Application of optical fiber sensor in civil structural monitoring

From many points of view, fiber optic sensors are the ideal transducers for civil structural monitoring. Being durable, stable and insensitive to external perturbations, they are particularly interesting for the long-term health assessment of civil structures. On the other hand, the small size and the relative fragility of the naked fibers are apparently incompatible with the hostile environment usually found in civil engineering. In this contribution we will however show that with adequate packaging and careful design of the sensors and their accessories, fiber optic sensors can match and surpass conventional sensors, not only in their measurement performance, but also in the ease of use and survivability. This paper resumes the nine year long experience of our group in the installation of fiber optic sensors in the most diverse structure types, including bridges, tunnels, dams, piles, anchors, historical monuments, nuclear power plants and many others. To date, we have installed about 1'500 sensors in almost 70 different applications. Statistics show that, by proper handling, it is possible to achieve 95-100% survivability during installation and for many years afterward.