EVALUATION ON FAILURE PROBABILITY OF A PROTECTED STEEL BEAM THAT SATISFIES REQUIRED FIRE RESISTANT PERFORMANCE BASED ON A FIRE RESISTANT PERFORMANCE-EVALUATION TEST

Regarding practical fire resistant designs for steel structures in Japan, the performance-based design represented by the AIJ Recommendations for Fire Resistant Design of Steel Structures is rarely used, on the other hand, the specification-based design code (route A) on the Building Standard Low of Japan is widely applied to determine specification of fire proofing material used for the steel member, which has been verified by the fire resistant performance-evaluation test (hereinafter referred to as fire test). The fire test condition differs from the actual condition of fully-developed compartment fire occurred in a building, in particular, regarding the fire temperature and time relationships, the boundary and loading conditions for the heated steel member. Furthermore, the fire loads in the compartment room, mechanical properties of steels at elevated temperatures, and dead and live loads applied to the member possess the large dispersion. To evaluate the safety side performance of protected steel beam based on the specification-based design code, the large loading values at the fire test are used in comparison with the actual condition, however, that probabilistic fire safety at the fully developed compartment fire has not been clarified. To improve the fire resistant safety of the protected steel members applied for many steel buildings, the reliability evaluation on the specification-based design code is of importance.