摘要
大跨度悬索桥吊索常发生大幅风致振动,一种可能的机理为吊索索股间的尾流致振。为研究吊索表面粗糙度对其气动稳定性的影响,分别针对平行钢丝吊索和钢绞线吊索,制作表面光滑、粗糙索股模型,进行测力风洞试验,得到光滑和粗糙下游索股的平均气动力系数,在此基础上,依据Routh-Hurwitz稳定性判据,对平行钢丝吊索和钢绞线吊索的气动失稳区域进行比较研究。结果表明:平行钢丝吊索与钢绞线吊索的平均气动力系数空间分布特征存在较明显区别;两种吊索的不稳定区域整体上呈条带状,宽度约为1~2D,且平行钢丝吊索的失稳区域向中心线两边发散的比钢绞线吊索更为明显;在3≤X≤4区域,尾流吊索发生气动失稳可能性较大,特别是钢绞线吊索。
The hangers on the long-span suspension bridges often vibrate under the action of wind. The wake-induced vibration caused by the aerodynamic interference between the hangers might be one of the underlying mechanisms. In order to study the influence of the surface roughness of the hanger on the aerodynamic stability, two types of model hangers with smooth and rough surfaces, which correspond to the parallel wire and steel strand hangers respectively, were made carry out wind tunnel tests to measure the mean aerodynamic force coefficients of the leeward cables. Then, according to the Routh-Hurwitz stability criterion, the aerodynamic instability regions of the parallel wire and steel strand hangers were studied and compared. The results show that there are some differences between the spatial distribution of the mean aerodynamic force coefficients for the smooth leeward cylinder and that for the rough leeward cylinder. The unstable region of the two kinds of leeward hangers appears to be a strip shape with a width of 1~2D, while the unstable region of the parallel wire hanger diverges on both sides of the center line more obviously than the steel strand hanger. The possibility of aerodynamic instability is greater in the region of 3≤X≤4, especially for steel strand hanger.
引文
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