Treesearch

To satisfy the increased demand for forest products, much of the future timber supply is expected to be derived from improved trees grown on managed plantations. This fast-grown resource will tend to be harvested in short-age rotations and will contain higher proportions of juvenile wood compared with wood in current harvests. As a result, current allowable properties may need to be reduced in the future. This report explores four options for monitoring the properties of fastgrown wood and briefly discusses the advantages and disadvantages of these approaches. The recommended multiple-stage...

More than 1,200 sawmills produce the bulk of U.S. and Canadian softwood lumber. The maps and tables in this report show the location and size of these mills by State and Province. Analysis of timber inventories in relation to use shows a close correspondence between pricing and use intensity. In some Southern States, the intensity of use is approaching recent growth levels, but the adoption of more intensive management coupled with maturing of large areas of newly established forests should increase supply over the next two decades.

Much discussion has been held regarding the merits of laboratory decay tests compared with field tests to evaluate wood preservatives. In this study, procedural aspects of soil jar decay tests with 1 cm 3 blocks were critically examined. Differences among individual bottles were a major source of variation in this method. The reproducibility and sensitivity of the soil-jar method using small blocks must be further characterized before it can be accepted as a standard protocol for evaluating preservative-treated wood.

Natureas engineering of wood through genetics, stand conditions, and environment creates wide variability in wood as a material, which in turn introduces difficulties in wood processing and utilization. Manufacturers sometimes find it difficult to consistently process wood into quality products because of its wide range of properties. The primary objective of this study was to investigate the usefulness of a stress wave technique for evaluating wood strength and stiffness of young-growth western hemlock and Sitka spruce in standing trees. A secondary objective was to determine if the...

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...