The load-bearing capacity of reinforced concrete beams operated in difficult conditions
Students Name: Finenko Arsen
Qualification Level: master (ESP)
Speciality: Building and Civil Engineering
Institute: Institute of Civil Engineering and Building Systems
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: Finenko A.S., Blikharskyi Z.Ya. (supervisor). The load-bearing capacity of reinforced concrete beams operated in difficult conditions. Master’s thesis. ? Lviv Polytechnic National University, Lviv, 2023. Extended annotation Reinforced concrete structures are widely used in buildings of all purposes: from residential and civil to various types of special-purpose structures. Considering such a wide area of application, it is worth noting that the maintenance of reinforced concrete structures is always an urgent task. This especially applies to complex cases of a stress-strain state: torsion, bi-axial bending, shear, etc. All these cases are difficult to diagnose, design and especially to strengthen. This master’s thesis is an investigation of the shear strength of reinforced concrete beams that need to be strengthened. Such a case occurs very often in design practice, but the definition of its bearing capacity has not yet been sufficiently studied. The aim of the work is since at this, economically difficult, stage of development of the construction industry, the issue related to the construction of new construction objects is less expedient than the reconstruction, modernization, and strengthening of existing structures. Among the modern methods of strengthening reinforced concrete structures, strengthened with high-strength composite materials can be singled out. Such materials include composite materials, which are made based on Kevlar, carbon, and other fibers, in the form of strips of woven fabric. The ease of installation of such reinforcement allows you to perform it extremely quickly, without significant delays. One of these methods is reinforcement with a mesh made of P.B.O. (polyparaphenylenebenzoxazole) fibers in an inorganic stabilized matrix (FRCM system RuredilXMeshGold). When using this method of strengthening, the shear and bending strength of concrete increases. Concrete strength is one of the main factors in assessing the technical condition and serviceability of reinforced concrete beam elements. In this regard, the research on the strength and deformability of reinforced concrete structures strengthened with the RuredilXMeshGold system is extremely important for the construction industry. Based on the research results, methods for calculating the reinforced concrete elements can be developed. The purpose of the work is to determine experimentally and theoretically the bearing capacity of inclined sections of reinforced concrete beams reinforced with composite material, as well as to improve the calculation method, to develop recommendations regarding the principles of high-quality and reliable application and design of reinforcements from composite material. The object of the study: reinforced concrete beams without transverse rebar in the support zone strengthened with a composite system. The subject of the study: the shear bearing capacity of reinforced concrete beams strengthened with composite materials. The set goal of the research is achieved based on the following tasks: - using experiments to investigate the stress-strain state of reinforced concrete beams on the shear strengthened with composite material; - to develop a technique for strengthening reinforced concrete beams on the shear with a composite fabric, followed by its application in practice; - based on the experimental and theoretical part, develop recommendations for the reliable application and design of reinforcement of reinforced concrete beams on the shear with composite fabric. - determining the effectiveness and expediency of using composite materials in construction based on experiments and calculations. The research methods are to analyze the currently existing technical literature and scientific publications on the principles of using composite materials as reinforcement of inclined sections of reinforced concrete beams. Use the mechanical method of determining strains, using mechanical clock-type indicators. Calculations of reinforced concrete structures should be carried out according to the current codes. The practical significance lies in the possibility of using the obtained results in the calculation of reinforced concrete beams on the shear, and in the assessment of the technical condition, bearing capacity, and operational suitability of reinforced concrete structures. Recommendations for the use of Kevlar fabric in reinforcing reinforced concrete beams have been developed. An algorithm for calculating the reinforcement of reinforced concrete beams on the shear without transverse reinforcement for the perception of transverse force and its practical use has been developed. Keywords: reinforced concrete beams, shear strength, composite materials, strengthening, stress-strain state. References: 1. DSTU B B.2.6.-156: 2010 "Concrete and reinforced concrete structures made of heavy concrete. Design rules "- Kyiv: Ministry of Regional Development of Ukraine, 2010. (State building codes). 2. DBN B.2.6-98:2009 “Concrete and reinforced concrete structures. Main provisions”: - Kyiv: Ministry of Regional Development of Ukraine, State Enterprise “Ukrarchbudinform”, 2011. - 71 p. - (State building codes). 3. DSTU N B B.2.6-185: 2012 "Guidelines for the design and manufacture of concrete structures with non-metallic composite reinforcement" Kyiv: Ministry of Regional Development of Ukraine, 2013. (State building codes). 4. Externally bonded FRP reinforcement for RC structures: Technical report fib, bulletin 14, 2001. – 130 p. 5. Ruredil spa Technical Department. Instruction for the Planning of Static Consolidation Interventions through the use of Fibre Reinforced Cementitious Matrix - FRCM. – Milan, 2008. – 201p.