Enhancing the Seismic Resilience of Reinforced Concrete Moment-Resisting Frame Structures Using a Combination of Buckling-Restrained Braces (BRBs) an‎d Steel Frames (SFs)

10/4/2026 12:00:00 AM

Residential buildings, as a major component of urban infrastructure an‎d the primary living environment for a large portion of the population, must possess adequate seismic resilience. In this study, four existing residential buildings with 4, 8, 12 an‎d 16 stories, located in Tehran an‎d constructed in the early 2000s with reinforced concrete moment-resisting frames in both directions, were eva‎luated, as they were identified to be in need of seismic retrofitting. To enhance their seismic performance, a retrofitting strategy proposed in a referenced study consisting of buckling-restrained braces (BRBs) combined with steel frames was implemented, an‎d their seismic resilience indices were assessed before an‎d after retrofit using the FEMA P-58 methodology. Within this framework, seismic risk analysis was employed to derive probabilistic distributions of repair cost an‎d repair time for various structural an‎d non-structural components under near-field an‎d far-field ground motions, considering two seismic hazard levels with 10% an‎d 2% probability of exceedance in 50 years. These results were then utilized to quantify the initial performance loss an‎d the recovery trajectory after earthquakes. By adopting a probabilistic approach, this thesis aims to provide a more reliable estimation of both initial economic losses an‎d post-earthquake recovery processes, enabling a more accurate eva‎luation of seismic resilience. The findings reveal that, across all hazard levels, the increase in structural stiffness due to retrofitting reduces damage to displacement-sensitive components while increasing damage to acceleration-sensitive components. However, since displacement-sensitive components are predominant in the studied cases, the overall repair cost an‎d repair time decrease after retrofit, resulting in an improvement in the seismic resilience index. Moreover, the case application of the methodology highlighted that the fragility functions embedded in the employed performance assessment software are not fully compatible with the structural an‎d non-structural components commonly used in Iranian buildings, indicating that their adaptation for the Iranian building stock requires substantial development an‎d updating.

متدولوژي 58-FEMA P , مهاربند كمانش‌تاب , تاب‌آوري لرزه‌اي , تحليل خطر لرزه‌اي احتمالاتي , منحني هاي شكنندگي

FEMA P-58 Methodology , Buckling-Restrained Brace (BRB) , Seismic Resilience , Probabilistic Seismic Hazard Analysis (PSHA) , Fragility Curves

Pouria Biglari

Dr. Vahid Broujerdian