Strengthening column-beam joint areas damaged by corrosion with composite materials

Specific studies have been conducted to minimize performance losses caused by corrosion damage in reinforced concrete structures exposed to earthquake loads and to provide necessary reinforcement. Corrosion in reinforcement in reinforced concrete structures occurs due to environmental factors, workmanship errors, and other factors. This leads to a loss of strength, rigidity, and ductility, and over time, leading to structural damage and increasing the risk of collapse. In this context, strengthening with CFRP composite materials restores the structure's former strength and provides significant economic advantages. An examination of the existing building stock in our country reveals that many structures fail to meet strength requirements, and rebuilding them leads to significant cost increases. Therefore, instead of demolishing and rebuilding structures with corrosion damage, reinforcing CFRP, particularly in the column-beam joint areas most vulnerable to earthquake stress, offers significant benefits in terms of both economics and functionality. In this study, a total of six column-beam joints, including one uncorroded and one corroded reference specimen with identical reinforcement arrangements, were fabricated. The effects of corrosion on the joints were investigated under reversible cyclic horizontal loading. In the experiments, CFRP composites were applied to the joints, beam surfaces, and column spans with epoxy. Reversible cyclic horizontal loading was applied to the system from the beam end region. Load-displacement data obtained during the experiments were used to generate envelope curves, cumulative energy dissipation graphs, and stiffness curves, and ductility values were calculated. The obtained results were used to investigate the effects of corrosion on the strength parameters such as bearing capacity, ductility, and energy dissipation capacities of damaged joints before and after reinforcement with CFRP composite.