Fire Resistance of Steel C-Joist Floor Assemblies

Abstract

This paper discusses the factors that affect the fire resistance performance of lightweight steel-framed (LSF) unrestrained floor assemblies protected with Type X gypsum board ceiling finishes. Sixteen fire resistance experiments were conducted on full-scale load-bearing steel C-joist floor assemblies using the ULC standard fire exposure time–temperature curve that is similar to ASTM E119 standard. Parameters investigated in this study include the effects of insulation installation, insulation type, joist spacing, resilient channel installation, resilient channel spacing, type of sub-floor layer and number of sub-floor layers versus number of gypsum board layers. The impact of these parameters on the fire resistance of steel C-joist frame floor assemblies is discussed. The fire resistance of LSF floors appears to be essentially governed by the number of gypsum board layers, spacing of the joists or resilient channels where the gypsum boards are attached, sub-floor type and insulation type. Other parameters are of secondary importance.