MESO-SIMULATION ON DYNAMIC BIAXIAL COMPRESSIVE STRENGTH CRITERION OF CONCRETE

Due to the limitations of physical test equipment and conditions, the existing studies on dynamic biaxial compressive strength criteria of concrete only in the range of low strain rate (10⁻⁵ s⁻¹~10⁻² s⁻¹). To investigate whether these strength criteria are applicable at higher strain rates or not, a mesoscopic random aggregate model was established. The meso-simulation analysis of concrete cubic specimens with side length of 100 mm under dynamic biaxial compressive loads were carried out. The influence of strain rate and lateral stress ratio on dynamic biaxial compressive failure modes and compressive strengths of concrete were analyzed. A dynamic biaxial compressive strength criterion applicable to higher strain rate was established. The conclusions are as follows: Under the same lateral stress ratio, a higher strain rate leads to an increase in the internal damaged area and the dynamic compressive strength of concrete. Under the same strain rate, a higher lateral stress ratio causes the failure mode of concrete changes from cylindrical fracturing to sheet splitting and the dynamic compressive strength first increases and then decreases. The existing dynamic biaxial compressive strength criterion of concrete is inapplicable in 10⁻⁵ s⁻¹~1 s⁻¹, while the improved strength criterion proposed can be applied to a larger strain rate range, which has been preliminarily verified by various physical tests.