عنوان مقاله [English]
Concrete-filled steel pipes (CFSTs) are increasingly used in the construction industry due to their high bearing capacity, high ductility and energy dissipation capacity, as well as high toughness and toughness under cyclic loads compared to conventional hollow steel pipes. Have become common. In this research, numerical evaluation of cyclic behavior of steel columns filled with concrete polygon sections is the main direction of the article. The research method of this study was based on finite components using Abaqus software. For the accuracy of the numerical responses, a numerical sample was simulated in accordance with the laboratory sample and the results were validated. In the next step, parametric study was performed on the cyclic behavior of steel columns filled with polygon sections. The geometrical parameters of column cross section, steel wall thickness, concrete compressive strength and axial force ratio were investigated. The geometrical shape of the cross sections was 4, 6, 8, and 12 rectangular and circular. Steel wall thicknesses of 3, 4 and 5 mm, compressive strength of concrete 20, 30 and 40 MPa and axial force ratio above the column are considered 0.1, 0.3 and 0.5. Loading into concrete filled steel columns with two polygon sections was done in two stages, first in axial pressure load and in the second stage in cyclic load as control-displacement. The results showed that the geometric shape parameter of the column cross section when changing from circle to rectangle causes maximum increment of indices of stiffness, force the yield, ultimate strength, ductility and energy are 37%, 36%, 32%, 64% and 71%, respectively. The ratio of the axial force applied to the structure to the maximum lateral load utilization with respect to the values of 0.3 is recommended and the cross section geometry index has the greatest impact on the strength, ductility and energy dissipation without any change.