Research On Seismic Reduction And Isolation Method For Railway Beam Under Near-Fault Ground Motions

In this thesis, the seismic responses of railway continuous beam subjected to near-fault and far-fault ground motions are compared by using the time history analysis method,and the seismic reduction and isolation of the bridges under near-fault ground motions have been analyzed. The main contents are as follows:1 The typical characteristics of near-fault ground motions have been elaborated. The differences between the spectrum characteristics of near-fault and far-fault ground motions are analyzed and compared.2 It is compared that the seismic responses of the railway continuous beam with different soil stiffness subjected to near-fault ground motions and far-fault ground motions by using the time history analysis method. Meanwhile, the effect of velocity pulse on the seismic response of railway continuous beam have been analyzed.3 Based on nonlinear time history analysis method, isolation effects of friction pendulum bearings and high damping rubber bearings under near-fault and far-fault ground motions are discussed, then a comprehensive research is conducted to study the influences of velocity pulse, PGV/PGA, curve radius of bearing, friction coefficient and height of piers on the performance of friction pendulum bearings. The influences of velocity pulse, support stiffness and yield ratio on seismic isolation performance of high damping rubber bearings are also studied.4 Based on nonlinear time history analysis method, damping effects of fluid viscous damper under near-fault and far-field ground motions are discussed, and a comprehensive research is conducted to study the influences of velocity pulse, damping coefficient and velocity index on damping performance of fluid viscous damper. Seismic reduction effects of fluid viscous damper and isolation effects of isolation device are analyzed and compared,and the influences of fluid viscous dampers on damping performance of irregular continuous beam are deeply studied and some suggestions for irregular continuous beam with seismic reduction design of fluid viscous dampers are put forward.