Introduction. The formation of a monolithic frame of multi-storey buildings is one of the most resource-intensive and technologically complex processes of modern construction. The effectiveness of monolithic structures is influenced by the features of technological operations, the organization of the construction flow, the level of mechanization, as well as the quality of design solutions. The problems associated with an increase in the duration of the construction cycle, an increase in material consumption and the risk of technological defects remain significant, which requires a scientific justification of approaches to improving monolithic house construction technologies.

Aim. To determine the directions of increasing the technological efficiency and manageability of the processes of constructing monolithic frames of buildings by improving organizational and technological solutions, introducing digital tools and a comprehensive assessment of the manufacturability of design solutions.

Materials and methods. The research uses methods of system and structural analysis, technical and economic comparison of various organizational and technological schemes. Normative, design and scientific sources reflecting modern trends in the development of monolithic housing construction are used.

Results. The key factors determining the technological efficiency of monolithic structures construction, including the quality of formwork systems, the rationality of reinforcement solutions, concreting parameters and the organization of the construction flow, have been identified. The limitations of the existing practice have been identified, leading to a decrease in the pace of work and an increase in the risk of technological defects. Promising areas of improvement of monolithic construction technologies are substantiated: optimization of formwork and reinforcement processes, implementation of automated systems for monitoring concreting parameters, integration of BIM modeling with production and logistics operations.

Conclusions. It is shown that the implementation of the proposed organizational and technological measures helps to reduce the time required for the construction of a monolithic frame, increase the reliability of structures and improve the economic performance of construction. The research results have practical significance and can be used in the development of design solutions, organization of construction production and modernization of technological processes of monolithic housing construction.

Introduction. Connection between components of composite steel and concrete structures is the most important task in their design. Currently, a new type of anchors is popular in foreign design practice, made of reinforcing bars passed through holes in the walls of steel profiles – reinforced concrete dowels. The advantages of this technical solution are independence from the manufacturer of the anchors, relative simplicity and the absence of welding processes. It is also important to use reinforced concrete dowels in slim floors where the height of the reinforced concrete slab is close to the height of the steel beam.

The aim of the work is to develop a method for calculating reinforced concrete dowels connection.

Materials and methods. The engineering methodology based on the results of experimental research and analysis of existing international experience in calculating reinforced concrete dowels connection.

Results. The models are described; the features of the models, materials and their characteristics are given. The description of experimental equipment, schemes of testing and loading of structures are given. Schemes and types of fracture, graphical results tests of models are presented. A comparison of theoretical and experimental data is performed.

Conclusions. The main factors in determining the bearing capacity are the diameter and strength of the reinforcing bars. An almost direct relationship has been obtained between the diameter of the reinforcing bar and the bearing capacity of the model. Reinforced concrete dowels in composite steel and concrete beams make it possible to reliably combine the steel and reinforced concrete parts of the composite structure. Dowels can withstand significant loads up to 40–50 mm displacement deformations.

Based on the experimental studies carried out, an engineering methodology has been developed for calculating the strength of reinforced concrete dowels in composite steel and concrete beams.

Introduction. According to the recommendations, the calculation of reinforced concrete slabs with a steel profiled deck during the operational stage is performed based on the limit states. However, in order to solve a number of problems, it is necessary to know not only the limit state, but also the stress-strain state of the sections at each stage of loading. In SP 63.13330.2018, in addition to the calculation of normal sections based on the limit forces, there are also deformation methods with an analytical dependence of the curvilinear deformation diagrams of concrete in the form of ^σ_b = ^γ_b^E_b^ε_b. At the same time, the iterative methods used in the calculation of the maximum curvature of a bending element are quite time-consuming, even when using simplified deformation diagrams of concrete and reinforcement.

Aim. Development of an engineering deformation method for assessing the stress-strain state of reinforced concrete slabs with external reinforcement. Comparison of the results of calculation using the engineering deformation method and the method of calculation based on limit states.

Materials and methods. For a T-section element with external reinforcement, a system of nonlinear algebraic equations is written under the condition of dividing the vertical corrugations of the corrugated sheet into n layers, followed by the determination of stresses in an arbitrary layer as in multi-row reinforcement. The conditions of equality to zero of the sum of projections of all forces on the longitudinal axis and the sum of bending moments relative to the neutral axis are written depending on the position of the neutral axis in the design section.

Results. Examples and a comparison of the results of calculation of normal sections of reinforced concrete slabs with external reinforcement by the deformation method with the construction of the «moment-curvature» dependence and the method of calculation by limit states are given.

Conclusions. The proposed engineering deformation method provides a unified approach to calculation by limit states of the first group depending on the type of stress state: bending, eccentric compression at various eccentricities, and is distinguished by clear basic premises, greater simplicity and accessibility, both for designers and students.

Introduction. Concrete creep is a defining factor in the analysis of the stress-strain state (SSS) of reinforced concrete structures, causing increased deflections and intense stress redistribution between concrete and reinforcement. Traditional calculation approaches using the Non-linear Deformation Model (NDM), based on simplified adjustments to concrete stress-strain curves, have limited applicability when calculating systems with complex loading histories, in stress relaxation problems, and when modeling strengthening under load.

Aim. To develop and verify numerical algorithms for accounting for creep within the NDM structure based on a creep measure, ensuring the separate isolation of instantaneous and long-term strain components. Materials and Methods. An approach is proposed that is implemented at the level of elementary section areas by introducing creep in the form of initial strains. Three algorithms were developed, differing in the scheme of rheological process approximation: direct iterative accounting, integral accounting using the trapezoidal method, and step-bystep time integration with sequential updating of reference stresses. Numerical implementation was carried out in the “NDM+” software complex. Verification was conducted based on test results of 16 axially compressed reinforced concrete prisms (Ghent University) conducted over 12 years, with varying reinforcement percentages (0–6 %) and average concrete stress levels (0–15 MPa).

Results. Comparison with experimental data showed that algorithms based on the trapezoidal method ensure high accuracy (error 1–7 %) throughout the entire observation interval (4000 days). It was established that simplified iterative accounting leads to an underestimation of strains at late stages by up to 12 % due to the accumulation of methodological error during stress relaxation approximation. The nature of force redistribution was numerically confirmed: for specimens with moderate reinforcement, an increase in reinforcement stresses of up to 2.36 times was recorded, with a simultaneous decrease in concrete stresses by a factor of 1.2.

Conclusions. The developed algorithms represent an advancement of the provisions of the non-linear deformation model, offering a tool for a more detailed SSS analysis of structures constructed in stages or strengthened under load. The proposed approach complements existing engineering methodologies, ensuring a more rigorous physical accounting for the separation of strain components and providing engineers with flexibility in using various rheological models.

Introduction. The use of new types of reinforcement is based on research and justification of the effectiveness of their use in the design and construction of real buildings and structures. Currently, the most commonly used type of reinforcement in the construction of buildings is A500C according to [1] GOST 34028–2016, which has a “sickle-shaped profile.” At the moment, the market has an innovative reinforcement profile, which, while maintaining the strength characteristics, provides better adhesion to concrete, this is a new four-row type of reinforcement Av500P with a two-way screw rolling profile according to [2] STO 36554501–068–2022. The new helical profile, according to [2], has a uniform distribution of wedging forces from the reinforcement surface, which results in better adhesion to concrete. The calculation of structures uses the recommendations of STO 36554501–068–2022 [2] for calculating the crack opening width of reinforced concrete foundation slabs and floor slabs.

The aim of this study is to identify the effectiveness of using Av500P reinforcement compared to A500C reinforcement. A 10-storey apartment building in Sochi was considered. Two calculations were performed to compare the metal consumption for the foundation slab and the floor.

Materials and methods. The project of a 10-storey apartment building in Sochi was considered. Two calculations were performed to compare the metal consumption for the foundation slab and the floor.

Results. When replacing A500C reinforcement with Av500P reinforcement in the foundation slab and ceiling, the consumption was lower.

Conclusions. The effectiveness of using the innovative Av500P reinforcement profile has been revealed in comparison with the conventional A500C reinforcement profile.

Introduction. Concrete shrinkage is a key factor in the durability and crack resistance of reinforced concrete structures. Despite many years of research, issues of quantitative prediction and assessment of shrinkage cracking remain relevant, especially given the construction industry’s transition to low-water-cement ratio concrete and the extensive use of superplasticizers.

Aim. To summarize current understanding of the mechanisms, types, and methods of measuring concrete shrinkage, critically analyze regulatory testing procedures, and identify areas for improving calculation models. Materials and Methods. An analytical review of domestic and international publications from 1975 to 2025 was conducted, including an analysis of domestic standards (GOST 24544–2020, SP 63.13330, etc.) and international regulations (ModelCode 2010, ACI209R 22). Comparative analytical and systematic methods were used, supplemented by a summary of experimental data from research groups, including results from 2 022 to 2025.

Results. A fundamental duality in the nature of shrinkage was revealed: autogenous, caused by self-compression of the hydrating cement stone, and drying, caused by moisture migration. It was shown that at water-cement ratios  0.35, the autogenous component reaches 55–65 % of the total shrinkage by the 28th day, and its rate is proportional to the specific surface area of the cement. The role of moisture and temperature gradients in creating uneven stress states is examined, and the need for a comprehensive accounting of shrinkage and creep in one-dimensional stiffness models is substantiated. Laboratory and field methods (contact, non-contact, and interferometric) are systematized, and their metrological limitations are  demonstrated.

Conclusions. Modern design practice requires a transition from limiting standard values to predictive models that take into account the actual moisture-thermal state of a structure and concrete formulation. The integration of sensor systems for online deformation monitoring and the validation of calculated shrinkage curves for high-strength and composite concretes offer promising prospects. 

Introduction. The technology of floating caissons and reinforced concrete hulls has undergone a long evolution, beginning with the early engineering solutions of Julius Caesar during the siege of Brundisium and the subsequent construction of port facilities in Ancient Rome. In the 20th century, reinforced concrete began to be used in shipbuilding, particularly in conditions of metal scarcity, leading to the creation of floating docks, barges, and vessels for various purposes.

Aim. To analyze the historical development and contemporary advances in floating caissons and reinforced concrete vessels, including the use of lightweight and ultra-high-performance concrete (UHPC), and to assess the prospects for their application in specialized maritime and coastal structures.

Materials and methods. The study is based on historical and contemporary analyses of construction and technical data, project documentation, and publications, as well as on case studies of structures ranging from the first concrete vessels of the 19th–20th centuries to modern barges and caissons (SS Atlantus, Larinda, Nkossa, the Marseille caisson gate, Kislogubskaya PSP). Methods included comparative analysis of structural solutions, materials, and technologies, as well as evaluation of the advantages and limitations of reinforced concrete floating structures.

Results. The historical review demonstrated a gradual improvement of designs, increased strength, and enhanced resistance to marine environmental effects. The use of lightweight and ultra-high-performance concretes (LWC, UHPC) allows for a reduction in hull weight, increased buoyancy and load capacity, and improved crack resistance and durability. Modern technologies, including fiber-reinforced concretes and 3D printing, open new possibilities for modular and specialized shipbuilding.

Conclusions. Reinforced concrete and concrete floating structures remain relevant for specialized objects such as floating platforms, bridges, pontoons, and temporary facilities. The use of lightweight and ultra-high-performance concretes expands design possibilities, improves costeffectiveness, and enhances operational reliability, making these technologies promising for modern maritime and coastal engineering solutions.

Introduction. It is a well-known fact that the higher the density of lightweight concrete (mortar) in the solidified state, the higher its strength. Thus, according to [1], at an average concrete density of 700–1100 kg/m³ (D700–1100), the strength of light concrete varies in the range of classes B3.5–B7.5, and at a density of 1200–1400 kg/m³ (D1200–1400), the strength corresponds to classes B3.5 to B25. Light mineral plasters in general can be attributed to light fine-grained concretes and, therefore, they must obey the same strength-density relationships, component consumption as light concretes (the higher the density, the greater the strength of the plaster solution). In this work, a study was conducted of light plaster based on white Portland cement and a mineral filler – foam ceramic granules “SPADAR”, for the effect on the strength of the plaster solution of its density and consumption of the main components (cement, foam ceramic filler “SPADAR”, water).

Aim. To study the dependence of the axial compressive strength of light mineral plaster based on white Portland cement and foam-ceramic granules “SPADAR” on its density and consumption of components (cement, foamceramic filler “SPADAR”, water). The range of densities for determining the strength parameters of plaster was selected by the following brands: D400, D500, D600, D700, D800.

Materials and methods. For the research, samples were used 7 x 7 x 7 cm cubes made of a light plaster mixture “SPADAR” with dry densities of 400, 500, 600, 700, 800 kg/m³ and hardened under normal conditions for 28 days. The density of dry plaster was determined by State Standard 5802–2024 “Construction solutions. Test methods”. The compressive strength of the plaster mortar was determined according to State Standard 5802–2024 [3] on 7 x 7 x 7 cm cube samples. The dependence of the strength of the solution on the consumption of its components was determined by the mathematical and statistical method.

Results. During the work, the dependence of the axial compressive strength on the density of the plaster mortar was experimentally established. As the density of the solution increases, so does its strength. The dependence of the strength of the solution on the consumption of cement and water and the density of the solution is calculated using a mathematical and statistical method. Thus, it was found that with an increase in cement consumption from 185 to 435 kg per 1 m³ of mortar mixture, the strength of the solution increases from 1.5 to 8.5 MPa. At the same time, the density of the solution increases from 400 to 800 kg/m³. This is true for the consumption of foam granules in the range of 0.7–0.85 m³/m³ of solution.

Conclusions. Based on experimental data and mathematical and statistical calculations, it was found that with an increase in the density of the plaster mixture from 400 to 800 kg/m³, the strength of the studied solution for axial compression increases exponentially from 1.5 MPa to 8.5 MPa, while the consumption of binder and water increases. The consumption of SPADAR foam granules in the range of 0.7–0.85 m³/m³ of solution does not significantly affect the change in the strength parameters of the tested compounds. This study has found further practical application in the development of the composition of light plaster “SPADAR SK 750” with increased density and durability.

Introduction. This article continues the discussion. The LIRA-SAPR software package, widely used in Russia, is examined. Due to its many positive qualities, it is used by various design, educational, and regulatory organizations. However, the results of calculations for reinforced concrete structures raise the doubts and questions discussed in this article. Numerous requests to the developers for clarification, unfortunately, remain unanswered.

Aim. To verify the accuracy of the LIRA-SAPR software’s calculations for reinforced concrete structures.

Materials and Methods. Three test cases were considered: an experimentally verified floor slab, a foundation slab, and a slab from the LIRA-SAPR Software User’s Guide. The reinforcement of the structures was determined using LIRA-SAPR and compared with experimental data, as well as with the results obtained using the OM SNiP Zhelezobeton software using a nonlinear deformation model and the ultimate force method.

Results. The results of the LIRA-SAPR reinforcement calculations were, in our opinion, incorrect: the reinforcement consumption in these cases exceeded the standard requirement by several times – 3.8, 9, and 3.1.

Conclusions. Due to the significant, unjustified excess consumption of reinforcement, as demonstrated by the examples provided, the LIRA-SAPR program in its current form can only be used to determine forces, but not to calculate the reinforcement of reinforced concrete structures. We believe it is necessary to discuss this situation with the program’s developers and take measures to rectify it. The authors believe one possible solution is to use LIRA-SAPR only to determine forces, and to calculate the reinforcement for these forces using the OM SNiP Zhelobeton program, which takes into account all regulatory requirements. At the same time, it is necessary to note the need for further improvement of the standards. 

Introduction. The volume of construction waste in Russia reaches millions of tons per year, a significant part of which is ceramic bricks. Recycling of ceramic waste is a promising direction for improving environmental sustainability and reducing costs in construction. This paper reviews current research on the use of recycled ceramic materials as aggregates and binders in concrete.

Aim. The purpose of this review is to analyze the results of research published in the last five years on the effect of secondary ceramic materials on the physical and mechanical properties of concrete.

Materials and Methods. The results of several scientific studies on the effect of different proportions of replacement of traditional aggregates and cement with ceramic waste materials are reviewed. Data on concrete compressive, flexural, tensile strength, workability, thermal resistance, water permeability and durability are included.

Results. It was found that partial replacement of aggregates (up to 50 %) and cement (up to 15 %) with ceramic waste can improve the mechanical properties of concrete, in particular compressive and flexural strength. Thermal resistance increases, but there may be a decrease in flowability and an increase in water permeability. The optimum ratios depend on the fractional composition of the ceramic waste and its processing.

Conclusions. The use of secondary ceramic materials in concrete is a promising direction that contributes to reducing the cost of construction materials and improving their performance characteristics. For effective use it is necessary to take into account the substitution parameters and additionally apply modifying additives.