1Example39Title2-D,7-storyframebuildingunderstaticanddynamicloadsDescriptionAssumethateachfloorofthestructureillustratedbelowactsasarigiddiaphragm.Calculatethenaturalfrequencies.Performanalysesforstaticlateralloads,earthquakeloadsspecifiedasaresponsespectrumandearthquakeloadsspecifiedasabaseaccelerationtimehistory.Calculatetheaxialforcesandmoments.2StructuralgeometryandanalysismodelExample393Sectionpropertiesof7-storyplaneframebuilding4ModelAnalysisTypeResponsespectrumandtimehistoryanalysesUnitSystemin,kipDimensionLengthL=60×12inLevelheightH1=13×12+6in(1st~2ndfloor)H2=13×12in(3rd~7thfloor)FloormassM=0.49kips∙sec2/inDampingratioξ=0.05(5%)Gravitationalaccelerationg=386.4in/sec2Responsespectrumdata1941ElCentroN-ScomponentElementBeamelementMaterialModulusofelasticityE=29500ksiSectionPropertyRefertothefigureshownabove.AreasandmomentsofinertiaforcolumnsC1:A=51.17in2Iyy=2150in4C2:A=62.10in2Iyy=2670in4C3:A=72.30in2Iyy=3230in4C4:A=84.40in2Iyy=3910in4AreasandmomentsofinertiaforbeamsExample395B1:A=50in2Iyy=3330in4B2:A=50in2Iyy=4020in4B3:A=50in2Iyy=5120in4BoundaryConditionNodes1~3;ConstrainDy,DzandRx.Nodes4~22;ConstrainDyofallnodesateachfloortothesenodes.(atanincrementof3)(Masternodes)LoadCaseStaticverticalloads;Thefollowingloadsareappliedtoeachfloorinthe-Zdirection.:Uniformlineload=0.1kips/ft=0.1/12kips/inEachspanissubjectedtotwoconcentratedloads,20.0kipseachStaticlateralloads;ThefollowingloadsareappliedtothemasternodesoneachfloorintheYdirection.Node4(2ndlevel):2.5kipsNode7(3rdlevel):5.0kipsNode10(4thlevel):7.5kipsNode13(5thlevel):10.0kipsNode16(6thlevel):12.5kipsNode19(7thlevel):15.0kipsNode22(Rooflevel):20.0kipsDynamicloads;FloormassesareassignedtothemasternodesateachfloorintheYdirection.TheresponsespectrumdataoftheElCentroN-ScomponentareappliedintheYdirection.Numberofnaturalfrequenciestobecomputed=7Earthquakeloads;TheN-SaccelerationcomponentoftheELCentroisappliedtotheentirestructureintheYdirection.6LoadCaseEX39-1LoadCase1:StaticverticalloadsLoadCase2:Staticlaterallo...
