In the present contribution, the cohesive crack model was applied to the masonry arches. The model used is an elasto-plastic model able to coherently describe the behaviour of materials as it uses a couple of constitutive laws: •??A tension - strain relationship, which describes the elastic and hardening behaviour of the integral material up to the ultimate tension u; •??A tension - opening of the slot relationship, which describes the "softening" behaviour of the cracked material, up to the critical opening wc, in addition to which the interaction between the slit faces is annulated. In the '80s an algorithm of calculation was developed, it was called "Frana", allowing it to apply the model of the cohesive crack to beam segments, simply supported, subject to simple bending moment.