中文摘要：

悬索桥的振动性状中呈现纵飘振动与竖向反对称低阶振动相互耦合的特点。基于挠度理论和能量原理,研究了耦合自振的频率计算方法。首先把加劲梁的单纯纵飘看作单摆振动,得出其等代摆长和振动频率。再结合主缆的竖向反对称低阶振型下的纵向位移特点,建立考虑主缆纵向位移影响的加劲梁纵飘振动的简化计算模型,获得其势能增量的简单表达式。由哈密顿原理,推演了耦合振动频率的计算方法。通过5座桥梁实例验证,利用该文公式获得的耦合频率和振型形状判定与有限元计算结果吻合良好,表明该文提出的计算方法实用可靠。

英文摘要：

Significant coupling between the longitudinal modes with the lower anti-symmetric vertical modes was observed in vibration of suspension bridges.Based on the deflection theory and energy principle,this type of coupling vibration was investigated.First,by assuming the suspended structures as a simple pendulum,the pure longitudinal vibration analyses were carried out to determine the length of equivalent pendulum and the frequency.Then,according to the features of the longitudinal motion associated with the lower vertical modes of the cable,a simplified model was established for stiffening girder longitudinal vibration,in which the effect of the cable motion was taken into account.From Hamilton＇s Principle,the formula for coupling vibration frequencies was theoretically derived.Finally,investigations on five specific bridge examples indicate that the calculated coupling frequencies and mode shapes were in good agreement with those predicted by finite element method.