Study On Fibre Grating Corrosion Sensor And Corrosive Expanding

One of the most concerned issues in civil engineering is currently durability of reinforced concrete structure.The lack of durability of concrete may lead to an early failure before designed service life reaches.A new construction or reconstruction of these failed reinforced concrete structures have brought huge losses to our economy.So the durability of reinforced concrete structures is an urgent and significant problem.Corrosion of steel bars is the vital cause of concrete structures' failure.Corrosion of steel bars,causing the crack of concrete protective layer and degradation of steel bar's mechanical properties deteriorate.The bond between steel and concrete decreases,ultimately reducing structural durability and shortening the service life of concrete structures.It is helpful to evaluate the durability of reinforced concrete structures by the real-time monitoring of the corrosion state of steel reinforcement and the study of the theory of steel reinforcement corrosive expansion.In this paper,basing on chloride ion erode steel bars and cause corrosion of steel bars,it provides some references for the durability research of reinforced concrete structure by the theory of reinforcemen corrosion expansion of concrete protective layer cracking caused by steel bar corrosion and the real-time monitoring of concrete corrosion state through theoretical analysis,experimental research and numerical simulation.The research contents are introduce:(1)Mechanism of steel bars corrosion is introduced,focusing on the influence of chloride ions on steel bar corrosion.The research status of corrosion sensors of fibre Bragg grating and the theory of steel corrosion expansion are summarized.At the same time,the advantages and disadvantages of traditional detection methods and optical fibre corrosion sensors were stated.(2)The principle of fibre Bragg grating sensor is analyzed.Effect factors of fibre grating wavelength variation are discussed.Based on colume expansion,a formula of corrosion rate based on strain variation after steel bar corrosion is given.(3)Based on the elastoplastic mechanics,formulas of the steel corrosive expansion force and the displacement of the inner edge of the concrete are given for all stages including free expanded rust,initial cracking and cracking propagation.(4)The corrosion state of steel bars is monitored by a temperature compensated fibre Bragg grating sensor.The corrosion process of reinforcement is analyzed and the performance of sensor is evaluated.Experiments of different groups are designed to verify the correctness of the theoretical model,and the theoretical model and experiment are combined to better reflect the monitoring function of fibre Bragg grating corrosion sensor.(5)The finite element analysis software ANSYS is used to simulate the uniform corrosion of the steel bar in concrete.Basing on the result,which can verify the theoretical model of rust expansion and the effectiveness of fibre Bragg grating corrosion sensor.