Fire tests of full-scale LSF floor systems

Abstract

Light gauge steel frame (LSF) floor-ceiling systems, constructed from cold-formed steel members, provide lightweight and cost-effective solutions. However, their performance can be significantly compromised by fire, which reduces their load-bearing capacity and fire resistance levels (FRL). The initial phase of this research investigated the behaviour of LSF floors using short-span fire tests, which was followed by standard fire tests of full-scale LSF floor assemblies, aimed at determining the FRLs of commonly used floor configurations. The full-scale test series comprised two ambient temperature tests and three standard fire tests. This study has shown that adding an extra 16-mm gypsum plasterboard layer to a non-insulated assembly increased the FRL by 66 %, and employing a steel-concrete composite deck flooring enhanced the FRL by 32 %. It has provided plasterboard fall-off temperatures and times for developing a fall-off criterion in numerical studies. The findings revealed that short-span fire tests, while conservative in terms of failure times, produced FRLs comparable to those from full-scale standard fire tests, suggesting they are a cost-effective and time-saving method for verifying the FRLs of existing and new floor configurations. This research has provided suitable design recommendations including the FRLs of 16 LSF floor configurations, delivering valuable guidance to fire engineers.