Probabilistic assessment of the seismic performance of tall reinforced concrete buildings under repeated earthquakes using the Endurance Time Method

The occurrence of repeated earthquakes in Turkey in 2023 and the widespread destruction they caused have heightened the necessity of assessing the seismic performance of structures. With the growth of tall buildings in earthquake-prone areas, examining their behavior under repeated earthquakes is essential. This study investigates the probabilistic seismic performance of a 35-story reinforced concrete building with a special moment-resisting frame and shear wall system as a benchmark model in a highly seismic region. The structure is designed according to the fourth edition of Iran’s Standard 2800 using ETABS software and then analyzed in PERFORM-3D for nonlinear evaluations. The analyses include nonlinear dynamic time history analysis using the endurance time method under repeated earthquakes, utilizing records from the far field as per FEMA-P695 guidelines. The objective is to extract and compare fragility curves for single and repeated earthquakes. Results indicate that the structure’s behavior under repeated earthquakes, particularly at medium and high damage levels, significantly differs from that under a single earthquake. For instance, the median fragility increase at medium damage levels after the second earthquake is reported as 24% and 38% in the x direction for the design-level and maximum considered earthquakes, respectively, and 27% and 37% in the y direction. Additionally, the median fragility increase at high damage levels is reported as 28% and 42% in the x direction and 30% and 42% in the y direction. These findings underscore the importance of considering recurring earthquakes in the design of tall buildings