Mega-frame Structure, Static And Dynamic Elastoplastic Analysis Of Comparative Study

Mega-frame structure has been widely applied in china in recent years.The research on seismic performance of mega-frame structure has of great significance in theory and practical engineering application.Firstly, the development and the present situation of nonlinear static and dynamic analysis in the world were introduced in the thesis. The advantages and shortages were followed. Then, the basic theory was presented, and several typical nonlinear static analysis methods were discussed and compared.In this thesis, the pushover analysis method is applied to a 21-story concrete filled square steel tube-steel beam frame by using SAP2000 software.Plastic hinge were used to simulate nonlinear deformation in beam and column ends in order to simulate nonlinear deformation, and three load patterns were adopted with displacement control. In the result, we have got the curve of the base shearing force with the displacement of the top point, the story displacement angles, the story shearing force and the evolutionary curves of the plastic hinges when the structure arrives at the performance point, so we can discover the weakness and the destructive situation of the structure, and assess the seismic performance.The paper focuses on a Modal pushover Analysis Procedure presented by Chopra from UC Berkley, and improves the MPA method combined with Capacity Spectrum Method, making the analysis result even near the actual performances of structures in severe earthquake.At last, two earthquake waves are applied to analyze the nonlinear dynamic time history of structure, according to the comparative result of the improved modal pushover analysis, it can be seen that two methods are almost consistent. The results of examples demonstrate that the improved modal pushover analysis can consider effectively the influences of high frequency modes of structure in inelastic stage effectively. Performance objectives determined by MPA are more reliable than those determined by homogeneous distribution and triangle upside down distribution.