使用嵌入纖維增強基質之光纖傳感器進行結構損傷監測

現今改建加固不能完全地降低受損結構物倒塌的風險，因為強烈地震可能在短時間內再次發生。因此光導纖維傳感器系統被運用於結構物裂縫的連續監測。光纖傳感器的體積小而且在應變、應力、溫度測量的高敏感度及準確性，使他們被廣泛地運用於各式各樣的工程結構中，像是橋墩、大壩、隧道的剪切破壞以及結構牆的剪切破裂監測。光學傳感技術成功地連結了變形量與OTDR軌跡中光脈衝的能量損失。本研究中將描述該技術結合光導纖維聚合物及光子計數光時域反射儀的理論與發展，同時也簡要地介紹OTDR的性質及重要參數，像是動態範圍、空間分佈率及盲區。分佈式光纖傳感器提高安全性也降低了維護的成本。藉由傳感器的監測，結構物早期的損害能夠及時地被發現並且修補。本研究中多個事件於OTDR的軌跡中，主要考慮剪切破壞模式。透過OTDR的訊號進行光纖傳感，並利用強度差值法研究最大剪切強度的單剪切事件。此外也研究間隔分別為25公分、50公分、5公尺及10公尺的雙剪切事件。

關鍵字

光纖傳感器；光時域反射儀；光子計數

並列摘要

Nowadays, because of the possible recurrence of strong seismic tremors within a short period of time, retrofit is not enough to guarantee that the collapse risk of the damaged structures can be completely mitigated. Therefore, fiber optic sensor systems have been deployed to continuously monitor the structural cracking. Mainly due to their small size, show high sensitivity and accuracy in strain, stress, temperature measurement, they are able to be widely used in various engineering structures such as shear failure of bridge piers, dams, tunnel and shear cracking of structural wall. In this study, presents the development of an optical sensing technique and theory using Optical Fibers Sensor (OFS) and Photon-counting Optical Time Domain Reflectometer (v-OTDR). The proposed technique is successfully related the deflection magnitudes to the energy loss of the light pulses in OTDR traces. Also briefly introduced the nature and most important parameters of ODTR, such as the dynamic range, the spatial resolution and the dead zone. The benefit of these distributed fiber optical fiber sensor to increase of safety is also a commercial one since damages can be detected and repair at an early stage thus decreasing the maintenance costs. The shear failure mode is mainly considered to detect multiple events in OTDR traces. Use optical fiber sensing with OTDR signals under single shear events with the maximum reflection intensity using the intensity difference methods and double shear events with separations of 25cm, 50cm, 5m, and 10m respectively are investigated.

並列關鍵字

optical fiber sensor ； optical time domain reflectometer ； Photon-counting (v-OTDR)

參考文獻

References

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