Shear behaviour of fixings in sheathed light steel wall panels

Abstract

The performance of screwed connections in sheathed cold-formed steel frames was investigated in this study through push-out testing of specimens representative to wall panels sheathed with cement-based boards. An extensive experimental programme was carried out, focusing on parameters including fixing diameter, loading conditions, sheathing material and the effect of wings at the tip of the fixing. Measured characteristics such as peak connection load and stiffness were obtained for each specimen type. Failure modes comprising of bearing, tilting, and pull-through were consistent amongst the tested specimens. Those sheathed with calcium silicate boards showed that the respective connections can achieve higher peak loads and stiffness compared to fibre-cement sheathed specimens. The removal of wings from the tip of the fixing resulted in increased thread engagement on the board material as the hole was not enlarged by the wings. This was identified as a significant factor, leading to increased shear resistance and stiffness, with some of the fibre-cement specimens performing comparably to those using calcium silicate boards and winged fixings.