Numerical study of LSF walls made of cold-formed steel hollow section studs in fire

Abstract

Cold-formed steel square and rectangular hollow section (SHS/RHS) studs are often used to replace the conventional lipped channel section studs in light gauge steel frame (LSF) wall systems to meet the required high load demand. To ensure adequate structural fire resistance of SHS/RHS stud walls, four full-scale fire tests were previously completed under standard fire conditions. However, the full-scale fire tests are expensive and time-consuming, while the complex fire performance cannot be adequately explained through test observations and results alone. Hence, a numerical study was undertaken by developing simplified and sheathed stud finite element (FE) models of tested walls. This paper provides the details of the developed models of LSF walls made of SHS/RHS studs at both ambient and elevated temperatures and a comparison with experimental results. The validated models were used to highlight the advantage of using SHS/RHS studs in cavity insulated stud walls and further understand the factors that may affect the fire resistance of LSF walls, such as steel grade and stud depth. In addition to the simplified stud model, advanced modelling techniques were used to explore the effects of sheathing and localised plasterboard fall-off on the wall behaviour in fire. Overall, this paper presents a numerical study of SHS/RHS stud walls and the simplified stud model developed in this paper can be used to predict the fire performance of other SHS/RHS stud walls with similar wall configurations.