Abstract: The non-linear Hertz contact theory was adopted and then linearized，and a new vehicle-bridge interaction element considering the transient jump of wheel was derived，which solved the deficiency of the no-jump assumption in the traditional analysis． The dynamic equations of the interaction system were then formulated by means of the“set-in-right-position”rule for formulating matrices，and the combination method and the solution procedure were also presented． Finally the corresponding calculation program was coded，and the proposed interaction element was adopted to analyze an established railway bridge． The results demonstrate that the dynamic acceleration response of the bridge significantly increase and the results of moving loads model are safer under the vehicle-bridge resonance． The abrupt irregularity causes strongly high frequency vibration and makes the dynamic acceleration response of bridge remarkably increase． When there is no jump of the wheel， the result from the proposed method is consistent to the traditional one． But when the jump happens，the proposed method also yields a true result while the traditional one can’t，and the transient jump of wheel has been accurately simulated by the proposed method． The model considering transient jump of wheel should be adopted to analyze the vehicle-bridge interaction and the track maintenance and the deformation control of bridge should be paid more attention．

Key words: bridge engineering, vehicle-bridge interaction element, transient jump of wheel, Hertz elasticity contact, vehicle- bridge resonance, dynamic analysis

摘要： 采用非线性Hertz 接触理论，并将其线性化，推导了考虑车轮瞬时脱离的车-桥耦合分析单元，解决了传统分析 中“车轮密贴”假设的不足; 应用形成矩阵的“对号入座”法则建立了耦合系统动力方程，并给出了其组装和求解思 路; 编制了相应计算程序，对现有铁路桥梁进行了分析。结果表明: 车桥共振时，桥梁动力响应会显著增大，而移动 力模型结果更偏于安全，脉冲型不平顺会激起强烈的高频振动，使桥梁加速度响应显著增加; 未发生脱离时，考虑和 不考虑脱离模型所得结果一样，而发生脱离时，后者结果将不准确，而前者准确模拟出了脱离现象; 应采用考虑车轮 脱离的模型进行车-桥耦合振动分析，同时应重视线路养护维修和桥梁变形控制。

关键词: 桥梁工程, 车-桥耦合单元, 车轮瞬时脱离, Hertz 接触, 车-桥共振, 动力分析