Computer-aided investigation of the tensile behavior of concrete: Relationship between direct and splitting tensile strength

Currently, a standardised approach for testing the direct tensile strength (fdt) of concrete has yet to be established. Consequently, the correlation between the fdt and the splitting tensile strength (fst) of concrete holds significant importance in evaluating its uniaxial tensile strength. We first review the theoretical relationship between fdt and fst of concrete, then propose a 3D random mesoscale modelling approach to simulate its mechanical behavior under direct and splitting tensile stresses, covering various concrete strength classes (C30C50). Finally, we derive empirical formulas for the tensile strength and uniaxial compressive strength (fc) via regression analysis of available test data and simulation results, including fst vs. fc, fdt vs. fc, and fdt vs. fst. The findings suggest that the proposed 3D mesoscale model, which takes into account the random characteristics of aggregates such as their shape and distribution, is highly feasible for simulating the tensile behavior of concrete. Widening the load-bearing strip has been shown to enhance the splitting tensile strength, and both fdt and fst can be improved as the concrete strength grade increases. While linear elastic theory implies that the theoretical fdt surpasses fst, the empirical results indicate that the fdt is actually relatively smaller, ranging from 10% to 60% lower than the fst. Moreover, based on the synthesized test and numerical results, a significant power regression relationship has been established between the fst and fdt of concrete.