Fragility Curves for Fire Exposed Structural Elements Through Application of Regression Techniques

The structural fire engineering community has demonstrated a growing interest in probabilistic methods in recent years. The trend towards consideration of probability is, amongst others, driven by an understanding that further advances in detailed numerical models are potentially offset by the basic uncertainty in the input parameters. Consequently, there has been a call for the development of fragility curves for fire-exposed structural elements, to support the application of probabilistic methods both in design as well as in standardization. State-of-the-art structural fire engineering models are, however, commonly very computationally expensive, even for simple cases such as isolated structural elements. This can be attributed to the requirement of coupling thermal and mechanical analyses, and to the large non-linearity in both the heating of structural elements and the resulting mechanical effects of temperature-induced degradation and strains. This severely hinders the development of fragility curves beyond very specific cases, especially when including a stochastic description of the (natural) fire exposure. In the current contribution the application of regression techniques to structural fire engineering modeling is explored, as a stepping stone towards establishing a methodology for the efficient development of fragility curves for fire-exposed structural members. A simplified model with limited computational expense is applied to allow for validation of the proof-of-concept.