Nonlinear Modeling of Reinforced Concrete Columns under Cyclic Loading

Nonlinear modeling parameters for reinforced concrete (RC) columns under cyclic loading were investigated with an emphasis on failure mode and hysteretic energy dissipation. By reviewing existing shear and axial strength models, a failure mode-based modeling method to define the force-deformation relations was developed. The effective stiffness, yield deformation, and ultimate deformation to define the envelope relation were proposed as functions of axial compression ratio, shear span ratio, and the shear strengths of concrete and transverse reinforcement. Furthermore, the energy dissipation ratio (κ), defined as the ratio of the hysteretic energies dissipated by the actual behavior and idealized elastic-perfectly plastic behavior, was formulated, and the cyclic relation including hysteresis loops and unloading/reloading stiffness was defined using κ. For verification, the modeling results of load-deformation relations were compared with existing test results of columns under cyclic loading. Based on the investigation results, recommendations for the practical application of the proposed method were discussed.