Structural behavior of concrete-filled steel tubular (CFST) with spherical cap gap subjected to corrosion and long-term tensile loading

College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fujian 350108, China

^* Corresponding author: feiyu.liao@fafu.edu.cn

Abstract

Concrete-filled steel tubes (CFSTs) are commonly used as structural specimens in construction. Gaps between the steel tube and enclosed concrete core can form during manufacture or repair procedures. This study developed a computational model to investigate the structural implications of spherical cap gaps in CFSTs subjected to sustained axial tension and chloride-induced corrosion. Finite element analysis (FEA) incorporated appropriate material constitutive laws and elements. Model predictions closely matched experiments for load-displacement response and ultimate capacity. Parametric comparisons between gap and no-gap geometries quantified performance impacts, including reduced stiffness, deteriorated load transfer, internal force redistribution, and diminished flexibility stemming from localized steel tube buckling adjacent to the unrestrained gap. Outcomes highlight the importance of quality control during CFST production and repair to minimize defects like uncoupled zones between the concrete infill and hollow tube. The validated simulation approach provides an efficient tool for exploring gap influences and informing structural design provisions.