Material Variability and Repetative Member Allowable Property Adjustments in Forest Products Engineering

It has been argued that repetitive member allowable property adjustments should be larger for high-variability material than for low-variability material. We report analytic calculations and simulations that suggest that the order of such adjustments should be reversed. That is, given the manner in which allowable properties are currently calculated, as the coefficient of variation of the strength distribution of individual elements increases, the upward repetitive member adjustments (if any) of assemblies constructed from these elements should decrease.