Standard optical fibers for load measuring of concrete structures using BOTDR

Abstract

Distributed fiber optic systems based on Brillouin Time Domain Reflectrometry BOTDR offer an exclusive solution for monitoring the load of large building structures such as buildings, bridges, tunnels, etc. Deformation measurements use special optical cables with added reinforcement element and a closer bond between cable jacket and fiber optic to achieve high sensitivity to mechanical deformation. Alternatively, cheaper standard optical fiber cables with single-fiber optic fibers are used. Alternatively, there is possible to use cheaper standard optical cables with single mode optical fibers. The paper deals with the analysis of the suitability of standard optical cables for the deformations measurement using a distributed BOTDR system. Several standard types of telecommunication optical cables were implemented into concrete beams and bent in a hydraulic press. The main result of this paper is the deformation sensitivities determination of optical cables for load measurement and the suitability analysis for embedding into the concrete beam with regard to long life.