大跨桥梁颤振分析理论研究进展

随着悬索桥跨径朝向2 000 m级发展,由大攻角和大振幅引起的结构非线性和气动力非线性影响突出,颤振设计面临着前所未有的挑战。传统的桥梁颤振计算理论及方法已无法满足大跨度及超大跨度桥梁的抗风设计需求,亟需发展桥梁非线性颤振计算理论与方法。在扼要回顾线性颤振理论研究成果的基础上,对近年国内外关于桥梁非线性颤振的研究进展及主要成果进行了总结,介绍了非线性自激气动力的研究成果和几种典型的非线性自激气动力模型,并根据桥梁断面气动力随振幅变化的非线性特性,重点介绍了2种不同类型的非线性耦合颤振计算方法,其有效性和准确性均通过风洞试验进行了验证。需要指出的是,气动力的振幅依存性是大跨度桥梁颤振后状态研究的关键所在,尤其是计入耦合效应的高次谐波气动力的振幅依存性。基于目前的研究进展,确定了三维和多模态非线性颤振计算方法,任意运动及紊流下非线性气动力建模和非线性颤抖振理论,以及如何科学制定"软颤振"的评价标准是未来需要重点开展的几项工作。

Advance on Flutter Analytical Theory of Long Span Bridges

As the main span of suspension bridge increasing to over 2 000 m, the flutter design faces unprecedented challenges due to the aerodynamic and structural nonlinearities caused by large vibration amplitude and angle of attack. The current flutter analysis theory cannot satisfy the requirements of the wind-resistance design of super-long span bridges, and thus it should rapidly move toward incorporating nonlinearity. In this paper, the state-of-the-art for the linear flutter analytical theory and nonlinear flutter analytical method was firstly reviewed, and then the achievements of nonlinear self-excited aerodynamic force and its mathematical models were introduced. The particular attention was paid to two nonlinear coupled flutter analytical methods, whose validity and accuracy were verified by wind tunnel tests, according to the nonlinear characteristics of the amplitude-dependence of aerodynamic force. It should be mentioned that the amplitude-dependence of self-excited forces, especial for their higher harmonic components as considering coupling effects, is one of the most important key factors for post-flutter analysis of super-long span bridges. Three main aspects for the future studies should be focused on:the three-dimensional and multi-modal nonlinear flutter analysis, the model of self-excited forces with consideration of turbulence and ambition motion, and the reasonable evaluation criterion for soft-flutter.