Research Of Size Effect Law Of Fracture Toughness Of Concrete Considered Fracture Process Zone

Size effect of fracture toughness of concrete materials is a tough thing for its theory and engineering applying. Many researchers have pay a lot of time on such field with experimental and mathematic analysis, and the typical theories are :Weibull statistical theory of brittle rupture and Bazant intensity theory .This paper try to find out the solution and fundament thing of concrete size effect problem, via the effect of fracture process zone in fracture toughness calculation. The fracture between concrete material and metal ones are different ,with the microscopic fracture exist in the front of cracks, the concrete fracture mechanics must consider the fracture process zone.As long before ,the maximum loads are used with the initial crack a₀,if think about the effect of process zone, the critical crack a_c must be considered.At first, this paper has modified the fracture toughness formulation from the angle of process zone, and use a_c instead of a₀,later the shape function also be considered.Second, Weibull statistical theory of brittle rupture and Bazant intensity theory belongs to power scaling from mathematic deducation, two ones are the affection of power scaling in different situation. and the size effect of fracture toughness and intensity are connected with each other.At last ,finite element is used to test the correct of the solution, use a=a₀ and a=a_c two different situation to find out which is closer to the experimental data. and the later is better.With experimental inducation, theoretical analysis and finite element validation,the fracture toughness calculation with the process zone is valuable for size effect problem. With its effort, the fracture toughness research have double meanings in theoretical research and engineering applying.