The article analyzes the hypothesis of deplanation of angular deformations in reinforced concrete structures during bending with torsion. A simple method from the field of the grid methods for approximating the deformations of complex functions under the 3D stress state is considered. Diagrams of angular and linear deformations in such structures were built and analyzed to find these deformations, bending and torques perceived by the concrete of the compressed area using the accepted hypotheses and coefficients for projecting normal and shear stresses (strains) through diagrams of compressed concrete and working reinforcement. Approximating the calculated section by small squares, a spatial surface of deformations was constructed. This is with the corresponding gradients of these deformations in the section with a crack, and on this basis, expressions were written for the total longitudinal deformations in the section and shear deformations in the section of the element during bending with torsion. Using the membrane analogy of the Timoshenko-Goodyear stress functions and the proposed version of new complex functions from the field of the grid method, an analysis was made of its error, when we find the value of complex functions at the considered characteristic points (2%) and at any points of the cross section (7%).
The use of the proposed hypotheses and the given version of complex functions makes it possible considering the warping of the 3D stressed section of a reinforced concrete element with cracks undergoing bending with torsion.

A quality index of the coefficient grid inverse Cauchy problem for beams in building structures is proposed. The indicator is based on the theory of regularization of inverse problems. An articulated support of a beam on a column is modeled analytically and by a full-scale experiment. Models of measurement and calculation are investigated for a uniform continuous error rate of deflection measurement and calculation of beam identification parameters. Models differ in various combinations of types of external load.

A measure of the influence of the error of the measuring instrument and the distribution of approximation grid nodes on the error in determining the coefficients of the beam deflection equation with a fixed first coefficient is proposed. The measure of influence is described by the dimensionless absolute condition number of the problem. The values of the dimensionless absolute condition number and the quality index of the problem are analyzed depending on the distribution of approximation grid nodes, the error of the measuring instrument, and the type of measurement and calculation model.

It is proposed to use the obtained analytical dependencies for the analysis of building structures at the stage of experimental and theoretical studies.

Thin-web steel girders attract with their efficiency in bending work. For such girders, the issue of ensuring local stability becomes very relevant. Calculation formulas in most cases are complex and have a limited scope of application. While the calculations based on FE models make it possible to more universally consider all the specifics of the designed element. The article deals with the calculation of the stability of the web girder under the combination of patch and shear loading by finite element modelling. Numerical models have been created and a comparative analysis with experimental results has been carried out. A description of the principles for constructing FE models (mesh size, material model, etc.), which must be observed when assessing the resistance and behaviour of beams with thin web, is presented. Sensitivity analysis of the FE model to the input parameters revealed the most important parameters (yield strength of steel, web thickness), the uncertainty of which must be taken into account when creating FE models. The convergence of the results allows the use of the finite element method in the design of steel beams for a qualitative and quantitative assessment of the resistance. However, further development of unified principles for creating FE models and their verification on a larger amount of experimental data is required, as well as the determination of partial factors to take into account the variability and uncertainty of the results obtained, taking into account the regulated reliability parameters.

The stone vaults of historical buildings are considered, which, due to a decrease in bearing capacity, require repair and restoration work. An analysis is given of the mechanisms of destruction of cylindrical vaults depending on the ratio of their height to the span. The advantages of strengthening the vaults with the help of reinforcement with composite materials are analyzed. A description is given of the technology of surface reinforcement of stone structures using composite materials on a polymer cement matrix FRCM (Fiber Reinforced Cementitious Matrix). The technique of experimental studies of models of reinforced and non-reinforced vaults is given. On the basis of the experiment, it is shown that the effectiveness of the reinforcement of the vaults is determined by the features of their stress-strain state and failure mechanisms. In particular, the effectiveness of reinforcement increases with an increase in the ratio of the height of the vaults to its span. These results are substantiated by the fact that in high arches the ratio of bending moments and longitudinal forces is dominant, and in the case of flat arches, longitudinal and transverse forces dominate in their sections, and destruction occurs in the form of shearing along inclined sections. Also, the effectiveness of reinforcement increases with their asymmetric loading relative to the middle of the span. According to the results of the study, graphs of the dependence of the maximum vertical displacements of the vaults were constructed, showing a significant effect of reinforcement on increasing their rigidity. In addition, it is emphasized that by now there is a need for a stable theory of the strength of complex stone structures - curvilinear, vaulted and others that are in a complex stress state. Its appearance can significantly simplify and unify the calculations made when examining stone buildings, drawing up projects for their restoration and reconstruction, and solve the problems of the strength of the masonry of modern facade systems.

There are practically no results of experimental studies of elements made of compressed reinforced concrete damaged by corrosion in the scientific literature. As a result, it is almost impossible to reliably assess the state of deformation-deformation of these structures, especially under dynamic loads. For experimental studies, 37 samples of reinforced concrete were made-columns of square cross-section with dimensions of 100x100 mm, height of 700 mm. Local corrosion damages of concrete and reinforcement were created in reinforced concrete samples, while a concentrated (37%) hydrochloric acid (HCL) solution was used as an aggressor to accelerate the corrosion of elements. The article describes experimental studies on changing the dynamic properties of reinforced concrete elements that undergo corrosion during eccentrically compression. Based on strain gauge data, it was found that corrosion damage leads to a decrease in the height of the compressed concrete section by reducing the cross-section of the stretched reinforcing bars, as well as to the lack of joint work of reinforcing bars with concrete. According to strain measurement data, deformations of uncompressed and undamaged sections were obtained, which showed that the deformation diagrams fundamentally differ in their contour. The results obtained as a result of the study of the nature of deformation of reinforcement and concrete allowed us to assess the state of deformation stress of damaged and non- corroded structures according to the parameter Ne-1/r (curvature). The effect of corrosion damage on the nature of destruction of eccentrically compressed elements has been established.

The aim of this work is to obtain information about the condition of the sludge tank supporting and enclosing building structures, identifying and fixing existing defects in order to assess their possible impact on structures during its further operation. Archival surveys were carried out, site documentation was selected and studied, load-bearing structures engineering measurements were carried out, building structures were inspected, and the structural condition was photographed selectively, graphic materials were made, technical conclusions were drawn up with conclusions and recommendations for further structures safe operation in order to achieve this goal. The technical surveying included a building structures external examination with damages fixation. The structures general technical condition of the, the presence and nature of the defect’s propagation were previously visually recorded, and then refined using measuring equipment. Verification calculations were also carried out with the design and current load analysis on the sludge tank elements, and the tank supporting structures concrete strength was determined by the ultrasonic method.

There is now a growing interest in the design and construction of shells whose median surfaces cannot be defined by analytic formulas, i.e. it is difficult to apply geometric modeling, and shell structures of the folded type formed by the intersection of flat or curvilinear elements. These structures are executed in the style of digital architecture or experimental methods. Based on the research of descriptive and analytical geometry, architects in the 20th and early 21st century created many memorable folded structures of various purposes. This is illustrated in the article on the example of many flat-sided structures. The illustrations found on the Internet and the author's personal photos were used. Based on the carried-out research it is concluded that flat-sided folds were used very widely in various fields of architecture and construction. The availability of numerical methods of calculation makes it possible to design structures of various degrees of complexity. This is confirmed by references to numerous sources used. However, some architects disagree with this conclusion, believing that despite many attempts on folding, it remains one of the least studied forms in architecture.

For the first time, comprehensive surveys of urban and suburban estates of the Kursk Territory are carried out. 18th century (measurements, photo fixation, natural sketches), archival and printed sources are identified that resurrect images of lost noble and merchant estates, and a general analysis of the topic under study is carried out. An important result of the study is the disclosure of the peculiarities of the influence of the architecture of Moscow and the Zamoskovskiy Territory on other regions of the country (on the example of the Kursk Territory), which opens up new pages of the multifaceted culture, architecture and construction of the Russian province. Introduction into scientific circulation of specific architectural monuments of the Zamoskovskiy and Kursk regions of a given period, their in-depth study can be used in scientific literature, lecture courses and design and security documentation.

The article presents the results of the effect of a complex additive on improving the physical and mechanical characteristics of the material. The evaluation of the physical and mechanical characteristics of concrete was made for four types of concrete. The main parameters were: setting time, compressive and flexural strength, water absorption. In the presented work the authors used a complex additive containing in its composition alkali (caustic soda), post-alcoholic bard (alcohol production waste) and hardening regulator (gypsum) in different ratios. It is shown that the combined use in the composition of a complex additive, which has well-compatible mechanisms of their influence on the processes of hydration, setting and hardening of the cement mass, mutually complements and enhances the effect of each ingredient of the additive. Increasing the concentration of the complex additive in the cement mixture up to 7% of the cement mass not only affects the process of cement mortar liquefaction, shortening the time of setting and hardening of the cement mass, but also increases the compressive strength of the cement in all periods of hardening. The analysis suggests that the complex additive provides a reduction in water absorption of concrete. It has been revealed that concrete with the studied complex additive has high physical and mechanical properties. The optimum dosages of the considered additive have been found and used in the present work.

The main task of obtaining concrete, in particular for irrigation and drainage construction, with increased performance by modifying their structure and properties with complex additives is becoming more and more relevant every year. Within the framework of these studies, issues related to the modification of the composition of heavy concrete with the use of a complex chemical additive consisting of the superplasticizer Melflux 5581 F and the water-soluble polymer additive Polydon-A were considered.
The aim of the study is to develop a scientifically based technological solution that provides the production of heavy concrete based on a polydisperse binder with a complex polymer modifier (Melflux + Polydon-A) for agricultural construction.
The object of study is heavy concrete based on a polydisperse binder with a complex polymeric modifier for agricultural construction.
Research results: The resulting modified concrete is characterized by an increase in compressive and tensile strength in bending, a conditional stress intensity factor, water absorption, water resistance and frost resistance, which makes it possible to recommend it for the production of building products and structures operating in harsh operating conditions, in particular, for trays irrigation systems.