Method for Simulating Tension Performance of Lumber Members

Abstract

A methodology is described for simulating the tension performance of lumber members. The described methodology uses detailed knowledge of individual board three‐dimensional fiber orientation in a finite element model to predict the fracture behavior that occurs in lumber. Grain‐angle data maps were obtained using previously developed nondestructive measurement techniques and small clear‐wood specimen property tests were conducted to provide model input. In addition to fracture patterns, the methodology accurately predicts the tensile strength of lumber specimens without the aid of empirical adjustment factors. The computational characteristics of the fracture‐related aspects of the model are described. Sample experimental observations are provided, showing the accuracy of the method for predicting fracture patterns, load‐displacement response, and tensile strength of lumber specimens. It is hoped that this methodology will lead to a new fundamental basis for grading lumber and determining allowable design stresses. Discussion is provided on those material characteristics, including within‐board grain‐angle and property variations that make lumber performance difficult to predict.