Crack detection in hydraulic concrete structures using bending loss data of optical fiber

Huaizhi Su 1,2, Xing Li 2, Bin Fang 3 and ZhipingWen 4

1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, China

2 College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China

3 National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing, China

4 Department of Computer Engineering, Nanjing Institute of Technology, Nanjing, China

Journal of Intelligent Material Systems and Structures 1–15

Abstract

Due to low tensile strength of concrete, seasonal temperature, shrinkage of concrete, and so on, many of hydraulic concrete structures experience cracking. An optical fiber–based approach is introduced to implement the crack detection in hydraulic concrete structures. The experimental and theoretical investigations on bending loss and time-domain reflection behaviors of optical fiber are performed. According to the bending loss mechanism of optical fiber, the monitoring method of hydraulic concrete crack is presented. First, the effect of optical fiber bending radius on optical loss is analyzed. The mathematical model between bending radius and optical loss is established. Then, the identification principle of concrete crack using bending loss data of optical fiber is studied. Considering the crack characteristics of hydraulic concrete structure, the arrangement forms of optical fiber, which are used to monitor the tension crack and hybrid crack in hydraulic concrete structure, are proposed. Finally, the relationship between crack development and optical loss is investigated using laboratory experiments with optical fiber.

Keywords

hydraulic concrete structure, crack, detection method, bending loss behavior of optical fiber

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