Typical applications in which structural plywood is loaded normal to the face include flooring, cladding,
bridge decking, trafficable roofs, and signboards.
Section Properties – Standard Plywood Layups
Section properties for standard plywood constructions
loaded normal to the plane of the plywood panel, are
given with respect to the orientation of the plywood
face grain direction relative to the span direction. The
face veneer grain direction of structural plywood
panels usually runs in the panel length direction.
Thicker veneers, further from the panel neutral axis
and with grain direction parallel to span, will be the
major contributors to I, and therefore to both
bending strength and stiffness.
TABLE 5.3 gives section properties for plywood
loaded normal to the plane of the plywood
panel. These are for standard thicknesses and
constructions of structural plywood specified in
AS/NZS 2269 together with some additional
thicknesses made by some manufacturers. A
method for calculating the section modulus
(Z) and second moment of area (I), for
structural plywood loaded normal to the face,
is detailed in Appendix J of AS1720.1–1997
Timber Structures Code. This Appendix is
reprinted in Appendix 0
of this manual.
Load Distribution Width
When calculating strength and stiffness capacities for concentrated loads applied normal to the plywood
face, it is necessary to determine the distribution width of the concentrated load across the plywood
sheet width. Load distribution widths established from testing conducted by the EWPAA*, and used in
calculating EWPAA span/deflection tables for structural plywood flooring, are reproduced in TABLE 5.2.
Distribution Width (mm)21
12 – 13
15 – 19
20 – 25
TABLE 5.2: Load Distribution Widths
*Other methods for establishing load distribution width are used, including formula based on the ratio of the I values for veneers parallel to
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