Study on hysteresis constitutive and fracture behaviors of corroded constructional steel under artificial atmospheric environment

In order to evaluate the seismic capacity of corroded steel structures in natural atmospheric environment, 18 steel plates with 6 corrosion ages obtained by artificial accelerated test were employed to the cyclic loading tests. A comprehensive corrosion parameter (D) considering the uniform and pitting corrosion was proposed, and used to study the effect of corrosion on the resistance and hysteretic behavior of corroded steel. The results showed that, with increase of D, both of the position of skeleton curves and the peak values of stress cycles were decreased significantly, the yield platform disappeared, and the elastic modulus and ultimate strength decreased sharply; D was also closely related to its energy-dissipating capacity. Then, D was applied to optimize the constitutive parameters and fracture parameters, and a Chaboche plastic constitutive (CPC) model was estab-lished to simulate the hysteretic behavior of corroded steel with very high accuracy. Besides, the relationships of fracture parameters (& epsilon;pl and G) and D were also given. Finally, combined with fracture morphology, the fracture analysis of corroded steel under cycle load was performed. The dimples size on fracture was reduced with in-crease of D, the ductility would be degraded. While D greater than 4.8, the change rate of & epsilon;pl and G showed a sudden change, that meant the fracture behavior tends to brittleness, and should be paid more attention to in the seismic reinforcement design of existing steel structure.