Effects of Pulse Period and Frequency Content of Ground Motion Records on Fragility Curves of Mega-Configured Buckling-Restrained Braced Frames

This study estimates fragility curves for buckling-restrained braced frames (BRBFs) subjected to pulse-like excitations at the collapse prevention (CP), life safety (LS), and immediate occupancy (IO) performance levels. Four steel mega-configured BRBFs (4-, 8-, 12-, and 15-storey) are modeled using a finite element approach, and fragility analyses are conducted based on ground motion classifications by pulse period ([Formula: see text]) and the peak ground acceleration to peak ground velocity (PGA/PGV) ratio, an indicator of frequency content. Results show that in high-rise BRBFs, collapse probability differences between [Formula: see text] s and [Formula: see text] s ground motion records reach at least 45% at the maximum considered earthquake (MCE) level and 25% at the design basis earthquake (DBE) level with larger [Formula: see text] records causing more severe damage. Also, analyses indicated that as the PGA/PGV ratio increases in [Formula: see text] s records, the collapse probabilities of shorter BRBFs decrease, with the highest collapse probabilities associated with records where PGA/PGV [Formula: see text] [Formula: see text]g s/cm.