Comparisons of Concrete Fracture Models

Abstract

Fracture properties for linear elastic fracture mechanics (LEFM), singular-fracture process zone (S-FPZ), and nonsingular-fracture process zone (NS-FPZ) models were determined from the experimental results of three-point bend tests. The responses for each fracture model were numerically calculated and compared. All three fracture models could simulate the measured load and crack mouth opening displacement (CMOD) versus load-point displacement relations. However, for the LEFM model the stress intensity factor needed to increase continuously with crack extension, and for the S-FPZ model the fracture process zone characteristics need to change continuously if the critical stress intensity factor was to remain constant. The LEFM model showed the largest resistance and the slowest crack extension, while the NS-FPZ model showed the smallest resistance and the fastest crack extension. The responses for the 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-FPZ models were equal.