Research On Optical Fiber Sensing Technology And Its Application To Model Test

Compared with the traditional sensors, the optical fiber sensors are credited with promising sensing alternatives for several advantages such as immunity to electromagnetic interference, light weight, small size, multiplexing capabilities, ease of installation and durability. Optical fiber sensing technology, which develops on the basic of optical fiber sensors, has already been widely used in civil engineering, especially in structural health monitoring. The main points of this dissertation are to present the new applications of the optical fiber sensing technology. The layout of the paper is as follows:The chapter 1 is the introduction of the importance and components of structural health monitoring. The sensing principle of optical fiber and the application of it are presented. In addition, this chapter illustrates the main research content of dissertation.In chapter 2, the commonly used methods to detect broken strands faults of high-voltage transmission line and its practical problems are presented. A new method of detecting broken strands faults of high-voltage transmission line based on optical time domain reflect meter technology was put forward. In this chapter, the theory of testing with OTDR is introduced at first, and then the research work focuses on the model experiment, in which the steel tube was used to simulate the high-voltage transmission wire, and the prototype experiment was carried out. The results of the experiments demonstrate that this detecting system can discriminate high-voltage transmission wire broken strands faults accurately.In chapter 3, the sensing principle of Fiber Bragg grating (FBG) sensors is explained at first, and the strain transferring character is conducted in the calibration experiment on the steel plate using universal testing machine, then the research work focus on the crack measurement of the prestressed plate by using the FBG strain sensor with reduced sensitivity. In a series of different working loading experiments, the data measured by FBG sensors are collected throughout a commercial FBG wavelength interrogation system. The comparison of FBG sensor and traditional measurement reveals that the FBG sensors can be an effective way to measure the crack of the prestressed concrete.