Measurement of the compressive strength of parallel strand lumber (PSL) is conducted on specimens of varying size with nominally identical mesostructure. The mean of the compressive strength is found to vary inversely with the specimen size, and the coefficient of variation of the strength is found to decrease with increasing specimen size, and to be smaller than the coefficient of variation of strength for solid lumber. The correlation length of the compressive strength is approximately 0.5 m, and this correlation length leads to significant specimen-to-specimen variation in mean strength. A computational model is developed that includes the following properties of the PSL mesostructure: the strand length, the grain angle, the elastic constants, and the parameters of the Tsai-Hill failure surface. The computational model predicts the mean strength and coefficient of variation reasonably well, and predicts the correct form of correlation decay, but overpredicts the correlation length for compressive strength, likely because of sensitivity to the distribution of strand length used in the model. The estimates of the statistics of the PSL compressive strength are useful for reliability analysis of PSL structures, and the computational model, although still in need of further development, can be used in evaluating the effect of mesostructural parameters on PSL compressive strength.

}, keywords = {Composite lumber, Measurement, Mechanics, Probability, Random processes, Simulation, Strength, Wood}, issn = {0733-9399}, doi = {10.1061/(ASCE)EM.1943-7889.0000079}, author = {Arwade, Sanjay R. and Winans, Russell and Clouston, Peggi L.} } @article {11229, title = {Measurement and stochastic computational modeling of the elastic properties of parallel strand lumber}, journal = {Journal of Engineering Mechanics}, volume = {135}, year = {2009}, month = {09/2009}, pages = {897-905}, chapter = {897}, abstract = {This paper describes a model for the spatial variation of the elastic modulus of parallel strand lumber (PSL) that is based on bending experiments and also describes a validated stochastic computational model that incorporates orthotropic elasticity and uncertainty in strand geometry and material properties. The PSL exhibits significant variability both within members and between members, but this variability is less than that of equivalent sawn-wood members, and decreases with increasing member size. The correlation length of the elastic modulus is found to be several meters and is independent of the cross-sectional size. The variance of PSL elastic modulus is found to scale inversely with the number of strands in the cross section. The validated computational model is flexible enough to allow preliminary exploration of the properties of new mixes of species and strand sizes in PSL material design.

}, keywords = {Computation, elasticity, Laminated wood, Measurement, Mechanics, Probability, Random processes, Stochastic models, Wood}, issn = {0733-9399}, doi = {10.1061/(ASCE)EM.1943-7889.0000020}, author = {Arwade, Sanjay R. and Clouston, Peggi L. and Winans, Russell} }