Effect of steel wrapping jackets on the bond strength of concrete and the lateral performance of circular RC columns

In this study, the bond behavior between steel reinforcing bars and concrete confined via steel wrapping jackets is estimated. Lateral bending tests are conducted for the reinforced concrete columns with continuous longitudinal reinforcement or lap-spliced longitudinal bars confined by the steel wrapping jackets. It is found that the jackets increase the bond strength and ductile behavior due to the transfer of splitting bonding failure to pull-out bonding failure. In the column tests, the steel wrapping jackets increase the flexural strength and ultimate drift for the lap-spliced column. However, the jacket for the column with continuous longitudinal reinforcement only increases the ultimate drift since the flexural strength depends on the yield of reinforcement. Finally, this study suggests a basic concept for determination of the thickness of the steel wrapping jackets which is different from the conventional method.