The mean bending strength of fullsize douglasfir lumber was found to be about 25% lower than ingrade test data of the same species. Structural grades and related allowable properties for visually graded lumber. Wardrop 1951 found an increase in tensile strength with a decrease in microfibril angle for douglas fir and radiata pine. It is an incredibly valuable commercial timber, widely used in construction and building purposes. Douglas fir and western larch western wood products. Impact of tree growth rate on the mechanical properties of douglas fir lumber in belgium jeanmarc henin 1, caroline pollet 2, benoit jourez 1 and jacques hebert 2 1 laboratory of wood technology, public service of wallonia, avenue marechal juin 23, 5030 gembloux, belgium. Douglas fir south select structural 1550 900 165 520 1,200,000 no. The variation in the physical and mechanical properties of ukgrown douglas fir were investigated to determine how strength and stiffness of douglas fir compares to other. Mechanical properties of woods grown in the united states, u. Microfibril angle also influences wood mechanical properties. Douglasfir is technically not a true fir abies genus, but is in its own genus. Earlywood is lighter in weight, softer, and weaker than latewood. An understanding of wood and moisture relationships is of great importance to the manufacture and use of wood products, as is an understanding of the mechanical properties of wood.
Wood coming from plantations or young stands has different properties than wood coming from older, suppressed stands. Ross, supervisory research general engineer 121 contents elastic properties 122. Properties and distortion of douglasfir with comparison. Data is based on small, clear, airdried samples unless specified. These trees bear cones and most of them have needle. Evaluation of the mechanical properties of douglasfir lumber. Wood may show some resin pockets, sometimes of a great dimension. To investigate the quality of douglasfir timber and its biological variation, a variety of sites were sampled in scotland and wales. It was also found that the transverse vibration test is a better nondestructive method of evaluating sawn lumber. Douglas fir s light rosy color is set off by its remarkably straight and handsome grain pattern. However, specific gravity values also reflect the presence of gums, resins, and extractives, which contribute little to mechanical properties.
Because of the greater density of latewood, the proportion of latewood is sometimes used to judge the strength of the wood. Mechanical properties of woodbased composite materials zhiyong cai, supervisory research materials engineer robert j. Properties and distortion of douglasfir with comparison to radiata pine a thesis submitted in partial fulfilment of the requirement for the degree of masters of engineering in chemical and process engineering by eric yunxin wang university of canterbury 2009. Wood moisture and compressive strength red spruce, longleaf pine and douglas fir moisture content and their compressive strength. Chapter 5 mechanical properties of wood modulus of rigidity the modulus of rigidity, also called shear modulus, indicates the resistance to deflection of a member caused by shear stresses. Douglas fir ob outer bark ib inner bark cz cambium zone gi growth increment p pith x wood. This research examined wood properties of smalldiameter plantationgrown douglasfir and western hemlock with the goal of a better understanding of utilization of smalldiameter, fastgrown trees for use in manufacturing. The results of the present study show, that douglas fir mechanical pulp can be used for the production of supercalandered magazine paper but the achieved paper quality is inferior than using norway spruce picea abies mechanical pulp. Acute symptomseffects wood dust may cause mechanical andor chemical irritation of the respiratory system. Ability to predict flexural properties of douglasfir. Wood stiffness is one of the most important properties of lumber and veneer. Mechanical properties of wood based composite materials zhiyong cai, supervisory research materials engineer robert j. Gibson mcilvain has gone through in our decadelong relationship with carrying softwoods, weve come to understand the up sides and down sides of using douglas fir.
The suitability of douglas fir pseudotsuga menziesii in. Douglas fir larch select structural 1,500 1,000 180 625 1,700 1,900,000 wclib. Comparison of stiffness and strength properties of untreated. Most preservative treatments have no significant affect on the mechanical properties of lumber. By any name, douglas fir accounts for about one fifth of north americas total softwood reserves. Comparison of wood quality of douglas fir and spruce from. The mechanical properties presented in this chapter were obtained from tests of pieces of wood termed clear and straight grained because they did not contain characteristics such as knots, cross grain, checks, and splits.
Allowable properties in bending fb, modulus of elasticity moe and compression parallel to grain fe for douglas fir and ponderosa pine logs are given in. Impact of tree growth rate on the mechanical properties of. Structural lumber properties properties of structural lumber timber structural lumber section sizes basic size, area, moments of inertia and section modulus for timber metric units wood moisture and compressive strength red spruce, longleaf pine and douglas fir moisture content and their compressive strength. Potter commissioned the recycled beams from an old barn in eastern wa. Douglas fir can be used both structurally and decoratively. The grain is defined and has a distinctive grain pattern when flat sawn.
Evaluation of the mechanical properties of douglasfir and. The three moduli of rigidity denoted by glr, glt, and grt are the elastic constants in the lr, lt, and rt planes, respectively. Douglasfir the wood database lumber identification. Department of agriculture usda wood handbook strengths previously reported in table 6. Wardrop 1951 found an increase in tensile strength with a decrease in microfibril angle for douglasfir and radiata pine. This method is useful with such species as the southern pines, douglasfir, and the ringporous hardwoods ash, hickory, and oak.
Please note these comparative measures of strength are laboratory values using standardised short lengths of clear timber. It is based on the premise that the mechanical properties of lumber differ from those of clear wood because many. In 1828 seeds were brought to europe by the scottish researcher david douglas. Wood density, modulus of elasticity moe, modulus of rupture mor and impact bending strength were the properties tested that were used for. Wood moisture and compressive strength red spruce, longleaf pine and douglas. In douglas fir, ifju and kennedy 1962 observed a direct correlation between the high microfibril angles associated with juvenile wood and reduced tensile. The douglas fir has been planted in germany and throughout europe since around 1880. Douglasfirlarch select structural 1,500 1,000 180 625 1,700 1,900,000 wclib. This species ranges in colour from light in the sapwood to yellowishreddishbrown in the heartwood. For example evergreens aka conifers are a large majority of the structural lumber.
Wood dust can cause physical obstructions in the nasal passages, resulting in dryness of nose, dry cough, and sneezing. Grading and properties of smalldiameter douglasfir and. A vast wood resource exists in our nations woodframed building infrastructure. Physical and mechanical properties of selected wood species. We studied wood stiffness modulus of elasticity, moe, wood density, microfibril angle, and knots in a 25 yearold wind pollinated progeny test 50 families, 373 trees of coastal douglasfir to understand the potential for genetically improving wood stiffness. Up until the ice age a related sort was widespread throughout europe, but only the american relative survived.
The tree itself grows to be very large, and yields a large amount of usable lumber and veneer for plywood. Physical and mechanical properties are based on mature heartwood. Some property relationships are nearly linear and others exponential. Mechanical properties of canadian coastal douglasfir and. Properties of wood swst international society of wood. Abstract this paper investigates the effect of heat treatment temperature on the stiffness and strength properties of douglas fir pseudotsuga menziesii franco and common alder alnus glutinosa gaertn. Douglas firsouth select structural 1550 900 165 520 1,200,000 no. To investigate the quality of douglas fir timber and its biological variation, a variety of sites were sampled in scotland and wales. Engineering properties of douglasfir lumber reclaimed. Many of the mechanical properties of wood tabulated in this chapter were derived from extensive sampling and analysis. The modulus of elasticity moe and modulus of rupture mor were evaluated for 190 pieces of dimension lumber 2 by 4 lumber, 38 by 89 mm in crosssection produced from larix sibirica trees grown in mongolia. Recent research bodig and arnette, 2000 on fullscale strength testing has been conducted on approximately 100 southern yellow pine piles and 100 douglas fir piles. Douglasfir heartwood is rated to be moderately durable in regard to decay, but is susceptible to insect attack.
Douglas fir is the most widely used wood for building and construction. Mechanical properties of wood charles peterson signature wood. Physical and mechanical properties of selected wood. The value of the 5% tolerance limit of the mor exceeded the characteristic. This method is useful with such species as the southern pines, douglas fir, and the ringporous hardwoods ash, hickory, and oak. The wood is fine to medium texture, straight grain and nonporous. Typically machines well, but has a moderate blunting effect on cutters. Properties and distortion of douglas fir with comparison to radiata pine a thesis submitted in partial fulfilment of the requirement for the degree of masters of engineering in chemical and process engineering by eric yunxin wang university of canterbury 2009. Variation of strength properties in woods used for structural purposes1 by lyman w. Comparison of stiffness and strength properties of untreated and heattreated wood of douglas fir and alder, biores. Properties and distortion of douglasfir with comparison to. A total of 160 pieces of douglasfir sawn lumber pseudotsuga menzresii, wood density in air dried condition ru. The species of tress used for structural lumber are classified as hardwoods and softwoods owing not necessarily to a description of the wood properties.
Comparison of stiffness and strength properties of. Wood, panel and structural timber products mechanical. The wood siding shown in this picture is select tight knot. Mechanical properties of wood forest products laboratory. For machine stress rated lumber bending strength is estimated from modulus of elasticity. Structural properties of laminated douglas fir epoxy. Around 60% of nz grown douglas fir is strong enough for engineering uses, selected using machine stress grading. As a result, wood possesses material properties that may be significantly different from other materials normally encountered in structural design.
Western hemlock tsuga heterophylla general description among the harder, stronger western softwoods, it is marketed and sold separately as well as in the hemfir species combination. Physical and mechanical properties of younggrowth douglas. Wood columns safe loads safe loads for wood columns. Graduate thesis or dissertation stiffness of douglasfir. And, just as shrinking and swelling of wood vary in the radial, tangential, and longitudinal directions, so do various mechanical properties of wood. Douglas fir has a high bending strength, shear strength and stiffness. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, laminatolamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. The country clinic the clinic was built by jerry laverty, and laverty construction, a longtime customer. Thus the mechanical properties of the clear wood may indicate that a species is an excellent wood for boxes. Bending properties of dimension lumber produced from. Evaluation of the mechanical properties of douglasfir and japanese cedar lumber and its structural glulam by nondestructive techniques.
This can mean that the wood can be more easily damaged, so care must be taken in milling, handling, and transporting the lumber. Sometimes it grows over 90 metres high and four and one half metres in diameter. Although severe reactions are quite uncommon, douglas fir has been reported to cause skin irritation, nausea, giddiness, runny nose, along with an increased likelihood of splinters getting infected. The mechanical properties of wood composites depend upon a variety of factors, including wood species, forest management regimes. Wood beams strength of material bending and compression strength of wood species used in beams. Engineering properties of douglasfir lumber reclaimed from deconstructed buildings. Many of the mechanical properties of wood tabulated in this. Wood dust may cause mechanical and possibly chemical irritation of the eyes. On the commercial timberlands of the western region, there are approximately 14 million hectares of douglas fir managed.
In addition, the properties of glulams made from douglasfir lumber, were investigated by measuring the dynamic modulus of elasticity using nondestructive testing. Allowable properties in bending fb, modulus of elasticity moe and compression parallel to grain fe for douglasfir and ponderosa pine logs are given in. The principal growth feature affecting lumber properties are the size and location of. Pdf because stiffness modulus of elasticity moe is important for structural wood products, breeders and silviculturists seek to efficiently. Douglas fir coast type with only threefourths the density of com mercial white oak is about equal to the oak in bending strength and compressive strength, and. Request pdf ability to predict flexural properties of douglasfir crossarms crossarms are heavy timbers used to support electrical lines on utility poles. The mechanical properties presented in this chapter were. Potter mountaintop home a combination of douglas firlarch and western red cedar give this home a timeless western charm.
Coming from north west of america, douglas fir is often used for. Many of the mechanical properties of wood tabulated in this chapter were derived from extensive sampling and analysis procedures. Heartwood is pinkish brown with veins, the large sapwood is yellowish. Like all softwoods, one issue that can be a negative is that the douglas fir wood is, as the softwood name implies, softer than hardwoods. While similar, western larch is slightly darker in color, with the heartwood being a reddish brown and the sapwood a straw brown. Properties of wood there are fewer species of conifers. Grading and properties of smalldiameter douglasfir. The strength properties are derived from clear wood strength of small specimens tested in accordance with astm d 2555 standard test method for establishing clear wood strength values. See the articles wood allergies and toxicity and wood dust safety for more information. In douglasfir, ifju and kennedy 1962 observed a direct correlation between the high microfibril angles associated with juvenile wood and reduced tensile.
Engineering properties of douglasfir lumber reclaimed from. As the buildings in this infrastructure age and are remodeled or removed for redevelopment, the wood framing residing. The results indicated that the dmoev, dmoet and moe values for both douglas fir and japanese cedar lumber showed a decreasing order as follows. Douglasfirplywood eighthedition commercialstandardcs4548 supersedescs4547 effectivedatefornewproductionfromnovemberi,1948 arecordedvoluntarystandard ofthetrade. Mechanical properties of canadian coastal douglasfir and hem. This research examined wood properties of smalldiameter plantationgrown douglas fir and western hemlock with the goal of a better understanding of utilization of smalldiameter, fastgrown trees for use in manufacturing. The average strength of green, clear wood speci mens of coast douglasfir and loblolly pine in compression parallel to grain is approximately 3,784 and 3,511. The variation in the physical and mechanical properties of ukgrown douglasfir were investigated to determine how strength and stiffness of douglasfir compares to other. Evaluation of the mechanical properties of douglasfir. Wood, panel and structural timber products mechanical properties density, fibre stress, compressive strength and modulus of elasticity of clear wood, panel and structural timber products. Wood handbookchapter 4mechanical properties of wood. Comparison of stiffness and strength properties of untreated and heattreated wood of douglas fir and alder this paper investigates the effect of heat treatment temperature on the stiffness and strength properties of douglas fir pseudotsuga menziesii franco and common alder alnus glutinosa gaertn.
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