In　this　study,　seven　pinned　double-rectangular　tube　assembled　buckling-restrained　brace　(DRT-ABRB)　specimens　were　experimentally　characterised　by　means　of　an　axial　cyclic　test.　The　core　member　of　the　specimens　was　a　single　flat-plate.　Two　rectangular　tubes　were　assembled　using　high　strength　bolts　to　form　an　external　restraining　member.　Each　rectangular　tube　was　composed　of　an　external　steel　channel　and　a　cover　plate.　A　gap　or　thin　rubber　filler　was　set　between　the　core　and　the　external　restraining　member　to　form　an　unbonded　layer.　The　influence　of　several　design　parameters　on　the　failure　mode　and　energy　dissipation　capacity　of　the　ABRB　was　investigated,　including　the　height　of　the　core　wing　plate,　thickness　of　the　external　cover　plate,　and　height　of　the　external　channel　flange.　This　experimental　study　demonstrated　that　a　local　pressure-bearing　failure　at　the　end　of　the　external　member　arises　when　the　external　cover　plate　is　too　thin　or　if　the　end　construction　detail　is　unreasonable.　When　the　end　rotations　of　the　DRT-ABRB　were　restricted,　the　hysteretic　performance　was　shown　to　be　superior　to　that　of　a　pure　pinned　DRT-ABRB.　Finally,　all　the　tested　DRT-ABRBs　exhibited　excellent　energy　dissipation　performance　which　amply　satisfied　existing　regulation　requirements.