Seismic performance of an existing RC structure retrofitted with buckling restrained braces

The use of buckling restrained braces (BRBs) represents one of the best solutions for retrofitting or upgrading the numerous existing reinforced concrete framed buildings in areas with a high seismic hazard. This study investigates the effectiveness of BRBs for the seismic retrofit of reinforced concrete (RC) buildings with masonry infills. For this purpose, an advanced non-linear three-dimensional model of an existing building in L’Aquila is developed in OpenSees, by accounting for the effect of infill walls through an equivalent strut approach, and by using a recently developed hysteretic model for the BRBs. The seismic performance of the building before and after the retrofit with BRBs is evaluated by performing both non-linear static analyses and incremental dynamic analyses under a set of real ground motion records along the weak direction of the frame. Seismic demand hazard curves are built for different response parameters before and after the retrofit, by accounting for and by disregarding the contribution of the infill walls. The study results shed light on the effect of the BRBs and of the infill walls on the seismic performance of the various components of the system, and on the effectiveness of the retrofit with BRBs for a real case study.