钢结构基本原理课件 (15).ppt
Strength and Stiffness of Members under Combined Axial Forces and MomentsBasic Principles of Steel Structures 5.1.1DefinitionofMembersunderCombinedAxialForcesandMoments5.1.2StrengthofMembersunderCombinedAxialForcesandMoments5.1.3StiffnessofMembersunderCombinedAxialForcesandMoments5.1.1 Definition of Members under Combined Axial Forces and MomentsAmembersubjectedtothecombinedactionofaxialforceandbendingmomentatthesametimeiscalledamemberundercombinedaxialforcesandmoments.Fig.5.1SchematicdiagramofmembersundercombinedaxialforcesandmomentsDefinition1.1.NeNMForexample,thevariablesectioncolumnoftheindustrialplantisamemberundercombinedaxialforcesandmoments.Definition of Members under Combined Axial Forces and Moments5.1.1 Fig.5.2SchematicdiagramofavariablesectioncolumninanindustrialbuildingFig.5.3Diagramofforcesonabeam-column5.1.1 Definition of Members under Combined Axial Forces and MomentsFig.5.4Schematicdiagramofseveralcross-sectionformsCross-sectionforms2.2.StrengthStabilityStiffnessGlobalstabilityLocalstability5.1.1 Definition of Members under Combined Axial Forces and MomentsMembersundertensileforcesandmomentsBearingcapacitylimitstate:strengthServiceabilitylimitstate:stiffnessMembersundercompressiveforcesandmomentsSolid-webmembersBuilt-upmembersThecalculationcontents3.3.5.1.2 Strength of Members under Combined Axial Forces and Moments（1）三级标题FlexibleworkingstageThemaximumcompressionsideedgeyieldsPlastichingeFig.5.5Thedevelopmentofcross-sectionstressinabeam-columnwitharectangularsectionThecalculationsketch1.1.（1）三级标题Consideringtheplasticdevelopmentofthesection,calculateaccordingtotheelastoplasticdesignmethod.Unidirectionalbending:(5-1)Bidirectionalbending:(5-2)Strength of Members under Combined Axial Forces and Moments5.1.2 1 12 2Thecalculationformulae2.2.Forthefollowingthreecases,x=y=1.01 1Whendirectlyunderadynamicload;2 2Forbuilt-upmembersbentaboutvirtualaxes;3 3When;Strength of Members under Combined Axial Forces and Moments5.1.2 Instructions:5.1.3 Stiffness of Members under Combined Axial Forces and MomentsStiffnessiscontrolledbytheslendernessratioofthemember:1 12 23 3(5-3)
