Multiphysics modelling and structural analysis of RC bridge columns exposed to chlorides under cyclic loading

Long-term performance analysis of reinforced concrete (RC) infrastructures subjected to deterioration phenomena induced by the exposure to corrosive environments is a truly challenging task. Nonetheless, it is essential for designing new structures as well as for predicting the residual life of existing constructions or for planning suitable maintenance interventions. Within this framework, chloride-induced corrosion deserves special attention because of its serious consequences on the reliability of RC members. Therefore, the present work illustrates a comprehensive computational framework meant at supporting the long-term forecasting of the structural performances of RC bridge columns exposed to chlorides. Specifically, chloride ingress in the crosssection of the column is accurately simulated considering the concurrent effects due to temperature, humidity, aging and corrosion-induced cover cracking. Once the partial differential equations governing such problem are solved through the finite element method within the computer program COMSOL Multiphysics, the loss of reinforcement steel bars cross-section is calculated based on the estimated corrosion current density. On the other hand, the nonlinear cyclic response of the RC bridge column under corrosion is determined within the OpenSEES platform by discretizing its cross-sections into several unidirectional fibers, also accounting for the bucking of the corroded longitudinal rebars. The results obtained for a real case-study are finally discussed in order to explain the role of the longitudinal rebars buckling on the time-variation of capacity and displacement ductility. This numerical investigation is supported by a convenient parametrization of the corrosion phenomenon that allows to effectively explore the influence of the chloride-induced pitting corrosion pattern (i.e., number, position, and morphology of the pits) on the overall behavior of the column.