Effects of residual stresses on the tensile fatigue behavior of concrete

The influence of Eigenstresses due to drying shrinkage on the development of residual deformations characterizing the tensile fatigue behavior of concrete is analyzed. During the loading phase the Eigenstresses are locally released around the cracks inducing a mismatch between the crack surfaces which inhibits a perfect crack re-closure. The analysis is performed by means of a 2D mesoscale implicit finite-element model. The shrinkage strain is first applied determining the development of a diffused micro-damage and then quasi-static loading-unloading tests are simulated. Different microstructures and different values of shrinkage strain are considered. The results show that the presence of residual stresses increases the amount of total dissipated energy and naturally leads to the development of residual deformations. However, the obtained values are only a portion of the residual deformations experimentally measured. The possible concomitant effect of another mechanism, namely the formation of debris at a small scale, is therefore discussed.