Presliding Shear Failure in Prestressed RC Beams. II: Behavior

Abstract

In the companion paper, based on the theories of partial interaction and shear friction, a mechanics-based segmental approach, which can cope with any cross section and material property, was developed to simulate the shear behavior and failure of prestressed concrete beams with and without stirrups. The included equations and mechanisms are purely mechanics-based and independent of empirical material properties. In this paper, this numerical approach has been applied to describe the shear behavior of prestressed RC members. The effect of prestress on the shear behavior is explained, and the results of parametric studies on stirrup effectiveness are also shown. Published test beams with and without stirrups, 102 of them, have been analyzed by the proposed model and analytical results show good agreement with the experimental data. The average predicted results for the beams without stirrups being 96% of the test results and that for the beams with stirrups being 91% with coefficients of variation of 0.10 and 0.08, respectively. The equations provided by the ACI standard have been used to calculate the shear strength of the same test specimens, and the ACI shear provisions are shown to be quite conservative with an average of 67 and 74% and coefficients of variation of 0.29 and 0.18 for beams with and without stirrups. The influence of the random nature of cracks on the shear strength is also investigated.