Design of thin-walled centrifugal concrete-filled steel tubes under torsion

The paper addresses the design of thin-walled centrifugal concrete-filled steel tubes under torsion. An experimental research project was conducted to study the behaviour of thin-walled centrifugal concrete-filled steel tubes under torsion. To further study the structural behaviour of the tubes thoroughly, finite element analyses were performed using ANSYS. The nonlinear finite element model was developed and verified against experimental results. Parametric study was conducted to investigate the effects of different concrete strengths, steel strengths and cross-section geometries on the strength and behaviour of thin-walled centrifugal concrete-filled steel tubes under torsion. The use of high strength steel in thin-walled centrifugal concrete-filled steel tubes under torsion was also investigated. The specimen strengths predicted from the finite element analysis were compared with the design strengths calculated using the AISC and ACI standards. It is also shown design strengths predicted by standards are very conservative. Design method is also proposed based on current standards. It is also shown that design strengths predicted using the proposed method agree with the numerical results well.