PSI - Issue 79

Abubakr E.S. Musa et al. / Procedia Structural Integrity 79 (2026) 206–216

207

Keywords: Corroded tube; plastic buckling; initial imperfections; intended imperfections; unintended imperfections; finite element; steel tube; axial behavior © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IGF28 - MedFract3 organizers 1. Introduction Steel tubes are widely used in steel construction, either as standalone structural elements or filled with concrete to form concrete-filled steel tubes (CFSTs), which function as composite members capable of carrying significant loads ((Lai et al. (2020), O’Shea and Bridge (2000), Zhanshuan (1984)). However, these tubes are susceptible to various imperfections, such as thickness reduction caused by corrosion, dent, and out-of-roundness. Axially loaded tubes are particularly prone to buckling failures, with their buckling resistance influenced by these imperfections. The impact of imperfections varies with the radius-to-thickness (R/t) ratio, similar to circular cylindrical shells (CCSs). In fact, circular tubes and CCSs share several stability characteristics. For example, a cylinder is considered a tube when the R/t ratio is small, while it is categorized as a CCS for larger R/t values, which can exceed 500 in some applications such as tanks and silos. The type of buckling experienced by axially loaded cylinders also depends on the slenderness ratio (L/R) and the R/t ratio. Cylinders with large L/R ratios are more likely to experience global buckling, whereas local buckling predominates in cylinders with smaller L/R ratios (Musa et al. (2023), Rotter (2008)). Additionally, for small L/R values, cylinders with low R/t ratios are prone to plastic buckling, while those with high R/t ratios typically undergo elastic buckling. Intermediate R/t ratios may result in elastic-plastic buckling behavior (Musa et al. (2024)). A substantial body of literature has explored the impact of geometric imperfections on circular tubes and CCSs. Both localized imperfections, such as dents or weld depressions, and distributed imperfections, like out-of-roundness, significantly influence the structural performance of these structural elements. For instance, an experimental study by Ghazijahani et al. (2014) examined the effect of dent imperfections on steel tubes, showing that the maximum reduction in buckling load was approximately 25%. While this reduction is relatively small, dent imperfections in structures with large R/t ratios can cause a much more pronounced decrease in buckling strength, exceeding 52% (Musa et al. (2022)). Similarly, other studies have demonstrated that dent imperfections can reduce the shell buckling strength by nearly 50% (Ayd  n Korucuk et al. (2019), Gavrilenko (2004), Gavrilenko and Krasovskii (2004b, 2004a) and Krasovsky and Evkin (2021)). It is important to note that the type of imperfection plays a critical role in determining its impact. Some imperfections, such as cut-outs or thickness reductions caused by corrosion, can significantly decrease buckling strength, even in cylinders with small R/t ratios. For example, Ghazijahani et al. (2015) conducted an experimental study investigating the influence of cut-out imperfections on steel cylinders with an R/t ratio of 23.8. The results showed a considerable reduction in buckling strength, attributed to the decrease in the cylinder’s cross-sectional area, which leads to a redistribution of the load. Corrosion-induced thickness reduction is a common issue in practice, with its effect on buckling strength expected to resemble that of cut-out imperfections, depending on the severity of the thickness loss. Furthermore, the distribution of corrosion along the cylinder's surface can significantly influence its structural behavior. This study is part of an ongoing project to examine the impact of corrosion-induced thickness reduction on the buckling strength, considering key parameters such as the extent of thickness loss and its location along the cylinder's height. The primary objective of the current study is to develop a reliable finite element (FE) simulation approach for corroded steel tubes using ABAQUS software, enabling detailed and efficient future parametric studies. Eight steel tubes were prepared and tested to evaluate the effects of varying levels of corrosion-induced thickness reduction. The experimental results were used to calibrate and validate the developed FE simulation approach.