Six　full-scale　square　concrete　filled　steel　tubular　(CFST)　stub　columns　with　the　cross-sectional　width　of　800　mm　were　tested　under　constant　axial　loading　and　cyclic　lateral　loading.　With　the　width-to-thickness　ratios　B/t　of　50,　80　and　100,　the　influence　of　the　confinement　effect　provided　by　the　steel　tube　to　core　concrete　on　the　failure　mode,　hysteretic　behavior,　ductility,　stiffness,　and　energy　dissipation　of　the　CFST　columns　was　investigated.　It　is　found　that:　(D　the　failure　mode　of　all　specimens　is　the　compression-flexural　failure　with　the　local　buckling　of　steel　tube　and　the　crushing　of　core　concrete　at　the　bottom　of　the　columns;　(2)　with　the　decrease　of　the　width-to-thickness　ratio　(the　confinement　effect　improved)　the　influence　of　the　ductility　of　columns　is　not　significant,　and　in　comparison　with　the　scale　columns,　the　ductility　performance　of　the　full-scale　columns　decreases　obviously;　(3)　the　effect　of　the　width-to-thickness　ratio　on　the　stiffness　degradation　and　energy　dissipation　of　the　full-scale　columns　is　not　significant,　and　with　the　decrease　of　width-to-thickness　ratio,　the　cumulative　energy　of　the　specimens　increases;　(4)　as　the　width-to-thickness　ratio　decreases　with　the　increase　of　the　confinement　effect,　the　compression　and　flexural　capacity　increases,　but　the　increased　extent　of　the　compression　and　flexural　capacity　is　smaller　than　that　in　the　current　codes.　In　addition,　according　to　the　current　design　codes　of　China　and　Europe,　the　predicted　values　are　larger　than　that　of　the　experimental　values　of　the　full-scale　CFST　columns.　The　calculated　formulas　in　the　code　of　America　are　rather　conservative.　©　2023　Chinese　Vibration　Engineering　Society.　All　rights　reserved.