Numerical investigation on hysteretic behaviour of corroded T-shaped tubular joints under compressive bending

This study explores the dynamic safety performance of marine structures in long-term service, focusing on the impacts of seawater corrosion damage and dynamic loads on the hysteretic mechanical properties of T-shaped tubular joints. Employing the accelerated electrochemical corrosion method, joints were pre-corroded in artificial seawater. Monotonic tensile experiments were conducted on material test specimens extracted from the chord and brace of a corroded joint. The findings indicate that corrosion significantly degrades the elastic modulus, strength, and ductility of chord and brace steels, with ductility exhibiting heightened sensitivity to corrosion. These test results were integrated into a joint model for numerical analysis, revealing a decrease in strength, stiffness, and bearing capacity of T-shaped tubular joints with increasing corrosion severity. A comprehensive three-segment full-skeleton model of the corroded tubular joints was developed, encompassing elastic, strengthening, and descending sections. Additionally, a cyclic degradation index was introduced to describe the degradation patterns of strength and stiffness. The model considers the degradation effects of corrosion on yield point, peak point, failure point, and loading and unloading stiffnesses. Consequently, a detailed hysteretic mechanical model of corroded T-shaped tubular joints under biaxial loading has been established, contributing valuable insights into the structural integrity of marine structures under corrosive conditions.