Study On Damage Detection Based On Quasi-distributed Long-gage Fiber Grating Sensor

With a number of massive projects structural of the aging and a number of massive projects construction, once these structure failure, will lead to huge economic losses and casualties. It has important and practical significance to establish a complete set of health monitoring system for these massive projects structural. Damage detection is one of core technology for structural health identification. Although, developed a variety of damage identification methods. Accurately measure the response of the structural information is the premise of the effective of damage identification. Damage is exist into the structural can not be predicted, so it is not advisable for Health Monitoring by means of strain gauges. Therefore, Fiber Bragg Grating (FBG) sensor is put forward in this background, and become one of the most hot research of the Structural Health Monitoring(SHM). In this paper, built a FBG monitoring system for test research. Details are as follows:(1) State the research background significance, overseas and domestic research about FBG in Health Monitoring and FBG application in engineering practice;(2) State the damage identification methods and basic principle of FBG;(3) Study on damage location of steel beam based on long-gage FBG sensor; the experimental results show that the long-gage FBG strain sensor farther away from the damage position of the measured strain value change is smaller, the long-gage FBG strain sensor measured range have certain restriction, if full arrange FBG strain sensor on the site prediction, which can solve this problem; For an elastic member, circular hole has certain influence on measured value of FBG strain sensor, although FBG strain sensor is influence adjacent damage parts, strain sensor can effectively damage fore-warning, damage location; except estimate damage degree of bending stiffness;(4) Study on damage detection and deflection measurement of composite beam based on long-gage FBG sensor; Arrange quasi-distributed long-gage bare FBG strain sensors on the surface of the upper and lower flange of composite beam. Firstly, the neutral axis of the cross section can be located by macro-strain that detection any damage. Secondly, obtain the local curvatures of each cell. From these local curvatures, one may obtain a curvature equation for the section by fitting a polynomial through the values produced in each cell, the curvature expression for each section is integrated twice to produce the deformed shape...