This　paper　proposes　a　new　type　of　buckling-restrained　braces　(BRBs),　namely　shuttle-shaped　buckling　restrained　braces　(SS-BRBs).　The　proposed　SS-BRB　is　composed　of　a　circular　steel　tube　as　the　inner　core,　and　a　shuttle-shaped　thin-walled　steel　tube　as　the　external　restraining　member.　The　space　between　them　is　filled　by　a　steel-plate　isolation　system.　The　shuttle-shaped　restraining　member　of　the　SS-BRB　significantly　improves　load-carrying　efficiency　and　saves　material　in　its　strength　design.　Moreover,　the　SS-BRB　is　more　aesthetically　appealing　and　can　be　utilized　as　an　exposed　BRB　in　long-span　or　spatial　structures.　In　terms　of　the　concept　of　restraining　ratio　of　a　BRB,　no　design　method　of　an　SS-BRB　is　available　currently　because　it　concerns　the　solution　of　the　elastic　buckling　load　of　an　SS-BRB.　Therefore,　the　elastic　buckling　load　of　a　pin-ended　SS-BRB　is　initially　studied　by　adopting　the　equilibrium　method　and　is　further　verified　through　finite　element　(FE)　method.　The　lateral　displacement　function　of　an　SS-BRB,　and　the　longitudinal　stress　at　the　extreme　fiber　of　the　external　restraining　member　are　derived　by　considering　an　initial　geometric　imperfection　that　is　consistent　with　the　first　order　overall　buckling　shape　of　the　SS-BRB.　A　correction　factor　considering　shear　deformation　has　been　incorporated　for　a　more　accurate　prediction.　The　lower　limit　of　the　restraining　ratio　for　a　load-bearing　type　of　SS-BRBs　is　further　obtained　based　on　yielding　of　the　extreme　fiber　of　the　restraining　member.　Furthermore,　the　proposed　formula　has　incorporated　a　strain　hardening　factor　for　the　SS-BRB　that　experiences　strain　hardening　of　the　core　after　its　initial　yielding.　The　proposed　formulas　have　been　validated　through　FE　numerical　analysis.　The　findings　in　this　paper　provide　fundamentals　to　develop　the　design　method　for　an　energy-dissipation　type　of　SS-BRBs.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.