Introduction. The contradictions between the intensification of anthropogenic activities and the need to preserve and strengthen natural complexes are becoming more acute. The rapid growth of the urban population, the global problem of climate change worldwide, and the high level of anthropogenic impact on natural landscapes require modern cities to implement strategies for sustainable development of territories in general and improve techniques to strengthen the natural and ecological framework in particular. The purpose of the study is to identify regional features and problems of the formation of the ecological framework of Belgorod and to develop recommendations for ensuring a sustainable highly urbanized environment of a large city.

Materials and methods. A comprehensive approach, an analytical review of territorial planning documents and urban planning zoning, a problem analysis of the current state of the ecological framework of Belgorod, a SWOT analysis of the natural resource potential of the territory and an analogue modelling were applied.

Results. Regional peculiarities and problems of formation of the ecological framework of Belgorod are revealed. A SWOT analysis of the natural resource potential of the territory was carried out. Weaknesses and strengths, opportunities and threats were identified. The basic principles of the formation of the ecological framework of Belgorod are proposed: the principle of continuity of green areas, the principle of decentralization of green zones, the principle of optimality of anthropogenic load, the principle of water-saving design; the principle of integration of gully-girder complexes into the natural and ecological framework; the principle of regeneration of landscapes of riverine territories; the principle of reclamation of spent quarries and their integration into the ecological framework.

Conclusions. The necessity of supplementing the materials “on the substantiation of the master plan for the development of the urban circle Belgorod until 2025” in terms of the development of an environmental framework scheme is justified. A conceptual spatial model if developed to strengthen the ecological framework of Belgorod. A number of recommendations are proposed to ensure comprehensive work to strengthen the ecological framework of the city.

Introduction. The issue of the formation of a “heat island”, characterized by active thermal and aerodynamic characteristics in the air zone of the urban surface layer of the atmosphere of the “heat island” is considered. The study of the thermal regime of the city, based on local climatic and environmental data, is the most urgent task in the formation and transformation of the “urban heat island”. The conditions of a comfortable human stay in cities located in southern latitudes are inextricably linked with radiation exposure under the influence of solar radiation, which are aggravated by the influence of the “heat island”. Compilation of a model of transformational changes in the air dome of the “heat island”, as well as the dependence of transformation on various types of morphotypes of the active surface of urban infrastructure is the main objective of this study.

Methods and materials. Based on the generalization of a number of results of meteorological, climatic, microclimatic and thermophysical studies, a software package was developed to study the process of formation and transformation of the “heat island”. The data was used in the form of satellite images from the Landsat-8 spacecraft with a TIRS sensor.

Results. The analysis of the results of theoretical studies and calculations of the formation and transformation of the thermal envelope of an urban area using computer modelling showed the dependence of the qualitative and quantitative thermodynamic and aerodynamic characteristics of the “heat island” and the turbulence coefficient. It is established that the turbulence coefficient directly affects the transformation of the dome of the “heat island” in the direction of movement of the main wind flow. At the same time, the higher the coefficient, the more dynamic the transformation of the dome along the length X and height Z.

Conclusions. The developed methodology of qualitative and quantitative assessment of the heat and wind regime of the urban “heat island” model and its transformation allows preliminary forecasting and assessment of the temperature field of the thermal air envelope of the urban environment. A model of transformational changes in the air dome of the “heat island” with various morphotypes of the active surface of the urban infrastructure is compiled.

Introduction. The relevance of the research is determined by the features of the design and organizational-and-technological solutions formed in the process of developing modern construction projects, consisting in the use of a limited composition of technological resources (building materials, machines and equipment), which determines the discreteness of the values of the characteristics of the above-mentioned solutions. The purpose of the study is to develop tools to justify the combination of standard values of the characteristics of materials used for the device of layers of the enclosing structure, using quadratic optimization tools.

Materials and methods. Mathematical models for optimization of the thickness for the materials used as layers of the enclosing structure in a residential building are developed, based on discrete and binary unknown variables, as well as on the criteria of the weighted average (by the thickness of layers) temperature, total thickness and thermal resistance of the structure. The mathematical models have a quadratic structure of the objective function and a linear structure of indirect constraints, but the presence of constraints related to the discreteness (binarity) of unknown variables significantly complicates the process of the models’ implementation due to the lack of suitable standard (available in modern software environments for mathematical modelling) computational algorithms. In this regard, it was decided to develop a user computational algorithm that includes the advantages of the branch and bound method used to determine the optimal values of unknown variables for which discreteness or binary requirements are specified, as well as the interior point method used to determine the optimal solution of the quadratic optimization model without taking into account the above requirements.

Results. To practically verify the developed mathematical models, the proposed computational algorithm was applied to justify the selection of standard material characteristics for the given enclosure structure. The resulting data enabled the establishment of dependencies between the thermal performance indicators of the structure and the required thickness of its layers.

Conclusions. Based on the analysis of the results obtained from using the developed mathematical models and computational algorithm, the significant practical value of the proposed tools was confirmed.

Introduction. The behaviour of folded elements made of textile-reinforced concrete under loading is investigated. Textile-reinforced concrete is a relatively new building material that is attracting increasing interest from researchers. Because the elements of textile-reinforced concrete are thin in cross section, they cannot cover large-span buildings. However, textile-reinforced concrete is well suited for the production of folded shells, as in the case of ferrocement. The aim of this study is to investigate the strength of textile-reinforced concrete folds under loading.

Materials and methods. Textile-reinforced concrete folded specimens were manufactured. Warp-knitted meshes made of alkali-resistant glass fibres (AR) and carbon fibres (C) were used to reinforce the elements. The specimens were tested. Based on the test results, a comparison of the fold properties was performed depending on their shape (triangular or trapezoidal) and type of reinforcement.

Results. The average failure load for the triangular folds was 5.9 kN for nonreinforced specimens, 4.8 kN for specimens reinforced with AR rovings, and 3.6 kN for specimens reinforced with C rovings. For the trapezoidal folds, the average failure load was 8.0 kN for nonreinforced specimens, 8.7 kN for AR reinforcement, and 10.7 kN for C reinforcement. The average compressive strength of fine-grain concrete was 25.08 MPa. The flexural strength of the fold elements was 7.29 MPa for nonreinforced specimens, 9.33 MPa for AR-reinforced specimens, and 15.4 MPa for C-reinforced specimens.

Conclusions. The currently existing regulatory framework is insufficient for wide application of textile-reinforced concrete products in construction. To date, there are scattered experimental and theoretical studies on the mechanical properties of the material and the behaviour of structures made of textile-reinforced concrete under loading. Experimental data on the behaviour of folded elements made of textile-reinforced concrete under loading are presented.

Introduction. Currently, in engineering practice, a model of a die lying on an elastic homogeneous base is used to evaluate the joint dynamic operation of buildings with a soil base. The presence of layers with sharply different stiffness, as well as the order of their location in the soil column, leads to significant changes in the spectrum of resonant frequencies and the magnitude of the dynamic response. Therefore, it is important to take into account the inhomogeneity and layered structure of the soil foundation for a correct assessment of resonance processes arising from joint vibrations of the structure and the foundation. The purpose of the study is to analyze the reaction of the “structure – multilayer base” system depending on the ratios of their stiffness, as well as to compare the results obtained by modelling a multilayer and equivalent homogeneous base.

Materials and methods. A computational model of a horizontal layered medium is used. The structure as an element of a layered system with reduced stiffness characteristics. The seismic load in the form of a vertical propagating shear wave is modeled by a stationary random process. The amplitude-frequency characteristics of the system as a whole, as well as for each individual layer, spectral output densities and dynamic coefficients are used for analysis.

Results. It was found that with a decrease in the rigidity of the building, its contribution to the overall amplitude-frequency response of the system increases. A numerical assessment of the change in the dynamism coefficient with changes in the system parameters has been performed. A comparison was made of the response of a structure on a multilayer base with a response on a single base with equivalent characteristics.

Conclusions. The simplified representation of the soil as homogeneous, without taking into account its layered structure, reduces the value of the dynamism coefficient to 30 %. The resonant frequencies of the “building – hard layer – weak layer” system are mainly determined by the resonant frequencies of the weak lower layer, especially with an increase in the rigidity of buildings. A similar pattern is characteristic for a homogeneous base. In the “building – weak layer – hard layer” system, the resonant frequencies depend on the frequencies of the base layers, as well as on the natural frequencies of the building.

Introduction. Existing normative methodologies do not always adequately describe the dynamic response of high-rise buildings under wind action, especially when considering complex geometry and interaction with surrounding developments. In this study, a numerical simulation methodology for the dynamic response of high-rise buildings under wind action is developed, accounting for aerodynamic interference and resolving the spectrum of turbulent fluctuations based on unsteady CFD-modelling and direct dynamic finite element analysis. An example of using this methodology is shown, along with numerical results of modelling the dynamic response at different wind attack angles of the “Evolution” Tower, which is part of the Moscow International Business Centre “Moscow-City”.

Materials and methods. The methodology divides the problem into two stages: unsteady aerodynamic modelling and calculation of the dynamic response of the structure. Aerodynamic models of the building complex of the Moscow International Business Centre “Moscow-City” and a finite element model of the “Evolution” Tower were developed for this purpose. A hybrid turbulence model SBES was applied for aerodynamic simulation, allowing the resolving of the spectrum of turbulent fluctuations. The dynamic response of the building is calculated using direct dynamic finite element analysis based on the implicit Newmark method.

Results. The results of aerodynamic simulation are presented as floor-by-floor distributions of aerodynamic forces and moments for different wind directions. The calculated dynamic response based on these results showed a significant influence of aerodynamic interference on the building’s behaviour. Comparison with calculations using the normative methodology CP 20.13330.2016 demonstrated the conservatism of the latter and the need for more accurate calculation methods.

Conclusions. The proposed methodology allows for a more accurate prediction of the dynamic response of high-rise buildings under wind action, which is crucial for ensuring mechanical safety and dynamic comfort. It is recommended to implement this methodology in the practice of design justification for high-rise buildings, which will optimize structural solutions, enhance mechanical safety, and increase the economic efficiency of high-rise construction.

Introduction. Cellular concrete is one of the most common building materials. Increase of its efficiency can be ensured by carrying out a complex modification. The paper proposes a formulation and technological solution for the production of non-autoclaved foam concrete, which consists in the use of a complex of modifying additives, including mineral dispersed and micro-reinforcing components. Their introduction contributes to stabilization of the foam concrete mixture, regulation of the processes of structure formation and control the performance of the finished material.

Materials and methods. Portland cement of CEM I 42.5N grade, protein foaming agent “Etalon” were used. Modification of foam concrete was carried out by: quartz suspension obtained by wet milling of quartz sand, synthesized anhydrite, hardening activator Na2SO4, basalt and glass fibres. The main physical and mechanical characteristics of foam concrete were determined according to the current regulatory and technical documents. The microstructure was studied using scanning electron microscopy.

Results. The influence of formulation factors on the operational quality indicators of non-autoclaved foam concrete for thermal insulation purposes was established, multicriteria optimization was carried out, rational compositions were determined. Materials with a density grade of D500 and a strength class of B1.5–B2 were obtained.

Conclusions. The replacement of a part of the Portland cement binder with a dispersed modifier in combination with micro-reinforcing fibres makes it possible to obtain materials with improved properties at reduced production costs, namely, by optimizing the cellular structure, strength indicators increase while maintaining density and thermal conductivity values. This formulation solution leads to the compaction and strengthening of the interpore partitions, as a result, the “monolithization” of the matrix and the frame structure of the composite created by micro-reinforcing components. The material is characterized by polydisperse porosity with a wide range of pore sizes with a shape transitioning from regular rounded to polyhedral. As a result, the physico-mechanical and thermal insulation properties of non-autoclaved foam concrete are increased.

Introduction. Thermal corrosion of cement stone is a serious issue in public utilities and other structures operated under conditions of elevated temperature and humidity. This type of corrosion is thoroughly studied by experts in plug-back work, but it is less researched in construction materials science. Due to the fact that technologies of plugging and construction works have significant differences, further research in this field is necessary.

Materials and methods. The study used fly ash from the Smolensk Hydroelectric Power Station and granulated blast furnace slag from the Novolipetsk Steel Plant in dosage of 30 %. Portland cement CEM I 42.5 N from CJSC “Oskolcement” (GOST 31108–2020) was used as the binder. The compressive and flexural strength of the specimens was determined
using a PGM-100MG4 hydraulic press. Hydration products were analyzed using an ARL 9900 Work Station X-ray fluorescence spectrometer, an STA 449 F1 Jupiter NETZSCH synchro nous thermal analyzer, and the microstructure of the cement stone was examined using a Tescan Mira 3 scanning electron microscope.

Results. It was found that active mineral additives of fly ash and slag increase the thermal stability coefficient of the cement stone from 0.47 to 0.69 (slag) and 0.72 (fly ash) after 12 months of testing. Significant differences between hydration products under normal and thermal-humidy conditions were revealed through the combined use of X-ray phase and derivatographic analysis with electron microscopy studies. The stone structure under prolonged curing in thermal-humidy conditions is complex and heterogeneous, with well-crystallized calcium hydrosilicates of varying basicity forming alongside tobermorite gel.

Conclusions. The addition of active mineral additives, such as fly ash and granulated blast furnace slag, contributes to the increased thermal stability of cement stone. Under elevated temperature and humidity, the formation of low-basicity hydrosilicates is intensified, which mitigates the difference between the solubility of the contact zones and isolated particles, thereby enhancing the thermal stability of the system.

Introduction. Lifting mechanisms are important in modern construction production, providing an efficient and safe way to move and lift materials and building structures. Stations, travel routes, and service areas for lifting mechanisms are reflected in construction master plans. Site design begins with the installation of lifting equipment. In common practice, when comparing crane options, technical and economic indicators associated with the purchase, rental and operation of the mechanism are taken into account, without taking into account how a particular mechanization option affects the location of construction infrastructure and technical and economic indicators of the construction plan. Due to the increasing space constraint, it is necessary to revise the system of technical and economic parameters for construction plans assessing.

Materials and methods. The normative-legal base regulating the construction site organization, lifting mechanisms placement and safe construction production is studied. Design and working documentation is analyzed: construction organization projects, projects of works production, projects of works production with application of lifting facilities. The variant technological design of construction plans was carried out and the influence of the accepted lifting mechanism on the compactness of the construction site at erection of low-rise objects was estimated.

Results. The obtained results expand the idea about the choice of lifting mechanisms for the erection of low-rise objects. It is suggested to supplement the system of technical and economic indicators of evaluation of the efficiency of the adopted technological solutions with the presented evaluation indicators, which take into account the location of hoisting cranes on the construction site and affect the compactness of the construction site.

Conclusions. The design of construction master plans should be varied and performed with the use of various lifting equipment. The effectiveness of choosing lifting machinery should be determined by a system of parameters along with the main technical and economic parameters to assess construction plans.

Introduction. According to the strategic priorities of the Russian Federation in the field of energy, energy saving and rational use of resources is the focus of attention in the development and functioning of the fuel and energy complex of the country. However, the energy resources of Russia are used with insufficient efficiency, and high energy intensity values of the country’s gross domestic product indicate a strong deterioration of fixed assets and their technological backwardness. The domestic heat supply sector, which is an important part of the country’s fuel and energy complex, shows low efficiency and reliability, as evidenced by an increase in the number of accidents, high heat losses in networks and a significant proportion of infrastructure in need of replacement. One of the tools contributing to the implementation of resource and energy saving processes in the field of heat supply is the use of innovations that allow accelerating the pace of development of the sphere in the strategic perspective. In this regard, the purpose of the study is to form a conceptual approach of the management of the innovative development of the heat supply sector.

Materials and methods. The normative basis of the study is the legislative acts of the Russian Federation regulating the activities of heat supply and determining the directions of state energy policy. The work is based on the fundamental theories of management and the theory of innovation. The methodological basis of the study is the approaches developed in the economic literature to determining the innovation climate and innovative potential of organizations, approaches to assessing the effectiveness of the introduction and implementation of innovations, as well as the provisions of systemic, project and stakeholder approaches to management.

Results. The result of the research is the formed conceptual approach to the management of innovative development of the heat supply sector, specifying the conditions that promote innovative development, and determining the possibility of developing methods to ensure these conditions to achieve the goals of innovative development of heat supply.

Conclusions. The proposed management tool for the innovative development of the heat supply sector makes it possible to implement strategic prospects for its development in the focus of resource and energy conservation based on the use of innovative materials, technologies and control systems.