Experimental and finite element method investigation of concrete filled circular steel tube sections

In this study, a total of 70 test specimens, consisting of 56 concrete-filled composite columns of circular cross section and 14 hollow steel tubes with various geometric and material properties, were tested under axial loading. In the experimental study; four different concrete compressive strength, three different diameter/wall thickness (D/t) ratios, and seven different height/diameter (L/D) ratio parameters were taken into account. The ultimate axial force, vertical displacement, and failure modes of the concrete filled composite columns obtained from the test results were calculated. Concrete contribution Ratio (CCR) index, strength index (SI), and ductility index (DI) were determined from the test results obtained. The ultimate axial force strengths of the specimens using ANSI/AISC 360-16 and Eurocode 4 were determined. The obtained values were compared with the experimental results. Finally, finite element models were created to predict the behavior of concrete filled composite columns under axial force. It was observed that the results obtained from the finite element models were 5% more than the experimental results.