Introduction. Currently, much attention is paid to the development of the Arctic zone of the Russian Federation. The increased interest in the Russian Arctic is associated not only with the discovery of the Northern Sea Route, but also with the great economic, social, raw materials and tourism potential of the territory. The development of the Arctic city is impossible without taking into account its public spaces, their condition and their connectivity. It is the inseparability of cultural, historical and natural objects of the city that makes it possible to create a sustainable, capable of development cultural and social framework.

Materials and methods. The analysis of cultural, historical and natural objects of the Arctic cities was carried out, modern GIS technologies for modelling of the cultural and social framework were used, as approbation of theoretical research, an experiment was conducted on the example of the Salekhard city.

Results. The developed methodology makes it possible to determine the cultural and social framework (CSF) of the Arctic city and develop a proposal for improvement. The creation of the cultural and social framework of the Arctic city will help to develop a network of public spaces and provide a link between them, which is extremely important in the complex climatic conditions of the North. The design experiment on the example of the city of Salekhard confirmed the applicability of the methodology.

Conclusions. The study showed that the current state of cultural, historical and natural objects of the Arctic cities requires the attention of city planners. It is also obvious that the connectivity of attraction objects in the complex climate of the Arctic cities is a necessary condition for security. The methodology of building a cultural and public framework in the Arctic cities will allow to form a coherent network of public spaces in the city, increase the comfort and safety of the living environment for residents, as well as help to develop tourist routes in the city.

Introduction. Successful economic and social development of urban territories requires a sustainable transport system that provides reliable connections between territories and a high level of their transport accessibility for the daily social and economic activities of the population. The most important elements of the transport and planning framework of the agglomeration are linear objects, represented by transport corridors, which determine the bulk of transport costs for population movements, and hence transport accessibility of territories. A high level of transport service in such important elements as transport corridors directly affects the formation of sustainable daily migrations of the population and the development potential of the adjacent territories, and therefore affects the formation of the agglomeration boundaries.

Materials and methods. For the territory of Irkutsk agglomeration, which includes Irkutsk city as the main core of agglomeration, satellite cities Angarsk and Shelekhov and the surrounding territory of Irkutsk district, approaches to the formation of a unified transport model of agglomeration as the main tool for assessing transport demand, analyzing the distribution of traffic flows and indicators of the effectiveness of measures to develop the territories of transport corridors and the territories served by them are proposed. The paper considers special cases of the constituent parts of the models for assessing transport demand for movements between individual municipalities. An approach to estimating transport demand on adjacent conjugate transport corridors, previously used only for individual corridors is proposed.

Results. The significance indicators of transport corridors, including the volume of transport work in relation to their total length were obtained. The example of the application of transport model of Irkutsk agglomeration to solve the problems of the formation of new transport corridors is presented.

Conclusions. It is concluded that the proposed approaches to the formation of the transport model allow to prepare the necessary tools in conditions of limited opportunities for mass surveys, as well as maximize the use of existing transport models developed earlier for individual municipalities and transport corridors, combining them into a single transport model.

Introduction. The research is aimed at the development of methods for assessing and analyzing the structural reliability of elements of building structures in practical tasks when statistical data about random variables may be incomplete or limited. In such cases, it is difficult to identify the specific type of the exact cumulative distribution function of a random variable or to give an accurate estimate of the distribution parameter, because there is a need to take into account epistemic uncertainty in addition to aleatory uncertainty.

Materials and methods. For effective modelling of two types of uncertainties, it is proposed to use boundary distribution functions of a random variable that form a p-box (probability box). P-boxes take into account both types of uncertainty: caused by natural variability of random parameters and uncertainty caused by lack of knowledge about the random variable (number of control samples, accuracy of measuring instruments, etc.).

Results. The paper proposes a new type of p-box based on the Dvoretzky – Kiefer – Wolfowitz inequality and Chebyshev’s inequality, which form two boundary distribution functions based on the sample population data. The numerical example shows the approach to arithmetic operations with p-boxes, which make it possible to bring complex mathematical models to simpler ones and estimate the failure probability in an interval form. The difference between the analytical and numerical solution for the example is 0.9 %.

Conclusions. Boundary distribution functions form a more cautious and reliable approach to the structural reliability analysis. The result of reliability assessment using p-boxes is presented in an interval form. If the interval turns out to be too wide and uninformative, then it is necessary to increase the quantity or quality of statistical data or to increase the cross-sections of structural elements to achieve the lower limit of the interval of the required reliability level.

Introduction. The implementation of modular buildings leads to the necessity to develop methods of their calculation, including dynamic loads too. One of the main parameters in the calculation of loads from dynamic effects is the determination of natural frequencies of vibrations of the structure. The subject of research is the natural vibrational frequency of modular buildings. The aim of the research is to determine the effect of the compliance of intramodular joints on the vibrational frequencies of modular buildings.

Materials and methods. The paper deals with the determination of the first natural frequency of vibration of a modular building with semi-rigid intramodular joints, and the influence of the compliance of the joints on the frequency. The author of the paper proposed and substantiated an analytical formula for determining the natural vibration frequencies, taking into account the stiffness parameters of modular buildings and the rigidity of intramodular joints. The proposed formula has sufficient accuracy for engineering calculations. At the same time, it allows to analyze the natural vibrational frequencies of modular buildings with different parameters without constructing calculation schemes in computer systems, which significantly speeds up the search for rational design solutions.

Results. According to the obtained results, the discrepancy in the frequency values calculated by the finite element method and analytically for a one-story building with different ratios of the rotational stiffness of the joints does not exceed 1.5 %. For a multi-storey modular building, the difference in determining the natural vibration frequencies increases with the number of storeys, but does not exceed 10 % for three storeys.

Conclusions. Based on the example of a modular building, it is shown that it is necessary to take into account the joint rigidity to determine the correct value of natural vibrational frequencies. Ignoring of the rotational stiffness of the joints can lead to an error in determining the dynamic effects.

Introduction. With the time of operation of buildings and structures, soil compaction occurs under the base of their foundations from all the acting loads from the building. The purpose of the research is to study the movements of
the building foundations during the construction of the underground part with their possible preventive reinforcement during reconstruction, taking into account changes in the strength and deformation characteristics of soils. The solution of this problem will allow the most detailed consideration of buildings settlement during reconstruction.

Materials and methods. A series of numerical calculations in the PLAXIS 2D software package of the interaction of the foundation with the foundation soil during the reconstruction of a building with the development of underground space, including the construction of two or three underground floors, were carried out.

Results. The effect of taking into account the improved soil characteristics with regard to the time of building operation on the settlement of existing foundations during reconstruction with the development of underground space is studied. It was revealed that the reinforcement of foundations with soil-cement elements reduces the settlement during reconstruction approximately in two times. The influence of the number of floors of the designed underground car park on the stress-strain state of the soil massif is considered.

Conclusions. Numerical studies show that strengthening of soils under the base of existing foundations leads to a decrease in the building settlement during reconstruction with the development of underground space. Reinforcement of the existing foundation with soil-cement elements makes it possible not to exceed the maximum additional settlement of the reconstructed building. A decrease in the settlement of existing foundations with a decrease in the number of storeys of the designed underground part is revealed.

Introduction. The most common method of determining the mechanical characteristics of the soil is triaxial compression testing. This type of testing is widely used both for applied and scientific purposes, and is described in the works of both domestic and foreign authors, as well as in regulatory and technical documentation. However, within the framework of scientific works by various authors, the coefficient of uneven expansion of a soil sample during triaxial tests is often neglected and is not taken into account when processing the test results. In the existing current regulatory and technical documents, such as GOST 12248.3–2020, consideration of the coefficient of uneven expansion of the soil sample under triaxial compression b is of a recommendatory nature.

Materials and methods. Within the framework of the work, experimental studies by the triaxial compression method were carried out on sandy soil samples of different granulometric composition in order to determine its mechanical characteristics using two different methods of processing laboratory test results — taking into account the coefficient of uneven expansion of the soil sample and without it.

Results. According to the results of the performed experimental studies, it was found that the exclusion of the expansion non-linearity coefficient b from the processing of laboratory test results leads to a significant overestimation of the values of the internal friction angle. However, the values of secant modulus of deformation at 50 % strength E50 are lower by an average of 7.7 % when the nonlinear expansion coefficient of the steel is excluded from the processing.

Conclusions. Analyzing the results obtained, as well as taking into account various factors influencing the results of the study (density, humidity, etc.), additional laboratory tests are required in order to further clarify the correlation dependencies in determining the strength and deformation characteristics of sandy soils, with and without taking into account the coefficient b.

Introduction. A distinctive feature of CLT panels is the cross arrangement of planks (lamellae) in different layers of the board. Due to the anisotropy of wood, this design allows for high strength and stiffness in different directions of stress action, which has made this material one of the most promising to be studied in recent decades. This article examines the influence of the thickness of transverse and longitudinal layers in five-layer slabs of cross-glued timber boards, or CLT panels, on the deformation and distribution of the resulting normal and tangential stresses. The relevance of the work is conditioned by the necessity of obtaining calculated data to analyze changes in the strength characteristics of boards with different variations in the thickness of longitudinal and transverse layers in order to choose the most effective configuration of the board.

Materials and methods. The studies were carried out by numerical methods using SCAD+ PC using FEM (Finite element method). At the same time, the three-dimensional finite elements are parallelepipeds. The design scheme is defined as a general-type system, whose deformations and its main unknowns are represented by linear displacements of nodal points along the X, Y, Z axes and rotations around these axes. As a design structure, a five-layer slab with cross-directed layers was chosen in such a way that the outer (1, 5) and central inner (3) layers are longitudinal, and the remaining inner (2, 4) are transverse. The simplified design scheme is a pivotally supported beam.

Results. The results of the study and calculations made using SCAD+ were applied to make tables and graphs showing dependence of deflection, distribution of normal and tangential stresses on the thickness of transverse and longitudinal layers of the board.

Conclusions. The obtained data allow us to evaluate the influence of thickness on deformability and stress distribution in five-layer CLT panels. The significance of the conducted research is in the expansion of scientific and technical knowledge base in the field of wooden structures.

Introduction. The purpose of the research is to study the regularities of development of hazardous geological processes caused by the termination of construction of buildings for a long time. These processes include any changes in the Earth’s crust that can have a negative impact on the living conditions of the population and cause economic damage.

Materials and methods. The research was carried out on the territory of Moscow, as well as Moscow and Kaluga regions. The subject of the study was the natural and technical system formed in the process of destruction of incomplete construction objects. Special attention was paid to the territories surrounding the long-term abandoned buildings, where no work had been carried out for many years.

Results. On the territories surrounding the abandoned incomplete objects, the greatest danger are: suffosion, karst, erosion, landslides, liquefaction of soils and rocks, causing a decrease in their strength. The generalized analysis of the obtained data made it possible to create a classification of incomplete construction objects. It simultaneously takes into account the condition of building structures and hazardous changes in the surrounding area. The practical application of the classification will provide a systemic character of activities aimed at solving the problem of abandoned buildings. Assigning a certain status to an unfinished construction object can serve as a justification for its restoration or liquidation. A programme for depreservation of incomplete objects was developed.

Conclusions. An adequate idea of the impact of an unfinished construction project on living conditions in the city can only be given by studying the natural and technical system that formed during the period of stoppage of work. Its main elements are: an incomplete building and a site where the development of hazardous processes caused by destruction is observed. It is necessary to create an information array on incomplete construction objects, which would include long-term abandoned buildings that are not subject to restoration. The depreservation of incomplete buildings for their further construction should be carried out after a mandatory study of tendencies in the development of dangerous geological processes that occurred during the period of construction stoppage.

Introduction. Electric boilers are considered as an important element of the energy transition from the use of hydrocarbon fuels to renewable energy. Electric boiler is one of the popular solutions of “Power-to-Heat” technology, widely used in households for heating with water systems with radiators and low-temperature heating devices of the “floor heating” type. The paper considers a variant of Joule heating of the coolant of heating systems, by means of which heat is released when an electric current passes through a conductive element.

Materials and methods. The object of the research is the variants of designs of heat exchangers for generating heat energy using resistor heating elements of normal conductor and semiconductor type. Various variants of indirect heating of the coolant and contacts of the surface of the heating elements with the coolant are considered. Methods of comparative analysis and scoring of the applicability of various designs are used in the work.

Results. The classification of electric boilers by types of heating resistors, by contact, by placement of heating elements in the heat exchanger, by the shape of the heat exchanger, by the variant heating element contact with the coolant is presented. A comparative comprehensive analysis of variants of electric heat generators is given.

Conclusions. The results of comparative analysis of design variants of electric boilers show the prospectively of using semiconductor thermistors as heating elements. According to the design of the heat energy generation chamber in terms of compactness, power density and reduction of precipitation conditions for coolant stiffness, channel plate electric heat exchangers are the most effective.

Introduction. Currently, there is a wide variety of methods for monitoring the condition of pipeline systems which require a different set of equipment. However, these methods are not applied for internal water supply systems due to restrictions on pipe diameters and complicated availability of communications

Materials and methods. To assess the corrosion activity of water and determine the possibility of calcium carbonate release, various indices can be used: Langelier, Risner, Snow-Jackson, etc. When monitoring water supply systems with signs of corrosion using an electron microscope, it was found that the composition of the corrosive sediment contains a large amount of zinc, and, in some cases, copper. The essence of the proposed method is that a preliminary prepared steel indicator sample cut from an uncoated pipe was placed in a container under a stream of cold or hot water in the investigated water supply system made of galvanized steel pipes (including copper-containing fittings and heat exchangers), the sample was kept under the stream for 3–4 hours until the formation of surfaces of firmly attached corrosion products (sediment).

Results. Fistulas were found on horizontal sections, on turns, in places where pipelines are welded. When laying pipes in parallel in a horizontal plane, it is necessary to bypass the pipes located next to the risers, which leads to the appearance of U-shaped or U-shaped contours of horizontally laid pipes. The most obvious reason for abnormally rapid corrosion in horizontally arranged pipelines with a U-shaped connection scheme of risers is the low speed of water movement. At low velocity of water flow in pipes with a change in the direction of water movement from horizontal to vertical and down, air will accumulate on the horizontal section of the main pipeline, while sediment will accumulate on the horizontal section going to the riser.

Conclusions. The experience of the survey of water supply systems of buildings shows that, first of all, it is necessary to assess the impact of water quality on corrosion of pipelines according to stability indices, which in some cases can provide an answer to the possibility of abnormally rapid corrosion.

Introduction. The current economic conditions in the Russian Federation have significantly changed the priorities of state policy in the field of industrial development, which is expressed in the provision of an effective policy of spatial planning and creation of industrial facilities in regions where there are favourable conditions for this. One of the directions of
the implementation of these policy priorities is the use of special economic zones (SEZ) with technological infrastructure for the implementation projects for the construction of industrial facilities on their territories. In this regard, it is relevant to develop a set of methods that contribute implementation of state policy in the field of industry, which will provide an objective assessment of prospects for the implementation of industrial construction projects in the SEZ, considering their advantages for the participants of the investment and construction process.

Materials and methods. The initial materials of the study were the data of official statistics of the Russian Federation, characterizing investment processes in the industrial sector of the country. The methodological basis of the work was
the provisions of theories of infographic modelling, functional systems, and statistical research methods — regression and correlation analysis, which are aimed at establishing the significance of indicators affecting the effectiveness of management and prospects for implementation of industrial construction projects in the SEZ.

Results. As a result of the research, a set of indicators characterizing the prospects for implementation of industrial construction projects in the SEZ based on a comprehensive analysis of the project environment that surrounds it was formed. Analytical dependencies of the performance indicators of investment and construction organizations carrying out the construction of industrial facilities were established and formalized, allowing to determine the closeness of connection of these indicators and under conditions of variability of their values, which formed the basis of the developed set of evaluation methods.

Conclusions. The developed approach to assessing the prospects for implementation of industrial construction projects in the SEZ allows expanding the information base for making managerial decisions when choosing locations for new industrial facilities, based on the specification of the conditions for implementation of project activities by its participants, established in the regions of the country. Improving of the state statistics data system in the proposed directions can expand the representativeness and range of analytics for decision-making.

Introduction. In modern conditions, the fundamental basis of construction is the process of creating value of the capital construction object for the consumer. The article examines the process of creation of capital construction projects as a value chain and substantiates the influence of digital transformation on the development and dynamics of this chain. The analysis of modern research on the impact of digitalization on value chains is carried out, the results of the analysis are projected onto the processes of digital transformation of the construction ecosystem. The main existing problems of project implementation efficiency in construction, including from the position of the actual task of increasing labour productivity, as well as the prospects for digitalization of construction from the position of value chains using the tools of the lean manufacturing concept are identified. A mechanism for implementing the concept of lean manufacturing in construction using digitalization tools is proposed. Based on the results of the financial and economic analysis, the effects of the implementation of the proposed measures that affect the timing of the implementation of the IСP, cost and quality parameters are calculated. The proposed approach contributes to the creation of a database on the occurrence and ways to solve problems in business processes, as well as creates opportunities for continuous training and motivation of employees, which is fully consistent with the need for continuous improvement in lean construction.

Materials and methods. The methodological basis of the study is the concept of lean construction in relation to aspects of the transformation of the digital construction ecosystem. In addition, systematic and situational approaches, methods of qualitative, comparative and factor analysis of the results of foreign and domestic experience were used in the study.
The tools of investment analysis and financial and economic modelling were used to analyze the results of the implementation of lean construction tools within the framework of investment and construction projects.

Results. The authors propose a practical approach to the implementation of the concept of lean production using digitalization tools in the activities of a construction company. The analysis of the results of the introduction of digital tools based on the concept of lean construction in Russia made it possible to quantify the losses in the framework of the implementation of investment and construction projects, as well as to calculate the effects of the implementation of the proposed solutions.

Conclusions. The study recommends participants of the construction ecosystem to implement the concept of lean construction in integration with digital technologies in accordance with the proposed practical approach to increase labour productivity and the efficiency of investment projects implemented.