Seismic Performance of Reduced‐Strength Steel MRFs With SMA‐Based Superelastic Friction Dampers: An Experimental Investigation

ABSTRACT Shape memory alloys (SMAs) exhibit excellent self‐centering capability due to their stress‐induced phase transformation, making them highly suitable for applications in resilient infrastructure. This study investigates the seismic performance of reduced‐strength moment‐resisting frames (MRFs) equipped with SMA‐based superelastic friction dampers (SFDs). The SFD combines the high tensile strength and superelastic behavior of SMA cables with the high energy dissipation capacity of friction dampers. The performance of the SFDs is experimentally evaluated through real‐time hybrid simulation (RTHS) of a two‐story steel MRF building, outfitted with SFDs and designed for 0.75 and 0.5, where is the design base shear of a conventional MRF building. In the RTHS, the MRF is modeled numerically as the analytical substructure, while the SFDs installed at the first and second stories are physically tested in the laboratory as the experimental substructure. A series of RTHSs are conducted considering an ensemble of ground motions scaled to the design‐basis earthquake (DBE) and maximum considered earthquake (MCE) hazard levels. The seismic performance of the SFD‐equipped building is investigated in terms of global response, damage mitigation, and self‐centering behavior. The results demonstrate that the prototype structure maintains resilient seismic performance even when the design base‐shear capacity is reduced to 0.5. The SFDs sustain minimal damage under DBE‐level excitation. Under MCE‐level excitation, the SFDs in the D75V MRF continue to exhibit minimal damage, whereas the SMA cables in the D50V MRF develop residual deformation under some of the stronger ground motions due to the larger inter‐story drift and damper deformation demands.