ACI 435.7R-85 State-of-the-Art Report on Temperature-Induced Deflections of

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1、ACI435.7R-85(Reapproved1997)State-of-the-ArtReportonTemperature-InducedDeflectionsofReinforcedConcreteMembersByACICommittee435D.R.BuettnerA.Scanlon*ChairmanChairman,SubcommitteeonThermalDeflectionsD.E.BransonJ.GrossmanG.M.SabnisR.G.DrysdaleC-T.T.HsuC.G.SalmonA.FarahS.V.Kulka

2、rniA.F.ShaikhS.K.Ghosh*M.S.MirzaJ.M.SpangA.B.GogateE.G.NawyM.K.TadrosM.V.PregnoffS.Zundelevich*MembersoftheSubcommitteethatpreparedthisreport.Synopsis:Thisreportsummarizesavailablemethodsforcalculatingde-flectionsofreinforcedconcretebeamssubjectedtotemperaturechange.Selectio

3、nofdesigntemperaturesandtemperaturegradientsisdiscussedaswellastheeffectsofcrackingonresponseintheserviceloadrange.Keywords:beams(supports);cracking(fracturing);deflection;modulusofelasticity;momentsofinertia;reinforcedconcrete;temperature;thermalgra-dient.Thefullreportappea

4、rsintheACIManualofConcreteSP-86waspublishedintheACIJOURNAL,Proceedings,V.Practice,Part3.ACI435.7R-85isavailableaspartof82,No.4,July-August1985.DeflectionsofConcreteStructures,SP-86.Anabstractof435.7R-12ACICommittee435INTRODUCTIONTemperaturechangescansignificantlyaffectdeflec

5、tionsofreinforcedconcretebuildingstructures.Deflectionsoccurinunrestrainedflexuralmemberswhenatemperaturegradientissetupbetweenoppositefacesofthemember.Incaseswheredeformationsduetotemperaturechangearerestrained,tensilestressesinducedinthemembercanresultincrackingandconseque

6、ntreductioninflexuralstiffness.Becausetemperatureeffectsdonotoftenaffecttheultimatelimitstateofthestructure,effectsoftemperatureondeflectionaresometimesnotconsideredindesign.However,ithasbeenstandardpracticetocomputethermalstressesanddisplacementsinstructuresfortallbuildingd

7、esign.Also,elongationandshorteningofbridgesuperstructuresandprecastconcretestructuresarenormallycomputedforsupportandexpansionjointdesigns.DeSerio(1)statesthat"Designingforthermalandshrinkagestressesisthemostneglectedpartoftoday'sdesignpractice."Withtheuseofhigherstrengthmat

8、erialsandmorerefinedmethodsofanalysistheneedtoconsidertemperatureeffectsisb