Finite Element Analysis of Concrete Filled Double Skin Steel Tubular Circular Column Subject to Axial Compression Loads

Abstract

Concrete filled double skin steel tubular circular (CFDSSTC) column is a creative innovation of steel-concrete composite construction, which are filled with concrete and supported by circular steel tubes on the interior and exterior. These steel tubes serve as formwork and hence these members are economical and quicker to construct when compared to conventional reinforced concrete columns. They are also efficient because they take advantage of the higher compressive strength of the concrete and high tensile strength of steel. CFDSSTC columns are proved to have good structural performance in terms of strength, stiffness, ductility and fire resistance. This paper represents circular structural inner and outer steel tube filled with self-compacting concrete. Concrete filled double skin steel tubular circular (CFDSSTC) columns were modeled non-linearly by finite element method and analyzed in order to investigate the axial compression behavior of the specimens. The model of CFDSSTC column consisted of 3D solid elements to represent the inner and outer steel, concrete and, thick plate shell element to model the whole specimens. The study proceeded by simulating of the model of the axial loads using Static, Riks non-linear finite element code. Different parametric studies were carried out. In the parametric studies, length of the column, hollowness ratio, internal and outer steel tubes thickness were taken as a parameter and the specimens were loaded in a concentric axial compression to investigate regarding their influence on the behavior of the columns. The result obtained from finite element analysis was carried out and verified with the experimental results obtained from the journal and used as a viable tool to expand the investigation into the axial behavior of CFDSSTC columns without having to conduct further expensive and time consuming tests. A parametric sensitivity analysis was performed using the validated finite element model to develop an in-depth understanding of the effects of various structure-related parameters on the impacts response of axially loaded CFDSSTC columns Finally, the modeled columns were analyzed on ABAQUS 6.14 and their load displacement diagrams were drawn. The ultimate axial load capacities of all the columns were determined from these non-linear load-displacement curves. The study show that as the length and hollowness ration increase, the load resisting capacity of the column was decreased and there is an improvement on the behavior and axial load carrying capacity of concrete filled double skin steel tubular circular column due to the change in thickness of outer and inner steel tube. The strength of the column increase by 2.52% - 8.73% and 4.84% - 12.27% when the thickness of inner and outer steel tube thickness change from 2mm to 4mm respectively.