Page 235 - Civil Engineering Formulas

TIMBER ENGINEERING FORMULAS 169

The beam stability factor C may be calculated from
L
*
1 (F bE /F b ) * 2 *
C L 1 (F bE /F b ) F bE /F b (6.34)
1.9 B 1.9 0.95
*
where F b design value for bending multiplied by all applicable adjustment
factors, except C , C , and C L
V
fu
2
F K bE E /R B
bE
0.438 for visually graded lumber and machine-evaluated lumber
K bE
0.609 for products with a coefficient of variation of 0.11 or less
E design modulus of elasticity multiplied by applicable adjustment
factors

FASTENERS FOR WOOD

Nails and Spikes

The allowable withdrawal load per inch (25.4 mm) of penetration of a common
nail or spike driven into side grain (perpendicular to fibers) of seasoned wood,
or unseasoned wood that remains wet, is

5/2
p 1,380G D (6.35)
where p allowable load per inch (mm) of penetration into member receiving
point, lb (N)
D diameter of nail or spike, in (mm)
G specific gravity of wood, oven dry
The total allowable lateral load for a nail or spike driven into side grain of
seasoned wood is
p CD 3/2 (6.36)

where p allowable load per nail or spike, lb (N)
D diameter of nail or spike, in (mm)
C coefficient dependent on group number of wood (see Table 6.1)
Values of C for the four groups into which stress-grade lumber is classified are
Group I: C 2,040
Group II: C 1,650
Group III: C 1,350
Group IV: C 1,080