大跨度悬索桥颤振的三维精细化分析

3D refined flutter analysis of long-span suspension bridges

随着悬索桥跨径的增大,静风作用、缆索上的风荷载以及风速空间分布的非均匀性都随之明显增强,可能会对大跨度悬索桥的颤振稳定性构成不容忽视的影响。在线性颤振分析方法基础上,进一步考虑静风效应、风速空间非均匀分布和主缆气动力作用等因素建立了精细化的大跨度桥梁三维非线性颤振分析方法,并编制了相应的计算分析程序。以润扬长江大桥南汊悬索桥为例,通过精细化分析揭示了静风效应、风速空间分布非均匀性以及主缆气动力等因素对大跨度悬索桥颤振稳定性影响的规律和程度。结果表明:静风作用引起的结构动力特性尤其是空气力非线性变化、风速空间非对称性分布和主缆气动力等因素对大跨度悬索桥颤振稳定性的影响显著,必须在颤振分析予以准确考虑。

With the increase of span length of suspension bridges,the static wind action,the aerodynamic load acting on main cables and the spatial non-uniformity of wind speed increase consequently,which may have an unnegligible influence on the flutter stability of long-span suspension bridges.Based on the linear flutter analysis,a refined three-dimensional nonlinear flutter analytical method was presented in which the effects of the static wind action,spatial non-uniformity of wind speed and aerodynamic load acting on main cables were further considered,and the corresponding computational procedure was programmed.By taking Runyang Bridge over the Yangtze River as an example,the effects of the static wind action,wind speed spatial non-uniformity,and cable’s aerodynamic load on the flutter stability of the bridge were investigated numerically by virtue of the refined flutter analysis.The results show that the variations of structural dynamic characteristics and nonlinearity of wind load caused by the static wind action,spatial non-symmetric distribution of wind speed and aerodynamic load acting on main cables have significant influences on the flutter stability of long-span suspension bridges,and therefore should be considered accurately in the flutter analysis.