Experimental study on the low-cycle loading behaviour and constitutive relationships of accelerated corroded steel plates

Through monotonic tensile tests and low-cycle loading tests on six groups of accelerated corrosion specimens, the monotonic and low-cycle loading behaviour of corroded steel are discussed. A non-uniform corrosion damage parameter, Dn, is applied to study the degradation laws of monotonic and cyclic loading properties due to corrosion. Experimental results indicate a significant difference in the mechanical response of corroded steel under cyclic and monotonic loading. Cumulative cyclic damage leads to premature necking and fracture, with limited effect on the strength of steel. With the increase of Dn, the yield strength, tensile strength, elastic modulus, and necking strain of corroded steel all show a linear decreasing trend, accompanied by a significant reduction in energy dissipation. Based on a comprehensive understanding of the cyclic loading behaviour of corroded steel, the mathematical models for the initial loading curve, cyclic skeleton curve, reloading curve, and unloading curve are proposed. The variation laws of model parameters with Dn are analyzed to establish the cyclic constitutive relationship of corroded steel. The comparison between the model curve and the experimental curve verifies the accuracy of the proposed model.