An experimental and numerical investigation on the flexural strengthening of full-scale corrosion-damaged RC columns using UHPC layers

When exposed to chloride-rich environments, reinforced concrete (RC) structures have serious concerns about rebar corrosion. In this study, a strengthening method was developed for RC columns with corrosion damage. Five full-scale RC columns with the same dimensions and rebar arrangements were experimented under reversed cyclic loading, where an axial stress equal to 1 MPa was applied to the specimens. Out of the five test specimens, two specimens underwent an average of 10 % rebar corrosion (Group 1), another two specimens underwent an average of 15 % rebar corrosion (Group 2), and one specimen acted as the sound specimen. One specimen from each group was retrofitted with 50 mm thick ultra-high-performance concrete (UHPC) layers. The experimental outcomes showed that reinforcement corrosion reduced ductility and maximum load-carrying capacity (MLC) significantly. The ductility and MLC of the specimen with 15 % rebar corrosion was decreased by 17 % and 9.2 %, respectively, compared to the sound specimen. However, the 15 % corroded specimen strengthened with UHPC layers displayed superior structural performance, for example, the MLC was increased by 24 % compared to the sound specimen. The performance of the strengthening scheme was evaluated using important performance indices, i.e., MLC, ductility, stiffness degradation, energy absorption, curvature distribution, etc. A simplified numerical model was developed and verified with experimental results. Experimental and numerical results revealed that the proposed approach can be very effective in strengthening corrosion-damaged RC columns.