Tension-Perpendicular-to-Glueline Strength of Douglas-Fir Lumber Laminated at High Temperatures


  • J. C. Bohlen


<i>Pseudotsuga menziesii</i>, glued-laminated beams, tensile strength, glue-line durability, phenol resorcinol


Preheated Douglas-fir was laminated with high-temperature phenol-resorcinol and ureamelamine adhesives employing the residual heat in the wood to accelerate the cure. Tension specimens were prepared from these laminations, as well as from conventionally glued-laminated wood and wood that was not glued. Prior to testing, one-half of the specimens were conditioned at room temperature and the other half received a 24-hr cold water soak. All glued specimens were weaker than the solid-wood specimens. In the dry condition, the heat-treated material was comparable in strength to conventionally glued specimens. When tested wet (an estimate of durability), the strength reduction of the heat-treated wood glued with phenol-resorcinol ranged from 42% for treatments at 380 F (193 C) to 56% for treatments at 500 F (260 C). In contrast, the conventionally glued material was reduced in strength by only 8%, which compares with published values for solid wood. Thus, the heat-treated wood formed gluelines that are presumably less durable in tension than the conventionally glued-laminated wood.


American Society Testing Material. 1971. ASTM Stand. D-143, Philadelphia, Pa. Part 16.nBohlen, J. C. 1971. Shear strength of Douglas-fir lumber laminated at high temperatures. Can. For. Ser., Western For. Prod. Lab., Inform. Rep. VP-X-89, Vancouver, B.C.nBohlen, J. C. 1972. Shear strength of high-temperature heat-treated Douglas-fir lumber laminated with phenol-resorcinol adhesives. For. Prod. J. 22(12):17-24.nCanadian Standards Association. 1960. Specifications for urea resin adhesives for wood. CSA Stand. 0112.5—1960, Rexdale, Ont.nCanadian Standards Association. 1965. Qualification code for manufacturers of structural glued-laminated timber. CSA Stand. 0177—1965, Rexdale, Ont.nCoker, E. C., and C. P. Coleman. 1930. Cleavage tests of timber. Proc. Roy. Soc. 128.nDietz, A. G. H., H. Grinsfelder, and E. Reissner. 1945. Glueline stresses in laminated wood. Proc. Am. Soc. Mech. Eng., Nov. 26-30, New York, N.Y.nKennedy, E. I. 1965. Strength and related properties of woods grown in Canada. Can. For. Serv., Eastern For. Prod. Lab., Dep. Pub. 1104, Ottawa, Ont.nLongworth, J. 1971. Checking and delamination of glued-laminated beams. Univ. Alberta, Dep. Civil Eng., Timber Design Seminar, Nov. 16.nMarquardt, L. J., and W. G. Youngquist. 1956. Tension test methods for wood, wood-base materials, and sandwich constructions. U.S. For. Serv., For. Prod. Lab., Pub. 2055, Madison, Wis.n






Research Contributions