Vol 8, No 1 (2025)

Introduction. When designing a concrete composition depending on the type of structure, cement content is determined taking into account regulatory requirements for the minimum cement content depending on the operating environment. The maximum cement content is limited by economic indicators and technical conditions depending on the methods and conditions of work; the limitation on the amount of heat dissipation is not considered. Research objective: to develop a methodology for accounting for the heat dissipation of cement when assigning its consumption in concrete compositions for massive structures depending on their parameters and construction conditions. Methods. Experimental studies and analysis of regulatory documents and literary data on heat dissipation of cements and concretes. Modeling the parameters of temperature fields and stress fields depending on the class of concrete and its specific heat dissipation using the example of a foundation slab with specified dimensions and parameters of heat exchange with the environment. Results: An approach is proposed to standardizing the value of the maximum heat dissipation of concrete when designing a concrete composition for massive reinforced concrete structures. The article substantiates the position that the value of the level of tensile temperature stresses is less significantly affected by the concrete class than by its specific heat dissipation, since it is the heat dissipation of concrete that forms the temperature field and the temperature difference "center – top". Prevention of the risk of early cracking is associated not with slowing down heat dissipation, but with the value of specific heat dissipation, which determines the parameters of temperature fields, temperature gradients and stresses. The example shows that for a massive flat foundation slab with an accepted permissible level of tensile stresses of 0.67, the value of specific heat dissipation of concrete should not exceed 140 mJ / m3. A principle is proposed for determining the maximum class of concrete for compressive strength depending on the properties of cement. A dependence between the level of tensile temperature-shrinkage stresses and the criterion of thermal crack resistance of Zaporozhets I.D., independent of the concrete class, is revealed.

In three-layer reinforced concrete structures, the inner and outer layers of concrete of different physical and mechanical characteristics have different coefficients of thermal conductivity and linear temperature deformation. During the operation of buildings and structures, due to the temperature difference in the thickness of the structure along the contact planes of the layers, shear stresses may occur, which leads to bending of the structure, an increase in its deflections and a decrease in crack resistance. In this regard, when designing and calculating such structures, it is necessary to take into account the operational stresses and deflections caused by the temperature difference in the thickness of the enclosing structure. Taking into account the fact that the cross-section of three-layer enclosing structures with a monolithic connection of layers includes various types of concrete and reinforcement, differing in the values of the initial modulus of elasticity, to solve the problem, the cross-section of the enclosing structure is reduced to a homogeneous one corresponding to the largest initial modulus of elasticity of the concrete of the outer layers. Studies have been carried out to identify the effect of the thickness of the enclosing structure on the change in deflection, depending on the temperature difference, and its share in the total deflection of the structure. Despite the fact that the calculation results revealed a slight increase in the total deflection, taking into account the proportion of deflection that depends on the temperature difference, the study allows us to increase the accuracy of the calculation. The tendency to reduce the material consumption of structures and, consequently, a decrease in the thickness of the structure can lead to an increase in the proportion of deflection, depending on the temperature difference, which must be taken into account when choosing design solutions.

An analytical dependence is presented for calculating the power of a heating system, taking into account the aerodynamics of the movement of air flows inside a heated room. The analytical dependence is derived on the basis of the theory of a two-zone mathematical model of a heated room. The method allows us to determine a rational way of organizing heating to ensure minimal transmission heat loss through enclosing structures, taking into account factors affecting thermal and air processes in a heated room and contributing to a decrease in the power of the heating system as a whole. The results of the analysis carried out on the regularity of the movement of air flows in a room divided into two control volumes (CV): upper and lower CV. A mathematical model of the processes of heat and mass transfer of a heated room in an administrative or residential building has been developed, which takes into account the heat exchange between the upper and lower CV. The physical picture of the distribution of air and heat flows in a heated room with a local heat source located in the window sill space of the heated room is analyzed. A method for calculating the power of the heating system is proposed, taking into account the nature of the aerodynamics of the distribution of air flows in a heated room. An analytical dependence for calculating the thermal power of a heating system is presented, taking into account the characteristics of the distribution of heat and air flows across two control volumes of the heated room.

School plays a key role in the development of a person's personality throughout their life. The educational atmosphere largely shapes behavior patterns, especially for children and adolescents. The foundations laid at an early age often become decisive for the further development of the personality. Today, approaches to the educational process have undergone significant changes. The article presents a methodology developed by the authors that allows assessing the quality of architectural spaces of educational institutions by four main parameters. This will allow obtaining an objective picture of the state of educational spaces and making adequate architectural and design decisions at the administrative level. This work is based on an integrated approach to assessing architectural space, developing universal assessment models that allow correlating different-quality characteristics of school subsystems into a single assessment system, which will allow obtaining a quantitative assessment of the state of spatial indicators of educational institutions. Methods for assessing architectural spaces of educational institutions suggest entering a new stage of designing specific schools, eliminating serious consequences of architectural and design errors with large budget losses when implementing poor-quality development scenarios. The priority task of reforming the system of public authority is to create a qualitatively new level of public administration efficiency, including in matters of spatial development of educational institutions and renovation of existing schools. Because of the study, the main criteria and indicators of the quality of the architectural educational space were developed. The matrix of criteria includes such evaluation blocks as safe environmental design; formation of space; inclusiveness; stages of the physical condition of the building. The evaluation criteria were tested and refined in schools of the Republic of Bashkortostan. The results of the project implementation are methodological tools for assessing the quality of architectural spaces of educational institutions, an application for assessing the initial level of quality of architectural space, modeling the architectural planning solution of an educational institution and estimate documentation at the stage of an application for major repairs.