A REVIEW OF DIRECT FASTENING STEEL JACKET FOR STRENGTHENING OF REINFORCED CONCRETE COLUMNS

Abstract

A novel retrofit method for reinforced concrete (RC) columns using a direct fastening steel jacket has been newly developed. This novel retrofit method features a simple and quick retrofit procedure, whereby high-strength fasteners are actuated and driven through to connect steel angles, steel plates and the concrete surface surrounding the column. Steel plates in direct fastening steel jackets can carry axial load and lateral load directly because they are appropriately interacted with RC columns. Direct fastening connections in direct fastening steel jackets behave in the manner of transverse reinforcement, which can share shear load and generate passive confinement to concrete columns. Given that limited research has been undertaken on direct fastening steel jackets, this paper summarizes state-of-the-art work on the experimental study, theoretical study and design methods of direct fastening connections used to strengthen RC columns. Interesting findings include the significant improvement of the strength and flexural stiffness of RC columns strengthened by the developed method and subjected to axial and cyclic lateral loads, as observed in experiments. Furthermore, the theoretical study based on fundamental mechanical derivations lays down the groundwork for the development of the design methods of RC columns strengthened by this innovative method.