The rotation capacity of plastic hinges in reinforced concrete beams and slabs

Abstract

A mathematical model for calculating the rotation capacity of plastic hinges in reinforced concrete beams and slabs is presented. The model is based on the integration of the section curvature along the beam, taking into account the contribution of concrete between cracks (tension stiffening) and the shifting of the tensile force by shear cracks. The material behavior of reinforcing bars, concrete and bond is described as realistically as possible. The analytically predicted rotation capacities of about 70 beams compare favourably with the experimental results. The parameter studies demonstrate that the plastic rotation capacity of hinges given by the CEB-FIP Model Code is unconservative for cold worked deformed reinforcing bars with a low ratio tensile strength to yield stress and a low value of the uniform elongation.