Modelling the Residual Design Resistance of Axially Loaded Structural Steel Members Under Various Corrosive Environments.

Abstract

Atmospheric corrosion accelerates age-related structural degradation, impacting the structural integrity of steel elements over time. Design codes offer broad guidelines to mitigate corrosion effects, yet limited research has explored realistic corrosion thickness loss models across diverse environmental conditions. This study investigates the behaviour of axially loaded corroded steel sections exposed to varying atmospheric corrosivity levels. Five critical corrosion loss models are proposed, encompassing scenarios from control specimens to uniform and varying thickness loss models. The selection of the corrosion rate model aligns with ISO 9224 guidelines, estimating steel thickness loss over time and exposure conditions. Utilizing EN 1993-1-1 guidelines, an analytical framework is developed to model the post-corroded residual cross-section resistance of axially loaded steel members throughout their service life. This study identifies crucial changes in section class, especially for compression members, and delineates variable reduction factors of resistance across different corrosive environments. This work outputs an open-source user-friendly graphical user interface where the residual strengths could be obtained for a given section, design life, corrosion model, and exposure levels. For example, it is shown that the original compressive design resistance of a 203x203x86 Universal Column section drops by 100%, also from class 1 to 4 due to vanishing web, at the end of six years in the presence of critical CX and CM4 conditions. Therefore, by integrating realistic corrosion models and analytical approaches, this research aims to enhance the understanding and prediction of structural behaviour in corroded steel elements, facilitating more robust design and maintenance practices for infrastructure resilience.