A Novel Three-Dimensional Modified Griffith Failure Criterion for Concrete

This study proposes a three-dimensional failure criterion based on the Griffith criterion, which accounts for the nonlinear influences of hydrostatic pressure and Lode angle on the failure strength of concrete. Two approaches are utilized in the proposed criterion to describe the Lodedependence, one is to use the biaxial compressive envelopes to derive each meridian directly, and the other is to employ a scaling function between the compressive and tensile meridians. Besides, the proposed criterion can be expressed by the principal stresses in the form of f(51, 52, 53) = 0 as well as by the stress invariants in the form of J2 = f(P, theta). To comprehensively validate the proposed criterion, it collects 37 groups of tests with nearly 1000 test data conducted on concrete under biaxial and triaxial stress states. It demonstrates that predictions of the proposed criterion, including biaxial failure envelope, compressive meridian, tensile meridian, deviatoric section, and multiaxial strength, are close to the corresponding experimental observations. The proposed criterion requires four parameters, three of which have clear physical meaning, namely the tensile, compressive, and equal-biaxial compressive strength (ft, fc, and fbc), and the rest parameter n can be determined by the triaxial compressive strength. Aimed at elaborating the physical meaning of n, it interprets the proposed criterion as a combination of the original Griffith, MohrCoulomb, and Rankine criteria. In addition, a simple modification based on the proposed criterion is also suggested to describe the transformation from shear failure to ductile failure of concrete with the increase of pressure. Compared with the existing Ottosen and Willam-Warnke criteria, the proposed criterion is simple in determining parameters, convenient in the application, and diverse in describing the Lode-dependence.