In this study, fatigue cracks at the flange ends of cross ribs in box girders were reproduced through fatigue tests, and the effectiveness of simple repair methods was confirmed. Additionally, the possibility of detecting fatigue cracks by measuring static strains without loading was verified. As a result, it was found that methods such as closing fatigue cracks with an automatic center punch, bolting the cracks, and the patch plate method could delay the initiation and propagation of fatigue cracks. Moreover, it was revealed that fatigue cracks at the flange ends of cross ribs could be detected by measuring static strains near the welds.
