Performance-based assessment of seismic-resilient steel moment resisting frames equipped with innovative column base connections

Many recent research studies have focused on developing innovative seismic-resilient structural systems to reduce repair costs and downtime in the aftermath of an earthquake. In this regard, dealing with steel Moment Resisting Frames (MRFs), recent research works have demonstrated the benefit deriving from the adoption of both low-damage and self-centring column base connections, both in terms of damage and residual drifts reduction. Although several technologies have been developed in this direction, only a few research studies investigated the significant parameters influencing the self-centring capability of these systems. Within this framework, the present study investigates the influence of the frame layout (i.e., storeys and bays number) on the seismic performance, including the self-centring behaviour, of perimeter MRFs equipped with damage-free self-centring column bases previously studied by the authors. Nine case-study perimeter steel MRFs are designed and modelled in OpenSees. Incremental Dynamic Analyses are performed with a set of 30 ground motion records while monitoring both global and storey-level engineering demand parameters, including peak and residual interstorey drifts. Fragility curves are successively used to evaluate the self-centring capability of the structures. The present study provides insights on the use of the adopted connections for the residual drift reduction of MRFs and defines the boundaries of the investigated parameters for their application. Results highlight that the self-centring behaviour is particularly sensitive to the number of storeys and tends to reduce with the increasing height of MRFs equipped with the proposed connections.