Study on repair methods for fatigue crack on intersection weld of U-shape closed rib and transverse rib in orthotropic steel deck

Hanshin Expressway extends approximately 260 km in total network length, and the network runs through urban areas; thus, almost 80% of the expressway consists of elevated bridge among total structures. More than 50% of the expressway structures have been in use for over 40 years since commencement of service. The time lapse has resulted in acceleration of structure deterioration. Among the deterioration, various types of fatigue cracks have occurred in orthotropic steel decks. This study describes the fatigue cracks occurring at the intersections of U-shape closed ribs and transverse ribs. This study focuses on the effectiveness of temporary treatment by using stop holes to restrain fatigue crack progress and the stress reduction by means of patch plate methods for permanent treatment; furthermore, this study clarifies characteristics and the effectiveness of the patch plate methods by comparing the stress reduction effects on three patch plate types.