Recently，the fracture mechanics has been applied with remarkable success to the analysis of fracture phenomena of concrete such as occurrence and propagation of cracks. In the conventional FEM analysis on the basis of the tensile capacity of concrete, if the maximum principal tensile stress exceeds the tensile capacity of concrete, cracks are assumed to develop and the normal stress across a crack may be zero.
On the other hand, in the analysis of concrete by means of the fracture mechanics, the transport systems of stresses between cracked planes are considered after occurrence of cracks.
As for models of the fracture mechanics for concrete, the crack band model and the fictitious crack model are used. Furthermore, the fracture energy and the tension softening curve have an important meaning in analyzing. The analysis by using the crack band model is achieving steady results. In this approach, the analytical treatment in establishment of width of fracture process zone and modification of stress-strain matrix of cracked elements becomes complicated.
However, in the fictitious crack model, the analysis is possible only by expressing crack by separation of nodal points and propagating it one by one.
In this paper, the fictitious crack model is especially taken up and the applicablilty to concrete and the numerical procedure of this model are expialned by way of analytical examples which contain comparison with the crack band model.