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Introduction. Reinforced concrete structures affected by various aggressive environments operate under off-center compression. Fiber-reinforced polymer (FRP) rebars replacing steel reinforcement in these structures are capable of increasing their durability and decreasing operating costs. However, the use of FRP rebars is limited by insufficient previous research into the methods of designing such constructions. The majority of international regulatory technical documents concerning the design of concrete structures reinforced with FRP rebars indicate the necessity of detailed studies into the stress-strain state of these structures under compression.Aim. To study the effect of longitude and shear reinforcement on load-bearing characteristic of stressed concrete samples reinforced with longitudinal glass fiber-reinforced polymer (GFRP) rebars.Materials and methods. The study was carried out using a concrete prism sample with different parameters of longitudinal and shear reinforcement. Five types of GFRP rebars differing in mechanical properties, as well as anchorage were considered. Shear reinforcement of the samples was performed with metal clamps at different pitches. The sample testing was fulfilled using centric compression with static load.Results. The strength values of compressed concrete samples reinforced with GFRP rebars were obtained. An increase of up to 19 % in the strength of compressed concrete samples reinforced with GFRP rebars was found in comparison with non-reinforced samples.Conclusions. The strength of compressed concrete elements increases when reinforced with glass fiber-reinforced polymer rebars. The degree of increase in the strength of such elements depends on the number of longitudinal reinforcements, as well as shear reinforcement pitch. The effect of the type of anchorage of GFRP rebars along with the values of its compression resistance on the strength of compressed concrete elements have not been established.

Introduction. The current standards for the design of concrete and reinforced concrete structures provide no methods for calculating the strength of the oblique sections in bending elements of various cross-sectional shape under the action of transverse forces. This prompts the designers to use simplifications in calculation of such elements, which, in some cases, may lead to excessive consumption of transverse reinforcement or the strength underestimation.Aim. The performed study was aimed at assessing the reliability of a new method for calculating the strength of oblique sections in bending reinforced concrete structures with a non-rectangular cross-sectional shape.Materials and methods. The reliability assessment of a new procedure for calculating oblique sections of a various cross-sectional shape was performed by the comparison between the calculated and experimental values of the transverse force received by the oblique section of reinforced concrete elements with various cross-sectional shape. The study considers the oblique bending tests of the samples with an annular, circular, and square cross-sectional shape, as well as T-shaped samples with a crossbar both in a stretched and compressed zone. The reliability assessment was performed using generally accepted methods of statistical analysis.Results. The distributions of ratios of the experimental and calculated values of the destructive transverse force for various-section test samples were obtained to be close to normal ones. According to the results of the reliability assessment, the proposed procedure of calculating the strength of oblique sections in elements with various cross-sectional shape was established to be comparable with the procedure accepted in the SP 63.13330.2018 Rules and Regulations for calculating rectangular cross-section elements in terms of the accuracy and reliability indices.Conclusions. The proposed procedure of calculating the strength of oblique sections in elements with various cross-sectional shape was determined to be comparable with the procedure accepted in the SP 63.13330.2018 Rules and Regulations for calculating rectangular cross-section elements in terms of the accuracy and reliability indices.