基于移动荷载过桥的轨道交通桥梁振动研究

应用振型分解法,对移动荷载通过轨道交通桥梁时的动力响应进行理论分析,得出轨道交通车辆过桥时共振和振动相消的公式。当桥梁第一阶竖向自振频率等于车辆速度与车辆长度之比时,会发生共振。为避免桥梁共振,设计时应满足第一阶竖向自振频率大于车辆最大速度与车辆长度的比值。当桥梁第一阶竖向自振频率等于车辆速度与两倍桥梁跨长之比的奇数倍时,轴重在桥上引起的自由振动和轴重离开桥梁后桥梁的自由振动相互抵消,桥梁振动最小。

Study on the Vibration of Rail Transit Bridge Based on Moving Load Passing Bridge

By applying vibration-mode decomposition method, the dynamic response of moving load passing rail transit bridge is theoretically analyzed. The formulas of resonance and vibration of the bridge are obtained. When the first vertical frequency of the bridge equals to the ratio of vehicle speed to the vehicle length, the resonance of the bridge occurs. To avoid the most dangerous resonance, the first vertical frequency of the bridge should be greater than the ratio of the maximum vehicle speed to the vehicle length in design. When first vertical frequency of the bridge equals to the ratio of odd times of vehicle speed to two times of the bridge span, the free vibration caused by the axle load on the bridge is counterbalanced with the free vibration of the bridge after the axle load left the bridge. The slightest vibration of the bridge occurs.