Study On Coupling Vibration And Probabilistic Statistical Characteristics Of Train-bridge System Under Near-fault Ground Motion

With the pursuit of high efficiency,high-speed railroads are developing rapidly.However,seismic activity in China is of high frequency,high intensity and wide distribution.A large number of high-speed railway lines pass through earthquake prone areas,and it is inevitable that trains will run on Bridges when earthquakes occur.Besides,the velocity pulse of near fault ground motion will aggravate the nonlinear response of bridge.Therefore,it is necessary to study the seismic response of train-bridge coupling considering the nonlinearity of pier material and the response under near fault ground motion.This thesis establishes a simulation model of train-bridge coupling system considering the material nonlinearity of bridge piers,taking the CRH3 high-speed train and simply supported girder bridge as the research objects.The simulation analysis of the train-bridge coupling system under different strengths,different ground vibrations and different vehicle speeds are carried out.The research content of this thesis is as follows:(1)Based on the finite element method and the basic theory of multi-body system dynamics,the finite element software ABAQUS and ANSYS were used to establish the plastic bridge pier model and the elastic bridge model respectively,and the multi-body dynamics software SIMPACK was used to establish the train model,and the SIMPACK-ABAQUS multi-domain interactive joint simulation interface command was written based on the rigid-flexible coupling method to establish the vibration simulation model of the train-bridge coupled system.(2)Based on nonlinear time history analysis method,four typical ground motions were selected as external excitation and applied to nonlinear train-bridge coupling system considering pier material by large mass method to study the dynamic response of train-bridge system under earthquake action.The results show that the nonlinear concrete pier has obvious plastic damage under strong earthquake,and the transverse response of the bridge is larger than that of the linear model.The train response of the nonlinear model is generally larger than that of the linear model,but it is also smaller than that of the linear model when the earthquake intensity is low.(3)Based on the impulse characteristics of near fault ground motion,pairs of near-fault and far-field ground motion under the same seismic event were selected as external excitation and applied to the train-bridge coupled system,and the dynamic response characteristics of the trainbridge coupled system under the action of near-fault ground shaking were studied through simulation analysis,and the effects of ground shaking intensity and travel speed on the response were explored.The results show that the dynamic response indexes of both the train and bridge subsystems under the near-fault ground motion were greater than those under the far-field ground motion.(4)Based on the method of random function,combining the power spectrum model with the Gabor wavelet model to simulate the acceleration time history curve of random near-fault ground motion,the stochastic probabilistic model of the dynamic response of high-speed railroad bridges under earthquakes was established,and the influence of train speed on the probabilistic statistical characteristics was explored.