Evaluation of Fiber Optic Strain Measurement System for Monitoring FRP Bridge Decks

Abstract

The use of Fiber Optic sensors for structural monitoring applications has attained popularity among researchers and practitioners recently due to their immense advantages. This paper discusses a continuous structural monitoring technique using surface mounted and embedded fiber optic strain sensors to measure the strain in FRP bridge decks. An Extrinsic Fabry‐Perot Interferometric (EFPI) strain sensor was selected for evaluation as it offers a good compromise between accuracy and cost considerations. This EFPI strain sensor, along with a conventional strain gauge, was surface mounted on a FRP bridge decks. The decks were then subjected to an accelerated aging test in an environmental chamber and the performance of both the strain sensors was recorded for a performance comparison. The results from the seven months of accelerated aging that is equivalent to 10 years of actual life show that the strain gauge sensor and the EFPI Fiber Optic sensor are still in working condition. The EFPI fiber optic sensor detects minute and sudden changes in strain more effectively than the strain gauge sensor. Placement in the environmental chamber did not affect the EFPI sensor’s performance and is an indication of its applicability to field structural monitoring for lengthy periods of time. The second part is a preliminary work where a fiber optic sensor was embedded inside a FRP plate during the pultrusion process. This shows the feasibility of manufacturing FRP bridge decks with embedded fiber optic sensors.