Експериментально-теоретичні дослідження міцності стиснутих залізобетонних елементів з непрямим армуванням зварними сітками

Transverse reinforcement with welded meshes is used in areas of significant compressive forces, usually in local places, where it is necessary to increase the strength of concrete in axial compression. In a calculated way, such an increase in the strength of concrete is usually taken into account by introducing coefficients that were obtained on the basis of experimental researches. Calculation of the strength of such elements on the basis of empirical dependencies is a significant drawback that can lead either to overspending on materials or to insufficient reliability of structures. Improving the calculation method with transverse reinforcement is a rather promising direction. The presented work presents a method for determining the ultimate compressive stresses of concrete in compression in places of transverse reinforcement with welded meshes, based on the theory of plasticity of reinforced concrete, within which the mesh reinforcement is considered as an internal bond that limits the transverse deformations of concrete in compression and causes the emergence of reactive compressive stresses in concrete acting in the plane of the meshes. As a result, concrete within the location of the reinforcing meshes passes from a stressed state of axial to triaxial compression, which causes an increase in its strength, and at the same time the strength of the entire element in the area of the compressive force. Based on the above-mentioned premises, theoretical calculations were obtained to determine the ultimate stresses in concrete in places of reinforcement with welded meshes, which take into account the intensity of transverse reinforcement (diameter, mesh reinforcement pitch and their location along the height of the element), the strength characteristics of concrete and the corresponding reinforcement. To verify the developed calculation tool, we conducted local experimental researches of the strength of reinforced concrete elements with transverse reinforcement with welded meshes. The analysis of the results of the experimental and theoretical studies made it possible to establish the general regularities of the stress-strain state and the strength of centrally compressed elements with transverse reinforcement. As a result of comparing experimental and theoretical data, it was established that the developed calculation method for determining the strength of compressed reinforced concrete elements in zones of transverse reinforcement with welded meshes has a sufficiently high accuracy, since the ratio between the calculated and experimental load at failure was 0.87…1.06, and after further experimental testing it can be used for calculating structures