Bridge Monitoring Using Brillouin Fiber-Optic Sensors

We report the results of a static load test performed on a road-bridge with a span length of 44.40 m. The tests were performed by a portable prototype instrument exploiting stimulated Brillouin scattering in optical fibers for deformation and temperature measurements. The optical fiber sensor was able to provide the strain distribution along a supporting beam of the bridge with a spatial resolution of 3 meters and a strain resolution of ±15 με. Comparison of fiber-optic measurements with finite-elements-method (FEM) simulations, as well as with data collected by vibrating wire strain gauges, confirmed the validity of the SBS-based approach in monitoring the deformation of large structures.

I. Introduction

The Safety assessment of ordinary structures is usually based on the experimental testing of displacements or strains under the design loads, by taking into consideration measures related to a selected discrete number of points. Such a knowledge database can produce savings through an optimization of the maintenance intervention and through the possibility of extending the life of the infrastructure, while at the same time keeping an optimal safety level. For many engineering works of strategic significance like bridges, pipes, rising buildings, dams and tunnels, safety should be continuously assessed during their entire lifetime.