Influence of ballastless track types on the vehicle running on HSR bridges during earthquakes

Recently, high-speed railway (HSR) lines have extended into near-fault earthquake zones in China. In these regions, due to the limited early warning times of near-fault earthquakes, the presence of vehicles on HSR bridges during such events can be unavoidable. This study introduces a refined numerical model to simulate the vehicle- track-bridge (VTB) coupling vibration under near-fault earthquakes. It uses this model to examine the impact of various ballast-less track types on the real-time dynamic behavior of the VTB during an earthquake. The results indicated that the longitudinal continuous track offers superior performance in limiting the displacements of bridge girders compared to the unit slab track, resulting in fewer fluctuations in the vehicle's dynamic responses at the girder ends for the former track type. In addition, the effects of the randomness of near-fault earthquakes on vehicle running safety performance on HSR bridges equipped with different tracks are assessed. The outcomes of vehicle running fragility on HSR bridges during earthquakes demonstrated that the longitudinal continuous track can decrease the vehicle running fragility relative to the unit slab track. These results provide insights for constructing HSR bridges in near-fault earthquake zones.