In a Robinson type steel-concrete composite deck, headed studs and rib plates are usually welded on its bottom steel plate. The authors have investigated a welding ferrule to realize improved headed studs with higher durability. In contrast, the weight of bottom steel plate generally occupies about 55% in a whole weight of the Robinson type steel-concrete composite deck. On the bottom steel plate welded with rib plates, the thickness of bottom steel plate such as 8mm or 9mm is usually used, because there is concern about its thermal deformation in welding. A cold tandem welding method, which is recently used, can reduce heat input and suppress the thermal deformation of the bottom steel plate. Then, it has been possible to adopt a thinner steel plate such as 6mm to the bottom steel plate. To achieve a rational fatigue design, the tensile fatigue strength of such a thin steel plate welded with headed studs or rib plates has to be evaluated. The aim of this study is to compare the tensile fatigue strengths of a steel plate welded with each conventional and improved headed stud or a rib plate with the fatigue design recommendations of JSSC. From the fatigue test results, it was confirmed that the fatigue strengths of the steel plate welded with each conventional and improved headed stud satisfied E-grade of JSSC. Furthermore, the steel plate welded with a rib plate also satisfied E-grade of JSSC.
