Investigation On Bond-slip Relationship Between Corroded Steel Bars And Concrete Under Cyclic Loading

Corroded steel bars not only reduce the effective cross-section, but also reduce the bondproperties between steel bars and concrete. The structures which suffer accidental loads stillneed to resist the load including earthquake after rust. Therefore, it is very important to studythe bond properties of corroded reinforced concrete members under cyclic loading, and toestablish the dynamic analysis of bond-slip constitutive relationship for corroded reinforcedconcrete structures in service under cyclic loading. From the bonding aspects, the effects ofsteel bars’ types and corrosion rates were studied in this paper. According to the test results,the bonding mechanism of corroded reinforced concrete was explored under cyclic loading，and numerical fitting was made to fit the data of bond-slip. Based on the experimental data,the bond-slip constitutive relationship between corroded steel bars and concrete under cyclicloading was established.The main research work was as follows:1. The bond-slip curves of corroded reinforced concrete under cyclic loading werecarried out. The parameters included corrosion rates and the types of steel bars. Test resultsshow that the ultimate bond stress between concrete and smooth steel bars increases with thecorrosion rate when the corrosion rate is between2.16%~4.22%; But the stress was decreasedwith the corrosion rate increased, when the corrosion rate is between4.22%~8.17%; the bondproperties of concrete and ribbed steel bars were decreased with the corrosion rate increased,when the corrosion rate is between3.76%~12.85%%,and the bond properties of ribbed steelbars are better than smooth steel bars. The bond properties maximum degradation of smoothsteel were occurred in the cycle after the ultimate bond stress slip under cyclic loading, whilethe maximum degradation of ribbed steel occurred in the loop of concave and convex.2. On the basis of the tests results, the influences of reinforcement types, componentcorrosion rate on the bond strength were analyzed. After fitting the bond-slip curves bymathematical statistics, the parameters which can better identify the extent of corrosion and rust were expressed. The constitutive relationships between the corrosion steel bars and theconcrete under cyclic loading were established. Research result will provide the basic dataand model for the stress analysis between corroded reinforced concrete elements orstructures.