ASD/LRFD Manual - American Wood Council

60 M9: WOOD STRUCTURAL PANELS
M9.1 General
Product Description
Wood structural panels are wood-based panel products
that have been rated for use in structural applications. Common
applications for wood structural panels include roof
sheathing, wall sheathing, subflooring, and single-layer
flooring (combination subfloor-underlayment). Plywood
is also manufactured in various sanded grades.
Wood structural panels are classified by span ratings.
Panel span ratings identify the maximum recommended
support spacings for specific end uses. Design capacities
are provided on the basis of span ratings.
Sanded grades are classed according to nominal thickness
and design capacities are provided on that basis.
Designers must specify wood structural panels by the
span ratings, nominal thicknesses, grades, and constructions
associated with tabulated design recommendations.
Exposure durability classification must also be identified.
Single Floor panels may have tongue-and-groove
or square edges. If square edge Single Floor panels are
specified, the specification shall require lumber blocking
between supports.
Table M9.1-1 provides descriptions and typical uses
for various panel grades and types.
M9.2 Reference Design Values
General
Wood structural panel design capacities listed in Tables
M9.2-1 through M9.2-2 are minimum for grade and span
rating. Multipliers shown in each table provide adjustments
in capacity for Structural I panel grades. To take
advantage of these multipliers, the specifier must insure
that the correct panel is used in construction.
The tabulated capacities and adjustment factors are
based on data from tests of panels manufactured in accordance
with industry standards and which bear the
trademark of a qualified inspection and testing agency.
Structural panels have a strength axis direction and
a cross panel direction. The direction of the strength axis
is defined as the axis parallel to the orientation of OSB
face strands or plywood face veneer grain and is the long
dimension of the panel unless otherwise indicated by the
manufacturer. This is illustrated in Figure M9.2-1.
Figure M9.2-1
4-ft Typical
Structural Panel with
Strength Direction
Across Supports
Panel Stiffness and Strength
Panel design capacities listed in Table M9.2-1 are based
on flat panel bending (Figure M9.2-2) as measured by
testing according to principles of ASTM D3043 Method
C (large panel testing).
Stiffness (EI)
Panel bending stiffness is the capacity to resist deflection
and is represented as EI. E is the reference modulus
of elasticity of the material, and I is the moment of inertia
of the cross section. The units of EI are lb-in. 2 per foot of
panel width.
Strength (F b S)
Bending strength capacity is the design maximum
moment, represented as F b S. F b is the reference extreme
fiber bending stress of the material, and S is the section
modulus of the cross section. The units of F b S are lb-in.
per foot of panel width.
Figure M9.2-2
Example of Structural
Panel in Bending
8-ft Typical
Strength
Direction
American Wood Council