A novel retrofit technique for strengthening steel columns using FRP

Fiber reinforced polymers (FRP) are commonly used to repair and/or retrofit concrete and masonry structures. However, compared to concrete and masonry structures the use of FRP for retrofitting steel structures, particularly members such as steel columns and connections, has been limited. This paper investigates a novel retrofit technique to strengthen l-shaped steel columns, through a set of experimental tests on short columns. The proposed retrofit technique involves wrapping the steel column with FRP and filling the voids between the FRP and steel with concrete. In this study, the fiber reinforcement is oriented in the lateral direction to confine the concrete core. Experimental findings including increased load carrying capacity, stiffness and ductility confirm the effectiveness of this proposed technique. A finite element model was developed to analyze the response behaviour of a steel column retrofitted using this proposed technique. Stress distribution contours determined from the finite element analysis of the columns show the unique confinement mechanism.