AlfaBuild

RAR RUS 2601-2601 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

Ivanitskii Artem Dmitrievich Bilateral Analytical Estimation of the Natural Oscillation Frequency of a Planar Triangular Truss The object of research is a statically determinate planar truss. The scheme of a lattice console structure in the form of a triangle is considered. Also, a structural feature is the presence of upper and lower belts, as well as braces. Method. The calculation of forces in the rods is carried out by cutting nodes from the solution of the system of equilibrium equations for all nodes in the projection on the coordinate axis. To derive formulas for the dependence of forces and the frequency of free oscillations, an inductive generalization of the sequence of solutions for structures with a different number of panels is used. The structural stiffness matrix is calculated using the Maxwell-Mohr formula in analytical form. Dunkerley and Rayleigh methods are used to find estimates of the lowest oscillation frequency of nodes endowed with masses. All mathematical transformations are performed in the Maple symbolic mathematics system. Results. Under the assumption that vibrations of loads concentrated in the nodes of the structure occur only along the vertical, and the rigidities of all rods are the same, compact formulas are obtained for upper and lower estimates of the first (main) frequency of natural oscillations of the system for an arbitrary number of panels. The upper estimate of the first oscillation frequency of the nodes has a rather higher than the lower estimate. The analytical solution is compared with the lowest oscillation frequency obtained numerically. The accuracy of the upper estimate of the frequency is very high and almost independent of the construction order. 10.57728/ALF.26.1 69 Truss Maple Analytical Solution Natural frequency Induction Symbolic solution Dunkerley method Rayleigh method Number of panels Maxwell – Mohr formula Lattice truss Planar truss https://alfabuild.spbstu.ru/article/2023.26.1/ 2601.pdf

RAR RUS 2602-2602 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

0000-0001-8619-2127 Fernando Marcelino Julio Vorobev Oleg Vladimirovich The lower limit of natural frequency and the oscillation spectrum of a planar truss The object of research is the frequency characteristics of a statically determined flat truss on two supports with a complex lattice and rectilinear horizontal chords. It is assumed that the mass of the truss is distributed uniformly over the nodes, and the stiffnesses of the elastic rods are the same. Method. According to the Dunkerley formula, an analytical estimate of the fundamental frequency of its natural oscillations is found. The vibrations of the masses are vertical. The forces in the rods are found by cutting out the knots. The rigidity of the structure is calculated by the Maxwell-Mohr formula. The generalization of a series of particular solutions for trusses with a successively increasing number of panels is carried out by induction using the Maple computer mathematics system. The common terms of the sequence of coefficients are determined from the solution of linear homogeneous recursive equations. To verify the solution, the fundamental frequency is calculated numerically as the first frequency of the spectrum. Results. Comparison of the analytical solution with the numerical one shows that the accuracy of the analytical estimate from below is quite high and increases with the number of panels. Spectral constants and isolines are found in the frequency spectra of a family of regular trusses. 10.57728/ALF.26.2 69 Truss Natural oscillation frequency Induction Maple Planar beam truss Dunkerley method Oscillation spectrum https://alfabuild.spbstu.ru/article/2023.26.2/ 2602.pdf

RAR RUS 2603-2603 0000-0002-0489-4107 Gorshkov Rostislav Alexandrovich 56227381900 0000-0003-2673-4566 Peter the Great St. Petersburg Polytechnic University Nemova Darya Viktorovna nemova_dv@spbstu.ru

St. Petersburg, Russian Federation

0009-0000-4772-4258 Frolova Irina Evgenievna Feasibility study when choosing a temperature schedule for heat load regulation The influence of the temperature of the mains water in the supply line on the technical and economic indicators of a heat energy source with an available capacity of 25 GCal/h with a qualitative method of regulating the heat load is evaluated. Three temperature control schedules were selected for comparative analysis: 150/70°, 130/70°, 110/70° without breaks and cuts. For each of the considered temperature graphs, the calculated flow rate of the coolant, the required diameters of pipelines, specific and total pressure losses in the system, the cost of pipelines, pumping equipment and installation work, the total cost of work on laying the turnkey heat network, the loss of thermal energy (power) through the insulation surface, the total annual loss of thermal energy are determined through the insulation surface at different temperature conditions. Based on the results obtained, it was found that the most optimal of the temperature regimes presented in the study is a temperature graph of 150/70°. 10.57728/ALF.26.3 69 Сentralized Heat Supply Heating Networks Thermal Insulation Heat Consumption Heat Load Temperature Graph https://alfabuild.spbstu.ru/article/2023.26.3/ 2603.pdf

REV RUS 2604-2604 0000-0002-7422-5494 Peter the Great St. Petersburg Polytechnic University Vafaeva KHristina Maksudovna vafaeva.khm@gmail.com

St. Petersburg, Russian Federation

0000-0003-3389-7742 Peter the Great St. Petersburg Polytechnic University Shinkareva Maria Konstantinovna shinkareva_mk@spbstu.ru The world experience in using fly ash as a secondary resource and features of its application in the Russian Federation: Overview The object of research is fly ash as part of ash and slag waste generated due to the production activities of thermal power plants, CHP. This work aims to systematize data on the volumes of fly ash generated as part of ash and slag waste, disposal methods, and a review of the world's experience in using fly ash to produce building materials. Research methods: overview literature sources, annual reports of energy companies, generalization, identification of potential uses of ash and slag, and the main obstacles. Results. The analysis of the Russian experience of industrial waste management shows the growing interest of the state and businesses in waste management methods. At the same time, the increase in processing volumes is limited by several regulatory, technical, and economic barriers. While studying scientific papers, it can be concluded that research mainly aims to improve the physical and chemical characteristics of materials using fly ash. With the complex use of ash and slag waste as secondary resources and the production of building materials, it is necessary to consider the different compositions of ash dumps. 10.57728/ALF.26.4 69 Ash and slag waste Ash and slag materials Ash and slag disposal Fly ash Ash dump https://alfabuild.spbstu.ru/article/2023.26.4/ 2604.pdf

RAR RUS 2605-2605 0000-0002-8080-9808 Rodin Alexander Ivanovich 0000-0002-2560-0948 Ermakov Anatoly Anatolyevich 0009-0006-9119-7268 Kravchuk Alexey Sergeevich Porous glass ceramics from siliceous rocks with the addition of magnesite The influence of MgCO3 in the composition of a charge of siliceous rocks, soda ash and potassium chloride on the phase composition, macrostructure and properties of porous glass-ceramic materials has been established. Samples of glass-ceramic materials were obtained by joint mechanochemical activation of components in a planetary ball mill followed by firing at a temperature of 820 °C. The effect of the amount of the additive on the phase composition of porous glass ceramics samples was established using the method of X-ray phase analysis (XRD). The developed materials have the form of blocks with a uniform fine-pored structure. With an increase in the amount of MgCO3 composition of the charge in glass ceramics, the amount of minerals diopside and combeite increases. The apparent density of the samples is in the range of 184–234 kg/m3, flexural and compressive strength is up to 1.57 MPa and 4.24 MPa, respectively, the thermal conductivity coefficient is 0.059–0.067 W/m∙°C. The developed materials are superior in many respects to foam glass and porous glass ceramics from industrial waste and can be recommended as thermal insulation in the construction of industrial and civil facilities. 10.57728/ALF.26.5 69 Porous glass ceramics Siliceous rocks Magnesite Apparent density Strength Thermal conductivity https://alfabuild.spbstu.ru/article/2023.26.5/ 2605.pdf