The object of research is the residual resource of the structures of buildings and structures after various influences. The residual resource is the total operating time of the object from the moment of monitoring its technical condition to the transition to the limit state.The calculation methods recommended by the current regulatory documents of Ukraine do not allow predicting the probability of failures, an increase in the number of structural defects and deformations over time and really assessing the possibility of further operation in such conditions. One of the most problematic places is determination of the technical condition of structures of buildings and structures operating under various influences (in an aggressive environment, with forced displacements of supports, possible high-temperature influences, etc.).It is shown that the residual life of the structures of buildings and structures that suffered damage during operation after various influences can be reassigned due to reinforcement. In this case, the main question remains the determination of the physical and mechanical characteristics of the materials that were used in the manufacture of structures, as well as the calculation of structures for the justified purpose of the cross sections of reinforcing elements. Characteristics of materials are determined during the observation. During the observation, various methods were used to determine the physical and mechanical characteristics of structural materials (concrete, reinforcement, steel, brickwork, etc.), which are usually non-destructive. Non-destructive methods can be applied in cases where this is possible under the conditions of operation of structures, for example, the removal of fragments of metal, reinforcement or concrete from lightly loaded elements.The possibility of reassigning the residual resource is determined by comparing the values of the bearing capacity of the structures with acting values. The bearing capacity of the structures is determined using the values of the characteristics of materials and parameters (cross-sectional dimensions, geometric dimensions taking into account corrosion wear, etc.), which were obtained during the observation. The magnitudes of the forces acting in the structures of buildings and structures are determined by modeling their work using the finite element method and modern computing systems. Thanks to this procedure, it is possible to obtain the efforts that could arise in the structures of the building and reinforcement. Thanks to this, it is possible to make a decision on the reassignment of the remaining life of the structures, that is, the possibility of further operation, the need for reinforcement or replacement.