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The article is devoted to the problem of choosing the optimal parameters of reinforced concrete rectangular beams with single reinforcement. The analysis of the dependence of the cost of a single-span hinged-supported reinforced concrete beam on the selected parameters of its cross section under the action of a uniformly distributed load. The optimal range of cross-sectional parameters of reinforced concrete articulated beams (height, width, class of concrete and reinforcement, area and reinforcement pitch) was determined depending on the value of the uniformly distributed external load. Strength calculation of reinforced concrete beams is based on the traditional method given in the SR.63.13330.2018 “Concrete and reinforced concrete structures.” The cost of reinforced concrete beams was calculated under the influence of various uniformly distributed loads. The first option, where the width of the beams was constant and the section heights varied between 250 and 1000 mm. The second option, when the heights of the beams were taken equal, and the widths of the beams were in the range from 100 to 500 mm. The recommended height and width of the beam section for the specified value span in the investigated range of loads was set.

The features of the resistance of the support nodes of flexible reinforced concrete crossbars are considered taking into account the temperature effects. As the main area of work, a theoretical study of the influence of temperature effects on the strength and configuration of embedded metal parts and welds of the support nodes of prefabricated crossbars of various types is presented, which is an expression of the result achieved. The documents of the regulatory framework governing the design and construction activities in the Russian Federation, the existing constructive solutions of the support nodes, as well as the works of domestic and foreign scientists corresponding to the studies in this area are used. Research methods are structural and analytical analysis. Regulatory and scientific-methodological materials were studied, which made it possible to establish the parameters and factors affecting the constructive solution of the support nodes of flexible concrete elements. On this basis, proposals for improving the calculation and design solutions of support nodes are substantiated. Proposals have been developed for the calculation and design of support nodes taking into account temperature effects. It was revealed that the influence of temperature deformations significantly affects the operation of the support unit. The boundary ranges of temperatures and element sizes are determined at which the consideration of temperature effects is necessary. The features of the stress-strain state of the support node are clarified. Design recommendations are provided that provide strength and durability of the structure.

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The paper considers the peculiarities of the stress-strain state in the zone of junction of the slab of slabs with the joint using conventional and high-strength reinforcement. The maximum stresses in the stretched concrete before cracking correspond to the tensile strength of the concrete, and the stresses in the reinforcement before cracking depend on the reduction factor and were calculated for various classes of concrete. After the formation of cracks, the increase in stresses in the tensioned reinforcement depends on the width of the crack opening and the deformation of the reinforcement between the cracks. The paper shows that with a sufficient width of crack opening and a certain distance between the cracks, high-strength reinforcement can be used to increase the bearing capacity of the support sections of the plate. The total stresses in the reinforcement were calculated for different crack opening widths and different distances between the cracks, the results of which were used to plot the graphs. The graphs of the dependence of the content of high-strength reinforcement on the strength of the normal section, as well as the graphs of the growth of strength with different ratios of the number of rods, are plotted. According to the results of the work, it can be seen that, depending on the class of high-strength reinforcement and its quantity, the strength of normal sections can be increased up to two times.