T-shaped　reinforced　concrete　(T-RC)　beams　are　widely　used　in　high-rise　buildings　due　to　their　advantages　of　reduced　concrete　usage,　low　sectional　stress,　and　decreased　weight　of　the　structure.　However,　the　calculation　method　of　residual　flexural　stiffness　of　T-RC　beams　has　limited　existing　research.　To　address　this　knowledge　gap,　a　comprehensive　experimental　investigation　was　conducted,　comprising　fire　tests,　dynamic　tests,　and　static　load　tests　on　10　T-RC　beams.　The　aim　was　to　analyze　the　effects　of　fire　time　and　load　ratio　on　the　residual　flexural　stiffness　of　composite　beams.　The　experimental　results　showed　that　the　residual　flexural　stiffness　of　T-RC　beams　decreased　with　increasing　fire　time　and　load　ratio.　However,　the　impact　of　fire　time　was　more　significant　than　the　load　ratio.　A　refined　finite　element　model　of　T-RC　beams　under　high　temperature　and　after　high　temperature　was　established　by　modifying　the　frequency　data　of　the　dynamic　test　and　considering　the　impact　of　cracks.　The　model　accurately　predicted　the　temperature　field　and　deflection　change　of　T-RC　beams　under　fire.　Furthermore,　a　method　for　calculating　the　residual　flexural　stiffness　of　T-RC　beams　considering　the　effect　of　fire　was　proposed　and　validated　against　the　measured　values.　The　proposed　method　demonstrated　a　low　error　rate　of　less　than　10%.　　©　2023　American　Society　of　Civil　Engineers.