The article provides an assessment of the economic efficiency of a prestressed bistal beam, prestressed stretching of web. The comparison is made with a conventional bistal girder without prestressing with the same cross-section. The costs of material, design, production, transportation and installation are considered. It is taken into account that to create pre-stress, more labor costs are always needed, therefore, the manufacture of pre-stressed structures is more expensive than conventional structures. The purpose of prestressing is to reduce the consumption of steel in the fabrication of the structure. The structure of labor costs for the manufacture of structures is given. A comparative analysis of the cost "in business" of a running meter of a beam, prestressed by wall stretching, and a beam without prestressing, depending on the complexity of their manufacture, is carried out.

Keywords: thin-walled structure, bistal girder, I-beam, prestressing, stretching of web, structure weight, overhead costs, labor intensity of manufacture, cost-effectiveness, custom design, value in action

The article reproduces and supplements the experience of modeling and determining the optimal angle of inclination of the lattice with an estimate of the total lengths of the elements, the greatest forces, displacements and natural frequencies for computer models of various configurations. The possibility of using this system in civil construction with the use of volume-block technology of building construction is described. This article will be useful for design engineers involved in the design and calculation of high-rise buildings, bulk-block or modular buildings made of reinforced concrete and metal structures.

Keywords: diagrid, mesh load-bearing structures, reinforced concrete structure, metal structures, stability, computer model, high-rise buildings, bulk-block, prefabricated module

This article provides information on the possibility of using offshore wind farms to provide energy to offshore structures such as oil and gas platforms, as well as coastal communities.

Keywords: wind power plant, wind generator, offshore power plant, SIEMENS generator, offshore oil and gas facility, oil and gas field, coastal settlement

With the help of a comparative analysis by the method of hierarchies, various organizational and technological solutions for the device of hinged facade systems were considered in order to determine the most effective and rational type. The options are compared in terms of the duration and cost of construction and installation work. The comparison result is a compromise solution depending on the weight of the compared indicators.

Keywords: facade system, organizational and technological solutions, comparative analysis, duration, cost, hierarchy method

Constant climate changes, the rapid pace of development of the northern and eastern territories of our country, the areas of permafrost spread, put forward a number of relevant theoretical and applied problems for science. Soil degradation in permafrost areas entails the deformation of buildings, the emergency condition of thermal and power plants, the immersion of road sections after 2-3 years of operation in the ground of the base, the failure of the supports of power supply networks, communication lines and water pipes.

Keywords: permafrost, climate change, soil degradation, monitoring of the technical condition of buildings, operation of structures

The article presents an attempt to recreate the entrance group of a fortification located in the delta of the Don River and once belonged to the Republic of Genoa in the form of a virtual model. The publication used previously unpublished documents, which formed the basis of the proposed work. On the basis of archival materials, the authors created a three-dimensional model of the Genoese gate of the XIII century, the traces of which in the XXI century almost disappeared. From the documents found, the exact dimensions of the structure became known, as well as some architectural elements that decorated the entrance and walls inside the opening. The presented virtualvirtual model is based on measurements made during the archaeological expedition of B. V. Lunin.

Keywords: Tana, Genoese trading post, Genoa, fortress, gatehouse, fortification

The article deals with measures to preserve the ground bases of structures in a frozen state. It is shown that the methods of soil screening are cheap and do not use special equipment. These methods use different types of insulation: natural and artificial. The existing technologies of the device of thermal insulation screens on highways and engineering structures are described. It is proposed to replace polyurethane foam with extruded polystyrene foam. These materials are described and their physical properties are compared. The technology of the device of the heat-insulating coating is given.

Keywords: geoplites, expanded polystyrene, polyurethane foam, thermal insulation screen, foundations, permafrost soils, geotextiles,moss cover

The article analyzes the results of experimental studies of prestressed steel I-beams. Presented specific features of the stressed and deformed states of welded steel beams, prestressed by wall stretching and bending of the initial T-element. In the first method, the prestressing in the beam was created by mechanical stretching of the wall on a special stand. In the second method, the T-piece is loaded by external forces applied to the T-bar plate until normal stresses appear at the bottom point of the wall, equal to the design resistance of low-carbon steel, then the second belt plate is welded to the T-piece element. The results of a numerical experiment with these beams, carried out in the SP LIRA, are considered. Presented a comparative assessment of the results of numerical and full-scale tests of prestressed I-beams a similar section with bimetallic beams without prestressing.

Keywords: web stretching, T-beam bending, section asymmetry, numerical experiment, test stand, stress, bearing capacity, beam rigidity, bending deformation, local stability

The article describes the problems of modern industrial architecture of small and medium-sized enterprises. The conflict between the established design practice based on the methodology of the 70s-80s of the XX century is revealed. A method of solving the problem based on the planning rethinking of the principle of "flexible" layouts is proposed and the introduction of a new element into the structure of the enterprise – the development zone.

Keywords: industrial architecture, problems of modern architecture, flexible planning solutions, functional mobility, blocking of premises, small-scale functional zoning, industrial enterprise development zone

This article discusses the importance of timely monitoring of the technical condition of structures and buildings in general in the process of preserving cultural heritage objects. And also, using the example of the Rostov region, the article raises one of the existing organizational and technical problems of preserving cultural heritage objects – the lack of the ability to conduct timely monitoring of the technical condition of historically significant objects in the region, and the urgent need to create local organizations to monitor the technical condition of objects and prevent violations of their operation.

Keywords: cultural heritage object, monitoring, inspection, technical condition, complex technical studies, violations, operation, historical value, restoration, repair, preservation

In Russia, the legislative requirements of the municipal authorities of all regions are gradually becoming mandatory in the field of dismantling trade pavilions illegally installed on urban lands, which is why this article is so relevant. The article deals with the problems of determining the capital of trade pavilions in the judicial construction and technical expertise. An example from practical activity is given. The term "capital structure" is also considered and signs of capital are displayed.

Keywords: capital structure, construction, judicial construction and technical expertise, trade pavilions, construction expertise

During the heating period in many Siberian cities, there is a low quality of atmospheric air. One of the main sources of air pollution is the private sector, since most individual residential buildings, existing and under construction, do not meet modern standards for the thermal protection of buildings, and as heat generators they use furnaces and boilers that do not have an environmental class in terms of emissions of pollutants. Individual residential construction does not require the preparation of project documentation, therefore, each home owner independently decides on the parameters of the building, including its thermal protection. However, in the minds of ""self-builders"" there is often no understanding of how the leakage of thermal energy occurs through the building's enclosing structures and their junctions. In the article, firstly, standard solutions for insulation of enclosing structures of low-rise buildings were considered; secondly, the payback period of these solutions was determined depending on the thickness of the thermal insulation layer and taking into account the cost of additional materials; thirdly, the payback period of various solutions was compared and the most quickly recouped ones were selected. In the course of the study, it was found that the costs of measures to strengthen the thermal protection of the enclosing structures of an individual residential building can be compensated by a future reduction in the consumption of brown coal or other energy carriers, which will also reduce the emissions of pollutants into the atmosphere. At the same time, the greatest energy-saving effect is achieved from the insulation of the attic floor and the underground space, since it is not required to use expensive facing coverings as on facades. The results of the study can be used as a recommendation when choosing the optimal thickness of thermal insulation when strengthening the thermal protection of the enclosing structure with the desired payback period.

Keywords: energy efficiency of buildings, energy audit of buildings, heat loss in low-rise buildings, energy saving measures, reconstruction of buildings, problems of coal-fired heating, reduction of air pollution, reduction of CO2 emissions

Blasting operations are often the only way to prepare the material for the recess for laying roads and railways in the rocks. Explosive loosening is also used to extract stone as a building material. Field testing is costly and often dangerous. Therefore, it is necessary to first conduct a series of experiments on the model and find out the conditions for ensuring good quality loosening of rocks. In order for the results of model tests to be transferred to nature, a similarity between model and specimen is required. The approximate similarity is achieved by the equality of the similarity criteria for the model and specimen. The characteristic similarity criteria are obtained by analyzing the physical quantities inherent in a mechanical system using the theory of dimension and similarity. The received criteria are presented in the classical form. These are the criteria of Strouhal, Froude, Cauchy and Newton.

Keywords: explosive loosening, rock material, deceleration interval, similarity criterion, modeling, rock density, model, specimen, expansion height, dimensionality, physical quantity

The process of finding the calculated lengths of the elements of a cross lattice using the displacement method in the case when both bars are not interrupted and when one of the bars is interrupted and overlapped by a gusset is considered. New formulas of the displacement method are proposed for finding the support reactions of an element having a spring fixation at one of the ends. A formula is proposed that allows you to determine the spring stiffness, with the help of which the operation of the connecting strip is simulated. A comparison is made of two calculation options: using the usual formulas of the displacement method and using the proposed new formulas. The calculation showed good convergence of the results with a significant simplification of the calculation process in the second case. A comparison of the calculated lengths obtained with the instructions of the current sets of rules is given. The possibility of adopting a more economical section when determining the calculated length by means of the displacement method is noted.

Keywords: estimated length, cross lattice, stability, critical force, truss

The possibilities of using advanced software for effective analysis and design of building structures are currently being explored. Rapid assessment of the state during design, assessment of the ability to resist any of the loading environments. The finite element method possesses these qualities. In this article, a nonlinear FE analysis of cold rolled steel beams Z-profile under bending load using ANSYS software. The bending resistance of two types of beams is compared, a Z-beam with hollow flanges and a Z-beam with solid flanges. A beam with hollow flanges exhibits better deformation characteristics than a solid one. Based on the analysis, the following conclusions are drawn: The proposed hollow flanged element shows better resistance towards deformation; Since the hollow section follows a single profiled failure pattern the point of failure is extended; The stiffness of hollow flanged Z section is nearly four times greater than that of solid flanged Z section.

Keywords: efficient analysis, finite element method, Z-profile, deformation characteristics, nonlinear FE analysis

The article discusses the constructive and conceptual solutions associated with the implementation of the main devices of the central air conditioner, working in conjunction with the chiller. The peculiarity of the implementation of these devices is dictated by the use of solar energy. The receivers of solar energy are solar collectors, in which the heating medium is heated, which is used as a heat source in the chiller generator.

Keywords: solar energy, central air conditioner, chiller, absorption refrigeration machines, vacuum solar collector

Various options for connecting wooden structures are described. Examples of the use of various compounds, the most common today, are described. The advantages and disadvantages of such compounds are analyzed, and the technical characteristics of the elements used are given. Advantages and disadvantages of joints of wooden structures with the use of composite materials are described.

Keywords: wooden structures, joints of wooden structures, analysis, mechanical connections, comparison, load, strength, nagel, cool connection, mating, toothed plates

The current situation in the world related to the pandemic and the new rules of social distancing allowed us to identify the main problems of modern formation of the maternity institutions architectural environment and showed the need for their spatial modernization, taking into account the flexible planning structure. The article discusses individual approaches to creating a comfortable therapeutic environment that promotes social distancing. An «architectural and spatial approach» is proposed, which changes the boundaries of spaces in the following areas of the maternity facility: «entrance», «reception of women in labor», «area for relatives and hospital visitors», «delivery of newborns», «consultations» in the Polyclinic Department of the maternity hospital. The second, «environmental approach», is based on changing the scheme of communication and environmental situations in the internal environment of the maternity facility: the interior environment turns from public to autonomous.

Keywords: maternity hospital, perinatal center, therapeutic environment, social distance, adaptation, modernization

Creep is a slow plastic (irreversible) deformation of a product under the action of stress created in the material. This article discusses the creep of polymer products. The creep of a material is characterized by the experimental dependence of the deformation resulting from a fixed load on time.

Keywords: material deformation, elastic deformation, highly elastic deformation, polymers, viscous deformation, plastic deformation

The article shows the current problems associated with the development of the northern part of Russia. Large deposits of ore minerals and hydrocarbons are located in the northern regions. The severe climatic conditions of these regions and the difficulties of construction on permafrost soils are noted. Special attention is paid to the relevance of the issue of soil stabilization. The analysis of the degradation of permafrost soils is carried out on the basis of statistical data on the change in the average annual temperature recorded by the Salekhard weather station. It is concluded that when the thawed base is planted, the destruction of structures and man-made disasters are possible. The methods of ensuring a stable frozen state of soils during seasonal thawing are considered. The types and classification of seasonally operating cooling devices are presented. The principle of operation of the presented devices, the scope of application of each type of seasonally operating cooling devices is given.

Keywords: soil, heat stabilizer, heat carrier, cryolithozone, foundation, foundation, bridge construction, monitoring, condensation, freon, expanded polystyrene

The object of the development is an experimental installation with pulsed circulation of the coolant in the main circuit for its use as a hydraulic drive of a diaphragm pump used for pumping liquid in the secondary circuit, which increases the energy efficiency of the pump drive for small-scale energy facilities. An installation with pulsed circulation of the coolant with a diaphragm pump was developed, assembled and tested on the basis of a new design of the shock unit with a cam profile, which makes it possible to create an acceleration of the flow at the pump suction. As a result of the experiment, we obtained the dependence of the volume of the pumped liquid on the frequency of operation of the shock unit.

Keywords: energy efficiency, diaphragm pump, shock unit, pump drive, cam, fluid flow, fluid pressure, oscillation frequency

The method of conducting an expert examination to determine the level of impact noise of the floor covering is considered, the features of the results of the study of the sound insulation values are reflected.

Keywords: impact noise, impact noise level, expertise, sound absorption coefficient, octave band, third-octave band, geometric mean frequency

This paper reports on the results obtained on the diagnostics of a steam pipeline of a thermal power plant; it analyzes the effect of thermal fatigue on the structure and properties of the 12Kh1MF steel and possible reasons for the emergency destruction of steam pipeline elements before the exhaustion of economic life. Ultrasonic testing and additional heat treatment are proposed to be used for the detection and elimination of structural inhomogeneity in the metal. The applicability of statistical technique to analyzing data on the loading history of a steam pipeline is studied, which enables us to evaluate the damaging effects of loading cycles and to develop a plan of preventive measures, as well as to increase the accuracy of predicting the residual life of steam pipeline elements.

Keywords: metallic structure, diagnostics, degradation, steam pipeline, thermal fatigue, microstructure, mechanical properties, residual life

Permafrost occupies about 25 percent of the world's area and spreads across the north of America, Europe, Asia, as well as the islands of the Arctic Ocean and Antarctica. In Russia, a considerable part of the population lives and works in the regions of the Far North, where mining is rapidly developing in conditions of permafrost. This is where the erection of the foundations is an important issue.

Keywords: pile foundations, permafrost, drilling, oil production, land, territory, deformations, soil, installation, screw piles

Reducing energy consumption in the design, installation and operation of engineering networks is implemented in the process of implementing investment construction projects. An energy service contract, like any economic agreement, requires a feasibility study. When strengthening the thermal protection of a building, it is necessary to determine both the design of the fences and translucent structures, and the payback period of the investment. The objective of the research is to develop and analyze a mathematical model of heat losses depending on the characteristics of the resistance to heat transfer of walls, windows and balcony doors. Classical dependencies do not allow applying standard mathematical analysis procedures. It is proposed to use a power function that assumes the availability of differentiation. The paper substantiates the form of such a function and provides an extended analysis of the effect of changes in the resistance to heat transfer of building structures on the transmission heat losses of a building, which allows arguing for the adoption of optimal technical and economic decisions.

Keywords: energy-saving construction project, thermal protection of buildings, indifference curves, mathematical model of heat loss