This　paper　reports　the　investigation　on　the　behavior　of　stub　columns　having　two　nested　steel　tubes　filled　with　concrete,　abbreviated　as　CFDST,　consisting　of　core　concrete,　inner　and　outer　steel　section　and　sandwich　concrete.　A　total　of　twenty-seven　stub　columns　were　fabricated　and　tested.　The　experimental　parameters　included　the　wall　thickness　of　the　outer　steel　tube,　strength　grade　of　the　concrete,　ratio　of　the　partial　compressive　area　and　the　cross-sectional　shape　of　the　bearing　plate.　The　typical　failure　modes,　load-displacement　relationships,　and　stressstrain　relationships　were　studied.　The　results　showed　that　outward　bulging　of　the　upper　end　of　the　outer　steel　tube　occurred　for　the　CFDST　columns,　and　the　degree　and　extent　of　bulging　increased　with　the　ratio　of　the　partial　compressive　area.　The　bearing　capacity　of　the　columns　loaded　on　the　partial　compressive　area　increased　with　the　wall　thickness　of　the　outer　steel　tube　and　concrete　strength.　When　the　wall　thickness　of　the　outer　steel　tube　increased,　the　partial　bearing　capacity　increased　by　25.3%　on　average.　Reduction　of　the　ratio　of　the　partial　compressive　area　improved　the　compressive　bearing　capacity.　However,　the　shape　of　the　bearing　plate　had　a　minor　effect　of　the　bearing　capacity.　Based　on　the　experimental　results,　the　FEM　model　was　developed　for　analyzing　the　bearing　capacity　of　the　CFST　and　CFDST　columns.　The　results　of　the　analyses　were　found　consistent　with　the　experimental　results.