Effective placement of self-centering damage-free connections for seismic-resilient steel moment resisting frames

In recent years, significant advancements have been made in the definition of innovative “minimal-damage structures,” chasing the need for more resilient societies against extreme seismic events. In this context, moment resisting frames (MRFs) equipped with self-centering damage-free (SCDF) devices in column bases and beam-to-column joints represent a viable solution to improve structural resilience and damage reduction. However, the extensive use of these devices significantly increases complexity and costs compared to conventional structures, thus limiting their practical application. To overcome this drawback, current research works are focusing on the definition of effective placement for SCDF devices, maximizing their beneficial effect on the seismic response and controlling their impact on the overall structural complexity. Within this context, the present study investigates the influence of the placement of SCDF devices in a steel MRF. An eight-story MRF is designed, and 50 configurations with different locations of SCDF joints are considered. Numerical models are developed in OpenSees, and non-linear static push–pull and incremental dynamic analyses (IDAs) are carried out. The influence of the placement of SCDF devices is assessed by considering residual and peak interstory drifts, residual top story drifts, peak story accelerations, and the total dissipated energy as performance parameters. The results of IDAs for a seismic intensity corresponding to the ultimate limit state (ULS) are analyzed and compared, and fragility curves are successively derived for some relevant configurations. The paper provides insights and observations to understand how including a different number of SCDF BCJs at different stories affects the seismic response.