75504 2712-8172 5 121 2023 1-144

RAR RUS 12101-12101 56352359500 0000-0002-5156-7352 Volgograd State Technical University Sergey Korniyenko svkorn2009@yandex.ru

28, Lenina Ave., Volgograd, Russia, 400005

Volgograd State Technical University Dubov Igor dubov_i_architect@mail.ru

Volgograd, Russian Federation

Volgograd State Technical University Nazarov Konstantin nazkostja@gmail.com

Volgograd, Russian Federation

Field study of thermal comfort in dwelling during the winter, mid-season and summer This research focused on adaptive thermal comfort in dwelling in the cold winter and hot summer climate zone of Russia. A field study was conducted throughout the three seasons (winter, mid-season and summer) beginning in September 2019 and ending in June 2020 in Volgograd (48°43.164′N, 44°30.108′E), Russia. The survey included simultaneous measurements of outdoor and indoor environmental parameters and an assessment of the participants’ sensations using questionnaires. The living room and bedroom of an apartment building for a family with a child were chosen as the research environment for indoor physical parameters and for administering the questionnaires. Only free-running thermal environments were considered in this research. The sensation ratings were analyzed, and thermal comfort temperature was calculated using regression methods. Results showed that in winter there were deviations in the thermal sensation, satisfaction, expectation of residents, and that they preferred a neutral cold environment. There were differences between the mid-season results and those of winter and summer. The thermal comfort assessment in premises under continental climate conditions should be based on thermal adaptation models. We calculated that the acceptable temperature range for residents in winter was 17.5–22.5 °C, 20–25 °C (with acceptable deviation of 2.5 °C) in mid-season and 22.5–27.5 °C in summer. The actual indoor relative humidity was almost within the applicable ranges (30–60 %) as well. The ASHRAE55-2013 and EN15251-2007 adaptive thermal comfort models are suitable for premises in mid-season and summer. The predictions of both mid-season and summer models were reliable. The main solutions to improve the indoor temperature conditions include heat flux control in heaters within the apartment in accordance with the adaptation thermal comfort model, as well as control of natural ventilation in winter. In this case it is predicted, that the reduction of total heating load is 24.2 %. Indoor thermal neutral temperature at the small energy demand in premises can be obtained by implementing the smart home concept. These results can be used to assess indoor thermal comfort in dwelling and help create friendly and energy efficiency building environments in Russia. 10.34910/MCE.121.1 628.87 adaptive thermal comfort models dwelling climate zone neutral cold environment comfort temperature free-running thermal environments energy efficiency https://engstroy.spbstu.ru/article/2023.121.1/

RAR RUS 12102-12102 Peter the Great St. Petersburg Polytechnic University Minaev Oleg minaev.op@bk.ru

29 Politechnicheskaya St., St. Petersburg, 195251, Russia

Soil friction on a retaining wall under seismic load The paper is the first to establish that the classical quasi-static analytical calculation of the retaining wall for seismic load indirectly reflects the wave nature of the impact of the sandy backfill soil on the rear surface of a retaining wall. The evidence provided includes the comparative results of the designed gravity retaining wall made from reinforced concrete and having a front cantilever that consider and disregard soil friction under the calculated operational static and seismic loads. The calculations were carried out for given dimensions of the retaining wall and characteristics of sandy backfill soils on weak clay foundation soils. It is emphasized that the calculation results are quite consistent with the research data on the behavior of sandy soils in the plate base under dynamic wave loads. These results were used to obtain the dependence necessary for determining the angle of soil friction against the rear surface of the wall under seismic load of varying intensities. It seems quite convincing that the calculation of the retaining stack for a seismic load of 9 points can be carried out without taking into account soil friction, since in this case, under seismic action, soil slippage along the rear surface of the retaining wall is possible. With a seismic load of 7 and 8 (or less) points, the angle of friction of the soil against the rear surface of the retaining wall should be determined from the obtained dependence to determine the angle of friction of the soil under a seismic load of varying intensity given in this article. 10.34910/MCE.121.2 626/627:699.841:624.1 retaining wall active pressure soil friction dynamic load foundation bearing capacity stability wave action seismic intensity https://engstroy.spbstu.ru/article/2023.121.2/

RAR RUS 12103-12103 Institute of Mechanical Engineering Problems RAS – branch of Federal Research Center Institute of Applied Physics of the Russian Academy of Science Erofeev Vladimir erof.vi@yandex.ru

Nizhny Novgorod, Russian Federation

56431034200 0000-0002-5802-8773 Nizhny Novgorod Statе Univеrsity of Arсhitесturе and Civil Еnginееring Monich Dmitriy dmitriy.monich@mail.ru

Nizhny Novgorod, Russian Federation

Nizhny Novgorod Statе Univеrsity of Arсhitесturе and Civil Еnginееring Grebnev Pavel p.grebnev@mail.ru

Nizhny Novgorod, Russian Federation

Institute of Mechanical Engineering Problems RAS – branch of Federal Research Center Institute of Applied Physics of the Russian Academy of Science Pavlov Igor ispavlov@mail.ru

Nizhny Novgorod, Russian Federation

Calculation method for sound insulation of lightweight enclosures at low frequencies The objects of the study are lightweight enclosing structures (partitions) located between the premises of buildings. The surface density of lightweight fences lies in the range of 20 < μ < 100 kg/m2. The elaboration of methods for calculating the sound insulation of lightweight enclosures, taking into account geometric and physical and mechanical parameters, is an urgent task for building acoustics. The studies are carried out on the basis of the theory of self-consistency of wave fields with account of the resonant and inertial sound transmission through the enclosures. The article presents the results of theoretical studies of sound insulation of lightweight enclosing structures in the frequency range from 50 Hz to 5000 Hz. It was proposed to divide the generalized frequency characteristic of the sound insulation of lightweight enclosing structures into two ranges, the boundary between which is determined by the geometric sizes of the fence. Based on the theory of self-consistency of wave fields, a method was developed for calculating the sound insulation of lightweight enclosing structures in the frequency range above the threshold frequency of sound field diffuseness in the plane of the enclosing structure and below the threshold frequency. The method enables calculating the sound insulation of lightweight enclosures, the threshold frequencies of the areas of resonant sound transmission, as well as the frequency characteristics of the coefficients of resonant and inertial sound transmission. The implementation of this method is considered on the example of a lightweight frame-sheathing partition with anti-resonance panels. The authors obtained theoretical frequency characteristics of the coefficients of sound transmission through a lightweight frame-sheathing partition and the frequency characteristics of the sound insulation of the partition in the calculated frequency range. 10.34910/MCE.121.3 699.844 sound insulation enclosing structures of buildings lightweight enclosures frame-sheathing partitions anti-resonance panels resonant sound transmission inertial sound transmission self-consistency of wave fields https://engstroy.spbstu.ru/article/2023.121.3/

RAR RUS 12104-12104 6701544758 0000-0002-1756-3526 National Research Tomsk Polytechnic University Vakalova Tatiana tvv@tpu.ru

Tomsk, Russian Federation

57222054169 0000-0002-7656-5628 National Research Tomsk Polytechnic University Sergeev Nikolay axioma-13@yandex.ru

Tomsk, Russian Federation

0000-0001-8242-0655 National Research Tomsk Polytechnic University Tolegenov Dias www.dika-92@mail.ru

Tomsk, Russian Federation

National Research Tomsk Polytechnic University Tolegenova Diana diana_doni@mail.ru

Tomsk, Russian Federation

High-strength building ceramics based on fly ash – red mud mixtures The work is devoted to the actual problem of creating high-strength ceramic materials based on technogenic waste. This problem is solved by using low-calcium (2.26 % ) aluminosilicate fly ash from the combustion of solid fuel (coal) as the main raw material component with the additions of high-iron (22–25 %  in the calcined state) bauxite sludge. The chemical and mineralogical features of the initial fly ash and bauxite sludge, as well as their structural and phase changes during heating were studied. The predictive analysis of the behavior of ash and bauxite sludge mixtures in the , and  systems made it possible to identify the fluxing effect of bauxite sludge additions to fly ash. The main criteria for designing compositions (  and  modules) of ceramic masses based on ash and sludge for the production of high-strength ceramics are proposed. The iron-alumina module is responsible for the formation of the melt; the calcium silicate module is responsible for the formation of the crystalline phase (anorthite) during firing. The established sintering-hardening effect of bauxite sludge additives in an amount of 10–25 % in compositions with fly ash provides a 1.7–2-fold increase in the compressive strength of samples of semi-dry pressing (from 95 to 206 MPa) at firing temperatures of 1200 °C. The recommended compositions are promising for obtaining densely sintered calcium aluminosilicate building ceramics (paving stones, porcelain stoneware, clinker bricks) with a predominantly anorthite crystalline phase with a water absorption of 0.5–2 % and a compressive strength of up to 175–200 MPa. 10.34910/MCE.121.4 fly ash red mud sintering mechanical strength anorthite building ceramics https://engstroy.spbstu.ru/article/2023.121.4/

RAR RUS 12105-12105 57194112309 0000-0001-6184-2365 Vyatka State University Tyukalov Yury yutvgu@mail.ru Triangular prism finite element based on piecewise constant stress approximations The study object is a three-dimensional triangular prism finite element based on piecewise constant approximations of stresses. The use of such a finite element makes it possible to obtain more accurate stress values, especially at the boundaries of the region and in the stress concentration zones. The solution of the volume theory elasticity problem was obtained on the basis of the additional energy functional and the possible displacements principle. With the help of the possible displacement principle, algebraic equilibrium equations of finite element grid nodes are formed. The resulting equilibrium equations sum up with the additional energy of the system using the Lagrange multiplier method. In this case, the stresses are determined directly at the nodal points, and not at the finite element centers. The stress fields are continuous along finite element boundaries and discontinuous inside them. The paper shows that the displacements obtained by the proposed method, when refining the finite elements mesh, tend to exact values from above. As a test, the article provides calculations for bending plates and beams. As the test problems solutions showed, the proposed finite elements allow obtaining more accurate stress values compared to traditional finite elements based on stress approximation. Comparison of the stresses obtained by the proposed method with analytical solutions shows the high accuracy of the proposed method. 10.34910/MCE.121.5 69.04 finite element method stress approximation triangular prism piecewise constant stresses possible displacements plates beams https://engstroy.spbstu.ru/article/2023.121.5/

RAR RUS 12106-12106 55882885600 0000-0002-5806-7190 Gersevanov Research Institute of Bases and Underground Structures (NIIOSP), JSC Research Center of Construction Sharafutdinov Rafael linegeo@mail.ru

Moscow, Russian Federation

Clay soil stiffness under consolidated isotropic drained triaxial tests Triaxial tests are common laboratory methods to study the mechanical properties of soils. According to international practice, it allows determining the reliable strength and stiffness properties. This research paper describes the results of statistical analysis of the deformation parameters for clay soils obtained from triaxial tests. The research focused on clay deposits of the Quaternary, Jurassic and Carboniferous periods of diverse genesis. The results of 992 consolidated isotropic drained triaxial tests of clay soils in Russia (Moscow) and Belarus (Minsk) were analysed. More than 50% of the tests were carried out under unloading/reloading conditions. As a result, empirical equations enabling evaluation of the effects of physical properties and stress state on stiffness of clay soils with different age and genesis were proposed. Comparison of accomplished tests of Quaternary and Jurassic soils from Thailand, Europe and the USA showed that stiffness for overconsolidated soils is in the same range as soils from Moscow and Minsk sites. The performed studies revealed the values of the Hardening soil model m-parameter depending on soil forming factors and its preconsolidation degree. In overconsolidated soils, values of the m-parameter are on average twice less than in normally consolidated or lightly overconsolidated soils. Proposed equations can be applied for preliminary estimation of the stiffness parameters for finite element method calculation, as well as used in geotechnical models that allow variability, horizontal and vertical distribution of stiffness to be taken into account. In general, geotechnical engineers may utilize the obtained results by applying them to design of complex soil models. 10.34910/MCE.121.6 624.131 non-linear modelling numerical modelling clays laboratory tests triaxial test finite-element method statistical analysis stiffness Hardening Soil model https://engstroy.spbstu.ru/article/2023.121.6/

RAR RUS 12107-12107 57201680872 0000-0002-0903-3517 Karaganda Buketov University Akhazhanov Sungat stjg@mail.ru

Karaganda, Republic of Kazakhstan

M-6585-2013 6508103761 0000-0002-1196-8004 Peter the Great Saint Petersburg Polytechnic University Vatin Nikolai vatin@mail.ru

Polytechnicheskay, 29

57196147829 Abylkas Saginov Karaganda Technical University Akhmediyev Serik serik.akhmediyev@mail.ru

Karaganda, Republic of Kazakhstan

0000-0003-3346-4947 L.N. Gumilyov Eurasian National University (ENU) Akhazhanov Talgat talgat_a2008@mail.ru

Astana, Republic of Kazakhstan

57214108408 0000-0001-7909-7201 al-Farabi Kazakh National University Khabidolda Omirkhan oka-kargtu@mail.ru

Almaty, Republic of Kazakhstan

Al-Farabi Kazakh National University Nurgoziyeva Aizhan aizhanzhanabai@gmail.com

Almaty, Republic of Kazakhstan

Beam on a two-parameter elastic foundation: simplified finite element model When calculating beams resting on a solid elastic foundation, the simplest foundation models proposed by Winkler-Zimmerman and Vlasov-Leontyev are often used. These hypotheses have been repeatedly subjected to well-founded criticism, because they do not take into account the inclusion in the work of some areas of the base and do not allow determining reactive pressures at the ends of the foundation beam and beyond it. In order to clarify these hypotheses, many authors have proposed some other models that allow smoothing out the shortcomings of these models to varying degrees. This article proposes a new numerical approach to solving the problem of a beam on a two-parameter elastic foundation. To calculate the beam, the finite element method has been used. A separate rod has been proposed as a finite element for solving the bending state of the beam on a two-parameter model of an elastic foundation. There has been presented the construction of the stiffness matrix of this finite element. The elastic foundation is assumed to be linear, homogeneous and isotropic and is taken into account using the parameters r, s. The reactions of the elastic base, deflections and angles of rotation, the formulas for calculating bending moments and transverse forces have been determined. There have been given examples of static calculation of a beam on an elastic two-parameter foundation for the action of various loads. These examples demonstrate the effectiveness of the developed method. Reliability of the method proposed by the authors has been verified on test examples, and good agreement has been obtained with the well-known models of Winkler and Vlasov. 10.34910/MCE.121.7 624.1 beam elastic foundation finite element stiffness matrix finite element model Winkler model Vlasov model https://engstroy.spbstu.ru/article/2023.121.7/

RAR RUS 12108-12108 V.G. Shukhov Belgorod State Technological University Lesovik Valeriy naukavs@mail.ru Belgorod State Technological University named after V.G. Shukhov Popov Dmitry popov.dmitry412@yandex.ru

Belgorod, Russian Federation

57199850188 0000-0002-2279-1240 Far Eastern Federal University Fediuk Roman roman44@yandex.ru

8. Suhanova St. Vladivostok, st. Octyabrskaya. 690950. Russia

Peter the Great Saint Petersburg Polytechnic University Sabri Mohanad Muaya mohanad.m.sabri@gmail.com

Polytechnicheskay, 29

branch FGBU "TSNIIP Russian Ministry of Construction" DalNIIS Vavrenyuk Svetlana trusanova2014@mail.ru

Vladivostok, Russian Federation

Far Eastern Federal University Liseitsev Yuriy gera210307@ya.ru

8, Suhanova St. Vladivostok, st. Octyabrskaya. 690950. Russia

Shrinkage of ultra-high performance concrete with superabsorbent polymers During the period of hydration and hardening in ultra-high performance concrete (UHPC), a number of destructive processes occur that affect the formation of the structure of the material, which ultimately seriously affects its technical properties and performances. In this regard, the article explores the possibility of increasing the effectiveness of UHPC through the use of polymineral binders (PB) and superabsorbent polymers (SAP). For this, such characteristics as the effect of SAP on the plastic shrinkage of cement paste were investigated; hydration and hardening of cement in the presence of SAP; rheological and physical-mechanical properties of the cement system with the addition of SAP; shrinkage deformations of UHPC. It has been proven that SAP is an effective means of reducing shrinkage deformations of the cement system at the initial stage of structure formation, which helps to reduce the number of destructive phenomena of cement paste. The additive with a dispersion of more than 200 µm reduced vertical deformations by approximately 30%, and with a dispersion of less than 200 µm, by 50%. Despite the fact that SAP does not have a chemical effect on the process of cement hydration. However, the introduction of an additive in an amount of more than 0.1% by weight of PB leads to a significant increase in the setting time (period of active hydration) through the absorption and desorption of water. After 17 and 24 hours after watering, the crystals of neoplasms in the control samples without additives developed more rapidly and had a larger size. However, 41 hours after mixing with water, the larger size of hydration products is typical for samples containing SAP. The introduction of SAP into the composition of cement paste leads to the formation of closed pores filled, depending on storage conditions, with water or air, and a decrease in  mechanical properties (by 10-20%). A technological line for the production of UHPC based on polymineral binders using SAP has been developed, it consists of three main stages - the preparation of the polymineral binder, UHPC with desired properties and the manufacture of products from it. 10.34910/MCE.121.8 691 superabsorbent polymer ultra-high performance concrete polymineral binder utilization of industrial waste fly ash structure formation https://engstroy.spbstu.ru/article/2023.121.8/

RAR RUS 12109-12109 57191249816 0000-0002-8080-9808 Ogarev Mordovia State University Rodin Alexander al_rodin@mail.ru https://orcid.org/0000-0002-2560-0948 Ogarev Mordovia State University Ermakov Anatolij anatoly.ermakov97@mail.ru

Saransk, Respublika Mordoviya, Russia

7801669853 0000-0002-3413-247X National Research Mordovia State University Kyashkin Vladimir kyashkin@mail.ru

Saransk, Republic of Mordovia, Russia

0000-0002-4709-4847 National Research Mordovia State University Rodina Natalya rodina.ng@list.ru

Saransk, Republic of Mordovia, Russia

56662851300 0000-0001-8407-8144 Ogarev Mordovia State University Erofeev Vladimir al_rodin@mail.ru Processes of foaming and formation of the structure of porous glass ceramics from siliceous rocks Porous glass-ceramic materials are used in the construction and repair of industrial and civil facilities. They are produced from rocks and industrial waste. The article establishes the influence of the chemical and mineralogical composition of the charge for the production of porous glass ceramics from siliceous (zeolite-containing) rocks and corrective additives (Mg(OH)2, MgCO3, Al2O3) on the processes occurring during its heating. The charge was obtained by joint grinding in a planetary ball mill of siliceous rocks, soda ash and corrective additives. The influence of the charge composition on the processes occurring during its heating has been established by methods of thermal analysis (TA), X-ray phase analysis (XRD), etc. Calcite in the composition of siliceous rocks has a significant effect on the foaming process of the charge. The temperature range of foaming is reduced, and the intensity increases. The additives used have a greater influence on the crystallization process of glass ceramics. As a result, anorthoclase, wollastonite, wollastonite-combeite and diopside glass ceramics were developed. Samples of porous glass ceramics have an apparent density from 154.6 kg/m3 to 298.4 kg/m3, compressive strength from 0.84 MPa to 3.31 MPa, bending strength from 0.57 MPa to 1.52 MPa, maximum operating temperature from 840 °C to 870 °C. According to many physico-mechanical and thermophysical properties, the materials obtained are superior to foam glass and other analogues. They can be used as a thermal insulation material in civil and industrial construction. 10.34910/MCE.121.9 681.7.035:552.55 glass ceramic construction material siliceous rocks processes foaming thermal analysis X-ray phase analysis physical properties https://engstroy.spbstu.ru/article/2023.121.9/

RAR RUS 12110-12110 23493671500 Siberian Transport University Shakhov Sergey sashakhov@mail.ru Structural and phase features of ceramics from loam and incinerated sewage sludge ash The relevance of the work is due to the need to expand the raw material base of the construction industry and develop an effective technology for the disposal of waste from water treatment plants. The purpose of the work was to establish the features of the phase composition and structure of loam ceramics and incinerated sewage sludge ash. The work used differential thermal and X-ray phase analysis, electron microscopy. It has been established that the enrichment of loam by the addition of ash from the incineration of domestic sewage sludge (DSS) ensures the connection of aggregates and individual particles into a single system reinforced with anorthite crystals. In this case, an increase in the amount of the anorthite phase and the mechanical strength of ceramics occurs with an increase in the proportion of ash from the incineration of DSS in the charge to more than 20 %. It is shown that the structure of ceramics made from loam with the addition of ash from the combustion of DSS is characterized by a spatial frame, which is a kind of a matrix that combines filler particles according to the "core-shell" type, and an increase in the number of reserve pores, which favorably affects the frost resistance of ceramics. 10.34910/MCE.121.10 691.42+666.3-1 building ceramics loam incinerated domestic sewage sludge ash phase composition anorthite structure frost resistance https://engstroy.spbstu.ru/article/2023.121.10/