Fatigue behavior of HPC and FRC under cyclic tensile loading: Experiments and modeling

Systematic investigations of hardened cement paste, high-performance concrete and mortar with and without microfibers, subjected to static and cyclic tensile loadings, were conducted. The material degradation was investigated by means of microscopic analyses of the microcrack development. Notched specimens were subjected to a predefined number of load cycles. A nonsteady increase of microcracking with increasing load cycles was observed in high-strength concrete, whereas the addition of steel fibers lead to a steady increase of microcracks. High-strength mortar often showed premature failure, while addition of steel micro fibers allowed completion of the cyclic tests. To obtain a deeper insight into physical mechanisms governing fatigue and structural failure, high-performance concrete (HPC) and fiber-reinforced concrete (FRC) under static and cyclic tensile loadings have been modeled using cohesive interface finite elements, micromechanics, and a fiber-bundle model. Analysis of model predictions shows the significance of strength disorder and fiber properties on the structural behavior.