Research On Seismic Behavior Of Composite Structural Systems With Separated Gravity And Lateral Resisting Systems

The prefabricated composite structures have the advantages of high bearing capacity,high overall stiffness and high construction efficiency,which have a broad application prospect in engineering construction.In this thesis,a new composite structural system with separated gravity and lateral resisting systems is proposed to meet the development needs of prefabricated composite structures.The seismic behavior of this structural system is investigated,focusing on the force mechanism,deformation characteristics,failure mode and numerical model,and the seismic damage assessment method of the structural system is proposed.The main research works and results are as follows:(1)Three large scale tests on the mechanical performance of the structural system are completed.Based on the test results,the differences in seismic behavior between the new structural system and the traditional rigid composite frame are compared.The force mechanism,deformation characteristics and damage patterns under vertical floor loading and horizontal cyclic loading are analyzed,respectively.The seismic performance of the two structural systems are evaluated by the demand spectrum method,and the semirigidity of the connections in the new structural system is initially discussed.(2)The mechanism of the composite structural system with separated gravity and lateral resisting systems is investigated using the three-dimensional fine element model.A shell-solid mixed model is established on the general FE package MSC.MARC,and a simulation method considering the weld fracture problem is proposed.The force and deformation characteristics,buckling patterns and failure modes of different components in the new structural system are analyzed.(3)An efficient numerial model of the composite structural system with separated gravity and lateral resisting systems is established.An analytical model of the semi-rigid connections in the new structural system is proposed based on the basic idea of component method.A connection element is realized based on the secondary development function of the general FE package MSC.MARC,which forms an efficient analysis model for the new structural system by extending the subroutine package for the nonlinear analysis of composite structures COMPONA-FIBER.(4)The hysteresis behavior of the composite structural system with separated gravity and lateral resisting systems under seismic action is studied through the application of the self-developed numerial model.Elasto-plastic history analysis is carried out on a six-story office building to investigate the seismic mechanism of the new structural system and the effect of semi-rigidity of connections on the seismic behavior of the overall structure.(5)A seismic damage assessment method is established for the composite structural system with separated gravity and lateral resisting systems.Considering the damage characteristics of the new structural system under seismic action,the story curvature is selected as the seismic damage assessment index.The critical damage states of the composite shear wall are determined based on the cross-sectional analysis method.Based on the seismic damage assessment method,the influence mechanism of the key structural parameters on the seismic damage behavior of the structural system is discussed.