In this thesis, the fracture process in structures with quasi-brittle materials was investigated using the finite element method based on the cohesive zone model. Two different cohesive model formulations are presented: a potential formulation, the PPR model, and a formulation for the bi-linear and linearexponential models. These formulations were applied in the simulation of fracture propagation in concrete specimens reinforced with steel-fibers. The specimens were subjected to Mode I, II and mixed-mode loading through the direct tensile, shear and bending tests. The analyses were simulated in the Abaqus . The good applicability of the cohesive zone model for fracture propagation analysis in quasi-brittle materials were demonstrated with the performed simulations. The PPR potential model and the linear-exponential model presented better results in tests with concrete reinforced with steel-fiber specimens.