Dynamic model for train-track-bridge coupling system subjected to non-uniform seismic excitation

In order to analyze the effects of traveling wave effect on the running safety of a train running over a high-speed railway bridge subjected to earthquake action, a dynamic model for train-track-bridge system subjected to non-uniform seismic excitation was set up based on the train-track-bridge dynamic interaction theory and by introducing a seismic multi-support excitation mode. This dynamic model consists of a vehicle model with 35 degrees-of-freedom, a slab track model and an FEM (finite element method) bridge model. A simulated analysis program was compiled. As an example, a simply-supported beam bridge with a span of 32 m was modeled, and the dynamic responses of vehicle and bridge system under uniform and non-uniform El Centro seismic excitations were calculated. The analysis results show that the traveling wave effect has a great influence on the dynamic responses' amplitudes of the coupling system. When the train speed is 350 km/h and traveling wave speed is 300 m/s, the derailment coefficient, the wheel unloading rate and the wheel-rail lateral force reduce by 84.1%, 19.5% and 87.8% respectively compared with uniform seismic excitation. So, when the traveling wave effect is ignored, the judgment of the running safety of a train passing a bridge under earthquake action may be wrong.