Flexural Behavior of Columns Strengthened Using Reinforced Concrete Jacket with Seismic Details

The primary objective of the present study is to examine the effectiveness of previously developed prefabricated bar units with seismic details in the jacket section in improving the flexural performance of columns jacketed with reinforced concrete (RC) sections. One non-seismic existing column, two bonded-type laminate-jacketed columns, and six RC-jacketed columns were tested under constant axial load and cyclic lateral loads. The flexural strength of the columns was examined by comparing with predictions obtained using the ACI 318-14 procedure and nonlinear section lamina analysis considering the confinement effect provided by the jacket. The flexural ductility of RC jacketed columns was assessed by using the work damage indicator and the performance-based approach proposed by Sheikh and Khoury for seismic virgin columns. The test results revealed that the proposed RC jacketing approach using prefabricated bar units has the potential to enhance the flexural stiffness, strength, and ductility of deficient columns by providing a reliable confinement. The flexural capacity of jacketed columns can be conservatively estimated by the ACI 318-14 procedure and predicted more accurately by the section lamina analysis. In addition, RC-jacketed columns with prefabricated bar units can be designed to possess moderate ductility performance by adjusting the amount of transverse reinforcement in the jacketed section. Keywords: columns; ductility; flexural capacity; jacketing; prefabricated bar unit.