Effect of Incising and Preservative Treatment on Shear Strength of Nominal 2-Inch Lumber


  • Jeffrey J. Morrell
  • Rakesh Gupta
  • Jerrold E. Winandy
  • Djoko S. Riyanto


Incising, preservative treatment, shear strength, MSR lumber, grade, torsion


This study evaluated the effects of pretreatment incising of dry lumber and preservative treatment on the shear strength of 1980 pieces of 2 X 4 dimension lumber (nominal 50 mm X 100 mm X 3.6 m long). Three species groups (Douglas-fir, Hem-Fir, adn Spruce-Pine-Fir-South) and two commercially produced machine-stress-rated grades per species group were tested in torsion to determine their shear strength. Incising and preservative treatment produced significant reductions in the average shear strength of Douglas-fir, Hem-Fir, and Spruce-Pine-Fir-South dimension lumber. These effects need to be addressed through the development of more appropriate design values for uses of preservativetreated wood of these species when shear is a governing factor. An adjustment factor of 0.70 is proposed for incised and preservative-treated nominal 2-inch lumber.


American Forest and Paper Association (AFPA). 1997. National design specification for wood construction. ANSI/AFPA NDS-1997. AFPA, Washington, DC. 174 pp.nAmerican Society for Testing and Maretrials (ASTM). 1997. Standard methods of static test of lumber in structural size. ASTM D 198-94. Pages 57-75 in Annual Book of Standards, vol. 4.10. West Conshohocken, PA.nAmerican Wood-Preservers' Association (AWPA). 1996. Standard C2-lumber, timber, bridge ties and mine ties-preservative treatment by pressure processes. Pages 27-40 in AWPA Book of Standards. Woodstock. MD.nAnderson, M., J. J. Morrell, and J. E. Winandy. 1997. Effect of incising depth and density on treatability of Douglas-fir, Hem-Fir, and Spruce-Pine-Fir lumber with ACZA, CCA or ACQ. IRG/WP/97-40193. International Research Group on Wood Preservation. Stockholm, Sweden. 8 pp.nBarnes, H. M., D. E. Lyon, A. R. Zahora, and F. Muisu. 1993. Strength properties of ACQ-treated southern pine lumber Proc. Am. Wood-Preserv. Assoc. 89:51-59.nBorest, A. R., R. J. Schmidt, and O. M. Sidebottom. 1993. Advanced mechanics of materiaqls, 5th ed. John Wiley & Sons, Inc., New York, NY. 811 pp.nBrown, L. S., D. A. DeVisser, R. S. Tuvey, and A. K. Rozek. 1997. Mechanically graded lumber: A grading agency perspective. Wood Design Focus 8(2):3-7.nCanadian Standards Association (CSA). 1989. Standard 086.1M: Code on engineerin design in wood. Rexadale, Ontario, Canada.nHarkom, J. F., and H. G. Rochester. 1930. Strength tests of creosoted Douglas-fir beams. Can. Dep. Interior For. Serv. Circ. 29. Ottawa, Canada.nHeck, L. 1997. Evaluation of the torsion test for determining the shear strength of structural lumber. M.S. thesis, Departement of Forest Products, Oregon State University, Corvallis, OR.nLam, F., and P. I. Morris. 1991. Effect of double-density incising on bonding strength. Forest Prod. J. 41(6):43-47.nLebow, S. T., and J. J. Morrell. 1993. A comparison between high and conventional incision densities for improving preservative treatment of Douglas-fir heartwood lumber. IRG/WP/93-4009. International Research Group on Wood Preservation, Stockholm, Sweden. 8 pp.nMorrell, J. J., and J. E. Winandy. 1987. Incising practices used to improve preservative treatment in western species: A preliminary survey. Proc. Am. Wood-Preserv. Assoc. 83:400-404.nMorris, P. I., J. J. Morrell, and J. N. R. Ruddick. 1994. A review of incising as a means of improving treatment of sawnwood. IRG/WP/93-40019. International Research Group on Wood Preservation, Stockholm, Sweden. 24 pp.nPerrin, P. 1978. Review of incising and its effect on strength and preservative treatment of wood. Forest Prod. J. 28(9):27-33.nRammer, D. R., L. A. Soltis, and P. K. Lebow. 1996. Experimental shear strength of unchecked solid-sawn Douglas-fir. USDA For. Serv. Res. Pap. FPL-RP-553. Forest Prod. Lab., Madison, WI. 33 pp.nRawson, R. H. 1927. A study of the creosote treatment of 6-inch by 12-inch Douglas-fir beams, covering boiling-under-vacuum-pressure process and influence of incising. Proc. Am. Wood-Preserv. Assoc. 23:203-213.nRiyanto, D. S., and R. Gupta. 1998. A comparison of test methods for evaluating shear strength of structural lumber. Forest Prod. J. (in press).nSchrader, O. H., Jr. 1945. Tests of creosoted laminated stringers. Eng. News Record 135:650-653.nSmith, S. M., and J. J. Morrell. 1991. Measuring distribution of chromated copper arsenate around incisions in Douglas-fir heartwood by direct scan x-ray techniques. Wood Prot. 1(1):31-37.nSoltis, L. A., and D. R. Rammer. 1994. Experimental shear strength of glue-laminated beams. USDA Forest Serv. Res. Pap. FPL-RP-527. Forest Prod. Lab., Madison, WI.nWinandy, J. E. 1995. Effects of waterborne preservative treatmetn on mechanical properties: A review. Proc. Am. Wood-Preserv. Assoc. 91:17-33.nWinandy, J. E., and S. Lebow. 1997. Effects of ammoniacal copper citrate preservative treatment and redrying on bending properties of two grades of southern pine 2 by 4 lumber. Forest Prod. J. 47(7/8):91-98.nWinandy, J. E., and J. J. Morrell. 1998. Effects of incising on lumber strength and stiffness: Relationships between incision density and depth, species and MSR-grade. Wood Fiber Sci. 30(2):185-197.nWinandy, J. E., J. J. Morrell, and S. T. Lebow. 1995. Review of effects of incising on treatability and strength. Pages 65-69 in Proc. Wood Preservation in the 90s and Beyond. Forest Products Society, Madison, WI.n






Research Contributions