A flexure model and strength properties of vertically glue-laminated composites

This dissertation presents two research projects which promote more efficient use of forest resources for the manufacture and design of vertically glue-laminated composites.; The first study describes a Monte Carlo simulation model which uses beam theory, probability statistics, and statistical characterization of the mechanical properties of populations of laminations to predict the distributions of MOR and MOE of vertically glue-laminated beams of any species, grade, geometry, and number of laminations. The knowledge obtained from this research can be used to refine current methods for establishing design values and to establish strength distributions for use in reliability based design procedures.; The lamination effect was successfully modeled by quantifying load-sharing before initial failure and clear wood reinforcement up to ultimate load. The results of this research indicate that this model satisfactorily predicts the variation, and conservatively predicts the mean of composite MOR.; A sensitivity analysis identified and quantified the significant effects of eight laminar properties, including clear wood strength, laminar MOR and I{dollar}sb{lcub}rm k{rcub}{dollar} distributions, on composite MOR and MOE. The interaction between these properties was also investigated. It was suggested that additional data detailing the minimum strength ratio along lumber segments may aid in better prediction of mean composite strength.; The second study compares the mechanical properties of LVL made from interior north Douglas-fir and lodgepole pine to those of conventional LVL made from Coast Douglas-fir. Twenty-eight billets of LVL were manufactured from interior species and were sawn into samples for investigating eight mechanical properties, including MOE, MOR, and compression strength parallel to the grain. Preliminary design values were constructed for each property for comparison, on the basis of similar modulus of elasticity, with commercially available Coast Douglas-fir LVL.; LVL made from lodgepole pine with an MOE of 1,950,000 psi was found to have properties similar to that from 1.8E Coast Douglas-fir LVL. The properties of LVL made from interior north Douglas-fir (MOE = 2,220,000 psi) were similar to conventional Coast Douglas-fir 2.0E LVL.