The effect of high-speed railway train on the seismic response of bridge under earthquakes

This study aims to discuss the effect of high-speed railway train on the seismic response of bridge girder under earthquakes especially pay attention to the possible response reduction to the bridge caused by vehicle, utilizing experimental and simulation methods. A 1:10 scale model for the train-track-bridge system was built and a highspeed train running test platform based on shaking table array was constructed for the seismic loading test at varying running speed. To account the effects of different earthquake characteristics, earthquakes under the four types of site soil in the far-field and near-field were selected. The vehicle was modeled in two kinds of ways to distinguish the effects of spring-mass vehicle and additional mass which means a vehicle was set with spring suspension and mass, while another with additional mass only. Through a large amount of numerical simulation dates to determine the distribution interval of specific reduction value caused by the vehicle under the earthquake. Results in running tests and numerical simulation indicate that the lateral acceleration of the bridge girder can be effectively reduced when the train is stationary. The reduced ratios were about 4%- 8% compared without train on bridges. As the speed increases, the response of bridge is generally intense and the reduction is also weakened. Similar reduction was not observed in the response of vertical earthquake excitations, and highfrequency earthquakes have adversely affected this kind of reduction. The main reason for the reduction of lateral seismic response of bridge girder in the presence of static vehicle can be attributed to the phase difference between vehicle and bridge caused by a mass damper-like action, and the additional mass cannot cause similar changes alone.