Investigating the residual design resistance of steel members under pitting corrosion

Abstract

Pitting corrosion is a localised form of corrosion that results in the formation of small cavities on the steel surface, leading to a significant reduction in strength. Assessing the residual design resistance under such degradation is crucial, as this deterioration can impact structural integrity. This study investigates the effects of pitting corrosion on the residual design strength of steel members through comprehensive experimental and numerical analyses. The influence of key pitting characteristics, such as pitting intensity, location, and distribution, is examined. The experimental investigations were conducted on Square Hollow Sections (SHS) with artificially introduced local pits on the surface of the members.The SHS specimens were subjected to axial compression tests to assess the impact of localised corrosion on their load-bearing capacity. SHS with uniformly distributed and randomly distributed pits were tested while maintaining the same degree of pitting intensity. A Finite Element (FE) modelling method was employed to replicate the test specimens to validate the experimental test results by comparing the ultimate loads and failure modes. The validated FE models were used to analyse the nature of random pitting of the members in terms of statistical analysis. The validated numerical results show that the random pitting distribution causes greater reduction and variation of design resistance, along with varied failure patterns. It is observed that including pits reduces the design resistance of specimens by 12-16% for the selected degree of pitting intensity in this study. The maximum strength reduction occurs when the pits form in the middle of the specimen, indicating a critical vulnerability in the structural integrity under pitting corrosion.