简介：Thisstudyinvestigatedcharacteristicsofbifurcationandcriticalbucklingloadbyshapeimperfectionofspacetruss,whichweresensitivetoinitialconditions.Thecriticalpointandbucklingloadwerecomputedbytheanalysisoftheeigenvaluesanddeterminantsofthetangentialstiffnessmatrix.Thetwo-free-nodesexampleandstardomewereselectedforthecasestudyinordertoexaminethenodalbucklingandglobalbucklingbythesensitivitytotheeigenbucklingmodeandtheanalysesoftheinfluence,andcharacteristicsoftheparametersasdefinedbytheloadratioofthecenternodeandsurroundingnode,aswellasrise-spanratiowereperformed.Thesensitivitytotheimperfectionoftheinitialshapeofthetwo-free-nodesexample,whichoccursduetosnappingatthecriticalpoint,resultedinbifurcationbeforethelimitpointduetothebucklingmode,andthebucklingloadwasreducedbytheincreaseintheamountofimperfection.Thetwosensitivebucklingpatternsofthenumericalmodelareestablishedbyinvestigatingthedisplacedpositionofthefreenodes,andtheasymmetriceigenmodegreatlyinfluencedthebehavioroftheimperfectionshapewhetheritwasatlimitpointorbifurcation.Furthermore,thesensitivemodeofthetwo-free-nodesexamplewassimilartothein-extensionalbasismechanismofasimplifiedmodel.Thestardome,whichwasusedtoexaminetheinfluenceamongseveralnodes,indicatedthattheinfluenceofnodalbucklingwasgreaterthanthatofglobalbucklingastherise-spanratiowashigher.Besides,globalbucklingisoccurredwithreachingbifurcationpointasthevalueofloadratiowashigher,andthebucklingloadlevelwasabout50%-70%ofloadlevelatlimitpoint.