Compressive performance and design rule of CHS X-joints with local pitting corrosion

Abstract

Local pitting corrosion poses a critical threat to the structural integrity of tubular joints in marine and offshore structures, yet its effects on CHS (Circular Hollow Section) X-joints remain inadequately understood. This study experimentally and numerically investigates the compressive performance of CHS X-joints with localized pitting corrosion. Five specimens, including both uncorroded and corroded joints fabricated via precision drilling, were tested under axial compression. All joints exhibited chord plastification as the dominant failure mode, and pitting corrosion led to significant reductions in strength and stiffness, especially in joints with larger brace-to-chord diameter ratios. Validated finite element models incorporating the element birth-and-death technique were used to assess the influence of axial and circumferential corrosion positions, corrosion rate, and geometry on joint strength. Results revealed that axial corrosion near the brace-chord intersection was the most detrimental, while circumferential position played a secondary role. Based on parametric analysis and plastic yield line theory, a new design formula was proposed to predict the residual compressive strength of corroded joints, which demonstrated strong agreement with simulation results (96 % accuracy) and offered a practical tool for structural assessment and design under localized corrosion.