This book presents formulation and numerical results of the double - K fracture parameters of concrete obtained using various analytical models. Due to several advantages of split-tension cube test, development of double-K fracture model for the split-tension cube specimen is also presented in the book. Further, application of peak load method for determining the fracture parameters of double - K fracture model is introduced in which the need of clip gauge for measurement of crack opening displacement during the test is avoided. For purpose of all the computations, cohesive crack model is developed for different test geometries.