实测车辆荷载作用下桥梁位移响应及其相关性分析

Analysis of Bridge Displacement Response and Its Correlativity Under Measured Vehicle Loads

为研究实测车辆荷载作用下桥梁的位移响应,以安庆长江公路大桥为工程背景,基于参数修正方法建立有限元模型,计算得到跨中位移影响线;基于动态称重系统(WIM)及拍照系统提取车流数据,将实际车流信息施加于位移影响线,分析实测车辆荷载下桥梁跨中位移的反演值,并与GPS系统监测得到的位移值进行对比。结果表明:基于车辆荷载反演桥梁位移响应的方法能较为准确地反演出车辆过桥时主跨跨中位移值的变化情况,车辆荷载作用下桥梁跨中位移存在时滞效应,选取120s用于修正安庆长江公路大桥GPS监测值和反演值时程曲线,消除时滞效应后两者吻合较好;车辆荷载不仅引起桥梁下挠,同时造成位移响应振荡效应,且荷载越大振荡效应越明显;单车辆荷载作用下GPS监测值与反演值两者相差小于10%,多车辆荷载作用下两者相差较大。该方法可为桥梁健康监测以及GPS监测值校验提供参考。

To study the displacement response of bridge under the action of measured vehicle loads, the Anqing Changjiang River Bridge was taken as the engineering background. The finite element model of the bridge was established based on the parameter modification method to calculate the influential line of the midspan displacement. The traffic volume was estimated based on the weigh in motion system and the image collecting system. The data of traffic volume was applied to the displacement influential line to analyze the inversion value of the midspan displacement of the bridge under the action of vehicle loads, and the results were compared with the displacement value gained by GPS system. The results demonstrate that the method to test the bridge displacement response based on the inversion of vehicle loads can accurately reflect the variation of midspan displacement when vehicles passing. The time lag effect exists in the midspan displacement of the bridge under the action of vehicle loads, 120 s was selected to modify the time history curves of the GPS monitored data and the inversion data, when the time lag effect was eliminated, the time history curve of the GPS monitored data and that of the inversion data were in good agreement. Vehicle loads not only caused the deflection of bridge, but also induced shock response, and the heavier the vehicle loads, the more obvious the shock response would be. The difference between the GPS-monitored value and the inversion value under the action of individual vehicle load was smaller than 10%, but the difference was bigger under the action of multiple vehicles. The method can be used to provide reference for the check of the data from bridge health monitoring system and GPS system.