Waveform Effect on Fatigue Behaviour of Laterally Loaded Nailed Timber Joints

摘要

Cyclic fatigue is a damage process that can occur in structural timber joints during events such as cyclones and earthquakes. The loading waveform is a crucial factor controlling the rate of damage accumulation and study of that is essential for complete understanding of the process. In the study reported here repetitive square, sinusoidal and triangular loading waveforms were applied to timber joints with one laterally loaded steel nail. Two load levels and two loading frequencies were employed and hysteresis loop areas analyzed to describe in-elastic energy losses. Major findings were: (1) the waveform and frequency governed the fatigue lives of joints, (2) the square waveform was the most damaging amongst those investigated, (3) the dominant ultimate failure mechanisms were ductile necking of nails and brittle planar fracturing of nails, and (4) fatigue processes were not uniform across the loading variables of frequency, waveform and peak load level.