ADVANCED MODELLING AND RISK ANALYSIS OF A RC BUILDING EQUIPPED WITH ENERGY DISSIPATION DEVICES DESIGNED BY THE ITALIAN SEISMIC CODE

Among the modern techniques envisaged to improve the seismic performance of structures there is energy dissipation, which consists in dissipating part of the seismic input energy by means of special devices, i.e., the dampers, which are not part of the structural frame supporting gravity loads. Energy dissipation systems are typically designed to provide structural safety at the Life Safety ultimate limit state, but at the same time they are required, according to current Seismic Codes, to resist to earthquakes of higher intensity, corresponding to the case of Non-Collapse Limit State. However, the literature is missing of studies about the behavior of structures equipped with damped braces under collapse condition. In this contribution, an existing RC structure is retrofitted for a high seismicity area using steel braces equipped with hysteretic devices. Non-linear dynamic analyses are carried out considering two sets of bidirectional natural ground motions, correspondent to the Life Safety Limit State (LLS) and Non-Collapse Limit State (CLS). The aim of the research is to identify critical aspects of the retrofit design and to provide the basis for the computations of the implicit risk of the seismic collapse of the retrofitted structure and of the local failure of the dampers.