نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Background: Seismic resilience of reinforced concrete (RC) moment-resisting frames subjected to earthquake sequences, particularly those equipped with supplemental energy-dissipation systems, is an important aspect of performance-based seismic design. Despite the favorable energy absorption and dissipation capacity of buckling-restrained braces (BRBs), the combined effects of mainshock–aftershock sequences, building height, number of bays, and seismic hazard level on the resilience of BRB-retrofitted RC frames remain insufficiently investigated. This study aims to quantitatively evaluate these effects on the seismic resilience of BRB-retrofitted RC moment-resisting frames.
Methods: Three groups of two-dimensional RC frames with 5, 10, and 15 stories and three- and five-bay configurations were designed according to high-level seismic provisions for special ductility and modeled in OpenSees. Nonlinear dynamic time-history analyses were performed using recorded real earthquake sequences. Spectral acceleration at the fundamental period was selected as the intensity measure, and maximum interstory drift ratio was adopted as the engineering demand parameter. Structural damage was quantified according to four performance levels: Immediate Occupancy, Life Safety, Collapse Prevention, and Complete Collapse. Fragility curves were developed to estimate damage probabilities and assess resilience degradation under Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE) hazard levels.
Results: The results show that increasing building height and the number of bays significantly increases structural damage and reduces seismic resilience due to greater lateral flexibility, larger interstory drift demands, and concentration of residual deformations in lower and middle stories. The mainshock accounts for more than 80% of total damage, whereas the aftershock has a limited effect unless the structure remains in the nonlinear response range after the mainshock. Increasing the hazard level from DBE to MCE causes a substantial reduction in resilience, particularly in high-rise and five-bay frames.
Conclusion: Earthquake intensity, building height, and number of bays are the key factors governing the seismic resilience of BRB-equipped RC frames. Taller and five-bay frames exhibit greater vulnerability to resilience degradation because of their higher drift demands. The proposed fragility-based framework can support performance-based seismic design and post-earthquake assessment of RC buildings. Future studies should consider three-dimensional structures, alternative bracing configurations, and soil–structure interaction
کلیدواژهها English
