ISO/TR 24679-5:2023

This document provides a fire engineering application relative to the fire resistance assessment of a multi-storey timber building according to the methodology given in ISO 24679-1. In an attempt to facilitate the understanding of the design process presented herein, this document follows the same step-by-step procedure as that given in ISO 24679-1. The fire safety engineering approach is applied to a multi-storey timber building with respect to fire resistance and considers specific design fire scenarios, which impact the fire resistance of structural members. A component-level (member analysis) approach to fire performance analysis is adopted in this worked example. Such an approach generally provides a more conservative design than a system-level (global structural) analysis or an analysis of parts of the structure where interaction between components can be assessed. An advantage of the component-level approach is that calculations can be done with the use of simple analytical models or spreadsheets. Advanced modelling using computational fluid dynamics is presented to replicate an actual office cubicle fire scenario and for assessing timber contribution to fire growth, intensity and duration, if any. The thermo-structural behaviour of the timber elements is assessed through advanced modelling using the finite element method. The fire design scenarios chosen in this document are only used for the evaluation of the structural fire resistance. They are not applicable for assessing, for example, smoke production, tenability conditions or other life safety conditions.