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

L = panel span (mm)= cross-sectional area of all stringers and T flangesA(mm 2 )G = modulus of rigidity of stringers (N/mm 2 )Top skin deflection for plywood panels with skins each side, resulting in the top skinfunctioning as a fixed ended beam when spanning across stringers:wherew∆I44 w = (11.5)384 E It= panel load in kPaE tBending StressesTo check the bending capacity of the panel may require:= clear span between stringers (mm);= second moment of area of a unit width of topskin perpendicular to the direction of spanningof the stringers;= modulus of elasticity for top skin (MPa).re-evaluation of panels section properties if the clear distance () between stringers is>b (see FIGURE 11.3) for either or both skins thus requiring a reduction in the effectivewidth of skin/s;for single skin/panels, if >b the effective width will be the sum of the stringer widthsplus 0.25b on each side.MyEF b , =a (11.6)EI gwhere M = the bending moment on the panel at the sectionconsidered;y = the distance from the neutral axis to the fibreunder consideration;E = MoE of the element being considered;EI = the flexural rigidity of the panel.gWhere such information is available, and if it is applicable, the necessary increase in maximum stress in thestringers and plywood skins should be made to account for shear lag.FIGURE 11.5 shows a typical stress distribution for the plywood skins and stringers of a stressed skin panel.148