Time-dependent reliability analysis of corroded high-strength steel tube

Abstract

Accurate long-term reliability evaluation is essential for steel tubular structures widely used in corrosive environments. However, existing studies often rely on steel plate data, which fails to accurately reflect the specific corrosion-induced degradation of high-strength steel (HHS) tubular components. In this study, high-strength square steel tube specimens with three strength grades, namely Q460, Q550, and Q690, were investigated. A total of 108 corroded specimens were subjected to uniaxial tensile tests to systematically quantify the effects of corrosion on their mechanical properties. The experimental results indicate that corrosion significantly modifies the fracture characteristics and mechanical response of HHS tubes. With increasing corrosion severity, fracture behavior gradually transitions from ductile to brittle, accompanied by a pronounced reduction in necking at the failure region. Meanwhile, ultimate strength, yield strength, and the corresponding strain values decrease markedly, and the yield plateau is shortened or even eliminated. Comparisons among different strength grades further show that HHS exhibits relatively stronger resistance to corrosion-induced mechanical degradation under equivalent corrosion rate variations. Based on the experimental data, a statistical model for predicting the yield strength of corroded HHS was established. By incorporating representative marine corrosion parameters together with six typical loading conditions, a time-dependent reliability assessment framework for corroded steel tubular components was developed. The proposed methodology and results provide useful reference data for the reliability design and code development of steel tubular structures exposed to marine environments.