Behaviour of stud-to-sheathing fastener connections in LSF walls at elevated temperatures

Light-gauge steel framed (LSF) walls used in low- and mid-rise buildings are usually sheathed with gypsum plasterboard to protect the thin-walled steel studs in fire. The structural failures of these walls in fire are mostly associated with local in-plane shear or pull-through failures at their stud-to-gypsum plasterboard sheathing screw fastener connections. The reductions in the mechanical properties of gypsum plasterboard and cold-formed steel studs at elevated temperatures significantly reduce the strength and stiffness provided by the stud-to-sheathing screw connections, which may lead to premature structural failure of LSF wall studs. Many detailed studies are available on the ambient temperature local in-plane response of stud-to-sheathing connections, however, the studies of both local in-plane and out-of-plane responses of stud-to-sheathing connections at elevated temperatures are limited. Therefore in this study local in-plane shear tests at elevated temperatures and pull-through tests at both ambient and elevated temperatures were conducted to determine the load?displacement behaviour, and capacity and stiffness reduction factors of stud-to-gypsum plasterboard sheathing screw connections. Suitable models of characteristic curves are also proposed to predict the in-plane and pull-through load?displacement responses of these connections at elevated temperatures. The results from this study can be used in advanced numerical analyses to optimize the design of load-bearing LSF walls under fire conditions.

Automated summary

The study focused on the local shear and pull-through responses of connections between steel studs and gypsum plasterboard sheathing in LSF walls under fire conditions. The results can be used to optimize the design and improve the fire resistance of load-bearing LSF walls.