桥梁主梁断面气动耦合颤振分析与颤振机理研究

Aerodynamically coupling flutter analysis and flutter mechanism for bridge deck sections

通过对系统竖向和扭转耦合振动运动方程的解耦,将系统振动参数的频率和阻尼比隐式地表达成桥梁断面颤振导数的函数形式,导出了二自由度耦合颤振分析方法。值得注意的是,在临界颤振的情况下颤振运动为等幅的谐波运动,因而在颤振临界点时该颤振分析方法理论上是完全精确的。将该分析方法的结果与系统特征值分析方法的计算结果进行比较,验证了该分析方法的可靠性和适用性。在此基础上,对典型桥梁断面气动耦合颤振的机理进行了研究。分析结果表明,对于典型扁平箱形桥梁断面来说,耦合颤振导数项对系统振动参数中频率的影响均较小,系统模态的气动阻尼比主要由直接颤振导数项和耦合颤振导数项A1A3构成。

A 2DOF coupling flutter analysis is presented based on an uncoupling of torsional and vertical coupled motion equations of system, in which the frequencies and damping ratios of the system vibration characteristics are expressed implicitly as functions of flutter derivatives. It has been noted that the results of the presented method at the critical flutter state is theoretically exact since the critical flutter motion is constant-amplitude and periodically. The comparison of the results with the exact ones by a characteristic analysis of system motion equations is performed so the reliability and applicability of the presented method is proved. Moreover, the mechanism of aerodynamically coupling flutter for a typical bridge deck section is investigated. It is noted that the effect of the coupling flutter derivatives on the frequency of the system modes is small and the aerodynamic damping is mainly made up of the terms of direct flutter derivatives and A1^＊A3^＊.