We continue to study the stress-strain state of reinforced concrete bonded and unbonded prestressed beams. In this article, we consider the process of crack formation in such structures, relying on the results of testing experimental reinforced concrete samples of bonded and unbonded prestressed beams, as well as their three-dimensional models created in the Abaqus software complex. The results of calculating prototypes according to current standards are compared with experimental data and calculation of a finite element beam model in the Abaqus complex software complex, on the basis of which recommendations are proposed for calculating the crack resistance of prestressed reinforced concrete bonded and unbonded structures. In the course of the analysis, the following conclusions were made: 1) The real crack resistance exceeds the theoretical and obtained during testing of finite element models. When the effect of reinforcement is taken into account, the discrepancy is considerably reduced, so it should be included in the calculation for a more accurate determination of crack resistance. 2. Unbonded prestressed structures have lower crack resistance compared to classical bonded reinforcement.

Keywords: reinforced concrete beams,prestressed structures, bond, rainforcement, crack resistance