Study On Seismic Performance And Progressive Collapse Of Semi-Rigid CFST Frames With Endplate Connections

In order to investigate seismic performance and progressive collapse capacity of semi-rigid CFST frames with endplate connections, quasi-static test, finite element (FE) analysis and simplified calculation analysis of semi-rigid CFST frames with endplate connections were carried out. The main research was summarized in detail as follows:(1) Through testing of two semi-rigid CFST Frames under low cycle loading, the failure mechanism and key components’stress of the novel typed composite structures were investigated. Seismic performance such as hysteretic performance, ductility and energy dissipation were analyzed.(2) The FE model of semi-rigid CFST frames was established by using ABAQUS software. Horizontal load (P)-horizontal displacement (A) curves were recorded and analyzed. Compared with the experimental data, the accuracy of this model was evaluated. At the same time, the nonlinear full-range analysis was carried out, and the failure model and stress distribution law of the key components were discussed.(3) The simplified theoretical analysis model of semi-rigid CFST frames and joints with endplate connections was made based on SAP2000 software. The moment-rotation relations of connections were simulated by using spring elements in the models. The rationality and accuracy of the simplified calculation model were verified by a lot of test results.(4) The progressive collapse calculation model on a six-storey and four-bay plane semi-rigid CFST frames with endplate connections was developed, the alternate load path method and instantaneous load method were adopted to this kind of plane frame calculation models in nonlinear static and dynamic analysis. The results show that:in nonlinear static analysis, calculation index of the structure bearing capacity and ductility for extended endplate and flush endplate connection were lower than rigid connection; in nonlinear dynamic analysis, deformation of key components of the structure was reduced as well as joint connection stiffness was enhanced, at the same time, overall anti-progressive collapse capacity of structures was improved.