Modern Problems in Construction

One of the main problems in the operation of ventilation and air conditioning systems is the low efficiency of using low-potential heat emitted together with the fluxes of exhaust gases and ventilation emissions from the premises of industrial enterprises, public, administrative, residential buildings and structures. To solve the above problem in modern ventilation and air conditioning systems, heat recuperators and heat exchangers of various designs are used, while plate recuperators are the most effective and widespread. The main characteristic of a plate heat exchanger is the amount of heat transferred through a unit of heat exchange surface area at a temperature difference—the heat transfer coefficient. In order to increase the efficiency of heat exchange of plate heat exchangers, various methods of intensifying the heat transfer process are used, one of which is the installation of turbulators of various shapes and types of their location. This article presents the results of experiments conducted on a complex multilayer plate heat exchanger with integrated Peltier elements and cylindrical turbulators installed in a staggered and corridor arrangement, which allows to utilize low-potential heat while simultaneously obtaining thermoelectricity. The aim of the work is an experimental study of the temperature regime in the intersectional space of a complex multilayer plate heat exchanger during the utilization of waste gas heat and ventilation emissions for heating supply air and associated production of thermoelectricity. An original design of a complex multilayer plate heat exchanger is proposed. Experimental studies have been carried out at a fixed coolant velocity and air flow temperature, graphs of the dependences of thermoelectricity generation on the operating time of the experimental installation have been constructed. Due to the use of cylindrical turbulators, turbulence of flows increases, as a result of this, the heat transfer process is intensified with the associated production of thermoelectricity. The high efficiency of using a complex multilayer plate heat exchanger, turbulators with a staggered arrangement in comparison with a corridor and without their installation in the design of the cooling system has been established. The resulting electricity can be used for additional heating of the supply air or to ensure the autonomous operation of the automation and control system of the ventilation unit.

The problem of providing land plots for the construction of specific real estate objects existing in the modern world without taking into account the potential impact of these objects existence on the state of the urban environment and, as a result, on the possibility of satisfying the rational needs of city residents has led to the unjustified placement of some shopping centers on the modern cities territory. As a solution to the problem, this article proposes to provide land plots for construction based on calculating the realizability of the functions of a biosphere-compatible city in the territory after the construction of a specific real estate object on the requested land plot.

The problems of non-equilibrium and nonlinear processes in the evaluation of reinforced concrete structural systems robustness potential in ultimate states are considered. The definition of concept of “robustness exposition” is given for a quantitative assessment of the robustness potential. A calculation model based on the generalization of the well-known classical relationship between the current relative deficit change rate of the reinforced concrete stress–strain state with respect to each fixed time value is proposed to describe in time non-equilibrium processes of structural materials force resistance depending on the mode and level of loading. On the basis of the linear creep theory, aging materials, an algorithm was developed to determine the measure of creep, corrosion-damaged concrete and reinforced concrete and to determine the parameter “robustness exposition” of a reinforced concrete statically indeterminate structural system, taking into account non-equilibrium and nonlinear processes of its deformation in time. An example of a single-span rigidly clamped reinforced concrete beam calculating the robustness potential from the position of a special limiting state criterion is considered.

The paper focuses on the fact that today's modern digital technologies are a productive tool in the field of energy efficiency and energy conservation of thermal energy complex of the Russian Federation. The paper analyses different methods of hydrodynamic calculation of heating systems. The main task includes the analysis of existing hydraulic regime models to determine the prospects of the need to refine the techniques to build digital twin systems. The results of the calculations of the hydraulic regime of the heating systems are presented by summarising the existing mathematical description approaches, the convergence of which was assessed by comparing the values obtained as a percentage of the adopted basic calculation method. The authors note significant discrepancies in the results obtained, which are explained by the assumptions adopted in a particular method in order to simplify calculations and save time in the course of their implementation. It is suggested to use in calculations the values of local resistance coefficients according to the known dependences presented in scientific literature, where the influence of liquid movement mode on the value of local resistance coefficient is taken into account. It is pointed out that the concept of digital twin construction requires development and validation of mathematical models with high level of adequacy. In this connection it is concluded that the mathematical description of thermal and hydraulic regimes of heating systems requires clarification and additional theoretical and experimental research.

The article is devoted to the development of a system for optimal planning of the trajectory of the movement of construction machines, taking into account the deterioration of the technical condition of their drives. A fuzzy model for optimizing the movement of a vehicle takes into account the technical condition and the load on the driving wheels. The model allows, based on the results of the assessment of the technical condition and load, to select the required operating mode for each drive: four-wheel drive; front-wheel drive; rear-wheel drive; termination of operation. To continue operation in the selected mode, the criteria for the optimal trajectory of the vehicle are formulated, taking into account the length of the trajectory, the number of right and left turns and the technical condition of the drives. Three analytical solutions of the optimization problem are given. Possible trajectories of movement are built and the number of turns of the car is calculated. The same problem was solved using genetic and ant colony algorithms for the same input data. A comparative analysis of the obtained results was carried out.

Energy-efficient methods of creating a microclimate of premises using renewable energy sources are considered. The feasibility of using heat recuperators of exhaust air is shown. Various types of recuperators are considered, their comparative characteristics are given. It has shown that the proposed calculations of their effectiveness give overestimated results, that does not correspond to reality. This work has developed a system for creating a microclimate of premises using an air heat pump of the Air–Water type. The use of such installations in areas with a cold climate is possible only with the use of the MOVEBIT de-icing system developed by us in the form of magneto-constrictive transducers installed on the surface of the heat exchanger of the evaporation unit. The microclimate system includes two evaporation circuits. The primary circuit works for heating using outdoor heat. The second evaporator connected in series to the first one is located in the exhaust air heat recovery circuit of the ventilation system. Heat exchanger of evaporation unit is made of aluminium and has certain shape, which is most favorable for de-icing. The tests showed an increase in the overall coefficient of performance (COP) of the complex heat pump installation by 20%.

The composition and characteristics of the developed wood-gypsum composite material of the optimal composition were investigated. The wood-gypsum composite material can be used both as a finishing material for interior finishing and as a repair composition. Optimal is the following composition by weight: 45% gypsum grade G16, 16% second grade pine sawdust with a fraction of 5 mm, 39% water The moisture content of the composite material was determined using a gravimetric measurement method based on the extraction of moisture from the material and the calculation of its mass fraction. The moisture content of the wood-gypsum composite material is 26.3 ± 1.2%. The study was conducted on a moisture meter AND ML-50 instrument. The specific surface area was measured by the Brunauer–Emmett–Teller (BET) method using a highly efficient gas absorption analyzer with three micropore analysis stations and four specialized built-in ports for sample preparation (degassing). The specific surface area of the material was 9.9 m2/g. Elemental analysis was also performed, which makes it possible to quantitatively and qualitatively establish the composition of the composite material. Elemental analysis showed that the developed wood-gypsum composite is more than 98% composed of Ca and Sx.

The purpose of this work is to study the properties and optimize the composition of cement composite materials containing special modifying additives—sodium sulfate and Neolith P8800 redispersible powder. To achieve the goals set in the work, the following methods were used: the method of mathematical planning of the experiment, standard methods for testing materials for fungus resistance, strength; mixture composition optimization method. Modifying additives are introduced into cement composite materials to improve consumer properties. Samples of cement composites containing various amounts of additives were made. Tests were carried out for fungus resistance and strength of control samples and samples with additives. An increase in the fungus resistance of composites with the introduction of additives has been established, which allows the use of products and structures made of them in adverse operating conditions in the presence of a biologically active environment. A decrease in the strength properties of composites with additives was revealed. The problem of optimizing the composition of composites was solved with the identification of the concentration of additives at which the material has fungus resistance, and the strength properties decrease slightly, up to 15% of the level of compressive and bending strength of the material without additives. The results of the study serve to determine the composition and concentration of components in the manufacture of dry building mixes.

The stationary axisymmetric flow of drilling mud under the action of a constant pressure drop created by a drill pump in a horizontal pipeline is investigated. The relevance of the proposed work is determined by the fact that the quality of drilling mud is one of the most important components of the technological process of drilling oil wells. In this regard, there is a need to develop a formulation of a dispersed system, which is a drilling mud, which allows for effective cooling of the rock-destroying tool, high-quality removal of sludge to the surface in compliance with the requirements for solutions, with minimal material costs. The purpose of this work is: to establish a relationship between structural parameters and hydraulic resistance of the fluid flow within the framework of the Ostwald-de Waele rheological model; to study the stress–strain state of the model medium in a stationary, axisymmetric flow; to establish a relationship between the average flow hydrodynamic characteristics with its viscosity parameters. Analytical dependences of the distribution of effective viscosity and axial velocity of the medium flow are obtained. The dependence of the flow rate of the model medium on the magnitude of the pressure drop, as well as the distribution of the dynamic shear stress along the pipeline section, are determined.

A new method for determining the thermal fluctuation constants of the generalized Zhurkov equation is proposed. The method is based on the experimentally established dependences of the obtained thermal fluctuation constants on the coordinate of the pole point and the limiting temperature. The choice of the subject of the study is justified, methods of conducting experiments and processing experimental data are given. Solid polyvinyl chloride plates were selected as the sample material for the study, which were broken by transverse bending on a six-position bench. To increase the reliability of the obtained results, the static processing method was used according to GOST R 8.736-2011. According to the obtained experimental data, graphs were plotted in coordinates «lgτ - σ». A reference beam and the corresponding reference constants are proposed, as well as a system of coefficients necessary for finding the thermal fluctuation constants of a material on the basis of reference constants. To verify the adequacy of the developed technique, the thermofluxtution constants of the generalized Zhurkov equation for the decorative protective plate on the polyester resin binder were determined by the reference beam method, which were compared with values with constants for this material obtained by the graphical and graphoanalytic method.

In connection with ensuring the necessary reliability in the operation of both the building and the structure as a whole and its elements, as well as the need to prevent progressive collapse under special actions, it is important to develop effective calculation models for analyzing the strength and deformability of the most used structural material—concrete and reinforced concrete. The article summarizes the working prerequisites and hypotheses necessary for the construction of general physical relationships (relationships between stresses and deformations) of a complex-stressed reinforced concrete element. The criteria for assessing the strength and deformability of reinforced concrete under triaxial and biaxial stress are presented. When constructing the calculation model of the resistance of this composite material, the physical non-linear work of concrete was taken into account based on the theory of plasticity by G. A. Geniev, as well as its anisotropy in the form of reinforcement coefficients and other factors.

The purpose of this work was to study the morphology and particle size distribution of new tungsten-free hard-alloy powder materials produced by electro erosive dispersion in an oxygen-containing medium (distilled water). To produce new tungsten-free hard-alloy powder materials, an experimental laboratory setup for electro erosive dispersion was used. The analysis of the grain size composition of electro erosive tungsten-free hard-alloy particles was carried out by means of an Analysette 22 Nano Tec laser particle size analyzer. The method of scanning electron microscopy using a QUANTA 600 FEG microscope was used to study the morphology of the experimental powder material. The results of the analysis of the particle size distribution of electro erosive tungsten-free hard-alloy particles showed that the particle size ranges from 0.372 µm to 65.5 µm. It is shown that the average size of the particles obtained in distilled water is 41.63 μm. The study of morphology showed that in the process of electro dispersion of metal waste, the particles that ejected from the electric discharge channel in molten form crystallized very quickly. The process of rapid crystallization of the molten material in a liquid working medium contributes to the formation of particles of the correct spherical and elliptical shape.

The purpose of the work was to study the phase and elemental compositions of new tungsten-free hard-alloy powder materials produced by electro erosive dispersion in an oxygen-containing medium. To produce new tungsten-free hard-alloy powder materials, an experimental laboratory setup for electro erosive dispersion was used X-ray spectral microanalysis (elemental composition study) was carried out by means of a QUANTA 600 FEG scanning electron microscope with a built-in EDAX analyzer. X-ray diffraction analysis (the study of the phase composition) was carried out using a Rigaku Ultima IV X-ray diffractometer. The results of X-ray diffraction analysis and X-ray spectral microanalysis of the new electro erosive tungsten-free hard-alloy powder materials obtained in an oxygen-containing medium showed that the main elements are Ti, Ni, C, O, Mo, and the main phases are TiC, MoNi3, Ni2O3, Ni, and Mo.

The effectiveness of using composite materials as external reinforcement systems on full-scale structures of reinforced concrete beams of industrial buildings, aimed at increasing their bearing capacity are substantiated in the article. It has been established that the strengthening of non-prestressed bending reinforced concrete structures with composite materials based on carbon fibers leads to an increase in their bearing capacity, and the recommended technology for their reinforcement with composite materials is given. The object of study in this work is the reinforced concrete structures of the beams covering the sludge pool of the cement industry with non-stressed reinforcement before and after reinforcement with composite materials. The subject of the study is the bearing capacity of reinforced concrete structures reinforced with composite materials of the sludge pool cover beams. The purpose of the study is analyzing and evaluating the technical condition of the supporting structures in the sludge pool, determining the bearing capacity of reinforced concrete structures reinforced with composite materials, calculating and justifying the external reinforcement of carbon fiber reinforced concrete crossbars of the sludge pool cover.

In various industries, technological processes often occur, characterized by the release of dust into the working area. To maintain the required air parameters in terms of dust content in industrial premises, it is necessary to use a set of systems, including an aspiration system, a centralized vacuum dust removal system and general ventilation. The efficiency and performance of the above systems are interrelated, but the aspiration system is decisive. The aspiration shelter, which is the most important element of the aspiration system, localizes the source of dust emission. Seals are used to prevent the entry of dust from the aspiration shelter into the area of the working area, as well as to minimize the volume of air removed. In this work, analytical studies of methods for determining the suction and the amount of air entering the aspiration shelters through leaks were carried out, 3 characteristic approaches were proposed to determine the magnitude of the suction, based on the degree of tightness of the aspiration systems.

The article considers the variable definition of wind loads on a building. In order to determine the wind load on the building, various options for setting the wind load were considered, taking into account the standards of various countries. 4 schemes were considered. The first and second determination schemes are carried out taking into account the provisions of the Russian standard SP 20.13330.2016, the third and fourth schemes in accordance with the Load Code for The Design Of Building Structures, GBJ 9–87. As amended by GB 50,009–2001 from 2006. To select the load application scheme in the design model of the building, the total (for the entire length) aerodynamic coefficient in the direction of the vertical axis was determined. According to the results of the study, the scheme of action of the wind load corresponding to the highest load value was determined. It is also noted that more accurate aerodynamic coefficients can be obtained from the results of model aerodynamic tests conducted in a wind tunnel.

The aim of the work is to study the possibility of the influence of fiberglass additives on the physical, mechanical and strength characteristics of concrete. Concrete with the addition of cullet and plastic as a fine aggregate is considered as an object. In modern construction, research works aimed at studying high-tech concretes using recycled waste are of the greatest value. The practical significance of the study lies in obtaining concretes with improved characteristics using municipal waste, which will increase the efficiency of processing industrial waste and reduce their harmful impact on the environment. The analysis of the properties of concrete mixture and concrete using cullet and plastic as a filler is carried out. The analysis of the mechanism of influence of additives made of glass and plastic on the properties of concrete is carried out. Recommendations for the production of concrete using additives made of glass and PET-flex as a fine aggregate have been developed. An experimental plan was developed, the composition of the concrete mixture was selected and tested, natural sand was used as a fine aggregate for the manufacture of concrete, bituminous glass was crushed using a cylinder and a plunger on a hydraulic press to a fine fraction as a cullet. Based on the experimental data obtained, graphs of the dependence of the strength of concrete on the amount of PET-flex filler, the dependence of the strength of concrete on the amount of cullet were constructed. The analysis of experimental data with determination of the greatest ultimate strength of concrete is carried out. It was found that glass and plastic waste can be used as additives to concrete, since the strength of these concretes is comparable to the strength of conventional concrete.

The nodes of the reticulated vaults with metal connections provide a one-way connection of the jambs in the nodes and the transfer of forces only with compressive longitudinal forces in the jambs. With some regulatory loads, a nonholonomic state occurs, in which a certain zone in the grid is excluded from operation. Based on the research of the design solutions of the reticulated vaults, the basic principles of the shaping of these structures were derived and the task of studying the closed reticulated vaults with the reinforcement of jambs with prefabricated tapes was set.

The research is aimed at studying methods for determining the strength of concrete, taking into account the effect of anti-icing agents on it. The focus of the study considered in the article is aimed at determining the patterns and mechanisms of joint work of concrete and chloride reagents that prevent the formation of ice on the body of concrete structures at the time of strength gain. In the course of the study, formulas were considered that determine the strength development of the samples under study in the context of the joint work of the above materials. Next, the coefficient of influence of anti-icing chemical additives on concrete structures was determined. The scientific novelty of the work lies in the determination of the physical and chemical mechanism that explains the causes of the destruction of concrete and its components under the influence of anti-icing reagents, as well as the identification of the main classification features of chemical de-icing agents by the nature of the aggressive effect on concrete and its components. As a result of the study, experimental studies of nine concrete samples were carried out under the influence of various conditions that affect the strength characteristics and durability of the material, and a method for calculating concrete exposed to an aggressive chloride environment was developed.

This article presents a theoretical study of the functioning of an experimental installation of a complex air heater designed for waste gas heat recovery. The resulting heat is then partially used to maintain the required temperature of the incoming supply air. A variant of air flow control during ventilation of premises along with the use of the resulting excess heat according to the “smart home” scheme is considered. At the same time, the transients that inevitably arise during the operation of the studied structure are taken into account.

The practical significance of the study is increasing every day, because human’s life has changed a lot with the advent of electrical appliances and electrical equipment. Their functioning requires more and more energy, which, unfortunately, has negative properties that affect the human’s body. Based on the analysis of the results of the International Project on Electromagnetic Fields, the World Health Organization (WHO) concluded that there was insufficient research on the results of the negative effects of prolonged low-level exposure to extremely low frequency electromagnetic fields and formulated recommendations, including the need to continue research to determine the negative impact on human health and ways to reduce the levels of exposure to electromagnetic fields during construction new structures. The relevance of the direction is determined by the need to develop monitoring and ways to improve the protection of the environment and people in urbanized areas near power lines of various voltage classes, which is important for ensuring the sustainable development of human settlements and protecting people from the negative effects of electromagnetic pollution of the urban environment.

The paper considers the relationship between the dynamic and static parameters of circular isotropic plates under various boundary conditions. The studies of the plates were carried out under static and dynamic loading, taking into account the variability of the thickness. The authors established the relationship between the maximum deflection and the natural frequencies of the transverse vibrations of the plates, and assessed the matching of the coefficient K obtained by numerical studies with its analytical one. The curves for the frequencies of free vibrations and deflections under the static load and the change in the coefficient K depending on the thickness of the plate and boundary conditions were plotted. Studies showed that the coefficient K complies within 5% of the dependence of Professor V.I. Korobko only when the ratio of the thickness in the center to the thickness on the support t2/t1 = 60/50 < 1.2 for both support schemes. This is due to the fact that formula (16) was derived for isotropic plates with constant thickness and the distribution of mass evenly over the entire area of the plate leads to a significant error already at the stage of a small difference between the thicknesses at the support and in the center. With a thickness ratio t2/t1 = 100/50 = 2, the difference between the K coefficient and the analytical one is about 16%.

One of the complex and difficult to formalize multi-criteria tasks when placing objects in an urban environment is making decisions about their placement, it is advisable to use scientific methods of system analysis and decision theory to solve it. Due to the large amount of open and accessible information for the analysis and active development of geoinformation systems, it became possible to use this information to solve various urban planning tasks when placing objects of any purpose, from residential to industrial facilities and organizing information support for decision-making when placing these objects. An urgent task for the authorities and self-government currently in the field of urban planning is the development of tools and methods that are based on information processing and that can be implemented as part of a decision support system.

Currently, universities have a significant impact on the environment due to high energy consumption, intensive transport, large amounts of waste, high consumption of materials and intensive development of buildings and structures. The purpose of this study was to determine the key indicators for assessing the sustainable development of the university campus when choosing its spatial organization and functional planning. Sustainable development is the most important social problem. In recent years, many scientists have proposed to solve this problem on the basis of university communities, since they are leaders in the field of education, research and innovation. The different researches connected with questions of stability of territories of campus of that have been conducted as the universities can aim at creation of steady campuses. Options of interaction of the city with arrangement of functional zones of campus based on results of quantitative and quality expert standard have been revealed. Depending on the obtained data options of transformation of the university and its adjacent territory have been offered. The main advantages and shortcomings of each of options of the space organization are revealed. The road map on making decision for town-planning placement on the city of the innovation educational environment is created.

This paper addresses the development applications which were granted planning consent for the construction of a tourist complex along the side of Ramla l-Ħamra valley—the clay slope beneath the mythical Calypso Cave in which Homer’s Odysseus was allegedly held—a unique site of cultural and ecological significance. A third-party objector set up SaveRamla, an environmental, non-governmental committee, to challenge these applications. Once granted, this multi-million euro project was widely supported by the national planning and environment regulator and given significant coverage on state media, including a debate on a prime programme. Based on planning legislation, the third-party objector proved that the outline permit on which the full permit was grounded contained false, misleading or incorrect information which had material bearing on the issuance of same. Both permits were subsequently revoked, a decision confirmed at the appeal stage. The relevance of this case study to contemporary literature on development planning is outlined. It concludes by arguing that (i) development planning history is imperative to document the evolution of the planning process over time; (ii) incorrect declaration of ownership is sufficient for revocation of planning consent; and (iii) incomplete application leads to a decision that is informationally disabled.

The object of the study is the water heating network of a residential area of the city. According to the development plan, it is planned to build 9 residential buildings, and the first stage of construction, consisting of 5 houses, has already been implemented. The remaining buildings will be commissioned one per year. The article discusses the issue of an expedient option for the construction of a water heating network, taking into account the development of its configuration when connecting new buildings. The problem is the fact that the heating network of the first stage of construction was designed without taking into account further development, i.e. it is intended to supply the estimated amount of heat for only five buildings. To solve the problem, water heating networks of promising development were designed. When connecting buildings of the second and subsequent stages of construction to the existing network, the flow rate will increase, and consequently, the hydraulic resistance, pressure losses and energy costs for fluid transportation will change. Based on the hydraulic modeling of the heating network, taking into account the input of all construction stages, the cost estimate for the costs of pumping the coolant and the project for the reconstruction of the existing network with an increase in throughput, an expedient option for building the network was determined.

Concretes containing dispersed fillers, reactive rock powders, microsilica and micro-hydrated kaolins are the object of research. The structural topology of such materials is predetermined by the activity of the dispersed filler. The unstable nature of the disperse systems, due to the high free surface energy, was used to increase the adhesion of cement to stone materials. Directional control of structure formation of reactive powder concretes is achieved by triboelectrification providing creation of transition layer on the surface of mineral material which interacts well with both cement and mineral substrate. An experimental research method based on a laboratory apparatus of a vortex layer is presented, which allows to form a triboelectric effect on the surface of fine-grained fillers. To break the aggregating effect of electromagnetic forces at the first stage of preparation of cement mortar for mixing cement with microfillers used energy-saturated high-speed mixers, and at the second stage for mixing cement composition with sand used traditional fillers.

In recent years, due to the increase in design loads in operated buildings, there is a need to strengthen their load-bearing structures. The use of high-modulus composite materials contributed to the further development of reinforcement methods. The analysis of the works related to the composite reinforcement of reinforced concrete bendable structures showed the need for experiments with a variation in the ratio of the length of the composite reinforcement to the calculated length of the element. This paper presents a preliminary calculation and selection of options for strengthening reinforced concrete bendable elements, including their inclined sections, for further field experimental studies using normative methods. Reinforced concrete beams made of concrete of strength class B15 were selected as the studied samples. The reinforcement is made in the form of a flat frame using rods of classes B500 and A400. Composite reinforcement is made using SikaWrap carbon tapes. The location of the breakage of the composite reinforcement in the stretched zone of the element is determined when plotting the load-bearing capacity of the non-reinforced element and the bending moments from the maximum possible load of the reinforced elements. An increase in the bearing capacity may lead to a change in the pattern of destruction of the sample, which requires additional calculation and design of composite reinforcement of inclined sections of the element.

In most of the world-famous computing complexes, when designing reinforced concrete structures, is not taken into account the current development of a finite element model, where it is necessary to adequately take into account the nature of the development and opening of cracks in them. The criterion for the disclosure of cracks in reinforced concrete structures is carried out using the achievement of completely different criteria. Completely different criteria should be used when analyzing the appearance and development of discrete cracks for modeling discrete cracks, taking into account the effect of violation of the discontinuity of concrete and the reaction of reinforcement from the mechanics of destruction of two elements and the development of cracks in reinforced concrete. The physical essence of which is the additional deformation effect of the reaction of reinforcement and concrete in the form of an ellipsoid for an alternative kinematic crack, from a universal two-console element in reinforced concrete. At the same time, in the stretched area of concrete for the distance between cracks and the width of the opening has in these local zones adjacent to the crack adhesion and importantly compressed concrete tensions. A classification of the basic spatial cracks in spatial reinforced concrete composite structures is constructed for discrete levels,—cracks that develop to zones of concentration of geometric, force, deformation loading or the inter-environment region, where the full picture of various types of cracks. Based on the basic cracks, a complete scheme of spatial cracks is applied by finding adjacent cracks with the involvement of the deformation criterion of their formation and the method of finding the extremum of the function of many variables using Lagrange multipliers. Nevertheless, the method of modeling discrete cracks, including using most of the world’s well-known, has not been developed by the intelligence of computing complexes. The development of spatial cracks is carried out on special bilinear surfaces. Then approximating spatial finite elements are inserted into them, which are “expanded”, modeling a spatial crack, the disclosure of which is set in the form of a deformation effect, taking into account the effect of reinforced concrete continuity violation. When solving the inverse problem of determining the width of crack opening, the deformation effect is not set, and with the help of “stitching”, only the presence of a gap of the minimum possible width is modeled, its opening under appropriate loading and determines the width of crack opening as the divergence of the banks of this gap. The article considers the pairs of finite elements adjacent to such a crack from opposite sides—a special calculated two-element console model. These pairs are considered in two states: before their “stitching” and after their “stitching”, taking into account the deformation effect and the effect of breaking the continuity of concrete. To find the level distance between cracks and the width of their opening from a reinforced concrete structure, which allows determine the desired parameters, tools or modules of the LIRA program.

Although the progressive collapse has a small probability in economically developed countries, it can lead to catastrophic consequences. Therefore, this paper is aimed to experimental and numerical investigation of impact parameters on the reinforced concrete frames under scenario of sudden column removal. As well as it provides the analysis of the failure mechanisms of the frame under consideration, and substantiation of the criteria for assessing these failure mechanisms. For the purposes of the study, a two-story reinforced concrete scaled frame was designed, manufactured and tested. A nonlinear dynamic and quasi-static analysis of reinforced concrete frame have been performed using finite element bar models both of the structure and leverage loading system. Numerical and physical modeling of an accidental impact such as sudden removal of the corner column of the shows that the exhaustion of the load capacity of eccentrically compressed column of a structural system can be caused by the stability failure.

Buildings are responsible for about 40% of all energy consumed in Palestine; therefore, buildings are responsible for most greenhouse gas emissions. It’s necessary as the first step to developing the building sector in Palestine to be an energy-saving is to quantify the amount of embodied energy and the corresponding greenhouse gas emissions releases (CO2 equivalent) associated with each stage of the building life cycle; therefore, the result can be used to determine the stages and activities that need improvement. In this study, we’ve done the life cycle analysis of embodied energy and greenhouse gas emissions (CO2 equivalent), as well as the estimated cost of emissions for the typical building in Palestine. It’s found that 73% of energy consumption and 82% of greenhouse gas emissions happen during the operation phase. The construction phase takes 45% of the life-cycle cost. The embodied energy is about 40 GJ/m2, and greenhouse gas emissions equal 3.9 t/m2.

The collapse of building objects during design, construction and operation is present throughout modern civilization. This article studied in detail the features of the exhaustion of the bearing capacity and the nature of the destruction of four series of experimental studies of monolithic reinforced concrete frame structural systems, which differ in the nature of the destruction of the sections (brittle or plastic), as well as the use of such methods of protection against progressive collapse, such as prestressed elements and indirect reinforcement. As the initial prerequisites for the calculation analysis, a diagrammatic calculation method was used, using the actual static-dynamic parameters of the “strain stress” diagrams for reinforcement and concrete, adopted in the current standards for the design of reinforced concrete structures. When assessing the nature of the destruction of the supporting sections (localization of cracks and the depth of their development), a satisfactory convergence with the accepted model of static-dynamic deformation of structural materials adopted for the calculation analysis was established. The considered and experimentally tested technical solutions make it possible to implement such stiffness characteristics of the design scheme, in which energy dissipation occurs without disturbing the geometric variability of the building’s supporting system.

To increase the protection of monolithic reinforced concrete frames during destruction along inclined sections, the article offers a variant of a technical solution for cross-reinforcement of crossbars in such structures. The results of tests of monolithic reinforced concrete frames with a special impact in the form of a sudden hypothetical removal from the work of the extreme column are presented and experimental parameters of deformation, cracking and destruction of such structures in extreme conditions are given. The results obtained have shown the effectiveness of using the proposed variant of cross reinforcement of crossbars of monolithic frames to increase their survivability.

Thermal imaging surveys of residential premises in monolithic houses built in 2018 and 2019 of the cities of Russia are analyzed. Based on the regulatory requirements of the federal law “on energy saving”, the question arises about the existing shortcomings in the structural units of the monolithic overlap.

The traditional method of determining the isolation of air noise of a massive structure is considered, in accordance with SP 23-103-2003 “Design of sound insulation of enclosing structures of residential and public buildings”, in order to substantiate the composition and list of expert and design work to ensure sufficient sound insulation properties of enclosing structures. The relevance of the study is justified by the increase in noise comfort in residential buildings. Enclosing structures made of ceramic porous and aerated concrete blocks plastered with solutions, different in composition and density, were selected as the studied ones. Experimental design work has been carried out: the sound insulation index has been calculated, variable calculations have been performed, and variants of wall structures recommended for further experimental research have been substantiated. Analytical methods were applied, as well as the analysis of the results of theoretical research. The results obtained can be used in the design of residential apartment buildings.

Multifunctional canopies with a covering using a shape of shallow shells having a skylight for higher insolation are investigates. A derivation of equation is presented in view of the geometric nonlinearity of the thin-walled structure performance. A technique for solving systems of equations using the Bubnov-Galyorkin method is given. The concept of a universal shell canopy is proposed. Structures with various ways of fixing is simulated. The skylight is set on an arbitrary section of the structure with changing parameters. The influence of the shape and location of the skylight on the value of the critical load is investigated. The results of the investigations are given in a dimensionless form and are illustrated by graphs, which makes it convenient to use them in engineering calculations. Recommendations are given for correcting the shape and thickness of covering structures in the form of shallow shells with a skylight to maintain their bearing capacity.

The influence of operational factors on the thermal conductivity coefficient of polystyrene foam boards is investigated. In the study the initial density, humidity, the number of cycles of alternating freezing-thawing of polystyrene foam boards and the amplitude of the transition temperature through zero were taken as operational factors. To describe the response surface a four-factor laboratory experiment was conducted according to the second-order plan: 1 $$ Y = \left( {X_1 ,X_2 ,X_3 ,X_4 } \right) $$ At the same time a composite three-level symmetrical plan was used as it has a sufficiently high efficiency according to the main statistical criteria and includes 24 experiments. Based on the results of the laboratory experiment a regression model was constructed for further in-depth analysis which resulted in the conclusion about the influence of the investigated operational factors on thermal conductivity of polystyrene foam boards.

The purpose of the study is to evaluate the energy efficiency of the structure depending on the various options of the facade enclosing system. The variability of the facade system consists in considering several types of thermal insulation material. The following materials are selected for comparison: mineral wool, glass wool, and XPS insulation. The comparative analysis is based on the consideration of the total heat loss of the building, if the remaining parameters of the object remain unchanged, as well as on the basis of separate data on carbon emissions for each material under consideration. Based on the results obtained, conclusions are drawn about a more energy-efficient design with minimal impact on the environment.

Currently, we can observe an increasing trend toward the global warming of our planet. Multiple studies are aimed at assessing the impact of climate change on the construction industry and the infrastructure sector in general. At the same time, relatively few studies are dedicated to the climate change impact on the buildings’ need of energy for heating. The goal of this paper is to consider the change in the main parameters of the heating period in the Belgorod Region, which are required to calculate the heat protection of buildings. We have analyzed the duration of heating periods; the minimum temperatures during heating periods; the temperatures during the five coldest days in each heating period; the average temperatures during heating periods; and the number of heating degree days from 1936 to 2021. We have identified trends towards increasing minimum temperatures during heating periods; increasing temperatures of the five coldest days in each heating period; increasing average temperatures during heating periods, and a decreasing number of heating degree days. We have drawn a conclusion on the correlation between the global warming and the climate warming in the Belgorod Region. We have found that warming in the Belgorod Region occurs faster than it is estimated based on data in several studies in the early twenty-first century. We have given some recommendations for designing heating systems taking into account the trend towards increasing the number of heating degree days per heating period.

This paper analyzes basic structural constructions of fire protection systems and demonstrates reliability and evaluation methods of such constructions. Even in the best year, 9565 people got injured by fire, with the risk being 65 times more than acceptable. Today, the main approach is a so-called “risk-oriented approach”, aimed at minimizing the value of individual fire risk, or, maximizing the safety of people in residential and public buildings and structures. It would be more correct to consider this model as dynamic, as in need of constant improvement. Various methods and formulas were used to draw dependencies and assess risk of fire. The results show that the most significant system is Fire Alarm System (which is evident on the fact that this system is responsible for fire detection). The most usefulness is provided by Smoke Control System; however, it has the lowest reliability. Emergency Notification System, having the lowest usefulness, has a high reliability. Emergency Notification System reliability (effectiveness) can affect (control) the Fire Protection System effectiveness, but within certain limits. It was determined that one of the most important ways to minimize the risk is to use higher type Emergency Notification System. Paper also shows significance of the Fire Protection Systems in two aspects—reliability and structural reliability. System performance is fully disclosed in such parameter as—technical or functional efficiency, that depends on reliability and other parameters, for instance, human error, connectivity coefficient, topology efficiency etc.

Improvement of quality, decrease of terms and cost of construction are inseparably linked with problems of effective use of bulldozer equipment. The most important problem of control tractions modes of the bulldozer is the fullest use of traction opportunities of the machine at the expense of management of work tool. Automatic maintenance of the maximum traction power or resistance preset value on work tool is complicated by a large number of the random factors operating on the bulldozer. In this regard the system of automatic control has to possess possibility of self-adjustment. In this paper with applying of analytical simulation method and neural network technologies, been decomposed model bulldozers workflow as mechatronic system realized. Models of the sub-processes are included into the general structure of bulldozer’s workflow simulation model. They are intended to be used to study bulldozer’s separate units applying analytic dependences of between their workflow parameters and to simulate bulldozer’s workflow in general. Technique of identification and modeling of bulldozer’s workflow based on neural networking technologies is described.

The study of a local suction activated by perpendicular straight-flow jet from plasma cutting areas in the outlet space of the heterogeneous jet has been carried out. The results of the numerical simulation of various options for suction torch activation and experimental studies of the proposed suction apparatus design are presented. Axial velocity values at different air flow rates with the optimal flow rate ratio β are determined for the patented design of the local suction. It is revealed that the absence of negative factors of jets interaction during supply air jet formation in the form of radial air jet is achieved for the activating and removing jets ratio β = 0.8–1. It is also determined that schemes when the values of the flow ratios are β > 1 lead to an increase in the suction range, and the opening angle of the cutting radial air jet is close to 90°. Experimental data obtained by modelling the effects of suction and radially directed limiting flow has been obtained and substantiated. The geometrical parameters of the device at which an improvement in the conditions of the suction flow performance is observed have been obtained.

The issue of heat removal in various processes is topical and often determines the efficiency of the achieved result. The authors of the article consider the issue of heat removal in the process of manufacturing rectangular and cylindrical polymer products under specified process conditions. The authors propose an approach for determining the operating and design parameters of a cooling chamber based on the technique for determining the time dependence of the temperature of air-cooled workpieces in a turbulent flow regime. To estimate the time dependence of the temperature of the cooled rectangular workpieces, it is assumed that each of them is in approximately the same conditions. Therefore, to perform such an evaluation, the cooling of an individual product is considered. A similar approach is used for products in the form of thick-walled hollow cylinders. The complexity of formalization due to the random loading of workpieces into the container, is resolved by considering the so-called triangular packaging, closest to the natural laying of products. Thus, a method of engineering evaluation of air cooling of polymer products of various shapes required within the manufacturing process has been developed. The proposed approach makes it possible to evaluate the time dependence of the temperature of workpieces of various shapes and to select the optimal input parameters of the cooling method, i.e. it can be adapted to other materials of products.

The given paper poses some problems and possible ways of their solution concerning the applicability of heat accumulators in thermal power engineering. The need to install heat accumulators in the systems with different modes of heat supply and consumption is evident. It is suggested that the efficiency of such devices, in particular with respect to the physical data of the device, be increased through accumulation using the latent heat of the melting-solidification phase transition. By objective selection criteria, such as melting point, heat of phase transition, accessibility and non-toxicity, technical paraffin is of particular interest for the accumulation of thermal energy. In addition, the authors have justified the conditions for the implementation of ecological effectuality of heat accumulators application, including phase-shifting heat accumulators (FSHA), in traditional decentralized heat consumption systems, namely, reducing greenhouse gas emissions, primarily CO2. It has been established that if, with the growth in the heat load, and consequently the boiler capacity, the product of the square of CO2 volume concentration in the exhaust gases per their mass flow increases non-linearly, and this dependence is convex, switching off the heat source for the time of accumulated heat use gives a positive environmental effect, i.e., contributes to reduction in greenhouse gas emissions.

A person faces the problem of finding water sources when he due to certain circumstances finds himself in waterless, arid regions. Prolonged dehydration is detrimental to humans. It is well known that the loss of even one percent of the total amount of water in the body leads to painful disorders. In arid and desert regions, fresh water is found mainly in the atmosphere. Condensation (dew) appears at night. The problem is that people who find themselves in adverse conditions often do not have the skill to get water from it. The solution to this problem is the development of autonomous compact plants that provide the possibility of obtaining water under any conditions and in any natural situation. The article analyzes various methods for collecting water from the air and discusses the advantages and disadvantages of the proposed devices. The result of the work is the implementation of the author's device for obtaining water from atmospheric air, which differs from previously presented analogs with compactness and mobility.

As a result of experimental studies, a positive effect of a magnetic field on the properties of epoxy composites has been established. The article investigated the influence of an electromagnetic field created by using a constant electric current of various strengths passed through a rectangular metal plate, which was the base of the molds in the manufacture of samples from epoxy compositions. Epoxy compositions were made on the basis of epoxy-diane resin. The composites were cured with polyethylene polyamine. Pyrite cinders served as a filler in the filled compositions. In the course of the study, the following were experimentally determined: compressive strength, tensile strength in bending, dynamic modulus of elasticity, fracture energy and microhardness. The results obtained show an improvement in the physical and mechanical properties of polymer composites processed using a magnetic field.