In this paper, combining with the tenth anniversary load test of Sutong Bridge, we proposed the Brillouin Optical Time Domain Analysis (BOTDA) to conduct health monitoring research on the bridge, and completed the following three aspects: Firstly as an auxiliary measure of strain monitoring, monitor the level of stress and strain along the longitudinal bridge to each position. Secondly through the parking of the vehicles at different positions on the bridge pavement, the influence lines on the overall structural stress of the bridge are obtained. Thirdly through the long-term strain monitoring of the bridge, the impact of the usual traffic load information on the bridge strain is obtained.The results show that the technology not only breaks through the monitoring bottleneck of traditional point sensors, but also realizes distributed measurement of strain on the transmission path; it can also be used for real-time monitoring, damage identification, crack location, settlement monitoring of traffic load information of bridges and other structures.. Compared with the traditional sensor test results, the effectiveness and frontier of the technology are proved, and the significance of the distributed fiber-optic sensor technology for the health monitoring of major structures such as bridges is fully explained.
In this paper, Brillouin Optical Time Domain Analysis (BOTDA) is proposed to solve the problem that the traditional point sensor is difficult to realize the comprehensive safety monitoring of bridges and so on. This technology not only breaks through the bottleneck of traditional monitoring point sensor, realize the distributed measurement of temperature and strain on a transmission path; can also be used for bridge and other structures of the damage identification, fracture positioning, settlement monitoring. The effectiveness and frontier of the technology are proved by comparing the test of the indoor model beam and the external field bridge, and the significance of the distributed optical fiber sensing technology to the monitoring of the important structure of the bridge is fully explained.
In this paper we propose a low-cost and stable configuration of Brillouin Optical Time Domain Analysis (BOTDA). Both pump and probe are generated by one single laser source for steady frequency beating. Polarization-maintaining modulators and amplifiers have been applied into the system in order to suppress the ground noise and to control the stability of the pump pulse. The probe is filtered and amplified to obtain the Stokes wave. The bias voltages of modulators are carefully controlled. We implement the prototype of interrogator by using this method and compare it with commercial products. The result shows that the long-term stability of the prototype is three times higher than that of commercial product.