On Fracture-Related Causes for Reduction in Tensile Strength of Southern Pine Lumber at Low Moisture Content

A combination of lumber testing and finite element-fracture mechanics simulation was used to determine the influence of moisture content on the tensile strength of southern pine dimension lumber. This research confirmed that tensile strength degrades as equilibrium moisture content drops below 12%. The simulations allowed tracking of the individual influence of different clear wood properties on the tensile strength of lumber specimens. The finite element results suggest that lumber containing knots more closely approaches idealized linear elastic behavior as the wood becomes extremely dry. For green lumber, the model appears to be overly conservative, possibly because stress concentrations are reduced by inelastic response perpendicular to the grain