EWPAA Structural Plywood and LVL Design Manual - Engineered ...

Identification CodeFIGURE 5.1: Parallel Ply TheoryThe plywood Identification Code provides information on the veneer arrangement within the structuralplywood. This information is required to establish the section properties of a particular plywood. TheIdentification Code gives the following information: the nominal plywood thickness, the face veneerthicknesses multiplied by 10, and the number of plies in the assembly. For example, the ID code 21-30-7describes a 21 mm thick plywood with 3.0 mm face veneer thicknesses and 7 veneer layers.5.4 Structural Plywood - Loaded Normal to the FaceTypical applications in which structural plywood is loaded normal to the face include flooring, cladding,bridge decking, trafficable roofs, and signboards.Section Properties – Standard Plywood LayupsSection properties for standard plywood constructionsloaded normal to the plane of the plywood panel, aregiven with respect to the orientation of the plywoodface grain direction relative to the span direction. Theface veneer grain direction of structural plywoodpanels usually runs in the panel length direction.Thicker veneers, further from the panel neutral axisand with grain direction parallel to span, will be themajor contributors to I, and therefore to bothbending strength and stiffness.TABLE 5.3 gives section properties for plywoodloaded normal to the plane of the plywoodpanel. These are for standard thicknesses andconstructions of structural plywood specified inAS/NZS 2269 together with some additionalthicknesses made by some manufacturers. Amethod for calculating the section modulus(Z) and second moment of area (I), forstructural plywood loaded normal to the face,is detailed in Appendix J of AS1720.1–1997Timber Structures Code. This Appendix isreprinted in Appendix 0 of this manual.Load Distribution WidthWhen calculating strength and stiffness capacities for concentrated loads applied normal to the plywoodface, it is necessary to determine the distribution width of the concentrated load across the plywoodsheet width. Load distribution widths established from testing conducted by the EWPAA*, and used incalculating EWPAA span/deflection tables for structural plywood flooring, are reproduced in TABLE 5.2.PlywoodThickness (mm)LoadDistribution Width (mm)20