Racking Strength of Walls: Let-in Corner Bracing, Sheet Materials, and Effect of Loading Rate.

摘要

Theoretical and actual racking strength of panels sheathed with fiberboard were closely correlated. Also the dispersion or variability in the data was within normal limits expected for wood-base material. The equations for computing racking strength are independent of panel size, so both simple lateral nall tests and small-scale racking tests could augment the more expensive full-size panel tests. The actual performance of let-in corner braces, without the horizontal board sheathing, is well below the 5,200-pound level cited in the Federal Housing Administration Technical Circular No. 12. Although the strength and stiffness of the brace are important, a level is reached where the stud frame controls ultimate strength. The rate of loading does affect ultimate load for both lateral nall and racking tests. Results of this study, which indicated an 8 to 9 percent increase in strength with a tenfold increase in speed, agree with past studies on the effect of loading rate on strength of wood and wood-base materials.