Anti-Seismic Performance Analysis For Long-Span Continuous Rail Transit Bridge

With the rapid development of urbanization in china,city rail transit construction has entered a fast-developing new stage.As an important component of city rail transit construction,the research on seismic performance for urban rail transit Bridge is of great significance.This paper is based on a long-span rail transit bridge in the first phase project of Tianjin Binhai new area Z4 line.A rail-bridge model is established by finite element software,considering the influence of pile-soil interaction.To explore the influencing factors of dynamic characteristics of long-span railway bridge.The major works and achievements are as follows:1.In this paper,considering the orbit constraint of rail-bridge model and method of determining parameter.The natural vibration characteristics of the whole structure are calculated.Compare The difference of the natural frequency of pile fiexd and pile-soil interaction.The results showed that considering the pile-soil interaction,the natural vibration frequency of the whole structure is obviously changed.Therefore,the influence of pile-soil interaction should be taken into account when analyzing the seismic performance of this project.2.The response spectrum analysis and dynamic time history analysis of the whole model are carried out and studied the effect of track restraint on the natural frequency of the structure and the seismic response of the anchor block.The results showed that the natural frequency of cis-bridge and the seismic response of the anchor block are improved by considering the constraint of track.However,it has little effect on the natural frequency and seismic response of the cross-bridge.Therefore,it is not safe to ignore the constraint of the track when analyzing the seismic response of the anchor block.3.The influence of pile-soil interaction on seismic analysis results is calculated based on m method and p-y curve method respectively.The results showed that the bending moment and deflection of the piles are significantly increased,the seismic response of the pile foundation is improved significantly in the position of anchor block.Therefore,the m method is not suitable and safe for the performance analysis of the structure,so as to ensure the safety of calculation results.It is suggested that the p-y curve method or other reliable methods should be used to calculate the seismic response of the project,especially the seismic response of the pile foundation.4.Using FPB friction pendulum isolation bearing of bridge for seismic analysis,and studied the influence of anchor block height on FPB friction pendulum isolation performance.The results show that using FPB friction pendulum bearings can significantly reduce the seismic response of the anchor block,and with the increase of the height of anchor block,FPB friction pendulum seismic isolation effect gradually decreased.