James Michael Ricles

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.

The social and economic losses caused by an earthquake can be mitigated by using a rolling pendulum (RP) isolation system to protect vital non‐structural building contents. In this paper, a physics‐based mathematical model for an RP bearing—as well as an isolation systems comprised of these bearings—is derived. An experimental campaign for multi‐directional characterization of RP isolators was conducted. A single, full‐scale (four RP bearings) isolation system was tested. These tests were performed using an in‐plane multi‐directional shake table. Restoring forces and moments were measured by restraining the top of the isolation system from moving horizontally by using three struts with uniaxial load cells. Controlled‐displacement characterization tests were defined to capture the envelope performance of the isolation system subjected to a variety of multi‐directional conditions, by specifying combinations of slow and fast tests, various in‐plane (, , and ) amplitudes and frequencies, and different orbits. The experimental results were used to calibrate and validate the mathematical model.