Behaviour of T-shaped stiffened concrete-filled steel tubular stub columns after uniform and non-uniform fire exposure

The post-fire behaviour of T-shaped stiffened concrete-filled steel tubular stub columns was investigated by the heating and residual mechanical performance tests. Key parameters, such as heating duration, number of surfaces exposed to fire and the influence of the stiffening steel bars, were studied. Temperature distribution, failure modes, mid-height strain curves, and load-displacement curves were obtained and discussed. The study reveals that the number of fire-exposure surfaces significantly affects the temperature distribution of the specimen section. Both the bearing capacity and compressive stiffness decrease with the increase of fire exposure surfaces and heating time, whereas the ductility follows an inverse pattern. The transverse stiffeners can enhance the mechanical performance of these stub columns, especially for ductility.