PSI - Issue 78

Parvane Rezaei Ranjbar et al. / Procedia Structural Integrity 78 (2026) 615–622

622

5. Conclusions This study presented a comprehensive seismic fragility assessment of a pre-code reinforced concrete school building retrofitted using a dual-frame, self-centering rocking exoskeleton system. By applying Incremental Dynamic Analysis (IDA), the research provided detailed fragility curves that capture the probabilistic performance of the structure under varying seismic intensities, and showed that the retrofit significantly improved the building’s seismic resilience. The enhanced spectral acceleration thresholds observed across all damage states confirm the effectiveness of the rocking system in boosting structural capacity, reducing residual drift, and ensuring self-centering performance. This leads to a substantial reduction in the likelihood of extensive or complete damage, particularly at intensity levels corresponding to the Life Safety limit state. The findings underscore the importance of three-dimensional modeling and the application of bi-directional ground motions for accurate fragility curve calibration. The observed directional differences in structural vulnerability - especially the greater fragility in the Y-direction - highlight the necessity of directional sensitivity in seismic design and retrofit strategies. The findings highlight the potential of dissipative exoskeletons as a strategic and scalable solution for upgrading vulnerable building stock in seismic-prone regions. References Cornell, C.A., Jalayer, F., Hamburger, R.O. & Foutch, D.A., 2002. Probabilistic basis for 2000 SAC FEMA steel moment frame guidelines. J Struct Eng 128, 526 – 533. Eurocode 8, 2004. Design of structures for earthquake resistance. European Committee for Standardization, Brussels. Federal Emergency Management Agency, 1999. HAZUS Earthquake Loss Estimation Methodology. Technical Manual. 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