Simplified equations for determining double-K fracture parameters of concrete for 3-point bending test

The paper presents simplified polynomial equations for determining the double-K fracture parameters of concrete for 3-point bending beams with variable strengths and material properties of concrete. The derived equations avoid complexities involved in computations of fracture parameters using existing analytical methods. The input data required for systematic computation in the study for deriving the nondimensional fracture parameters are obtained using a fictitious crack model. It is inferred that for a relative size of initial crack length, critical load and corresponding crack opening displacement maintain a linear relationship in their nondimensional forms. The value of critical mouth opening displacement can also be determined for known value of peak load using the derived nondimensional equation, thus avoiding the measurement of the crack mouth opening displacement in the experiment. Further, the derived polynomial equations predict the double-K fracture parameters of concrete with negligible error as compared to those obtained based on experimental results.