This　paper　presents　experimental　investigations　into　the　behavior　of　axially　loaded　stub　columns　made　of　structural　steel　reinforced　concrete-filled　circular　steel　tubes　(SSR-CFCST)　after　exposure　to　elevated　temperatures.　A　total　of　135　SSR-CFCST　stub　columns　were　subjected　to　testing,　comprising　108　specimens　exposed　to　elevated　temperatures　and　27　reference　specimens　maintained　at　ambient　temperature.　The　parameters　considered　in　this　study　encompassed　steel　tube　thickness,　structural　steel　ratio,　concrete　compressive　strength,　and　temperature.　The　results　indicate　that　elevated　temperatures　and　steel　tube　thickness　exerted　significant　influences　on　the　residual　ultimate　load-bearing　capacity　of　the　specimens.　Specifically,　after　exposure　to　temperatures　of　900　°C,　the　columns　exhibited　a　serious　deterioration　in　their　residual　ultimate　load-bearing　capacity.　It　was　observed　that　increasing　the　steel　tube　thickness　notably　enhanced　the　fire　resistance　capacity　of　the　specimens.　Furthermore,　the　residual　ultimate　load-bearing　capacity　of　the　specimen　experienced　more　severe　degradation　with　higher　concrete　compressive　strength.　The　inclusion　of　embedded　structural　steel　contributed　to　the　stability　of　the　residual　ultimate　load-bearing　capacity　of　the　specimens.　In　terms　of　ductility,　there　was　a　substantial　increase　in　specimen　ductility　with　higher　structural　steel　ratio　and　steel　tube　thickness,　while　it　decreased　significantly　with　increasing　concrete　compressive　strength.　Notably,　after　exposure　to　temperatures　of　400　°C　and　600　°C,　specimen　ductility　improved.　The　initial　stiffness　and　ultimate　load-bearing　capacity　of　the　specimens　benefited　from　an　increase　in　the　structural　steel　ratio　and　concrete　compressive　strength.　Conversely,　the　initial　stiffness　decreased　with　the　rising　temperature　from　400　°C　to　900　°C.　Formulas　were　proposed　to　estimate　the　ultimate　load-bearing　capacity　of　the　specimens　under　ambient　temperature　conditions　and　after　exposure　to　elevated　temperatures,　respectively.　©　2024