Designation:D6555−17StandardGuideforEvaluatingSystemEffectsinRepetitive-MemberWoodAssemblies1ThisstandardisissuedunderthefixeddesignationD6555;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONTheapparentstiffnessandstrengthofrepetitive-memberwoodassembliesisgenerallygreaterthanthestiffnessandstrengthofthemembersintheassemblyactingalone.Theenhancedperformanceisaresultofloadsharing,partialcompositeaction,andresidualcapacityobtainedthroughthejoiningofmemberswithsheathingorcladding,orbyconnectionsdirectly.Thecontributionsoftheseeffectsarequantifiedbycomparingtheresponseofaparticularassemblyunderanappliedloadtotheresponseofthemembersoftheassemblyunderthesameload.Thisguidedefinestheindividualeffectsresponsibleforenhancedrepetitive-memberperformanceandprovidesgeneralinformationonthevariablesthatshouldbeconsideredintheevaluationofthemagnitudeofsuchperformance.Theinfluenceofloadsharing,compositeaction,andresidualcapacityonassemblyperformancevarieswithassemblyconfigurationandindividualmemberproperties,aswellasothervariables.Therelationshipbetweensuchvariablesandtheeffectsofloadsharingandcompositeactionisdiscussedinengineeringliterature.Consensuscommitteeshaverecognizeddesignstressincreasesforassembliesbasedonthecontributionoftheseeffectsindividuallyorontheircombinedeffect.Thedevelopmentofastandardizedapproachtorecognize“systemeffects”inthedesignofrepetitive-memberassembliesrequiresstandardizedanalysesoftheeffectsofassemblyconstructionandperformance.Usersarecautionedtounderstandthattheperformanceimprovementsthatmightbeobservedinsystemtestingareoftenrelatedtoloadpathsorboundaryconditionsintheassemblythatdifferfromthoseofindividualmembers.Thisisespeciallytrueforrelativelycomplexassemblies.Forsuchassemblies,usersareencouragedtodesignthetestprotocolssuchthati...
