Numerical investigation of bearing damage impact on vertical vibration performance of train-track-bridge interaction system for three-span continuous box girder bridges

As a critical component of bridges, bearings easily suffer damage when exposed to various loads and environmental changes during their lifetime. Bearing damage will change the boundary conditions of the bridge, thereby affecting the responses of the train-track-bridge interaction (TTBI) system. This paper investigates the influence of bearing damage on the vertical vibration performance of TTBI system in a three-span continuous box girder bridge. Finite element models, incorporating the elastic behaviour of bearings, are employed to simulate the bearing damage at different positions and severities. The variation law of the normalised vibration response of the TTBI system and the dynamic reaction force of bearings are analysed. Results indicate that bridge displacement is far more sensitive to bearing damage than acceleration response, while this opposite for the train. Bearing damage induces a redistribution of reaction forces in the nearby area, while exerting relatively small impact on reaction forces of the bearings located farther away. The amplification effect of two bearings damaged simultaneously on system response is not a simple superposition of the ones of individual bearing damage, but involves complex coupling effects.