Dynamic responsive characteristics of nailed plywood-timber joints under harmonic vibrations

Abstract

Dynamic tests of nailed plywood-timber joints are conducted under harmonic vibrations from 2 to 7 Hz. The principal results are as follows: under dynamic loading, nailed plywood-timber joints may break in low-cyclic bending fatigue failure of nails besides the other failure modes typical under static loading. The dynamic response of nailed plywood-timber joints is clearly dependent upon both the input frequency and the acceleration. These responsive characteristics arise from the nonlinear load-slip relationships and the characteristic cyclic stiffness degradation of nailed joints; that is, the cyclic degradation of the equivalent linear stiffness decreases the resonant frequencies of the same joints, which results in a transition of dynamic responses. It indicates that frequency components of seismic waves resonant to the frequencies corresponding to safety-limit stiffness of nailed joints may lead them to critical failures, even if the accelerations do not exceed the accelerations equivalent to the static damage-limit resistance. © 2012 The Japan Wood Research Society.