| Summary: | In Canada, the extent of deterioration has prompted many authorities, including the federal and provincial governments, to investigate the potential use of fibre-reinforced polymer (FRP) products to extend the life of their existing structures. Fibre optic sensors (FOS) are serious candidates for the long-term monitoring of both existing and new structures throughout their working life. Research up to date demonstrated the potential of both FRP and FOS systems in the civil engineering field. The FRP systems used as an external reinforcement proved to be very efficient in increasing the strength of concrete structures. However, few studies focused on the long-term durability of these materials when used as external reinforcement of RC beams. As a result, there is a concern regarding the fatigue resistance of these materials when they are exposed to harsh environmental conditions. Previous studies showed that the FOS systems were successfully integrated in FRP products and tested in various loading conditions. A few studies touch upon the fatigue resistance of FOS, and no study has been reported on their durability when exposed to aggressive environments. It is important to understand the behaviour of FOS when they are submitted to these conditions before implementing them extensively in long-term health monitoring projects. This extensive experimental project was undertaken in order to assess the durability of FOS systems installed on the FRP used as external reinforcement for reinforced concrete beams. Knowing that the FOS installed on a support structure was submitted to various loading and water exposure conditions, the durability of both the FOS and RC beams strengthened with carbon-fibre-reinforced polymers was assessed. The originality of this study consists in the fact that, to the author's knowledge, it is the only experimental program on the durability of FOS installed on a structural element submitted to various fatigue and post-fatigue loading conditions. In addition, it combines the effects of fatigue loading with water exposure conditions. The maximum strain values as well as the numbers of fatigue cycles to which the FOS were tested are larger than in any other previous study. Moreover, the RC beams strengthened with FRP tested in the same conditions with the FOS, were submitted to environmental fatigue, that is water exposures combined with fatigue loading. Finally, the impact resonance method (IRM), a non-destructive testing technique, was for the first time employed to monitor fatigue damage for this type of specimens."--Résumé abrégé par UMI.
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