Magazine of Civil Engineering

RAR RUS 12201-12201 Volgograd State Technical University Golikov Alexander alexandr_golikov@mail.ru

28, Lenina Ave., Volgograd, Russia, 400005

56437725200 0000-0002-6687-7249 Moscow State University of Civil Engineering (National Research University) Garanzha Igor garigo@mail.ru

Moscow, Russia

Volgograd State Technical University Cherkasova Ksenya cherkasova.ksenya@yandex.ru

Volgograd, Russian Federation

Stress-strain conditions of steel rod structures nodes To obtain qualitative and quantitative indicators of changes in the stress-strain state of the nodes of steel bar structures, we identified four characteristic types of nodes. On the basis of modeling in the "Lira-CAD" software package, we analyzed the stress-strain state of four types of nodes for steel trusses with a symmetric and asymmetric design solution. For the research, a calculation of volumetric models of nodes according to the fourth strength theory was performed. At the current moment, the choice of the required thickness of the truss gusset is performed according to the value of the maximum force in the rods. During the nodes modeling it was found that the safety factors depending on the node type for the symmetrical design solution are more than 40 %. The obtained data allow us to reduce the thickness of the gusset taking into account design constraints. It was found that the safety factors depending on the node type for the asymmetric design solution are 7–90 %. The simulation results substantiated the possibility of reducing the gusset thickness for node type 3, and for node types 1, 2 and 4, they showed the necessity of increasing the thickness taking into account design constraints. We derived the refined dependences between the gusset thickness and the maximum force in the attached rods for each structural type of nodes. Based on results of the analysis, we developed recommendations for calculating the most typical types of nodes and presented them in the form of tables and dependencies. For a constructive solution of fastening of gusset braces at an acute angle, we analyzed the influence of the eccentricity value on the stress in gussets. We determined that the main parameter influencing to the stress-strain state of the gusset is the displacement of attached element relative to the axis of the elements fastening. We derived dependences and made graphs of the displacement influence on stresses for different values of gusset thickness. 10.34910/MCE.122.1 624.014.2 stress-strain state gusset rod fastening recommended thicknesses safety factor equivalent stress https://engstroy.spbstu.ru/article/2023.122.1/

RAR RUS 12202-12202 Peter the Great Saint Petersburg Polytechnic University Stolyarov Oleg oleg.stolyarov@rambler.ru

Polytechnicheskay, 29

Peter the Great St. Petersburg Polytechnic University Dontsova Anna anne.dontsoova@gmail.com

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

B-6662-2019 57204916380 0000-0002-6877-8420 Peter the Great Saint Petersburg Polytechnic University Kozinetc Galina galina4410@yandex.ru

St. Petersburg, Russia

Structural behavior of concrete arches reinforced with glass textiles Thin-walled concrete structures with textile reinforcement have a number of advantages over conventional reinforced concrete. This article discusses the manufacturing method and investigates the structural behavior of the arch made of textile-reinforced concrete (TRC). The possibility of manufacturing an experimental arched structure with textile reinforcement is demonstrated. This study includes the arch design, mold preparation and loading test. With the use of a 3D printer, the mold of the arched structure was printed, which made it possible to implement a distributed loading scheme. Three concrete arches including a reference non-reinforced arch and two concrete arches reinforced with glass textiles were designed and tested. The test results showed a slight increase in the strength of the reinforced arch compared to the control non-reinforced arch. The effectiveness of the reinforcement of the arch structure amounts to about 10 % increase in contrast to arches with external reinforcement, where the increase in strength reaches 40–85 %. However, the main advantage of such reinforcement is the significant residual strength of the arch structure, which prevents catastrophic collapse of it. The textile reinforcement continued to hold the failed concrete matrix in contrast to the external reinforcement, where the loss of cohesion leading to delamination could cause the fracture of parts of the concrete. 10.34910/MCE.122.2 691.328.43 textile-reinforced concrete arch structures thin-walled structures flexural test strength https://engstroy.spbstu.ru/article/2023.122.2/

RAR RUS 12203-12203 6506988482 Vladimir State University Chukhlanov Vladimir kripton0@mail.ru

Vladimir, Russia

0000-0001-7588-3555 Vladimir State University Smirnova Natalia smirnovann@list.ru

Vladimir, Russian Federation

57554386400 0000-0002-4342-4255 Vladimir State University Krasilnikova Irina krasilnikovaia@list.ru

Vladimir, Russian Federation

Vladimir State University Chukhlanova Natalia natalyferre@yandex.ru

Vladimir, Russian Federation

Heat-conducting and dielectric characteristics of polyorganosiloxane composites The article considers the actual problem of improving the physico-mechanical, thermophysical and electrical properties of polyorganosiloxane coatings. In this article, we propose a method for obtaining a multifunctional heat-resistant composition based on oligodimethylsiloxane with terminal hydroxyl groups filled with boron nitride. The curing process of oligodimethylsiloxane and the possible interaction of boron nitride with reactive resin groups are described. The structure of the manufactured composition is investigated, it is established that the filler in the form of dispersed particles touching throughout the volume is evenly distributed in the polymer matrix. The results of experimental studies of the dependence of the tensile strength on the percentage of boron nitride, indicating the hardening of the composite, are graphically presented. Studies of the strength at separation of the cured composition from the substrate (adhesion) of various materials have shown that this value increases with the introduction of boron nitride. The dependence of the thermal conductivity coefficient on the ratio of components is established. The percolation point is determined by the Monte Carlo method. The dependences of the electrical resistivity and temperature dependence on the content of boron nitride are determined. The Poisson equation is solved in MathCad and graphical results of solving the heat transfer problem for traditional and developed composites are presented. Based on the results obtained, the areas of application of the developed composites in construction are proposed. 10.34910/MCE.122.3 621.315.616.9 polymers oligodimethylsiloxane boron nitride strength adhesion permittivity thermal conductivity https://engstroy.spbstu.ru/article/2023.122.3/

RAR RUS 12204-12204 Vignana Bharathi Institute of Technology Prasad Venkata cvsrprasad90@gmail.com

Hyderabad, India

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

Polytechnicheskay, 29

Vignana Bharathi Institute of Technology Devi Sree sreelakshmidevi159@gmail.com

Hyderabad, India

Department of Civil Engineering, Zakir Husain Engineering College Najm Hadee gk4071@myamu.ac.in

Aligarh, India

Nawroz University Majeed Samadar heerlen1990@gmail.com

Duhok, Iraq

Department of Civil Engineering, College of Engineering, University of Duhok Qaidi Shaker shaker.abdal@uod.ac

Duhok, Iraq

Mechanical and microstructural properties of self-healing concrete based on Hay Bacillus The experimental investigation delves into assessing the influence of varying ratios of calcite (Cc) and sand on the mechanical and microstructural characteristics of self-healing concrete (SHC). This study employs Hay Bacillus as a catalyst for initiating calcite precipitation within the concrete matrix. The proportions of calcite under scrutiny encompass 5%, 10%, and 15% of the cement's weight. Additionally, two distinct types of sand, crushed stone sand (CSS) and river sand (RS) are juxtaposed for comparative analysis. The primary focus of this research is on evaluating the compressive and flexural strengths of the SHC, with particular emphasis on the utilization of a 10% bacterial solution. This proportion emerged as the optimal dosage for enhancing concrete strength. To gain a comprehensive understanding of the underlying mechanisms, the microstructure of the concrete is probed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. These tests allow elucidating the impact of varying calcite and sand ratios on the formation of calcium lactate, as well as the production of calcium silicate hydrate (CSH) gel and non-expanding ettringite within the concrete matrix. This investigation contributes valuable insights into the development of self-healing concrete with improved mechanical properties, underpinned by a deeper comprehension of its microstructural transformations. 10.34910/MCE.122.4 691.3 self-healing concrete hydrostructures Hay Bacillus crushed stone sand river sand calcite microstructural https://engstroy.spbstu.ru/article/2023.122.4/

RAR RUS 12205-12205 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

Validation metrics for non-linear soil models using laboratory and in-situ tests The article discusses the application of statistical metrics for the validation of comprehensive non-linear soil models. The assessment was carried out on the basis of triaxial, oedometer, consolidation and plate load tests of sandy and clay soils. Validation of non-linear soil models was divided depending on the problem type: strength-type problem and strain-type problem. For a strength-type problem the indicators of failure points should be compared. In the course of strain-type problem the stress-strain curves should be compared. Average ratio of experimental data to calculated and coefficient of variation showed the highest efficiency for standard triaxial and oedometer tests, as they allow taking into account the specificity of the deviation and its variability. Other statistical metrics are less effective in geotechnical engineering. Validation according to consolidation tests is recommended to be performed based on the analysis of the time of 100% primary consolidation and the slope of the consolidation curve during the creep phase. In the course of stress paths analysis (for example, in the course of unloading and further reloading), the advantage should be given to visual assessment. Acceptable values of validation metrics for geotechnical engineering are proposed. The specific values of deviations should be determined by the analyst depending on the required accuracy of calculations, the responsibility of the construction object and the assessment of the risk of an accident. 10.34910/MCE.122.5 624.131 numerical modeling verification validation laboratory tests in-situ testing statistical analysis back analysis https://engstroy.spbstu.ru/article/2023.122.5/

RAR RUS 12206-12206 Kazan State University of Architecture and Engineering Rakhimova Nailia rahimova.07@list.ru 55530988100 Kazan (Volga region) Federal University Morozov Vladimir Vladimir.Morozov@kpfu.ru

Kazan, Russian Federation

Kazan (Volga region) Federal University Eskin Alexey eskin.aleksey@gmail.com

Kazan, Russian Federation

Alkali-activated bentonite clay-limestone cements The development of sustainable cements requires the expansion and optimization of the mineral resources base. In this study, the medium-grade bentonite clay and limestone as a promising, available, low carbon, and abundant starting materials, were investigated as binary precursors for eco-friendly non-clinker alkali-activated cements development. Properties of fresh and hardened pastes of blended alkali-activated cements were investigated by standard techniques depending on the mineralogical assemblage, fineness of precursors, formulation details. The reaction products and microstructures of alkali-activated calcined bentonite clay-limestone hardened pastes were analyzed using thermal, XRD, and SEM/EDS analyses. As a result, calcined bentonite clays at 39–47 % content of clay minerals were stated to be suitable as a primary precursor for alkali-activated cements incorporated with high loading of raw limestone. Optimum compositions consisted of 20–30 % calcined clay and 70–80 % limestone with compressive strength up to 34.2 MPa. In the designed cement calcined bentonite clay is the main reactive precursor that forms a mineral matrix sodium aluminosilicate hydrate gel N-A-S-H, whereas calcium carbonate is a much less reactive secondary precursor that participates in the formation of sodium (calcium) aluminosilicate hydrate gel N-(C)-A-S-H. 10.34910/MCE.122.6 691.54 geopolymers mixtures cementitious materials compressive strength microstructure https://engstroy.spbstu.ru/article/2023.122.6/

RAR RUS 12207-12207 57190863290 https://orcid.org/0000-0002-0274-0673 Industrial University of Tyumen Maltseva Tatyana maltsevatv@tyuiu.ru

Tyumen, Russia

Industrial University of Tyumen Bai Vladimir bajvf@tyuiu.ru

Tyumen, Russian Federation

Industrial University of Tyumen Erenchinov Sergey erenchinovsa@tyuiu.ru

Tyumen, Russian Federation

Industrial University of Tyumen Esipov Andrey esipovav@tyuiu.ru

Tyumen, Russian Federation

Industrial University of Tyumen Chumanova Natalya chumanovana@tyuiu.ru

Tyumen, Russian Federation

Bearing capacity of frame-gantry pile foundations The object of the study is frame-gantry pile foundations embedded in the soil base. To improve the strength of weak soil base, various methods of reinforcement are used, including the foundation constructions in the form of wedge-shaped piles. The paper deals with laboratory studies of the soil base during the installation of small-scale wedge-shaped piles at different angle. The process of soil shearing under the influence of the loads is registered by deformation control benchmarks arranged in the form of a square grid. The interaction between the soil and the frame-gantry foundations appears in a change of the physical and mechanical characteristics in the near pile area. The tests revealed that when piles are installed at the angle of 30° the bearing capacity of the foundation increased. The average density in the fixed active zone of the soil area increased by 12 %, and the average porosity coefficient decreased by 20 %. The deformation modulus changed by 1.8–2.3 times. The angle of internal friction remained virtually unchanged. 10.34910/MCE.122.7 624.1 experimental flume clay soil of wedge-shaped piles frame-gantry piles the benchmarks using a special template the deflectometers for measuring settlement bases foundations https://engstroy.spbstu.ru/article/2023.122.7/

RAR RUS 12208-12208 0000-0002-9672-4374 Kazakh National Technical University named after K.I. Satpayev Mukhanbetzhanova Zhanna sh.zhanna@bk.ru

Almaty, Republic of Kazakhstan

Strengthening and restoration of damaged reinforced concrete structures with composite plastics This paper considers directions to devise methods for restoring the operational suitability of reinforced concrete structures. Mistakes of designers and non-compliance with the concreting technology of monolithic reinforced concrete structures lead to the formation of cracks and deflections of unacceptable size in reinforced concrete beams and floor slabs, as well as to insufficient strength of the elements. Such structures require not only an increase in bearing capacity but also the restoration of the operational suitability of damaged structures. A technique for restoring the serviceability of bendable reinforced concrete structures with increased deflections and excessive crack opening is proposed. To restore bendable reinforced concrete structures, surface reinforcement with pre-stressed fiber-reinforced plastics is suggested, which is ensured by the creation of a building lift in the damaged elements. Unlike conventional reinforcement methods, surface reinforcement techniques are characterized by high gain efficiency, corrosion resistance, low labor intensity, and short terms of work; they ensure strength increase and provide for economic feasibility. This study’s results established that the use of fiber-reinforced plastics not only increases the bearing capacity of reinforced concrete structures but also helps reduce the width of the cracks formed. Thus, it is possible to avoid an increase in the cross-section of structures and reduce the time of operations, which could lead to additional costs. 10.34910/MCE.122.8 624.012 stress-strain state gusset rod fastening recommended thicknesses safety factor equivalent stress https://engstroy.spbstu.ru/article/2023.122.8/

RAR RUS 12209-12209 55902853200 0000-0002-8134-5435 University of Hafr Al Batin Yusuf Moruf moruf@uhb.edu.sa

Saudi Arabia

Performance of aluminium shaving waste and silica fume blended mortar This study investigates the impact of aluminium shaving waste (ASW or Ax: 0.0, 1.0, 1.5, 2 wt%) on the silica fume (SF or Sy: 0-10 %) blended ordinary Portland cement (OPC or C88-100%) mortar. The sample was designated as C100-x-ySyAx and the evaluations were done through their performances in terms of workability, compressive strength, thermal residual strength and microstructural characteristics in comparison with the OPC only mortar (C100S0A0). The increase in ASW/SF ratio enhanced the workability of SF blended (C90-xS10Ax). The unit weight of mortar reduced with increase in ASW/SF ratio so that 19.7 % was lost with the incorporation of 2 % of ASW. ASW induced effervescence of hydrogen gas in the fresh sample thereby leading to unit-weight reduction. The inclusion of 1 % ASW in ternary blending gave the optimum performances of 28-day strength (53.8 MPa) and residual thermal (300 °C, 1 h) strength of 56 MPa that had a comparable value to OPC mortar (55 MPa) unexposed to the thermal treatment. ASW also caused thermal stability in SF-ASW blended mortar as addition of 0.5, 1.5 and 2 % ASW caused 33.8, 15.6 and 33.4 % loss in 28-day strengths, respectively, while the least was observed in 1 % ASW sample with the loss of 8.8 %. Finally, ASW enhanced weight reduction (at 300 °C for 1 h) as the unit weight reduced by 1.75, 4.89, 3.30 and 1.86 % in C89.5S10A0.5, C89S10A1, C88.5S10A1.5 and C88S10A2, respectively, in comparison with C100S0A0. Mayenite and muscovite could be formed as products when ASW is used as supplementary materials in silica fume blended mortar production. 10.34910/MCE.122.9 691.5 compressive strength hydration thermal conductivity supplementary cementitious materials silica fume microstructure https://engstroy.spbstu.ru/article/2023.122.9/

RAR RUS 12210-12210 56825170800 0000-0002-9079-2667 South-Ural State University Potapov Alexandr potapov.alni@gmail.com

Chelyabinsk, Russian Federation

0000-0002-7911-2691 Daegu University Shturmin Sergei sturmakmlp@gmail.com

Gyeongsan, Republic of Korea

Accounting of plastic deformations in the calculation of frames using the displacement method Method for calculating statically indeterminate frames taking into account plastic deformations, which is based on the use of a schematized diagram of material with hardening is proposed. Two types of standard beams with supports are used during the implementation of the displacement method (DM) like the elastic solution of the problem: “fixed” - “pinned” and “fixed” – “fixed”, but unlike the elastic solution, standard beams contain special zones that besides elastic part include elasto-plastic zone (EPZ), plastic zone (PZ) and reinforcement zone (RZ). Therefore, as the stresses in these zones did not exceed the yield stress in the nonlinear frame calculation, we took measures to transform the PZs into equal strength plastic zones (ESPZ). The calculations were made for both types of beams for all unit and load impacts. The frame calculation consists of three stages (elastic, elasto-plastic and plastic). At the elastic and elasto-plastic stages, yield moment and plastic moment diagrams and the corresponding loads are determined. For a practical use of the DM in a nonlinear frame calculation, two simplifying prerequisites are introduced, with the help of which a stress-strain state is modeled in two zones: EPZ and PZ. According to the prerequisites, deformation of fibers occurs without hardening in EPZ and with hardening in PZ. The plastic stage of the calculation is performed at a given length of the PZ using the method of sequential loadings. At each iteration with small loading steps, incremental equations for DM are written, which establish relations between incremental moments and the incremental load, which allows us to build a resulting moment diagram. This diagram represents a sum of the moment diagram obtained at the elastic and elasto-plastic stages and the diagrams of incremental moments at all previous loading steps of plastic stage. According to the resulting diagram, the length of the PZ can be calculated, together with the limiting load. The calculation is considered complete if the length of the PZ does not exceed the specified value within the margin of error. Proposed algorithm is illustrated with an example of static calculation of 2-storey steel frame which perceives horizontal load actions that model a seismic impact. 10.34910/MCE.122.10 624.94.014.2:624.044.3 stiffness deformation elastoplasticity nonlinear analysis plastic zone limiting load https://engstroy.spbstu.ru/article/2023.122.10/