Damping and Stiffness of Nailed Joints: Response to Drying
Keywords:
Damping, stiffness, slip, energy absorption, energy capacity, nailed joints, wood, plywood, testing, moisture contentAbstract
On the West Coast, Douglas-fir components are usually assembled into structures in green or semi-seasoned condition, and as they dry during initial service life, gaps often develop between the contact surfaces of the wood joints. The effect of such gaps on joint damping and slip variables was evaluated using cyclic-load tests on single-nail joints constructed with Douglas-fir stud and plywood sections. The stud sections were exposed to various changes in moisture content before and after joint assembly.
Observed damping ratios and slip moduli were significantly smaller for joints with gaps (assembled green and tested dry) than for those without gaps (assembled and tested at the same moisture content). Increases in load magnitude decreased slip modulus and increased damping ratio of joints with interlayer gaps, but decreased damping ratio of those without such gaps. Variations in surface roughness of the stud (from machining) affected neither damping nor stiffness significantly.
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