The assumptions of mathematical models for calculating the crack resistance of reinforced concrete structures are considered. For each of them, an analysis was carried out to determine whether they correspond to reality throughout the entire life cycle of the structure: from the hardening of the concrete mix to destruction. Based on the results of the analysis, it was proposed to use only one single calculation at the level of standards to assess the crack resistance of structures - according to the crack opening width, acrc. So, for example, at a certain value of acrc, the structure will still remain airtight (the cracks will be non-through), and if this value is exceeded, it will not. At the same time, the calculations already available in the norms for limiting permeability and the safety of reinforcement will still remain in demand. At the junction of the theory of damage accumulation and nonlinear fracture mechanics, a compressed algorithm is proposed for possibly taking into account the influence of cracks at all scale levels of the concrete structure, the key for which is the normalization of the statistical parameters of the distribution of discontinuities by diameters, lengths, openings, depths, directions, distances between discontinuities, etc.

Keywords: reinforced concrete, crack resistance, cracking moment, crack width, plasticity coefficient, damageability, non-linear fracture mechanics

The study of statically indeterminate reinforced concrete structures at the present stage is possible with the help of software systems capable of taking into account the nonlinear work of the material, which allows us to fully assess the stress-strain state for a different redistribution of emerging forces provoked by corrosion damage to reinforcement and concrete. Numerical studies of 14 models with corrosion damage in the upper section of a two-span beam in the Ansys software package have been performed. Load-deflection graphs are presented depending on the percentage of corrosion damage. The dependences of the redistribution of tensile forces in the beam reinforcement with different percentages of corrosion damage are shown. It is established that with damages up to 10%, there is a sharp increase in the tensile forces in the span reinforcement of the beams. It is determined that with corrosion damage to the beam up to 70%, the forces in the supporting reinforcement increase to 10%.

Keywords: reinforced concrete beam, redistribution of forces, plastic hinge, corrosion of reinforced concrete, numerical calculation, bearing capacity

Currently, the energy efficiency of buildings is one of the most pressing economic and environmental problems. Reducing energy costs not only minimizes building maintenance costs, but also reduces the negative impact on the environment. This article deals with the problem of increasing the energy efficiency of the enclosing structures of polyclinic buildings and proposes a method for measuring the economic efficiency of the proposed enclosing structures of municipal polyclinics in Moscow. The implementation of an energy-efficient project for the reconstruction of polyclinic buildings requires an integrated approach, which includes the selection of optimal materials and structures, a thorough analysis and calculation of energy efficiency by measuring the savings in heat loss after the reconstruction of buildings. The implementation of this approach will reduce heat loss and increase the comfort of staying inside the buildings.

Keywords: energy efficiency, heat losses, reconstruction, enclosing structures, medical and healthcare institutions

In order to form comprehensive decisions on the organization of traffic, realizing long-term strategic directions for ensuring the efficiency of traffic organization and improving activities in the field of traffic organization, it is necessary to use the means of mathematical modeling of traffic flows. The main indicators of the effectiveness of traffic management are improving road safety, reducing the number of transport delays and increasing the capacity of the road network, as well as reducing the negative impact on the environment of vehicles.

Keywords: intensity, traffic management, traffic flow, traffic light regulation, traffic accident, accident focus, transport hub, accident rate, traffic safety, traffic capacity

The value of the efficiency of domestic gas boilers of the brand Baxi ECO-4S 24 with various schemes of air supply and smoke removal is considered. The difference in the calculated efficiency values and the passport values is analyzed.

Keywords: efficiency, flue gas discharge, household gas boiler, thermal balance, energy efficiency

The article presents the results of a comparative analysis of practical calculations of driven and bored piles, which have similar geometric parameters and common geological conditions of construction sites. Taking into account the peculiarities of the use of these piles and the available experimental data, the paper analyzes the calculated values of their bearing capacity and gives an engineering assessment of the results of the calculation. The quantitative difference between the determined parameters of the bearing capacity of piles - friction along the lateral surface and frontal resistance, is clearly shown in the constructed diagrams. So, when using the standard values of the coefficients to determine the bearing capacity of piles, we have a significant excess of this parameter for driven piles. The need to use more gentle methods of driving piles to the design depth leads to the possibility of using the technology of arranging bored piles, which have a lower bearing capacity with the same parameters as driven piles. This feature should be taken into account in engineering calculations when selecting the optimal dimensions of bored piles.

Keywords: driven piles, bored piles, geological conditions, engineering calculations, bearing capacity

Determination of pile bearing capacity located in collapsible soils. This work simulates the tests in the Plaxis 2D software system, and also determines the bearing capacity in accordance with paragraph 9.9 of SP 24.13330.2021 Pile foundations. Modeling of three capacity tests lead to recieve different results according to chosen method of tne results evaluation. Based on the results of the article the imperfection of the current Russian regulatory document in the field of field testing of piles was revealed. However comparing of the test results was made with analytical calculation of pile bearing capacity.

Keywords: collapsible soils, pile bearing capacity, pile tests, finite element modeling, Plaxis

For the possibility of installing overhead cranes, steel columns of an industrial building are made in steps, with the allocation of crane and crane parts. The basis of the upper and lower parts of the column are steel I-beams with a mismatch of the central axes. As part of the work, variant modeling (using CAD) of a steel column that is part of the U-shaped frames of industrial buildings, consisting of crane and crane parts, was carried out. Various solutions for the difference of the central axes of the crane and crane parts of the column in the model are proposed. The results of static calculation of column elements are obtained. A comparison of the results obtained is made, an analysis of the optimal method of modeling column elements for structural schemes is performed. Based on the calculations performed and the analysis of the results obtained, conclusions are drawn.

Keywords: industrial building, I-beam, finite element method, stress-strain state, node, rod, circuit

The concept of vertical expansion of development is becoming more and more popular in Russia, especially in large cities due to the scarcity and high cost of building land. This article continues the study presented in the material on the choice of a variant of the technology for constructing an operated roof, designed to be used, for example, as a recreation area, sports grounds, landscaping, etc. The article presents the results of a comparative assessment of the technological efficiency of the operated roofs construction, arranged with a traditional and inverse arrangement of a waterproofing carpet and thermal insulation. In the study, methods for evaluating their organizational and technological solutions based on technological efficiency indicators were applied. In addition, examples the systems engineering assessment tools use is provided. Determination of the manufacturability degree for the operated roofs installation on the basis of some system-technical principles and optimality criteria when comparing different options for organizational and technological solutions. Based on the calculation of performance indicators, a set of indicators with different dimensions arises. They are used as input for aggregate analysis when applying systems engineering. This approach allows achieving internal compatibility between the elements of the system, in this case, the obtained performance indicators. The technological advantages of the inversion installation of an exploited roof, in particular, intended for landscaping, have again been confirm.

Keywords: exploited roof, vertical gardening, inversion roof technologies

The results of a study of the effect of hardening the roof of workings of small length, of arbitrary shape, with a cross section of up to 80 m2, with advanced anchoring, which can significantly reduce the displacement of soil outcrops, are presented. The analysis shows that it is not possible to completely eliminate soil fallouts; therefore, a complex of studies of a stress-strain (SSD) soil mass, reinforced with a protective screen, was carried out. Finite element modeling (FEM) has established that advanced anchoring up to 15 m long does not work effectively, since the anchors are located in the zone of soil slippage. Increasing the length of the protective screen anchors to support their ends outside the sliding prism makes it possible to increase the stability of soil outcrops in the face.

Keywords: underground construction, stresses, displacements, hardening, anchoring, modeling, finite element method

The influence of surfactants, in particular adhesive and reducing additives, on the low-temperature and rheological properties of road bitumen is considered. Tests of the low-temperature properties of road bitumen with and without the use of appropriate additives were carried out, followed by a comparison of the results. Also, in order to assess the effect of the above surfactants on the ability of road bitumen to retain its properties over time, a comparative analysis of bitumen samples subjected to the aging process was carried out. In general, the results of this study indicate that the use of surfactants can lead to an increase in the durability of road bitumen, even at low temperatures.

Keywords: bitumen, surfactant, additive, low-temperature property, durability, road, asphalt concrete, rheology, aging process, testing

In article there is considered the application of the finite difference method to plate bending problems. There are done the calculations of simply supported rectangular plate on an elastic foundation by the finite difference method and to verify the results there is done comparison with the results obtained by double trigonometric series. For more accurate results is studied the degree of discretization of the finite difference mesh.

Keywords: finite difference method, plate on an elastic foundation, Winkler model, governing differential equation of the plate, finite difference operator

The article considers the influence of seismic load with different ballistics on aboveground steel gas pipelines of various diameters in areas of possible earthquakes. The change in the proportion of seismic load to the total load acting on gas pipelines during operation is investigated.

Keywords: seismic activity, loads on gas pipelines, analysis of seismic activity, degree of seismic hazard

The article is devoted to the analysis of the possibilities of using modular home building technology. Modular construction is determined by approaches that do not follow traditional methods. The system is reduced to the assembly of prefabricated buildings from individual modules. These modular elements are usually manufactured at the factory. This helps to remove weather restrictions, reduces the risk of a shortage of labor on the spot. Placed on the foundation, the individual modules are assembled into a complete modular structure. With modular housing construction, the possibilities and choices are quite limitless. There is always an opportunity to make an individual design. In prefabricated houses, it is possible to use modules equipped with water supply, sewerage, heating and electricity systems. The article presents an overview of the advantages and disadvantages of the modular design. The advantages are listed in terms of quality, economy, time and ecology, as well as in terms of design flexibility and work safety, both during production and during installation on the construction site. The disadvantages of the modular design are also considered - complex transportation of modules requiring coordination of production and construction, the high cost of production and its typification.

Keywords: architecture, modular housing construction, module, frame buildings, ergonomics, energy efficiency, volumetric and modular design, modular construction

When designing engineering structures, the efficiency of the engineer’s work is important. The cooperation between individual programs in BIM technology is very important in this aspect, because it significantly speeds up the work and, as a result, the design process is less time-consuming. In the process of designing steel structures, the first stage is the selection of an appropriate structural solution, then numerical calculations of the model together with all assigned load cases and dimensioning of individual elements of the structure in terms of the ultimate and serviceability limit state. After selecting the appropriate sections, you can start working on the detailed drawings of a given structure. When performing numerical calculations and drawings, at least two programs should be used. The article presents the cooperation between the Dlubal RFEM numerical calculation program and the Tekla Structures building structure modeling program on the example of a steel structure floor design.

Keywords: BIM, Dlubal RFEM, Tekla Structures, steel structures, direct import, engineering structures

The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, the organizations of the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.

Keywords: management, traffic, traffic flows, pedestrian flows, technology, design, interchanges, control method, numerical model, simulation

Based on the research conducted by the authors, data on the stiffness and curvatures of reinforced concrete beams with a layer of various heights of concrete with frame structure are presented. Stiffness, curvature and deflections are given for cases of absence and presence of cracks in the tensile zone of beam. Formulas for describing changes in the stiffness and curvature of sections depending on the magnitude of the moment are obtained. The influence of the thickness of the layer of concrete with frame structure and the diameter of the working reinforcement on the change in the stiffness of the sections is established. The regularity of changing the position of the neutral axis for single and double-layer beams depending on the beam parameters.

Keywords: concrete of frame structure, stiffness, curvature, deflection, layered structures, bending moment, neutral axis

This article discusses various aspects of the design, construction and operation of shopping centers and shopping and entertainment complexes from the point of view of fire safety. Examples of existing structural and space-planning solutions that do not fall under the regulations governing fire safety, but pose a danger to visitors and staff of the shopping center and shopping mall in the event of a fire. Ways to eliminate these shortcomings are proposed.

Keywords: fire safety, children's play area, shopping-entertainment area, normative legal acts

The main reasons for the weakening of wooden structures, as well as the main requirements for strengthening wooden structures, are considered. Various methods for strengthening structures are being analyzed. Strengthening with carbon fiber is highlighted separately, the main advantages and disadvantages of this method are considered.

Keywords: analysis, causes, methods, reinforcement, wooden structures, wood, reconstruction, carbon fiber, composite, strength, deformability

As part of Sol-Iletsky Mine No. 2, it is planned to erect and set up a health resort center for the treatment of respiratory diseases. This health center will provide medical services in the therapeutic salt chambers on the first horizon (123 meters underground). For this purpose, it is necessary to use the waste horizons of rock salt (chamber workings). For the construction of the health-improving complex for safety reasons in part of underground workings, it is required to arrange a fortification. This article deals with mathematical modeling and selection of the optimal type of support for chamber workings.

Keywords: mathematical modeling, stress-strain state, SSS, rock salt, roof support, chamber workings, finite element method, FEM, redevelopment

Effective reinforcement of the coating beam, by means of the construction of a framing frame around it, implies a reasonable choice of a construction from a range of rolled metal. The frame creates a single system with the coating beam by means of tension devices, the change of forces in which provides state control. In the article, a comparative analysis of moments in a frame made of an I-beam and a special steel channel, as having potentially equal performance characteristics, is proposed for a comparative study. The research was carried out on the basis of numerical modeling by the finite element method using the Etabs software product. The result of the experiment was the transverse forces and moments determined in the newly formed system – the coating beam plus the frame – from the applied loads and the percentage of reinforcement of the beam when taking into account the frame. The array of numbers obtained as a result of the numerical experiment was processed by digital mathematical analysis.

Keywords: reinforced concrete beam, I-beam reinforcement, channel reinforcement, moment, percentage of reinforcement, load, numerical method, mathematical model, comparison of results, Etabs and wxMaxima software packages

CFD modeling seems to be one of the most accessible and accurate ways to calculate the characteristics of flow processes using computational and physical-mathematical methods in solving practical problems today. In particular, it is used to determine the parameters of the indoor microclimate. This article describes the process of modeling the operation of hydraulic heated towel rails in the bathroom of a residential building and selects the optimal configuration based on the data obtained as a result of the calculation in the STAR CCM + software package.

Keywords: CFD modeling, building hot water supply, heated towel rail, heat flow, heat transfer, heat transfer, indoor climate, thermal analysis, SolidWorks, STAR CCM+

The formation of the structural form of the roof of trihedral trusses, each of which consists of two inclined flat trusses with a common lower chord, is considered. The design of the spatial truss is made with continuous chords of a closed composite section and a triangular slanting lattice from single rolling corners. The purpose of numerical research of a span trihedral trusses is to assess its stress-strain state with variability of influencing parameters. The methodology of numerical research is based on a calculated mathematical model of a trihedral truss with the application of single loads in the knots and allows you to obtain an array of stress-strain state data, taking into account the variability of the load, which is due to the characteristics of the construction region and the features of the enclosing structure of the roof. The structure of the spatial-stem model is based on a centered geometric scheme. The approbation of the presented methodology was carried out using a trihedral truss spatial-stem calculation model. As a result of numerical research of the proposed technique, data characterizing the stress-strain state of the trihedral truss model from a single nodal load were obtained. The analysis of the obtained results shows that the presented research methodology allows obtaining structured data taking into account the variability of load values and can have practical application of the calculation results in the design.

Keywords: trihedral truss; pentahedral composite profile; direct coupling knot; centered geometric scheme; stem calculation model

The article presents the results of comparative analysis of the equations of Russian and foreign design codes for calculating the web strength capacity of I-beams with steel and fiber reinforced polymer (FRP) transverse reinforcement. It is known that the strength of the web is affected by the properties of the transverse FRP, in particular, its relatively low modulus of elasticity. When calculating the strength of the webl, both homeland and foreign design codes do not distinguish between structures with FRP and steel transverse reinforcement. To assess the accuracy of the equations of the codes, the calculation was performed on a sample made up of the results of our tests and the experiments of other authors. When calculating according to the method of SP 295 and Eurocode 2, overestimated values of the resistance of the web with FRP were obtained. The formulas for the strength of the webs, which give a significant margin when calculating beams with steel transverse reinforcement, also overestimate the resistance of beams for specimens with composite transverse reinforcement

Keywords: wall strength, I-beams, transverse reinforcement, design standards, basalt-composite reinforcement, steel reinforcement

The article provides the basics of the theoretical prerequisites for the question of the reliability of elements of wooden structures, gives the structure that forms the parameters of reliability, formulates criteria for the use of scientific research in the design and calculation of structures using wood. The calculation implementation is presented on the example of calculating the deformability of the enclosing plywood panel of the coating.

Keywords: stress, deflection, elastic modulus, stiffness, load duration fraction, bending, design resistance of wood