Unified analysis for railway train-track-substructure dynamic interaction Part II: train-induced concrete fatigue damage and temporal-spatial evolution

Numerical realization of fatigue damage evolution of concrete structures in railway engineering is a necessity for predicting dynamic performance of train-track-substructure systems. Based on the principle of vehicle-track coupled dynamics, this paper introduced concrete fatigue damage and mortar viscoelasticity fatigue constitutive models and the train-track-substructure dynamic interaction model established in the previous work. The dynamic evolution model of fatigue damage of concrete structures for ballastless track subjected to the cyclic effects of the train was established. In this model, the material fatigue damage constitutive model was used as the control condition, and the stiffness characterization matrix of the concrete structure and the mortar layer was updated in real time considering the loading/unloading, tension/compression state of the stress/strain point of the finite elements. The fatigue damage and residual deformation of the concrete structure under the action of the previous train were taken as one of the initial conditions of the dynamic equation of the next train-tracksubstructure dynamic interaction, and the coupled time-varying analysis of the spatial vibration and fatigue damage evolution for this unified system was realized. The numerical results show that this model can effectively reveal the three-stage development characteristics of the fatigue damage of the mortar layer; there are significant differences in the fatigue damage evolution rate, the most unfavorable damage mode, location and form of the track slab and the mortar layer; and the influence of structural fatigue damage on the dynamic response of the train-track-substructure system mainly occurs in the last development stage. © 2023, Central South University Press. All rights reserved.