空间结构涡激振动分析

Vortex-induced vibration analysis of spatial structures

大跨度拱桥、空间细长杆件等空间结构在较低的风速下可能产生周期性的横风向涡激振动。本文主要讨论了空间结构涡激振动非线性稳定态,特别是共振区域的稳态响应的求解。应用Scanlan提出的经验非线性模型表达涡激力,考虑风速沿结构高度变化,引入有限元方法和条带假设形成涡激振动运动方程。利用Wilson-θ法和Newton-Raphson迭代法对运动方程计算了涡激振动振幅,同时利用能量法对运动方程进行了求解。通过对简支梁和重庆菜园坝长江大桥的分析表明,用能量法求解和按照Wilson-θ法求解的结果是一致的。

Spatial structures, such as tall buildings, long-span bridges, and slender beams may be set into periodic oscillation by cross winds of relatively low wind velocity. Nonlinear vibrations excited by vortex shedding are discussed. In particular, the steady state responses of beams near the synchronization region are taken into account. The main aerodynamic properties of wind are described by using the semi-experienced model proposed by Scanlan. The finite element method and the strip method are used to formulate the equation of motion of the system treated, considering the wind speed changed with height. The equations of motion are integrated using the Wilson-θ method and Newton-Raphson iteration method. The energy methods are also adopted to derive the amplitude equations. The results obtained by the harmonic balance method and by the Wilson-θ methods are in good agreement with each other.