Comparison of seismic resilience of steel frame structure equipped with double-stage and conventional buckling-restrained braces

An asynchronized parallel double-stage buckling restrained brace (APDBRB) is proposed to overcome the limitations of buckling restrained brace (BRB), emphasizing the concurrent control of seismic responses and resilience of steel frames (SFs) under both the design basis earthquake (DBE) and maximum considered earthquake (MCE). To identify these advantages, one SF, one SF equipped with BRB (SFBRB), and 15 SFs equipped with APDBRB (SFAPDBRBs) were analyzed. Significant improvements in structural seismic performance and resilience were observed using APDBRB. (1) APDBRB reduced the repair time of SF from 45.39 to a minimum of 8.5 d under DBE and from 90.95 to a minimum of 25.4 d under MCE, while those of SFBRB reached 17.88 and 52.76 d under DBE and MCE, mostly due to the effective control of absolute floor acceleration (MAFA) under DBE and maximum inter-story drift ratio (MIDR) under MCE.(2) APDBRB reduced the restoration cost of SF by up to 81.20 % under DBE and 58.93 % under MCE, which were significantly better than those of BRB (50.74 % under DBE and 47.31 % under MCE), realized by the concurrent control of MIDR and MAFA. (3) BRB improved the resilience level of SF from 0 to 1, whereas the resilience levels of the well-designed SFAPDBRBs reached Level 2.