Modelling the influence of steel structure compartment geometry on travelling fires

Abstract

The response of structures exposed to fire is highly dependent on the type of fire that occurs, which is in turn very dependent on the compartment geometry. In a European research project, computational fluid dynamics simulations were carried out to analyse the influence of compartment geometry and the interaction with representative fuel loads to explore the conditions leading to the development of a travelling fire. The influence observed of ceiling height, crib spacing and opening geometry in controlling spread rates tended to confirm the possibility of predicting the occurrence, or not, of a travelling fire. The results of one analysis were then used to perform a non-linear thermo-mechanical analysis of a steel structure. It was possible to use the radiative intensities and gas temperatures obtained with a computational fluid dynamics model to calculate with a finite-element model the temperatures in structural elements located in the compartment, and to evaluate the structural behaviour of a frame made of these elements. This paper therefore highlights the effect of building design specifications on the temperature development and on the resulting mechanical behaviour of a steel structure where the travelling nature of a fire has been considered comprehensively.