1、Concrete structure inspection

    Concrete is an indispensable part of Bridges.  However, in the long service process of Bridges, concrete materials will produce cracks of different degrees under the influence of many factors.  According to the different degree of cracking, concrete crack can be divided into penetration crack and deep crack.  The occurrence of the through-crack will seriously reduce the bearing capacity of the bridge and directly threaten the overall safety of the bridge.  Therefore, in the internal damage detection of Bridges, strengthening the capture of ill-conditioned signals released by cracks can greatly ensure the safety of Bridges during use.  In concrete detection, the advantage of optical fiber sensor is that it can detect the whole structure of the bridge at the same time, and can adopt distributed detection method to avoid the problem of missing detection and missing parameters, and the detection data transmission is very stable.  The fiber optic sensor is easy to set up and operate, and can ensure that the properties and mechanical parameters of concrete are not affected.  

2、Vibration detection of bridge structure

    The working principle of optical fiber sensor in vibration detection of bridge structure is  , paste signal optical fiber on the structure surface or embedded within the bridge structure into the signal optical fiber, the bridge vibration occurs, signal optical fiber and synchronous vibration of the bridge structure of the optical signal changes in plants could also cyclical changes in the output light, detector receives the modulated signal light,  After the Fast fourier-Transform (FFT) system processing the vibration signals, the parameters of the whole or local vibration frequency and amplitude of the bridge can be obtained, so that the daily vibration detection of the bridge structure can be realized.  

3、Strain detection of bridge structure

    The strain in the bridge is one of the main parameters to evaluate whether the structure can be used normally.  According to the working principle of optical fiber sensor, the optical fiber sensor,  After it is installed in the initial position, effective labeling is carried out. The main function of labeling is to obtain the internal data relationship between the resistance chip sensor and the strain detector.  In the effective measurement of bridge strain, it is necessary to ensure that when the strain sensor is installed, violent impact, vibration impact and corresponding velocity impact with the surrounding environment are avoided. The relative humidity of the air is not more than 85%, the ambient temperature is 20 ℃ ±5 ℃, and the atmospheric pressure is about 1.05mpa.  Under this static standard, the calibration curve of the sensor can be obtained.  At present, f-P fiber sensor is mainly used to detect local stress of bridge structure, and fiber Bragg grating sensor is mainly used to detect distributed stress of bridge structure.  

    The optical fiber sensor on the bridge is connected to the optical fiber analyzer and connected to the bridge monitoring center through wired or wireless transmission, so as to diagnose the technical defects of the bridge in time.