Nonlinear Seismic Response Analysis Of Long-span Cable-stayed Bridge Considering Site Effect

Based on the actual engineering design requirements,the seismic response of the cable-stayed bridge site and the influence on the seismic response of the structure were studied based on the site survey data.Based on the site conditions,32 representative bedrock seismic waves were selected.The equivalent linear and nonlinear models were used to analyze the seismic response of the bridge site,and then the influence of different models on the seismic response of the bridge structure was studied.In addition,based on the OpenSees finite element software,a three-dimensional finite element model of a cable-stayed bridge was established and nonlinear time-history response analysis was performed.The main content of the paper is as follows:1)Based on the actual geological survey data of a cable-stayed bridge,taking into account the influence of site soil properties on ground motion propagation,two types of site soil analysis models for the actual field of the cable-stayed bridge are established based on equivalent linear and nonlinear theory.According to site conditions,32 representative ground motions were screened.2)Based on the established equivalent linear and nonlinear models,the seismic response of the site under the action of 32 ground motions is calculated,and the change law of the site seismic response and the influence on the seismic response of the superstructure are analyzed.3)Based on the OpenSees open source finite element platform,the nonlinear finite element model of the cable-stayed bridge is established,and the modal analysis is used to obtain the first ten vibration modes and corresponding cycles of the cable-stayed bridge,and MIDAS CIVIL,commonly used in the finite element analysis of practical projects,is obtained.Compared with the modal analysis results obtained by the MIDAS CIVIL model,the correctness and rationality of the OpenSees dynamic analysis model used in this study were verified and verified.4)Based on the nonlinear finite element model of cable-stayed bridges,based on the OpenSees platform,the nonlinear seismic response of cable-stayed bridges under the action of22 # and 23 # three-dimensional ground motions was calculated,considering the amplification effect of the site on ground motions.The seismic responses of bearings,bridge piers,bridge towers,main girders and cables are analyzed respectively,and conclusions about the nonlinear seismic response of such long-span cable-stayed bridges are obtained.