| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 100 === Before an assessment can be conducted on the damage level of the bridge, it is essential to obtain the dynamic parameters of the bridge, including particularly the natural frequencies of vibration. Traditionally, bridge frequencies are measured from the dynamic response of the bridge via the vibration sensors directly mounted on the bridge, referred to as the direct approach. In recent years, there has been a fast development on the bridge frequency techniques. One of these methods, called the indirect approach, has been proposed. The idea of this method is to obtain the bridge frequencies indirectly from the dynamic response recorded on a moving vehicle during its travel of the bridge of concern. Compared with the direct approach, the indirect approach has the advantage of portability, rapidness and economical efficiency. It is also the primary choice when encountering major natural disasters such as earthquakes, which requires safety examination over a vast amount of bridges in a short time.
Through a series of field tests, the objective of this study is to improve the performance of the testing vehicles and related devices. The results indicate that the methods proposed by this research are both useful and effective. Moreover, this research also considers the feasibility of using the indirect approach to measure different types of bridges, focusing on the three main factors that affect the retrieval of bridge frequencies, i.e.,weight of the test vehicle, advancement speed and rate of random vehicle flow on the bridge. These data are then analytically compared. Concluding remarks are drawn at the end of this study to provide insight for future field tests and reference for further researches.
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