Addressing the pitfalls of risk-based methods for fire safety design of structures

Abstract

Risk-based design and assessment methods are gaining popularity in the context of performance-based structural fire engineering. Nevertheless, they often ignore that there exists a strong dependency between the combustion process and the structural features, impacting the structural safety assessment outcomes. This paper compares a conventional risk-based design approach with a methodology named the Maximum Allowable Consequence (MAC) approach proposed by the authors to address such a limitation. An illustrative example concerning the fire safety design of a bridge is presented. It is shown that the considered risk-based approach yields coefficients of variation on the consequence metric one order of magnitude larger than the MAC approach. Finally, this approach enables the explicit selection of the design variables that make the bridge compliant with the desired performance objectives.