Study On Seismic Performance Of Isolated Curved Girder Bridge And Its Optimization Of Isolation Device

The curved bridge is an important part of urban overpasses and highway bridges,and belongs to the complex irregular structure with serious bending-twisting coupling effect.The piers are subjected to an interaction of compositing bending-shear-torsion.The seismic damages of the curved bridge are very serious under strong seismic excitations.The performance of the curved bridge should be of more concerns.Compared with the traditional aseismic bridge,isolation devices can improve its seismic performance,whereas the seismic response of curved bridge becomes more complicated under seismic excitations.Therefore,it is necessary to investigate the seismic response of the isolated curved girder bridges.A three-span isolated curved girder bridge is selected for this study.The research mainly focuses on two sides,including seismic performance of the isolated curved girder bridge and its seismic vibration control.Based on ANSYS platform,the seismic performance of an isolated curved girder bridge and its optimization of isolation devices are conducted.The research work mainly includes the following parts:1.The effects of the key structural parameters on the dynamic characteristics of the isolated curved girder bridges are investigated.The three-dimensional finite element models of the isolated curved girder bridges are performed in the ANSYS platform.Then,based on the subspace iteration method,the modal parameters of the isolated curved girder bridges with different structural parameters are analyzed.2.The effects of the key structural parameters on seismic response of the isolated curved girder bridges are further investigated.Consideing different input angles of the seismic excitations,the input angles of the seismic excitations on seismic response of isolated curved girder bridges are analyzed.Based on this,the key structural parameters,including horizontal radius angles and pier heights,on seismic response of isolated curved girder bridges are researched.3.The effects of the mechanical parameters of the isolation devices on seismic response of an isolated curved girder bridge are investigated.An isolated curved girder bridge is selected for the seismic response analysis.The mechanical parameters,including yield force,the elastic stiffness and yield stiffness of isolation bearing,on the seismic response of the isolated curved girder bridge are analyzed in detail.The appropriate ranges of the parameters are determined.Then,the parameters of the isolation bearings are optimized based on the zero-order optimization method.4.The seismic performance of the isolated curved girder bridge with viscous dampers is investigated.According to seismic analysis results of the isolated curved girder bridge,the layout of viscous dampers is determined.Then,the seismic response of isolated curved girder bridge with viscous dampers is studied.Based on this,the parameters of viscous dampers,including damping coefficient and damping exponent,are optimized using zero-order optimization methods.Meanwhile,the optimized parameters are selected for the seimic analysis of the isolated curved girder bridge with viscous dampers,and the performance of the the isolated curved girder bridge with viscous dampers is analysized in detail.