Recently, fibre-optic Bragg grating (FBG) sensors have been well recognised as intrinsic structural health monitoring devices for advanced composite related structures. The embedded FBG sensors, due to its extremely small physical size can provide the information to a high accuracy and resolution without influencing the dimension and mechanical properties of the structures. This paper presents a brief review of the principles of the FBG strain sensing technologies for infrastructure applications. The use of multiplexed FBG sensors is able to measure true strains of composite and composite strengthened concrete structures. The sensors were embedded at the interface between the concrete surface and externally bonded composite patches. The experimental results showed that the FBG sensors often gave high strain values compared with surface mounted strain gauges, particularly for the use of thick composite materials. The sensors attached on the surface of the concrete were highly susceptible to micro-cracks of the concrete and delaminations at the bond interface. These phenomena could not be real-timely and accurately detected through the use of other non-destructive evaluation techniques in site. The experimental results from the measurements of static and dynamic strains in advanced composite and composite repaired concrete structures are also discussed in this paper.
展开▼
