Assessment of Long-term Performance of EFPI Fibre Optic Sensors

摘要

Large and complex structures are being built to meet the growing demands and these are exposed to severe and harsh environmental conditions. The type of strain sensor and method of installation should provide reliable measurement of strain over a long period. Among the different strain sensors available, fiber optic sensors are found to be reliable for long-term monitoring of structures. Flexibility, small size and corrosion resistance of optical fibers allow them to be directly embedded into concrete structures. The inherent advantages of fiber optic sensors include high resolution, ability to be embedded in common construction environment, immunity from electro magnetic interference, large band width of signal, practically no noise and high sensitivity. Structures instrumented with fiber optic sensors are in a way capable of serving a dual purpose by providing in-place quality control of concrete at early ages and facilitate prediction of structural anomalies there after. The concept of long-term monitoring of civil engineering structures is evolving as a result of the requirement of cost-effective maintenance of complex structures and the development of new sensor technologies. Experimental studies were carried out to evaluate the performance of interfero-metric based fiber optic sensors for strain measurements and assess their suitability for long-term monitoring of civil engineering structures. This paper brings out the potential of fiber optic sensor system for long-term monitoring of concrete structures. The stability and reliability of Extrinsic Fabry-Perot Inter-ferometric (EFPI) fiber optic sensor for long-term strain monitoring of civil engineering structures is demonstrated from the laboratory studies. Brief details of the laboratory studies carried out on fiber optic sensors are also covered in this paper. From the laboratory demonstration of the behaviour of fiber optic sensor under long-term loading, the EFPI fiber optic strain sensors are found to be useful in health monitoring of major civil engineering structures.