Combined compression-bending performance and design of CFST with localised pitting corrosion

Abstract

This paper presents a comprehensive numerical study on the combined compression-bending performance of concrete-filled steel tubes (CFSTs) considering the commonly seen localised pitting corrosion damage in the marine environment. An advanced finite element modelling technique is utilised to simulate the localised corrosion pits on the outer surface of the steel tube considering its random nature. The differences between the load-moment interaction of CFSTs with uncorroded conditions, uniform corrosion simplification and pitting corrosion are discussed. The analytical results reveal the impact of localised pitting corrosion damage on the combined compression-bending performance of CFSTs can be grouped as the stress concentration around corrosion pits, premature local buckling of steel tubes and the reduction in effective confinement. An extended parametric study illustrates that the confinement factor and the mean pit depth have a considerable impact on the combined compression-bending behaviour of CFSTs with localised pitting corrosion. The feasibility of utilising existing design approaches calculates the load-moment interaction diagrams of locally pitted CFSTs following the DoV-based uniform corrosion simplification is evaluated. On this basis, simplified design methods accounting for the characteristic of pitting corrosion are proposed for estimating the post-corrosion load-bearing capacity of CFSTs under combined compression and bending, and reasonable accuracy is achieved.