Tension-stiffening model attributed to tensile reinforcement for concrete flexural members

Abstract

Adequate modeling of reinforced concrete (RC) cracking and, particularly, post-cracking behavior (tension-stiffening), as one of the major sources of a nonlinearity, is the most important and difficult task of the deformation analysis. Present investigation aims at deriving a steel-related tension-stiffening relationship based on the smeared crack approach. The analysis uses the results of the experimental program performed by the authors. It consisted of three beams reinforced with three deformed bars of 18, 14 and 10 mm in diameter. Other characteristics of the beams were almost identical. An inverse technique has been developed to derive a steel-related tension-stiffening model from the moment-curvature diagrams of the beams. The constitutive relationship recommended by Eurocode 2 was assumed for the compressive concrete, whereas the elastic-brittle behavior was taken for the concrete in tension. The tensionstiffening effect was modeled by the stress-strain relationship of the tensile reinforcement. For the model assumed, total stresses in the tensile reinforcement consist of genuine stresses corresponding to the average strain of the steel and the additional stresses due to tension-stiffening. It was found that the tension-stiffening stresses, normalized in regard to reinforcement area, have become almost independent on the amount of reinforcement. The proposed technique is capable of investigating the tension-stiffening behavior in RC flexural members.