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The designated fiber stress values published in the American National Standards Institute Standard for Poles, ANSI 05.1, no longer reflect the state of the knowledge. These values are based on a combination of test data from small clear wood samples and small poles (

To satisfy the increasing demand for forest products, much of the future timber supply will be 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 than that of current harvests. In anticipation of this resource, definitive information is needed on the influence of juvenile wood on lumber properties so that grading rules and the associated allowable design stresses can be modified as needed. This document reports the results of an extensive review of the literature on...

Preservative-treated wood is often used for construction of highway and foot bridges, wetland boardwalks, and other structures in or over water or sensitive environments. In these applications it is important that release of preservative from the wood into the environment is minimized. This publication addresses this concern by describing the various types of pressure-treated wood, reviewing recent research on the environmental impacts of pressure-treated wood, and discussing methods of minimizing potential environmental impacts. Recent research indicates that wood treated with these...

To enhance long-term timber bridge performance, timber material must be protected from moisture. Wearing surfaces made of asphalt pavement with and without a waterproof membrane have been used to provide protection from moisture on timber decks. This type of wearing surface also protects the deck from other damage while providing a smooth, skid-resistant surface. However, the long-term performance of timber bridges has often not been satisfactory as a result of cracking of the wearing surface or separation of the asphalt or membrane from the deck. Cracking or separation allows moisture...

In this report, we assess the unmitigated pest risk potential of importing Eucalyptus logs and chips from South America into the United States. To do this, we estimated the likelihood and consequences of introducing representative insects and pathogens of concern. Nineteen individual pest risk assessments were prepared, eleven dealing with insects and eight with pathogens. The selected organisms were representative examples of insects and pathogens found on the foliage, on the bark, in the bark, and in the wood of Eucalyptus spp. Among the insects and pathogens assessed, eight were rated a...

These standardized bridge plans are for superstructures consisting of treated timber. Seven superstructure types are includes: five longitudinal and two transverse deck systems. Both HS520 and HS25 loadings are included, along with L/360 and L/500 deflection criteria.

ASTM D1990, “Establishing Allowable Properties for Visually Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens,” is the consensus standard used to make submissions of allowable properties for many U.S., Canadian, and foreign species to the Board of Review of the American Lumber Standards Committee. Recently, it has become apparent how difficult it is to perform the calculations for such a submission. Some calculations are clearly specified in the standard; in some cases the standard merely indicates a need to make an adjustment but does not specify how to do so. This report...

Will the National Forests become a more reliable supplier of timber again in conjunction with the National Fire Plan? The National Forests represent a major potential source of wood fiber in the West. They occupy 48% of the commercial forestland, hold 63% of the region?s softwood growing stock, and contribute 48% of its net annual growth. But in California, Idaho, Montana, Oregon, and Washington, timber sales have declined from an average of 8 billion board feet per year during 1960-1 990 to about 1.5 billion board feet since. The new millennium saw the lowest volumes offered since the...

Stress-wave-based nondestructive evaluation methods were used to evaluate the potential quality and modulus of elasticity (MOE) of wood from creosote-treated Douglas-fir and southern pine piles removed from service. Stress-wave measurements were conducted on each pile section. Stress-wave propagation speeds were obtained to estimate the MOE of the wood. Tests were then conducted on octagonal cants, boards, and small clear specimens obtained from piles and cants. Regression analyses gave a reasonably useful correlation between the stress-wave-based MOE of piles and cants and the correspondin...

Trends in the stability of ¥á and ©¬-Keggin heteropolytungstates of the second-row main-group heteroatoms Al(III), Si(IV), and P(V) are elaborated by data that establish the roles of kinetic and thermodynamic control in the formation and isomerization of Keggin tungstoaluminates. Slow, room-temperature co-condensation of Al(III)and W(VI) (2:11 molar ratio) in water gives a pH 7 solution containing ©¬1 and ©¬2 isomers of [Al(AlOH2)W11O39]6-(©¬1- and ©¬2=1). Partial equilibration of this kinetic product mixture by gentle heating (2 h at 100¡ÆC) or, alternatively, co-condensation of Al(III)...