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

|-----------------+----------+-------+-------+--------+--------+---------+--------+--------+-------+ ------+---------+-------+-------+----------| | | | | | | 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