An Approach for Plastic Hinge Length of RC Columns

The exact determination of plastic hinge length (PL) is critical in estimating the nonlinear behavior of structural components. However, due to the complexity of material nonlinearity, previous attempts to define and model plastic hinge length have resulted in large discrepancies. This paper presents a comprehensive approach to estimating plastic hinge length based on several criteria, including rebar strain profiles, compressive strain of concrete core and cover, curvature profiles, and damage observations. The approach was validated through testing on three large-scale reinforced concrete (RC) columns subjected to high axial load ratios and varying transverse reinforcement details. Results showed that different criteria must be used to separate plastic hinge lengths (PLs) due to large discrepancies, and that high compression loads can enhance PLs due to compressive yield strain of longitudinal reinforcement, compressive strain of concrete, and curvature profiles, but have a minor effect on PL based on tensile yield strain. The amount of transverse reinforcement had an insignificant effect on PL. This study establishes important discussions on the PL of tested columns.