Abstract: As a kind of high-performance metal damper, buckling-restrained braces (BRBs) dissipate seismic energy while the inner core also suffers fatigue damage induced by significant plastic deformations, which leads to the risk of brace fracture under strong earthquakes. This study mainly investigates the effects of BRB fracture behavior on the structural seismic performance. The BRB fatigue failure mechanism is revealed and the damage quantification approach is proposed. The results of the pushover analysis and non-linear time history analysis of four BRB-frame models show that the structural load-carrying capacity, stiffness, and energy-dissipating capacity are substantially reduced after BRBs fracture, while the inter-story drift ratio and residual deformations are significantly increased. The incremental dynamic analysis method is employed to conduct the seismic fragility analysis of structures. The results show that the structural collapse probability and post-earthquake repairability will be overestimated without considering the BRB fatigue failure behavior. It is suggested that BRB fracture behavior should be taken into account in the structural seismic analysis to quantify the seismic performance of structures more accurately.