Treesearch

The National Forest Products Association (NFPA), upon the recommendation of its Technical Advisory Committee and its Special Advisory Committee, has adopted the author’s design equation for compression members under combined bending and compression for the next edition of the National Design Specification (NDS). Included in the formulation are new slenderness reduction factors (now called the “column stabilityfactor CP” and the “beam stability factor C>sub>L”). This paper compares the new and old equations and indicates their effect on design.

In many applications of Monte Carlo simulation in forestry or forest products, it may be known that some variables are correlated. However, for simplicity, in most simulations it has been assumed that random variables are independently distributed. This report describes an alternative Monte Carlo simulation technique for subjectively assesed multivariate normal distributions. The method requires subjective estimates of the 99-percent confidence interval for the expected value of each random variable and of the partial correlations among the variables. The technique can be used to generate...

As part of a fire growth program to develop and validate a compartment fire model, several bench-scale and full-scale tests were conducted. This paper reports the full-scale wall and corner test results of step 2 of this study. A room fire test following the ASTM proposed standard specifications was used for these full-scale tests. In step 1, we investigated the combination of factors for evaluating wood products in wall and corner fire tests. They were the position of the ignition sources power output from the source, and combination of lining materials. We concluded from the sensitivity...

A cost function approach was examined for using the concept of duality between production and input factor demands. A translog cost function was used to represent residential construction costs and derived conditional factor demand equations. Alternative models were derived from the translog cost function by imposing parameter restrictions.

This report documents a package of computer programs called VENVAL. These programs prepare plywood mill data for a linear programming (LP) model that, in turn, calculates the optimum mix of products to make, given a set of technologies and market prices. (The software to solve a linear program is not provided and must be obtained separately.) Linear programming finds the best solutions for a given set of circumstances. This paper illustrates and describes the software programs of VENVAL and its use in LP for softwood plywood mill operations.

In 1985, the U.S. Congress mandated a program commonly called the Caribbean Initiative. To fulfill their portion of this Initiative, the USDA Forest Service developed a “Program for Tropical Forestry in Latin America and the Caribbean.” This document is part of the Forest Service program, and it was funded by the legislation for the Caribbean Initiative. This document is based on an extensive survey (nearly 3,000 documents) of the world literature pertaining to Latin American woods and their use. It contains a discussion of the resource, the literature, the state of the knowledge, and the...

Wood continues to play an important role as a structural material in today’s high-tech society. As lumber and in reconstituted products, wood is commonly used for house siding, trim, decks, fences, and countless other exterior and interior applications. When wood is exposed to the elements, particularly sunlight and moisture, special precautions must be taken in structural design as well as in the selection and application of the finish. This is especially true in the South, where excessive moisture can quickly damage a structure and erode the finish. This report describes the characteristi...

Many tropical species are underutilized because of their varied and frequently unknown drying properties. When handling a large number of species, harvesting and processing the species individually is impractical, and grouping species by similar drying properties is difficult. This report examines the relationship between green moisture content and specific gravity of tropical species, using data gathered from the world literature. The report shows how these data, converted to green weight density, can be used to estimate drying times and thus to group tropical species by similar estimated...

Wood is a porous, permeable, hygroscopic, orthotropic, biological composite material of extreme chemical diversity and physical intricacy. Table 1.1 provides an overview of the may variables, including wood variables, that bear on the bonding and performance of wood in wood joints and wood-based materials. Of particular note is the fact that wood properties vary between species, between trees within a species, and even within a tree. Variability within a single species alone is enough to significantly challenge an adhesive to perform consistently and satisfactorily. In this chapter, we...

Literature dealing with the effect of excessive drying (overdrying) on wood surface inactivation to bonding is reviewed in two parts and critically evaluated, primarily for phenolic adhesives. Part 1 of the review, published earlier, covers physical mechanisms that could contribute to surface inactivation. The principal physical mechanism is the migration to the surface ofextractives that decrease wettability. Pan II of the review considers mechanisms involving chemical reactions: reduction of wood surface strength, oxidation and pyrolysis of wood bonding sites, and chemical interference...