Behaviour of steel frames under fire conditions

A state-of-the-art review of the behaviour of steel frame structures in fir e is presented. Results from different studies indicate that the behaviour of a complete structure is different from that of a single structural membe r under fire conditions from the point of view of fire resistance. Earlier studies also show that analysis and design of steel structures against fire based on their overall behaviour could lead to a reduction or the eliminat ion of applied fire protection to certain structural members. The effects o f continuity, restraint conditions, and load ratio on the fire resistance o f frame structures are discussed. The beneficial aspects derived from consi dering overall structural rather than single-member behaviour in fire are i llustrated through the analysis on two one-bay, one-storey, unprotected ste el portal frames, a column, and a beam. Also comparison is made between the performance of a beam with different end restraints in fire. Results from the analyses indicate that the fire resistance of a member is increased whe n it is considered as part of a structure compared with when it is consider ed as a single member.