Elastic bearing constant of wood: effects of moisture content conditions

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U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 1974

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Page 2 - The experimental arrangement for loading the joints is shown in figure 1. Joint slip was measured with a microformer which allowed for continuous recording of the load-slip curve. The joints were loaded at a constant rate of head movement of the testing machine of 0.10 inch per minute. Each joint was subjected to...
Page 2 - Moisture content —Joints in conditions 1, 3, and 5 were evaluated immediately after assembly. For the other conditions, the joints were assembled and conditioned for 2 to 3 months while the moisture content was being changed. The same members were used for all six moisture conditions.
Page 3 - E = modulus of elasticity of the nail, pounds per square inch; d = nail diameter, inches; and k „ = elastic bearing constant, pounds per cubic inch. This expression has the following restrictions which were met by the joints in this study: (1) Two-member joints made with round nails, (2) both members have the same elastic bearing constant, and (3) the products Xa and Ab are both greater than two, where X-2 (2) ;rEd...
Page 3 - ... experimentally determined P/<5's, slope of the load-slip curves, were used in all calculations.
Page 4 - Average Lb/in. Slope of the load-slip curve Range Lb/in. Elastic bearing constant Lb/in.3 1.22 x 10* Proportional limit slip In.
Page 2 - JOINT SLIP Figure 2. — Typical load-slip data obtained for laterally loaded, nailed joints.
Page 2 - Each joint was subjected to cyclic loading by initially loading to a low level of slip and then gradually increasing the level of slip on each succeeding cycle until a fairly linear Figure 1.
Page 5 - GREEN When the joints were assembled and allowed to dry before evaluation, there was a considerable reduction in the elastic bearing constant, table 5. In drying from the green condition to 17 percent moisture content (condition 2), the reduction...

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