| High strength and normal strength reinforced concrete beams were tested at early ages and at maturity to evaluate their performance in shear. Tests conducted by other researchers suggested that the ACI code equation for shear in concrete, Vc, overstates the shear capacity of high strength concrete members. Tests by other researchers suggested that members subjected to early age loading failed in shear instead of flexure.; The results of the beam tests conducted here suggest that whether or not shear failure of high strength concrete members occur at loads less than that predicted by the ACI code equation appears to depend, in part, on the definition of shear failure being used. This appears to apply for members loaded at early ages and at maturity.; A performance base definition of shear and a model for predicting shear capacity that is based on this definition is also presented here. The model is based on principles of statics, however, it uses the tensile properties of the concrete in a strain energy format. The model's failure state is based on crack opening. |
