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The mechanical properties presented in this chapter were obtained from tests of small pieces of wood termed “clear” and “straight grained” because they did not contain characteristics such as knots, cross grain, checks, and splits. These test pieces did have anatomical characteristics such as growth rings that occurred in consistent patterns within each piece. Clear wood specimens are usually considered “homogeneous” in wood mechanics. Many of the mechanical properties of wood tabulated in this chapter were derived from extensive sampling and analysis procedures. These properties are...

The versatility of wood is demonstrated by a wide variety of products. This variety is a result of a spectrum of desirable physical characteristics or properties among the many species of wood. In many cases, more than one property of wood is important to the end product. For example, to select a wood species for a product, the value of appearance- type properties, such as texture, grain pattern, or color, may be evaluated against the influence of characteristics such as machinability, dimensional stability, or decay resistance. Wood exchanges moisture with air; the amount and direction of...

Under proper conditions, wood will give centuries of service. However, if conditions exist that permit the development of wood-degrading organisms, protection must be provided during processing, merchandising, and use. The principal organisms that can degrade wood are fungi, insects, bacteria, and marine borers. Molds, most sapwood stains, and decay are caused by fungi, which are microscopic, thread-like microorganisms that must have organic material to live. For some of them, wood offers the required food supply. The growth of fungi depends on suitably mild temperatures, moisture, and air...

In a broad sense, commercial lumber is any lumber that is bought or sold in the normal channels of commerce. Commercial lumber may be found in a variety of forms, species, and types, and in various commercial establishments, both wholesale and retail. Most commercial lumber is graded by standardized rules that make purchasing more or less uniform throughout the country. When sawn, a log yields lumber of varying quality. To enable users to buy the quality that best suits their purposes, lumber is graded into use categories, each having an appropriate range in quality. Generally, the grade...

Since the summer of 1996, a project has been underway at the University of Wisconsin-Madison,Dept. of Plant Pathology, to determine how different forest management regimes can affect the diversity of fungi found in northern hardwood forests. This report is an introduction to this project's goals, objectives and methods. A particular group of fungi, the wood-inhabiting polyporoid and corticioid fungi (commonly known as the polypores and the crust fungi), was chosen for this project. To date, fruiting bodies have been sampled for two years in forest stands in northern Wisconsin and the...

To date, there is no standard method for evaluating the structural integrity of wood floor systems using nondestructive techniques. Current methods of examination and assessment are often subjective and therefore tend to yield imprecise or variable results. For this reason, estimates of allowable wood floor loads are often conservative. The assignment of conservatively low, allowable floor loads often means that the continued use, or adaptive use, of an historic building is uneconomical, resulting in demolition of inappropriate rehabilitation. Successful completion of this project will...

Preservative-treated wood products are important construction materials. Preservative-treated wood pilings, after removal from service, constitute a major disposal problem for managers of waterfront facilities. For example, approximately 7,000 to 8,000 tons of mechanically or biologically deteriorated wood pilings are currently removed from U.S. naval facilities annually. While many of these poles are no longer useful for piles, a considerable amount of the wood in them may be used for other exterior applications. The key to using the sound wood in these poles is the development of a...

The continuous lumber tester (CLT) is the most widely used grading machine in the world. With the CLT, the flatwise bending stiffness of lumber is measured as it passes through the machine. The modulus of elasticity (MOE) is calculated from the force required to bend the lumber to a fixed deflection of 7.94 mm (5/16 in.), and this MOE is used in assigning a machine grade. Quality control testing is also required to assure proper grade assignment. Usually, quality control is based on tests of bending stiffness and strength. In commercial practice, the lumber passing through the CLT may...

This study sought to determine the effect of fixation time and temperature on the release of copper, chromium and arsenic from treated marine piles immersed in seawater under "worst case" conditions. Sections of piles were CCA-C treated to a target retention of 2.5 lbs/ft3) (40 kg/m3) and then allowed to Condition at 36°F (2°C) for either 3, 7 or 20 days. As a control, one set of "wel1 fixed'' pile sections was conditioned at 80°F (27°C) for 20 days prior to leaching. Following the designated fixation period, the sections were leached in seawater maintained at 36 °F (2 °C). Fixation...

Longitudinal stress wave nondestructive evaluation (NDE) techniques have been used in a variety of applications in the forest products industry. Recently, it has been shown that they can significantly aid in the assessment of log quality, particularly when they are used to predict performance of structural lumber obtained from a log. The purpose of the research described in this report was to investigate the use of stress-wave- based techniques for assessing the potential quality of veneer obtained from logs. Sixty-two ponderosa pine veneer blocks from 22 tree-length logs were nondestructiv...