Investigation of Withinduced Vibration Control and Deterioration Counterrneasum for Stay-cables based on the Mechanisms of Aerodynamic Vthrations

本研究的目的是探讨基于卡曼涡强度的斜拉索气动不稳定性的机理，并研究控制方法和附加阻尼力以减小气动振动。本文将斜拉索尾流的轴向流动、斜拉索上表面形成的水沟、临界雷诺数效应等影响斜拉索气动不稳定性的各种因素作为卡曼涡减小的影响进行了讨论。例如，斜拉索尾迹的轴向流动较弱时，卡门涡的强度增大，而轴向流动较强时，卡门涡的强度变小。由此可以看出，如果轴向流动是非定常的，即卡门涡的强度也是非定常的，则可能发生非定常的舞动。同时，水流的位置控制着卡门涡的强度，在一定的水流位置处发生气动失稳。因此，风雨激振和干态驰振都是上述因素共同作用的结果，并用卡曼涡的减弱来解释这一机制。由于临界雷诺数的存在，质量阻尼性参数Sruton数对驰振不稳定性的影响对舞动很敏感，而对轴向流动产生的舞动较不敏感。此外，还需要更多的实际斜拉索干态驰振的现场观测数据。

The objectives of this study are to discuss mechanisms of aerodynamic instabilities of stay-cables based on intensities of Karman vortex and to investigate the control methods and additional damping for mitigating the aerodynamic vibration. The obtained information in this study must be useful to consider the countenneasuresibr stay-cable deterioration.In this study, all the factors for the aerodynamic instabilities of stay-cables, which are axial flow in the wake of inclined cable, water rivulet formed on the upper surface of the cable, critical Reynolds number effects and so on, are discussed as the effects of reduction of Karman vortex. For example, when the axial flow is weak in the wake of inclined cable, the intensity of Karman vortex increases and also, if the axial flow is intensive, the Karman vortex intensity becomes small. Then, it becomes clear that if the axial flow is unsteady, which means the Karman vortex intensity is also unsteady, unsteady galloping may occur. Also, the position of water rivulet controls the intensity of Karman vortex, and then, the aerodynamic instability occurs at the certain rivulet position. Therefore, the both rain-wind induced vibration and dry-state galloping must be generated by the combination of the above mentioned factors, and these mechanisms are explained by the reduction of Karman vortex.The effects of Scruton number, which is a mass-damping parameter, on the galloping instability are sensitive to the galloping due to the critical Reynolds number, but less sensitive to the galloping generated by the axial flow. Furthermore, more field observation data of the dry-state galloping of the real stay-cables must be needed.