Experimental and numerical investigation on seismic performance of corroded RC columns of low-strength concrete

Abstract

A huge number of reinforced concrete structures designed without aseismic consideration exist at the risk of both reinforcement corrosion and earthquake. They were generally made of low-strength concrete and loaded with a relatively large compression ratio. A total of 11 RC columns of low-strength concrete with different corrosion degrees were obtained by the impressed current method, and low-cycle repeated loading tests were carried out on the columns with axial compression ratios ranging from 0.25 to 0.75. The seismic performance of corroded RC columns of low-strength concrete was analyzed through a discussion of the impact of reinforcement corrosion on failure modes, hysteretic behavior, skeleton curve, and energy dissipation capacity. For a more comprehensive understanding of the seismic performance of corroded RC columns, a numerical model based on the multi-spring model was developed by introducing a restoring model of corroded rebars. The numerical simulation results showed a good agreement with experimental results. With the verified numerical model, the influence of concrete strength, reinforcement ratio, and axial compression ratio on the impact of reinforcement corrosion on the seismic performance of RC columns was further investigated. It is found that the seismic performance of RC columns decreases rapidly with the increase of axial compression ratio and corrosion degree. As the axial compression ratio increases, the impact of reinforcement corrosion on the seismic performance is gradually weakened owing to the decreased contribution of longitudinal rebars to the load-carrying capacity. For similar reasons, the impact of reinforcement corrosion is more obvious in RC columns of low-strength concrete with a larger reinforcement ratio.