Parameters affecting the behaviour factor and the seismic safety of EC8-designed reinforced concrete buildings

Currently, Eurocode 8 allows a force-based design and safety assessment of buildings accounting for their inelastic displacement capacity by means of a force-reducing factor named behaviour factor. The value of the behaviour factor for new buildings depends on the structural typology, on the structural regularity and on the ductility class of the building. However, recent studies showed that the use of an equal behaviour factor for structures realized in zones characterized by different seismicity fails in providing such structures with the same risk level. Therefore, to achieve this goal, to which the next generation of Eurocodes seems to be oriented within a more refined performance-based design approach, it is necessary to evaluate hazard-dependent risk-targeted behaviour factors for new structures. In this study, non-linear static analyses are performed on reinforced concrete buildings designed according to Eurocodes and different for design seismic acceleration and number of storeys. This allows the post-design evaluation of the case-study buildings' behaviour factor. The potential dependency of the behaviour factor from different design parameters, namely the number of storeys of the structure and its design seismic acceleration, is investigated and discussed. Preliminary evaluations on the possible modifications of the currently-applied behaviour factors aimed at obtaining the same risk level for the case-study structures are presented and discussed. All the above results are obtained and compared by adopting different modelling approaches for RC elements.