Three-Dimensional Cyclic Behavior Simulation of RC Columns under Combined Flexural Moment and Torsion Coupled with Axial and Shear Forces

Abstract

Full three-dimensional nonlinear finite element analysis based on the path-dependent non-orthogonal multi-directional crack model is applied to RC columns subjected to combined cyclic flexure/shear and torsion. This loading causes non-orthogonal crack-to-crack mechanistic interactions accompanying opening/closure and shear slip along crack planes. The analytical results show that the proposed methodology is able to simulate the highly nonlinear behavior of RC columns under cyclic loading, including not only load-carrying capacity but also complex restoring force characteristics and post-peak softening after peak strength. Sensitivity analysis is also carried out to examine the effectiveness of the transverse reinforcement, which simultaneously resists both transverse shear and torque moment. The current design procedure for determining the necessary and sufficient amount of web reinforcement is reviewed and the necessity of performance assessment is raised.