中文摘要：

建立了“列车．桥梁．撞击荷载”系统动力分析模型，通过在松花江大桥进行的现场试验，得到了流冰撞击力时程，施加到桥墩上作为系统的激励。编制了分析程序，以高速铁路5x32m预应力混凝土简支单线箱梁桥为算例，通过计算机模拟，对流冰撞击作用下桥梁结构的动力响应及桥上高速列车的运行安全问题进行了研究。分析了在有流冰、无流冰撞击作用两种情况下，桥梁结构关键部位的位移和加速度响应，以及桥上高速运行列车的车辆脱轨系数和轮重减载率等行车安全指标。计算结果表明：流冰撞击作用对桥梁结构以及高速列车的动力特性具有较大的影响，撞击作用使桥梁和车辆的动力响应大幅度增大。当流冰撞击荷载峰值达到4000kN时，车辆减载率已经超过了0．6的限值。撞击荷载作为一项特殊的作用力，在高速铁路桥梁的动力设计中应予以重视。

英文摘要：

A dynamic analysis model is established for a train-bridge system subjected to a collision-load. The time history curve of a floating-ice collision load is obtained by the site experiment at the Songhua River Bridge, and it is taken as an excitation load on the bridge piers. A computer code is programed. By taking a 5x32 m simply-supported single-track high-speed railway bridge with PC box girders as a case study, the dynamic responses of railway bridges subjected to a floating-ice collision and their influences on the running safety of high-speed trains are analyzed. The whole time periods of a high-speed train running on the bridge are simulated under two conditions with and without floating ice-sheet striking on the bridge piers, from which the dynamic responses such as displacements and accelerations of the bridge, and the running safety indices such as derailment factors and offload factors of the train vehicles are investigated. The results show that the collision of floating ice has an obvious effect on the dynamic responses of the bridge and the train vehicle. The collision action obviously increases the dynamic responses of the bridge and the running vehicles. When the peak of the ice collision load reaches to 4000 kN, the offload factor of a running vehicle has exceeded 0.6, the allowance value in the Chinese code. The collision load should be treated as an important force considered in the dynamic design of high-speed railway bridges.