Abstract: Dimensional lumber subjected to structural load regimes, where moment is the dominate load condition, usually fail structurally by initial localized compressive failure located at or near the maximum compressive extreme fiber. Said localized compressive failure, exhibited by buckling failure of maximum compressive fiber, results in an overall increase of section-modulus. The increase in section modulus, due to onset of structural failure, allows the lumber element in question to provide post-structural-failure increase in load-carrying-capacity with the trade-off of an increase in load-vs-deflection ratio. Said increase in load-carrying-capacity due to the increase in section-modulus, or thickening of the lumber element continues as an applied load is increased until the lumber element's tensile extreme fiber's capacity is exceeded, at which event the lumber element structurally fails catastrophically.