33407 2304-6295 1 115 2025 1-60

RAR RUS 11501-11501 G-1611-2018 56352359500 0000-0002-5156-7352 Volgograd State Technical University Korniyenko Sergey Valeryevich svkorn2009@yandex.ru

Volgograd, Russian Federation

0009-0004-3019-4309 Tkachev Makar Sergeevich makar.tkachev@mail.ru 0009-0008-8022-6232 Tkachev Sergei Andreevich tsaexp@gmail.com Impact of vegetation layer on external heat transfer characteristics The object of research is a natural physical model of a green roof, which is a fragment of the surface layer of soil with landscaping in the form of a grassy layer on top of the substrate. The climate type is Dfa according to the Köppen classification. Method. Field thermal tests of the object were carried out by the "additional wall" method in the transition (autumn) period of the year. All control tests were performed within 5 days, recording parameters every 5 minutes. The equipment provides high measurement accuracy: for heat flow is plus minus 6%, for temperature is plus minus 0.2%. The measurement process was under control. Results. It has been experimentally established that fluctuations in heat flux and temperature on the surface with the plant layer are complex, due to daily cycles. It has been proven that the plant layer noticeably smoothes the temperature wave formed due to external air temperature fluctuations. The coefficient of smoothing of temperature fluctuations is 2.5–3.0; therefore, the surface layer of the substrate and the vegetable layer are in the zone of active fluctuations. It was experimentally confirmed that the air temperatures at different measurement points almost coincide, which excludes the influence of other factors on the temperature regime of the studied fragment. For the first time, the value of the external heat transfer coefficient (from external surface to external air) for green surface is 14.6 W/(sq.mxK) was established. The external heat transfer resistance for green surface exceeds the standard value by 1.7 times. This can be explained by the fact that vegetation creates additional resistance to convective heat transfer compared to surfaces without landscaping. The obtained results make it possible to more accurately calculate the external heat transfer of landscaped roofs. 10.4123/CUBS.115.1 69 Green construction Green roof Plant layer Substrate External heat transfer coefficient (EHTC) External heat transfer resistance (EHTR) Heat flux density (HFD) https://unistroy.spbstu.ru/article/2025.115.1/ 11501.pdf

RAR RUS 11502-11502 P-3728-2017 57194112309 0000-0001-6184-2365 Vyatka State University Tyukalov Yury Yakovlevich yutvgu@mail.ru

Kirov, Russian Federation

GMW-6276-2022 0000-0002-3884-874X Vyatka State University Ashikhmin Stanislav Eduardovich ashihminstanislav@gmail.com

Kirov, Russian Federation

Adhesion force between composite rods and concrete: The experimental research The object of research is the connection of the composite rods glued into concrete. This work aims to determine the bond strength of the bar to be concrete based on a series of pull-out tests of bonded composite bars. The average shear stresses of the bar to concrete bond at the maximum pull-out force are needed to determine the required anchorage length of the composite rods. Method. Two series of pull-out tests were performed on composite rods glued into a concrete cube with epoxy glue. The series differed in the thickness of the adhesive layer: 7 mm and 3.5 mm. To determine the class of concrete, three samples were tested for compression. Finite element modeling of the pulling of out of a composite rod from a concrete cube was performed and the numerical results were compared with experimental data. Results. Based on the test results, for each series, the average value of the maximum shear stress acting between the rod and concrete was calculated. The values of the stresses were determined by a confidence level of 0.95. Pull-out tests were performed on composite rods cemented into a concrete cube. Experiments showed that in this case the pull-out force and average shear stress increased by approximately 20-25 percent. 10.4123/CUBS.115.2 69 Composite rod Concrete Epoxy adhesion Experiment study Pull-out test https://unistroy.spbstu.ru/article/2025.115.2/ 11502.pdf

RAR RUS 11503-11503 0009-0005-3149-7341 Sorokin Vladislav Vitalievich 0000-0002-3561-8156 Konyushkov Vladimir Viktorovich 0009-0003-0986-2694 Sebkhaoui Ahmed Amine 0000-0003-4894-9023 Perminov Nikolai Alexeyevich Mechanical safety of buildings and structures during underground construction of linear objects in complex geotechnical conditions The object of the research is an existing brick building under which a sloped metro tunnel is being constructed. Method. The influence of tunnel boring machine (TBM) excavation on the stress-strain state of the building's structural elements was investigated using numerical finite element modeling. The construction site is composed of weak, water-saturated soils. The problem was solved in a three-dimensional formulation. Results. The values of additional foundation settlements and stresses in the building structures were determined. The obtained settlement values were compared with field data from geodetic monitoring. Zones of maximum tensile stresses in the masonry were identified. Based on the building's technical survey data, the most vulnerable defective floor structure was selected. Based on the probabilistic method for assessing the structural safety of buildings, the limit values of forces for the most defective structure were determined, which are used to assign the type of technical condition of the building under consideration. 10.4123/CUBS.115.3 69 Buildings and structures Underground construction Safety Dense buildings Shield tunneling Stress-strain behavior Tunnels Finite element method https://unistroy.spbstu.ru/article/2025.115.3/ 11503.pdf

RAR RUS 11504-11504 57208104857 0000-0003-3313-7305 Kazan State University of Architecture and Engineering Zamaliev Farit Sakhapovich zamaliev49@mail.ru

Kazan, Russian Federation

0000-0003-0569-4788 Tamrazyan Ashot Georgievich O-6995-2019 6508103761 0000-0002-1196-8004 Peter the Great St. Petersburg Polytechnic University Vatin Nikolai Ivanovich vatin@mail.ru

St. Petersburg, Russian Federation

Anchor bonds of the contact joint of steel-concrete structures The object of the research is anchor ties of composite steel-concrete structures. Based on experimental studies, new dependencies reflecting the actual stress-strain state of the contact of composite bending elements are recorded. The smallest discrepancies between analytical and experimental results are shown. Method. The existing methods for calculating the contact of composite rods are analyzed, new dependencies of the contact work are recorded, reflecting the actual work of the ties on bending and tension. For experimental verification, models of samples operating on shear are made. The samples are pasted over with strain gauges and devices recording the shear of the layers. Results. Numerous tests have shown that at the "concrete-steel" contact of a composite steel-concrete section, curvilinear stresses arise in concrete, and the anchor rod works on bending with tension. New dependencies reflecting the work of concrete and anchor of the contact of layers are recorded. Comparisons of the results of analytical calculations with experimental data show that the discrepancies do not exceed 5%. 10.4123/CUBS.115.4 69 Steel-reinforced concrete structures Anchor connections Anchor strength Analytical dependencies https://unistroy.spbstu.ru/article/2025.115.4/ 11504.pdf

RAR RUS 11505-11505 H-9967-2013 16412815600 0000-0002-8588-3871 National Research University Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

Gribova Olga Valerievna Formula for the lattice truss fundamental frequency vibration The research object is a statically determinate planar lattice truss with an arbitrary number of panels. The design with two hinged supports allows kinematic variability for some numbers of panels regardless of the acting load. Method. As applied to a structure with an admissible number of panels, the analytical expression for the first frequency of free vibrations is derived using a simplified version of the approximate Dunkerley method. Comparison of the analytical solution with the numerical one shows its high accuracy, which increases with the number of panels. Analytical transformations were performed in the Maple computer mathematics system. Results. The formula for calculating the oscillation frequency has the form of a polynomial in the number of panels and can be used for simple evaluation of solutions obtained numerically. The algorithm for deriving the frequency formula can be used in similar problems of structural mechanics. 10.4123/CUBS.115.5 69 Truss Computer Mathematics System Natural frequency Simplified Dunkerley method Analytical solution Spectrum https://unistroy.spbstu.ru/article/2025.115.5/ 11505.pdf

RAR RUS 11506-11506 0009-0004-0605-8980 Hassan Muhammad Khizar 0009-0002-1894-7967 Siddiqui Aiman 0009-0001-7494-9070 Ahmed Rana Rabnawaz 0009-0000-9466-8973 Ahmed Anas 0009-0001-8953-0221 Tanoli Muhammad Ashraf 0000-0002-9758-6997 Ali Rashid Mechanical and microstructural characterization of recycled plastic waste in sustainable building applications The object of research is Acrylonitrile Butadiene Styrene (ABS) plastic waste, amalgamated with sand, as a viable alternative for constructing plastic-sand composite blocks. Method. The research employs a systematic approach to determine the optimal ratio of plastic to sand, ultimately establishing a 1:1 ratio that optimizes the compressive strength. Results. Experimental results revealed that the developed plastic-sand composite blocks achieved a maximum average compressive strength of 15 MPa, significantly surpassing the minimum requirement of 5 MPa outlined in the IS 2185-2005 (Part 1) code for solid concrete blocks. Comprehensive testing, including comparative analyses of compressive strength and water absorption, demonstrated the superior mechanical properties of the plastic-sand composite blocks compared to conventional concrete blocks. Additionally, thermal, hardness, soundness, and density assessments confirmed adherence to relevant standards. Microstructural examinations using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) tests revealed a compact microstructure with reduced porosity, indicating enhanced strength and durability. The XRD analysis further confirmed the presence of silica in the composite, supporting its structural integrity. These findings underscore the feasibility of utilizing plastic waste in environmentally friendly construction applications, promoting sustainable building practices. 10.4123/CUBS.115.6 69 Plastic Waste Waste Management Sustainable Construction Material Characterization Microscopic Analysis Environmental Impact Circular Economy https://unistroy.spbstu.ru/article/2025.115.6/ 11506.pdf