Multi-scale load identification system based on distributed optical fiber and local FBG-based vibration sensors

Abstract Deformation and stress are the most important parameters for structural damage identification, but the sensors used for structural deformation or stress monitoring cannot be effectively installed on the pipeline with insulation layer, highway, railway and other service structures. In this case, the unfavorable load identification is of great significance for the damage assessment of large-scale structures. The distributed optical fiber vibration sensor (DOFVS) can realize continuous vibration monitoring for tens of kilometers, but the identification accuracy of vibration load is vulnerable to environmental vibration interference and the local position accuracy is not high. In this paper, one multi-scale load identification system based on distributed optical fiber and local FBG (fiber Bragg grating)-based vibration sensors are developed for solving this problem. In this system, the local FBG-based acceleration sensors (also known as FBG-based vibration sensors) are arranged in the area prone to adverse vibration loads for high precision measurement. The distributed optical fiber vibration sensors are continuously deployed in the structure for full scale measurement. In order to verify the feasibility of the load identification system, a field load identification test is carried out, and the distributed optical fiber vibration sensor and the FBG-based acceleration sensor are compared for use to monitor the vibration signals caused by different types of vibration loads. Test results show that the FBG-based acceleration sensor belongs to fixed-point positioning, the distributed optical fiber vibration senor belongs to large-scale positioning, and the vibration responses of the two sensors have good consistency.