钢 混凝土简支组合箱梁桥在车辆荷载作用下的动力响应及冲击系数研究

由于钢 混凝土组合箱梁桥比同跨度的混凝土梁桥要轻，因此在车辆荷载作用下，车桥动力相互作用更加明显。为了更精确地分析其动力响应及冲击系数，采用ANSYS软件建立了钢 混凝土简支组合箱梁桥的车桥有限元模型，分析了不同车辆荷载作用下简支组合箱梁桥的动力特性；根据简支梁跨中的最大动位移与最大静位移之比，计算了不同结构参数下钢 混凝土简支组合箱梁桥的冲击系数。结果表明：在常见速度范围内，车辆过桥速度对冲击系数的影响总体呈上升趋势；对于同等跨度桥梁，双轮荷载激起的桥梁最大跨中挠度和冲击系数均比单轮荷载作用时小，但前者引起的跨中最大加速度远大于后者，且这种现象随荷载过桥速度的增大而明显。说明对于质量相对较轻的公路钢 混凝土组合箱梁桥，在冲击系数的确定中应考虑较高速度下不同车辆模型的影响。

Research on Dynamic Response and Impact Factor of Simple Steel concrete Composite Box Beam Bridges Under Vehicle Loads

Steel concrete composite box beam bridges are lighter than the concrete bridges with same span, so the vehicle bridge dynamic interaction will be more apparent. In order to analyze the dynamic response and impact factor of the steel concrete composite box beams more accurately, the vehicle bridge coupled finite models are established by ANSYS, and the basic dynamic responses are analyzed under different vehicle loads; Based on the ratio of the maximum dynamic deflection to the maximum static deflection at the middle span, the impact factors of simple steel concrete composite box beams with different structural parameters are calculated. The results show that, in normal speed range, the influence of vehicle speed on the impact factors of simple composite beams assumes a rising trend overall; For the bridges with same span, the middle span maximum dynamic deflection and impact factors induced by double wheel loads are all smaller than that under single wheel loads, but the maximum middle span acceleration induced by the former is much lager than that of the latter, and these trends are more apparent with the vehicle speed increase. The research in this paper indicates that, for the highway steel concrete composite box beam bridges which are much lighter than the concrete bridges with same span, the influence of different vehicle loads on the impact factors should be considered.