Behavior of thin-walled dodecagonal section double skin concrete-filled steel tubes under bending

• Beam tests of dodecagonal section double skin concrete-filled steel tubes were presented in this study.
• The bending behavior of test specimens were obtained.
• The local buckling of dodecagonal section double skin concrete-filled steel tubes was investigated.
• Parametric study was carried out using the verified finite element model.
• The suitability of different design equations was evaluated.

The behavior of thin-walled dodecagonal section double skin concrete-filled steel tubes under bending was studied in this paper. Both experimental investigation and finite element analysis (FEA) were carried out. A total of 7 specimens were tested with the beam length of 2000 mm. The width to thickness ratio of the outer steel tube ranged from 75 to 133. The load–displacement curves, failure mode and ultimate capacity of test specimens were obtained. A finite element model was developed for the thin-walled dodecagonal section double skin concrete-filled steel tube subjected to bending. The FEA results were verified against the test results and parametric study was conducted using the verified model. In addition, the suitability of Han's method, Uenaka's method and proposed method for thin-walled circular section double skin concrete-filled steel tubes subjected to bending was also evaluated.