The significance of slab for structural response under travelling fires

Zhuojun Nan, Xu Dai*, Stephen Welch, Asif Usmani

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review


The role of “travelling fires” is to ensure the robustness of structural design with large compartments under realistic fires, having a fire plume at the near-field, and a hot smoke layer preheating the ceiling at the far-field. Once the fire travels, the near-field has a leading edge representing the fire spread, and a trailing edge representing the burnout of the fuel. Though well understood by its definition, the mainstream of efforts on travelling fires for structural response is limited to 2D finite element modelling (FEM). This paper aims to identify the importance of slab inclusion with a 3D FEM structural model for steel-composite structures under travelling fires, with a special emphasis on the significance of ignoring the slab structural capacity contribution from a 2D simplified structural model. The role of fire protection scheme for 2D model against the 3D model on numerical predictions was also explored. It was found that the structural load path, and the potential structural failure mechanisms could be fundamentally different between the 3D model and the 2D model, i.e., with or without slabs. Although the 2D model tends to predict larger deflections (i.e. more conservative) than the 3D model, it could also significantly underestimate the large internal forces from the beams, which might overlook the connections failure under travelling fires. Further, due to the simplification of the 2D model omitting the significant stiffness contribution from the slab, the effect of the fire protection is likely to be amplified. It may be misleading for the performance-based structural fire design under different travelling fire scenarios. Hence, the 3D model is likely to be considered as necessary and feasible for structural fire analysis for travelling fires as a complement to the 2D model approach.
Original languageEnglish
Title of host publicationProceedings of the 12th International Conference on Structures in Fire
Subtitle of host publicationHosted by The Hong Kong Polytechnic University
EditorsLiming Jiang, Paulo Vila Real, Xinyan Huang, Mhd Anwar Orabi, Jin Qiu, Tianwei Chu, Zhuojun Nan, Cheng Chen, Zhiruoyu Wang, Asif Usmani
PublisherThe Hong Kong Polytechnic University
Number of pages12
ISBN (Print)978-962-367-869-8
Publication statusPublished - 2023
Externally publishedYes
EventSiF 2022 - The 12th International Conference on Structures in Fire - Hong Kong Polytechnic University, Hong Kong, Hong Kong
Duration: 20 Nov 20222 Dec 2022


ConferenceSiF 2022 - The 12th International Conference on Structures in Fire
Abbreviated titleSiF 2022
Country/TerritoryHong Kong
CityHong Kong
Internet address


  • Travelling fires
  • 3D FEM
  • steel composite structure
  • performance-based design


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