This　paper　describes　experimental　and　numerical　investigations　into　the　structural　behavior　of　circular　concrete-filled　double　steel　tubular　(CCFDST)　slender　columns　loaded　concentrically　to　failure.　Test　results　on　8　specimens　including　6　CCFDST　slender　columns　and　2　CCFDST　short　columns　are　reported　in　this　study　that　demonstrate　the　influences　of　column　slenderness　ratio　and　the　thickness　of　the　internal　steel　tube　on　the　responses　of　CCFDST　columns.　A　numerical　model　based　on　fiber　analysis　is　developed　to　predict　the　axial　load–deflection　responses　of　CCFDST　slender　columns.　The　numerical　model　of　CCFDST　columns　accounts　for　the　effects　of　initial　imperfection,　concrete　confinement,　material　nonlinearities　and　the　interaction　between　axial　load　and　deformations.　A　parametric　study　is　performed　by　means　of　employing　the　verified　computational　technique　to　ascertain　the　sensitivity　of　the　performance　of　CCFDST　slender　columns　to　various　important　parameters.　Comparative　analyses　are　undertaken　to　evaluate　the　applicability　of　Eurocode　4　and　AISC　360–16　for　conventional　concrete-filled　steel　tubular　columns　(CFST)　to　CCFDST　slender　columns.　It　is　shown　that　the　developed　numerical　modeling　technique　simulates　well　the　structural　behavior　of　CCFDST　slender　columns　and　is　an　efficient　computer　simulation　tool　for　the　analysis　and　design　of　such　composite　columns.　Moreover,　the　current　design　codes　need　to　be　modified　to　be　utilized　for　designing　CCFDST　columns.　©　2022　Elsevier　Ltd