Flexural tests of large glued-laminated beams made from visually graded hem-fir lumber Public Deposited
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Fifteen large glued-laminated beams made from visually graded hem-fir lumber were designed, fabricated, and tested to failure in static bending. When tested, the beams had an average moisture content of 7.5 percent. The beams were 40 feet long, 5 t/s inches wide and 24 inches deep. Before laminating, individual pieces of lumber were graded by specifications similar to those for the L-grades and the AITC recommendations for face laminations for Douglas fir. Three combinations (designs) were included, with 5 beams in each.Performances of the beams during testing are tabulated and graphed. Guidelines were established for the grades and locations of material needed for different levels of modulus of elasticity (MOE) and modulus of rupture (MOR). Least values of MOE and MOR obtained from beams of each design were: combination 1, 1,788,000 and 5,350: combination 2, 1,660,000 and 4,580; and combination 3, 1,724,000 and 3,950 psi. Results of the tests will provide a basis for the development of industry laminating specifications for visually graded hem-fir lumber.
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