A Pitman Style Fiber Bragg Grating Displacement Sensor Based on Wedge Cavity Structure

In this paper, a new design of fiber Bragg grating (FBG) displacement sensor is presented based on wedge cavity structure. A new type of pitman FBG displacement sensor with a simple structure, small size and anti-electromagnetic interference is invented. Calibration of the FBG displacement sensor is carried out. The calibrating data shows that the sensitivity is 5.58 pm/mm, adjusted R square is up to 0.99 and the static error is 5.168%. Moreover, the FBG displacement sensor is applied in the hysteresis test of steel frame-reinforced concrete infill wall. The monitoring results from the FBG displacement sensor in this test match well with the resistance strain displacement meter, to prove the FBG displacement sensor with a good accuracy. It is also showed that this new FBG displacement sensor produces smaller influence on the structure, and it is suitable for long-term displacement monitoring of engineering structures.