列车制动和运行下大跨度公铁两用斜拉桥纵向振动分析

摘要

The vibration response of the cable-stayed bridge under train running occurs in vertical and longitudinal direction.When the train brakes on the bridge, the braking forces acting on the structure lead to the longitudinal vibration response of the cable-stayed bridge.Based on a rail-cum-road cable-stayed bridge, the train braking forces were obtained by calculation formulas in relevant literature.The dynamic response of the bridge induced by train braking was investigated.Train running was simulated using moving loads to study the train-induced dynamic response of the bridge.The parameter sensitivity study of viscous dampers was performed through nonlinear dynamic time history analysis.The effect of viscous dampers on mitigating the longitudinal vibration response of the bridge under train braking and running was investigated.The response of the bridge with viscous dampers was compared with that of the bridge without viscous dampers.The results showed that the response of the cable-stayed bridge without longitudinal deck-tower connection under train running was affected significantly by the train speed, in which case, the longitudinal resonance for the cable-stayed bridge may occur and the response of the bridge increases significantly.Viscous dampers installed between the deck and the tower can effectively reduce the longitudinal vibration response of the cable-stayed bridge induced by train braking and running.%列车运行作用下斜拉桥不仅发生竖向振动,也发生纵向振动;当列车在斜拉桥上制动时,作用于结构上的制动力使其发生纵向振动.以公铁两用斜拉桥为研究背景,根据相关文献计算公式获得列车制动力,分析列车制动作用下斜拉桥动力响应;采用移动荷载模拟列车运行作用,研究列车运行作用下结构动力响应;利用非线性动力时程分析方法,对黏滞阻尼器参数进行敏感性分析,探讨塔梁间设置黏滞阻尼器对列车制动和运行作用下结构动力响应的影响,并与未设置黏滞阻尼器的情况进行比较.结果表明,当斜拉桥塔梁间无纵向连接时,结构响应受列车运行速度影响较大,斜拉桥可能发生纵向共振,结构响应显著增大;塔梁间设置黏滞阻尼器能有效控制列车制动和运行作用下斜拉桥纵向振动响应.