A modified rotational friction damper for seismic performance enhancement of steel structures considering soil-structure interaction

This study introduces and evaluates a novel Modified Rotational Friction Damper (MRFD) developed to overcome the limitations of conventional friction dampers in seismic protection. The MRFD incorporates three key innovations: (i) a Belleville washer-based clamping system that ensures stable and reliable preload, (ii) a bronze-filled PTFE-stainless steel friction interface providing a consistent coefficient of friction, and (iii) an SMA-assisted restoring mechanism that generates a flag-shaped hysteresis loop, enabling effective self-centering and minimizing residual drifts. To assess its performance, a fifteen-story steel moment-resisting frame was analyzed under seven far-field ground motions, considering both fixed-base and soil-structure interaction (SSI) conditions. Nonlinear time-history analyses demonstrate that the MRFD significantly reduces seismic demands: peak floor accelerations decreased by up to 36%, base shear by more than 30%, and inter-story drift by over 32%, while the device dissipated 40–55% of the input seismic energy. The combined MRFD-SSI configuration exhibited the most favorable overall performance. These results highlight the MRFD’s potential for integration into performance-based seismic design and retrofitting strategies, offering a cost-effective and reliable solution to enhance the resilience of steel structures in seismically active regions.