Pulsating tension fatigue tests were made of Hi-Strand and of JIS PC-strand, and the following conclusions have been obtained:
(1) Hi-Strand and JIS PC-strand have almost same fatigue strength at N=106 in stress amplitude, and as the former has larger ultimate tensile strength and larger yield strength, the fatigue strength diagram (in σa-σm representation) of Hi-Strand is extended along the abscissa (σm), the values of the ordinate (σa) remaining unchanged.
(2) But at N=107, it is expected that Hi-Strand has smaller allowable stress amplitude for fatigue, so if the fatigue behavior of PC-strand is brought into question, the materials which have very high tensile strength are not preferable.