基于长期监测的车-桥共振分析

以沪昆下行线湘潭湘江特大桥长期监测数据为基础,研究了桥梁应力、振动与客车通行速度的相关性,重点分析了特定速度下的车-桥共振特性。研究结果表明:桥梁横向和竖向均存在明显的共振现象;应力幅值与客车通行速度散点图为单峰形状,客车运行速度在20~40 km/h时应力幅值较大;动力系数随运行速度的增加而增大,但小于安全限值;客车运行速度为35 km/h和50 km/h时,客车的激励频率与桥梁横向1阶自振频率接近,桥梁易发生横向共振,导致桥梁横向振动响应较大,竖向振动幅值随列车运行速度的增加而增大;当客车以25 km/h通过桥梁时,客车激励频率与竖向1阶自振频率接近,桥梁易发生竖向共振,但其竖向振动不明显,应力响应较为显著。建议车辆应尽量避开以上速度通过该桥。

Vehicle-Bridge Resonance Analysis Based on Long-term Monitoring

Based on the long-term monitoring data of Xiangtan Xiangjiang large bridge on Shanghai-Kunming down line,the correlations of bridge stress and vibration with train speed were studied,the vehicle-bridge resonance characteristics at specif ic speed were emphatically analyzed.The analysis results show that there are obvious resonance phenomena in the transverse and vertical of the bridge.The scatter plot of stress amplitude and train speed is a single peak shape,and the stress amplitude is larger when the train speed is 20~40 km/h.The dynamic coeff icient increases with the increase of train speed,but is less than the safety limit. W hen the train speed is 35 km/h and 50 km/h,the excitation frequency of train is close to the f irst-order transverse natural frequency of bridge,and the bridge is prone to transverse resonance,which results in large transverse vibration response of bridge,and the amplitude of vertical vibration increases with the increase of train speed. W hen the train passes through the bridge at 25 km/h,the excitation frequency of train is close to the f irst-order transverse natural frequency of bridge,and the bridge is prone to vertical resonance,but its vertical vibration is not obvious,and the stress response is more signif icant .It is suggested that trains should avoid the above speeds as far as possible to pass through the bridge.