Seismic design of reinforced concrete frames by including the confinment

This work presents a proposal to include the confinement effects in the seismic design of a reinforced concrete frame, within the framework of the capacity design. In detail, a comparison in reliability terms is carried out between a RC frame designed according to the current codes (i.e., the Italian code and the Eurocode), and the same frame designed considering the confinement. In addition, different constitutive models for the confined concrete are investigated for the reliability comparison. Thus, different fiber models are numerically defined, considering many seismic records, scaled according to increasing seismic intensities. Hence, nonlinear incremental dynamic analyses (IDAs) have been elaborated, considering the interstory drift indices as engineering demand parameters to achieve the lognormal fragility curves. Finally, the seismic reliability curves have been computed showing that the influence of the confinement on the seismic performance.