Investigation of the behaviour of concrete-filled stainless steel tubular composite columns

In the presented study, experimental and theoretical behaviour of concrete-filled stainless steel tube composite columns subjected to biaxial bending and axial compression are examined. In the study, ten concrete-filled stainless steel tube composite columns were prepared. Column specimens were constructed with plain and steel fiber concrete, I-shaped and T-shaped carbon steel were embedded into the tube section. The prepared test specimens were tested under biaxial bending and axial compression. In the comprehension of experimental study, ultimate load and load-deflection curves of concrete-filled stainless steel tube composite columns were obtained. In the experimental work, it is revealed that steel fibers had favourable effect on column deformation capacity. It is determined that the structural steel embedded in tube section prevented column buckling. In this research, ductile behaviour was observed for the tested concrete-filled stainless steel tube composite column specimens. In addition, a theoretical method was suggested for the analysis of concrete-filled stainless steel tube composite columns in the study. Nonlinear behaviour of the materials was taken into account in the analysis. In the procedure, concrete compression zone, stainless steel tube section and carbon steel section were divided into segments. The strain values were calculated in the center of each segment. Then, the stresses were attained from the materials' stress-strain relationships using calculated strain values. Thus, the column strength capacity and load-deflection values were obtained from the solution of equilibrium equations written in terms of stresses. The tested columns were analysed based on the proposed theoretical method. In the analysis, the theoretical ultimate strengths and load-deflection curves were obtained in good agreement with the experimental results. The structural behaviour of the tested columns were determined in the study.