Quasi-static　tests　were　conducted　to　investigate　the　effects　of　buckling　restrained　braces　(BRB)　on　the　seismic　performance　of　resilient　recycled　aggregate　concrete　(RAC)　composite　frames　with　ultra-high　strength　steel　bars　(UHSB).　The　damage　processes,　hysteretic　characteristics,　stiffness　and　strength　degradation,　energy　dissipation　capacity,　strain　development　of　steel,　residual　drifts　and　residual　crack　widths　of　specimens　were　analyzed.　Overall,　the　effects　of　BRB　on　the　crack　propagation　of　specimens　were　minor,　both　of　which　exhibited　a　beam　hinge　failure　mechanism.　After　setting　BRB,　the　damage　to　RAC　was　reduced　within　the　range　of　gusset　plates,　and　the　spalling　area　of　RAC　in　columns　was　significantly　diminished.　When　the　horizontal　drift　reached　1.5　%,　the　stiffness,　bearing　capacity　and　energy　dissipation　capacity　were　increased　by　102　%,　66　%　and　186　%,　respectively.　Moreover,　the　residual　drift　was　slightly　larger,　but　the　residual　crack　width　remained　invariable.　Considering　the　weak　bonding　property　of　UHSB　and　fractures　of　BRB,　finite　element　models　of　specimens　were　established.　The　simulated　results　indicated　that　as　the　stiffness　ratios　and　BRB　area　ratios　increased,　the　peak　bearing　capacity　of　specimens　improved.　It　was　recommended　that　the　stiffness　ratios　and　BRB　area　ratios　should　be　within　the　range　of　0.50–2.00　and　0.50–1.00,　respectively.　©　2025　Elsevier　Ltd