Abstract: Seismic response of superstructure would appear eoupling phenomenon in curve bridge.This phenomenon mainly includes transverse displacement and in·plane rotation.The rotation mechanism of earthquake action in chord direction is re- searched. Based on the analysis on the simplified single-span curve bridge and linear time-history，the in-plane rotation mechanism of curve bridge is studied，and different seismic responses with different curvature ratio are compared.The efect of the girder-abutment interaction on the in-plane rotation is discussed.Nonlinear time-history method is applied to calculate the seismic response with diferent curvature and diferent input direction.Finally，the most adverse input angle of earth- quake is determined.

Key words: cun, e bridge；seismic response；in-plane rotation；earthquake input angle

摘要： 曲线桥梁在水平地震作用下，上部结构在两个主方向上的地震反应会产生耦合现象，该现象主要为梁端的横 向位移和桥面板的面内转动；通过对简化的单跨曲线桥模型进行弹性时程分析，研究曲线桥在弦线方向的地震输入 下的转动机理，并比较不同曲率半径下曲线桥的地震反应；讨论主梁一桥台相互作用对桥面板转动的影响，应用非 线性时程分析计算不同曲率的曲线桥在不同地震输入角度下的地震反应，并确定最不利地震输入角度。

关键词: 曲线桥, 地震反应, 面内转动, 地震输入角度