Comparison of resilience index of a steel frame retrofitted with steel brace system and a reinforced concrete shear wall, based on FEMA P-58 performance-based assessment (A school case study)

Over recent decades, devastating earthquakes have frequently struck Iran, causing substantial damage upon its existing infrastructure. These seismic events have tragically resulted in extensive human casualties and severe economic losses, thereby underscoring the critical importance of assessing the impact of single or multiple seismic occurrences on various building types. This imperative has consequently garnered significant attention from the research community. The occurrence of a seismic event inherently carries the potential for widespread damage to infrastructure, particularly to existing buildings, which can subsequently lead to injuries and fatalities. It is therefore incumbent upon structural and earthquake engineers to minimize the extent of such damage, injuries, and human fatalities. Therefore, the assessment of the seismic resilience of critical structures assumes a pivotal role in comprehensive disaster prevention and mitigation strategies. Among societal cohorts, students and educational staff represent some of the most vulnerable populations susceptible to both natural and human-caused disasters. Ensuring the continuity and safety of their educational processes thus requires rigorous attention to the resilience of their educational environments. For the current case study, a school building situated in Tehran, with a total floor area of 1390 square meters, was selected as the representative sample. The objective was to thoroughly assess its seismic resilience, serving as a sample for educational facilities across the city. Initially, the structural performance was evaluated through nonlinear static analysis. Upon the identification of structural inadequacies, a comprehensive seismic retrofitting initiative was undertaken. After a thorough review of various structural strengthening methodologies, two distinct methods were ultimately adopted for the seismic upgrade of this school: Special Concentric Braced Frames (SCBF) and Reinforced Concrete (RC) Shear Walls. After retrofitting with these two methods, IDA, fragility, and vulnerability curves were drawn based on the results from both scenarios. Also, an estimate of implementation costs was made using PACT software. In this study, to verify the effectiveness and performance level of the retrofitting methods, the FEMA P-58 methodology was employed across various seismic risk levels (2%, 10%, 20%, and 50% in 50 years). The results of this process demonstrate a significant reduction in financial losses and recovery time for the structure retrofitted using the two mentioned scenarios. Furthermore, the overall resilience index has improved. However, retrofitting with reinforced concrete shear walls showed superiority compared to special concentric braced frames. Furthermore, a damage assessment was carried out in this research. This assessment utilized the FEMA P-58 methodology, with the PACT software serving as a key tool for its execution.