The Experimental Comparison of the Uniaxial and Biaxial Flexural Tensile Strengths According to the Size of Specimens

This paper compared the results of experimental test of the biaxial flexural tensile strength of concretes to that of the uniaxial flexural strength according to the size of specimens. The uniaxial and biaxial flexural strengths in this study were obtained from the classical modulus of rupture (MOR) test and the biaxial flexural test (BFT) recently developed by Zi and Oh. We estimated load-strain relationship on the bottom surface of BFT specimens and three different sizes were considered to investigate the effect of the size of specimens. The average biaxial flexural tensile strength was greater than the classical modulus of rupture test. However, at the same time, the stochastic deviation of the biaxial test was greater than the modulus of rupture test. The load- strain relationships of two strain gages placed in the bottom surface of specimens is almost identical.