Automated FE framework for assessing fire resistance of protected steel warehouses: Influence of secondary members and fire scenarios

This study presents a Python-based automated finite element framework for assessing the fire resistance of steel warehouse structures protected with gypsum-based systems. The proposed workflow integrating computational fire modelling with thermo-mechanical structural analysis, enabling systematic evaluation of structural performance under both standard and natural fire scenarios. The analysis focuses on the influence of secondary structural members, namely roof purlins and façade rails, considering five insulation configurations and two structural representations (multi-frame and single-frame) under different load levels. The results show that secondary members play a critical role in global structural behaviour, primarily through their contribution to stiffness and lateral restraint. Under ISO 834 standard exposure, unprotected secondary members significantly reduce failure time, with collapse occurring as early as approximately 13 min under higher load levels, whereas fully protected configurations can reach up to approximately 69 min. In contrast, under natural fire scenarios, the presence of cooling phase enables partial recovery of stiffness, allowing most protected or partially protected configurations to maintain global stability. Purlin insulation is identified as the dominant parameter governing structural performance, while façade rail protection has a secondary influence. The results also highlight the limitations of simplified design methods based on EN 1993-1-2 in capturing system-level interactions and restraint effects. The proposed framework provides an efficient tool for performance-based fire design and optimization of passive fire protection strategies in steel warehouse structures.