Seismic system of long-span composite girder cable-stayed bridge

In order to study the seismic performance of long-span composite girder cable-stayed bridges with different seismic systems, a composite girder cable-stayed bridge with span (177+360+177) m is taken as the research object, and the dynamic analysis model of the whole bridge is established by using finite element software ANSYS. The structural seismic response analysis is carried out by using the non-linear dynamic time history analysis method. Based on the seismic response results of the traditional seismic system, the seismic responses of the bridge with ductile seismic system and isolation system are compared. The results show that under E2 earthquake, the ductile seismic system can form complete hysteretic loops in transition pier and auxiliary pier bottom unit, which can dissipate the seismic energy through plastic hinges. So ductile system can be used for seismic design of transition pier and auxiliary pier. However, the hysteretic curve formed by the plastic hinge at the bottom of the tower is not full hysteretic loop, which indicates that the seismic reduction effect of ductile seismic system at the bottom of the tower is poor and should be carefully adopted. In addition, through internal force analysis, it is found that the ductile system has the best effect on internal force limitation. Especially on the transition pier and auxiliary pier, the effects of the two systems at the bridge tower are similar. So seismic isolation system can be considered in addition to ductility system. Through displacement analysis, it is found that ductile system is the best for transition pier and auxiliary pier in terms of displacement limitation, and seismic isolation system is the best for the bridge tower girder connection. © 2020, Jilin University Press. All right reserved.