Experimental investigations on the seismic resilience upgrade of a damaged reinforced concrete frame retrofitted with self-centering damping braces

Post-earthquake investigations have highlighted the urgent need to retrofit damaged reinforced concrete (RC) frames. Traditional retrofitting methods usually aim to restore structural strength and stiffness without explicitly accounting for residual deformation control, making them difficult to repair after subsequent earthquakes. Hence, traditional retrofitting methods may struggle to maintain the post-event functionality of repaired structures, implying a requirement for new seismic resilience upgrade schemes. Owing to the excellent deformation recovery capacity, self-centering damping braces (SCDBs) may offer a promising solution. Yet, the retrofitting performance and connection mechanisms under initially damaged conditions remain unclear. This study experimentally investigates the feasibility of retrofitting damaged RC frames using SCDBs. Self-compacting concrete (SCC) was used to replace and repair the damaged concrete, and post-tensioned bolted connections were adopted to connect the braces to the RC frame. Prior to the structural test, the SCDBs and SCC were tested to quantify their mechanical properties. Then, a 2/3-scale damaged RC frame was selected for subsequent cyclic loading tests. The results showed that the retrofitted frame met the predefined objectives, including the enhanced strength, stiffness, energy dissipation capacity, and recentering capability.