Treesearch

An intensive decline and mortality problem is affecting yellow-cedar trees in southeast Alaska. Yellow-cedar snags (dead trees) could be important to the economy in southeast Alaska, if some high-value uses for the snags could be established. Due to the high decay resistance of yellow-cedar, the rate of deterioration is so slow that snags may remain standing for a century or more after death. Obtaining information on wood properties from these snags is necessary to correctly assess the utilization potential of the yellow-cedar. Initial property analyses, Phase I, showed no evidence that...

This report describes the development of a test method and predictive model to estimate the residual bending strength of fire-retardant-treated plywood roof sheathing from measurement of screw-withdrawal force. The preferred test methodology is described in detail. Models were developed to predict loss in mean and lower prediction bounds for plywood bending strength as a function of a screw-withdrawal force. Our analysis of fire-retardant-treated plywood from three different studies, each with various fire-retardant-treatment, processing, plywood thickness, and exposure temperature...

As part of an effort to encourage more efficient use of small-diameter timber, the Forest Products Laboratory cooperated with Geiger Engineers in a study of the structural properties of Douglas-fir peeler cores and the efficacy of a bdowel-nutc connection detail for application in the design of a space frame roof system. A 44.5-mm- (1.75-in.-) diameter dowel-nut connector was found to be economically feasible at a design capacity of 44.5 kN (1.0 * 104 lbf) for a 127-mm- (5-in.-) diameter Douglas-fir peeler core. Variables that affect joint strength and failure mode are location of the...

Sugar maple (Acer saccharum), red maple (Acer rubrum), and yellow birch (Betula alleghaniensis) 2 by 6as were dried and evaluated for warp as it affects ability to meet softwood dimension lumber grading rule requirements for warp. In the first part of the study, sugar maple was kiln-dried to three levels of final moisture content: 27%, 19%, and 12%. Warp during kiln drying increased as final moisture content decreased. Following kiln drying, the lumber was planed and then equilibrated in 12% equilibrium moisture content conditions. Warp during equilibration generally increased as the final...

The Mohawk Canal bridge was constructed in August 1994, just outside Roll, Arizona. It is a simple-span, double-lane, stress-laminated deck superstructure, approximately 6.4 m (21 ft) long and 10.4 m (34 ft) wide and constructed with Combination 16F-V3 Douglas Fir glued-laminated timber beam laminations. The performance of the bridge was monitored continuously for 2 years, beginning shortly after installation. Performance monitoring involved gathering and evaluating data relative to the moisture content of the wood deck, the force level of the steel stressing bars, the vertical creep of...

The Lynches Woods Park bridge was constructed during the summer of 1990 in Newberry, South Carolina. It is a single-span, single-lane, stress-laminated deck superstructure that measures approximately 30 ft long, 16 ft wide, and 14 in. deep. The bridge is unique in that is one of the first known stress-laminated deck bridges to be constructed of Southern Pine lumber treated with chromated copper arsenate. The performance of the bridge was continuously monitored for approximately 3 years, beginning 10 months after installation. Performance monitoring involved gathering and analyzing data...

Properties and grade yield are estimated for structural lumber produced from No. 3, No. 4, and low-end No. 2 grade western hemlock logs of the type previously used primarily for the production of pulp chips. Estimates are given for production in the Structural Framing, Machine Stress Rating, and Laminating Stock grading systems. The information shows that significant amounts of higher grade structural lumber can be produced from these lower grade logs.

The IMPROVE Lumber Drying Program is intended to increase awareness of the lumber drying system as a critical component in the manufacture of quality lumber. One objective of the program is to provide easy-to-use tools that a kiln/predryer operator can use to maintain an efficient drying operation and therefore improve lumber drying quality. This report is one component of the IMPROVE Program. It is a guidebook1checklist for quality drying in a hardwood lumber predryer that kiln/ predryer operators or owners can use to readily evaluate how well their operations rate on those factors that...

The relationship between annual softwood sawmill production and lumber processing variables was examined using data from Sawmill Improvement Program (SIP) studies of 650 softwood mills. The variables were lumber recovery factor (LRF); headrig and resaw kerf width; total sawing variation, rough green size, and oversizing-undersizing for 4/4 and 8/4 lumber; planer allowance; and average log diameter and length. All variables except planer allowance and average log diameter were significantly influenced by annual sawmill production. The conversion efficiency of the mills in terms of most of...

Accurate modeling of the joint stochastic nature of the strength properties of dimension lumber is essential to the determination of reliability-based design safety factors. This report reviews the major techniques for obtaining bivariate distributions and then discusses bivariate distributions whose marginal distributions suggest they might be useful for modeling the joint distribution of two strength properties. Finally, we pick a bivariate Weibull distribution and show that we can write its likelihood function under a proof loading scheme, offering the possibility that it can be used to...