RINTC project: nonlinear dynamic analyses of Italian code-conforming reinforced concrete buildings for risk of collapse assessment

This paper reports on the results of an ongoing Research Project aimed at computing the risk of collapse in code-conforming new Italian buildings. A companion paper describe the overall Research Project ([11]), funded by the Italian Civil Protection Department (DPC), its different areas of application (reinforced concrete, masonry, steel buildings, etc), the overall seismic risk calculation procedure and the ground motion selection process for the recorded ground motions used for the multi-stripe analyses. This paper deals with different classes of reinforced concrete buildings (namely 3-, 6- and 9- story high moment resisting frame) designed in cities with increasing seismic hazard. For the sake of brevity, only the results of 6-story buildings are reported. First, the paper describes the geometry, material characteristics and main design properties of the buildings, including their elastic dynamic properties. Three different configurations are considered: Bare Frame (BF), Infill Frame (IF) and Pilotis Frame (PF, that is a building with infills at all levels except for the ground level). Design of the first two configurations is identical, while the PF requires an increase in the design forces at the ground level. Second, the paper introduces the nonlinear models used for the nonlinear analyses: lumped plasticity models for beams and columns, strut and tie models for the infills. Since the buildings are designed according to capacity design principles, the nonlinear behaviors of beams and columns in shear and of beam-column joints are not considered. Pushover analyses are used to estimate the EDP (top floor displacement) value used for the definition of the collapse limit state. Finally, the results of the multi-stripe analyses are presented for ten different ground motion intensities.