Using elastic bridge bearings to reduce train-induced ground vibrations: An experimental and numerical study

In order to investigate the influences of elastic bearings on ground vibrations induced by trains traversing a bridge, a numerical model was established based on the combination of train/track/bridge and pier/pile/soil subsystems. The elastic bearings in the train/track/bridge subsystem were simulated by a spring-dashpot element. The two subsystems were linked by the bearing reaction forces, and the whole model was calculated in the time domain. The numerically computed ground vibrations were compared with measured ones to validate the model. On this basis, the influences of elastic bearings on train, bridge and ground responses were discussed. Results show that the dynamic responses of the train are hardly affected, while the dynamic responses at the pier top and on the ground are clearly attenuated in the frequency band above 40 Hz. Some increments in the frequency range 8-30 Hz can be observed around the eigenfrequency of the main girder-elastic bearing system. The laws of bearing stiffness influences on ground vibrations were similar for different stiffnesses of the elastic bearings. Within a distance of 15 m from the bridge, elastic bearings with stiffnesses of 2400, 2000 and 1600 MN/m can reduce ground vibrations. However, at locations more than 22.5 m from the bridge, ground vibrations may be close to or even a little larger than those of the rigid bearing case. When the elastic bearing has a stiffness of 1200 MN/m, ground vibrations are clearly decreased at all locations.