Seismic Performance of Steel Frame Structures with Novel Self-Centering Beams: Shaking-Table Tests and Numerical Analysis

Conventional buildings often face major repair challenges after earthquakes. Self-centering technology is an innovative approach that enables structures to resist seismic events with minimal residual drift by incorporating automatic recovery mechanisms, allowing the structure to return to its original position after an earthquake, thus enhancing seismic resilience and reducing the need for extensive repairs. This study presents an innovative self-centering beam technology aimed at enhancing earthquake resilience and limiting floor elongation during seismic events. Through an experimental investigation involving a 3-story steel frame, the research compares the performance of conventional frames (CFs) with that of self-centering frames (SCFs) equipped with self-centering devices at various beam-column connections. The comparative analysis reveals that SCF structures exhibit a consistent reduction in interstory drift ratios from the bottom to the top stories, in contrast to the fluctuating drift ratios observed in CF structures across different stories. Models with and without initial preload forces in the beams were also evaluated. Notably, the SCF-A model, which incorporates preload, significantly outperformed CFs in reducing drift ratios during major earthquakes. Conversely, the SCF-B model, devoid of preload, showed similar or increased drift ratios compared to SCF-A under moderate and major seismic events. The SCF structures, particularly those with reduced initial preload, displayed lower acceleration amplification and a modified acceleration distribution pattern. Their hysteretic behavior also contrasted with that of CF structures, with SCF-A demonstrating smaller yielding moments and SCF-B presenting fuller hysteresis curves when compared to SCF-A, yet less pronounced than those of CFs. In terms of base moments, SCF-A and SCF-B structures achieved reductions of 38.0% and 55.1%, respectively, under major earthquakes compared to their CF counterparts. The study concludes that preload force, damping devices, and column base types are crucial in self-centering structures' design, influencing displacement, self-centering ability, and energy dissipation. This provides insights for future applications of SCF structures with the novel self-centering beams.