Fatigue Crack Propagation and Repair using Crack-Arrest Holes in Trough Girder Railway Bridges

Fatigue cracks have been observed in the welded joints of end diaphragms in steel trough girder railway bridges. These fatigue cracks are thought to result from deterioration of the bridge supports and uneven settlements induced by train loads passing over them. As a simple repair method, crack-arrest holes are often drilled at the crack tips. However, their effectiveness remains unclear, and in some cases, the cracks tend to re-initiate and propagate. In this study, a fatigue test was conducted on an end diaphragm from a trough girder bridge under support conditions simulating those of an actual bridge. Crack propagation behavior and the effectiveness of the crack-arrest hole repair were examined through fatigue test and numerical analysis. In addition, finite element analysis replicating real bridge conditions was performed to clarify the effects of various parameters on the local stress at the edge of the crack-arrest hole. Furthermore, the effect of inserting a bolt into the hole on reducing the local stress at the hole edge was also investigated.