Abstract
The concrete-filled double tubular steel column (CFDST) is a composite column that shows remarkable potential for the construction of tall buildings and bridge piers. When this type of column is exposed to external forces such as collisions with ships or cargo vehicles, explosions or fires, it loses strength. The outer steel tube of the column is affected, resulting in the loss of the concrete inclusion between the two layers of steel. As a consequence, a significant drop in column strength becomes evident. The aim of this study is to investigate the effects of cyclic loading on CFDST columns with a new reinforced circular cross-section, which have a constant number of stiffeners and stirrups over the entire column. Two specimens were subjected to constant axial compression and lateral cyclic loading to compare the behavior of a proposed reinforced cross-section (new reinforced cross-section) with that of a simple cross-section. The data from the test was used to validate a finite element analysis (FEA). Subsequently, the validated numerical models were used to evaluate the effects of various parameters, including the thickness of the pipes and the compressive strength of the concrete, on both cross-sections. In summary, the results show a significant improvement in the cyclic behavior of the column with a reinforced cross-section compared to a simple cross-section. The recommended reinforced cross-section thus prevents a sudden drop in column strength after the outer steel tube has been damaged.