CONTROLLED ROCKING STEEL BRACED DUAL-FRAMES FOR SEISMIC RETROFIT OF RC BUILDING STRUCTURES

Recently, various seismic design approaches have introduced controlled rocking systems to mitigate damage concentration and achieve self-centering against varying ground motion intensities. Among these, the self-centering rocking steel-braced frame stands out as a high-performance system capable of preventing significant structural damage and reducing residual drifts in large earthquakes. This system comprises braced steel frames designed to remain elastic and rock off their foundation. It features overturning resistance from elastic post-tensioned steel cables, ensuring a reliable self-centering restoring force, along with replaceable structural fuses for energy dissipation. This study focuses on the design and evaluation of rocking steel coupled frames used as dissipative exoskeletons for seismic retrofitting of RC buildings, using a real case-study residential building. The design employs a displacement-based approach, with the structural fuses made of dumbbell-shaped steel strips selected to prevent stress concentration, plastic strain accumulation, and premature buckling failures. The retrofit strategy's effectiveness is validated through nonlinear time-history analyses with different earthquake ground motion scenarios.