The preventive maintenance method of cutting and treating the semi-circular at the vertical stiffeners in the orthotopic steel decks is often used. The authors conducted fatigue tests of the out-of-plane gusset welded-joint specimens by cutting and treating the semi-circular in the previous paper, however, it was not confirmed the effect of the semi-circular method due to the difference in boundary conditions with the actual orthotropic steel deck. Therefore, in this study, finite element analysis and fatigue tests using the box-type specimens were conducted to confirm the effectiveness of the semi-circular method. As a result, it was clarified that the fatigue strength is improved due to the reduction of bending moment at the weld toe by the semi-circular method.
