Abstract
Slightly damaged steel members were reused in repairing the bridges suffering from the 1995 Kobe Earthquake. The earthquake loads may have induced cyclic plastic strains into the steel members. The cyclic plastic strains will decrease the high-cycle fatigue strength for the vehicular loads afterward. In this study, regarding the cyclic plastic strains as low-cycle fatigue, we investigate the influence of the damage generated by the low-cycle fatigue on the high-cycle fatigue strength. The columnar speciments with stress concentration are damaged by low-cycle fatigue, and then they are subjected to high-cycle fatigue. Based on the obtained results, we establish the S-N formula for the steels subjected to cyclic plastic strains.
