双层公路钢桁梁桥车桥耦合振动

为研究车桥耦合振动对双层公路钢桁桥冲击效应的影响, 基于分离法, 以车轮与桥面接触点为界, 将车桥耦合振动系统分为车辆与桥梁2个子系统, 分别采用虚功原理与有限元法建立各自的运动方程, 并通过车轮与桥面接触处的位移协调条件及车桥相互作用力的平衡关系相联系, 采用迭代法求解系统响应。以某双层公路简支钢桁梁桥为研究对象, 应用ANSYS软件建立三维梁格有限元模型, 分析了车速、桥梁阻尼、桥面平整度及不同加载模式对车桥耦合振动的影响。研究结果表明: 车速与双层钢桁梁桥冲击系数之间没有规律性的函数关系; 桥梁阻尼增大, 能使钢桁桥杆件内力、位移冲击系数适当降低; 桥面平整度是车桥耦合振动的一个重要激励, 桥面状况越差则车辆振动越强烈, 对桥梁的整体和局部产生的冲击作用越大; 单双层加载模式的不同对桥梁整体的动力响应改变不大, 但是对局部动力响应的影响比较明显, 应在桥梁设计时考虑局部冲击效应的影响。

Vehicle-bridge coupled vibration of highway double-deck steel truss bridge

In order to study the impact effect of vehicle-bridge coupled vibration on highway double-deck steel truss bridge, contact point between wheel and bridge surface was regarded as fringe, vehicle-bridge coupled vibration system was divided into vehicle subsystem and bridge subsystem based on separation method. The motion equations of vehicle subsystem and bridge subsystem were established respectively by using virtual work principle and finite element method. Vehicle subsystem was connected with bridge subsystem through displacement coordination condition and the balance relation of vehicle-bridge interaction at contact point between wheel and bridge surface, and system response was obtained by using iterative method. A highway double-deck simply-supported steel truss bridge was taken as study case, 3D beam grillage finite element model was established by using ANSYS software, and the influences of vehicle speed, bridge damping, bridge surface roughness and different loading modes on vehicle-bridge coupled vibration were studied. Analysis result indicates that there is not very regular function relation between vehicle speed and the impact factor of highway double-deck steel truss bridge. The impact factors of internal force and displacement for all bars become smaller with the increase of bridge damping. Bridge surface roughness is an important incentive for vehicle-bridge coupled vibration, poor bridge surface can make vehicle vibration more intense, and can induce greater impact effect on the whole and part of bridge. When loading modes of single layer and double-layer are different, the whole dynamic responses of bridge change little, the local dynamic responses of bridge are more obvious, so local impact effect should be considered in the design of bridge.