Research on Fatigue Behavior of Arch Bridge Suspenders Based on Train-Track-Bridge Dynamic Interaction

Research on fatigue behavior of arch bridge suspenders is of great significance to the bridge design and maintenance. The dynamic stress responses of suspenders calculate by the static influence line method in the code, because track irregularities and the mutual vibration between the trains and the track-bridge are ignored, the dynamic stress cannot accurately reflect real stress response when the trains passes bridges. To more accurately calculate fatigue behavior of arch bridge suspenders, this paper presents an approach based on train-track-bridge dynamic interaction to calculate the dynamic stress time history of the suspenders. Fatigue stresses spectrum is obtained by the rain flow counting method, and used the S-N curve to calculate fatigue life of the suspenders. Taking a through tied arch bridge as an example, static influence line method and the proposed method are used to calculate fatigue damages of the short suspenders and the secondary short suspenders, respectively. The results show that fatigue damages of secondary short suspenders are more serious than the result of short suspenders under the action of train loads, which is the weak position of fatigue failure, it should be paid more attention during the operation of the arch bridge. The fatigue damage calculated by train-track-bridge method is larger than that by static influence line method. Although the result of the static influence line method ensures the fatigue safety of the suspenders in the design, it has a large error with the actual results.