Using numerical simulations to determine the accuracy of the size-effect and two-parameter data reduction methods for fracture toughness tests of concrete

The size-effect and two-parameter data reduction methods were developed to extract size independent parameters from fracture toughness tests of concrete. However, the methods have limited ranges of applicability. This study uses simulated load versus crack mouth opening displacement graphs to investigate the accuracy of the fracture strength parameter obtained from the two data reduction methods. The cohesive zone properties, in the form of tension softening diagrams used in the simulations represent tensile strengths from 2.2 to 9.3 MPa and fracture toughness values from 1.10 to 4.40 MPa rootm. Each tension softening diagram has been used in simulations of three different sizes of single edge notched specimens loaded in bending based on the two RILEM recommendations of 1990. The results of the evaluation indicate that both data reduction methods underestimate the fracture strength parameter for most of the range of tension softening diagram properties considered.