为适应高速铁路的快速发展，有必要深入分析地震作用下的桥梁动力响应．文中基于有限元软件建立了圆端型墩高速铁路多跨简支梁桥体系的全桥模型，分析了结构的自振特性，分别输入不同车速、强震记录、墩高、地震强度以及不同方向地震作用组合等工况，计算了车桥系统的弹性地震响应; 并通过赋予非线性梁单元弯矩–曲率关系，计算了有车/无车工况下圆端型桥墩的弹塑性地震反应．计算结果表明，设计地震作用下桥梁结构处于弹性状态，随着车速、墩高的增加，桥梁的地震响应呈上升趋势; 罕遇地震作用下墩底进入弹塑性状态，列车荷载对桥墩地震响应影响较小，墩底形成塑性铰，需采取措施以
保证墩底塑性铰区的安全．

As the high-speed railway is developing rapidly both in China and abroad at present,it is necessary to deeply analyze the dynamic responses of high-speed railway bridges under seismic action. In this paper,a wholebridge model of a multi-span simply-supported high-speed railway bridge with round-ended piers is set up with the finite element software,and the natural vibration properties of the structure are analyzed. Then,different speeds,strong motion records,pier heights,earthquake accelerations and earthquake load combinations in various directions are respectively input to calculate the elastic seismic responses of the bridge. Finally,by applying the moment-curvature relationship to the nonlinear beam element,the elastoplastic seismic responses of the round-ended piers with and without train loads are calculated. The results show that,under the designed earthquake,the bridge is in the elastic stage and the seismic responses increase with the train speed and pier height,while under severe
earthquakes,the pier bottom steps into the elastoplastic stage,the impact of train loads on the seismic responses of the round-ended piers is relatively slight,and plastic hinges occur at the pier bottom,so that some countermeasures should be taken to ensure the security of the plastic hinge region.