Vibration isolation analysis of elastic bearing based on train-track-bridge coupled vibration model

ABSTRCT: Elastic bearings have been used on simply supported bridges on high-speed railway in Taiwan to isolate train-induced vibration. However, their influence on dynamic behavior of the vehicle and bridge has not been fully investigated, and their vibration attenuation has not been quantificationally discussed. In this study, spring-damper elements with 12 degrees of freedom are established to simulate elastic bearings, and added to Train-Track-Bridge System. To explore the influence of elastic bearings on isolation performance, a simply supported box-girder bridge with a span of 32 m, was simulated as a case study. Based on the Train-Track-Bridge coupled vibration system, the influence of the elastic bearing on the response of the vehicle and bridge are firstly discussed. Wheel unloading rate and vertical acceleration of the vehicle are hardly influenced by the vertical stiffness of the bearing, yet influenced by the vehicle speed significantly. With the vertical stiffness of the bearing decreasing, the static component of the bridge response increases gradually, while the dynamic component of the bridge response firstly decreases and then increases. The analysis shows that the elastic bearing with suitable vertical stiffness won’t have negative effects on the response of the vehicle and bridge. Then the influence of elastic bearings on vibration isolation is researched. The analysis shows that, besides affected by the vertical stiffness of the bearing, the vibration isolation performance of elastic bearings might be also influenced by the vehicle speed. For the elastic bearing with vertical stiffness of 1800 kN/mm, the vibration attenuation is 14.64 dB in the frequency band of 0~80 Hz, and the vibration attenuation is 15.50 dB in the frequency band of 20~80 Hz, which makes the significant contributions to the vibration attenuation in the whole range. Because the natural frequency of the elastic bearing vibration isolation system exists in the frequency band of 10~20 Hz, vibration in the middle and high frequency band can be absorbed, and the vibration in its natural frequency range can be amplified. Based on the results, it can be seen that elastic bearings can be used to isolate vibration in the region where the environmental vibration needs to be controlled rigorously.