Seismic performance evaluation of a novel resilient steel frame with self-centering rocking columns and replaceable energy-dissipating connections for low-rise structures

To promote the seismic resilience of structures, minimizing both seismic damage and repair time is an effective way. Toward this goal, this paper proposes a novel resilient steel frame (RSF). The kernel structural components are the self -centering (SC) rocking columns and the replaceable energy -dissipating (ED) connections. The SC rocking columns equipped with shape memory alloy slip friction dampers (SMASFDs) reduce residual deformation and plastic damage of column bases, whereas the ED connections using shaped fuse steel plates mainly dissipate the input seismic energy. To demonstrate the seismic response characteristics, the numerical model of a three-story RSF is developed in OpenSees. The model is firstly validated by experimental results and then its seismic performance evaluations are carried out using three suites of earthquake ground motions associated with three seismic hazard levels. An equivalent conventional steel frame (CSF) with ED connections and rigid column bases is introduced as the counterpart. Incremental dynamic analysis (IDA) is conducted to obtain samples of the demand. Based on the IDA data, the joint fragility curves are generated using the joint probability density functions, taking into account the coupling relationship between the maximum and residual drift. The analysis results show that the RSF exhibits comparable maximum interstory drift and lower residual interstory drift, compared with the CSF. The introduction of the SC rocking column effectively protects the column from yielding and mitigates the residual deformation of the replaceable ED connections, therefore improving the reparability and seismic resilience of the structural system.