Seismic Retrofit of RC Buildings Using Self-centering Friction-Damped Steel Exoskeletons Based on P-Spectra Design Methodology

Existing Reinforced Concrete (RC) buildings designed according to older seismic codes often exhibit inadequate lateral strength and poor deformation capacity, making them particularly vulnerable during strong earthquakes. Modern retrofitting strategies aim not only to limit structural damage by including dissipative components but also to control residual drifts, a key indicator for post-earthquake reparability and rapid functionality recovery. This study investigates the seismic retrofit of an existing RC frame structure through an exoskeleton, equipped with self-centering friction-damped devices. A three-story benchmark RC school building is adopted as a case study and retrofitted with the proposed technology. Performance-Spectra (P-Spectra) approaches are used to design the retrofit intervention, while establishing a direct relationship between target mechanical properties of self-centering exoskeletons, and ensuring a performance-driven design process. Non-linear time history analyses are performed by considering the adopted case study with and without the exoskeleton retrofit intervention and used to assess their seismic response under a compatible set of ground motion. The results highlighted the effectiveness of self-centering exoskeletons and the proposed design methodology in delivering resilient seismic performance while reducing functional disruption.