The　fibre　beam　element　(FBE)　method　has　been　widely　used　to　investigate　the　behaviors　of　concrete-filled　steel　tube　(CFT)　columns　for　its　high　efficiency　and　accuracy.　The　existing　models　were　generally　developed　or　calibrated　by　using　specimens　with　relatively　small　size,　in　which　the　size　effects　were　ignored　or　poorly　incorporated.　Additionally,　most　existing　FBE　models　focused　on　CFT　stub　columns.　In　this　paper,　a　new　FBE　model　for　nonlinear　analysis　of　concentrically　loaded　stub　and　slender　columns　was　proposed,　in　which　the　size　effects　on　the　effective　stress-strain　relationships　of　steel　tube　and　core　concrete　were　well　incorporated.　The　proposed　FBE　models　were　then　used　to　develop　an　ultimate　strength　model　for　the　design　of　both　stub　and　slender　columns.　A　total　of　1029　specimens　assembled　from　72　previous　studies　were　used　to　verify　the　proposed　models.　The　results　suggested　that　the　proposed　FBE　model　performs　quite　well　for　both　small-　and　large-　size　CFT　stub　columns　and　predicts　the　behaviors　of　slender　columns　with　reasonable　accuracy.　Moreover,　the　ultimate　strength　model　developed　based　on　the　proposed　FBE　models　was　found　to　make　satisfying　prediction　of　test　results.