Conventional　concrete-filled　aluminum　alloy　tube　(CFAT)　can　effectively　delay　the　inward　local　buckling　of　aluminum　alloy　tube　(AA).　This　paper　experimentally　and　numerically　investigates　the　suitability　of　strengthening　square　and　rectangular　hollow　section　(SHS　and　RHS)　CFAT　beams　with　a　layer　of　carbon-fiber　reinforcement　polymer　(CFRP)　under　four-point　bending.　Among　40　beams,　30　square　and　rectangular　CFAT　beams　were　strengthened　with　CFRP　comprising　three　arrangement　schemes　of　CFRP　and　10　conventional　square　and　rectangular　CFAT　beams　were　treated　as　reference　beams.　Flexural　stiffness　of　square　and　rectangular　CFAT　beams　are　remarkably　enhanced　by　external　bonded　CFRP,　while　the　ductility　is　decreased.　The　bottom　flange-bonded　CFRP　scheme　is　less　effective　in　enhancing　ultimate　strength　of　CFAT　beams　than　that　of　four　sides-bonded　CFRP　scheme.　New　design　approaches　for　evaluating　both　initial　and　post-yield　flexural　stiffness　of　square　and　rectangular　CFAT　beams　strengthened　with　CFRP　are　proposed.　FE　models　are　correctly　simulated　to　analyze　the　flexural　behavior　of　square　and　rectangular　CFAT　beams　strengthened　with　CFRP.　CFRP　strengthening　technique　using　in　this　study　can　remarkably　enhance　the　ultimate　strength　of　square　and　rectangular　CFAT　beams　and　effectively　delay　the　outward　local　buckling　of　AA　tubes.　©　2020　Elsevier　Ltd