Study on Torsional Performance of Square Concrete Filled CFRP-Steel Tubes

The torsional performance of square concrete filled CFRP-steel tube (S-CF-CFRP-ST) is revealed by experimental study. Total 18 specimens, taking the confinement factor of transverse CFRP, strengthening factor of longitudinal CFRP and the compressive strength of cubic concrete as principal factors, were designed and tested under torsional load. Based on the tests, a numerical simulation method is firstly proposed to estimate the torsional performance of S-CF-CFRP-ST, and then validated against the representative tests results, such as the failure modes, torque-rotation angle curves. The good consistence between numerical results and experimental ones reveals that the proposed simulation method can predict the torsional performance of S-CF-CFRP-ST reasonably and accurately. Finally, according to both the experimental and numerical results, the torsional bearing capacity of S-CF-CFRP-ST is determined as the torque endured by specimen with maximum shear strain reaching 15,000 mu epsilon, together with its corresponding calculation formula.