A large amount of buildings and infrastructures in the world are reinforced concrete (RC) frame structures designed prior to the entry into force of seismic guidelines and seismic detailing rules. Seismic risk associated with these structures is significant due to their low lateral load-carrying capacity and insufficient ductility. In particular, RC columns play a critical role to the seismic performance, being the location of most of the structural deficiencies (poor concrete, inadequate transverse reinforcement, lack of seismic details). One of the extensively used retrofitting technique for columns is the steel-jacketing. It consists of the installation of a cage made of steel angles and battens providing additional confinement and transverse reinforcement to the RC elements,and compensating their ductility lack.