大跨度中央开槽钢箱梁悬索桥颤振关键参数研究

Research on key parameters of critical flutter wind speed for slotted steel box girder suspension bridges

中央开槽钢箱梁作为第三代钢箱梁,可改善结构的气动性能,提高颤振临界风速,但开槽箱梁的优化选型受多种因素影响。为全面阐述开槽箱梁的气动优化选型规律,通过风洞试验和数值方法综合研究了多个关键参数对颤振性能的影响:通过节段模型风洞试验,研究了开槽比对颤振临界风速的影响规律,并获得了多组颤振导数;采用二维颤振直接分析数值算法,研究了钢箱梁的几何参数、质量参数、频率参数和纵向遮盖率等对悬索桥颤振临界风速的影响规律。研究发现:颤振临界风速随开槽宽度增加先增大后减小,存在最优开槽比;开槽宽度增加使质量和质量惯矩增大,质量和质量惯矩的增加有利于颤振稳定性能的提高;随着扭转频率的增大颤振性能增强,竖弯频率则相反;纵向遮盖各工况也存在最优遮盖率,影响颤振的规律与中央开槽类似;颤振临界风速对各个参数的敏感度不同,敏感度从小到大依次为:质量、竖弯基频、质量惯矩、扭转频率。该研究成果可为开槽箱梁的气动选型提供参考。

The central slotted steel box girder, as the third generation steel box girder, can improve the aerodynamic performance of the structure, especially increasing the critical flutter wind speed. However, the selection of the optimal type of the slotted box girder is affected by multiple factors. In order to comprehensively expound the optimal configuration of the central slotted box girder, this paper carries out research on the influence of multiple key parameters on the flutter stability, utilizing wind tunnel tests and numerical simulation. Firstly, the effect of the slot ratio on the critical flutter wind speed is studied by section model wind tunnel tests, and multiple flutter derivatives are identified. Thereafter, the effects of the geometric parameter, the mass parameter, the frequency parameter, and the longitudinal coverage ratio on the critical flut- ter wind speed are investigated through two dimensional flutter straight forward method. Research shows that the critical flutter wind speed first increases and then decreases as the slot width increases, and there is an optimal slot ratio the increase of the slot width enhances the mass and the moment of inertia, the increase of the mass or the moment of inertia is beneficial to the flutter stabiiity; the increase of torsional frequency is favorable to the flutter stability while the vertical bending frequency plays a contrary role; the effect of the longitudinal coverage ratio on the flutter stability is similar to that of the central slot, and there is also an optimal longitudi- nal coverage ratio; the parameter susceptibility is sequenced from low to high as mass, bending frequency, moment of inertia and torsional frequency. Research results can provide a reference for the aerodynamic type selection.