Fire resistance of a damaged building employing buckling restrained braced system

This study investigates the influence of buckling restrained brace systems (BRBs) on the overall structural stability against fire following a severe incident, which caused the failure of a column on the first storey of a steel building. A four-storey moment frame fitted with the inverted-V arrangement of braces is modelled, considering a multi-hazard approach. This technique concentrates on a structural plane frame that is designed to meet the progressive collapse criteria according to the U.S. Department of Defense guidelines and assumes that an extreme event damaged a first-storey centre column, before the exposure to an ensuing fire. The performance of BRBs in preventing the global collapse of the structure due to a post-event fire is compared with that of ordinary concentric brace systems (OCBs). The results indicate that BRBs offer a higher global collapse time to the building owing to the greater stiffness they provide to the structural frame. The fire resistance provided by BRBs is restricted to the participation of bracing elements and framing girders afterwards. In the case of OCBs, columns contribute to the structural resistance prior to the full capacity of braces used. To conclude, it is found that BRBs are more capable in maintaining the stability of a damaged building against fire resulting from an extreme event than OCBs.