基于精细有限元法的车致大跨度斜拉桥整体及局部振动研究

为研究列车-大跨度板桁结构斜拉桥耦合振动引起的整体与局部振动响应问题,提出了基于车-桥耦合动力学的数值分析方法.首先建立桥梁结构精细化三维有限元模型,并由直接刚度法建立桥梁子系统动力方程;列车采用31自由度刚体动力学模型,轮轨之间分别采用赫兹非线性接触模型和非线性蠕滑力模型计算法向力和蠕滑力;利用自主开发软件TRBF-DYNA开展车-桥耦合系统加速度、动位移以及动应力分析.以主跨406m的三塔斜拉桥荆岳铁路洞庭湖大桥为研究对象,开展了不同行车线路、不同车速以及不同轨道不平顺条件下的耦合系统动力响应分析,研究了桥梁整体和局部动力响应,以及列车运行安全性指标和乘坐舒适性指标的变化规律.结果表明:正交异性钢桥面板的局部动力响应远大于钢桁架主梁;大跨度斜拉桥的动力系数较小,受车速和轨道不平顺谱的影响较小;钢桁架主梁下弦杆和腹杆处于高周疲劳应力工作状态,在疲劳性能研究中需要特别关注;设计速度条件下,桥梁动力响应指标以及列车运行安全性和舒适性指标均满足规范要求.

Research on Global and Local Vibration of Long-span Cable-stayedBridge Induced by Passing Train Based on FineFinite Element Method

To investigate the global and local dynamic response of plate-truss composite structure (i.e.,cable-stayed bridge induced by train-bridge coupling vibration),a numerical approach was presented based on train-bridge coupled dynamics. A coupled train-bridge system model composed of a 3D vehicle model with 31 degrees of freedom,a 3D fine bridge model established by the direct stiffness method,and an assumed wheel-rail spatial contact relationship based on the Hertz nonlinear contact model and nonlinear creep force model were developed. The self-developed software TRBF-DYNA was applied to analyze the dynamic responses,such as acceleration,displacements and stresses. The Dongting Lake three tower cable-stayed bridge with a main span of 406 m in Jingyue railway line was taken as an example. The global and local dynamic response of the bridge,variations of running safety,and ride comfort index were discussed under different routes,speeds and track irregularities conditions. The results show that the local dynamic response of orthotropic steel bridge deck is much larger than the response of steel truss girder. Dynamic coefficient of large-span cable-stayed bridge is small,and the influence of the speeds and track irregularity on dynamic coefficient of large-span cable-stayed bridge is insignificant. The lower chord and web members of steel truss girder are in high cycle fatigue stress state,which should be paid more attention in the study of their fatigue properties. Further,the dynamic response of bridge,running safety indexes and ride comfort index satisfy the code requirements under the designed running speed.