Compressive torsional hysteresis performance of concrete filled square CFRP steel tube

To study the mechanical performance of concrete-filled square CFRP steel tube under compressive-torsional hysteresis loads, 9 concrete-filled square CFRP steel tube to analyze the failure mode, torque angle curve, triaxial strain, and the synergistic effect of steel tube and CFRP on the specimen under cycle loading. The experimental results show that the steel tube and CFRP can work together. Based on the tests, a numerical simulation method is firstly proposed to estimate the concrete-filled CFRP steel tube compressive-torsional specimens under hysteresis loading, and then validated against the representative tests results. As the axial compression ratio increases(0 < n ≤ 0.45), the torsional displacement of the specimen is constrained, resulting in increase of bearing capacity By contrast, as n continuous increases, the initial stiffness of the component begins to decrease, and the bearing capacity also decreases when n > 0.45. In addition, the increase in steel content, CFRP layer, and specimen material strength has a significant impact on the bearing capacity and initial stiffness.