COMPARISONS OF CONCRETE FRACTURE MODELS

Fracture properties for linear elastic fracture mechanics (LEFM), sing ular-fracture process zone (S-FPZ), and nonsingular-fracture process z one (NS-FPZ) models were determined from the experimental results of t hree-point bend tests. The responses for each fracture model were nume rically calculated and compared. All three fracture models could simul ate the measured load and crack mouth opening displacement (CMOD) vers us load-point displacement relations. However, for the LEFM model the stress intensity factor needed to increase continuously with crack ext ension, and for the S-FPZ model the fracture process zone characterist ics need to change continuously if the critical stress intensity facto r was to remain constant. The LEFM model showed the largest resistance and the slowest crack extension, while the NS-FPZ model showed the sm allest resistance and the fastest crack extension. The responses for t he S-FPZ model were intermediate between those for the LEFM and NS-FPZ models and the total fracture energy densities for the S-FPZ and NS-F PZ models were equal.