The Collapse Analysis Of The Steel Structure Of Mega Frame With Upper Suspension And Lower Compression Of CAS Center For Excellence In Quantum Information And Quantum Physics

At present,the conventional structural design can basically guarantee the safety of the structure under normal use,but the building structure will always be threatened by explosion,typhoon,fire and earthquake during the whole service period,and cause collapse of the structure,the safety of the structure is still facing severe challenges.At present,researches on collapse resistance mainly focus on frame structures,shear wall structures and long-span spatial structure,while researches on mega-frame structure and suspension structure are few,especially on the steel structure of mega frame with upper suspension and lower compression.In this paper,based on Open Sees program,the progressive collapse resistance and lateral incremental collapse resistance of the steel structure of mega frame with upper suspension and lower compression of the CAS Center for Excellence in Quantum Information and Quantum Physics 1st Building were studied by means of alternative load path method and IDA method.The research work was as follows:?1?The theories of progressive collapse analysis including the alternative load path method,evaluation method of components importance,load combination,collapse failure criterion were summarized,and the method of progressive collapse analysis applicable to the steel structure of mega frame with upper suspension and lower compression was defined.The theories of lateral incremental collapse analysis were summarized,ground motion selection and amplitude modulation criteria,selection method of Intensity Measure and Damage Measure,collapse criteria,seismic fragility,collapse margin ratio and annual rate of collapse were summarized,and the method of lateral incremental collapse analysis applicable to the steel structure of mega frame with upper suspension and lower compression was defined.?2?Using Open Sees program,FE analysis model of the steel structure of mega frame with upper suspension and lower compression was establish by appropriate constitutive models of materials,element model,etc.The accuracy and reliability of the FE model was verified by comparing the period of the structure under Open Sees and Midas/gen and comparing Open Sees calculation results with results obtained from dynamic tests.?3?The importance factor of truss members was calculated with stress as sensitivity index.4 cases of important truss members failures,2 cases of bottom frame columns failures,6 cases of important suspension columns failures and 2 cases of multiple members failure were set,equivalent load transient unloading method was used to consider the dynamic effect,the deformation and internal force response of the structure after members failure were analyzed based on alternative load path method.From the aspects of deformation criterion and strength criterion,the progressive collapse resistance of the steel structure of mega frame with upper suspension and lower compression from the aspects of deformation criterion and strength criterion was evaluated,and recommendations of progressive collapse resistance were proposed.?4?The structure were explored by elasto-plastic time history analysis.IDA analysis was carried out on the structure with S_a?T₁,5%?and PGA as the Intensity Measure.The probalistic seismic fragility of the structure was studied and the collapse margin ratio of the structure was calculated.The ground seismic hazard analysis was carried out and the annual exceeding probability of collapse state was calculated,and the lateral incremental collapse resistance of the steel structure of mega frame with upper suspension and lower compression was evaluated.