Abstract
Direct-tension and splitting tensile fatigue tests were performed on air-dried and wet concrete. The conditions in the fatigue test are following ; 10×10×40 cm and 10φ×17 cm specimens, loading at 1H_z and S_<max>=(0.9〜0.7)S, S_<min>=(0.1〜0.4)S. The following conclusions were obtained from the tensile fatigue test results on plain concrete. (1) The relation between the loading stress ratio and the number of cycles to failure in the tension fatigue is different for air-dried and wet concrete; and the fatigue life in wet concrete is shorter than the dryed one under the same test conditions. (2) When direct-tension and splitting tensile fatigue are compared each other, the fatigue life in splitting tensile test is smaller than the former test under the same minimum stress ratio. (3) The fatigue strength of concrete in the splitting tensile test is lower about 20 % than that in the direct-tension test. (4) The following expressions were derived for air-dried concrete. S_<max>=1-0.0285(1-log (S_<min>)) logN_f where, S_<max> is the maximum stress ratio for the ultimate strength, S; Smin is the minimum stress ratio for the ultimate strength; N_f, is the number of loading cycles at fatigue failure.
