Building up the Level Sensing System for Bridges by Gravity, Water, Laser and Optical Fiber

Building up the Level Sensing System for Bridges by Gravity, Water, Laser and Optical Fiber

This paper focuses on the design and application of optical-fiber differential settlement measurement (DSM) sensors for bridges. By using the law of connected vessels, the buoyancy principle, an equilibrium force condition, and the photoelasticity of Fiber Bragg Grating (FBG), the DSM sensor is easily manufactured and is sensitive to the level change. Aside from the design principle, this study illustrates the application of the DSM sensors on underpass bridges. From the field results, it is shown that the proposed DSM sensors are stable and precise enough to monitor the behavior of multiple-span underpass bridges. The aim of this study is to share the optical fiber DSM field results.