Abstract
This research evaluates the effect of simultaneous high speed train loadings on double-track for the fatigue design of railway concrete bridges by using a numerical analysis. Concretely, this research examines the tensile fatigue strength by defining the probability density curve of the shift time from train schedule diagram, and by using section force-time relation of simultaneous train loadings. This research clarifies the following items: firstly, regarding tensile fatigue strength, the effect of increase of the section force by uplift is more dominant than the effect of simultaneous train loadings. Secondary, the simultaneous train loadings coefficient b which expresses the effect of simultaneous train loadings in the current fatigue design doesn't become the determination factor for the fatigue design. Thirdly, the simultaneous train loadings coefficient b may be considered zero in general.
