Study on Suspension Type Bridges Multi-Strand Cable with Economical and Aerodynamic Performances

本文从经济性和气动性能两方面对长悬索桥用多股缆索的研制进行了研究。斜拉桥的斜拉索和悬索桥的吊索在风的作用下会产生不同类型的振动。为了抑制气动振动，人们进行了许多研究。本文从气动稳定性和制造、运输、安装等方面考虑，提出了螺旋钢丝多股电缆。多股电缆由小股电缆组成，因此增加了工厂制造小股电缆，无论所需电缆容量如何，运输和安装设备都需要小容量。多股电缆的外部形状是不均匀的，这种形状对抑制涡激振动和风雨激振等气动振动有很好的效果。实验在九州工业大学1780 × 790 mm试验段的风洞中进行。实验中使用的模型是由铝管制成的刚性模型。模型在升沉运动中由四个螺旋弹簧弹性支撑。进行了响应观察和表面压力测量。通过对钢索表面压力的测量，证明了螺旋钢丝多股钢索能够抑制各种气动振动。多股线与螺旋线凹槽之间的间隙使表面压力适当平滑，从而起到抑制气动振动的作用。

The present study aims at the development of multi-strand cable for a long suspension type bridge from viewpoint of both economical and aerodynamic performances. Stay cables of cable-stayed bridges and hanger cables of suspension bridges are known to have various types of vibration under wind action. In order to suppress the aerodynamic vibrations, many researches have been conducted. In the present study, multi-strand cable with helical wire is proposed from viewpoint of aerodynamic stability and of cost performance of manufacture, transportation and erection. The multi-strand cable is composed of small strands, therefore adding to the manufacturing small strands in the factory, small capacity is needed for transportation and erection devices regardless of required cable capacity. The outer shape of the multi-strand cable is uneven and the shape gives good performance to suppress the aerodynamic vibrations such as vortex-excited vibration and rain-wind-induced vibration. The experiments were conducted in the wind tunnel with test section 1780 x 790 mm of Kyshu Institute of Technology. The models used in the experiments were rigid models made by the aluminum pipe. And the model was elastically supported in heaving motion by four coil-springs. The observation of response and measuring surface pressure were conducted. It was clarified by measuring surface pressure of the cable that the multi-strand cable with helical wire can suppress the various aerodynamic vibrations. The mechanism of suppressing aerodynamic vibrations is seemed that the gap between grooves on multi-strand and helical wire makes the surface pressure appropriately smooth for suppressing vibrations.