Seismic response control of recentering steel frame with innovative SMA-high damping rubber dampers under sequential earthquakes

In this study, a novel self-centering high-damping rubber damper (SMA-HRD), incorporating shape memory alloy (SMA) filament ropes, was developed. Both the conventional high-damping rubber damper (HRD) and the SMA components were designed and tested, with an assessment of their mechanical properties across various loading frequencies. A finite element model of a self-centering functional steel frame equipped with this damper was established to perform seismic time-course analysis under the main aftershock sequence. The results indicated that the hysteresis curve of the HRD becomes fuller as the loading frequency increases. Similarly, the hysteresis curve of the SMA-HRD also becomes fuller with increasing loading frequency, and the resetting effect is pronounced due to the inclusion of the SMA filament rope. Displacement time-history analysis of the main aftershock sequence showed that an ordinary steel frame still had unrecoverable deformation 20 s after the mainshock, creating unfavorable initial conditions for the subsequent aftershock and exacerbating further damage to the structure. Under rare earthquake conditions, the peak and residual interstory drift of ordinary steel frames surpassed the limits set by seismic codes. The maximum interstory drift angle of self-centering nodal frames also surpassed these thresholds. However, frames equipped with SMA-HRD and SMA-HRD composite self-centering nodal frames demonstrated superior seismic performance. Notably, the SMA-HRD significantly reduced the peak interstory displacement in the self-centering nodal frames, demonstrating its potential to enhance seismic resilience.