Fracture and Failure of Concrete in Uniaxial and Biaxial Loading

General analytical equations are developed to predict the overall failure stresses for plain concrete subjected to biaxial stresses. Specifically, failure equations are derived for uniaxial tension, uniaxial compression, biaxial tension, biaxial compression‐tension, and biaxial compression. The general framework of the proposed model is based on the actual events that occur in the material during loading. According to previous experimental investigations, internal microcracks exist in the concrete prior to the application of any external loading. It is shown that the growth and interaction of these preexisting microcracks in the mesostructure of the concrete eventually cause the macroscopic failure of the specimen. Only experimental parameters (concrete mix proportions and coarse aggregate sieve gradation) are required to predict any of the failure stresses. The results generated from the models compare favorably to the experimental data for all loading cases, even though the formulation is not adorned with any unidentifiable constants or parameters.