Compression–bending resistance of corrugated steel tube‐confined rubberized concrete columns considering non‐uniform confinement

Corrugated steel tube‐confined rubberized concrete (RuCFCST) columns are a promising composite system for seismic‐resistant structures because they combine the confinement efficiency of corrugated steel tubes (CSTs) with the enhanced deformability of rubberized concrete. Under lateral or seismic actions, these columns are commonly subjected to combined axial compression and bending. However, the non‐uniform confinement mechanism of CSTs and its incorporation into compression‐bending design remain insufficiently understood. This study develops a refined finite element model for RuCFCST columns under eccentric compression by incorporating the confinement‐sensitive damage plasticity of rubberized concrete, the nonlinear behavior of cold‐formed CSTs, and the interface interaction between the CST and core concrete. The model is validated against previous tests in terms of load–displacement response, failure mode, and strain development. A parametric study is then conducted to examine the effects of eccentricity, corrugation profile, spiral angle, CST yield strength, rubberized concrete strength, and diameter‐to‐thickness ratio. The results show that the corrugated geometry promotes axial‐to‐hoop stress redistribution in the CST, producing spatially non‐uniform confinement with distinct crest–waist–trough stress variations. Based on this mechanism, an equivalent confinement stress model is proposed to convert local confinement into a design‐oriented parameter. Finally, a simplified compression‐bending resistance model and corresponding N – M interaction relationship are developed. The proposed framework links CST‐induced non‐uniform confinement to sectional resistance design of RuCFCST columns.