Efficient Fabrication of Glued-Laminated Timbers

by James W. Johnson, Assoc. Prof.; Forest Res. Lab., School of Forestry, Oregon State Univ., Corvallis, OR,

Serial Information: Journal of the Structural Division, 1973, Vol. 99, Issue 3, Pg. 431-442

Document Type: Journal Paper


Fifty-four large glued-laminated timber beams were designed, fabricated, and tested to failure in static bending. Designs included several levels of moduli of elasticity (MOE) and rupture (MOR). Beams were made from lumber of Southern pine, Douglas fir, hem-fir, and Lodgepole pine; they were 40 ft (12 m) long, 5 in. (13 mm) wide, and 24 in. (610 mm) deep. Individual pieces were evaluated by nondestructive testing (NDT) techniques for MOE before laminating. Results indicated several advantages for NDT methods in construction of glued-laminated beams. The lumber available can be located in the beam to gain maximum stiffness (MOE) and good strength (MOE). MOE of the beams was highly predictable; MOR was less predictable, but met the desired stress level. Based on the research, specifications have been published, which provide for the use of several additional species of lumber, nondestructively tested in glued-laminated beams.

Subject Headings: Wood beams | Fabrication | Laminated materials | Wood | Construction methods | Material failures | Failure analysis | Structural failures

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