Indirect reinforcement can significantly increase the strength and deformation characteristics of concrete. For the compressed zone of reinforced concrete beams, one of the most effective options for indirect reinforcement is transverse welded mesh. At the same time, the current regulatory documents still have a number of gaps in the methodology for calculating such structures. The article presents experimental data and calculation results for three series of reinforced concrete beams with indirect reinforcement of the compressed zone. Based on the calculation results, the shortcomings of the normative methodology are shown when performing calculations within the framework of the theory of limit states and assigning design values ​​for the strength of concrete with indirect reinforcement. Conclusions are drawn about the necessary sequence for calculating the design strength and deformation characteristics of concrete with indirect reinforcement.

Keywords: indirect reinforcement, beam, welded mesh, volumetric stress state, nonlinear deformation model, stress-strain diagram

The article discusses the areas of application of the deformation model and reviews studies related to its use for various design solutions and operating conditions. A method for calculating eccentrically compressed reinforced concrete elements that takes into account second-order effects is presented. This methodology takes into account the current provisions of regulatory documents. A selection of experimental data was made for flexible eccentrically compressed columns. Calculations of bearing capacity and deflections for selected samples were performed. Various forms of concrete deformation diagrams were used in the calculations. Based on comparison with experimental data, conclusions are drawn about the applicability of various types of diagrams for calculating bearing capacity and deflections.

Keywords: deformation model, stress-strain diagram, eccentrically compressed element, flexibility

The deformation model is a fairly flexible tool, which allows solving a wide range of problems in the design of reinforced concrete structures. At the same time, important tasks are the choice of a material stress-strain diagram that most accurately reflects the deformation of the structure under the accepted conditions, and the assessment of the influence of the type of the accepted diagram on the results of calculating the bearing capacity and deformations of the structure. The article compares the results of calculating the bearing capacity and curvature of beams depending on the shape of the accepted concrete deformation diagram and the structural parameters of the element (section height and reinforcement ratio).

Keywords: deformation model, stress-strain diagram, bending element, transverse section

When designing flat reinforced concrete slabs, the most complex and responsible structural unit is the area where the slab is supported by the column. This is due to the action of large concentrated efforts and the greatest density of reinforcement. In view of this, the issue of choosing calculation methods that most accurately estimate the punching capacity for suchstructural units is relevant. The article analyzed experimental data for 73 samples of flat reinforced concrete slabs without shear reinforcement from 10 different sources and compared with the results of calculations of the punching shear resistance according to SP 63.13330.2018, EN 1992 Eurocode 2 and Model Code 2010.

Keywords: punching shear resistance, flat reinforced concrete slab, static load

Setting the indirect reinforcement in the form of cross welded mesh is one of the effective ways to increase the strength and deformation characteristics of compressed concrete. When performing engineering calculations of structures with indirect reinforcement, in order to ensure the required reliability, it is necessary to use the design values of the strength of materials. At the same time, initially the calculation formulas were derived and analyzed for the experimental average strength values, which are significantly higher than the design ones. Based on the results of the calculations, it was found that a simple substitution of the calculated strength values in the formulas leads to an overestimation of the strength and ultimate compressibility values of concrete with indirect reinforcement.

Keywords: indirect reinforcement, welded mesh, volumetric stress state, compression diagram