基于长期监测的特重车流作用下桥梁动态放大系数研究

Analysis of bridge dynamic amplification factors under extra-heavy truck scenarios based on long-term monitoring data

基于桥梁监测系统记录的特重车交通荷载数据研究了特重车过桥的空间动力响应和动态放大系数。首先利用某高速公路大桥安装的交通信息采集系统和动态称重设备(WIM)实时采集数年的交通荷载信息形成与实际车流特征相符的随机车流样本,定义并提取特重车交通荷载工况。其次,建立公路桥梁典型车辆动力分析模型库,推导了各典型车型的质量、刚度、阻尼矩阵,并将典型车型的车辆动力分析模型嵌入到自行研发的随机车流-桥梁耦合分析软件BDANS(Bridge Dynamic Analysis System)。最后以一座6跨连续T梁桥为工程实例,计算了特重车交通荷载作用下桥梁的空间动力响应和动态放大系数,研究了动态放大系数与路面粗糙度、纵梁的横向位置以及车重的变化关系。结果表明,动态放大系数随路面粗糙度的增大而增大,随车重的增大而减小;车辆直接作用位置处的纵梁动态放大系数小于远离车辆作用位置处的纵梁;特重车交通荷载下桥梁的动态放大系数比按照规范确定的动态放大系数小。

The bridge dynamic responses and dynamic amplification factors （DAFs） under the extra heavy truck scenarios recor- ded by the bridge monitoring system are investigated. Firstly, the real traffic flow is recorded by the real-time monitoring sys- tem and weigh-in-motion system installed on a highway bridge and extra-heavy truck scenarios are defined and extracted from the database of traffic flow. Secondly, a typical vehicle database of highway bridges is then established and the matrices of mass, damping and stiffness for each typical vehicle model is formulated, then the dynamic analysis models are assembled into a self-developed bridge dynamic analysis program BDANS （Bridge Dynamic Analysis System）. Finally, a six-span T-beam con- tinuous bridge is adopted to calculate the dynamic responses and DAFs under extra-heavy truck scenarios. The influences of road surface condition, transverse location of T-beams and vehicle weight on DAFs are examined. The results show that： DAF increases with the deterioration of road surface condition while the increase of vehicle weight seems to have opposite influence. DAF for the beam directly underneath the vehicle is lower than for the beams whose location is further away from the vehicle. The DAF calculated from the real extra-heavy truck scenarios is smaller than the Chinese code specified.