A Look at the seismic risk of Italian code-conforming RC buildings

This paper discusses the seismic risk of some structures designed, modeled and analyzed within the RINTC (Rischio Implicito di strutture progettate secondo le Norme Tecniche per le Costruzioni) project. RINTC, funded by the Italian Department for Civil Protection is a multiple-year effort that started in 2015 as a joint collaboration between ReLUIS (Rete dei Laboratori Universitari di Ingegneria Sismica) and EUCENTRE (Centro Europeo di Formazione e Ricerca in Ingegneria Sismica). In the project, the structures, with a variety of structural types, configurations and locations, spanning a wide range of seismic hazard levels, were designed in compliance with the current Italian code provisions, while their seismic risk was computed, in terms of annual failure rate, following the framework of performance-based earthquake engineering. The results of RINTC, although not yet fully consolidated, show, among other features, a generally increasing trend of the annual collapse rates with the increasing hazard of the sites. This study, aiming at investigating the preliminary results of RINTC, examines structural response to gather insights on the homogeneity of the collapse risk among the prototype buildings. In particular, the reinforced concrete moment-resisting frames are examined using single-degree-of freedom systems equivalent to the detailed structural models, in order to capture the overall tendencies of their seismic behavior. It appears that the increasing trend of the failure rates with site hazard is reflected in the actual strength reduction factors of the equivalent systems, despite the uniform value of the behavior factor was set to define the reference design strength of the buildings.