A New Method of Strengthening the Compressed Reinforced Concrete Columns Based on the Use of Concrete and Composite Materials

Abstract

Introduction. For many years strengthening of the compressed reinforced concrete structures was fulfilled by methods based on using reinforced concrete cages and outer metal frames. These are rather time-consuming and expensive processes. The implementation of composite materials in the construction industry made it possible to quicken and simplify the works on strengthening, however with regard to compressed elements it turned to be very resourcedemanding to increase the bearing capacity of rectangular or square section structures. This is primarily due to the limitation in compression strain of the longitudinally located carbon fiber materials and a large decreasing coefficient for transverse composite strengthening. However, the development of new methods of strengthening, including the one considered in this work, will increase the efficiency of composite materials located in the transverse direction by 5–10 times, depending on different variable factors. This article aims to develop and justify a new method of strengthening the reinforced concrete columns by using mixed concrete-composite reinforcement.Materials and methods. This research relies on the results of theoretical calculations. The standard variant of strengthening a compressed reinforced concrete element has been considered and calculated as well as composite materials volume has been specified. Based on the standard calculation results the proposals, which take into account the effect of a new strengthening method, have been made in this article, the detailed methodology of calculation thereof has also been presented. The results of theoretical strength calculations along with comparison of the required volume of reinforcement materials are the key issues in the analysis and drawing conclusions.Results. The research has resulted in development, calculation and justification of the new method of strengthening, which allows reducing the volume of composite materials required for strengthening the compressed reinforced concrete columns.Discussion and conclusion. Three variants of calculating the strengthening of a reinforced concrete column with composite materials have been presented and reviewed in this work. One of which is a standard one, the other two are proposed by the authors. The developed method of strengthening implies rounding of concrete followed by jacketing with composite materials. These roundings can be considered in calculation or can be referred to as structural elements. In any case, the strengthening effect received from the proposed method becomes 5.3 and 10.5 times higher. Besides, further research ideas for continuing the development and study of the method of strengthening the centrally compressed reinforced concrete columns with composite materials are given in conclusion.