Computational methodology for investigating the fire behavior of modular steel buildings using full-scale testing and coupled CFD-FEM analysis

This study proposed a computational methodology that combined full-scale fire testing and coupled computational fluid dynamics-finite element method (CFD-FEM) analysis to precisely evaluate the fire behavior of modular steel buildings. Conventional fire resistance assessments conducted at the individual component level do not adequately consider interactions between modules and incur high costs and time requirements, making them unsuitable for evaluating modular buildings. To address this, a full-scale fire test was conducted in accordance with the LPS 1501-1 standards. Temperatures were measured at key locations, including the floor of the upper module, walls of side modules, the inside of center module, and critical structural members. However, due to the limitations in real-time structural behavior measurements and the practical constraints associated with repeating full-scale modular fire tests, an alternative coupled numerical analysis model was developed. The fire spread and temperature distributions were analyzed using CFD simulations under matching conditions, and the resulting thermal fields were incorporated into FEM-based thermal analysis to evaluate the fire behavior of modular steel buildings. The analysis results were compared with experimental temperature data, in terms of maximum temperatures, to confirm general consistency. Furthermore, to estimate the structural behavior of members at elevated temperatures, the deflection of the upper module was obtained through structural analysis and compared against the failure criterion defined in LPS 1501–1. The proposed methodology offers a practical framework for assessing the fire-resistance performance of modular construction and serves as a complementary tool to address experimental limitations in full-scale testing.