Seismic retrofit of the student hall of residence of Messina through buckling restrained braces

This contribution describes a seismic retrofitting intervention designed and currently ongoing in the earthquake-prone area of Messina, Italy, where local strengthening techniques are combined with supplemental energy dissipation devices. This intervention concerns a 5-story building that represents the main student hall of residence of Messina. The structure is made of confined brick masonry in the first four stories, built in the 1930s, with an added fifth story together with a light appendage in reinforced concrete frame, built around 40 years later than the original masonry building. The building has a C shape in plan and exhibits moderate torsional effects, which are undesirable. Buckling restrained braces (BRBs) placed in selected frames of the structure have been adopted as dissipative elements to improve the seismic performance of the building. BRBs reduce torsional effects and increase the dissipation capacity of the building. Furthermore, to reduce the vulnerability of the last-floor reinforced concrete frame, pre-tensioned stainless steel ribbons are used in the beam-column joints of the last elevation, thus enhancing the confinement effect and inducing a beneficial precompression state that increases the ductility. The effectiveness of the retrofitting interventions is assessed through pushover analysis on the original and retrofitted structure comparatively. Acceptance tests on the employed hysteretic dampers carried out at the laboratory CERISI of Messina are also described.