State-of-the-Art Analyses for the Fracture Energy of Concrete: Revisited

Abstract

Fracture mechanics of concrete play an important role in describing fracture process in concrete members. Fracture energy is a key parameter in employing the fracture mechanics in concrete structures. To determine the fracture energy of concrete, the formation and progress of fracture process zone in front of crack tip have to be identified appropriately. Therefore, the development of fracture process zone was modeled in this study based on the concept of fractured volume. The fractured volume was defined in terms of the length and width of the fracture process zone. The length of fracture process zone was modeled based on the data of cohesive stress analyses. The continuous change of length and width of fracture process zone was modeled as a crack propagates along the ligament. The present model may allow more realistic evaluation and interpretation for the fracture energy of concrete in that it gives the fracture energy per unit volume of concrete in addition to the fracture energy per unit area of concrete. However, further study is necessary to clarify the patterns of change of FPZ size along the ligament according to various member sizes because the decreasing pattern of FPZ size according to crack-to-depth ratio may be different for different sizes of members. This task must be also implemented for the variation of width of FPZ for different member sizes. This will enable us to describe reasonably the fracture energy of concrete per unit volume for any sizes of members.