以鋼纜微振訊號進行鋼纜與橋體之振態頻率識別

Modal Frequency Identification for Cable and Girder Using Ambient Cable Vibration Signals

陳建州(Chien-Chou Chen) ； 吳文華(Wen-Hwa Wu) ； 廖釗銨(Jau-An Liau)

《中國土木水利工程學刊》 20卷4期 (2008/12) Pp. 509-521

https://doi.org/10.6652/JoCICHE.200812_20(4).0005

摘要

為確保斜張橋長期的使用性與安全性，橋體損傷的監測與診斷乃成為一個相當重要的研究課題。以往較多的研究著重於直接經由量測橋體振動特性的改變，以研判橋梁構件可能損傷的位置與程度。由於橋體微振的量測與識別作業常有實際執行上的困難，位於橋體內力傳遞必經途徑的斜張鋼纜即成為一個值得探討的量測對象。本研究首在於說明斜張鋼纜的振動特性，再藉由集鹿斜張橋之實際鋼纜微振量測資料探討如何分析判讀鋼纜自然振動頻率，以及橋體的自然振動頻率，研究成果將可應用於簡化橋體損傷的診斷。

關鍵字

斜張鋼纜 ； 橋體 ； 振態頻率 ； 微振量測

並列摘要

In order to guarantee the long-term serviceability and safety of cablestayed bridges, the development of feasible methods in monitoring and diagnosing the bridge damages has become an important issue in related researches. Most of the previous methods directly adopted the measurements from girder to detect its changes in dynamic characteristics and then identify the possible extent and location of bridge damages. However, it generally requires a great amount of efforts in measuring and analyzing the ambient vibration signal from girder. Since the stay cables are the primary members in transmitting the internal forces of the whole structure, it is consequently obvious to consider them as a more convenient measuring target for the damage recognition of cable-stayed bridges. The major objective of this study is to develop a systematic method for identifying the natural frequencies of stay cables as well as those of girders from the ambient cable vibration signals. The dynamic characteristics of stay cables are first described in this paper, followed by the demonstration of this method using the ambient cable vibration measurements from the Chi-Lu Cable-stayed Bridge. It is expected that the results of this research will simplify the diagnosis of structural damages of cable-stayed bridges.

並列關鍵字

stay cable ； girder ； modal frequency ； ambient vibration measurement