Lateral　confinement　and　high　temperature　affect　the　load-carrying　capacity　of　a　concrete　member　significantly.　In　a　fire　condition,　a　concrete　member　exhibits　not　only　mechanical　deformation　but　also　thermal　deformation.　Therefore,　accurately　modeling　the　fire　behavior　of　confined　structural　concrete　is　challenging.　In　this　paper,　a　new　three-dimensional　thermo-plasticity　model　for　concrete　is　developed,　taking　both　high　temperature　and　confinement　into　account.　A　temperature-dependent　yield　surface　and　a　non-associate　flow　rule　are　formulated.　The　hardening　rules　for　concrete　are　proposed　as　a　function　of　confinement　and　temperature.　The　load-induced　strain　of　concrete　at　elevated　temperatures　is　calculated　by　using　a　stress-triaxiality　factor　to　consider　the　confinement　effect.　The　proposed　concrete　model　is　implemented　in　the　user-subroutine　(UMAT)　of　Abaqus,　in　which　Runge-Kutta-England　scheme　with　sub-stepping　is　used　to　update　stress　increment.　The　accuracy　of　the　proposed　model　is　validated　by　experiments　on　concrete　specimens,　circular　concrete-filled　steel　tubular　(CFST)　columns,　double-skin　CFST　(DCFST)　columns,　and　concrete-filled　double　steel　tubular　(CFDST)　columns.　It　is　shown　that　the　developed　thermo-plasticity　model　of　concrete　accurately　captures　the　behavior　of　confined　concrete　at　ambient　and　elevated　temperatures　and　can　be　incorporated　in　nonlinear　procedures　for　simulating　the　fire　resistance　of　composite　columns　exposed　to　fire.