Post‐Cracking Behavior of Membrane Reinforced Concrete Elements Including Tension‐Stiffening

The objective of this study is to develop a unified model for the postcracking behavior of a reinforced concrete element under tension‐compression. Such a model would consider the steel‐concrete interface interaction, the concrete compression‐tension failure interaction, and the constitutive properties of the materials. The model would unify the major concepts underlying the limit‐state design models, analysis models, and the phenomenological models developed to simulate test results. The present paper presents the first part of the study, a post‐cracking model that includes the tension‐stiffness effect by considering the steel‐concrete interface interaction. Reinforcing bars transfer tensile stresses to the concrete through bond stresses at the steel‐concrete interface. It is assumed that the bond stress‐slip relationship remains linear. The formulation leads to a strain‐stress relationship for the reinforced concrete element including the tension‐stiffness effect. Expressions in the relationship are quite complex, which are greatly simplified when the Poisson ratio is zero. The complete unified theory and its application are given in a companion paper.