Probabilistic structural fire engineering using incremental fire analysis and cloud analysis

Abstract

Probabilistic structural fire engineering is an approach to designing structures for fire conditions, which allows the estimation of an annual rate of exceeding various levels of building response. This is done by combining the annual rate of exceeding various fire exposure conditions with probabilistic relationships between structural response and fire severity. One available method that has been used to quantify this relationship is incremental fire analysis (IFA). Another approach which is well-established in earthquake engineering but has so far not been explored in fire engineering is cloud analysis (CA). This paper compares how well both methods estimate structural response under fire conditions and their associated probabilities of exceedance of a specified level of structural response. The paper demonstrates the inner workings of the two methods and their application and also proposes recommendations for their application to structural fire engineering. It is demonstrated with the help of a case study of a composite steel beam exposed to a suite of fires, generated by considering fuel load and ventilation as random variables. CA is found to be computationally less demanding than IFA, yet both approaches produce similar probability of exceedance of various levels of structural response.