To　address　global　durability　and　sustainability　challenges　of　coastal　infrastructures,　this　paper　investigated　the　axial　compressive　behavior　of　concrete-encased　steel　(CES)　components　under　chloride-induced　corrosion.　Accelerated　corrosion　and　axial　loading　tests　were　conducted　on　twelve　CES　slender　columns.　Results　indicated　that　corrosion-induced　expansion　significantly　damaged　the　concrete　cover,　with　higher　slenderness　ratios　exacerbating　the　deterioration　of　axial　performance.　Increasing　the　slenderness　ratio　from　32　to　51　at　a　20　%　corrosion　rate　led　to　17.1　%　and　18.3　%　greater　reductions　in　axial　capacity　and　initial　stiffness,　respectively.　Traditional　methods,　considering　only　concrete　cracking　and　steel　corrosion,　underestimate　the　beneficial　confinement　effect　from　corrosion-induced　expansion.　Thus,　confining　stresses　due　to　corrosion　product　expansion　at　varying　corrosion　rates　were　theoretically　derived.　Incorporating　combined　confinement　from　corroded　steel　and　corrosion　products　significantly　improved　axial　stability　capacity　predictions,　validated　by　experimental　data.　A　new　finite　element　modeling　approach　incorporating　these　combined　confinement　effects　provided　results　closely　matching　tests,　reinforcing　the　necessity　of　this　modeling　improvement.　This　research　contributes　valuable　insights　into　accurately　assessing　coastal　infrastructure　performance　in　chloride　environments.　©　2025　Institution　of　Structural　Engineers