Treesearch

To establish the effect of using modulus elasticity in addition to visual grade as criteria for the positioning of laminations in laminated beams, an experimental study on southern pine members was conducted. The beams were manufactured in accordance with current specifications for glued-laminated southern pine timber, except that (a) minimum-quality tension laminations meeting AITC 301-67were used and (b) restrictions were placed on the modulus of elasticity of all laminations. Current specifications require that boards lie positioned in laminated members on the basis of their visual...

This note presents theoretical analyses for determination of dimensions of structural sandwich of minimum weight that will have certain stiffness and load-carrying capabilities. Included is a brief discussion of the resultant minimum weight configurations.

Although many outlets are available for the utilization of wood fines, economical disposal of sawdust, shavings, and waste chips remains a problem of growing concern to the wood industry. This report summarizes current uses for wood residues and provides sources of further information on available outlets, processing methods, and economic considerations.

A relatively simple test procedure was developed to evaluate the behavior of various adhesives near fire-exposed surfaces in laminated constructions. A number of sections cut from laminated blocks were exposed to fire on one surface. After this exposure, the sections were transversely cut, and the gluelines were examined for separation depth. In addition, the cool specimens were broken along the glue joints so as to be able to determine the residual bonded area. An equation incorporating both the separation depth and the residual bonded area at the joints was utilized to obtain a bdegradati...

This analysis of a mass increment core sampling of eight coniferous species of Maine characterizes specific gravity for each of the species. No clear-cut relationships of specific gravity to forest type, stand density class, height class, or tree diameter at breast height were found. Included in the data are the species average specific gravity and the range. These data can be used in the assembly of working equations for weight scaling, pulp yield estimation, and strength evaluation.

Successive stages of decay in the sapwood of sweetgum (Liquidambar styraciflua L.), a hardwood, and of southern pine (Pinus sp.), a softwood, were observed microscopically. The white-rot fungus. Polyporus versicolor L., and the brown-rot fungus, Poria monticola Murr., were the fungi used or the observations, light microscopy, plus the techniques of polarization and ultraviolet-absorption microscopy, was used on sections 4 microns thick cut from celloidin-embedded specimens. For both fungi, hyphae were widespread in the early stages of decay in both types of wood. The hyphae of the white...

Gives the general resistance to decay of a number of native wood species grown in the United States, and some factors affecting decay resistance.

Historically, log quality has been evaluated by log grading systems based on judgment and experience. The hardwood log grades for standard lumber, as developed by the Forest Products Laboratory, are based on an analysis of the relationship between log characteristics and end product yield.This system enables foresters, timber sellers, and timber buyers to separate, from woods-run hardwood logs, those logs suitable for manufacture into factory grade lumber and to rank the logs into categories of high-, medium-, and low-quality yields.The yield tables provide the information necessary for...

This paper discusses the assumptions used in the statistical theory of strength, shows the application of the theory to wood bending members, and gives a comparison between theory and actual data for wood beams.

Requests are frequently received by the Forest Products Laboratory to examine warped plywood, veneered table tops, or similar products, to explain the cause of the warping, and if possible to suggest measures to remedy the difficulty.