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ABSTRACT
This study investigated the bending strength of T-type, staple-glued plywood gusset-plate joints constructed of wood composites to provide the background information needed to formulate expressions for predicting the bending strength of the gusset-plate type joints for upholstered furniture frame construction. Test results indicated that the bending strength of gusset-plate joints was significantly affected by gusset-plate thickness, width, and length. Among the plate size parameters, plate width affected joint bending strength the most. The bending strength of joints constructed with 5-inch-wide plates averaged two times as strong as joints constructed of the 3-inch plates for the same plate length and thickness. Joint member material type and the number of staples had no effect on bending strength. The average bending strength of the joints ranged from 6,073 to 18,528 lb.-in. with plate sizes from 1/4 by 3 by 6 inches to 3/8 by 5 by 10 inches. In general, the bending strength of gusset-plate joints could be predicted by means of an expression relating width, length, and thickness.
In order to perform rational design of upholstered furniture frames to meet specified strength and durability requirements, furniture manufacturers demand strength design data for various types of joints to select the appropriate joint type for their special frame construction design. Presently, formulas have not been fully developed to predict the bending strength of staple-glued plywood gusset-- plate joints as a function of various joint parameters such as gusset-plate sizes and material properties. With the increased use of engineered composite materials in upholstered frames, it is increasingly important that the strength of gusset-plate joints constructed of composites be evaluated and expressions developed to predict their strengths.
Presently, only limited information is available concerning bending resistance of gusset-plate joints constructed of wood composites. To study strength and stiffness of joints with gusset-plates, Eckelman' constructed T-shaped joints of Douglas-fir with different configurations of gusset-plates: right-rail-fit gussets (gusset-plates had the same widths as rails), oversize rectangular gussets, and triangular-shaped gussets. Experimental results indicated that the joints were not particularly sensitive to construction variables such as the number of staples and how tightly they were pulled down. Rather, the strength of the joints was limited by the strength of the gusset-plate materials, and in particular, by the rolling shear strength and...