Evaluating the effects of travelling fires on entire compartment spaces

Modern architectural plans have increasingly diverged from conventional designs characterized by small enclosures, favouring open-plan layouts that result in significantly larger compartment sizes. These open-plan designs offer various advantages, including enhanced social interaction, improved communication, and aesthetic benefits within the building layout. However, despite these benefits, such designs pose considerable challenges to fire safety for both occupants and infrastructure. Current fire safety design approaches are typically based on standard fire scenarios that assume uniform temperature distributions or rely on zone models. These methods are inadequate for capturing the complex behaviour of fires in large, open compartments. In large compartments, accidental fires tend to ignite locally and spread progressively across the floor space. Contrary to current assumptions, these fires are highly transient and can be sustained for extended durations. Such travelling fires have been studied in detail during the TRAFIR project, led by the authors. While the project has produced several publications on travelling fires, the existing studies primarily focus on localized behaviour within the fuel bed and along the direction of fire spread. The broader impact of travelling fires on entire compartment spaces and the structural system as a whole, remains insufficiently understood. This study addresses this knowledge gap by investigating the influence of travelling fires on large, open-plan compartments. The results are presented in terms of recorded gas temperatures throughout the compartment and the thermal response of structural elements, specifically steel beams and columns, located at various distances from the fire origin. The findings reveal the transient nature of travelling fires and significant thermal variation across the compartment. These temperature differences influence the structural performance, causing some elements to lose strength and stiffness while others retain their load-bearing capacity. Overall, the study offers critical insights into structural behaviour under travelling fire conditions and provides a foundation for more resilient fire safety designs in modern open-plan buildings.