Comparative Analysis of the Impact of Vertical Irregularities on Reinforced Concrete Moment-Resisting Frame Structures According to Eurocode 8

Eurocode 8 is undergoing a revision process encompassing novel ductility classes, damage limitation limits, local ductility conditions corresponding to detailing prescriptions and structural irregularity criteria. In this paper, we specifically assessed the influence of an irregularity in elevation, imposed by different elevations, on the first and third storeys of buildings, and variations in the cross-sections of columns during the seismic response of reinforced concrete (RC) structures. To assess this impact, an extensive examination was conducted on thirteen five-storey moment-resisting frame (MRF) buildings. The design of those structures was carried out on the Robot Structural Analysis Professional framework following the current generation of Eurocodes 2 and 8, and the seismic response analysis was carried out using the SeismoStruct v2024 software. The results were compared to evaluate the influence of imposed irregularities in elevation due to the increasing height, column cross-section, mass, and resistance variation. The study’s outcomes revealed that, for DCM structures, the imposed irregularities in elevation have different impacts on the seismic response. Increasing the heights of ground or middle floor have substantial deleterious effects on the building’s seismic response. The planned geometry and variations in the cross-sections of columns substantially impact inter-storey drift and base shear. The effects of mass and resistance irregularities were neglected in this study. As such, more studies on those matters are necessary to allow our results to be further generalised.