Tests on the Physical Properties of Timber

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Page 534 - White Pine, Red Pine, Spruce Pine, Bald Cypress, White Cedar, Douglas Spruce, White Oak, Overcup Oak, Post Oak, Cow Oak, Red Oak, Texan Oak, Yellow Oak, Water Oak, Willow Oak, Spanish Oak, Shagbark Hickory, Mockernut Hickory, Water Hickory, Bitternut Hickory, Nutmeg Hickory, Pecan Hickory, Pignut Hickory, White Elm, Cedar Elm, White Ash, Green Ash, and Sweet Gum.
Page 535 - ... with results which it is safe to use in practical cases where fullsize pieces are used. Inasmuch as these small pieces are necessarily much more perfect (otherwise they would not be considered fit for testing), having less defects, such as knots, shakes, etc.. than the full-size pieces, they have also a far greater homogeneity. They also season much more quickly and uniformly than full-size pieces. In making this statement. I am only urging the importance of adopting in the experimental work...
Page 535 - time tests" were made on spruce and Yellow Pine; the weights were allowed to remain on the beams for periods of from one month to over a year. From these time tests Professor Lanza draws the conclusion that " the deflection of a timber beam under a long-continued application of the load may be two or more times that assumed when the load was first applied.
Page 537 - Series III, is one which will require careful study. It has been found in former tests that timber when moist may be 50 per cent weaker than when comparatively dry. All test material must therefore be reduced to a common degree of moisture contents, and in the case of many species the volatile oils must also be taken into account. For this purpose a method is under consideration which reduces the disks (to be tested for moisture contents) to shavings. These shavings are placed in an iron retort surrounded...
Page 535 - Inasmuch as these small pieces are necessarily much more perfect (otherwise they would not be considered fit for testing), having less defects, such as knots, shakes, etc., than the full-size pieces, they have also a far greater homogeneity. They also season much more quickly and uniformly than full-size pieces. In making this statement, I am only urging the importance of adopting in the experimental work the same principle that the physicist recognizes in all his work, viz, that he must not apply...
Page 533 - ... near approach to the truth only: (1) Stems of spruce or pine which are of the same age at equal diameters, and in which the rate of growth is about equal, have the same mechanical properties (when reduced to the same moisture contents), irrespective of local conditions of growth. (2) Stems of spruce or pine which are felled in winter have, when tested two or three months after the felling, about 2~> per cent greater strength than those felled in summer, other conditions being the same.
Page 533 - ... unsatisfactory. In 1848 Chevandier and Wertheim published the results of tests they had made on timber of the Vosges Mountains. This was the first case in which a fairly good history and description of the test material was given, and their results are even now in use. Most of the modern work in timber testing is founded on that of Dr. II.
Page 536 - The effect of moisture and volatile oils on the strength of timber," Series III, is one which will require careful study. It has been found in former tests that timber when moist may be 50 per cent weaker than when comparatively dry. All test material must therefore be reduced to a common degree of moisture contents, and in the case of many species the volatile oils must also...
Page 535 - TECHNOLOGY. Prof. G. Lanza, at the Massachusetts Institute of Technology, has done a considerable amount of timber-test work, and in 1804 published his results in Applied Mechanics. Tests were made on a limited number of Yellow Pine and White Oak columns and spruce pillars and compression tests on White Pine and Yellow Pine posts. Transverse tests to determine the breaking load, modulus of rupture, and modulus of elasticity were made on beams of the following species: Yellow Pine, 52 beams; White...
Page 534 - Of these, the greatest number of tests were made on Bald Cypress, White Oak, Cow Oak, Overcup Oak, and Spanish Oak. Dr. BE Fernow, under whose direction the tests were made, makes the following statement in regard to the work: As will be observed, some species, like the Southern pines, have been more fully investigated, and the results on these (published in Circular 12; Division of Forestry) may be taken as authoritative. With those species of which only a small number of trees have been tested...

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