Seismic retrofit of bridge columns using innovative wrapping technique

This analytical work focuses on enhancing the seismic performance of reinforced concrete (RC) bridge columns by using innovative active confinement technique. Although the passive confinement approach has been widely accepted and used, research has shown that better results could be obtained by applying external confining pressure on the concrete element; a technique that has been widely known as active confinement. The approach proposed in this paper focuses on exploring the concept of using rings made of Shape Memory Alloys (SMAs) in providing active confinement The shape recovery phenomenon of SMAs is utilized to apply the external confining pressure without the need for excessive hardware or labor. An analytical model of a bridge column is developed and analyzed. A comparison is conducted between the cyclic behavior of the column when retrofitted using the proposed technique and the passive confinement approach using carbon fiber composite wraps. Two constitutive models are used to describe the stress-strain behavior of the confined concrete using the two techniques. The results show a significant improvement in the ductility capacity associated with less level of damage in the columns retrofitted using the proposed SMA rings compared to the fiber composite wraps.