Experimental Study On Bond Behavior Of Corroded Ribbed Reinforced Bar And Concrete Confined With Stirrups

Concrete structure is a kind of building material widely used in the world,under normal and reasonable use conditions,the good cohesiveness between the reinforcement and the concrete can make the performance of the component fully exerted.However,many reasons such as carbonization and chloride corrosion of concrete cause corrosion of reinforcing bars in concrete,and structural bond is destroyed.Therefore,the research on the bond properties of corroded components is very important in guaranteeing the bond performance and durability of components.Scholars from all over the world have already carried out the related research on the effect of corrosion on the bond properties of reinforced concrete structures,and the research results are not uniform,at the same time,the study of small specimen is mostly not considering the restraining effect of the stirrup,which is quite different from the actual project.On the basis of the experiment and theory,the main contents of this paper are as follows:(1)Under the background of the problem of steel corrosion,the research contents and progress of corrosion bonding between different scholars at home and abroad were analyzed.According to the characteristics of the study on the confinement of the stirrup in this test,the rules of bonding in the related research,with or without the confinement of the stirrup are arranged,and the rule shows that the stirrup has a remarkable improvement on the bond performance.(2)Increasing the confinement constraint,the corrosion of reinforced steel in concrete structure is simulated by accelerated electrified corrosion,divided into 8 strength grades(C15,C20,C25,C30,C35,C40,C45,C50),4 kinds of corrosion degree(no rust,mild,moderate,severe),and 96 specimens,including 72 corrosion specimens.The bond slip relationship between ribbed bars under different corrosion rates and different concrete strength is obtained by drawing tests.(3)A formula for calculating the ultimate bond strength of corroded reinforced concrete is put forward considering the corrosion rate,the tensile strength of concrete,the thickness of relative protective layer,the relative anchorage length and the stirrup ratio.Compared with the experimental data,it is found that the formula has better fitting effect.At last,the bond slip curve of reinforced concrete after rust is analyzed.With reference to the existing bond slip formula,the new change factor corrosion rate and the strength of concrete are added,and the relation expression about the corrosion rate,slip value and bond strength is given.