ABSTRACT
Both of toe cracks and root cracks are developed in fillet welds. Since root cracks are initiated at the inside of fillet welds, they are difficult to be detected. When root cracks appear on the weld bead surface, they can be propagated to beneath the surface. Because these cracks are so dangerous that can break out weld bead, it is required to detect them when the cracks are not so long required. The purpose of this study is to reproduce root cracks in transverse fillet welds between sole plates and bottom flanges of steel girders using small specimens with a gap between sole plate and bottom flange. The main cause of these cracks produces is high compressive stress by lack of bearing movability. Static loading tests are conducted in order to grasp the relation between loading location and the stress distributions. Fatigue tests were conducted using two specimens. The first specimen was loaded near the center of the sole plate. Its loading condition was decided from result of static loading test. The second one was loaded on the edge of the sole plate to simulate loading conditions in actual bridge. As a result, root cracks can be recreated on the bead of the fillet welds between sole plate and bottom flange of steel girders by loading edge of sole plate. In the future, we will try to detect root cracks by some non destructive tests.
