Effect of Uniaxial Strength and Fracture Parameters of Concrete on Its Biaxial Compressive Strength

Abstract

The biaxial compressive behavior of concrete has been widely studied in the literature, and the biaxial envelope has always been reported for a particular uniaxial compressive strength. However, there is no theoretical or experimental evidence that concrete with similar strength exhibits similar biaxial behavior. In this study, several kinds of concrete with different maximum aggregate sizes were tested for their biaxial compressive strength under several load ratios. To ensure a uniform stress state in the cubic specimens, four layers of plastic membrane separated by three layers of butter were inserted between the steel loading platens and concrete surfaces to reduce the end friction during the test. In addition to biaxial strength, the uniaxial compressive strength, fracture energy, and characteristic length of each concrete mix were also determined. It was found that the biaxial compressive strength of concrete was dependent on both the uniaxial strength and the fracture energy (or characteristic length). Biaxial tests on concrete should therefore be conducted together with fracture tests to enable the proper comparison of biaxial behavior among different kinds of concrete. While further testing is required, this finding casts new light on concrete behavior under biaxial loading.