Numerical study of circular double-skin concrete-filled aluminum tubular stub columns

The sandwiched concrete in a circular double-skin concrete-filled aluminum tubular (DCFAT) column is subjected to the lateral confinement from inner and outer aluminum tubes. The effects of double-skin confinement have not been considered in the existing numerical models for the analysis of DCFAT stub columns. This paper describes a numerical model for the simulation of concentrically compressed circular DCFAT short columns. The numerical model is developed using the fiber element methodology. A new expression for determining the lateral confining pressures on the sandwiched concrete in circular DCFAT stub columns is proposed based on experimental results and incorporated in the computational technique. The stress-strain relations for determining the material performance of aluminum and confined sandwiched concrete are described. The numerical model is validated through comparisons with the experimental results of circular DCFAT stub columns. The numerical predictions correlate well with the tested column results, especially the aluminum stress-strain responses, load-strain responses, and ultimate axial load. A parametric study is performed to ascertain the influences of geometric and material variables on the behavior of DCFAT stub columns. The numerical results reveal that the use of aluminum instead of steel in a composite column could reduce the column weight by about 22.5%. The comparison of experimental results with the ultimate loads obtained by the design approaches specified in AISC 360-16, Eurocode 4, and Liang's design model indicates that the codified methods generally either underestimate or overestimate the strengths of DCFAT columns, and Liang's design model gives accurate predictions.