Investigation of behavior of concrete-filled double skin corrugated steel columns under axial and cyclic loading using finite element method

In this thesis, the structural behavior of concrete-filled double-skin corrugated steel composite columns under cyclic loading was investigated using the finite element method. The main objective of the study is to evaluate the effects of corrugated steel tubes on the load-carrying capacity, ductility, and energy absorption capacity of the columns. Within this scope, composite column specimens were modelled using three configurations with different cross-sectional geometries. These configurations consist of columns with a corrugated inner steel plate and a flat outer steel plate, columns with a corrugated outer steel plate and a flat inner steel plate, and reference columns with both flat inner and outer steel plates. Moreover, the effects of steel wall thickness and column slenderness on the structural behaviour were investigated. Material properties were kept constant in all models. According to the analysis results, the columns with a corrugated cross-sectional geometry exhibited higher load-carrying capacity and more stable load-displacement behaviour compared to columns with flat plates. Furthermore, the study indicated that the outer corrugation design provided better confinement to the concrete core, delayed local buckling, and thus achieved an average of three times more energy absorption capacity compared to the reference column and one and a half times more compared to internally corrugated columns. Increasing the steel wall thickness resulted in significant improvements in both ultimate capacity and energy dissipation. Overall, this study reveals that the geometry of double-skin steel sections, especially those with a corrugated outer surface, is beneficial and can be advantageous for structures in highrisk earthquake zones.