Experimental investigation of a novel finite element model for Southern pine glulam beams

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1990
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Virginia Tech
Abstract

Glued-laminated wood (Glulam) is a versatile material manufactured by gluing two or more layers of wood together with the grain of all laminae running parallel to each other. Glulam beams of many sizes, shapes, and thicknesses can be made. Innovative load-carrying structures such as lattice domes, bridges, and towers can be built using glulam members.

But, since wood is a highly variable and anisotropic material it is often difficult to accurately model the response of wood components in large structures to applied loads. Advanced computer techniques such as finite element analysis are being developed to more accurately model structure response.

The objective of this study was to evaluate the applicability of the isoparametric beam finite element to model the elastic response of straight and curved glulam beams subjected to three load conditions. Four straight and three curved southern pine glued-laminated beams were subjected to bending about their major axis, bending about their minor axis, and combined bending and compression. Strains were measured at various locations using clip-on electrical transducers; and, deflections were measured at three locations along the length. Transverse isotropy and global modulus of elasticity were assumed ,to determine experimentally beam material properties: longitudinal modulus of elasticity and shear modulus. The analysis was performed by using the finite element program ABAQUS.

The experimental and the analytical strain and deflection values of giu1am beams in bending about the major and the minor axes agreed well for most cases. Differences of less than 100/0 between experimental measurements and analytical predictions were found at all locations through the depth of the beams except in the vicinity of the neutral axis. The differences between the measured and the predicted strain and deflections for beams tested in combined bending and axial compression ranged mostly between 0 % and 40 %.

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