大跨度桥梁颤振及其分支跳转的发生机理研究

With the development of the international economy and communication, more and more cross-sea bridge is under-construction or will be built. When entering the new century, the construcion achivevement of long-span bridge of China is to be the focus of world attention. Among the top 10 cable supported bridge in the world, China has five places in suspension bridge, while seven places in cable stayed bridge. Innovation is to be research team's head, facing the national demand of the constructin of long-span bridge and the mission of science of wind resistant research of bridge. Flutter analysis is one of the most important research of bridge wind-resistant, and the mechanism of flutter is most important thing in bridge flutter analysis. At present, the flutter mechanism of bridge typical section is a little, and the mechanism of branch swith after flutter is particularly blank. Therefore study of the evolution of areodynamic performance of typical bridge section is very important, especially for the flutter branch swith. The project follow the analysis between theory and test, focus on the practical application of engineering. a lot of wind tunnel test of truss girder cross section, separated double box girder section, box girder and stremlined flat typical cross section should be done. Numerical simulation of the state after flutter will be made by CFD software. A new method to study the mechanism of flutter is to be establish, by which a in-depth study will be done to reveal flutter mechanism of these typical cross setion.

随着世界经济和交通事业的蓬勃发展，越来越多的跨海大桥在建或将建。进入新世纪后，我国特大桥梁建设成就举世瞩目，在全世界最大跨度前10名特大缆索承重桥中，悬索桥占5座、斜拉桥占7座，面对特大桥梁建设的国家需求和桥梁抗风研究的科学使命，研究团队开展创新工作迫在眉前。桥梁颤振是桥梁抗风的重要研究内容之一，而颤振发生机理是桥梁颤振的重中之重。目前对桥梁典型断面的颤振机理研究较少，且对其颤振后状态分支跳转的发生机理研究尤为空白。因此开展对桥梁典型断面的气动性能演化规律及其机理研究、特别颤振后状态分支跳转发生机理的研究工作尤为重要。本课题旨在遵循试验-理论分析，并着眼于实际工程应用的研究思路，拟采用实验室试验、数值模拟等手段，通过桁架主梁断面、分离双箱梁、闭口箱梁以及流线型平板等典型断面的风洞试验，并采用计算流体软件对颤振后状态的数值模拟，以建立一种新的颤振机理研究理论，对其进行较为深入的研究。

大跨度桥梁的颤振分析是抗风设计的主要依据，而风场模拟和颤振导数识别是进行颤振分析的两个前提条件。本项目在国家自然科学基金(512080155)资助下，进行了颤振分析、颤振导数识别以及风场模拟三个方面的工作。主要内容包括：研究了三种不同相干函数条件下模拟脉动风的统计特征变化规律，对比分析了三种风场模拟程序(谐波合成法、线性滤波法和特征正交分解法)的计算效率，研究结果表明：采用修正的指数表达式相干函数模拟的脉动风具有负相关性，同时能较好解决谱密度矩阵不正定的问题；谐波合成法较为适合桥梁结构的脉动风场模拟。提出了识别颤振导数的思路简单、适用性更广的小波识别法；改进了识别颤振导数的随机子空间法；编制了两种方法的计算程序，并通过算例分析验证了这些方法的有效性。发展了大跨度桥梁结构气动耦合颤振的双模态和多模态分析方法，对几座典型桥梁结构进行了耦合颤振分析，通过不同方法分析结果与精确解或试验结果之间的比较，验证了其有效性。提出了另一种修正的分步分析法，与Matsumoto提出的修正分步分析法相比，物理意义更明确；利用其对几种典型桥梁断面的颤振机理进行了深入的研究，同时首次探索性地解释了颤振后状态颤振分支跳转的原因。