For　increasing　the　seismic　capabilities　of　existing　concrete　frames,　a　steel　frame　with　buckling-restrained　braces　(BRBs)　is　externally　added　without　significant　increment　of　inner　forces　within　the　existing　frame.　One　pure　concrete　frame　model　and　two　concrete　frame　models　retrofitted　with　externally　added　BRB　steel　frames　were　designed　and　manufactured,　and　statically　cyclic　loading　tests　were　conducted.　Seismic　performance　of　the　structures,　including　the　status　of　cracks　and　failures,　the　hysteretic　shear　force-lateral　displacement　curves,　the　skeleton　curves,　the　degradation　of　equivalent　stiffness,　the　equivalent　damping　ratio,　and　the　relation　between　strain　and　shear　force　in　the　external　steel　frames　and　the　concrete　beams,　has　been　investigated　through　the　tests.　It　is　indicated　that　with　the　externally　added　steel　frames,　the　hysteretic　shear　force-displacement　curves　have　full　shapes　while　the　failure　mechanism　is　improved　reasonably,　and　BRBs　can　dissipate　seismic　energy　stably.　Shear　bearing　capacity　of　the　retrofitted　structures　can　increase　by　at　least　two　times　than　that　of　the　existing　concrete　frame.　The　existing　structure,　the　added　steel　frames　and　the　installed　BRBs　coordinate　well.　Within　the　seismic　design　target,　the　brittle　compression-shear　failure　of　concrete　columns　can　thus　be　avoided.　Finally,　the　design　suggestions　for　improving　the　connection　details　of　the　externally　added　steel　frames　has　been　put　forward.　©　2017,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.