Studying the Efficiency of Composite Longitudinal and Transverse Reinforcement for Increasing the Strength and Rigidity of Flexible Eccentrically Compressed Reinforced Concrete Poles

Abstract

Introduction. In recent years, the use of composite materials for improving the operational properties of the building constructions within the restoration process is gradually replacing the methods, developed for this purpose in the middle of the XXth century and implying the use of reinforced concrete and metal. However, the regulatory framework stipulating the process of strengthening the loadbearing structures of buildings and structures was developed based on the insufficient amount of experimental data. Due to this fact, the large number of structures, exceeding the normative limits, cannot be strengthened with the composite materials, or such strengthening incurs significant economic costs. Thus, nowadays, the experimental studies on strengthening the reinforced concrete structures with composite materials are considered to be forward-looking and relevant. The aim of this study is to analyse the results of a number of experiments conducted to investigate the use and efficiency of composite materials in construction.  Materials and Methods. To determine the level of stress in composite carbon materials of the external reinforcement of the eccentrically compressed reinforced concrete poles, the tests were carried out with four specimens. All specimens were strengthened using different reinforcement schemes. The strain gauges with 2cm active measuring grid length were installed in the zones of the most evident work of the composite materials to measure the changes of relative deformation at each load level during testing of the specimens. From 10 to 16 strain gauges were installed at each structure, depending on the importance of the zones for determining the deformations.Results. The work presents the results of the study on determining the efficiency of composite longitudinal and transverse reinforcement for increasing the rigidity and strength of flexible eccentrically compressed reinforced concrete poles. The experimental data on the composite materials’ strength, deflections and relative deformations, obtained during testing of four reinforced concrete poles, is presented. The efficiency of composite reinforcement at ultimate strength and ultimate deflections is assessed. The relative deformations in composite materials are determined and the inclusion of the reinforcement system in the work of the strengthened reinforced concrete specimens is assessed.Discussion and Conclusion. Based on the obtained results, the analysis of the composite reinforcement efficiency has been carried out, and proposals have been developed on designing the reinforcement systems of the flexible eccentrically compressed reinforced concrete poles working with the large eccentricities of the load application.