Numerical study on behavior of eccentrically loaded concrete-filled bimetallic tubes

The concrete-filled bimetallic tubular (CFBT) member studied in this paper comprises a stainless steel/carbon steel bimetallic tube infilled with core concrete. It has the advantages of enhanced mechanical property, good corrosion resistance and cost effectiveness. A finite element analysis (FEA) model is established to investigate the performance of eccentrically compressed CFBT short columns with a circular cross-section. The model is verified against the experimental results presented in a companion paper. The comparisons show that the FEA model reproduces reasonably well the failure mode, load-deformation response, ultimate strength and strain development of the composite member. The validated model is then used to further investigate the performance of eccentrically loaded CFBT members, followed by a wide-range parametric analysis. Results indicate that the two layers of the bimetallic tube attain their ultimate strength before the concrete core. The material strength shows a major effect on the ultimate strength of CFBT members, whilst the coefficient of friction for the interface between different materials and the strain-hardening exponent of stainless steel have a minor influence. Finally, the applicability of various design codes is explored and the comparisons show that the load-carrying capacity predicted by AISC360-16 is conservative, whilst Eurocode 4 and DBJ/T13-51-2010 produce relatively accurate predictions.