Seismic Performance of Existing RC Structures retrofitted with Hysteretic Devices

Hysteretic devices represents one of the best techniques for retrofitting or upgrading the numerous existing reinforced concrete framed buildings in areas with high seismic hazard. These passive control devices are usually installed in braces that are connected to the existing structures with the purpose of increasing their stiffness and providing additional energy dissipation capacity. This study deals with the influence of masonry infill walls on the performance design and assessment of buckling restrained braces (BRBs) for building seismic retrofit. First, an advanced nonlinear three-dimensional model of an existing building in L’Aquila is developed in OpenSees, by accounting for the effect of infill walls, and a widely employed procedure based on pushover analysis is employed to design the braces, by controlling the maximum inter-storey drift under the design seismic input. Subsequently, the seismic performance of the retrofitted buildings is checked by performing both nonlinear static analysis and incremental dynamic analysis under a set of real ground motion records. The study results demonstrate the effectiveness of the design procedure and shed light on the influence of the infill walls on the performance of the system retrofitted with BRBs.