Calibration of the Length of the Plastic Hinge for Numerical Models of Reinforced Concrete Members

A proper and computationally efficient numerical modeling of the nonlinear cyclic flexural behavior of reinforced concrete members is crucial for the assessment of the seismic response of RC framed structures. To mitigate the problem of damage localization and improve the stability of the numerical model, force beam column elements with fiber cross-section and finite length hinges located at the ends of the member are often used. In this case, the accuracy in the prediction of the cyclic response is strictly dependent on the length assigned to the plastic hinge. In the past, several authors have proposed formulations to evaluate this crucial parameter based on observations and data from laboratory tests. Nevertheless, the values given by these expressions can differ significantly from each other. In this paper, the optimal value for the length of the plastic hinge is calibrated by comparison between laboratory and numerical test results. Laboratory tests are selected to identify members that are representative of columns of existing reinforced concrete buildings. Based on the optimal values of the plastic hinge length found for the selected set of laboratory tests, a simple relation of the plastic hinge length has been proposed.