Dynamic Response Analysis Of Train-bridge Spatial Coupling System Under Earthquake

Earthquakes are serious nature disaster. Earthquakes may cause a series of problems in rail system, for example, rail bent, train derailed and bridges collapsed. With the development of high speed railways, the proportion of bridges is growing constantly in railway lines, and the probability of train running on bridges when earthquakes occurred also is larger. In order to explore the impact of earthquakes on train and bridges, the spatial model of train-bridge coupling system was established. The vehicle was simulated as rigid multi-body system, using the D’Alembert principle to derive vehicle system dynamics equations. The bridge was assumed as a simply supported beam with uniform mass distribution, building generalized coordinates equations of the bridge by modal coordinate method. The normalized seismic wave was a kind of system stimulation, meanwhile, the influence of track random irregularity was considered. The system equation was solved by new explicit integration method. The dynamic responses of the coupled system of train-bridge under earthquakes of different intensity were analyzed. The numerical results show that earthquakes have significantly effect on the dynamic responses of the coupled system of train and bridge. No matter in vertical or horizontal, both the acceleration and deflection response of the bridge can meet the limit requirements of norms when earthquakes intensity is within the scope of the bridge’s seismic fortification intensity, The Sperling index of vehicle stability is relatively looser than acceleration index, and the vehicle can’t run steady on the bridge when seismic intensity is seven degrees or above. The derailment coefficient of the vehicle increase rapidly with the speed increases, when an earthquake occurs, braking measures need to be taken to avoid accidents. The track random irregularity doesn’t have an obvious effect on dynamic response of the vehicle, but it is relatively obvious to vertical acceleration response of the bridge. Under a relatively weak earthquake, for a detailed study of dynamic response of the bridge, the track random irregularity shouldn’t be ignored. With the increase of earthquake intensity, the influence of track random irregularities becomes smaller and smaller.