Shevchenko O. Estimation of the stress-strain state of steel reinforced concrete columns strengthened with an adhesive joint

The dissertation is devoted to theoretical and experimental research of steel reinforced concrete columns reinforced with adhesive joints. The performed analysis of literature sources allows us to draw a conclusion about the relevance of the calculation and determination of the stress-strain state of such structures and their use in the construction and reconstruction of buildings. Both domestic and foreign scientists have studied various aspects of this problem. Therefore, the creation, research of bearing capacity and stress-strain state of steel reinforced concrete structures with external reinforcement which reinforced with adhesive joints and the development of methods for their calculation is relevant. A review of scientific literature on steel reinforced concrete structures used in the construction and reconstruction of buildings and structures has been carried out. The properties and possibilities of application of glues for strengthening of building constructions were investigated. The analysis of the main provisions of fire design and the possibility of their application for steel reinforced concrete structures. The mechanical and deformation strain properties of materials, as well as the method of calculation of fire resistance of such structures according to current state standards depending on the selected steel grade and concrete class were highlighted. Features of joint work of steel and concrete in steel reinforced concrete structures are considered. The analysis of the existing methods of calculation of the steel reinforced concrete columns which are strengthened during operation was provided. The algorithm for calculating steel reinforced concrete columns using the software package LIRA-SAPR was implemented. A finite element modeling of the steel reinforced concrete column was performed taking into account its strengthening with the help of glue in order to check and refine the results taking into account the physical nonlinearity, creep of concrete and redistribution of forces on the steel-glue-concrete contact. The change of the stress-strain state of steel reinforced concrete elements strengthened with an adhesive joint depending on the height and eccentricity of the load application was experimentally investigated and the nature of the loss of their bearing capacity was revealed. An analytical review of the known methods for estimating the stress-strain state and calculations of the bearing capacity of steel reinforced concrete columns strengthened with an adhesive joint. A method for estimating the stress-strain state and bearing capacity of steel reinforced concrete elements strengthened with an adhesive joint in the conditions of longitudinal compression has been developed. For the first time, experimental results on the stress-strain state of new structural solutions of steel reinforced concrete columns strengthened by gluing were obtained and the nature of their destruction was established. The constructive decisions of the steel reinforced concrete columns strengthened by means of gluing have been improved. Simplified methods for calculating steel reinforced concrete columns strengthened by gluing have been further developed.