Study On Progressive Collapse Resistance Of Steel Tubular Frame With Outer Tubular Joints

In recent years,the assembled steel structure engineering developed rapidly.However,the structural progressive collapse was a kind of serious failure form,which often brought about disastrous consequences.Therefore,the study on the resistance of progressive collapse for the assembled steel structure had important theoretical significance and engineering application value.The alternate load path method was employed to study the resistance of progressive collapse for the assembled steel frame structure with outer tubular joint,the influence of joint effect on the resistance of structure progressive collapse was main study subjects,the main contents were as follows:(1)The research progress of resistance of structure progressive collapse at home and abroad was reviewed.(2)In this paper,the component method was used to analyze the outer tubular beam column joints,the components and their constitutive relations of the joints were determined,and the simplified component joint model was established.The finite element models of planar steel frame with outer tubular joints with rigid joint model and simplified component joint model were established with software ABAQUS6.11,and the alternate load path method was employed to study their resistance of structure progressive collapse.(3)The nonlinear static analyses for the two kinds of planar steel frame structures were carried out respectively,and the material nonlinearity and geometric nonlinearity were also considered during the process of analysis.The results showed that the resistance loads of progressive collapse for the steel frame structure with the simplified component joint model were lower than that based on the rigid joint model.It was shown that the joint effect had certain influence on the resistance of progressive collapse for the planar steel frame with outer tubular joints,which should be considered,otherwise,it would lead to unsafe results.(4)The nonlinear dynamic analyses for the two kinds of planar steel frame structures were carried out by the equivalent load instantaneous unloading method,andthe material nonlinearity and geometric nonlinearity were taken into account in the analysis.The results showed that the maximum vertical displacement of the failure point for the steel frame structure with the simplified component joint model was slightly larger than that for the steel frame structure with the rigid joint model,however,all of them were not collapsed.In addition,the dynamic amplification coefficient of the planar steel frame with outer tubular joints was studied,the dynamic magnification coefficient was suggested to be 1.5 when the rigid joint model were used,the dynamic magnification coefficient was suggested to be 1.8 when the simplified component joint model were adopted.