Shear resistance of gypsum-sheathed light-gauge steel stud walls

This paper presents detailed results on the shear behavior of 2.44 m by 2.44 m light-gauge steel stud walls for three different shear resisting systems: framed walls with 20 gauge flat strap X-bracing on the face--type A; framed walls with 12.5 mm (1/2 in.) single-ply gypsum wallboard on the back and 12.5 mm (1/2 in.) single-ply gypsum sheathing board on the face--type B; and framed walls with 12.5 mm (1/2 in.) single-ply gypsum wallboard on the back, 12.5 mm (1/2 in.) gypsum sheathing board on the face, and 20 gauge flat strap X-bracing on face--type C. The steel framing used in these tests is typical of framing used in residential construction. The behavior of the type A walls was governed by the yield strength of the straps with practically no resistance provided by flexure in the studs. In the type B and type C tests, the measured maximum load was controlled by the breaking of the wallboard along its edges. The failure mechanism was initiated by a rotation of the screws at the edges. This was followed by the partial pull-through of the screws at the edges of the gypsum board and simultaneous breaking of the board at the edges. Each 1.22 m by 2.44 m (4 ft by 8 ft) gypsum panel was observed to behave independently during loading. A comparison of the results from the type B and type C tests showed that the use of 50.8 mm, 20 gauge tension bracing prevented cracking of the boards at the perimeter, reduced the lateral displacement, and increased the maximum load capacity of the wall by as much as 28%.