Research On Seismic Performance Of High-Speed Railway Bridge Considering Friction Pendulum Bearing Degradation

Friction pendulum bearing is reliable and high-performance device for bridge isolation,which has been extensively used in anti-seismic engineering as part of China’s infrastructure development.However,the railway network across China now includes bridges situated in harsh environments contaminated by industrial pollutants such as chloride ions and sulfur dioxide due to the construction of high-speed railways.This corrosive environment causes friction pendulum bearings to degrade rapidly,leading to failure.Therefore,it is essential to study the performance deterioration of these bearings under corrosive conditions to reveal the impact on the seismic performance of high-speed railway bridges.The present study conducted an accelerated corrosion test of the friction pair material of friction pendulum bearings and analyzed the influence of bearing performance degradation on the seismic performance of highspeed railway isolation bridges using nonlinear dynamic numerical simulation analysis with SAP2000 finite element analysis software.The paper’s main research contents and achievements are as follows:1.The study established an equivalent mechanical model of friction pendulum bearings to investigate how the sliding friction coefficient influences the mechanical performance of the bearings.Corrosion tests of the chloride salt immersion of the friction pair material of friction pendulum bearings were carried out,and the morphological changes and degradation patterns of the friction pair materials during the degradation test cycle were analyzed.The study demonstrated the influence of the corrosion environment on the dynamic and static friction coefficients of the sliding surface of friction pendulum bearings.After the degradation of bearing performance,the dynamic and static friction coefficients of the friction pair material surface significantly increased,with the dynamic friction coefficient showing a more pronounced increase than the static friction coefficient.2.A nonlinear dynamic analysis model,which considered the effect of soil piles,was established for high-speed railway isolation bridges.The study analyzed the dynamic response and vibration characteristics of the system under multiple seismic excitations.The study investigated the effect of the degradation of friction pendulum bearing performance on the dynamic response of essential structures,such as the main beam and piers,within the isolation bridge system.The study revealed that the degradation of bearing performance caused an increase in both the displacement and acceleration response amplitudes of the pier and main beam,while the displacement amplitude of the main beam decreased.The sensitivity of the dynamic response amplitude of the isolation bridge system to the degradation of bearing performance varied significantly under different seismic excitations.The closer the earthquake wave’s dominant period is to the bridge’s isolation period,the more pronounced are the changes in the dynamic response of the bridge system caused by the degradation of bearing performance.3.The study aimed to determine the impact of the degradation of friction pendulum bearing performance on the energy response of high-speed railway isolation bridges under different seismic excitations.The analysis focused on the changes in various response energies,including the connection hysteresis energy dissipation and system kinetic energy,with respect to the degree of degradation of bearing performance.The energy dissipation ratio of friction pendulum bearings and the trend of mechanical energy change in the system were also analyzed.The results showed that after the degradation of bearing performance,the input seismic energy of the isolation bridge system significantly increased,and there was a slow decreasing trend in the isolation ratio of the friction pendulum bearing.Moreover,when the bridge encountered certain types of seismic excitations after the degradation of bearing performance,the overall mechanical energy of the isolation bridge system decreased to some extent.