Embedded fiber Bragg grating transducer for concrete structures

Abstract

The photonic sensing technology is an area of very rapid growth and increasing interest nowadays. This is due in part to devices such as Fiber Bragg Gratings (FBG), whose inherent characteristics make them very suitable for different sensing fields such as civil engineering, aeronautics or medicine just to mention a few. Among the characteristics that make these devices so versatile, one can find their electromagnetic immunity due to the fact that they are made of dielectric material, both their low size and weight, and their ability to be multiplexed in the same fiber. Even more important is the fact that the information is wavelength encoded and so it is not altered by the attenuations of the transmission channel. This last characteristic transforms these devices into very reliable ones. A new FBG-based transducer for monitoring civil engineering structures is presented in this paper. It is able to monitor both strain and temperature at the same time, giving them very useful information about the actual behavior of their host structure. These transducers were fully characterized and tested in laboratory in order to evaluate their performance. The paper is organized as follows: first of all a brief theoretical introduced to FBG is given, and after that the design of the trasnducer is discussed. Then the characterization process, as well as its results, are presented. At the end, the final laboratory test in a well-known structure is described.