移动车辆荷载作用下大跨径连续梁桥动力响应研究

Dynamic Responses of Long Span Continuous Girder Bridges Under Action of Moving Vehicle Loads

针对移动车辆荷载作用下公路桥梁动力性能设计与评价方法不足的问题,以依兰松花江公路大桥为例,运用自编程序,分析不同车辆荷载工况下桥梁冲击系数与振动加速度等动力响应指标的变化规律。结果表明,冲击系数随车辆纵向间距与车速的变化规律一致,均呈波动上升趋势;多车道时,若桥面不平整度沿横向变化不明显则冲击系数与车道数基本无关;大跨径桥梁不同部位的冲击系数有别,现行规范所采用单一断面的冲击系数计算全桥设计荷载方法的合理性值得商榷;在固定车距下,冲击系数随着加载效率的增大而呈下降趋势;振动加速度与冲击系数具有高度相关性。本文所得结论为移动车辆荷载作用下桥梁动力性能设计与评价提供了一定的依据。

As for the drawbacks of the design and evaluation methods for the dynamic perform‐ance of highway bridges under the action of moving vehicle loads ,the Yilan Songhua River High‐way Bridge was selected as an example and the changing laws of the dynamic response indices , such as the DLA （dynamic load allowance） and vibration acceleration ,of the bridge under the dif‐ferent vehicle load cases were analyzed by the program complied by the authors in this paper .The results of the analysis demonstrate that the changing laws of the DLA are consistent with the chan‐ging of the longitudinal vehicle spacing and vehicle speed and the laws exhibit an upward trend in fluctuation .On condition of the multiple vehicle lanes ,if the roughness of the bridge deck does not change significantly in the transverse direction of the bridge ,the DLA is basically irrelevant to the numbers of the lanes .Besides ,the DLA of various positions of the long span bridge is different . The method for calculating the design load of the whole bridge ,using the DLA of the only one sec‐tion as specified in the current design code may not be reasonable enough and remains to be dis‐cussed .The DLA is found to decrease with the increase of the loading efficiency when the vehicle spacing is fixed .Also ,the vibration acceleration is proved to be highly related to the DLA .The conclusions generalized in this paper can provide certain basis for the design and evaluation of the dynamic performance of highway bridges under the action of moving vehicle loads .