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THE MECHANICAL PROPERTIES OF WOOD INCLUDING A DISCUSSION OF THE FACTORS AFFECTING THE MECHANICAL PROPERTIES, AND METHODS OF TIMBER TESTING TEXT

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Page 1 8 matches ODUCTS, YALE UNIVERSITY FIRST EDITION FIRST THOUSAND 1914 BY THE SAME AUTHOR Identification of the Economic Woods of the United States. 8vo, vi + 117 pages, 15 figures. Cloth, $1 Page 2 5 matches so would exist just the same. Moreover, it would be found in the latter case that the bow would be much harder to bend than where the piec Page 3 4 matches mate strength in compression parallel to the grain is very nearly the same as the extreme fibre stress at the elastic limit in bending. (See Table V.) In other words, the transverse st Page 4 13 matches VERSE OR BENDING STRENGTH: BEAMS When external forces acting in the same plane are applied at right angles to the axis of a bar so as to cause it to bend, they occasion a shortening Page 5 4 matches nly imposed load is to produce twice the deflection and stress of the same load statically applied. It must be evident, however, that this case has nothing in common with either the or Page 6 3 matches unt that no two woods are alike--in reality no two specimens from the same log are identical. There are certain properties that characterize each species, but they are subject to consi Page 7 9 matches rate of growth on the qualities of chestnut wood is summarized by the same authority as follows: "When the rings are wide, the transition from spring wood to summer wood is gradual, wh Page 8 1 match green to the oven-dry condition, based on the green volume, and s the same based on the oven-dry volume. In tables of specific gravity or density of wood it should always be stated wh Page 9 7 matches , posts, mine props, and sawlogs, is subject to serious damage by the same class of insects as those mentioned above, particularly by the round-headed borers, timber worms, and ambrosi Page 10 5 matches ld be cut into lumber immediately after felling and given exactly the same treatment, for example, kiln-dried, no difference due to the season of cutting would be noted. WATER CONTE Page 11 3 matches k avoided. A comprehensive study of previous investigations along the same or related lines should prove very helpful in outlining the work and preparing the report. (For sample workin Page 12 3 matches data regarding the rate of growth and the proportion of late wood the same procedure is followed as with large beams. _Adjusting specimen in machine_: The beam should be correctly cen Page 13 5 matches y), proportion of late wood, and rate of growth are assumed to be the same as already recorded for the beams. In specimens not so taken, these quantities are determined in the usual wa Page 14 6 matches lizing levers, so arranged that the load at each pinhole would be the same. In all the tests the load was applied vertically by means of the static machine. See Cir. 204, U.S.F.S.: St
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|-----------------+----------+-------+-------+--------+--------+---------+--------+--------+-------+ ------+---------+-------+-------+----------| | | | | | | 1,000 | | | | | | | | | | | | Inches | | | Lbs. | lbs. | Lbs. | Inches | Inches | | | Lbs. | | | Lbs. | | | | | | | | | | | | | | | | | | Longleaf pine | 4 by 5 | 46 | 26.3 | 3,480 | | 4,800 | 4 by 5 | 4 | 22 | 25.1 | 572 | 52 | 20.2 | 984 | | Douglas fir | 6 by 6 | 259 | 20.3 | 3,271 | 1,038 | 4,258 | 4 by 8 | 16 | 44 | 20.8 | 732 | 465 | 22.1 | 822 | | | 2 by 2 | 247 | 18.7 | 3,842 | 1,084 | 5,002 | 4 by 8 | 10 | 32 | 18.1 | 584 | | | | | | | | | | | | 4 by 4 | 8 | 51 | 20.2 | 638 | | | | | | | | | | | | 4 by 4 | 6 | 49 | 24.0 | 613 | | | | | | | | | | | | 4 by 4 | 4 | 29 | 24.8 | 603 | | | | | Shortleaf pine | 6 by 6 | 29 | 15.7 | 4,070 | 1,951 | 6,030 | 8 by 5 | 16 | 4 | 17.8 | 725 | 85 | | 1,135 | | | 2 by 2 | 57 | 14.2 | | | 6,380 | 8 by 5 | 14 | 3 | 16.3 | 757 | | | | | | | | | | | | 8 by 5 | 12 | 5 | 15.1 | 730 | | | | | | | | | | | | 5 by 5 | 8 | 6 | 13.0 | 918 | | | | | | | | | | | | 2 by 2 | 2 | 57 | 13.9 | 926 | | | | | Western larch | 6 by 6 | 112 | 16.0 | | | 5,445 | 8 by 6 | 16 | 17 | 18.8 | 491 | 193 | 15.0 | 905 | | | 4 by 4 | 81 | 14.7 | | | 6,161 | 8 by 6 | 12 | 18 | 17.6 | 526 | | | | | | 2 by 2 | 270 | 14.8 | | | 5,934 | 5 by 4 | 8 | 22 | 13.3 | 735 | | | | | Loblolly pine | 6 by 6 | 23 | | 3,357 | 1,693 | 5,005 | 8 by 5 | 16 | 12 | 19.8 | 602 | 156 | 11.3 | 1,115 | | | 5 by 5 | 10 | 22.4 | 2,217 | 545 | 2,950 | 8 by 5 | 8 | 7 | 22.9 | 679 | | | | | | 4 by 8 | 8 | 19.4 | 3,010 | 633 | 3,920 | 4 by 5 | 8 | 8 | 19.5 | 715 | | | | | | 2 by 2 | 69 | | | | 5,547 | | | | | | | | | | Tamarack | 6 by 7 | 3 | 15.7 | 2,257 | 1,042 | 3,323 | 2 by 2 | 2 | 57 | 16.2 | 697 | 60 | 14.0 | 879 | | | 4 by 7 | 3 | 13.6 | 3,780 | 1,301 | 4,823 | | | | | | | | | | | 4 by 4 | 57 | 14.9 | 3,386 | 1,353 | 4,346 | | | | | | | | | | | 2 by 2 | 66 | 14.6 | | | 4,790 | | | | | | | | | | Western hemlock | 6 by 6 | 102 | 18.6 | 4,840 | 2,140 | 5,814 | 7 by 6 | 15 | 25 | 18.2 | 514 | 131 | 17.7 | 924 | | | 2 by 2 | 463 | 17.0 | 4,560 | 1,923 | 5,403 | 6 by 6 | 6 | 26 | 16.8 | 431 | | | | | | | | | | | | 4 by 4 | 4 | 6 | 15.9 | 488 | | | | | Redwood | 6 by 6 | 18 | 16.9 | | | 4,276 | 8 by 6 | 16 | 5 | 25.4 | 548 | 95 | 12.4 | 671 | | | 2 by 2 | 115 | 14.6 | | | 5,119 | 6 by 6 | 12 | 6 | 14.7 | 610 | | | | | | | | | | | | 7 by 6 | 9 | 5 | 14.8 | 500 | | | | | | | | | | | | 3 by 6 | 14 | 2 | 12.6 | 470 | | | | | | | | | | | | 2 by 6 | 12 | 2 | 16.2 | 498 | | | | | | | | | | | | 2 by 6 | 10 | 4 | 14.3 | 511 | | | | | | | | | | | | 2 by 6 | 8 | 2 | 13.2 | 429 | | | | | | | | | | | | 2 by 2 | 2 | 145 | 13.8 | 564 | | | | | Norway pine | 6 by 7 | 4 | 15.2 | 2,670 | 1,182 | 4,212 | 2 by 2 | 2 | 36 | 10.0 | 924 | 44 | 11.9 | 1,145 | | | 4 by 7 | 2 | 22.2 | 3,275 | 1,724 | 4,575 | | | | | | | | | | | 4 by 4 | 55 | 16.6 | 3,048 | 1,367 | 4,217 | | | | | | | | | | | 2 by 2 | 44 | 11.2 | | | 7,550 | | | | | | | | | |-----------------------------------------------------------------------------------------------------------------------------------------------| | _Note.--Following is an explanation of the abbreviations used in the foregoing tables:_ | | F.S. at E.L. = Fiber stress at elastic limit. | | M. of E. = Modulus of elasticity. | | M. of R. = Modulus of rupture. | | Cr. str. at E.L. = Crushing strength at elastic limit. | | Cr. str. at max. ld. = Crushing strength at maximum load. | |-----------------------------------------------------------------------------------------------------------------------------------------------| |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | TABLE XXII TABLE XXII | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [b]WORKING UNIT-STRESSES FOR STRUCTURAL TIMBER[c] | | EXPRESSED IN POUNDS PER SQUARE INCH | | (From Manual of the American Railway Engineering Assn., 1911, p. 153) | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | NOTE.--The working unit-stresses given in the table are intended for railroad bridges and trestles. For highway bridges and trestles the unit-stresses may be increased | | twenty-five (25) per cent. For buildings and similar structures, in which the timber is protected from the weather and practically free from impact, the unit-stresses may be | | increased fifty (50) per cent. To compute the deflection of a beam under long-continued loading instead of that when the load is first applied, only fifty (50) per cent of the | | corresponding modulus of elasticity given in the table is to be employed. | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | | BENDING | SHEARING | COMPRESSION | | | |---------------------------------+-----------------------------------------+-------------------------------------------------------------------------| Ratio | | | Extreme | Modulus of | Parallel to | Longitudinal | Perpendicular | Parallel to | For | Formulæ for | of | | | fibre | elasticity | the grain | shear in | to the grain | the grain | columns | working stress in | length | | KIND OF | stress | | | beams | | | under 15 | long columns over | of | | TIMBER |--------------------+------------+--------------------+--------------------+--------------------+--------------------| diameters | 15 diameters | stringer | | | Average | Working | | Average | Working | Elastic | Working | Elastic | Working | Average | Working | working | | to | | | ultimate | stress | Average | ultimate | stress | limit | stress | limit | stress | ultimate | stress | stress | | depth | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Douglas fir | 6100 | 1200 | 1,510,000 | 690 | 170 | 270 | 110 | 630 | 310 | 3600 | 1200 | 900 | 1200(1-_l_/60_d_) | 10 | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Longleaf pine | 6500 | 1300 | 1,610,000 | 720 | 180 | 300 | 120 | 520 | 260 | 3800 | 1300 | 980 | 1300(1-_l_/60_d_) | 10 | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Shortleaf pine | 5600 | 1100 | 1,480,000 | 710 | 170 | 330 | 130 | 340 | 170 | 3400 | 1100 | 830 | 1100(1-_l_/60_d_) | 10 | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | White pine | 4400 | 900 | 1,130,000 | 400 | 100 | 180 | 70 | 290 | 150 | 3000 | 1000 | 750 | 1000(1-_l_/60_d_) | 10 | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Spruce | 4800 | 1000 | 1,310,000 | 600 | 150 | 170 | 70 | 370 | 180 | 3200 | 1100 | 830 | 1100(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Norway pine | 4200 | 800 | 1,190,000 | 590[d] | 130 | 250 | 100 | | 150 | 2600[d] | 800 | 600 | 800(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Tamarack | 4600 | 900 | 1,220,000 | 670 | 170 | 260 | 100 | | 220 | 3200[d] | 1000 | 750 | 1000(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Western hemlock | 5800 | 1100 | 1,480,000 | 630 | 160 | 270[d] | 100 | 440 | 220 | 3500 | 1200 | 900 | 1200(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Redwood | 5000 | 900 | 800,000 | 300 | 80 | | | 400 | 150 | 3300 | 900 | 680 | 900(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Bald cypress | 4800 | 900 | 1,150,000 | 500 | 120 | | | 340 | 170 | 3900 | 1100 | 830 | 1100(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | Red cedar | 4200 | 800 | 800,000 | | | | | 470 | 230 | 2800 | 900 | 680 | 900(1-_l_/60_d_) | | |-----------------+----------+---------+------------+----------+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------| | White oak | 5700 | 1100 | 1,150,000 | 840 | 210 | 270 | 110 | 920 | 450 | 3500 | 1300 | 980 | 1300(1-_l_/60_d_) | 12 | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | These unit-stresses are for a green condition of timber and are _l_ = Length in inches. | | to be used without increasing the live load stresses for impact. _d_ = Least side in inches. | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| |[Footnote b: Adopted, Vol. 1909, pp. 537, 564, 609-611.] | |[Footnote c: Green timber in exposed work.] | |[Footnote d: Partially air-dry] | |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| BIBLIOGRAPHY Part I: Some general works on mechanics, materials of construction, and testing of materials. Part II: Publications and articles on the mechanical properties of wood, and timber testing. Part III: Publications of the U.S. Government on the mechanical properties of wood, and timber testing. PART 1. SOME GENERAL WORKS ON MECHANICS, MATERIALS OF CONSTRUCTION, AND TESTING OF MATERIALS ALLAN, WILLIAM: Strength of beams under transverse loads. New York, 1893. ANDERSON, SIR JOHN: The strength of materials and structures. London, 1902. BARLOW, PETER: Strength of materials, 1st ed. 1817; rev. 1867. BURR, WILLIAM H.: The elasticity and resistance of the materials of engineering. New York, 1911. CHURCH, IRVING P.: Mechanics of engineering. New York, 1911. HATFIELD, R.G.: Theory of transverse strain. 1877. HATT, W.K., and SCOFIELD, H.H.: Laboratory manual of testing materials. New York, 1913. JAMESON, J.M.: Exercises in mechanics. (Wiley technical series.) New York, 1913. JAMIESON, ANDREW: Strength of materials. (Applied mechanics and mechanical engineering, Vol. II.) London, 1911. JOHNSON, J.B.: The materials of construction. New York, 1910. KENT, WILLIAM: The strength of materials. New York, 1890. KOTTCAMP, J.P.: Exercises for the applied mechanics laboratory. (Wiley technical series.) New York, 1913. LANZA, GAETANO: Applied mechanics. New York, 1901. MERRIMAN, MANSFIELD: Mechanics of materials. New York, 1912. MURDOCK, H.E.: Strength of materials. New York, 1911. RANKINE, WILLIAM J.M.: A manual of applied mechanics. London, 1901. THIL, A.: Conclusion de l'étude présentée à la Commission des méthodes d'essai des matériaux de construction. Paris, 1900. THURSTON, ROBERT H.: A treatise on non-metallic materials of engineering: stone, timber, fuel, lubricants, etc. (Materials of engineering, Part I.) New York, 1899. UNWIN, WILLIAM C.: The testing of materials of construction. London, 1899. WATERBURY, L.A.: Laboratory manual for testing materials of construction. New York, 1912. WOOD, DEVOLSON: A treatise on the resistance of materials. New York, 1897. PART II. PUBLICATIONS AND ARTICLES ON THE MECHANICAL PROPERTIES OF WOOD, AND TIMBER TESTING ABBOT, ARTHUR V.: Testing machines, their history, construction and use. Van Nostrand's Eng. Mag., Vol. XXX, 1884, pp. 204-214; 325-344; 382-397; 477-490. ADAMS, E.E.: Tests to determine the strength of bolted timber joints. Cal. Jour, of Technology, Sept., 1904. ALVAREZ, ARTHUR C.: The strength of long seasoned Douglas fir and redwood. Univ. of Cal. Pub. in Eng., Vol. I, No. 2, Berkeley, 1913, pp. 11-20. BARLOW, PETER: An essay on the strength and stress of timber. London, 1817; 3d ed., 1826. ----: Experiments on the strength of different kinds of wood made in the carriage department, Royal Arsenal, Woolwich. Jour. Franklin Inst., Vol. X, 1832, pp. 49-52. Reprinted from Philosophical Mag. and Annals of Philos., No. 63, Mch., 1832. BATES, ONWARD: Pine stringers and floorbeams for bridges. Trans. Am. Soc. C.E., Vol. XXIII. BAUSCHINGER, JOHANN: Untersuchungen über die Elasticität und Festigkeit von Fichten- und Kiefernbauhölzern. Mitt. a. d. mech.-tech. Laboratorium d. k. techn. Hochschule in München, 9. Hft., München, 1883. ----: Verhandlungen der Münchener Conferenz und der von ihr
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