A Combined Positioning Method Used for Identification of Concrete Cracks.

Fully distributed fiber optic sensors are characteristically used for the measurement of long distances and continuous distribution of space. However, due to the different fiber type, fiber length, ambient temperature and strain, fully distributed fiber optic sensors fail to locate damage accurately and cause a greater error. Therefore, this paper proposes a new positioning method of combining fully distributed fiber optic sensors with fiber Bragg gratings, which enables accurately the localization of a structural damage during the long-term monitoring of fully distributed fiber optic sensors. Moreover, the coupling mechanism of the reflected light from fiber grating and excited Brillouin scattering light is illustrated. Further, it is experimentally verified by locating the cracks of 2 m long reinforced concrete beams. The experimental results show that this proposed method is capable of monitoring the generation of the beam crack and further locating the crack on the concrete beam with an approximate error of 10 cm.