Introduction. The optimal aeration regime and hygienic standards for the content of car emissions in the air of residential areas of cities are ensured by choosing rational solutions for the direction of the highway, planning, building and landscaping of transport communications. The purpose of this study is to investigate the patterns of exhaust gas dispersion by road transport on urban streets, with the development of urban planning measures to improve air quality and ensure a comfortable aeration regime in pedestrian zones and public spaces.

Materials and methods. Selection and chemical analysis of air specimens for toxic ingredients and anemometric surveys on highways and streets in a large city, modelling the process of dispersion of automobile emissions by green belts in an experimental site.

Results. The influence of planning and building techniques on the aeration regime and atmospheric air quality of urban streets was established. The gas-protective efficiency of green plantation strips of different designs has been determined. Formulas were proposed for calculating the reduction of carbon monoxide concentration by green plantation strips in pedestrian areas on urban roads and streets.

Conclusions. In areas of urban roads that are not connected to buildings, the most effective way to protect against gas emissions is to use dense planting strips. In built-up areas of city roads and streets, the maximum decrease in the concentration of ingredients in the pavement is observed when the height of the green belts is at the level of the middle floors of buildings. In areas of urban streets that are densely built up, the highest quality of air in pedestrian areas and public spaces is achieved by using planting strips with tall trunks and open undergrowth. In cities with low average annual wind speeds, street spaces are opened up on the windward side to reduce air pollution by using techniques such as end, point, and free-form construction.

Introduction. Calculation of the natural oscillation frequency is the basis of the study of structural dynamics and is usually based on numerical methods. In cases where the structure is statically determinate and has a periodic structure, analytical solutions are also possible for estimating the first natural frequency. The most well-known here are the Rayleigh method for estimating the frequency from above and the Dunkerley method, which gives an approximate estimate from below. In this paper, simple analytical estimates are derived for the dependences of the first oscillation frequencies of a flat truss on the number of panels and the parameters of the structure.

Materials and methods. A statically determinate beam truss has a rise in the middle part. A simplified version of the Dunkerley method is used for the analytical calculation of the first natural oscillation frequency. The forces in the rods included in the formula are calculated in symbolic form by cutting out nodes using standard operators of the Maple computer mathematics system. The Maxwell – Mohr formula is used to determine the rigidity of the structure. It is assumed that the truss mass is uniformly distributed over all its nodes. The induction method is used to generalize the sequence of individual solutions for trusses of different orders to an arbitrary number of panels. The formula for the second natural frequency is obtained by the three-point collocation method based on the condition of similarity of the curve of the first frequency dependence on the number of panels.

Results. Formulas for the first two frequencies of natural oscillations of the truss are derived. Analytical solutions are compared with numerical ones obtained for the entire frequency spectrum. It is shown that with an increase in the number of panels, the accuracy of the analytical solution increases.

Conclusions. The analytical method for estimating the first and second frequencies is applicable to solving problems on regular structures. The advantage of the method is that its accuracy is independent of the order of regularity of the structure. The simple form of the result allows it to be used to select the optimal parameters of the object without the use of labor-intensive computer calculations.

Introduction. In the context of building reconstruction with underground space development, monitoring foundation deformations is of critical importance. Traditional criteria based solely on settlement magnitudes and their relative non-uniformity do not fully capture the spatial distribution of deformations and their correlation with geotechnical and structural factors.

Materials and methods. A digital methodology for predicting deformations of the foundations of reconstructed buildings was applied, based on the approximation of settlement by cubic splines and subsequent analysis of its derivative functions (angle of inclination and curvature). The methodology includes: formalization of the algorithm for constructing continuous settlement profiles and calculating their derivatives from geodetic monitoring data; validation of the methodology using case studies of reconstruction projects in Moscow and St. Petersburg with varying excavation parameters, wall lengths and orientations, as well as geotechnical conditions; application of machine learning methods to identify relationships between excavation geometry, soil parameters, and observed deformations.

Results. The constructed fields of settlement and its derivatives made it possible to localize zones of maximum deformations between benchmarks and to record cases of exceeding normative threshold values. Machine learning methods demonstrated the ability to predict deformation parameters (C′, D′) from external data on geometry and soil properties, providing acceptable accuracy on a limited dataset.

Conclusions. The application of cubic spline approximation of settlements in reconstructed buildings with underground parts, along with the calculation of slope and curvature of the foundation base, expands the traditional analysis toolkit, enabling identification of local deformation zones inaccessible to linear approximation. Integration with machine learning algorithms offers prospects for predicting foundation behavior in new reconstruction projects with underground development under dense urban conditions.

Introduction. Harmonic longitudinal waves in semi-infinite discretely inhomogeneous viscoelastic rods composed of an arbitrary number of viscoelastic layers are considered. The aim of the study is to develop an analytical solution and to investigate the influence of the properties of layered materials and viscoelastic models on wave dispersion and attenuation, which is important for vibration processes.

Materials and methods. The method is based on the spectral representation of the equations of motion and is applied to the classical models of Kelvin – Voigt, Maxwell, and the Standard Linear Solid (SLS). Explicit complex dispersion relations, expressions for the damping coefficient, and criteria for the sharp increase in amplitude when a wave passes through layer interfaces were obtained.

Results. Dependencies of damping on the elastic modulus, density, relaxation/retardation times.

Conclusions. It is concluded that the proposed analytical approach provides a reliable basis for the targeted design of vibration-isolating metamaterials and seismic barriers with predetermined frequency characteristics.

Introduction. Timber-composite wall panels operating under the shear load are studied, the shear stiffness of which is due to the inclusion of sheathing due to their connection with the frame by semi-rigid deformable shear bonds. A numerical method for calculating the strength of the frame elements is proposed, determining the magnitude of displacements and the reduced shear modulus of the panel, taking into account the change in the stiffness coefficient depending on the direction of the resulting deformation vector of shear ties relative to the direction of the fibers of the wooden ribs of the frame.

Materials and methods. The method of solving the problem is based on the variational principle of structural mechanics, namely, the minimum of the total potential energy of the system in the deformed state. The deformation of the system is described by two independent parameters: the rotation angles of the cladding faces relative to the axis of horizontal and vertical ribs. These parameters are used to express the potential energy of deformation of the connectors, bending of the wooden ribs of the frame and the work of the external shear force applied at the level of the upper strapping. The sum of these angles and the shear angle of the sheathing gives the angle of inclination of the racks to the vertical axis, through which the magnitude of the panel shear deformation is determined.

Results. The calculation of a three-layer timber-composite wall panel is presented. A symmetrical wall panel with a size of 1.5 × 3 m with a double-sided sheathing made of plywood sheets with a structural thickness of 12 mm is considered, the fastening of which to the wooden ribs is carried out by flexible mechanical connections. The application of an iterative approach to determine the real stiffness coefficients of the connectors is shown. It is found that the magnitude of shear depends to a large extent on the stiffness of the bonds and practically does not depend on the dimensions of the cross-section of the wooden ribs of the frame.

Conclusions. Wall panels with sufficiently rigid, frequently installed shear ties can have significant shear stiffness and can be used as vertical diaphragms as an alternative to massive and expensive CLT and MHM panels in the construction of low- and mid-rise timber buildings.

Introduction. Given the wide range of asphalt concrete mixtures covered by the updated regulatory framework, the organic and mineral content may vary, and their impact on capsules added to a standard organomineral system may also be variable. This study aims to establish the boundary conditions for the use of a modifier in the form of capsules containing a restoring agent in asphalt concrete mixtures with varying particle size distributions and bitumen binder contents.

Materials and methods. The particle size distribution of the mineral framework were studied in accordance with the requirements for stone-mastic asphalt concrete mixtures according to GOST 31015–2002, GOST R 58406.1–2020 and GOST R 58401.2–2019, as well as hot asphalt concrete mixtures according to GOST 9128–2013, GOST R 58406.2–2020 and GOST R 58401.1–2019.

Results. An approach is proposed that can be used to assess the suitability of asphalt concrete mixtures at the design stage of
the mineral component, taking into account the geometric dimensions of the encapsulated modifier used. The number of capsules depends on the residual porosity of the designed asphalt concrete, which must be taken into account when selecting the composition and compacting the asphalt concrete mixture.

Conclusions. The required mineral framework structure for using the self-healing modifier in the form of capsules with a diameter of 1.1 mm is required for mixtures based on a mineral framework with a maximum size of at least 10 mm. Such mixtures include stone mastic asphalt concretes SHMA-20 and SHMA-15, which meet the requirements of GOST 31015; SHMA-22, SHMA-16, and SHMA-11, which meet the requirements of GOST R 58406.1; SMA-22 and SMA-16, which meet the requirements of GOST R 58401.2; as well as hot-mix asphalt concretes A22Vt and A16Vt, which meet the requirements of GOST R 58406.2; SP-32, SP-22, and SP-16, which meet the requirements of GOST R 58401.1. With some grain compositions, near the maximum permissible limit, voids may form in the frameworks with sufficient volume to accommodate capsules in mixtures of type A, type B, type B, A11Bt and SP-11.

Introduction. Civil buildings have ventilation problems associated with inadequate air exchange and high heat loss. One solution to these problems is the use of decentralized compact reversible ventilation units with an exhaust air heat recovery function. They are called stationary switching regenerative heat exchangers (SSRHE). SSRHE provide a high degree of energy saving with low air flows. When using SSRHE, the issue of the effectiveness of air exchange and air distribution in the room is important. Therefore, a study was conducted to assess the mobility of air in the premises of typical apartments when using such devices at various characteristic air flow rates.

Materials and methods. The CFD method of modelling the operation of mechanical supply and exhaust ventilation based on a compact regenerator in a two-room apartment is applied. The Ansys Fluent software package was used for modelling. The isothermal formulation of the problem is considered. The turbulence model is adopted by k–omega (k–ω). 

Results. The distribution fields of air velocity in the plan of rooms at different heights with different characteristic air flow rates are presented. An increase in indoor air mobility is shown with an increase in ventilation performance. The combined effect of mechanical decentralized ventilation and natural centralized exhaust ventilation of residential buildings is shown.

Conclusions. Based on the simulation results, it was determined that when using ventilation devices of the SSRHE type, it is possible to ensure the required air mobility in the premises, which contributes to effective air exchange. It is determined that the permissible indoor air mobility is set for air flow rates in the range of 50–100 m3/h. The results of the study can be used in the design of mechanical ventilation systems for residential multi-apartment buildings based on compact SSRHE-type installations, as well as in the combination of natural and mechanical ventilation. In the future, it is necessary to conduct a study of air distribution for other types of apartments, which will expand the database to develop recommendations and create a methodology for designing ventilation systems based on compact reversible devices. Experimental confirmation of the simulation is also required.

Introduction. In modern construction, mechanical ventilation systems are becoming increasingly popular. Given the high-pressure losses in the shaped elements of ventilation systems, it is necessary to improve their design geometry. This is especially true for supply ventilation system tees, where flow separation occurs, leading to significant energy losses due to flow deformation. The aim of the study is to numerically simulate air flow in a symmetrical square-section supply tee to determine the local resistance coefficient, to determine the contours of vortex zones at the point of air flow separation and the local resistance coefficient of an optimized supply tee constructed taking into account the contour of the vortex zone in the flow
deformation area.

Materials and methods. The pressure loss coefficient of a standard symmetric supply-air tee, the area of vortex zone formed in the flow separation region, and the pressure loss of an optimized tee were investigated using computational fluid dynamics (CFD) in COMSOL Multiphysics 5.6. The Reynolds-averaged continuity and Navier – Stokes equations were solved with the standard k–ε turbulence model incorporating wall functions.

Results. The value of the pressure loss coefficient of a standard tee showed close agreement with previously published data. The tee construction was optimized with consideration of the vortex zone in the deformation region by rounding the wall, with subsequent numerical investigation.

Conclusions. The study demonstrated that rounding the wall in the flow deformation zone of a standard supply-air duct tee reduces hydraulic resistance by 11.9 %. The results contribute to both scientific understanding and practical applications in the development of optimized tee.

Introduction. The relevance of the study is due to the need to improve the efficiency of the technical customer at the stage of commissioning a construction project. The previous research demonstrated the possibility of using a parametric neural network model to assess efficiency, but the problem of detailed regulation of management processes and a clear definition of the functions of the technical customer at various stages of the life cycle (LC) remains unresolved. Modern construction projects require the coordination of multiple participants under strict time and budget constraints, placing high demands on the quality of management decisions made by the technical customer during the preparation and commissioning of the project. Business analysis and process modelling methodologies help overcome this problem by systematizing and optimizing management processes, identifying bottlenecks and duplication of functions, and ensuring the timely commissioning of the project. While there are developments aimed at structuring individual stages of construction production, less attention is paid to the comprehensive description and optimization of the entire cycle of technical customer management decisions using modern digital transformation tools.

Materials and methods. System analysis, comparative analysis, synthesis, parametric modelling, and the analogy method were used.

Results. A detailed BPMN model of the management decision-making process was developed, identifying participant roles, decision points, and feedback loops for cyclical performance adjustments. Mechanisms for integrating the process model with a parametric neural network model and the ability to connect BIM data for automation were proposed.

Conclusions. The use of BPMN 2.0 reengineering methods systematizes the technical client’s activities, ensures process transparency, clear assignment of responsibilities, and the ability to regularly optimize through the implementation of corrective organizational proposals. Using management models as a basis for developing information systems helps bridge the gaps between process design and practical implementation. The integration of BPMN models with artificial neural networks and BIM systems opens up the prospect of fully automating control and regulatory processes in construction.

Introduction. The high depreciation of public infrastructure facilities is due to inefficient life cycle management, in particular outdated approaches to planning operational activities. This study aims to address the current fragmentation of information systems and the isolation of the operational process from other lifecycle stages. The research focuses on digital master planning as a tool for creating a unified digital platform to support decision-making at all stages of the utility infrastructure lifecycle. The study’s objectives included a comparative analysis of utility network maintenance management systems and the compilation of a list of key attributes necessary for creating a data register and crucial for predictive planning.

Materials and methods. The study is based on a systematic analysis of current regulatory documents and scientific publications in the field of digitalization of operational processes. Using a SWOT analysis method, a comprehensive study was conducted of the challenges, benefits, risks, and prospects of applying digital master planning for key stakeholders in the lifecycle stages. The paper proposes evaluating the effectiveness of a unified digital platform using a linear convolution method.

Results. A system of criteria for multi-criteria evaluation of the effectiveness of digital master planning during the operational phase of utility infrastructure has been developed. A flowchart for a unified digital platform for asset lifecycle management has been created, and recommendations for its implementation have been formulated.

Conclusions. The significance of the proposed unified digital platform lies in its ability to bridge the gap in the lifecycle management system for utility infrastructure. The proposed solution will systematize large streams of real-time data, expanding analytical capabilities and technical condition forecasting. This is expected to reduce the time it takes to identify and resolve operational issues, improve the reliability of utility infrastructure, reduce resource losses, and ensure their quality.