并列相邻桥梁气动干扰对车桥耦合振动的影响研究

Influence of aerodynamic interference of parallel adjacent bridges on coupled vibration of train-bridge system

公铁两用桥梁主要有公铁合建和公铁分建双梁2种形式,公铁分建形式以安全隐患小、运营维护方便的原因被广泛应用。采用公铁分建形式时,并列相邻桥梁之间的气动干扰导致其周围流场与单铁路桥梁周围流场不同,横风作用下车桥耦合振动响应也较单铁路桥梁不同。为研究并列相邻桥梁气动干扰对车桥耦合振动的影响,以某公铁分建形式斜拉桥为研究对象,通过数值模拟获得并列主梁和单主梁下的车桥系统三分力系数,进行风洞试验并验证了数值模拟的合理性和准确性,根据弹性系统动力学总势能不变值原理对并列主梁和单主梁形式分别建立风-车-桥耦合振动仿真计算与分析模型,计算了2种形式下车桥耦合振动响应。研究结果表明:铁路梁位于背风侧时,与单铁路梁相比,铁路梁阻力系数减小,升力系数与扭矩系数增大,列车阻力系数及扭矩系数增大,升力系数减小,列车通过桥梁时的桥梁横向位移及列车动力响应显著增大,桥梁竖向位移基本不变;铁路梁位于迎风侧时,与单铁路梁相比,桥梁与列车三分力系数变化不明显,列车通过桥梁时的桥梁与列车动力响应变化不大。铁路梁位于背风侧且环境风速越大时,并列桥梁的气动干扰效应对车桥耦合振动动力响应的影响不容忽略。

There are two types of rail-cum-road bridges:railroad combined and railroad separated.Construction of railroad separated bridges is recommended due to their reduced potential safety hazards and ease of maintenance.In the case of separate construction,the aerodynamic interaction between parallel adjacent bridges results in a distinct flow field compared to that around a single railway bridge.In addition,the coupled vibration responses of the train and bridge under crosswind are also altered.To investigate the effects of aerodynamic interference between parallel adjacent bridges on the coupled vibration of train-bridge systems,we conducted a numerical simulation on a cable-stayed bridge built for both highway and railway.This involved calculating the three component coefficients of the train-bridge system both under parallel bridges and a single bridge.These numerical results were then compared to experimental data to verify the accuracy and suitability of the simulation method.The models for vibration coupling between train and bridge were established for single and parallel bridges based on the principle of total potential energy with stationary values in elastic system dynamics.The responses of the train-bridge system were assessed in two forms.Results indicate that in comparison to a single railway bridge,when the wind blows from the opposite direction,the drag coefficient of a railway bridge decreases while the lift and torque coefficients increase.The drag and torque coefficients of the train increase while the lift coefficient decreases.Further,when the train passes,both the lateral displacement of the bridge and the responses of the train increase substantially,while the vertical displacement of the bridge remains unchanged.On the windward side,the railway bridge shows no significant change in the three component coefficients compared to a single railway bridge.When a train passes,there is little change in the responses of both the bridge and the train.However,if the railway bridge is on the leeward side and the ambient wind speed is high,the effects of aerodynamic interference cannot be overlooked.