Measurement technique based on the FBG-BOTDA(R) for Infrastructures

There are disadvantages of current distributed strain monitoring technology, such as low accuracy and spatial resolution, low sampling frequency, and large cost. Single-point strain measurement technique with high-precision cannot cover the damage features of structures of large span, long distance, large deformation and hidden location, and the cost of installation of the sensors takes up a big proportion of structural health monitoring system. An integrated system of distributed full-scale and local monitoring technique with single optical fiber is developed by combing the Brillouin distributed sensing technology with local high-precision optical fiber Bragg grating (FBG) technology. A high-strength and durable strain cell based on this concept, without weakness, is also produced, named as Fiber Bragg Grating-fiber-reinforced polymer(FRP-OFBG). Experiments of a reinforced concrete beam under three-point bending and a full scale cable are carried out to verify the effectiveness and the advantages of the integrated system. The result indicates the integrated system can be used for monitoring of large-scale, complex and long-span structures.