Fundamentals of beam bracing

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1、FundamentalsofBeamBracingJOSEPHA.YURAINTRODUCTIONinfinitywhenthebucklingloadisreachediftheidealbracestiffnessisused.Thus,abracesystemwillnotbesatisfac-hepurposeofthispaperistoprovideafairlycompre-Ttoryifthetheoreticalidealstiffnessisprovidedbecausethehensiveviewofthesubjectofbeamstability

2、bracing.braceforcesgettoolarge.Ifthebracestiffnessisoverde-Factorsthataffectbracingrequirementswillbediscussedsigned,asrepresentedbyβL=2βiand3βicurvesinFigureanddesignmethodsproposedwhichareillustratedby2(b),thenthebraceforceswillbemorereasonable.Foradesignexamples.Thedesignexamplesemphas

3、izesimplic-bracestiffnesstwicetheidealvalueanda∆o=Lb/500,theity.Beforegoingintospecifictopicsrelatedtobeambrac-braceforceisonly0.8%PeatP=Pe,notinfinityasintheing,someimportantconceptsdevelopedforcolumnbracingidealbracestiffnesscase.ForabracestiffnesstentimesthebyWinter(1960)willbepresente

4、dbecausetheseconceptsidealvalue,thebraceforcewillreduceevenfurtherto0.44willbeextendedtobeamslater.percent.AtPcrthebraceforcecannotbelessthan0.4%PForaperfectlystraightcolumnwithadiscretemidheightcorrespondingto∆T=∆o(aninfinitelystiffbrace)for∆o=bracestiffnessβL,therelationshipbetweenPcran

5、dβLisLb/500.FordesignFbr=1%PisrecommendedbasedonashowninFigure1(TimoshenkoandGere,1961).Thecol-bracestiffnessoftwicetheidealvalueandaninitialout-of-umnbucklesbetweenbracepointsatfulloridealbracing;straightnessofLb/500becausetheWintermodelgivesinthiscasetheidealbracestiffnessβi=2Pe/Lbwhere

6、Pe=slightlyunconservativeresultsforthemidspanbraceprob-π2EI/Lb2.Anybracewithstiffnessuptotheidealvaluewilllem(Plaut,1993).increasethecolumnbucklingload.Winter(1960)showedPublishedbracingrequirementsforbeamsusuallyonlythateffectivebracesrequirenotonlyadequatestiffnessbutconsidertheeffectof

7、bracestiffnessbecauseperfectlyalsosufficientstrength.Thestrengthrequirementisstraightbeamsareconsidered.Suchsolutionsshouldnotbedirectlyrelatedtothemagnitudeoftheinitialout-of-useddirectlyindesign.Similarly,designrulesbasedonstraightnessofthemembertobebraced.strengt