Introduction. Linear urban planning systems have a specific spatial organization that imposes special requirements for the formation of a water-green framework (WGF). The WGF is a key element in ensuring their ecological sustainability, improving the microclimate, and enhancing the quality of the environment. The relevance of the study is due to the need to develop a methodology that allows not only to describe but also to quantitatively assess and predict the sustainability of the WGF structure. The scientific novelty of the work lies in the development of a three-stage methodology integrating theoretical modelling, mathematical formalization, and sustainability assessment, as well as in the testing of this methodology on the example of Volgograd with the calculation of an integral sustainability indicator.

Materials and methods. The research is based on a synthesis of systemic, comprehensive, and program-targeted approaches. The methodology includes three stages: analytical (spatial zoning, identification of WGF elements, comprehensive assessment using GIS analysis); conceptual modelling (development of an idealized WGF model)); mathematical modelling and assessment. The principal component method was used to assess the sustainability of nodes, and the analytic hierarchy process was used to determine the weight coefficients in the integral model.

Results. A theoretical model of the water-green framework structure for a linear urban planning system is proposed. A comprehensive methodology for the formation and assessment of the WGF model was developed and tested on the example of Volgograd. An integral sustainability indicator, UWGF, aggregating the normalized indices of longitudinal belts (Jb), transverse corridors (Jc), and nodes (Jn), is proposed. The weight coefficients of the contribution of each structural element of the WGF to its sustainability are determined.

Conclusions. The practical significance of the work lies in the proposal of a toolkit for the quantitative assessment and strategic planning of the development of the WGF for linear urban planning systems. The proposed methodology allows not only to state problems but also to identify their structural causes, determining the priority of impact on the system-forming (longitudinal belts) and connecting (transverse corridors) elements. The research results can be applied in urban planning and territorial planning for linear urban planning systems, in particular, in the regions of the Volga region, the Urals, and Siberia.

Introduction. At the moment, the use of fibre-reinforced polymer (FRP) reinforcement in load-bearing structures of buildings is mainly reduced to foundations. This is due to the physical and mechanical properties of fibre-reinforced polymer. To expand the field of application of composite reinforcement, it is proposed to use it as an upper reinforcement of slabs of monolithic concrete frames. The frame is designed to be resistant to progressive collapse.

Materials and methods. The object of the numerical study is a 10-storey building with a frame-wall structural system. For comparison, two options for reinforcing floor slabs were considered — bar mat in the lower and upper zones: 1 — lower and upper reinforcement from reinforcing bars of class A500 of National State Standard 34028–2016; 2 — lower reinforcement made of reinforcing bars of class A500, upper reinforcement made of glass fibre-reinforced polymer (GFRP) of National State Standard 31938–2022. Calculations were performed for the main combination of loads and for resistance to progressive collapse. The software package LIRA version 10.12 was used. As a result of the calculations, the required reinforcement areas of the first-floor slab were determined.

Results. The required reinforcement area of the GFRP when calculated for resistance to progressive collapse in a quasi-static formulation, with a dynamic factor of Kdyn = 1.444, exceeded the area when calculated for the main combination of loads by 7.46 %. The required area of the upper reinforcement of the ASK, calculated for the main combination of loads, exceeded the area of the A500 steel reinforcement by 39.35 %. When calculating for progressive collapse, the difference decreased to 17.68 and 15.32 %, respectively, for calculations in a quasi-static formulation with the values of the dynamic factors Kdyn = 1.444 and Kdyn = 2.

Conclusions. The proposed combined reinforcement of floor slabs, taking into account the calculations for resistance to progressive collapse, allows for more efficient use of FRP reinforcement.

Introduction. Modern construction practice in areas with permafrost soils (PS) shows that the most rational principle for the construction of foundations for highways in the area of prospective development of the territories of the Arctic zone is the preservation of soils in a frozen state (the so-called I design principle). This is primarily due to economic considerations, since soil thawing is a costly technology, and its use is justified to some extent only in the area of island occurrence of permafrost soils.

Materials and methods. In order to meet the regulatory requirements for the strength and deformations of the pavement in the PS areas, it is necessary to perform a joint calculation of three physical fields — thermal, hydraulic and mechanical, that is, to perform a thermohydromechanical (THM) calculation. Such calculations, which are absolutely necessary for the design and assessment of conformity during the construction of roads in permafrost areas. At the same time, only separate methods of calculating the thermal condition of roads at PS are currently used in practice, after which the usual methods of calculating the mechanics of multilayer road structures are further applied. In this paper, the authors used the Plaxis 2D finite element (FE) software package, which is widely used for calculations of building structures, to perform joint THM calculations.

Results. The paper presents the results of the conducted research, on the basis of which recommended FE models have been developed for the joint THM calculation of embankments of highways in the PS areas. Concrete examples show that these models make it possible, in particular, to determine the optimal location in the body of the embankment of the XPS thermal insulation board layers used for thermal insulation. The data from the FE model also make it possible to study the fields of deformations and fields of water filtration rates during the defrosting of the embankment – base structure.

Conclusions. This study shows the possibilities of developing FE models for the joint thermohydromechanical calculation of highway embankments in permafrost areas using the Plaxis 2D software package. Concrete examples show that these models make it possible, in particular, to determine the optimal design of a highway embankment in permafrost areas in the presence of PS when used for thermal stabilization of XPS-type insulating plates in the embankment body. The studies carried out on the developed FE models have shown that these models also make it possible to study the fields of deformations and fields of water filtration rates during the thawing of the embankment – base structure, which makes it possible to conduct research on various road structures designed to operate in the Arctic zones at PS.

Introduction. Long-term operation of steel trusses in aggressive environments is accompanied by corrosion-induced degradation of the rod elements, which leads to reduced load-bearing capacity and an increased probability of failure. Deterministic approaches to service-life assessment often produce overly conservative predictions and do not account for the stochastic nature of damage evolution. The aim of this study is to develop and verify a probabilistic methodology for assessing the condition and residual service life of a steel truss structure while accounting for spatially heterogeneous corrosion.

Materials and methods. A finite element model of a typical truss was implemented in ANSYS Mechanical (SHELL181 elements), with segmentation of profile walls to simulate local degradation. The corrosion process was represented by discrete damage states within a Markov framework; transitions between states were modeled using probabilistic laws and the Monte Carlo method. The algorithm was implemented as a specialized Python script integrated into the ANSYS computational workflow, with stepwise geometry updates, mesh regeneration, and recalculation of the stress-strain state.

Results. For a 70-year time horizon, the following values were obtained: a safety factor of 2.8, a failure probability below 10–4, and a residual service life exceeding 25 years. It is shown that accounting for the probabilistic nature of state transitions and the spatial variability of corrosion significantly affects stress distribution and reliability estimates compared with simplified deterministic schemes.

Conclusions. The proposed methodology provides a quantitatively substantiated forecast of degradation and can be applied to planning monitoring programs, repair scheduling, and safety assurance measures for steel truss systems.

Introduction. The development of a research methodology aimed at controlling the structural formation of cementitious composites is a pressing challenge in modern concrete technology, which involves multi-component mixtures and additives. Addressing this challenge requires the application of methods for the quantitative assessment of structure and properties at various scales and stages of structural formation. The aim of this work is to develop a research methodology based on the analysis and identification of patterns in the formation of structure and properties at various scales and stages of structure formation, aimed at improving the efficiency of cement composite and concrete technology.

Materials and methods. The analysis of the structural formation of dispersed systems and cement composites was carried out using a fractal cluster model and percolation theory. The following physicochemical methods were employed: optical and electron microscopy, viscometry, and activity determination; as well as computer and mathematical modelling; and physical and mechanical testing.

Results. The paper outlines directions for the development of research methodology based on a systems approach, characterized by the application of a fractal cluster model, to establish quantitative indicators at various scales and stages of structure formation. A structural-phenomenological analysis of dispersed systems and composites has made it possible to refine and supplement our understanding of the mechanism of their structure formation. Quantitative relationships have been established between fractal-cluster processes at the micro-level and properties, taking into account the dispersion, nature and surface characteristics of the mineral components in cement composites. Based on a method for investigating structure formation at the meso- and macro-levels, which relies on geometric modelling of close-packed structures, the particle size distribution of aggregates has been adjusted to achieve a denser concrete structure.

Conclusions. This research methodology expands the scope for controlling the formation of structures and predicting the resulting structures of cement composites. Based on systematic studies ranging from the micro- to the macro-level, involving an assessment of the effective-ness of mineral components in organo-mineral additives, as well as the optimization of the particle size distribution of fillers, cement concretes with improved physical and mechanical properties have been produced.

Introduction. The disposal of industrial waste to produce a useful product is one of the basic tenets of the concept of sustainable development. In this regard, an urgent task is to study the production of binders and building products based on them from waste from metallurgical industries, which harden in the environment of carbon dioxide due to its absorption, while acquiring the necessary physical and mechanical properties.

Materials and methods. The main raw material component was nepheline sludge, a secondary raw material formed from nepheline concentrates of the Kola Peninsula during the production of alumina by the alkaline method. The crystalline phases were analyzed by measuring X-ray diffraction (XRD) on a Europe 600 (GNR) diffractometer. Thermal analysis to determine the mineralogical composition of nepheline sludge and artificial stone based on it was performed using a STA 8000 analyzer (Perkin Elmer). The dispersed composition of the nepheline sludge was determined by laser diffraction on a laser particle size analyzer Partica LA-960 (Horiba). Porosity was changed using the Automated Standard Porosimeter 3.2 (MPM&P Research Inc.). The mechanical characteristics of the prototypes were determined on an automatic servo-hydraulic MCS8 control console complete with software.

Results. Nepheline sludge consists of at least 85 % by weight from belite (β-C2S). It was revealed that the process of active CO2 absorption by nepheline sludge is observed in the first 120 minutes of carbonation. The compressive strength of the resulting material reaches 58 MPa, and after subsequent hydration, the strength increases to 70 MPa. The increase in strength is due to the formation of calcium carbonate in the carbonizing system. During subsequent hydration, gel-like hydration products of belite are formed, which additionally strengthen the carbonized material. Using the method of reference contact porosimetry, it was found that as a result of forced carbonation, the material is compacted, and the total porosity of the prototypes is significantly reduced. It is determined that the effective pore radii of carbonized specimens are shifted towards lower values in comparison with specimens not subject to carbonation, while this process takes place in the macropore region (0.1–16 µm).

Conclusions. Based on nepheline sludge, it is possible to obtain construction products that harden in a carbon dioxide environment due to its binding and subsequent hydration process, to obtain a material with high physical and mechanical properties.

Introduction. The purpose of this study is to develop an innovative building material with passive thermal regulation based on high-strength lightweight concrete on cenospheres using heat storage materials (HSM) stabilized in a carbon carrier (activated carbons). The researchers solved the problem of ensuring the functioning of the HSM in an environment with low thermal conductivity (in high-strength lightweight concrete with an average density of 1,400 kg/m3) while maintaining strength properties.

Materials and methods. The work used high-strength lightweight concrete on cenospheres with a density of 1,400 kg/m3. Coconut oil and polyethylene glycol (PEG) 600 were used as HSM. The HSM were stabilized in carbon carriers (activated carbons) of three grades: AC1, AC2 and AC3.

Results. The sorption capacity of the studied activated carbons was 80 % for PEG and 50 % for coconut oil. The average density of the specimens decreased to 1,320–1,390 kg/m3 at concentrations up to 2.5 %, while the thermal conductivity of the specimens with AC2 and AC3 increased to 0.58–0.60 W/(m·K). Also, the use of AC2 + PEG, AC2 + oil and AC3 + PEG
allows to preserve the physical and mechanical characteristics of concrete: flexural and compressive strength more than 4.3 and 41.8 MPa, respectively.

Conclusions. The use of AC2 to stabilize coconut oil and PEG, as well as AC3 to stabilize PEG in concentrations up to 2.5 % ensure efficient operation of HSM in an environment with low thermal conductivity (lightweight concrete) and allow sorption of up to 80 % PEG and up to 50 % coconut oil, which significantly exceeds the sorption capacity of widespread carriers for HSM. Also, one of the main advantages of the selected media is the preservation of high strength values of lightweight concrete during flexing and compression.

Introduction. In 3D construction printing, where large volumes of concrete are involved, it is necessary to allow for construction breaks and to divide the structure into sections; at the same time, the concrete mix must have time to develop its load-bearing capacity as the vertical elements are built up. The peculiarity of conducting work using this construction technology results in problems of forming “cold” joints associated with ensuring the strength of the adhesion of adjacent layers while simultaneously regulating the required rheological and technological parameters of materials for 3D printing. Most studies concern the operation of cement systems in comparison with gypsum systems due to the difficulties in regulating the setting time and water resistance of the stone. The main directions of research on viscosity modifier agents of mortar mixtures used in the construction market, as well as ways to increase the interlayer adhesion of fine-grained concretes for additive construction production, were considered. Active mineral additives are used to regulate the rheological properties of the mortar mixture. Organic additives can increase the strength of adhesion and adhesion, but require compatibility with other groups of additives. This requires studying the effect of an organic modifying additive and a hydrophobic agent on the adhesive strength with a concrete base.

Materials and methods. The preparation of the solution mixture and the aqueous solution of the organic polyfunctional additive was carried out according to the established mode, taking into account the complete dispersion of the modifying component in water during the subsequent production and storage of test specimens in accordance with the methodology regulated by regulatory documents.

Results. The test results indicate a decrease in the adhesion of the material to concrete when adding a viscosity modifier when used together with a hydrophobic agent, since the interaction at the interface of the mortar mixture with concrete does not ensure the formation of a physical and chemical bond. Also, when introducing a hydrophobic component into the composition of the mortar mixture, a plasticizing effect is observed with an increase in penetrating ability into the inner layers of concrete, which is indicated by changes in the predominantly cohesive nature of the destruction of specimens to adhesive with the appearance of areas with a type of tearing along the base material.

Conclusions. The relevance of ensuring the compatibility of an organic modifier and a hydrophobic agent to ensure the adhesive strength of the material in additive construction production is substantiated and confirmed. The relevance of the topic of further work lies in establishing a rational ratio of a hydrophobic agent and an organic additive to ensure high values of adhesive strength and penetrating ability of the mortar mixture.

Introduction. The possibility of replacing all types of aggregate in heavy concrete with crushed porcelain stoneware tiles (PST) is being considered. The work is carried out within the framework of cooperation with the enterprise for the production of sanitary products and porcelain stoneware — “Samara Stroyfarfor” LLC. The urgency of the task is to use this material as a component of the concrete mix, which in turn will help to free up space on the territory of the enterprise and lead to the return of production waste to reuse as a sought-after product. The main purpose of the study is to identify how the use of crushed PST will affect the physical and mechanical characteristics of concrete in comparison with “classical” aggregates.

Materials and methods. The main materials used were: Volga river sand with a grain size of 1.4; PST waste with a grain size of 2.1; crushed stone from dense rocks (manufacturer Orsky Crushed Stone Plant, branch of JSC PNK), fractions 5–20; crushed stone of sedimentary origin (manufacturer Ivanteevsky Stone Quarry), fractions 5–20 mm; PST waste, fractions 5–10 mm; the binder is Portland cement CEM II/V-W 42.5N; tap water.

Results. Several experimental studies were conducted to evaluate the possibility of using porcelain stoneware as a filler for concrete. The result of this work involved studying the basic physical and mechanical characteristics of concrete, such as density and compressive strength on cubic specimens. The hardening took place under normal conditions. The compressive strength of the specimens was determined at an intermediate age of 7 days and a design age of 28 days. In the process, optimal ratios of aggregates, both fine and course, in concrete compositions were identified.

Conclusions. The results obtained indicate the possibility of using a large granite slab in heavy concrete compositions without deterioration of their physical and mechanical characteristics, and in some cases their improvement, however, it should be noted that the use of waste from the production of crushed PST in its pure form is not advisable, both in the case of fine aggregate for concrete and coarse. Mixed with ordinary fine sand or crushed stone from dense rocks, concrete production in the construction industry can be fully established.

Introduction. In the Russian Federation, 1.5 million solid fuel boilers are in operation in individual heating systems. Given population density and economic factors, the use of solid fuel in individual homes in some regions will continue for a long time. The disadvantages of operating solid fuel boilers, such as the need for manual fuel loading, large storage space, excess capacity, and other issues, can be partially or completely resolved by using hybrid heating systems with solid fuel and electric thermal generators. The aim of the study is to determine energy efficiency, describe the operating algorithm of a hybrid system and automatic switching of thermal generators, assessment of greenhouse gas emissions, economic analysis of operating costs.

Materials and methods. Energy efficiency coefficient studies were conducted at the ARDERIA plant’s test facility using an Arderia EC 12 electric heat generator. Field tests of heat losses of wood-fired boilers in standby mode were conducted in the Moscow region at a real facility equipped with a Rojek KTP20 wood-fired pyrolysis boiler with a rated output of 20 kWh.

Results. Energy efficiency indicators for solid fuel heat generators, calculated for actual heating loads during the heating season and actual fuel, differ significantly from laboratory values declared by boiler manufacturers and, for heating systems without heat accumulators, amount to 50–65 %. Static losses of solid fuel boilers in standby mode without fuel combustion amount to up to 1.5 kWh.

Conclusions. The use of hybrid heating systems for individual homes with a heat carrier switching system solves the negative heat generation issues typical of solid fuel boilers. The economic costs of using solid fuel and electricity are comparable. The carbon intensity of thermal energy using electric heat generators is significantly lower than that of solid fuel boilers.

Introduction. The study aims to assess the effectiveness of raising the Volga-Kama cascade to its design levels. The relevance stems from the need to provide a basis for management decisions aimed at achieving sector-wide effects. The scientific novelty of this research lies in a comprehensive comparative analysis of various aspects of the project. The aim of the study is to determine the feasibility of raising water levels in the Cheboksary and Nizhnekamsk reservoirs to their design levels. The study examines the project’s effectiveness in terms of key benefits and costs, with a quantitative assessment of these across different scenarios.

Materials and methods. The source materials used include data from the technical and economic assessment of the completion of the Cheboksary Hydroelectric Power Station, official information on the operation of the Volga-Kama cascade, as well as regulatory, legal and strategic documents. Methods of economic evaluation of investment projects, scenario analysis and discounting were applied.

Results. The results demonstrate that restoring design water levels leads to a significant increase in hydropower generation and available installed capacity, removal of navigation depth constraints on the Unified Deep-Water System, reduction of recurrent dredging expenditures, and improvement of hydrological and ecological conditions in the reservoirs. For all considered scenarios, the aggregated intersectoral effect remains positive and substantially exceeds the outcomes associated with continued operation at non-design water levels.

Conclusions. The findings of the study indicate that raising the reservoirs to their design levels will have positive cross-sectoral effects. The project is feasible and should be implemented.

Introduction. Despite the successes achieved in the production activities of construction organizations, the further acceleration of their development is associated with the transformation of corporate culture, considering modern digitalization opportunities, ensuring technological sovereignty, and the formation of competitive advantages. This determines the urgency of solving the problem of choosing a direction for improving the corporate culture, adapted to the requirements of the period under review, based on the development of a methodological approach to managing the transformation of the corporate culture, taking into account the factors of the external and internal environment, and the development of a system of quantitative indicators to assess the readiness of construction organizations to transform the corporate culture.

Materials and methods. The solution of this task was carried out based on the use of such research methods as questioning and an integrative systematic approach that combines quantitative and qualitative methods of data analysis. Analysis of open information sources and data collection through structured questioning of personnel using a specially developed questionnaire made it possible to systematize the practical experience of interaction in the team of construction organizations depending on the specifics of production activities.

Results. As a result of the study, problem areas in the current state of the corporate culture of construction organizations were identified. This allowed us to outline the direction of the transformation of corporate culture, considering the strategic goals of the development of construction organizations and propose methodological solutions for its implementation. Based on an integrative system approach, combining quantitative and qualitative methods of data analysis, the task of forming a system of quantitative indicators to assess the readiness of construction organizations to transform corporate culture was solved.

Conclusions. The implementation of the chosen direction of transformation of the corporate culture of construction organizations, taking into account the factors of the external and internal environment, will ensure the achievement of the strategic goals of construction organizations, and the proposed system of indicators for assessing the readiness of construction organizations to transform the corporate culture will provide an objective assessment of the state of the corporate culture, which will make it possible to take reasonable managerial measures with an understanding of the scale and sequence of measures for its transformation.

Introduction. As-built documentation, including As-Built Inspection Certificates for concealed works, is a critical element of construction control, ensuring verification of quality and compliance with design and regulatory requirements. In the context of construction industry digitalization and the adoption of building information modelling technologies, reducing labour intensity and errors in the preparation of as-built documents becomes an important task. Despite the development of information modelling, practical solutions for the automated generation of certificate content based on a digital information model remain insufficiently developed. The purpose of this study is to develop and experimentally validate an approach to automating the generation of As-Built Inspection Certificates using a digital information model linked with a construction schedule (4D BIM).

Materials and methods. The study uses a building digital information model in IFC format, a construction schedule, and material specifications in tabular form as input data. The research applies methods of BIM data analysis, logical mapping between BIM elements and schedule activities, and algorithmic data processing using the Python programming language and open data exchange formats.

Results. A data model and an algorithm for automatic population of key fields of As-Built Inspection Certificates were developed. A software prototype of a certificate generator was implemented and tested on a pilot construction project. Quantitative performance indicators demonstrate a 3–4 times reduction in the time required to prepare a single certificate, a decrease in the number of errors to isolated cases, and an autofill completeness level of approximately 90 % compared to traditional spreadsheet-based and specialized software approaches.

Conclusions. The results confirm the feasibility and effectiveness of using 4D BIM for automating the preparation of as-built documentation. The proposed approach improves the reliability and transparency of certificates, reduces the impact of human factors, and can be recommended for implementation in construction control practice and common data environments of construction projects.