Fundamental Study on Wind-induced Vibrations of Long-Spanned Linelike Structures

大跨度的线状结构，如特高压输电线路和电缆支撑的桥梁是如此的灵活，在设计时必须检查抗风作用的动态稳定性。由于跨度太大，有一些特殊的问题需要仔细研究。其中一个问题是沿结构跨度的风作用的不均匀性对其风致振动的影响。本研究考虑局部均匀风，对局部风作用下结构振动特性进行了实验和分析研究。实验采用埼玉大学试验段为50*50 cm的风洞。主要研究成果总结如下：1。采用大跨度拉紧条形模型进行风洞试验，并对部分模型进行了风洞试验。研究中考虑了两种不同截面的模型：一种是矩形圆柱体，另一种是圆形圆柱体。以部分均布风的位置和均布风作用的长度作为基本测试参数，测量了拉紧条模型的风致振动。详细讨论了局部风作用下结构响应的变化，如振型的变化。分析了波在大跨度结构中的传播特性，并研究了在拉紧弦的情况下波在大跨度结构中的传播特性。研究了斜拉索振动的主动波控制问题，并对其控制性能进行了研究。

Long-spanned linelike structures such as UHV transmission lines and cable-supported bridges are so flexible that the dynamic stability against wind actions must be checked in their design. Because of the very long span, there are some peculiar problems which should be studied carefully. One of the problems is the effect of non-uniformity of the wind action along the span of structure on its wind-induced vibrations. In the present study, partially uniform wind was considered and the characteristics of structural vibrations induced by the localized wind action were investigated experimentally and analytically. The wind tunnel with the testing section of 50*50 cm in Saitama University were used for the experiments.The main research results are summarized as follows.1.The wind tunnel experiments were conducted with long-spanned taut strip model, a part of which was subjected to the wind flow. The models with two different cross-sections were considered in the study : One is a rectangular cylinder and another is a circular cylinder. The wind-induced vibrations of the taut strip models were measured by taking the location of the partially uniform wind as well as the length of uniform wind action as fundamental testing parameters. The changes in the structural responses, such as vibration modes, caused by localized action of wind were discussed in detail.2.The propagation of waves in the long-spanned structures was analyzed and its characteristics was investigated in the case of taut strings. The active wave control of sagged cable vibrations was also dealt with in the study and its control performance was also investigated.