MOE Distribution in Visually graded Ponderosa Pine Lumber Harvested from Restoration Programs in Southern Oregon and Northern California

Abstract

. Every year, restoration programs in Southern Oregon and Northern California produce large amounts of low-value ponderosa pine, Pinus ponderosa (PP) lumber. This material has a limited market in the United States. Engineered wood products, such as cross-laminated timber (CLT) and glulam, are expected to provide a value-added market to offset the high costs of restoration programs. However, restoration program lumber has larger amounts of juvenile wood and visual grades are reported to show lower mechanical properties compared with commercially harvested material, on which the National Design Speci fi cation (NDS) design values are based. This research addresses a knowledge gap on the impact of juvenile wood and visual strength-affecting characteristics on the mechanical performance of PP lumber generated in the region of interest. The purpose of this study was to assess this impact based on dynamically measured MOE of samples of visually graded and ungraded restoration program PP lumber. The material used in this study was intended for fabrication of CLT for another project, hence it could not be used for destructive tests to measure MOR. The results were compared with previous studies and published values for commercially harvested PP as re fl ected in the NDS Western Woods (WW) species group. The results show that characteristic MOE values of visual grade Nos. 1 and 2 of PP from restoration programs were lower than