Development of a long-term monitoring system based on FBG sensors applied to concrete bridges

Structural health monitoring has become increasingly valuable in recent years and is starting to take a leading role in the field of structural engineering. Monitoring systems based on fiber optic technology have proved to exhibit meaningful benefits when compared with the current solutions of an electric nature. However, further development of this technology is needed to achieve its efficient and widespread use in the structural health monitoring of bridges. The development of new and efficient transducers is mandatory to expand this novel technology to the field of civil engineering. This work is focused on the development and application to concrete bridges of new and reliable optical based transducers, more specifically, a vertical displacement transducer and a strain transducer to be embedded into concrete, both based on Fiber Bragg Grating (FBG) sensing technology. The conception and the development of these innovative transducers, aiming at their integration in the structural health monitoring of concrete bridges, are referred to. A field application of the developed transducers is presented invoking the advanced optical based structural monitoring system of the Lezíria Bridge. The system’s conception, the adopted sensors network architecture, and the practical installation of a monitoring system based on FBG sensors are discussed. Finally, the operation mode and the performance of the optical based structural monitoring system used for the permanent surveillance of the Lezíria Bridge are described and appraised.