列车动力荷载作用下大跨度斜拉桥局部振动响应研究

摘要

为研究列车动力荷载引起的大跨度斜拉桥主梁和桥面板局部动力响应,基于车-桥耦合动力学理论建立了列车-轨道-斜拉桥空间耦合动力学模型.采用固定界面模态综合法和等效正交异性板法建立大跨度斜拉桥精细化三维有限元模型,车辆简化为具有二系悬挂的31自由度弹簧-质量模型,轮轨关系采用可分离的三维轮轨滚动接触模型.以主跨为1 092 m的沪通长江大桥为例,研究了轨道不平顺激励条件下高速列车行驶引起的桥面板和主桁架梁的动力响应特征及分布规律.研究结果表明:固定界面模态综合法既可以有效减少模型自由度数目,又可以反映桥梁局部动力响应;等效正交异性板法虽能较好地反映桥面板的局部振动,但由于没有考虑等效前后主梁整体刚度的一致性,故所计算的主梁振动位移偏差较大;由于桥面板局部竖向刚度较小,桥梁行车线正下方的桥面板竖向加速度远大于主梁桁架节点竖向加速度,建议我国相关铁路桥梁规范在评估大跨度板桁斜拉桥振动加速度时,考虑桥面板局部振动的影响;列车动力荷载作用下主梁桁架杆件应力冲击系数较小,动力效应不显著.%In order to study the local response of main girder and steel deck induced by traveling train load in long-span cable-stayed bridge,a spatial coupling dynamic model of train,track and cable-stayed bridge was established based on the theory of vehicle-bridge coupling vibration.The fixed-interface component mode synthesis method and equivalent orthotropic plate method were employed to build the fine finite element model of long-span cable-stayed bridge,the vehicle was modeled as a mass-spring-damper system with a two-layer suspension system at 31 degrees of freedom,and the spatial roll contact between wheel and rail was used to simulate the wheel-rail contact.Hutong Yangtze river cable-stayed bridge,which the main span length is 1 092 m,was taken to study the distribution law and characteristics of vibration of bridge deck and main truss girder induced by high speed trains.It is indicated that equivalent orthotropic plate method could well reflect the local vibration of bridge deck,but the vibration displacement of main girder has certain deviation due to without considering the consistency of the overall stiffness of the main girder after the equivalence.The vertical acceleration of deck beneath the running lane is far greater than the points in main girder truss due to the smaller local vertical stiffness of deck.When evaluating the serviceability of long-span plate-truss cable-stayed bridge according to relevant codes of railway bridges,the influence of bridge deck vibration should be considered.The impact coefficient of the main girder truss bar stress is small under dynamic train loading,so the dynamic influence is not obvious.