SEISMIC ASSESSMENT OF EXISTING CIRCULAR HOLLOW RC PIERS SUBJECTED TO CORROSION THROUGH NLFEA

The capacity assessment of existing Reinforced Concrete (RC) bridges is a fundamental step to define rational intervention and retrofit strategies. Most of the Italian RC bridges date back to the second half of the last century and were therefore designed for gravity loads only or according to obsolete seismic codes, with inadequate structural detailing and poor-quality construction materials. The situation is further aggravated by aging and degradation over time, together with the limited maintenance level, which can lead to an increase in the seismic vulnerability of the infrastructure. Reinforcement corrosion is a major factor in the reduction of the seismic performance of RC bridges over time and can modify the expected failure mode of primary bridge components, such as piers. To investigate the effect of corrosion on RC piers, a non-linear finite element (NLFE) approach is presented in this work, based on the adoption of the PARC_CL 2.1 crack model, developed at the University of Parma, Italy, for RC elements subjected to cyclic loads and implemented as a user subroutine within the Abaqus FE package. Among the most remarkable features of the model stands out its capability to accurate simulate rheological phenomena, shear failures, reinforcement buckling, as well as the effects of corrosion on the structural response over time. The effectiveness of the proposed approach in the case of bridges is first proved through comparison with experimental data available in the literature on circular hollow RC piers. Finally, the model is applied to evaluate the time-varying capacity reduction of RC piers under aggressive environmental conditions, by considering the decay of the mechanical features and the role of rebars’ buckling.