Design a bridge scour monitoring system by pressing the fiber Bragg grating with a rolling pulley mechanism

In this paper, we design an optical fiber sensor based on fiber Bragg grating (FBG) for real-time bridge scour monitoring. The sensing element of the FBG is embedded in the silicone rubber, and the two ends of the rubber are fixed on the metal plate. The pulley has a circumference of 0.2 m and will drive the threaded screw, has a pitch of 1 mm, forward to press the rubber. When the rubber is pressed by the threaded screw, we can measure the reflection central wavelength shift from FBG sensor to obtain the scour depth. Bridge scour is one of the main causes of bridge failures that is resulted by the interaction of flood water and soil-structure at the bottom of the river. Monitoring scour is very important to ensure the continued safe operation of the bridge traffic and the passing through person’s life and property. A prototype of temperature-insensitive scour sensing system was designed and fabricated to test its sensing characteristics in the laboratory. The design criterion of scour sensor is to achieve the highest sensing pier scour depth of ≥ 4 m. The robust experimental results prove that the proposed system will ensure the effectiveness and feasibility in the field.