The Research On Monitoring Technique Of Steel Corrosion Using Fiber Optic Sensor

Reinforced concrete structure is one of the most widely used structures in civil engineering.Premature destruction of concrete structures caused by steel bar corrosion has become a highlight of the world and grown a big disaster.And it is sufficiently significant to keep abreast of reinforcement corrosion state in time.In this paper,present condition of steel corrosion monitoring in concrete structures is reviewed firstly.Then,direct monitoring technique of steel corrosion based on optical fiber sensing is put forward.For this purpose,a number of researches are conducted in this dissertation and the achieved results are as follows:1.The importance and urgent situation of steel corrosion monitoring in concrete structures is illustrated in this paper.Then,all kinds of existing monitoring techniques are summarized and analyzed and the problems in them are pointed out.2.Based on the fact that bond property between steel bar and concrete changes in rusted areas,a new concept to monitor steel corrosion is presented by the change of stress and strain of the rebar and its surrounding concrete after steel corrosion.By analysis of the relationship between steel corrosion and strain,the principle and method of corrosion monitoring according to the concept above is given.3.The principle and performance of the common distributed sensing technology is introduced in detail.From the needs of corrosion monitoring,PPP-BOTDA optical fiber sensing technology is chosen for distributed strain monitoring.After that,some technique problem is discussed,including accuracy of strain measurement,the layout of fiber optical,cross-sensitivity of temperature and strain of PPP-BOTDA.4.Monitoring the strain of reinforcement concrete simple beams applying distributed fiber optical sensing and traditional strain gage respectively,and verifying the validity of the strain of reinforced concrete structure by PPP-BOTDA system.5.The study tested part corrosion of reinforcement concrete beams,verified the feasibility that PPP-BOTDA distributed fiber optical sensing can be used to monitor steel corrosion real-timely,nondestructively and distributed,and obtained the practical method of steel corrosion identification.