Study On The Behavior Of Seismic Mitigation And Isolation Of Curved Girder Bridges Subjected To Near-Fault Ground Motion

In this thesis, the seismic response of curve girder bridges with different radius of curvature subjected to near fault and far fault seismic waves was compared by using the time history analysis method. The seismic mitigation and isolation of curved girder bridges subjected to near-fault ground motion has also been analyzed. The main contents of the thesis are as follows:(1) The typical characteristics of near-fault ground motion were elaborated. By using of earthquake ground motion response spectrum, the Fourier spectrum and power spectrum, the near-fault ground motion frequency spectrum characteristics were analyzed in time domain and frequency domain respectively.(2)The natural vibration characteristics of the curved girder bridge have been studied when radius of curvature and the restraints of the curved girder bridge have been changed.(3) The seismic responses of the curved girder bridges with different radius of curvature subjected to near-fault ground motion and far-fault ground motion have been compared by using the time history analysis method. At the same time, the effect of velocity pulse and different restraint modes on the seismic response of curved girder bridges has been studied.(4) The seismic mitigation effectiveness of the curved girder bridges with lead-rubber bearing which were subjected to the selected near-fault ground motions and far-fault ground motions has been studied by using the nonlinear time history analysis method. The influence of the yield force and the support stiffness on the seismic isolation of lead-rubber bearings has been analyzed, and advice about how to optimize the isolation effect of lead rubber bearings was given. Through the establishment of three different models, It can be found that reasonable combination of the lead rubber bearings and friction pendulum bearings can further enhance the seismic performance of curved girder bridges than using alone one of reducing vibration isolation device. The effect of the bearing friction surface curvature radius and friction coefficient of friction pendulum bearings on the seismic response of curved girder bridges has been discussed, and advice about how to optimize the isolation effect of friction pendulum bearings was given.