INCORPORATING SIZE EFFECTS IN THE TSAI-WU STRENGTH THEORY FOR DOUGLAS-FIR LAMINATED VENEER

This paper elucidates the need to consider the effect of volume on bri ttle material strengths when these strengths are used in a strength th eory. Specifically, Weibull weakest-link theory has been implemented w ith the Tsai-Wu strength theory to predict the ultimate load carrying capacity of a center point off-axis bending member made from Douglas-f ir laminated veneer. Weibull theory has been used in two distinct ways to account for size effects needed to evaluate brittle material stren gths (ie. tension perpendicular and parallel to grain, and shear) for the strength criterion. The analytical methods assume linear elastic, plane stress states and have been described and evaluated using probab ility theory as a framework. Analytical results are in reasonable agre ement with experimental findings substantiating the techniques propose d herein.