Parametric analysis of steel MRFs with self-centring column bases

Nominated for Eurosteel 2021 Best Paper Award. In recent decades, innovative seismic-resilient structural systems have been proposed to reduce the direct and indirect losses related to seismic events. Among others, steel moment-resisting frames (MRFs) equipped with damage-free self-centring column bases (SC-CBs) represent a promising solution. Although several configurations of SC-CBs have been proposed in literature, only a few research studies investigated how the significant parameters (e. g. number of storeys, frame layout, seismic mass, seismic intensity) affect the seismic performance of MRFs with SC-CBs. To further investigate this aspect, the present work focuses on the influence of an additional parameter (i. e. the combination of seismic mass and acceleration) on their self-centring capability. Three 5-bay steel MRFs with 4, 6 and 8 storeys are considered as case-study frames and designed based on two different values of the seismic mass (i. e. M1 and M2). Numerical models are developed in OpenSees, incremental dynamic analyses (IDAs) are performed to monitor global engineering demand parameters (EDPs), and fragility curves are derived to evaluate the seismic performance of the structures. It is observed that the inclusion of SC-CBs produces beneficial effects in terms of increased self-centring capability on all the investigated case studies. Moreover, the parametric analysis allows some preliminary observations to be drawn regarding the influence of the number of stories and seismic mass.