Increasing the Strength and Rigidity of Reinforced Concrete Eccentrically Compressed Elements with Carbon Fiber Reinforcement

Introduction. Existing methods of reinforced concrete structures strengthening are very expensive and time-consuming. The development of new strengthening systems allowing to reduce time and cost of works is perspective and relevant task. Modern methods of strengthening with composite materials are insufficiently studied in Russia. Particularly if the behavior of composite materials in the reinforced concrete structures is concerned. The lack of research in this area leads to the overrun of materials and increase in the cost of structures’ strengthening. The aim of this work is to study the relative deformations of composite materials in the longitudinal and transverse directions during the operation of eccentrically compressed flexible reinforced concrete poles.Materials and methods. The factual basis for the research are the results of experimental studies of the strength and deformability of eccentrically compressed reinforced concrete poles, strengthened with various types of composite external reinforcement. In the most loaded zones of the composite reinforcement, the 2 cm-long strain gauges were glued, capable of detecting changes in relative deformations up to 0.001 mm. In total, the results of operation of 5 poles were used in the analysis. During the experiment, deflections and relative deformations of concrete and composite materials were determined.Results. In the result of experimental studies, relative deformations of composite materials in the longitudinal and transverse directions were obtained. The measurements were carried out at a stepwise increasing load equal to 10 % of the breaking load. Based on the data obtained, graphs of the dependence of the change in relative deformations on the load levels were plotted for each tested sample. In addition to the readings of strain gauges, deflections of tested samples were obtained during testing and graphically presented.Discussion and Conclusions. The obtained experimental data on deflections and relative deformations in composite materials made it possible to determine the zones of the most and least strained sections of the composite reinforcement. Based on the analysis of these data, conclusions were drawn about the development of new strengthening systems that can significantly save the amount of composite materials used without reducing their efficiency.