車橋互制理論於橋梁損傷識別之應用

在地震與颱風等天災過後，橋梁的安全性是相當重要的課題。橋梁頻率為一項十分重要的振態參數，它隨著橋梁結構勁度的改變而改變；相對模態振型和阻尼而言，橋梁的頻率資訊比較容易擷取，因此有關橋頻的量測法，在過去的半個世紀已有成熟的發展。傳統的橋梁識別方法是直接將感測器安裝於橋梁上，並利用感測器所量測到的橋梁動力反應，進行頻率之識別，此法稱之為直接量測法。自2004年以來，Yang等首創另外一種量測方式，以改善直接量測法的缺點，提供更機動且經濟的好處，吾人稱之為間接量測法，其概念是將感測器安裝在移動的車輛上，讓車輛行駛通過橋梁並記錄其反應，再從車體的動力反應分析中擷取出橋梁的頻率資訊。由於其具高機動性，在天災之後能更快速地檢測橋梁並獲取相關模態資訊，提供工程師破壞檢測與安全評估之參考依據。本研究目的在於利用數值模擬，進行橋梁間接量測法之探討。首先，從基本的車橋互制理論開始推導，探討光滑路面下的間接量測結果。接著，引入路面粗糙度之影響，分析在不同等級路面粗糙度下量測車車體之反應。此外，也將利用前後相連的伴隨車通過橋梁，所獲致的反應頻譜，予以相減，以排除路面粗糙度干擾之影響。另外，針對數個假設的損傷情境，將嘗試利用結構傳遞率，來進行橋梁結構的損傷識別。最後，根據本文各章的例題分析，吾人將針對各種案例及其效應提出具體結論，並對未來研究之研究方向提出參考意見。

關鍵字

橋梁；損傷識別；頻率；間接量測法；路面粗糙度；量測車；車橋互制；結構傳遞率

並列摘要

It is an urgent matter to confirm the safety of brides after the occurrence of major disasters such as earthquakes and typhoons. The frequency of vibration is one of the important properties for bridges, as it can reflect the change in stiffness of the bridge. Compared with the modal shape and damping ratio, the frequency of a bridge can be measured in a relatively easy way. In the past half a century, techniques developed for the measurement of bridge frequencies are considered mature. Conventionally, to measure the bridge frequencies, we have to mount directly the sensors on the bridge and use the vibration response recorded by the sensors to identify the frequencies. Such an approach has been referred to as the direct approach. Starting from 2004, a new method for measurement of bridge frequencies, referred to as the indirect approach, has been proposed by Yang and co-workers aimed at overcoming the drawbacks of the direct approach, while offering advantages such as mobility and economy. With this approach, a test vehicle mounted with vibration sensors is allowed to pass the bridge of concern, and the response recorded of the vehicle during its passage is then used to extract the bridge frequencies. Due to its mobility, this approach is particularly suitable for measuring the bridge frequencies after the occurrence of a major natural disaster, which can offer an in-time reference for engineers to evaluate the safety of bridges. The objective of this thesis is to use the numerical approach to simulate the indirect measurement of bridge frequencies. First of all, we shall adopt the theory of vehicle-bridge interaction to study the indirect measurement of bridge frequencies for the case of smooth road surface. Next, we shall introduce the effect of road surface roughness and investigate the response of the test vehicle under various levels of roughness profiles. In addition, we shall consider the case of two test vehicles in connection, allow them to pass the bridge of concern, and then deduct the spectral response obtained for one vehicle from the other so as to eliminate the pollution effect of road surface roughness. Moreover, for various scenarios of damages, the transmissibility of a structure will be computed for identifying the damages in the bridge. Finally, concluding remarks will be drawn for the numerical examples presented in this thesis, while directions for possible future research will be highlighted.

並列關鍵字

bridge ； damage identification ； frequency ； indirect measurement approach ； road surface roughness ； test vehicle ； vehicle-bridge interaction ； transmissibility

參考文獻

[47] 李育謙(2011),「濾波技巧於橋梁頻率間接量測法之應用」，國立台灣大學土木工程學系碩士論文

[48] 吳侑軒(2014),「車橋互制理論於橋梁頻率間接量測法之應用」，國立台灣大學土木工程學系碩士論文

[1] Brincker, R., Zhang, L., and Andersen, P. (2001), "Modal identification of output-only systems using frequency domain decomposition", Smart Materials and Structures, 10(3): 441-445.

[3] Brownjohn, J.M.W., Xia, P.Q., Hao, H., and Xia, Y. (2001), “Civil structure condition assessment by FE model updating: methodology and case studies”, Finite Elements in Analysis and Design, 37, 761-775.

[4] Bu, J. Q., Law, S.S., and Zhu, X. Q., (2006),”Innovative bridge condition assessment from dynamic response of a passing vehicle”, Journal of Engineering Mechanics Division, ASCE, 132(12): 1372–1379.

國際替代計量

車橋互制理論於橋梁損傷識別之應用

全文下載

主題瀏覽