Static–Dynamic Universal Strength Criterion for Concrete Material

Studies on the biaxial strength criterion provide a significant theoretical basis for the exploration of concrete material’s biaxial and multiaxial mechanical properties. In this study, mesoscopic modeling of concrete cube specimens with an average compressive strength of 30 MPa was established. Numerical experiments were performed under dynamic biaxial conditions with different strain rates (research scope: ${10}^{-5}{\mathrm{s}}^{-1}–1{\mathrm{s}}^{-1}$) and lateral stress ratios (research scope: 0–1 in biaxial compression loads and $-1–0$ in biaxial tension–compression loads). The effects of strain rate and lateral stress ratio on the dynamic biaxial strength of concrete were studied. Based on multi-parameter analysis, a universal static-dynamic biaxial strength criterion of concrete material was established. The proposed strength criterion breaks through the limitations of traditional physical test conditions and provides a higher application range for strain rate (${10}^{-5}{\mathrm{s}}^{-1}–1{\mathrm{s}}^{-1}$) and lateral stress ratio. In addition, the proposed criterion has a more concise expression, which is more convenient for engineering applications. Moreover, the influence of various parameters on concrete strength was considered and coupled. Finally, the accuracy and applicability of the established strength criterion were verified by comparing the predicted dynamic biaxial compressive strengths under different loading conditions with four sets of experimental results. The comparisons indicate that the predicted strength criterion surface agrees with test results for a wide range of loading conditions from biaxial compression to biaxial tension–compression. The dynamic strength criterion provides new insights for concrete mechanical investigation and engineering structure designing.