Best practices for modeling structural boundary conditions due to a localized fire

Abstract

Summary Recent studies suggest the assumption of uniform heating that is used in current structural fire design cannot be assumed conservative, especially if the fire is expected to burn locally. Aside from design equations, which have limited applicability, a common approach to simulating structural members subjected to a localized fire is modeling the fire‐structure interaction using a coupled computational fluid dynamics (CFD)‐finite element (FE) model. In the existing literature, a wide range of methods and parameters are used when determining the boundary conditions at the fire‐structure interface, specifically regarding the representation of net heat flux, heat transfer coefficient, and surface emissivity of steel. The purpose of this study is to investigate various methods for representing the boundary conditions in terms of accuracy and computational efficiency and then identify best practices. In conclusion, our study found that net heat flux predicted by adiabatic surface temperature, a nonconstant heat transfer coefficient, and a surface emissivity of 0.9 for steel was the most reliable thermal boundary condition in a coupled CFD‐FE model of a localized fire. These recommendations are based on the two cases studied here, and caution should be used when applying these results to future studies.

Advancements in evaluating the fire resistance of structures

“…After stringent peer review, 12 of the 17 oral presentations are presented here as full papers. The papers accepted for this issue were on the following topics[5][6][7][8][9][10][11][12][13][14][15][16] :Due to modern developments in the construction materials industry, to ensure design safety, we are being challenged with requiring significant understanding of new materials and their performance in fire. Since 1918, the standard fire time-temperature curve has been utilized to assess the fire resistance of building materials.…”

“…After stringent peer review, 12 of the 17 oral presentations are presented here as full papers. The papers accepted for this issue were on the following topics: Comparative Energy Analysis from Fire Resistance Tests on Combustible vs Non‐combustible Slabs The Discrepancies in Energy Balance in Furnace Testing, a Bug or a Feature? A New Test Methodology for Studying the Response of Walls to Real Fire Environments Simulating Real Compartment Fire Conditions in a Furnace Rectification of “Restrained vs. Unrestrained” Fire Resistance of Cold‐formed Steel Framed Shear Walls under various Fire Scenarios Development and Application of a Simulation Approach for Fire and Structure Interaction of Concrete Members subject to Spalling Test Methods for Characterizing Concrete Properties at Elevated Temperatures Evaluation of Standard and Real Fire Exposures on Thermal Response of Rail Car Floor Assembly Best Practices for Modeling Structural Boundary Conditions Due To a Localized Fire Flame Extension and the Near Field under the Ceiling for Travelling Fires Inside Very Large Compartments An Extended Travelling Fire Method (ETFM) Framework for Performance‐based Structural Design …”