Lu Dechun

Nonlinear multiaxial dynamic strength criterion for concrete material

Basic strength parameters of concrete material which are uniaxial compressive strength, uniaxial tensile strength, biaxial compressive strength and biaxial tensile strength are used to replace the four material parameters of generalized nonlinear strength theory in this study. The change rules and value ranges of four material parameters are acquired by studying the basic strength characteristics of concrete materials. Nonlinear multiaxial dynamic strength criterion for concrete material is proposed by four rate effect expressions of basic strength parameters for concrete material, and the four rate effect expressions are established on the basis of S criterion. The rate effect rules of dynamic strength parameters express that with the increase of strain rate, strength properties of concrete gradually transform to that of metal material. Dynamic strength of concrete is significantly influenced by the strain rate in the range of -3 to 3, and dynamic strength does not increase indefinitely, instead, there is a peak dynamic strength. Compared with dynamic loading test of biaxial compressive-compressive and biaxial tensile-compressive of concrete, nonlinear multiaxial dynamic strength criterion can describe the biaxial dynamic strength rule of concrete reasonably and the nonlinear strength characteristics at a certain strain rate. Strength rules are not influenced by coupling between the strain rate effect and multiaxial stress state, in other words, the dynamic strength surfaces dose not intersect at different strain rates.