多塔斜拉桥竖弯基频估算实用公式

Estimation Practical Vertical Bending Fundamental Frequency Formula for Vibration of Cable-Stayed Bridges with Three Towers

为方便快速计算多塔斜拉桥的竖向自振频率,有效解决多塔斜拉桥概念设计阶段有限元软件模拟的工作量较大的问题,基于最简单的多塔斜拉桥形式——三塔斜拉桥,应用Rayleigh法,求得了主梁竖向自由振动的振型函数和主塔纵向自由振动的振型函数,推导了三塔斜拉桥竖弯振动频率公式,并通过与规范解及有限元解的对比,验证了该公式的可行性.研究结果表明,给出的能量法得到的竖弯基频计算值与有限元值误差比规范解与有限元值误差小.则认为本文公式能满足斜拉桥概念设计阶段的要求,且该公式适用于三塔斜拉桥的振动基频快速估算.

In order to calculate fundamental frequency of the cable-stayed bridges with multi-tower conveniently, effectively solving the problem of the large simulation workload in conceptual design phase of multi-tower cable-stayed bridge by finite element software, based on the simplest multitower cable-stayed bridge, three-tower cable-stayed bridge, using the Rayleigh method, the vibration mode function of vertical free vibration of main girder and the free vibration mode of main tower are obtained, the formula of vertical bending vibration frequency of three-tower cable-stayed bridge is deduced, and the feasibility of the formula is verified by comparison with normal solution and finite element solution. The results show that the fundamental frequency calculated by the recommended method＇has a smaller error compared with the finite element method （FEM） result, which meets with the requirement of conceptive design. The presented theoretical formula could be applied to estimate frequency for vibration of cable-stayed bridges with three towers.