双链式悬索桥在单车荷载下的振动特征

Vibration character of a double cable suspension bridge under a single vehicle load

鉴于车体点头刚度对双链式悬索桥动态响应的影响很小,采用单个移动质量-弹簧-阻尼车辆模型,应用达朗贝尔原理和位移协调条件,推导出车桥耦合振动的运动方程。考虑几何非线性及桥面平整度因素,就车辆沿桥纵轴向中心行驶和偏心行驶两种工况,探讨单个移动车辆荷载对双链悬索桥振动响应的影响。针对不同车速、不同桥面平整度,分析了单个车辆对双链式悬索桥的冲击效应。引入主缆形状系数,将单链式悬索桥作为双链式悬索桥的特例,就双链式悬索桥和单链式悬索桥车振响应进行对比分析,揭示双链式悬索桥车振特征。双链式悬索桥车振响应特征的研究对该类桥设计选型、动力性能评估及动力加固设计都有积极的意义。

Taking the fact that the stiffness of vehicle body nod has little effect on the dynamic responses of a double cable suspension bridge into account,a single moving mass-spring-damper model was adopted to simulate a vehicle.The equation of vehicle-bridge coupled vibration was derived using D'Alembert principle and the compatibility conditions of displacements.The dynamic responses of a double cable suspension bridge to a vehicle moving at different speeds were analyzed,considering the geometric nonlinearity and the bridge carriageway irregularity factor,under two types of vehicle loading conditions,namely,moving along the central longitudinal axis and the eccentric one.Then,the influence of the vehicle velocity and the bridge carriageway irregularity on the impact coefficient of the double cable suspension bridge was discussed.Single cable suspension bridge could be taken as a special case of the double cable suspension bridge,after the main cable shape coefficient was introduced.The dynamic responses of the double cable suspension bridge and the single cable suspension bridge were compared to reveal the character of vehicle vibration of the double cable suspension bridge.The study on the dynamic responses character of the double cable suspension bridge was of great significance to structural form selection of such type bridge during designing,dynamic performance evaluation and reinforcement design.