Framework for a performance-based analysis of fires following earthquakes

Most current structural fire codes focus on achieving prescribed fire ratings, which are based on standard fire tests with minor relevance to what is required for fire safety. These prescriptive design approaches do not provide sufficient information regarding the performance of structural members or systems under elevated temperatures. Furthermore, the limited structural design provisions provide no indication of the level of reliability of structures since comprehensive treatment of the uncertainties associated with the hazard is not considered. It is therefore imperative to move towards performance-based engineering not only to quantify structural reliability for given performance objectives but also to ensure more economic and safe design. This paper provides details on the development of a new analysis framework for probabilistic performance-based analysis of a fire following an earthquake. The framework is then utilized to develop fragilities of steel structural members and systems subjected to cascading hazards of earthquake and fire while considering buckling of columns as the damage limit state. Uncertainties associated with fire hazard, passive fire protection, gravity load, and earthquake intensity are accounted for in the framework. The proposed performance-based approach for the analysis of a fire following an earthquake can be considered an extension of the Pacific Earthquake Engineering Research (PEER) performance-based earthquake engineering framework and used by engineers to assess structural performance under the multiple hazards.