Building Design and Construction Handbook - Merritt - Ventech!

10.12 SECTION TEN
Cr � repetitive member factor—applicable only to dimension-lumber beams
2 to 4 in thick (Art. 10.5.8)
Cc � curvature factor—applicable only to curved portions of glulam beams
(Art. 10.5.9)
Cƒ � form factor (Art. 10.5.10)
For glulam beams, use either CL or CV, whichever is smaller, not both, in Eq. (10.1).
The adjusted design value for tension F�t is given by
F� � FC C CC (10.2)
t t D M t F
where F t � design values for tension.
For shear, the adjusted design value is computed from
F� V
F� � FCC CC (10.3)
V V D M t H
where FV � design value for shear and CH � shear stress factor � 1—permitted
for FV parallel to the grain for sawn lumber members (Art. 10.5.13).
For compression perpendicular to the grain, the adjusted value F�c� is obtained
from
F� � F C CC (10.4)
c� c� M t b
where F�c� � design value for compression perpendicular to the grain and Cb �
bearing area factor (Art. 10.5.11).
For compression parallel to the grain, the adjusted design value F�c is given by
F� � FC C CCC (10.5)
c c D M t F p
where Fc � design value for compression parallel to grain and Cp � column stability
factor (Arts. 10.5.11 and 10.8.1).
For end grain in bearing parallel to the grain, the adjusted design value F�g is
computed from
F� � FC C (10.6)
g g D t
where F g � design value for end grain in bearing parallel to the grain. See also
Art. 10.11.1.
The adjusted design value for modulus of elasticity E� is obtained from
E� � EC C C (10.7)
M t T
where E � design value for modulus of elasticity
C T � buckling stiffness factor—applicable only to sawn lumber truss compression
chords 2 � 4 in or smaller, when subject to combined bending
and axial compression and plywood sheathing 3 ⁄8 in or more thick is
nailed to the narrow face (Art. 10.5.12).
10.5.1 Load Duration Factor
Wood has the capacity to carry substantially greater loads for short periods of time
than for long periods. Design values described in Art. 10.3 apply to normal load
duration, which is equivalent to application of full design load for a cumulative