Racking strength of walls : let-in corner bracing, sheet materials, and effect of loading rate

Abstract

Determination of the racking strength of wails, which is a measure of a building system’s ability to resist wind loads, has generally been limited to performance testing. Although a standard test method exists, deviations have often been made in speed of testing and panel configuration. The purpose of this study was to determine the relative effect of some of these deviations on test results. In addition, the racking strength of wails with let-in corner braces, which forms the basis for acceptance criteria, was evaluated. Strength of wails with let-in corner braces, but without horizontal board sheathing, averaged less than 2/3 of the 5,200 pound value specified by FHA. Walls sheathed with fiberboard correlated well with theoretical strengths calculated using a recently developed equation. A tenfold change in rate of loading for small scale racking and lateral nail tests changed the strength 8 to 9 percent. Similar results would be expected for full size tests. The standard and modified test procedures used will be helpful in assessing the present test procedure and the feasibility of augmenting it with small-scale racking and lateral nail resistance tests. The evaluations conducted for this study are not to be interpreted as qualification tests for any of the materials involved.

Citation

Tuomi, Roger L.; Gromala, David S. 1977. Racking strength of walls : let-in corner bracing, sheet materials, and effect of loading rate. Res. Pap. FPL-RP-301. Madison, WI : U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 20 pages