大跨度桥梁抗风技术挑战与基础研究

Wind resistance challenges and fundamental research on long-span bridges

以我国30年大跨度桥梁的快速发展为研究背景,对3种大跨度桥梁的抗风技术挑战进行了基础性研究和应用性研究,着重探讨了悬索桥的颤振性能及其控制、斜拉桥风振性能与拉索风雨振控制、拱式桥涡激共振及其控制、特大桥梁风振精细化理论等一系列抗风关键问题。研究结果表明:悬索桥的颤振稳定性跨径上限约为1 500 m,超过甚至接近这一上限时,必须采取措施改善加劲梁的抗风稳定性;千米级大跨度斜拉桥仍具有足够高的颤振临界风速,其主要抗风问题是长拉索的风雨振动;大跨径拱桥除了个别有涡振问题之外,还没有受到结构抗风性能的影响。文章还提出了三维桥梁颤振精确分析的全模态方法、任意斜风作用下桥梁抖振频域分析方法、基于二阶矩理论和首次超越理论的桥梁颤振和抖振可靠性评价方法,揭示了桥梁颤振演化规律、驱动机理和控制原理。

With the rapid development of long span bridges in China,this paper focused on some engineering projects related to wind resistance challenges on three types of long span bridges,including flutter instability and control of suspension bridges,wind induced vibration of cable-stayed bridges and control of wind-rain induced cable vibration,vortex shedding vibration and control of arch bridges,and the refinements on aerodynamic flutterand buffeting of super long span bridges.It can be concluded that the intrinsic limit of span length due to aerodynamic stability is about 1 500 m for a traditional suspension bridge,and beyond or even approaching this limit,designers should be prepared to improve aerodynamic stability.The long-span cable-stayed bridges with a 1 000 m main span have high enough critical flutter speed,but the main aerodynamic concern is rain-wind induced vibration of long stay cables.Except one example of vortex-induced vibration,long-span arch bridges have no wind resistance problems.The fundamental research on wind resistance of long-span bridges was also introduced with the full-mode flutter analysis method as 3D bridge flutter precise analysis,the bridge buffeting frequency-domain analysis under skew wind action,the bridge flutter and buffeting reliability evaluation method based on second order theory and first passage theory,and the unveiling of bridge flutter evoluation process,generation mechanism and control law.