The article provides a calculation model of the complex resistance of reinforced concrete box-section structures on the combined action of bending and torsional moments, longitudinal and shear forces after the formation of spatial cracks.
The calculation model allows taking into account all the main external influences for a reinforced concrete element of a box rectangular cross section: torsional (T) and bending (M) moments, shear (Q) and longitudinal (N) forces. In this case, the action of the torsion and the shear force is reduced to the action of the flow of tangential forces along the rectangular contour of the section.

With long-term action of the load in concrete and reinforced concrete, an increase in inelastic deformations occurs, which is associated with the creep of concrete. The viscous properties of any concrete are determined by its measure of creep and creep coefficient. Modern software systems make it possible to calculate structures taking into account the rheological properties of concrete. To analyze the stress-strain state of a multi-storey building, taking into account the long-term deformation of concrete, a 45-storey model of a frame building was calculated. The creep characteristics of concrete were set according to Eurocode 2. The results of the calculation showed that the creep of concrete during its long-term deformation leads to a redistribution of forces in the building elements, an increase in floor slab deflections and an increase in the buckling of eccentrically compressed elements. A comparative analysis of the creep coefficients of high-strength concretes according to Eurocode 2 and SP 63.13330.2018 was carried out, which showed the need for an experimental study of the values specified in SP 63.13330.2018 due to a single coefficient for concretes of class B60-B100.

Experiments on the study of the effect of cyclic freezing and thawing (GCS) on the behavior of concrete show that in concrete, when exposed to negative temperatures, there is an increase in residual deformations in the form of destructive expansion of concrete. Until now, the question of the influence of the percentage of reinforcement of reinforced concrete elements on the magnitude of residual deformations of concrete expansion depending on its stress state (stretching, compression) remains little studied. In particular, how much reinforcement slows down the development of destructive processes in concrete, namely reduces the residual deformations of its expansion during sign-variable temperature effects.
The purpose of this work was an experimental study of the effect of the percentage of reinforcement on the residual deformations of concrete of reinforced concrete elements under conditions of alternating temperatures.
Concrete and reinforced concrete prisms with a size of 10x10x40 cm were adopted as prototypes, while the percentage of reinforcement varied (0.0 %; 0.5 %; 1.13 %; 2.54 %) and the level of loading of samples (0.0; 0.3; 0.7).
As a result of testing of prototypes, residual deformations of concrete expansion were obtained under conditions of cyclic freezing and thawing. Based on the results obtained, formulas are proposed for calculating the residual deformations of concrete reinforced concrete elements under alternating temperature conditions, taking into account the percentage of reinforcement.

The pliability of dense joints of panel buildings is a necessary element of mathematical models of load-bearing systems. The malleability of the same type of connections working on the shift is determined. Experimental data and normative literature were used. The existing regulatory framework and experimental studies lead to a significant variation in the pliability vertical joints working for the shear. Connections such as welding of embedded parts, reinforced dowels usually work in the elastic region, but the use of deformation diagrams makes it possible to take into account the peculiarities of the work of butt joints, cracking, nonlinear work under complex loads. The malleability of joints was determined by the shear-displacement deformation diagrams. The parameters embedded in the calculated discrete-continuum model of the building's load-bearing system under standard static loading are determined by numerical modeling using a software package. The article uses the example of a specific series of panel buildings P-44 to compare the stress-strain state at different values of compliance. The forces in the panels of the building and deflections depending on the pliability of shear joints are given.

The study provides a detailed analysis of the application of normalized deformation models in order to practically calculate such a design characteristic as crack resistance in reinforced concrete elements. For theoretical verification of the values of the moment of cracking, two calculation methods are used, based on the application of the elastic-plastic moment of cross-section resistance and a nonlinear deformation model. A comparative analysis of calculated values with experimental data is also used.
In the course of theoretical studies of the moment of cracking using these techniques, the following conclusions were made and the analysis of experimental data was made. The calculated value during the application of the elastic-plastic moment and the two-line diagram of the state of concrete does not exceed the experimental ones and has a margin of 10%.

The information model spreading throughout all lifetime of a building has to take into consideration the changes in the materials properties over time. Unlike the man-made structures with the well-defined properties, the soils are characterized by heterogeneity and variability of characteristics. The soils properties, such as a compressibility and a shear strength, are changed due to building loads, seasonal freezing-thawing processes, water content variations and other factors. The latent, slowly developing geological processes can take place at the ground. Moreover, some soils properties used for prediction, for example, a long-term settlement caused by a secondary consolidation, dissolution or decomposition of soil particles, vibration are not always determined by ordinary surveys. These properties should be verified in situ observation.
The geotechnical information models, the use of which is expected for a long time, should be created not for separate building sites, but for the territories of large enterprises, cities, or urban areas with the same type of geological conditions. This work should be preceded by the development of the technical standards, software and documents defining the responsibilities and rights of survey and design companies, investors, and municipal administrations, including the ownership of soil survey data.
As an example, the geotechnical challenges of the Arkhangelsk city territory are discussed. The main factors that should be accepted in model are following: the presence of multi-meter peat and soft clayey soils deposits, the settlement of which has not stabilized for decades, as well as fluctuations of the groundwater level caused by the setting up of drainages and clogging of their filters.

Discusses a model of a three-layer annular plate of medium thickness. It is assumed that the load on the plate is assumed to be uniformly distributed. The universal relations constructed in the normalized tensor stress space associated with the main axes of the anisotropy of the material are taken as the determining relations. The load was taken in such a way that the deflections of the middle surface of the plate were considered small in comparison with its thickness. The fixing of the plate is rigid along the external and internal contours.
Since some orthotropic materials with different resistance exhibit a nonlinear dependence of deformations on stresses, the material characteristics are taken as functions of stress intensity. As a result of the formulation of the boundary value problem, a mathematical model was developed for the analyzed class of problems, implemented as a numerical algorithm integrated into the Mathcad software package.
To solve the system of resolving differential equations of bending of annular orthotropic plates, the method of variable elasticity parameters with a finite-difference approximation of the second order of accuracy was used.

The crossbar of the transverse frame of a one–story industrial building is a truss structure that overlaps the span, in a typical solution it rests on columns pivotally. In the middle of the span there are large bending moments proportional to the square of the span, increasing the height of the crossbar and the building as a whole. The paper proposes a rigid connection of the truss structure with the crane part of the column, causing a redistribution of efforts. In the example, this made it possible to reduce the cross-section height of the crossbar from 1.4 m to 0.8 m and the weight from 28.8 t to 20.16 t. At the same time, in the middle of the span, the bending moments decreased from 2.35 MNm to 0.76, and the maximum moments equal to 1.29 MNm act on small sections near the supports. The cross section of the crane parts of the columns increased slightly, but in general the solution turned out to be more economical and the height of the coating and the building as a whole decreased by 0.6 m. The deflection in the middle of the span from the load of 0.0209 MN/m was 0.0994 m with a maximum permissible value of 0.109 m.

The results of studies of monolithic reinforced concrete frames of multi-storey buildings and reinforced concrete frames simulating fragments of such frames in over-extreme limit states caused by special actions are presented. Two options for reinforcing the beams of the frames are considered: with double reinforcement, which ensures the operation of the beam when the force flows in the frame and, accordingly, the sign of the moment change; option with double reinforcement and installation of additional indirect reinforcement in the support zones of the beams for the entire height of the section. Primary and secondary design models were built using volumetric finite elements for concrete and reinforcement rods. The obtained design parameters of deformations, crack patterns and frame failure patterns for all options are compared with each other and with the results of testing physical models of these structures. To assess the effect of mixed reinforcement on the limiting deformations of compressed concrete in over-extreme limit states, based on the theory of plasticity of concrete and reinforced concrete G.A. Geniyeva, deformation dependencies are constructed for a typical reinforced concrete element reinforced with rods in one direction and meshes in the other two under uniaxial compression and volumetric deformation.
It has been established that the use of indirect reinforcement in combination with double longitudinal reinforcement in bending elements under static-dynamic loading conditions significantly increases the ultimate deformation of the compressed zone. This reinforcement option can working way to protect monolithic reinforced concrete frames of multi-storey buildings from progressive collapse under special actions.

This study presents previously unknown and detailed materials of the creative biography of the forgotten name of the architect - Oleg Vladimirovich Marigodov (1915-1949), restored from archival and bibliographic sources. The article reveals many unknown pages of the history of restoration in the post-war years of the cities of Kursk and Belgorod on the example of the study of the creativity of O.V. Marigodov. A detailed description is given of his projects on the planning and development of certain districts and quarters of Kursk and the center of Belgorod, carried out in the post-war years during his work as an architect-technician in the architectural design workshop under the Office of the chief architect of Kursk and the Kurskoblproject: the draft layout of the Pervomaisky garden, the military cemetery, the working settlement of the rubber plant, areas of individual estate development, projects of administrative and residential buildings, etc...
The research was carried out at the expense of the State Program of the Russian Federation "Development of Science and Technology" within the framework of the Plan of Fundamental scientific research of the Ministry of Construction of Russia and RAASN.

At present, composite materials are gaining more and more development in construction, including the use of dispersed reinforced concrete, which is due to its significantly improved physical, mechanical and operational characteristics compared to traditional concrete and reinforced concrete.
The article presents the results of the influence of coarse filler in the composition of the composite on the energy and power characteristics of the crack resistance of fiber-reinforced concrete reinforced with steel anchor fibers. The process of deformation and the mechanism of destruction of steel fiber reinforced concrete have been studied.
To do this, in accordance with the provisions of GOST 29167 "Methods for determining the characteristics of crack resistance (fracture toughness) under static loading", steel-fiber-reinforced concrete sample beams were tested with control of the applied load and the deflection caused by it. Based on the data obtained, diagrams of the dependence of the load on the deflection were constructed, after their processing and additional constructions, the energy costs for static destruction, tensile strength in bending, and the stress intensity factor were determined.
It has been established that the value of the conditional specific effective energy consumption for static failure and tensile strength in bending of fiber-reinforced concrete samples with a matrix of heavy concrete with coarse aggregate turned out to be lower than that of fiber-reinforced concrete samples with a matrix of fine-grained concrete, which is explained by the lower adhesion of the steel anchor fiber to the matrix, and a corresponding decrease in their efficiency.

The article presents the results of the study of the structure, physical-mechanical and thermophysical properties of glass-ceramic materials. The charge mixture for the production of samples was obtained from siliceous rocks, kaolin, bentonite, Na₂CO₃ and KCl. Joint mechanochemical activation of the components was carried out in a planetary ball mill. The charge mixture obtained was fired in a muffle furnace at a temperature of 850 °C. The experimental results were obtained using the method of X-ray phase (XRF) analysis. The physical-mechanical and thermophysical properties of the samples are determined. The developed materials (in the form of blocks) have an apparent density of 308 to 409 kg/m³ , flexural strength up to 3.2 MPa and compressive strength up to 13 MPa, thermal conductivity from 0.081 to 0.107 W/m•°С, limiting operating temperature up to 890 °С inclusive. The materials obtained are superior in many respects to foam glass and glass ceramics from industrial waste. They can be used as thermal insulation in the construction of industrial and civil facilities