Various types of optical FBG sensors and their applications in SHM

As one of the most important inventions in measurement field in the late 20th century, optical fiber Bragg grating (FBG) based sensors have been greatly recognized and largely applied in long-term structural health monitoring (SHM). In this paper, various types of optical FBG sensors and applications in SHM are introduced. The main contents include direct FBG-based sensors, indirect FBG-based sensors, FBG based smart structures, and the applications of FBG sensors in some typical civil infrastructures. Finally, some directions of researches and applications have been recommended. Researches and practical applications show that FBG sensors have become one of the key sensors in long-term SHM instead of some conventional electrical sensors.