Axial compressive behaviour of corroded concrete-filled high-strength steel tubular columns

Abstract

This study investigates the degradation of the axial compression performance of concrete-filled high-strength steel tubular (CFHST) columns following chloride corrosion. The morphology of the corroded steel tubes was analyzed before the axial loading test. After 180 days of corrosion exposure, the depth of the corrosion pits ranged between 1.07 mm and 1.58 mm, displaying a normal distribution. Thirteen concrete-filled steel tubular columns, consisting of normal-strength and high-strength steel tubes, were tested under axial loading. The study examined the effects of corrosion ratio, steel tube section, steel tube thickness, and steel strength on the failure mode, bearing capacity, ductility, and confinement effect. The results demonstrated that increased corrosion ratio led to more pronounced local buckling of the external steel tube, resulting in decreased bearing capacity and ductility. Corrosion significantly weakened the CFHST specimens' bearing capacity compared to those with normal-strength steel tubes. Five methods were employed to establish a finite element model of the corroded CFHST columns, among which the method incorporating random pitting damage and the original strength of the steel proved to be the most reasonable. A parametric analysis was conducted to explore the impact of random pitting damage on the bearing capacity of the CFHST columns. Additionally, a comparison of the methods for calculating the peak bearing capacity of axial compression according to various codes indicated that all current codes were conservative. Consequently, a more precise calculating method was proposed to forecast the peak bearing capacity of corroded CFHST columns under axial compression.