斜張橋的纜索在隨機車流及路面粗糙度下的動力特性

Abstract

基於斜張橋優美的外觀及相對便宜的造價，使得斜張橋被廣泛地應用於河流的跨越、鐵路橋梁以及山谷的聯通之上。但出乎意料地，在斜張橋廣泛地被應用的同時，斜張橋纜索在車行載重之下的動態行為模式卻鮮少成為學者的研究題材。而在無風或微風且少量車流之下，纜索的振動反應依然可被觀察到，此亦隱喻車輛行走於斜張橋亦可造成錨定於斜張橋上的纜索一定程度的振動反應。 考量纜索的安全性及可維持性，錨定於斜張橋上的纜索的振動問題是一個非常值得研究的問題。為了能夠多方面的完整考慮各種可能的車流，本文導入隨機車流的概念。此外，在路面不平整度方面，本文亦作了完整的研究，並發現當纜索頻率與任何橋梁或外在驅動頻率接近或重合時，纜索的振動反應亦可能被放大。本文各項分析所得的結果，應有助於解釋並進一步減少斜張橋纜索的振動。

Cable-stayed bridge has recently been wildly accepted as a structure for crossing rivers, railways, or valleys due to its aesthetic configuration and relatively low construction cost. However, it is surprising to note that despite its wide popularity, some of the dynamic behaviors of the cables on a cable-stayed bridge under the moving vehicular loads remain obscured. Furthermore, vibrations of cables have been observed under the normal traffic with virtually no winds or very mild winds, which imply that the moving traffic flows may play an important role at the vibrations of cables mounted on cable-stayed bridge. From the point of cable safety and maintenance, there exists a real need to study the vibration of cables mounted on a bridge under various traffic flows. In order to take as many as possible traffic flow cases into account, random traffic flow is introduced to the study. In the other hand, a thorough study is conducted for the pavement irregularities that may be present on cable-stayed bridges, through examination of the dynamic responses of the cables and bridge, from which it is concluded that the responses of cables in cable-stayed bridges will be amplified, when the frequency of the cable concerned coincides with any of the bridge or excitation frequencies. The results presented herein are useful for the design of bridge aimed at reducing the cable vibrations.