我国是世界上少数几个受风灾影响最严重的国家之一，强风引起的极值风荷载往往成为控制桥梁设计和施工的关键因素。为了改善气动性能，桥梁抗风研究中往往需要花费大量人力物力和时间来寻找有效的风振控制措施，而其根本原因是原始桥梁构件在空气动力性能方面的某种“缺陷”。如能在掌握风振机理、特别是结构绕流流态特征同风振性能内在联系的基础上实现桥梁构件的气动外形优化，就能有效提升抗风研究的水平和效率。基于这一研究思路，项目采用以粒子图像测速技术为主、数值模拟为辅的流场定量可视化技术，从桥梁风振现象的内在机理分析理论出发，建立宏观和细观层面相结合的桥梁构件抗风性能优化方法，实现主动地对可能应用于超大跨度桥梁的扁平闭口箱梁和分体箱梁进行气动性能外形优化，并针对关键外形参数的抗风性能参数化分析和评级，满足不同层面的桥梁抗风需求。研究成果将突破和完善现有的桥梁抗风研究基础理论，对大跨度桥梁建设也能提供重要的技术支撑。

China is one of the few countries in the world, which are severely affected by wind hazards and disasters. Extreme wind loads caused by strong wind often become the key factor in bridge designing and construction. In order to improve aerodynamic performance, it usually takes a lot of effort and time to find effective control measures for wind-induced vibrations. However, the fundamental reason for this is the fact that the original bridge component has certain defects in the aspect of aerodynamic performance. If the aerodynamic configuration optimization of bridge components can be realized based on the clarification of mechanism for various wind-induced vibrations, especially the flow patterns around structures that intrinsically linked to structural aerodynamic performance, the level and efficiency of wind-resistant study can be effectively improved. Based on this idea, aerodynamic configuration optimization method for bridge components in the aspect of aerodynamic performance, which has a combination of both macro and micro levels, will be established in this project, through theoretical analysis on the inherent mechanism of wind-induced vibrations for bridges, with the help of quantitative flow field visualization technique featured in Particle Image Velocimetry and supplemented by numerical simulation. With this method, the aerodynamic configuration of closed box girder and twin box girder, which may become the potential candidates to be applied to super long-span bridges, will and can be initiatively optimized based on aerodynamic performance. And the parametric analysis and ratings for the structural wind-resistant performance induced by different sets of critical shape parameters will also be conducted to meet with the service requirements of different levels. The expected research results in this project will be a substantial improvement and breakthrough to wind-resistant fundamental theories for bridges, and provide a solid technical support to the constructions of long-span bridges.