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

特高压输电线路、缆索支承桥梁等大跨度线形结构具有很强的柔韧性，在设计时必须对其抗风稳定性进行校核。由于跨度很大，有一些特殊的问题需要仔细研究。其中一个问题是风作用沿结构跨度的不均匀对结构风致振动的影响。本文考虑了局部均匀风的作用，通过试验和分析研究了局部风作用下结构的振动特性。主要研究成果如下：1.采用大跨度张拉带模型进行了风洞试验，部分张拉带模型受风作用。研究中考虑了两个不同截面的模型：一个是矩形圆柱体，另一个是圆柱体。以部分均匀风的位置和均匀风作用的长度为基本测试参数，对张拉板模型的风振进行了测量。详细讨论了风的局部化作用对结构振型等结构响应的影响。2.分析了波浪在大跨度结构中的传播，并研究了张弦情况下波浪的传播特性。研究了下垂拉索振动的主动波控问题，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.