Seismic Performance of Self-Centering Rotational Viscoelastic Dampers with Shape Memory Alloy Strands Under Mainshock-Aftershock Sequences

A self-centering rotational viscoelastic damper incorporating shape memory alloy strands is proposed for reinforced concrete coupling beams. Analytical formulations, finite element simulations, and nonlinear analyses of an 18-story building under 20 recorded mainshock-aftershock sequences assess its performance. The damper increases mean mainshock peak inter-story drift by 21% but reduces aftershock peak drift by 2%–36%. It also lowers base shear and floor acceleration, contributes to energy dissipation, and maintains small residual drifts, despite local increases at some stories. These results demonstrate potential benefits alongside a transient drift trade-off. Integrated-device experiments and fatigue validation remain necessary.