Axial compression behavior and reliable design approach of rectangular dune sand concrete-filled steel tube stub columns

Concrete-filled steel tube (CFST) columns, incorporating various types of concrete, are increasingly prevalent in engineering applications. This study develops a finite element (FE) model and a design methodology for rectangular dune sand-concrete-filled steel tube (DS-CFST) columns. Investigating the composite behavior of rectangular DS-CFST columns and the effects of different DS replacement ratios, the results indicate a reduction in the ultimate bearing capacity compared to traditional CFST columns, attributed to diminished confinement effects, particularly at higher DS replacement ratios. Analysis of different design factors, including concrete and steel strengths, steel ratio, and aspect ratio, assesses their impacts on axial load-bearing capacity and composite behavior. This analysis leads to the establishment of a design formula, validated through experiments and FE analysis. The formula's efficacy and conciseness are evaluated against current design codes, with a reliability study assessing sensitivity to fluctuations. The proposed formula demonstrates accurate predictions of the ultimate load-bearing capacity.