Investigation of intumescent coating on the fire endurance of concrete-filled steel columns with varied characteristics

Concrete-filled steel columns (CFSC) are becoming increasingly popular in contemporary construction, particularly for the construction of tall buildings and structures with large spans. These columns offer superior fire protection compared to concrete or steel-only columns. Furthermore, CFSCs offer significant structural benefits by enhancing properties such as high tensile and compressive strength, ductility, capacity for energy absorption, improved fire resistance, and thermal insulation. However, there remains a notable research gap pertaining to the comprehensive analysis of the temperature distribution in CFSC sections that are protected by intumescent fire coating (IFC). Particularly, there is a need to investigate the specific effects of various heating rates, intumescent coating thickness, and steel thickness on the temperature distribution within these sections. The current research involved the creation of a finite element model for analyzing heat transfer and fire resistance in columns. This model was used to examine how the columns would perform under different fire conditions, including Standard (ISO-834), Fast, Slow, and Smouldering fires. The model has been verified with the available literature. Core concrete, dry film thickness (DFT) of intumescent coating, and steel section thickness are the primary determinants of the temperature rise of the protected CFSC section under fire considered in the developed models. This study adds large-scale column specimens to the corresponding numerical database. The numerical results provide additional proof that a CFSCs coated with an intumescent fire coating can achieve high fire resistance. With efficient IFC insulation and core concrete heat absorption, the temperature increase of a CFSC can be greatly retarded.