Experimental and numerical studies on the fire-resistance behaviors of critical walls and columns in modular steel buildings

Abstract Modular steel construction (MSC) comprises off-site manufactured modules that are assembled on-site. When joining two modules together, double-layer wall systems and grouped columns are present at the junction regions, and different fire-proof measures are induced for critical walls and columns in modular steel buildings. In this study, experimental studies on the fire resistance of critical columns, load-bearing walls and non-load-bearing walls in a modular steel building were conducted to obtain the practical fire resistance performance . Temperature developments across the wall and column sections were measured and analyzed to determine the fire damage developments. The fire resistance ratings (FRRs) of different fire-proof measures were evaluated. The double-layer partition wall system and the load bearing wall system failed by the integrity failure criterion. The wall specimens all experienced the fall-off failure of fire side gypsum boards and severe ablation of the mineral wool insulation. The grouped columns with one layer of gypsum board and mineral wool insulation also experienced early gypsum board failure and a short fire-resistance rating. Based on the test results and literature reviews, suitable thermal properties for gypsum boards and mineral wool insulation were determined. The failure modeling methods for gypsum boards and mineral wool insulation were also defined. The established FE models can effectively predict the temperature developments across the section of wall and grouped column specimens. This paper provided useful fire test data for the fire proofing design of structural walls and columns in modular steel buildings, and offered rational thermal modeling methods for structural components considering the failure of commonly used fire proofing materials.