Distributed optic fiber sensing textile installation inside a novel composite girder bridge

Abstract

This paper designed and fabricated a distributed fiber optic sensing textile for a composite bridge's structural health monitoring (SHM). Based on the Brillouin optical time-domain analyzer (BOTDA), the sensing textile can achieve the resolution of 1m distributed sensing ability. Unlike electrical sensors, fiber sensing systems enjoy the advantages of resistance to electromagnetic interference, survivability withstanding harsh environments, and can interrogation over kilometers. The embroidery machine from Saint-Gobain embedded the fiber system into the textile material. We have designed a U-shape fiber sensing structure including two arms of 22m each. Each arm can be used as a distributed sensing section. Embedded fiber optic sensing textile would result in reduced installation time, which lowers the labor cost and the work stoppage cost, which can be substantial for certain applications like long-range monitoring. Also, textile provides additional protection and allows the design of different layout patterns to accommodate the requirements of a project. The fiber sensing system was installed inside the girder before the bridge was built. We investigated a novel installation method using slides moving inside the girder and epoxy was applied to fix the sensing textile on the bottom side of the girders. The sensing system was tested after the bridge was built and demonstrated the feasibility of distributed fiber sensing system for monitoring composite bridges. The results indicated the potential of distributed fiber sensing systems in structural health monitoring and provide a solution of small size, low cost, high durability fiber sensing system.