Effects of Strand Geometry on Selected Properties of Long-Stand Structural Composite Lumber Made from Northeastern Hardwoods

Structural composite lumber (SCL) products often possess significantly higher design values than the top grades of solid lumber, making it a popular choice for both residential and commercial applications. The enhanced mechanical properties of SCL are mainly due to defect randomization and densification of the wood fiber, both largely functions of the size, shape and composition (species) of the wood element. Traditionally, SCL manufacturers have used thin, rectangular elements produced from either moderate density softwoods or low density hardwoods. Higher density hardwood species have been avoided, as they require higher pressures to adequately densify and consolidate the wood furnish. These higher pressures can lead to increased manufacturing costs, damage to the wood fiber and/or a product that is too dense, making it heavy and unreceptive to common mechanical fastening techniques. In the northeastern United States high density, diffuse-porous hardwoods (such as maple, beech and birch) are abundant. Use of these species as primary furnish for a SCL product may allow for a competitive advantage in terms of resource cost against products that rely on veneer grade logs. Proximity to this abundant and relatively inexpensive resource may facilitate entry of SCL production facilities in the northeastern United States, where currently none exist. However, modifications to current strand sizes, geometries or production techniques will likely be required to allow for use of these species. A new SCL product concept has been invented allowing for use of these high density hardwoods. The product, referred to as long-strand structural composite lumber (LSSCL), uses strands of significantly larger cross sectional areas and volumes than existing SCL products. In spite of the large strand size, satisfactory consolidation is achieved without excessive densification of the wood fiber through use of a symmetrical strand geometric cross-section. LSSCL density is similar to that of existing SCL products, but is due mainly to the inherent density of the species, rather than through densification. An experiment was designed and conducted producing LSSCL from both large (7/16”) and small (1/4”) strands, of both square and triangular geometric cross sections. Testing results indicate that the large, triangular strands produce LSSCL beams with projected design values of: Modulus of elasticity (MOEapp) – 1,750,000 psi; Allowable bending stress (Fb) – 2750 psi; Allowable shear stress (Fv) – 260 psi. Several modifications are recommended which may lead to improvement of these values, likely allowing for competition against existing SCL products.

Stand Structure Governs the Crown Collisions of Lodgepole Pine

We investigated tree sway and crown collision behavior of even-aged lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) stands of different structure in Alberta, Canada, to examine how these factors might affect loss of leaf area as stands mature. The Two Creeks stand (TC) had high density and slender trees, while the Chickadee stand (CH) had stout trees. The TC stand was then thinned (TCT) to reduce the stand density. For each stand, simultaneous tree sways of a group of 10 trees were monitored with biaxial clinometers during wind speed of 5 m/s (canopy top). Crown collisions were reconstructed by combining sway displacement of individual trees with their respective crown dimensions. Comparing the sway statistics between stands with contrasting mean bole slenderness (TC and CH) indicated that more slender trees have greater sway displacements, faster sway speeds, and a greater depth of collision. Disturbance by thinning increased sway displacements, sway speeds, and depth of collisions at TCT. Tree sway patterns were circular in shape and not aligned with wind direction, but patterns were elongated after thinning. This demonstrates the high frequency of crown collision experienced by stands with slender trees and supports the notion that crown collisions result in empty space between crowns of trees.

Der Stand des Minderheitenrechtes

Rudolf Levy

Der gegenwärtige Stand der jüdischen Bibliographie

Aaron Freimann

Stand und Bewegung der jüdischen Bevölkerung im Grossherzogtum Hessen während des 19. Jahrhunderts

Knöpfel

Der Stand der jüdischen Bevölkerung in Bayern am 1. Dezember 1905 : im Auftrage des Münchener Vereins f. d. Statistik der Juden

Rudolf Wassermann

Der Stand der Statistik der Juden

A. R.

Die neuesten Angaben über den Stand der jüdischen Bevölkerung in Russisch-Polen

Salomon Margolin

Stand der jüdischen Bevölkerung in Deutschland auf Grund der Volkszählung v. 1. Dez. 1910 : Preußen

Jakob Segall

Stand der jüdischen Bevölkerung in Deutschland auf Grund der Volkszählung v. 1. Dez. 1910 : Bayern

Jakob Segall

Stand der jüdischen Bevölkerung in Deutschland auf Grund der Volkszählung vom 1. Dezember 1910 : (III. Elsass-Lothringen)

Jakob Segall

Über den gegenwärtigen Stand der Torfmoosforschung in Oberbayern

von Dr. Hermann Paul

Der Stand unserer Kenntnis von der Tierwelt des Kreises Berent

Von Dr. med. P. Speiser

Ueber den derzeitigen Stand der gesetzlichen Schutzbewegung zu Gunsten der Alpenflora unter besonderer Berücksichtigung der Tätigkeit des "Vereins zum Schutze der Alpenpflanzen" : Nachtrag V.

von C. Schmolz