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

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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.