随机车流作用的公路斜拉桥振动响应分析

Vibration Response Analysis of Highway Cable-Stayed Bridge under Stochastic Traffic Flow

目的分析随机车流荷载对公路斜拉桥振动响应的影响,探究斜拉桥纵梁、桥塔和斜拉索的振动响应规律。方法基于某高速公路的动态称重系统实测数据,建立考虑车型、车道、车速、车体质量、车辆间距和桥面不平顺的随机车流模型;采用MATLAB软件编程求解公路斜拉桥在随机车流荷载作用下的振动响应。结果采用蒙特卡洛法随机抽样生成的随机车流模型能真实再现桥面交通流状况,斜拉桥纵梁、桥塔和斜拉索的振动响应随着车流密度的增大而增大,每一辆重载车过桥都会激起一个桥梁振动响应峰值;纵梁应力循环次数随着车流密度的增大而增大;桥塔纵向位移响应随着桥塔高度的增加而增大;斜拉索的轴向振动响应大于面内振动响应,而面外振动响应最小;轴向振动响应随着斜拉索长度的增加而增大,面内振动响应因拉索长度不同而波动较大;斜拉桥的振动响应随着桥面路况的恶化而增大。结论重型车的限载和桥面的定期保养可以有效减小桥梁八车致的振动响应。

This paper analyzed the influence of random traffic load on the vibration response of highway cable-stayed bridge,and explored the vibration response law of longitudinal beam,tower and stay cable of cable-stayed bridge.Based on the measured data of a highway dynamic weighing system,a stochastic traffic flow model considering vehicle type,lane,speed,vehicle weight,vehicle spacing and uneven deck was established.The vibration response of highway cable-stayed bridge under stochastic traffic load was solved by MATLAB software programming.The stochastic traffic flow model generated by Monte Carlo random sampling can reproduce the real traffic situation of bridge.The vibration response of longitudinal beam,pylon and stay cable of cable-stayed bridge increases with the increase of traffic density,and each heavy-duty vehicle passing through the bridge will arouse a peak value of bridge vibration response.The number of longitudinal stress cycles increases with the increase of traffic density,and the longitudinal displacement response of bridge tower increases with the increase of tower height.The axial vibration response of the stay cable is greater than that of the in-plane vibration,while the out of plane vibration response is the smallest.The axial vibration response increases with the increase of the cable length,and the in-plane vibration response fluctuates greatly with the length of the cable.The vibration response of cable-stayed bridge increases with the deterioration of road condition.The limited load of heavy vehicles and regular maintenance of bridge deck can effectively reduce the excessive vibration response of bridge.