Strain monitoring of smart bridge using fiber Bragg grating sensor system with wavelength-swept fiber laser

In this paper, we present an improved fiber Bragg grating (FBG) sensor system using a wavelength-swept fiber laser (WSFL). The WFSL provides unique and functional output characteristics useful for sensor interrogations. Proper monitoring of measurands in FBG sensor systems requires accurate measurement of the Bragg center wavelength, and the ability to track rapid shifts of the wavelength. For the purpose, we constructed a signal processing board with an electrical circuit and real-time signal-processing program using Labview software for storage and visualizing of the data. To improve its ability to acquire massive sensor signals, multi-channel sensor arrays were also constructed. The constructed FBG sensor system using WFSL and the real-time signal-processing program could successfully measure the strains of a composite laminated beam at nine sensing points. As a practical application of infrastructure, we demonstrate four FBG sensors in an optical fiber were used to monitor strains of the smart bridge model. When the smart bridge shows the response of near certain level of strain, the bridge tells early warning sound. This early warning system could give you time to undertake remedial works on bridges before the catastrophic disaster.