Gusset plate friction damper with double plate core buckling-restrained brace

Buckling-restrained braces (BRBs) are widely applied in building structures to control vibrations during major earthquakes. However, conventional BRBs do not yield or dissipate energy at low vibration amplitudes. To address this concern, this study proposes gusset plate friction dampers (GPFDs) with a double-plate core buckling-restrained brace (BRB). To delay the BRB action, gusset plates with multiple slot holes were used. Under a small vibration, a friction force is generated at the brace-end connection portions, whereas under a large vibration, the bolts contact the gusset plates, and the core plates of the BRB yield with a delay. Therefore, a BRB with GPFDs can provide a double-stage energy-dissipation mechanism for various earthquake intensities. Cyclic loading tests were performed for the test specimens of the BRB with GPFDs, and the results revealed a superior hysteretic performance, exhibiting double-stage energy dissipation. Furthermore, loading tests and finite element analyses were performed for connections with misaligned slot holes in the gusset plate to investigate the manufacturing accuracy requirements of slot holes for a safer design.