AlfaBuild

RAR RUS 3801-3801 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

Model of a spatial cantilever truss and formulas for calculating its deformations The object of research is a spatial lattice statically determinate regular cantilever truss formed by connecting eight plane trusses. The truss is loaded at its nodes. The longitudinal stiffness of the bars is assumed to be equal. Formulas are derived for the dependence of the truss end deflection on its dimensions and the number of panels. Method. The forces in the bars are found in analytical form using computer mathematics methods by solving a system of algebraic equations. The Maxwell - Mohr formula is used. Generalization of the solutions to the case of an arbitrary number of panels is performed by induction. Results. The resulting formulas for the deflections have the form of polynomials in the number of panels. Formulas are derived for the forces in individual, most critical bars. Asymptotic forms of the solutions are found. 10.57728/ALF.38.1 69 Space truss Maxwell-Mohr formula Induction Maple Analytical solution Deflection Asymptotics https://alfabuild.spbstu.ru/article/2026.38.1/ 3801.pdf

RAR RUS 3802-3802 Peter the Great St. Petersburg Polytechnic University Zimin Sergey Sergeevich zimin_sergei@mail.ru

St. Petersburg, Russia

Orlovich Roman Boleslavovich Dimitrieva Sofia Olegovna Zimina Elena Andreevna Influence of backfilling of masonry vault grooves on their load-bearing capacity In static calculations of stone vaults, backfill is usually considered only as a gravitational load, and its actual interaction with the vault structure is often not accounted for. The object of research is the stress state of stone vaults. The influence of backfill on the load-bearing capacity of stone vaults is analysed. Methods. A numerical analysis was conducted using the finite element method for vaults with a span of 8.0 m and a thickness of 0.25 m. Two backfill materials were considered: sand (E = 120 MPa, density 1500 kg/m³) and expanded clay (E = 15 MPa, density 250 kg/m³). The ratio of vault height to span, f/L, varied from 0.1 to 0.5. Two calculation schemes were compared: one that accounts for the interaction of the vault with the backfill and one that does not. Results. Including backfill in the design model reduces tensile stresses in the vault. The positive effect increases with the vault height-to-span ratio and is more pronounced for cylindrical vaults than for cross vaults. Sand backfill provides a more significant reduction in stresses due to its higher stiffness, but it also increases the overall load on the vault. The share of the horizontal spacer load H, perceived by the backfill, reaches 43% for sand and 37% for expanded clay in semicircular vaults (f/L = 0.5). To reduce the static load, it is recommended to use lightweight backfill materials (such as expanded clay), while maintaining a positive interaction with the vault. The effectiveness of lightweight backfill can be improved by using layer-by-layer consolidation with cement mortar or polymer composite reinforcement. 10.57728/ALF.38.2 69 Cylindrical vaults Cross vaults Filling of vault cavities Stressed state of vaults Masonry structures Vaulted https://alfabuild.spbstu.ru/article/2026.38.2/ 3802.pdf

RAR RUS 3803-3803 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

The first natural frequency and deflection of a two-hinged truss arch The object of research is a statically determinate model of a planar, regular, arched truss on two fixed, hinged supports. Using the induction method in a computer mathematics system, calculation formulas for the structure's deflection under a uniform vertical nodal load on the lower or upper chord are derived. An approximate analytical dependence of the truss's first natural frequency of oscillation on the number of panels is found. The forces in the rods are calculated for an arbitrary number of panels. Method. The truss's inertial properties are modeled using concentrated masses at the nodes. The truss's natural frequency of oscillation is calculated using the Dunkerley method and its simplified version. Vertical node oscillations are assumed. Results. A comparison of the analytical calculations with numerical results, performed taking into account all degrees of freedom of vertical mass oscillations, shows good agreement between the methods. 10.57728/ALF.38.3 69 Arched truss Fundamental frequency Induction Deflection Maple Dunkerley method https://alfabuild.spbstu.ru/article/2026.38.3/ 3803.pdf

REV RUS 3804-3804 0009-0006-9047-9386 Khraponova Liudmila Vladimirovna Brackets for ventilated façades: Material-structural parameters, mechanical-thermal characteristics, and operational reliability. A review The object of research is bracket systems in ventilated façade assemblies, which serve as critical load-bearing and thermal-transfer elements that directly govern the energy performance and service life of building envelopes. Method. A systematic review and synthesis of experimental, numerical, and bibliometric data from recent publications quantified dependencies between material selection, geometric configuration, mechanical performance, and thermal behaviour under static, dynamic, and climatic loads. Results. The analysis establishes quantified relationships between bracket parameters and façade performance. Steel and aluminium brackets provide high load-bearing capacity (60–140 kg/point) but generate significant point thermal bridges . Hybrid aluminium-polyamide and FRP systems reduce , decreasing annual building heat losses by 8-12%. Geometric optimisation, including console shortening and perforation, increases thermal resistance by 8-40%, while doubling the mounting spacing cuts thermal losses by 18% but requires compensatory anchoring reinforcement because stress increases by 25%. Long-term exposure to 5,000 cyclic loads reduces secant stiffness by 10-15%, and combined UV-moisture degradation diminishes polyamide insert strength by 15-20% over a decade. FEM-based topology optimisation reduces bracket mass by 25-30% without compromising structural integrity. Critical gaps in standardised testing for hybrid fatigue, fire safety, and long-term polymer durability are identified, providing a scientific basis for next-generation, digitally optimised, and energy-efficient façade fastening systems. 10.57728/ALF.38.4 69 Ventilated façade systems Brackets Thermal bridges Load-bearing capacity Hybrid composite materials Thermally broken connectors Energy efficiency of building envelopes https://alfabuild.spbstu.ru/article/2026.38.4/ 3804.pdf

RAR RUS 3805-3805 Mawlood Dara Anwer Koyankin Alexander Alexandrovich Mechanical properties of a semi-precast slab with a layered implementation The object of research is a precast reinforced concrete slab, for which an advanced layered finite element method is implemented to model and determine the stress-strain relationships of the constituent materials within the computational framework for semi-precast slabs. This work evaluates the flexural performance of semi-precast slabs through a numerical investigation based on a generalized computational algorithm implemented in MATLAB. The proposed method introduces a layered finite element method for analyzing precast reinforced concrete (RC) slabs, built on a refined global-local plate theory. The cross-section of a semi-precast RC slab is divided into several concrete and steel layers, with each layer treated as an independent plate structure that retains its own material properties. Results. From the input data, the code calculates both global and local stresses and strains. The MATLAB flowchart is provided. A major advantage is that it requires no shear correction coefficients. In addition, although the model is layer-based, the number of unknowns for the displacement and stress fields remains constant, regardless of the total number of layers. Benchmark comparisons and numerical tests show that the proposed method yields highly accurate results while remaining computationally feasible. 10.57728/ALF.38.5 69 Kinematic layer Strain and stress fields Layered formulation Finite element discretization Semi-precast slab https://alfabuild.spbstu.ru/article/2026.38.5/ 3805.pdf

REV RUS 3806-3806 Lotkov Ivan Anatolyevich Life-cycle cost of ductile iron pipelines in water-supply systems: A critical review and an author-developed calculation method The object of research is the economic assessment of buried ductile iron pipelines and technically comparable water-supply pipe materials. Method. A critical synthesis was performed using 112 scientific publications published between 1979 and 2026 and indexed or retrieved through Scopus, Web of Science Core Collection, ScienceDirect, SpringerLink, ASCE Library, IWA Publishing, PubMed, Google Scholar, and eLibrary. Standards were assessed separately. The review compared the objects, data, failure definitions, cost boundaries, time horizons, uncertainty models, validation procedures, and transferability limits of the selected studies. A title-term co-occurrence network was used to reveal the thematic structure of the evidence base. Results. Economic research evolved from deterministic replacement rules based on average break rates to probabilistic life-cycle models that include inspections, imperfect repair, budget constraints, infrastructure interdependence, and service-interruption consequences. Failure-prediction studies provide essential inputs for economic analysis, but their coefficients remain utility-specific because event definitions, censoring, replacement records, climate, soil, and maintenance practices differ among networks. Ductile-iron studies confirm the importance of socket joints, corrosion-protection systems, soil exposure, external loading, and localized corrosion; however, they do not support a universal service-life coefficient or an unconditional economic advantage over polyethylene and steel. Direct comparisons under a common hydraulic function, route, price basis, and analysis horizon remain scarce. Based on the critical synthesis, the author-developed calculation method is formulated. It includes a common functional unit, a risk-adjusted life-cycle cost, threshold values for failure consequences and failure-rate reduction, scenario robustness, minimax regret, and the value of inspection. The method does not predetermine the preferred material and requires local numerical validation. ***ARTICLE IN PRESS*** 10.57728/ALF.38.6 69 Ductile iron pipe Water distribution pipeline Life-cycle cost Failure prediction Corrosion Network renewal Pipe material selection Risk-adjusted cost https://alfabuild.spbstu.ru/article/2026.38.6/

REV RUS 3807-3807 Kalashnikov, Bogdan Dmitrievich Watertight freeze-thaw resistant reinforced concrete members: A review This review addresses watertight reinforced-concrete members exposed to repeated freeze-thaw cycles. The core evidence window covers publications from 2020 to 9 September 2026; earlier studies are retained when they define frost-damage mechanisms or methods for characterizing pore and air-void systems. One hundred peer-reviewed scientific publications were analyzed, while standards were considered separately. Hydraulic-pressure theory, critical saturation, osmotic effects, and salt-related mechanisms were compared against their conditions of applicability, and the evidence was then traced from water ingress and saturation to microdamage, cracking, reinforcement-bond degradation, and member-level response. Studies measuring permeability and freeze-thaw resistance on the same mixtures do exist; the research gap lies instead in inconsistent test procedures and the limited transfer of material indices to reinforced members. In one panel-concrete study, 2% cementitious capillary crystalline waterproofing produced the strongest response and larger dosage weakened the effect; this value is not treated as a universal dosage. Likewise, a favorable result at 0.6% superabsorbent polymer is restricted to the recycled-concrete mixture in which it was measured. At member scale, one RC-beam program after 300 cycles reported an approximately 20% reduction in energy absorption for low-air concrete versus about 7% for concretes with more developed air systems. Heterogeneous mixtures, saturation histories, and test procedures prevent derivation of a universal conversion from concrete test grade to structural service life. The review therefore identifies the applicability limits of existing mechanisms and the data that need to be connected in matched material-to-member test programs. ***ARTICLE IN PRESS*** 10.57728/ALF.38.7 69 Reinforced concrete members Water tightness Frost resistance Freeze-thaw Saturation Air-void system Reinforcement bond Durability https://alfabuild.spbstu.ru/article/2026.38.7/

REV RUS 3808-3808 Lotkov Ivan Anatolyevich Regional applicability of ductile iron pipelines in water-supply systems: A review of climatic, geotechnical, seismic, and operational factors Object of research. Ductile iron pipelines used in water-supply systems under differing climatic, geotechnical, seismic, and operational conditions in the Russian Federation. Objective. To systematize the regional factors governing the performance of ductile iron pipelines and to develop a reproducible framework for selecting their design configuration. Method. A critical review was performed using 121 scientific publications published between 1979 and 2026; standards and information on ten Russian projects implemented in 2020-2026 were assessed separately. For each study, the pipe material, unit of observation, exposure factor, damage mechanism, joint type, protection system, failure definition, and transferability limitations were recorded. Results. Regional applicability cannot be assessed from the wall material separately from the joints, external coating, internal lining, bedding, and operating regime. Seasonal ground movement and pipeline bending govern cold-climate applications; axial and angular joint deformation capacity governs seismic applications; external-protection integrity and backfill quality govern corrosive-soil applications; traffic loading, stray current, constrained repair access, and the cost of service interruption govern large-city applications; and cement-mortar lining condition and microbiological processes govern systems exposed to unstable water chemistry. The Russian project sample shows that ductile iron is primarily selected for transmission and urban water mains, while the joint type and protective configuration vary with topography, soil conditions, and installation method. Conclusions. An author-developed preliminary regional assessment framework is proposed, combining mandatory exclusion criteria, weighted factor scoring, and scenario-based robustness testing. The method does not assign a predetermined advantage to ductile iron over polyethylene, steel, or composite materials and requires calibration using local failure and cost data. ***ARTICLE IN PRESS*** 10.57728/ALF.38.8 69 Ductile iron pipe Water-supply pipeline Regional conditions Frost heave Corrosion Seismic effects Socket joints Pipe material selection Reliability https://alfabuild.spbstu.ru/article/2026.38.8/

RAR RUS 3809-3809 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

0009-0005-5209-7566 Gribova Olga Valerievna Formulas for calculating the deflection of a spatial cantilever truss The object of research is the frequencies of natural oscillations of a regular spacer flat lattice truss. The mass of the truss is conventionally located at its nodes. Only small vertical oscillations of the masses are considered. The rods of the structure are assumed to be linearly elastic. Method. The modified Dunkerley method is used to derive the formula for the dependence of the first natural frequency of the truss free oscillations. For the second frequency, the form of dependence on the number of panels is taken from the solution of the problem of the first frequency, with correction factors that are calculated from the numerical solution by the collocation method at three points. Results. For the first two frequencies of truss oscillations, compact calculation formulas for the dependence on the number of panels are obtained, allowing one to estimate oscillations of a truss with an arbitrary number of panels without loss of accuracy. For an odd number of panels in half a span, the kinematic variability of the structure was discovered and confirmed by the distribution of velocities. 10.57728/ALF.38.9 69 Lattice truss Natural oscillation frequency Induction Maple Analytical solution Second frequency of oscillations Dunkerley method https://alfabuild.spbstu.ru/article/2026.38.9/ 3809.pdf

RAR RUS 3810-3810 Gusev Konstantin Vladimirovich 57194431559 0000-0003-4992-2084 Peter the Great St. Petersburg Polytechnic University Galyamichev Alexander Viktorovich galyamichev@yandex.ru

St. Petersburg, Russian Federation

Abdulova Dalia Ilfatovna Golubkov Nikita Aleksandrovich AAE-3259-2020 56296687300 0000-0002-2299-3096 Rybakov Vladimir Alexandrovich Boundary conditions for adhesive joints in façade cladding elements The object of research is adhesive fastenings in façade metal cassettes of hinged façade systems. This work aims to develop a simplified method for defining boundary conditions of adhesive fastenings of façade cassettes in numerical models. Method. Experimental tests of adhesive tapes were carried out to determine the estimated elastic modulus, load‑bearing capacity, and failure mode. Finite element analysis of façade metal cassettes was performed using different approaches to modelling adhesive joints to assess their influence on the structure's stress–strain state. Results. A preliminary value of the elastic modulus of the structural adhesive tape (375 kPa) and the average failure stress (548 kPa) were obtained. Failure exhibits a mixed adhesive–cohesive character and depends on the loading rate. Replacing silicone sealant adhesive with structural tapes has almost no influence on cassette deflections (2–4%). Numerical models showed that adhesive fastening can be represented as hinged contacts without explicitly modelling solid geometry. Load-width participation factors were determined for various span configurations, and a formula was proposed to calculate stresses in adhesive joints under wind loading. 10.57728/ALF.38.10 69 Adhesive tapes Bonded connections Façade metal cassettes Silicone adhesive sealant Stress–strain state Forces in fastening elements Wind load https://alfabuild.spbstu.ru/article/2026.38.10/ 3810.pdf

REV RUS 3811-3811 Velikii Iaroslav Andreevich 56227381900 0000-0003-2673-4566 Peter the Great St. Petersburg Polytechnic University Nemova (Sergeeva) Darya Viktorovna nemova_dv@spbstu.ru

St. Petersburg, Russian Federation

Auxetic cementitious composites in construction. A review The object of the study is auxetic cementitious composites (ACC), considered with respect to their structural features, testing methods, and applicability in construction. This work aims to classify and analyse existing testing methods for ACC, evaluate their mechanical and thermophysical characteristics compared with conventional cementitious materials, and assess their potential applications in construction practice. Method. This study uses a general scientific method of information synthesis and analysis. Results. The results systematically analyse ACC test methods and their application in construction, including compression and energy absorption, bending, shear, cyclic and dynamic loading, thermophysical, explosion, and impact tests. The analysis indicates that ACC exhibits higher compressive ductility, energy absorption capacity, and resistance to cyclic and dynamic loading than conventional cementitious materials, and that their application options range from protective panels to damping and facade elements. At the same time, sensitivity to geometric deviations during production, specific lattice degradation mechanisms, and the lack of standardised test procedures limit the technology's practical implementation in the construction industry. 10.57728/ALF.38.11 69 Auxetic Cementitious Composites Metamaterials Negative Poisson’s ratio Mechanical behaviour Auxetic Protective structures https://alfabuild.spbstu.ru/article/2026.38.11/ 3811.pdf

REV RUS 3812-3812 Velikii Iaroslav Andreevich 56227381900 0000-0003-2673-4566 Peter the Great St. Petersburg Polytechnic University Nemova (Sergeeva) Darya Viktorovna nemova_dv@spbstu.ru

St. Petersburg, Russian Federation

A systematic testing procedure of auxetic cementitious composites for modular and reinforced construction. A review The object of the research is the method for improving the mechanical characteristics of auxetic cementitious composites (ACC). ACC offer higher strength and greater resistance to deformation and cracking compared with conventional construction materials. This work aims to analyze existing improvement methods, evaluate their limitations, and propose a method for enhancing ACC that accounts for the joint contribution of the lattice and the matrix. Method. A systematic literature review with content analysis was employed, incorporating gap analysis of existing improvement workflows and within-study comparative ranking of experimental results across 20 peer-reviewed publications. Results. This study examines methods for improving auxetic structures and cement paste. 20 research papers were analyzed to assess the influence of the type of auxetic lattice structure, the material used to print the lattice, and the lattice geometry on the physical and mechanical properties of ACC. The study proposed a method to enhance the physical and mechanical properties of auxetic cementitious composites. Experimental analysis showed that reentrant and peanut-shaped structures perform better in compressive and tensile strength, while the octet structure stands out for its high energy absorption capacity. The developed research and improved workflow include selecting target properties, numerical simulation, selecting an improvement method, and conducting experiments. Progress in ACC research remains limited by inappropriate control-specimen selection, too few replicate tests (typically three per series), and fragmented data on geometric effects; standardizing test protocols and increasing replicate specimens to five–ten per series is recommended to improve result reliability. 10.57728/ALF.38.12 69 Auxetic Metamaterials Auxetic cementitious composite Auxetic optimization Method of optimization Metamaterials optimization Modular construction Modular buildings https://alfabuild.spbstu.ru/article/2026.38.12/ 3812.pdf

REV RUS 3813-3813 Saburov Daniil Aleksandrovich 56091980300 Peter the Great St.Petersburg Polytechnic University Lalin Vladimir Vladimirovich vllalin@yandex.ru

St.Petersburg, Russian Federation

AAE-3259-2020 56296687300 0000-0002-2299-3096 Rybakov Vladimir Alexandrovich Buckling of trapezoidal steel deck wall with local load on the support: A review This review article evaluates the existing literature on the calculation and strength of thin-walled elements or steel deck. It is noted that among the publications, there are no works that would consider the dependencies between the parameters of the deck and its strength under local load. Methodology. This article examines a number of open-source studies on the calculation of thin-walled elements using various methods: normative, analytical, and numerical. The influence of the width of the deck support, the thickness of the flooring wall, and the angle of inclination of the deck wall on the bearing capacity of its wall under local load is considered. The study is based on the method of partial coefficients and the direct method, as well as the numerical calculation of the section of the profiled flooring in the ANSYS software package. Results and Discussion. A review of the sources showed that various methods for calculating thin-walled elements have their advantages and disadvantages. Calculations have shown that the thickness has the greatest effect on the stability of the flooring wall. As the thickness of the wall increased, the force of loss of stability increased from 201 to 559.7%, depending on the technique. Conclusion. All the calculation methods used give similar dependencies of the strength of the deck wall on its parameters. The numerical calculation showed that the load‑bearing capacity is 1.07 to 2.25 times greater compared to other methods. This must be taken into account in the numerical calculations of steel deck. ***ARTICLE IN PRESS*** 10.57728/ALF.38.13 69 Steel deck Local buckling Multi-span beam Thin-walled structures https://alfabuild.spbstu.ru/article/2026.38.13/