Building Design and Construction Handbook - Merritt - Ventech!

10.28 SECTION TEN
10.8 WOOD COMPRESSION MEMBERS
The design of wood columns or other types of compression members requires
consideration of compressive strength parallel to the grain, end bearing, and stability,
or resistance to buckling. Compressive strength considerations are the same
regardless of the type of column, since the maximum compressive stress ƒ c induced
by loads must not exceed the design value for compression parallel to the grain,
F c, multiplied by applicable adjustment factors for service conditions (Art. 10.5).
(For design for end bearing, see Art. 10.11.1, and for stability, see Art. 10.8.1).
Wood compression members may be a solid piece of lumber or timber (Fig.
10.2a), or spaced columns, connector joined (Fig. 10.2b and c), or built-up (Fig.
10.2d).
10.8.1 Solid Columns
These consist of a single piece of lumber or timber or of pieces glued together to
act as a single member. In general,
where P � axial load on the column
Ag � gross area of column
F�c �
ƒ � P/A � F� (10.23)
c g c
design value in compression parallel to grain multiplied by the applicable
adjustment factors, including column stability factor C P
FIGURE 10.2 Behavior of wood columns depends on length-thickness or length-depth
ratios: (a) solid wood column; (b) spaced column (the end distance for condition a should
not exceed L 1 /20 and for condition b should be between L 1/20 and L 1/10); (c) shear-plate
connectors in the end-block of the spaced column; (d) built-up column.