Structural NDE of concrete structures using protected EFPI and FBG sensors

This paper is concerned with the design concepts, modelling and implementation of various fibre optic sensor protection systems for development in concrete structures. The design concepts of fibre optic sensor protection system and on-site requirements for surface-mounted and embedded optical fibre sensor in concrete structures have been addressed. The aspects of finite element (FE) modelling of selected sensor protection systems in terms of strain transfer efficiency from the structure to the sensing region have also been focused in this paper. Finally, the experimental validations of specified sensor protection system in concrete structures have been performed successfully. Protected extrinsic Fabry–Perot interferometric (EFPI) and fibre Bragg grating (FBG) sensors have been used to monitor the structural health status of plain and composite wrapped concrete cylinders. Results obtained indicate that the protection system for the sensors performs adequately in concrete environment and there is very good correlation between results obtained by the protected fibre optic sensors and conventional electrical resistance strain gauges.