A finite element (FE) investigation into the compressive behaviour of concrete-filled double skin tubular (CFDST) cross-sections with lean duplex andferritic stainless steel outer tubesis presented. FE models were initially developed and validated against available test results reported in the literature. Upon successful replication of the ultimatecapacities, load–deformation histories and failure modes exhibited by the tested CFDSTstub columns,a parametric studywas undertaken to investigate the influence of keyvariables, including the local slendernessesof the outer and inner tubes, the concrete strengthand the adopted grade of stainless steel, on the ultimate response of the studied CFDST stub columns. Based on the generated FE data pooland theavailable test results, the applicability of the existing European, Australian and American design provisions for composite carbon steel members to the design of the studied CFDST cross-sectionswas evaluated. All the examined design rules are shown to yield unduly conservative (less so for the higher concrete grades) and rather scattered capacity predictions. Modifications to the design treatment in relation to the effective area of the outer tubes,to take due account of outward-only local buckling,and the effective compressive strength of the infilled concrete,to reflect the reduced relative effectiveness of higher concrete grades,are considered. The modified design rules are shown toimprove the accuracy and consistencyof the design capacity predictions. Finally, statistical analyses were carried out to demonstrate the reliability of the modified design approaches.