Method for calculating fatigue stress of integral node of rectangular concrete filled steel tube combined trussed beam based on hot spot stress

The invention discloses a method for calculating fatigue stress of an integral node of a rectangular concrete filled steel tube combined truss girder based on hot spot stress, and belongs to the technical field of bridge engineering. The method comprises the following steps that the span and the rod piece size of the rectangular concrete filled steel tube combined truss girder are determined; designing three basic load working conditions: the load working condition I is branch pipe tension-compression balance load, the load working condition II is main pipe axial force, and the load working condition III is main pipe bending moment; calculating nominal stress amplitudes of the main pipe and the branch pipe at the node under the action of the three basic load working conditions; and hot spot stress amplitudes of the main pipe and the branch pipe at the node under the action of the three basic load working conditions are calculated and accumulated. Due to the fact that the hot spot stress concentration factor S