Tension Stiffening Model for Planar Reinforced Concrete members

Abstract

Presented in this paper is a tension stiffening model capable of describing the final cracking point and steel yielding in cracked faces observed in typical behaviors of reinforced concrete members. In this model, average stress-strain relationships of concrete in the post-cracking range, including these two control points, can be obtained by means of a tension stiffening factor, which is related to the transfer length, the average crack spacing and the distribution function of concrete stress. The parameters of the problem are determined by solving the differential equation based on the bond stress-slip relationship. Consideration of the tension stiffening effect in the direction of a steel bar makes it possible to extend the proposed model to planar reinforced concrete members. This model is implemented in an orthotropic rotating-crack model considering the expansion and confinement of concrete. The predictions of the average stress-strain relationships of concrete, including the final cracking points from the proposed model are satisfactory when compared with available experimental data. The model is also successfully applied to FE analysis of panels loaded biaxially.