Tension Stiffening Concept Based on Bond Slip

Consideration of tension stiffening in reinforced concrete panels by means of so-called “tension stiffening factors,” appearing in total and incremental equilibrium equations, has proved to be very effective. These factors result from bond slip between the reinforcement and the surrounding concrete. They are directly proportional to the average bond stress between adjacent cracks, the crack spacing, the cosine of the angle enclosed by the normal to the crack, and the reinforcement and inversely proportional to the average steel stress and the diameter of the reinforcement. The proposed concept does not require introduction of relative displacements. The method is applied to predict the short-term behavior of panels. The Finite Element Method is used as an analysis tool. Results agree well with experimental values obtained by other researchers. If, however, tension stiffening is disregarded, failure loads are underestimated whereas steel stresses are overestimated.