Static–Dynamic Combined Multiaxial Strength Criterion for Concrete.

The physical mechanism of the static–dynamic combined (S–DC) multiaxial strength of concrete is investigated considering cohesive and frictional strength. It is determined that the strain rate effects and stress state effects on the shear strength of concrete can be decoupled. An effective initial static stress is defined to distinguish the part of the cohesive strength that is dependent on the strain rate; the other part is consumed by the initial static stress. Furthermore, the strength parameter, which reflects the coupled effects of the initial static stress and the strain rate on the strength, is obtained based on the effective initial static stress and dynamic increase factor (DIF). Combining the proposed strength parameter and nonlinear dynamic multiaxial strength criterion, a new S–DC multiaxial strength criterion for concrete is presented. The proposed strength criterion is applied to analyze the S–DC strength rules of concrete under multiaxial stress conditions and is further verified using five groups of test results. [ABSTRACT FROM AUTHOR]