Abstract
This study presents a comprehensive seismic fragility assessment of non-ductile reinforced concrete (RC) frame buildings retrofitted with buckling-restrained braces (BRBs). Many existing RC structures, particularly those designed prior to modern seismic codes, exhibit significant deficiencies in ductility and strength, making them highly vulnerable to earthquake damage. BRBs offer an effective retrofitting solution by providing stable hysteretic damping and preventing buckling under compression. The research employs nonlinear dynamic analysis, specifically Incremental Dynamic Analysis (IDA), on representative multi-story non-ductile RC frame models, both in their original and BRB-retrofitted configurations. A suite of ground motions scaled to increasing intensity levels was used to generate the IDA curves. Fragility curves were subsequently developed for various performance levels, including immediate occupancy, life safety, and collapse prevention, based on defined inter-story drift ratios. The results demonstrate a substantial enhancement in seismic performance for the BRB-retrofitted frames, characterized by a significant shift in the median collapse intensity and a reduction in the dispersion of the fragility curves. This quantitative assessment highlights the efficacy of BRBs in improving the seismic resilience and reducing the vulnerability of non-ductile RC structures, providing valuable insights for performance-based seismic design and retrofitting strategies.
