1996 LRFD Supplements - unprotected PDF - American Wood Council

LRFD STRUCTURAL LUMBER SUPPLEMENT35Table 4.3 Size Factor, C F1,2,3F bNominal ThicknessGrades Width 2" & 3" 4" F tF c4" & less 1.5 1.5 1.5 1.15Sel. Struct., 5" 1.4 1.4 1.4 1.1No. 1 & Btr., 6" 1.3 1.3 1.3 1.1No. 1, No. 2, 8" 1.2 1.3 1.2 1.054No. 3 10" 1.1 1.2 1.1 1.012" 1.0 1.1 1.0 1.0$14" 0.9 1.0 0.9 0.94" & less 1.1 1.1 1.1 1.05Stud 5" & 6" 1.0 1.0 1.0 1.08" & wider Use No. 3 grade base values and size factorsConst. Stand. 4" & less 1.0 1.0 1.0 1.04" 1.0 1.0 1.0 1.0Utility2" & 3" 0.4 --- 0.4 0.6DESIGN ADJUSTMENT FACTORS1For Southern Pine and Mixed Southern Pine dimension lumber (reference strengths in Table 3.2), the value of C F is 1.0 for all properties and all sizes 12" in widthand less, except for material 4" in thickness and 8" and wider, where C F is 1.1 for F b .2For mechanically graded dimension lumber (both MSR and MEL, reference strengths in Table 3.1), the value of C F is 1.0 for all properties and all sizes.3For members with reference strength values listed in Table 3.3, C F for F b is computed as (12/d) 1/9 $ 1.0, where d is the depth of the member. C F for other propertiesis 1.0".