Evaluation of fibre optic sensors for structural condition monitoring

This paper presents fibre optic sensing technology for strain monitoring of engineering materials and structures. The research program consisted of laboratory tests including thermal tests, tensile tests and flexural tests, and a field application on a concrete bridge deck (Joffre Bridge) reinforced partly with fiber reinforced polymers (FRP). Four types of Fabry-Perot fibre optic sensors were investigated and compared to other types of strain gauges including Bragg fibre optic sensors and resistance strain gauges. Typical field monitoring results from the static and dynamic tests using calibrated-truck loads on the Joffre Bridge are also presented in this paper. Experimental and field monitoring results show that Fabry-Perot fibre optic sensors perform linearly and show good response to thermal variations and mechanical loading conditions. The fibre optic sensing technology shows an enhanced accuracy and has potential for significant improvement in the long-term monitoring of strain levels in field applications over conventional strain gauges. It is a promising technique for long-term ‘health’ monitoring of new and rehabilitated structures.