Sectional Analysis of Concrete Structures under Fatigue Loading

Fatigue is a continuous and progressive microcracking mechanism leading to increasing permanent strains and decreasing stiffness in concrete. This paper proposes a time-dependent (i.e, cycle-dependent) model for concrete that accounts for the changes of the mechanical properties during the fatigue life. The proposed method can be useful in estimating the fatigue-carrying capacity of existing structures that will be subjected to higher loads in the future. The model is implemented into a sectional algorithm to reproduce the evolution of the stress-strain state of reinforced concrete members. Redistribution capacity is found to be the main governing factor of the final failure mode. A comparison of theoretical results with existing experimental data of reinforced concrete beams indicates that the model is accurate in the prediction of strain evolution, fatigue life and the mode of fatigue failure.