Accurate 3D numerical models towards the prediction of the fire resistance on LSF partition walls

This comprehensive computational study develops and validates three-dimensional numerical models to analyse the fire performance of non-load-bearing Light Steel Frame (LSF) under standard ISO 834 and more severe hydrocarbon fire scenarios. The research employs three distinct computational methods to predict fire behaviour in LSF walls with void cavities, utilising medium-scale experimental data for validation purposes. The finite element method is employed for transient thermal analysis, incorporating temperature-dependent effective material properties and simulating material degradation processes. The validation process showed good agreement between the numerical predictions and experimental results, demonstrating the need for modifications in the effective thermal properties of mineral wool when this material is submitted to hydrocarbon fire. Extensive parametric analyses are conducted to explore the influence of critical factors such as gypsum board properties and mineral wool insulation density on the fire resistance of LSF walls. The results indicate that increasing gypsum thickness significantly enhances fire resistance—approximately 12–21 min per additional millimetre, depending on fire type—while higher insulation density contributes modestly. Hydrocarbon fires reduced fire resistance by an average of 57 % compared to ISO 834 fires for cavity-insulated walls, whereas external insulation configurations showed less reduction. New empirical formulas were proposed to estimate insulation fire resistance based on gypsum thickness, insulation density, and fire scenario, with high correlation to numerical results. The study highlights the importance of accurate cavity heat transfer modelling and material degradation representation for reliable fire performance prediction of LSF walls. These validated numerical tools support improved design and safety assessment of LSF partition walls under realistic fire conditions, including severe hydrocarbon fires, thereby advancing fire safety engineering for modern LSF constructions.