RETROFITTING RC FRAMES WITH A NOVEL COMPRESSION RELEASE BRACING SYSTEM

Steel bracing is known to be one of the most effective systems in resisting lateral loads. It is widely used for steel structures and starting to gain popularity among Reinforced Concrete (RC) structures. The ability of this system to resist lateral loads is usually governed by the buckling load of the compressive brace member, resulting in a system with a limited ductility. Following an earthquake, replacing damaged brace members requires significant amount of time and effort. Innovative lateral load resisting systems that reduce the damage during strong earthquakes and lessen the post-earthquake retrofitting time are therefore needed. In this paper, two braced RC frames with different bracing sections are initially tested under reverse cyclic loading to gain additional understanding about the behaviour of RC braced frames. An innovative tool that releases the compressive force in the brace members is developed. Two different designs of this tool were installed in the bracing members of two additional specimens. Cyclic testing of these specimens indicated that this tool would lead to a favourable seismic performance. It effectively removes the buckling failure mode from the response and enhances the ductility of the brace-frame system by providing an adequate capacity for energy dissipation.