria; Structures that require performance testing followingremediation (repair or strengthening); and Structures that require testing by order of the buildingofficial before issuing a Certificate of Occupancy.1.3ExceptionsThis repor

21、t does not address the following conditions: Performance testing of structures with unusual designconcepts; Product development testing where load tests arecarried out for quality control or approval of mass-produced elements; Evaluation of foundations or soil conditions; and Structural engineering

22、research.1.4Categories of evaluationThere are a number of different characteristics or levels ofperformance of an existing concrete structure that can beevaluated. These include: Stability of the entire structure; Stability of individual components of the structure; Strength and safety of individual

23、 structural elements; Stiffness of the entire structure; Durability of the structure; Stiffness of individual structural elements; Susceptibility of individual structural elements toexcess long-term deformation; Dynamic response of individual structural elements; Fire resistance of the structure; an

24、d Serviceability of the structure.This report deals with the evaluation of an existingconcrete building for stability, strength, and safety. Althoughnot intended to be an in-depth review of durability, this reportaddresses durability-related aspects so that the engineer isalerted to significant feat

25、ures that could compromise thestructural performance of an existing concrete building orits components, either at the time of the investigation orover time.1.5Procedure for a structural evaluationMost structural evaluations have a number of basic stepsin common. Each evaluation, however, should addr

26、ess theunique characteristics of the structure in question and thespecific concerns that have arisen regarding its structuralintegrity. Generally, the evaluation will consist of: Defining the existing condition of the building, including:1. Reviewing available information;2. Conducting a condition s

27、urvey;3. Determining the cause and rate of progression ofexisting distress;4. Performing preliminary structural analysis; and5. Determining the degree of repair to precede theevaluation. Selecting the structural elements that require detailedevaluation; Assessing past, present, and future loading co

28、nditionsto which the structure has and will be exposed underanticipated use; Conducting the evaluation; Evaluating the results; and Preparing a comprehensive report including descriptionof procedure and findings of all previous steps.1.6CommentaryEngineering judgment is critical in the strength eval

29、uationof reinforced concrete buildings. Judgment of qualifiedstructural engineers may take precedence over compliancewith code provisions or formulas for analyses that may notbe applicable to the case studied. There is no such thing as anabsolute measurement of structural safety in an existingconcre

30、te building, particularly in buildings that are deteriorateddue to prolonged exposure to the environment or that havebeen damaged in a physical event, such as a fire. Similarly,STRENGTH EVALUATION OF EXISTING CONCRETE BUILDINGS 437R-3there are no generally recognized criteria for evaluatingserviceab

31、ility of an existing concrete building. Engineeringjudgment and close consultation with the owner regardingthe intended use of the building and expected level of perfor-mance are required in this type of evaluation.The following conclusions regarding the integrity of astructure are possible as a res

32、ult of a strength evaluation: The structure is adequate for intended use over itsexpected life if maintained properly; The structure, although adequate for intended use andexisting conditions, may not remain so in the future dueto deterioration of concrete or reinforcing materials, orchanges are lik

33、ely to occur that will invalidate the eval-uation findings; The structure is inadequate for its intended use but maybe adequate for alternative use; The structure is inadequate and needs remedial work; The structure is inadequate and beyond repair; and The information or data are not sufficient to r

34、each adefinitive conclusion.1.7Organization of the reportThe remainder of this report is structured into thefollowing five chapters and two appendixes:Chapter 2 discusses what information should be gathered toperform a strength evaluation and how that information can begathered. Two primary topics a

35、re covered. The first is a reviewof existing records on the building. The second is the conditionsurvey of the building, including guidelines on the properrecognition of abnormalities in a concrete structure and surveymethods available for evaluation of structural concrete.Chapter 3 outlines procedu

36、res that should be used to assessthe quality and mechanical properties of the concrete andreinforcing materials in the structure. Discussion is includedon sampling techniques, petrographic, and chemical analysesof concrete, and test methods available to assess the mechanicalproperties of concrete an

37、d its reinforcement.Chapter 4 provides procedures to assess the past, present,and future loading conditions of the structure or structuralcomponent in question. The second part of the chapterdiscusses how to select the proper method for evaluating thestrength of an existing structure.Chapter 5 provi

38、des commentary on the conduct of astrength evaluation for an existing concrete structure.Analytical techniques are discussed, and the use of load teststo supplement the analytical evaluation is considered.Chapter 6 lists available references on the strength evalu-ation of existing concrete structure

39、s.Appendix A describes an in-place load test method underdevelopment.Appendix B briefly describes relevant documents forstrength evaluation of existing structures.CHAPTER 2PRELIMINARY INVESTIGATIONThis chapter describes the initial work that should beperformed during a strength evaluation of an exis

40、tingconcrete building. The object of the preliminary investigation isto establish the structures existing condition to obtain areliable assessment of the available structural capacity. Thisrequires estimating the concretes condition and strength andthe reinforcing steels condition, location, yield s

41、trength, andarea. Sources of information that should be reviewed beforecarrying out the condition survey are discussed. Availabletechniques for conducting a condition survey are described.2.1Review of existing informationTo learn as much as possible about the structure, allsources of existing inform

42、ation concerning the design,construction, and service life of the building should beresearched. A thorough knowledge of the original designcriteria minimizes the number of assumptions necessary toperform an analytical evaluation. The following list ofpossible information sources is intended as a gui

43、de. Not allof them need to be evaluated in a strength evaluation. Theinvestigator needs to exercise judgment in determiningwhich sources need to be consulted for the specific strengthevaluation being conducted.2.1.1 The original designMany sources of informationare helpful in defining the parameters

44、 used in the originaldesign such as: Architectural, structural, mechanical, electrical, andplumbing contract drawings and specifications; Structural design calculations; Change orders to the original contract drawings andspecifications; Project communication records, such as faxes, tran-scripts of t

45、elephone conversations, e-mails, and memo-randa, between the engineer of record and otherconsultants for the project; Records of the local building department; Geotechnical investigation reports including antici-pated structure settlements; and The structural design code referenced by the local code

46、at the time of design.2.1.2 Construction materialsProject documents shouldbe checked to understand the type of materials that werespecified and used for the building, including: Reports on the proportions and properties of the concretemixtures, including information on the admixtures used,such as wa

47、ter-reducers and air-entraining agents with orwithout chlorides, and corrosion inhibitors; Reinforcing steel mill test reports; Material shop drawings, including placing drawingsprepared by suppliers that were used to place theirproducts, bars, welded wire fabric, and prestressingsteel; formwork dra

48、wings; and mechanical, electrical,and plumbing equipment drawings; and Thickness and properties of any stay-in-place formwork,whether composite or noncomposite by design. Suchmaterials could include steel sheet metal and clay tile.2.1.3 Construction recordsDocumentation dating fromoriginal construct

49、ion may be available such as: Correspondence records of the design team, owner,general contractor, specialty subcontractors, and materialsuppliers and fabricators; Field inspection reports;437R-4 ACI COMMITTEE REPORT Contractor and subcontractor daily records; Job progress photographs, films, and videos; Concrete cylinder compressive strength test reports; Field slump and air-content test reports; Delivery tickets from concrete trucks; As-built drawings; Survey notes and records; Reports filed by