In order to understand the effects of various factors on fatigue life of concrete under varying repeated load, two-stage and three-stage stress fatigue tests were performed. As the factors, the order of repeated loads, the number of cycles in initial stress level (S1) n1, and the following stress level S2, S3 were selected. Since the values of fatigue life of concrete are known to scatter widely, the fatigue test results were evaluated statistically.
The experimental results show the followings:
(1) The sum of cycles ratio for the same test condition follows a logarithmic normal distribution.
(2) The estimation of fatigue life with Miner's rule predicts on the unsafety side when the initial stress level is higher than the following stress level.
(3) The Miner's rule, however, may be applicable for the prediction of fatigue life of concrete under varying repeated load when the order of repeated load is uncertain.
