Seismic Performance of Corroded RC Bridge Piers Strengthened with UHPC Shells

Previous studies have investigated the enhancement of the chloride-corrosion resistance of reinforced concrete piers using ultra-high-performance concrete (UHPC) shells. However, these studies did not consider the combined effects of retrofitting time, UHPC shell thickness, and axial loads applied to the piers. To address this research gap, this study conducted numerical simulations, analyzing the seismic performance of retrofitted piers under different UHPC layer thicknesses (30 to 50 mm), service lives (50 to 85 years), and axial compression ratios (8%, 16%, and 24%). First, we briefly outlined the material property degradation characteristics of bridge piers. Then, using rectangular piers as case studies, numerical simulations were conducted on the cyclic performance of corroded piers. The results demonstrated that the strength of piers retrofitted before 70 years, even using a 30 mm thick UHPC shell, was greater than that of pristine RC piers across all axial loadings. For piers retrofitted with a 50 mm thick UHPC shell, the SRPF and SRYF reached about 1.4 and 1.5, respectively. The energy dissipation capacity and stiffness of the UHPC-retrofitted piers increased with the increase in the UHPC thickness and axial compression ratio. The research results of this study offer a useful reference for the seismic retrofitting of corroded piers using UHPC.