Coupled damage model for RC elements assessment under environmental degradation

In the present work, a coupled environmental-mechanical damage model for structural analysis of RC elements subjected to aggressive action - originally developed by some of the authors - is presented and further enhanced, introducing some innovative formulations. In particular the effect on structural performance of rebars corrosion, induced both by chloride attack and carbonation, and of freeze-thaw cycles is analyzed. To this aim, the environmental damage parameter is re-formulated and splitted in two contributions in order to better represent the degradation of concrete caused by cracking due to different processes (e.g. development of expansive products during corrosion, pressure induced by internal ice formation). The proposed models are implemented in the finiteelement framework OpenSees, developed at Berkeley, University of California and validated by comparison with a number of experimental tests. In the first part of the paper the proposed constitutive models are introduced discussing the most relevant features and characteristics. Then, in the second part of the paper, the validation tests are presented and the obtained results are compared with experimental ones, proving that the model is suitably accurate in reproducing the main aspects observed during experiments: i.e. failure load, ultimate displacement and failure mode.