Double-layer four-line railway steel truss girder cable-stayed bridge fatigue design method

The invention relates to a fatigue design method for a double-layer four-line railway steel truss girder cable-stayed bridge, and the method comprises the steps: obtaining the multi-line coefficients of different members of the cable-stayed bridge, and then designing the corresponding members according to the multi-line coefficients of the members, the members comprising an upper chord member, a lower chord member, a diagonal web member, a vertical web member and a stay cable. According to the method, the multi-line coefficients corresponding to different components of the upper chord, the lower chord, the diagonal web members, the vertical web members and the stay cables are obtained, then the corresponding components are designed according to the corresponding multi-line coefficients, compared with standard unified value taking, the fatigue characteristics of the different components can be better reflected, and the fatigue performance of the components is improved. The fatigue design of different component