Study on behavior of Concrete Filled Double Skin Steel Tubular Under Torsion and Cyclic Loading

Concrete- Filled Double Skin Steel Tubular (CFDST) columns are members of the Concrete- Filled Steel Tubular columns (CFST) family. In CFDST the steel skin and the existing concrete affect each other behavior so that the concrete prevents buckling of the inner and outer steel skins and the both steel skins under load result in the development of the confinement force and subsequently increase the ductility of the concrete and prevent the concrete from brittle damage. To ensure the accuracy of the finite element modeling, the experimental results were compared with the finite element and the accuracy of the modeling was verified. In this research, the section geometry, under monotonic and cyclic loading was investigated. The out-come results show that the CFDST columns have a good ductility, higher energy absorption capacity during an earthquake event and improved behavior under cyclic loading in comparison with CFST columns