中文摘要：

为充分反映列车与桥梁的动力相互作用,建立三维车辆模型及桥梁有限元模型,依据轮轨接触关系形成车桥耦合动力系统模型;考虑轨道不平顺的随机激励作用,求解车桥系统动力方程,得到桥梁节点的振动响应。在此基础上,计算桥梁构件单元的动应力响应时程。以CRH2型动车组通过某跨度为80m的下承式钢桁梁桥为例,计算分析各局部杆件的动应力时程及不同杆件的应力动力放大系数。结果表明：所给出的计算方法考虑了桥梁横向振动的影响以及轨道不平顺激励,能够真实反映列车荷载作用下桥梁局部构件的动应力响应;在列车荷载作用下下承式简支钢桁梁桥各类杆件中的危险杆件并不一定出现在桥梁跨中,动应力响应沿桥跨方向呈现出与位移响应幅值不同的空间分布趋势;不同类型杆件的应力动力系数不相同;现行规范中关于运营动力系数的计算不能真实反映不同车速下桥梁杆件应力的动力放大效应。

英文摘要：

In order to sufficiently reflect the dynamic interactions of the train and the bridge, 3D vehicle model and bridge FE model were established, and vehicle-bridge coupled dynamic system model was formed according to wheel-rail contact relationship. Considering the random excitation effects of track irregularities, the vibration response of bridge nodes was obtained by solving the dynamic equation of vehicle-bridge system, based on which, the time histories of the dynamic stress response of bridge members were computed. Taking an 80 m through steel truss girder bridge passed by the CRH2 EMU train as a case study, the dynamic stress time history of each local member and the stress dynamic amplification factors of various members were calculated. Results show that the proposed method can truly reflect the dynamic stress responses in the local members of bridge under train load by taking into account the influence of bridge lateral vibration and the excitations of track irregularities. The critical members in the simply-supported through steel truss girder bridge under train load do not necessarily appear in the bridge midspan. It is demonstrated that the dynamic stress response is spatially distributed in terms of different trends from the displacement response amplitudes in the bridge span direction. The stress dynamic factors are different for various types of the local members. The operating dynamic factor calculated according to the current codes cannot capture the dynamic amplification effects of the stresses in bridge members under various train speeds.