Research on the shear multiaxial performance and meso-mechanical mechanism of concrete

Abstract

Concrete structures are frequently subjected to multi-axial shear loading in practical engineering applications. Addressed the lack of clarity in the motivation for researching on the multi-axial mechanical properties of concrete in shear, this paper aimed to explore the shear multiaxial performance and failure mechanism of concrete by conducting composite compression-shear tests on concrete specimens with three strength grades (C30, C40 and C50) under different axial compression ratios using a compression-shear hydraulic servo machine. The test results indicate that there are significant differences in the failure behavior of concrete as the axial compression ratio increases, with both the shear strength and residual strength exhibiting an approximately linear increasing trend. Specifically, the shear strength corresponding to the three strength grades under various axial compression ratios increased by 135–343%, 147–349% and 137–351%, respectively, compared to the pure shear state. Based on such results, failure criteria for the shear strength of concrete under compression-shear action were proposed. Then, the entire crack evolution process during compression-shear was obtained using the digital image correlation (DIC) technology, and compression-shear performance of concrete was numerically simulated using the discrete element method (DEM). Finally, the compression-shear failure mechanism under different axial compression ratios was elucidated at the meso-level through analysis of the meso-mechanical behavior and crack development inside the concrete specimen. The findings of this paper provide a theoretical basis for the application of concrete materials in practical engineering.