Modeling of concrete response under fatigue

A numerical approach to modeling the response of structural concrete under fatigue load is proposed. It aims at realistic predictions of concrete degradation in context of structural lifetime assessment. The approach is essentially based on the material model for concrete developed within the uniform framework of the elasto-plastic continuum damage theory, which is presented in the companion paper (Bockhold et al. 2003). The present contribution improves the classical fatigue curve (S-N curve) approaches by nonlinear evolution laws for fatigue strains and damage. Besides estimates of the fatigue failure itself, it is able to predict the intermediate material states of concrete during fatigue life. The model is statistically founded and accounts for uniaxial loading conditions. Its theoretical extension to multiaxial fatigue as well as a supporting experimental program are currently in progress. The approach is illustrated by a numerical example of reinforced concrete column under cyclic loading.