A simplified numerical simulation of circular CFDST short column with NC, HPC and UHPC under compression

In this study, axisymmetric models to predict the ultimate strength of circular concrete-filled double-skin steel tube (CFDST) short columns containing Normal Concrete (NC), High-Performance Concrete (HPC), or Ultra-High-Performance Concrete (UHPC) under axial compression are developed. A simplified concrete material model is proposed for these axisymmetric models, offering more convenience compared to the previous axisymmetric model, which was validated only for NC, HPC, and concrete-filled steel tube (CFST) columns. The reliability and accuracy of the new model are verified using experimental data. This study demonstrates that the combination of the axisymmetric model and the simplified concrete model significantly reduces computational time while maintaining acceptable accuracy. The proposed method can generate extensive numerical databases for structural optimization or machine learning-based strength prediction. The reduced computational effort of axisymmetric models, compared to 3D models, allows for a comprehensive parametric study of axial load-displacement curves in circular CFDST short columns, exploring various influencing factors. Additionally, the study evaluates established design codes, including Eurocode 4 (EC4), American Concrete Institute (ACI), and American Institute of Steel Construction (AISC), along with analytical models from the literature, thereby enhancing the understanding of circular CFDST short columns under compression.