Abstract
Partly pulsating tension load with the frequency range of 1Hz to 16.7Hz was applied to timber butt-joints with metal plate connectors. The time dependent effect on fatigue strength was discussed with respect to the relation between cycles to failure (N) and loading components, i. e., repetitive load (Pr) and constant load (Pc). The results obtained are as follows;
(1) N obtained by partly pulsating tests at 16.7Hz and 10Hz did not depend on Pc but dominantly on Pr, when the sum of Pc and Pr was less than 70% of the static strength (Po) and Pr was grater than the fatigue limit (Pe).
(2) The failure mode of the joints in partly pulsating tests was mostly the withdrawal of teeth of the connector. This tendency was observed only in high stress levels of pulsating tests.
(3) In lower frequency tests at 5Hz and 1Hz, N decreased to 1/2 (5Hz) and 1/3 (1Hz) of the value of N obtained in 10Hz tests, when Pr/Po was from 0.4 to 0.6 and the sum of Pc and Pr was 750kg.
