Dynamic Brillouin Scattering–Based Condition Assessment of Cables in Cable-Stayed Bridges

Abstract

A method for structural health monitoring of cable-stayed bridges based on the dynamic distributed sensing of bridge deck strains is introduced in this article. The objective is to detect the location and the magnitude of the cables that have totally or partially lost their tensile load-carrying capacities. Dynamic sensing provides a realistic approach for condition assessment of the bridge under operational conditions. A Brillouin scattering optical time domain analysis (BOTDA) fiber-optic sensor was used to monitor the distributed strain in the deck of a scaled model cable-stayed bridge in the laboratory. The formulations developed in the present study take advantage of the dynamic distributed sensing capability of the BOTDA in amplitude transfer (AT) mode for the establishment of a relationship between the redistribution of deck strains and the tension loss in the individual cables of cable-stayed bridges. The experimental program involved single cable and multicable damage scenarios. The applicability of the method was independently evaluated by the direct measurement of cable forces and nonlinear finite-element analysis of the bridge.