大跨度桁梁桥主梁的气动力特性研究

Today, the long-span steel truss girder bridge has got widely applications in China's bridge construction. For the study on truss girder bridge wind resistance, though there has been some progress made in its aerodynamic behavior, the core problems such as lacking systemic reasarches and using an incomplete theoretical system still need to be settled. Therefore, there is vast space to be developed and much more investigations need to be done in this field in order to help people get a more profound understanding of the aerodyanmic characteristics about long-span steel truss girders. These investigaions include the matters as following: the girder aerodynamic parameters influenced by the relative position between deck and truss, by skew wind,by structure pattern(2 main trusses or 3 main trusses) and by the size; the mechanism of truss girder flutter; the spatial correlation of truss girder's aerodynamic forces; the nonlinear aerodyanmic characteristics of truss grider and its corresponding nonlinear resopons etc. This application herein is going to focus on typical steel truss girders of long-span highway bridges, railway bridges and highway-railway bridges. By employing theoretical analysis, wind tunnel model test and computational fluid dynamics simulation, we will make a detailed study of the girders' aerodyanmic forces under skw wind, the flow field characteristics around the truss, the mechanism of torsional flutter, the expression of aerodynamic parameters and the influence of aerodynamic measures. As a result, the characteristics of aerodynamic forces and its relative correlation for typical truss girders can be obtained, as well as the expression of aerodynamic admittance, both of which may further improve the existing theroy and develop the design practice on truss girder bridge wind resistance.

大跨度钢桁主梁桥在我国已得到大量的应用，桁架主梁的气动力性能研究虽也取得了一些进展，但其仍缺乏系统性且理论体系也不完善，因而，对于大跨度钢桁主梁气动力特性的问题仍有很大的发展空间及需要进一步研究的内容。包括公路或铁路桥面与主桁的相对关系对主梁气动参数的影响，桁架梁扭转颤振发振机理，风偏角对主梁气动力参数的影响，桁梁的结构参数（两片或叁片桁）、尺寸参数等对气动力特性的影响，桁梁的气动力空间相关性，桁梁的非线性气动力特性及其非线性响应性能等等。本申请书拟结合大跨度公路、铁路或公铁两用三类桥梁的典型桁式主梁采用风洞模型测压试验、风洞模型测力试验、计算流体动力学模拟、理论分析等手段对其在不同风向角下气动力特性、气动绕流特性、扭转颤振机理、气动参数表达式及气动措施影响机理等进行研究，确定典型桁梁的气动力特征及其相关性、气动导纳及其表达式等，进而完善桁梁桥的抗风设计与分析理论。

大跨度钢桁主梁桥在我国已得到大量的应用，桁架主梁的气动力特性的描述仍缺乏系统性，相关抗风分析理论体系也不完善，针对钢桁主梁气动力特性研究具有重要的理论意义。采用风洞模型试验、计算流体动力学模拟、理论分析等手段，对大跨度桥梁桁式主梁的风荷载及气动绕流特性进行研究。.基于双移动动态天平测量的风洞模型试验，建立了典型桁梁气动力及其相关性表达式；基于计算流体动力学CFD数值计算，探明了典型桁梁气动力绕流特征和桁片间风载分配与桁梁结构参数的关系；基于动态天平测量的风洞模型试验，建立了典型桁梁结构的气动导纳表达式；采用专门研制的装置及静力天平，通过风洞模型试验研究，明确了桁梁气动力参数与风向角的关系；明确了气动措施对桁梁气动性能的影响机理等；根据理论推导和数值分析，建立了主梁涡振与颤振可靠度的计算方法；建立了一种考虑桥梁大振幅非线性颤振分析方法。研究成果可直接应用于实际工程，对于完善大跨度桁梁桥的抗风设计与分析理论具有明显的意义。