Wall Stud-to-Track Gap: Experimental Investigation

Because of an increasing interest in the use of cold-formed steel for commercial and residential framing, both design and installation guidelines are needed. The wall framing, which typically consists of axial load bearing C-section studs, is laterally braced and attached at the bottom and top of the wall to a track section. The common bottom and top attachment consists of the wall stud and track of nominally the same cross-section depth. Because the nominal depths of the C-section and the track are similar, a tight connection is often not achieved and a gap occurs. The Standard for Cold-Formed Steel Framing—General Provisions specifies that the gap between the wall stud and track in a wall assembly must not exceed $1∕8\mathrm{in.}$ This gap dimension is consistent with the gap specified by ASTM C 1007. The value of $1∕8\mathrm{in.}$ is based on industry experience and practice but had not been experimentally verified. To explore both the stud-to-track connection strength and the aesthetic concerns associated with a gap between the axial load bearing stud and the track in a typical cold-formed steel wall assembly, a test program was initiated at the University of Missouri-Rolla. Based on the findings of the 54 wall assembly tests and short column tests performed in this experimental study, design guidelines are proposed for a typical wall stud assembly.