An experimental and numerical study on the corrosion characteristics of weathering steel-concrete composite beams

Atmospheric corrosion is one of the main factors leading to the failure of steel structures. The corrosion resistance performance of weathering steel-concrete composite beams seriously affects the structural operation and service. Therefore, it is significant to investigate the mechanism of atmospheric corrosion in concrete deck slabs and weathering steel beams, and to analyze the corrosion characteristics of weathering steel-concrete composite beams quantitatively. At present, there is a lack of research in the field of numerical simulation of pitting corrosion of weathering steels. The mechanism of the chromium and nickel elements in weathering steels for corrosion performance needs to be further explored. In this study, accelerated corrosion experiments were carried out on designed specimens of reinforced concrete deck slabs, as well as carbon and weathering steel beams, respectively. After that, finite element simulation model was established using COMSOL to analyze the evolution of steel reinforcement rust layer in reinforced concrete, and to investigate the development of carbon steel pitting corrosion. By introducing chromium and nickel elements into the pitting corrosion model, the protective effect of the corrosion rust layer on the pitting corrosion process of weathering steel was revealed. This filled the gap in numerical simulation of pitting corrosion of weathering steels and provided a reference for the time-varying corrosion of weathering steels. By combining experiments and numerical models, the time-varying corrosion of materials in corrosion conditions was studied for steel-concrete composite beams, provided a reference for the corrosion resistance design of steel-concrete composite beams. According to the corrosion morphology, kinetics, and electrochemical results, the size of corrosion pits and the corrosion rate of weathering steel were smaller than those of carbon steel due to the protection of corrosion products, and it showed better corrosion resistance. The numerical simulation results also demonstrated that chloride ions diffused along the depth direction in concrete, and the corrosion rate of steel reinforcement was lower under the protection of concrete.