Comparative study of passive fire protection design for FR355 H-section steel columns

This study investigates the fire resistance performance of H-section steel columns fabricated from fire-resistant steel (FR355) under various loading conditions. Through a combination of fire testing and finite element (FE) analysis, the relationship between axial load ratio and the critical temperature of FR355 columns is established, providing foundational data for fire safety engineering. Furthermore, three fire protection design approaches: (1) unloaded condition, (2) loaded condition, and (3) performance-based structural fire design are comparatively assessed to evaluate their efficiency in reducing the required thickness of spray-applied fire-resistive materials (SFRM). A performance-based design scenario is demonstrated using a representative case study of an H-section column exposed to a realistic electric vehicle (EV) fire in an open car park structure. The results highlight the potential of FR steels to achieve adequate fire resistance with significantly reduced fireproofing demand, particularly under loaded and performance-based strategies.