Research On Seismic Analysis Method Of Bridge With Ballastless Track

With the remarkable characteristics of high smoothness, big overall stiffness, low maintenance workload, the ballastless track has been widely used in high-speed railway in our country. The ballastless track structure reinforces the integrity between the bridge spans, and the coupling integration across different bridges was strengthened remarkablely under the earthquake. In this paper, the modeling methods of rail-bridge whole system finite element analysis model were studied according to the low-level and high-level earthquake. Based on the structure properties of ballastless track, the dynamic nonlinear finite element models were set up considering the track system,the influence of high-speed railway bridge seismic response considering the track system was systematically studied.The main research work is as followed:(1) Based on consulting a large number of domestic and foreign literature, the earthquake damage characteristics of railway bridge and track system, the bridge seismic research status considering track system and the development situation of the isolation bearings.(2) According to the requirements of the code for seismic, the modeling thoughts and methods of two-level rail-bridge whole system finite element analysis model considering the track system were put forward according to the low-level and high-level earthquake.(3) The composited bridge structure in the line beijing-shanghai as the research object, three kinds of finite element models were established. The first model which neglected the track system, the second model which thought the rail, rail plate and base plate into overall, the third model which thought them separately. The modal analysis method was applied to them. The effect on the dynamic properties of the railway bridge was discussed with the track system(4) The response spectrum method is adopted to analysis model-1 and model-2. The influence of the seismic responses of the bridge structure by the track system and subsequent structure was studied under the low-level earthquake. Through analysising the data, the model-2 should be used to doing the seismic analysis of the bridge under low-level earthquake, without considering the effect of subsequent structure.(5) In model-3, respectively using nonlinear spring element to simulate the lowresistance fasteners and the relationship between the displacement and resistance of the ballast, friction element in the finite element program to simulate the isolated bearings, the nonlinear time-history analysis method was adopted to analysis the model-3. The influence of the seismic responses of the bridge structure by the track system and subsequent structure was studied under the high-level earthquake. At the same time, the influence of isolated bearings performance by the rail system are discussed.The model-3 should be used to doing the seismic analysis of the bridge under high-level earthquake, considering the effect of subsequent structure. Through analysising the data, the rail system has played a role to limit the performance of isolated bearings.