Torsional Behavior Of High-strength Reinforced Concrete Columns Under Combined Force

Torsion problems came to stand out in the project with the development of high-rise buildings and complex structures, the application of high-strength reinforced concrete was received more attention by people. It is necessary to make deeper study on composite torsion of high-strength reinforced concrete members under compression, bending and shear. At present, the study in biaxial eccentric compression, bending, shear and reversed torque of reinforced concrete is not enough over the academic circles, therefore, this subject is of profound theoretical and practical significance.Finite element analysis software ANSYS was used to simulate the specimens of a test in this paper. It analyzed the elastoplasticity performance of the concrete members under compression, bending, shear and torque through the establishment of the finite element model. Besides, the composite torsion behavior was deeply studied by considering various factors, including cracking torque, torsion bearing capacity, hysteretic property, ductility and energy-dissipation property of concrete members under composite torsion. The main contents of this paper can be summarized as follows:(1) By using finite element analysis software ANSYS, concrete members subjected to humdrum torque H4-4 and reversed torque HR3-2 under eccentric compression, bending and shear of a test were simulated and calculated. The results of ANSYS was tallied with the experiment, the composite torsion behavior was well simulated by ANSYS.(2) By simulation of 12 high-strength concrete columns subjected to compression, bending, shear and humdrum torque, in the case of the same ratio of axial load to compression for 0.4 and relative eccentricity for 0.4, torsion performance was studied by difference value of concrete strength, the reinforcement ratio of longitudinal steel reinforcement and loading angle. The results show that the initial stiffness and ultimate torque increase with the improving of the value of concrete strength, the ductility decreases with the improving of the value of concrete strength.(3) By simulation of 9 high-strength concrete columns subjected to compression, bending, shear and reversed torque, in the case of the same ratio of axial load to compression for 0.4 and relative eccentricity for 0.4, torsion performance was studied by difference value of concrete strength and the reinforcement ratio of longitudinal steel reinforcement. The results show that the ultimate torque increases with the improving of the value of concrete strength, the ductility decreases with the improving of the value of concrete strength, the ultimate torque and ductility increase with the increase of the reinforcement ratio of longitudinal steel reinforcement, the retrograde tendency decreases under the same displacement loading when reaching the ultimate load, the degeneration factor increases with the increase of the reinforcement ratio of longitudinal steel reinforcement, and changes a little with the different value of concrete strength, the ductility decreases when the members subjected to reversed torque than humdrum torque.