Research On The Process Of Corrosion Damage Of Reinforced Concrete Based On Acoustic Emission

At present,the problem of durability caused by corrosion of reinforced concrete structures around the world is increasing.Corrosion of steel bars will not only reduce the adhesive force between steel bars and concrete,but with the progress of corrosion,the accumulation of corrosion products will produce corrosion expansion force,which will cause cracking and peeling of the cover of concrete,and induce structural durability issues.Therefore,the research on the corrosion resistance of reinforced concrete such as the corrosion damage assessment of steel bars and the structural health monitoring has become a major subject,which has important engineering practical significance.This article starts from the theory of damage caused by corrosion of steel bars.Based on acoustic emission technology,the whole process of corrosion damage of PVA fiber reinforced concrete and ordinary reinforced concrete is tested and simulated.The main research work and results are as follows:(1)Based on the theory of damage caused by rust in steel bars,this paper analyzes and refines the corrosion deterioration process of steel bars,and studies the corrosion expansion force calculation models under different theories.It was found that the overall results of the corrosion expansion force calculation model were consistent,but the results of the corrosion expansion force calculation model based on elastic-plastic theory were generally large,while the corrosion expansion force calculation model based on the fracture theory was generally small and closer to the theoretical value.This paper also analyzes and studies the main methods of calculating the corrosion rate of steel bars.(2)Use acoustic emission technology to conduct accelerated corrosion test on PVA fiber reinforced concrete and ordinary reinforced concrete under full immersion environment.Through the analysis of acoustic emission parameters,the whole process of concrete corrosion-induced damage was refined into five stages,and the relationship between the acoustic emission signal and the actual degree of corrosion of the steel bar was determined.The swell relationship between acoustic emission signal parameters and PVA fiber reinforced concrete is given.The swell relationship between acoustic emission signal parameters and ordinary reinforced concrete is also given.The spectrum characteristics of different damage stages were obtained by using the spectrum analysis of acoustic emission signals.With reference to the margin index,the corrosion-induced damage process of PVA fiber-reinforced concrete was evaluated,and the evolution process of corrosion-induced damage to steel bars was established with the margin curve as the evaluation standard.The influence of PVA fiber on the cracking of reinforced concrete was determined,and the optimal fiber content for the corrosion resistance and durability effect of the fiber concrete structure was found.(3)Using ANSYS finite element software analysis,the feasibility of finite element analysis of corrosion-induced damage process of reinforced concrete is verified.At the same time,it was found that adding appropriate amount of fiber to concrete can improve the tensile properties of concrete and delay the cracking of concrete.When the load of the concrete exceeds its ultimate tensile strength,the interface between the steel bar and the concrete cracks first,which is consistent with the actual engineering cracking situation.