Compressive Behavior of Slender Discontinuous Double Steel Tube Confined Concrete Column Under Concentric Loading

This paper numerically investigates the compressive behavior of a new form of Double Steel Tube Confined Concrete (DSTCC) column where the inner Concrete-Filled Steel Tube (CFST) is confined by a discontinuous steel tube and a sandwiched concrete core. In this configuration, the discontinuous steel tube will not carry any axial load directly rather it is supposed to provide adequate confinement to the CFST column. In addition, due to the discontinuity of the outer steel tube, the occurrence of the local buckling near the supports could be prevented. Thus, the axial load-carrying capacity of the proposed Discontinuous Double Steel Tube Confined Concrete (DDSTCC) column would be enhanced as compared to the conventional (DSTCC) column. Till date, very little attention has been paid to investigate the compressive behavior of this type of column. Thus, the aim of this study is to develop a comprehensive finite element (FE) model in ABAQUS by considering both geometric and material nonlinearities to investigate the compressive behavior of slender DDSTCC columns under concentric loading. The developed FE model was first validated against the existing test results and then it was adopted to carry out a parametric study to investigate the effect of various key parameters on the compressive behavior of the DDSTCC column which includes thickness of outer and inner steel tubes, different grades of concrete. It can be observed that the concrete's compressive strength has significant influence on the ultimate load, whereas the thickness of the steel tube contributes to residual load carrying capacity of the column.