1、1Determining the LoaD CapaCity of a StruCture When aS-BuiLt DraWingS are unavaiLaBLeKeywords: foundation capacity; gravity and lateral loads; investigation program; load capacity; load testing; material properties; structural con-figuration; visual examination.IntroductionIn cases where a structural
2、 evaluation is to be performed, knowledge of member sizes, reinforcing details, and material properties is generally renullired. In cases where this information is not readily available through drawing document records, it should still be obtained. nullr most buildings, bridges, and structures gover
3、ned by a building code or similar design standards, the process to establish load capacity typically needs approval of the governing official.Questionnullw can the load capacity of a structure be determined when as-built structural drawings are not availablenullAnswerIn the absence of drawings, the
4、engineer should develop and implement an investigation program involving visual inspection, material testing, nondestructive testing nullnullnull and calculations to form a rational basis for determining the structural capacity. nullgineers should rely on their knowledge, experience, and nulldgment
5、to develop an approach that is valid and cost-effective. nulle following discussion is intended to assist engineers in developing such an approach.Discussionnullerivation of load-carrying capacity and other critical behavioral characteristics renulluires the involvement of a structural engineer with
6、 strong experience in this field. nulletermining the structurenulls age may provide some idea of what the building code renulluirements were at the time of construction. nullany historic reinforced concrete struc-tures, however, were designed using systems that are no longer used and are not address
7、ed in modern codes and design practices. nullructural configuration and reinforcement may be established using the general techninulles described in nullI nullnullnullnullnullnullI nullommittee nullnullnull nullnullnullnullnull and nullnullnullInullnullnullnullnull nullnull-nullnull nullnullnullnull
8、nullnull. nullisual examination and physical measure-ments are made in connullnction with nondestructive examination and examination after removal of concrete nullnull nullmmittee nullnullnullnull; nullnullnullInullnullnullnullnull nullnull-nullnull nullnullnullnullnull. nullaterial properties nullc
9、oncrete and reinforcement strengthnull may be determined by physical testing nullnull nullmmittee nullnullnullnull, nullnullnull nullinforcement size and strength may also be determined through observation of mill imprinted markings on exposed bars nullnullI nullnual of nullandard nullac -ticenull n
10、ullce the structural system, reinforcement, and material properties are known, the structural capacity may be determined through calculations. nullsearch into the testing and design procedures for historic structural systems may provide valuable clues about reinforcement configuration and structural
11、 behavior nullnullI nullnull nullnual of nullandard nullacticenullnullisual examinations and physical measurements are suggested to define the overall structural system for resisting both gravity and lateral loads. nullnderstanding the lateral load-resisting system is necessary to properly consider
12、the structural effects of lateral loads on elements such as slabs, beams, columns, walls, and foundations.nullce the basic structural configuration is known, the actual layout of reinforcement may be determined. nullere the depth of cover is less than null in. nullnullnull mmnull, the size, spacing,
13、 and depth of the cover of reinforcement in typical structural members can usually be established using a pachometer. nullchometer surveys may be partially effective where the depth of cover ranges from nullto nullin. nullnullto nullnullmmnull nullchometer surveys may be problem -atic in areas of co
14、ngested reinforcement, such as columns and beams and at areas of metallic surface interference nullfor example, metallic conduitsnull. nulldditional exploratory openings may be renulluired, and other methods, such as x-ray or ground-penetrating radar surveys, may be necessary to determine internal r
15、einforcing pattern arrange-ments. nulle pachometer survey results should be spot-checked by physical measurement of exposed reinforce-ment at exploratory openings.ACI 364.4T-10TechNoteAmerican Concrete Institute Copyrighted Materialwww.concrete.org2 DETERMINING THE LOAD CAPACITY OF A STRUCTURE WHEN
16、AS-BUILT DRAWINGS ARE UNAVAILABLE (ACI 364.4T-10)nullocedures are available to provide guidance on sampling and testing concrete nullnullnullnullnullnullnull nullnullnullnull, nullnullnullnullnullnulland reinforcing nullnullnullnullnullnull nulle reliability of material properties established by tes
17、ting concrete cores and reinforcement samples is a function of the number of samples. nullhe extent of sampling and testing is a matter of professional nulludgment, and may depend on the confidence level necessary and the consistency of the findings nullnullnullnullnull nullnullnullnull; nullnullI n
18、ullnullnullnull; nullnullI nullnullnull.nullnullnull. nullore tests may be supplemented by other strength evalua-tion tests, such as rebound hammer tests and probe penetration tests. nullchanical reinforcement tests may be supplemented by in-place hardness tests and by metallurgical analysis of fili
19、ngs. nullith the member sizes, patterns, and material properties known, calculations may be performed to establish the structurenulls load-carrying capacity. nullter computing the superimposed load capacity of one area or bay of a structure, it is recommended that similar analyses be performed on ad
20、nullining areas. nulltermining consistent load capacity results in separate areas of a structure may be considered a prudent method to confirm the overall analysis. If the member dimensions, reinforcing size and spacing, and material properties are well estab-lished by measurement and testing, then
21、strength-reduction factors may be increased in accordance with the guidelines and within the limits identified in nullapter null of nullI nullnull nullofessional nulldgment is important in this regard, especially where constraints have limited the extent of testing and on-site exploration. nulload t
22、esting nullnullnullI nullnullnull; nullnullI nullnullnullnull, nullnullnull.nullnullnull is another tool for determining the load-carrying capacity of a member or structure. nullad tests conducted in accordance with nullapter null of nullI nullnulland nullI nullnull may be used to verify the load ca
23、pacity of a given structure. nullad testing may reduce, but not completely eliminate, the need for investigative field work, material testing, and structural calculations. nulletermining the most efficient combina-tion of investigative field work, material testing, structural calculations, load test
24、ing, or a combination of these depends on professional nulludgment and on an evaluation of the practical difficulties associated with each item. nullch structure should be evaluated on a case-by-case basis.null a final consideration, the capacity of the foundation system may need to be determined, e
25、specially in cases where the load capacity of an entire structure is being established. nullhe foundation may need to be exposed and the soil-bearing capacity determined in the case of shallow foundations. nullhere deep foundations are used, some excavation may be renullired to determine the type of
26、 deep foundation, supplemented by other procedures such as nullnull, coring, probing, load testing, or other means to reliably predict the foundation capacity. nullhe original soil test boring records or a subsurface investigation report, if available, are valuable in establishing the likely foundat
27、ion system employed in the building. nullcking this, an engineernulls knowledge of subsurface conditions or records for adnullcent buildings may aid in this aspect of the analysis. nullhe strength of the superstructure members is independent of the foundation, but the capacity of the foundation may
28、limit the load that can be applied to the superstructure members. Summarynullhe load capacity of a structure can be determined when as-built drawings are unavailable. nulln engineering inves-tigation involving visual inspection, material testing, and nullnullnull provides a basis for rational calcul
29、ations to determine the structural capacity. Referenced standards and reportsnulle standards and reports listed below were the latest editions at the time this document was prepared. nullcause these documents are revised frenullently, the reader is advised to contact the proper sponsoring group if i
30、t is desired to refer to the latest version. American Concrete Institutenullnull nullaluation of nullrength null est nullsults of nullncretenullnullnull nullide for nulltaining nullres and Interpr eting nullmpressive nullrength nullsultsnullnullnull In-nullace nullthods to nulltimate nullncrete null
31、r engthnullnullnull nullndestructive null est nullthods for nullaluation of nullncrete in nullructuresnullnullnullnull nullilding nullde and nullmmentarynullnullnull nullide for nullaluation of nullncrete nullr uctures before nullhabilitationnullnull nullrength nullaluation of nullisting nullncr ete
32、 nullildings nullnullnull nullad nullests of nullncr ete nullructures: nullthods, nullgnitude, nullotocols, and nullceptance nulliteriaASTM Internationalnullnull nullandard null est nullthods and nullfinitions for nullchanical nullesting of nulleel nulloductsnullnullnullnull nullandard null est null
33、thod for nullmpressive nullrength of nulllindrical nullncrete nullecimensnullnullnullnull nullandard null est nullthod for nulltaining and nullesting nullilled nullres and nullwed nullams of nullncreteDETERMINING THE LOAD CAPACITY OF A STRUCTURE WHEN AS-BUILT DRAWINGS ARE UNAVAILABLE (ACI 364.4T-10)
34、 3American Concrete Institute Copyrighted Materialwww.concrete.orgnullnullnullnullnull nullandard nullactice for nullamination and nullmpling of nullr dened nullncrete in nullnstructionsnullnull nullandard nullactice for nulloice of nullmple nullze to nulltimate a nullasure of nullality for a nullt
35、or nullocessConcrete Reinforcing Steel Institutenullnull nullnual of nullandard nullacticeCited referencesnullnullnullInullnullnullnullnull nullnull-nullnull, nullnullnullnull, nullnulluideline for nulltructural nullondition nullssessment of nullxisting nulluildings nullnullnullnullnull null-nullnul
36、lnull,nullnullinimum nullesign nulloads for nulluildings and nullther nulltructures, nullmerican nullociety of nullivil nullngineers, nullew nullork, nullnullnull pp.nullnullnullI, nullnull, nullvaluation of nullinforcing nullrs in nulld nullinforced nullncrete nullructures,nullnullgineering nullta
37、nullport null. null, nullicago, InullnullnullI nullechnullotes are intended for reference for the design and construction of concrete structures. nullhis document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and who will accept
38、responsibility for the application of the information it contains. nulle nullerican nullncrete Institute disclaims any and all responsibility for the accuracy of the content and shall not be liable for any loss or damage arising therefrom. nullference to this document shall not be made in contract d
39、ocuments.nullI nullnullnull-null was adopted and published nullnuary nullnull.nullpyright nullnullnull, nullerican nullncrete Institute.nullll rights reserved including the rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electron
40、ic 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 obtained from the copyright proprietors.For additional copies, please contact: American Concrete Institute, 388
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