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Stress-strain state and stability of hinged-supported constructions along the boundary of shallow reinforced concrete shells

https://doi.org/10.58224/2618-7183-2026-9-1-7
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Abstract
This article examines the performance of shallow reinforced concrete shells with hinged supports along their perimeter. The relevance of this topic stems from the widespread use of such structures in modern construction for covering large buildings, as well as the insufficient understanding of their behavior under non-ideal boundary conditions. The aim of the study is to evaluate the stress-strain state and stability of the shells, taking into account geometric and physical nonlinearity, as well as the effect of long-term loads (concrete creep). The modeling was performed using the finite element method in the Pascal programming language based on DELPHI-7. The calculations take into account the rheological properties of concrete, nonlinear stress-strain relationships, and various loading schemes. Linear and nonlinear stability analyses were performed, including those involving the possible failure of supporting elements. The results showed that, when supported by a hinge, the shell loses stability under loads significantly lower than the design value, especially under long-term loads. The formation of characteristic localized dents and a loss of overall spatial performance of the structure were also detected. These data highlight the need for more accurate consideration of boundary conditions and nonlinear effects in the design of shallow shells. Recommendations are proposed for optimizing the shell shape and reinforcing the contour to improve its stability. The obtained results can be used in engineering practice for the analysis, design, inspection and safety of similar structures.
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Experimental evaluation of the thermophysical performance of an adaptive composite wall system under dynamic climatic conditions

https://doi.org/10.58224/2618-7183-2026-9-1-8
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Abstract
In the sharply continental and hot climate of Kazakhstan, improving building energy efficiency requires adaptive composite envelope systems capable of dynamically responding to external thermal loads. This study provides experimental validation of a newly developed adaptive energy-efficient wall assembly with alternating air channels and a radiant barrier, previously proposed and numerically investigated by the authors. The experiments were conducted in a climatic chamber using a full-scale 3×3 m wall fragment under two operating modes: cold conditions (–14.3 °C) and hot conditions (+26.4 °C with exterior cladding heated up to +46 °C). Interlayer temperatures, heat flux density, and thermal bridging in the bracket zone were measured, and both calculated and effective thermal transmittance resistance values were determined in accordance with regulatory requirements. The experimental results demonstrated strong agreement with numerical simulations: deviations in interlayer temperatures did not exceed 3-7%, while heat flux density differed by 6-9%. The wall configuration Scheme 3/50/75/50 exhibited pronounced adaptive behavior; switching to the ventilation mode during the hot period reduced heat flux density by up to 14% and decreased the temperature gradient within the air channel by an average of 3-5 °C. Under cold conditions, the system increased thermal resistance by up to 18% compared with assemblies without a reflective layer. The obtained effective thermal resistance values comply with the building standards of the Republic of Kazakhstan and confirm the energy efficiency of the wall system for operation in extreme climates. Overall, the experimental validation confirms the reliability of the model and the high practical applicability of the adaptive wall technology. The findings provide a scientifically grounded basis for the development of façade design standards optimized for Central Asian climates and demonstrate the potential for implementation in both new construction and retrofit projects.
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Investigation of the synthesis of a grinding intensifier from secondary raw materials and its influence on the microstructural development of cement stone

https://doi.org/10.58224/2618-7183-2026-9-1-9
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Abstract
This paper presents data on the synthesis of cement grinding intensifiers produced from oil and gas processing wastes, namely secondary alkanolamines. The results of physicochemical characterization of the raw materials are reported, including the optimal purification conditions for the wastes and the synthesis parameters of the grinding intensifiers, as well as the physicochemical properties of the obtained products. It was found that the optimal conditions for producing the grinding intensifier involve conducting the reaction at 45°C for 6 hours with a 1:9 component ratio. The effects of the synthesized intensifiers on the cement clinker grinding process were investigated, including their influence on particle size distribution and the mineralogical composition of modified cements. The particles of the modified cement were shown to exhibit a predominantly spherical morphology; the maximum laser diffraction value reached 13.5%, the intensity was 88%, and the particle size was mainly around 2 μm (more than 53.5%), while the fraction of particles within the 100-200 μm range was 4.87%. X-ray diffraction and differential thermal analysis revealed that hydration of the modified cement is accompanied by a slight decrease in the diffraction intensity of calcium silicate phases (C2S and C3S), whereas an increase in the diffraction intensity of calcium hydroxide (Ca(OH)2) was observed. This indicates the formation of calcium hydroxide and calcium silicate hydrate (C-S-H) during cement hydration. The diffraction peaks of these phases were detected within the ranges of 30-33° 2θ and 40-45° 2θ. In addition, the presence of aluminate (C3A) and ferrite (C4AF) phases within 40-45° 2θ corresponds to calcium carbonate (CaCO3) observed in low-intensity regions between 29.4° 2θ and 48.5° 2θ, which is associated with CO2 absorption from the atmosphere. These changes reflect phase transformations during hydration and the formation of phases that are critical for strength development. The optimal dosage of the grinding intensifier in the cement composition was determined to be 0.02 wt.% (based on dry residue).
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Bulk thermostabilization and surface UV activation as a wood modification method for glued beams in long-span structures

https://doi.org/10.58224/2618-7183-2026-9-1-10
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Abstract
This paper presents an innovative two-stage physicochemical modification approach for softwood species, aimed at enhancing the operational reliability of glued laminated timber beams used in long-span building structures. In the first stage, bulk thermal modification (TM) is carried out in the exhaust gas atmosphere of a waste-heat boiler at 180–240 °C, resulting in reduced hygroscopicity, improved dimensional stability, and enhanced biological resistance. In the second stage, the surface layer of the thermally modified wood undergoes ultraviolet (UV) irradiation (wavelength: 253 nm; dose up to 7.4 kJ/m²) to restore hydrophilicity and improve adhesive bonding performance. Experimental results confirm that the contact angle of the surface decreases from 82° (TM only) to 8° at a UV dose of 7.4 kJ/m² – corresponding to a 90 % increase in wettability. Shear strength of the adhesive joint increases by 22.4 % compared to untreated thermally modified wood and approaches the level observed for joints made from untreated pine wood (deviation < 9 %). After two-stage modification, the mechanical performance of glued laminated beams – specifically, the modulus of rupture in static bending – reaches 58.3 ± 2.1 MPa, fully complying with the requirements of GOST 20850-2014 for glued laminated timber structures of strength class C24 and above. The proposed technology successfully combines the high moisture and biological resistance of thermally modified wood with reliable adhesive bonding-an essential requirement for load-bearing structural elements exposed to cyclic variations in temperature and humidity.
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Research on air purification from pulverized large-tonnage tailings of non-ferrous metal ores and the possibility of their use as secondary raw materials

https://doi.org/10.58224/2618-7183-2025-8-6-1
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Abstract
Pulverized waste (large-tonnage tailings) from the enrichment of non-ferrous metal ores pose a significant environmental threat and a health hazard to the personnel of enterprises and the population of nearby territories. In this regard, this study is devoted to solving the problem of dust suppression with the prospect of subsequent complex tailings processing. The effectiveness of a combined method combining fine-dispersed hydraulic spraying and pulsating ventilation for dust deposition from the tailings of the former Kentau Enrichment Plant (Kentau, Kazakhstan) has been experimentally studied. Laboratory tests were carried out on a specialized stand with monitoring of microclimatic parameters. The results showed that the combined method reduces the dust deposition time by approximately 30% compared to traditional irrigation and by more than two times compared to natural precipitation. Optimal process parameters have been established: nozzle diameter of 10 microns, liquid pressure of 5.4 MPa, air flow velocity of 4 m/s, pulsation frequency of 13 Hz. Based on the X-ray phase analysis of the tailings composition (the total content of zinc compounds is ~3.77%, lead ~4.47%), the economic feasibility of their complex processing is substantiated. A two-stage technology is proposed: preliminary, associated extraction of valuable metals (Zn and Pb) followed by the use of a non-metallized residue rich in oxides of silicon, aluminum and calcium in the production of building materials (cement clinker, ceramics). Thus, effective dust suppression is the first step towards the transition from passive waste storage to active recycling within the framework of the principles of circular economy, which will significantly improve the environmental situation in the region.
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Improving the performance of concrete for bridge structures

https://doi.org/10.58224/2618-7183-2025-8-6-2
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Abstract
Concrete for ambitious engineering projects, including bridges, must meet certain requirements related to strength, water resistance, frost resistance and plasticity. The objective of the article is to improve the efficiency of concrete for bridge structures. The compositions of high-strength building composites have been optimized with a reduction in the proportion of the clinker component. The densest packing of filler particles has been achieved, providing a self-compacting effect during hardening. The compositions of building composites have been optimized at the macro-, micro- and nanolevels to obtain a high-density matrix packing and increase the strength of the composite (including taking into account the granulometric analysis of fillers and the choice of superplasticizer). New properties of high-strength building composites (rheology of highly concentrated dispersed systems, shrinkage deformations, workability, setting time, etc.) have been studied. The results of fresh properties of the developed mixtures showed their compliance with the P5 grade, which indicates that they have good transportability to the place of manufacture of bridge structures. The study of the physical and mechanical characteristics of cement composites (average density, porosity, compressive and bending strength, elastic modulus, frost resistance, shrinkage, Poisson's ratio) showed that the obtained materials can be effectively used for the construction of critical structures, including bridges.
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Improving the operational characteristics of wall ceramic products through the use of coal waste heap processing materials

https://doi.org/10.58224/2618-7183-2025-8-6-3
Abstract
Existing methods for disposing of coal industry waste do not ensure their effective use in the production of building materials, leading to the accumulation of waste dumps and worsening environmental conditions. This research addresses the performance limitations of traditional ceramics by proposing the integration of fine-grained coal mining waste as a primary raw material component. This strategy serves a dual purpose: resolving waste disposal concerns and enhancing ceramic properties through structural modification. The study evaluates the key physicochemical properties of such waste and their effect on material quality. It was determined that the inclusion of fine waste fractions necessitates optimized firing parameters to counteract reductions in density and strength. Empirical models defined the relationship between waste fineness, sintering temperature, and mechanical properties. A specialized semi-dry pressing method was engineered to minimize strength degradation and ensure the production of consistent ceramic blocks. The overarching goal of this technological approach is to achieve cost reduction and heightened product reliability via an optimized synthesis of raw materials and thermal regimes. Application of this method using Eastern Donbass coal waste is envisaged to ensure economic viability while upgrading the technical profile of the resulting construction materials.
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Adhesive bond integration into steel structures of emergency shelters

https://doi.org/10.58224/2618-7183-2025-8-6-4
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Abstract
Natural hazards and resulting technological disasters are currently becoming regular. In these conditions, the creation of emergency shelters is a foremost task of the government to provide the harmed population with housing units in a short time. In the framework of the integration of advanced materials and technologies into steel structures to create safe emergency shelters, experimental research is conducted into adhesively bonded steel-to-steel connections based on epoxy resin laminate. Such connections are interesting for prefabricated modular construction of emergency shelters, as they allow avoiding sectional weakening and stress concentrators common to welding and screw connections. Young’s modulus and shear modulus determined for the epoxy adhesive, are crucial parameters for accurate design. The paper studies the strain distribution in epoxy bonded steel-to-steel connections, identifies strain stages and strain concentration zones, leading to a combined cohesive-adhesive fracture. The obtained results can be used to transfer form empirical building to theoretically substantiated strength analysis of safe and reliable assemblies of prefabricated adhesively bonded steel structures.
The paper presents integrated experimental research into epoxy bonded steel-to-steel connections based on FibArm Resin Laminate+. Tensile strain distribution is identified along the sample longitudinal axis. Four strain stages (elastic, yield plateau, plastic and pre-fracture) are determined together with the evolution of localized elastoplastic strain regions on the surface of the steel plate.
Identified are a nonuniform strain distribution with alternating compressive and tensile strain regions that correlates with transitions on strain-stress curves. The maximum primary relative strain in the epoxy adhesive reaches 3.38 % and concentrates along the adhesive–steel interface
In accordance with GOST 25717-83 requirements, the shear modulus of 236 MPa and Young’s modulus are determined for the epoxy adhesive by B method and the t distribution with the confidence level of 5%. These parameters are used for a transition from empirical building to theoretically substantiated finite element analysis of the stress-strain state of the steel-to-steel connection.
The obtained results help to optimize the design of epoxy bonded steel-to-steel connections in engineering, promoting more continuous load, reduced weight and defects as compared to conventional techniques (welding and screw connections). This work confirms the efficiency of sanding of the steel surface in gaining the best adhesion and resistance to environmental impacts, which is relevant for the iron, aerospace and construction industries.
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Numerical investigation of the dynamic impact of hybrid basalt fibre on the damage and split way resistance of reinforced concrete aerodrome pavement

https://doi.org/10.58224/2618-7183-2025-8-6-5
Abstract
The study used Finite Element Analysis (FEA) to examine the influence of aircraft landing loads on the crack resistance of hybrid basalt fibre-reinforced aerodrome pavements. The study replicated a load from an Airbus A321neo on 25 distinct concrete mixtures, each incorporating different proportions of basalt micro and macro fibres. We measured the total deformation of each mix after 7, 14, and 28 days of curing. The results showed that all of the fibre-reinforced mixes had a significant and consistent decrease in deformation compared to the unreinforced control mix. Mix M11, which had 2% Basalt Microfibre and 1% Basalt Macro Fibre, was found to be the best mix. This particular hybrid combination consistently exhibited the lowest total deformation values throughout all three curing periods. For example, after 28 days, the control mix had a deformation of 0.0058265 mm, while Mix M11's deformation was only 0.0057363 mm. This numerical evidence shows that hybrid fibre reinforcement works together to make aerodrome concrete stronger and able to hold more weight. The results indicate that enhancing the hybrid basalt fibre content is an effective approach for creating pavements that are more resilient, long-lasting, and environmentally friendly, which is essential for enhancing safety and operational efficiency in the aviation sector.
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Heat and mass transfer in concrete mixtures during transportaion along the route «Manufacturer of liquid – phase solution – consumer of solid-phase concrete»

https://doi.org/10.58224/2618-7183-2025-8-6-6
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Abstract
The durability of concrete is a critical operational parameter that directly determines the service life of concrete structures. Achieving a concrete mixture with specified rheological and strength properties is a vital technological stage, as the quality of the initial material governs the load-bearing capacity of the final reinforced concrete elements. In the technological process, the transformation of concrete mixture components into a liquid non-Newtonian system with distinct rheological characteristics, followed by solidification into a structured composition, depends significantly on the variability of physico-mechanical, thermophysical, and structural-mechanical properties of both individual components and the overall mixture.
Developing comprehensive mathematical models that describe the entire technological cycle—from production to placement—poses a multifactorial challenge aimed at ensuring the design durability of construction structures. Particular emphasis is placed on modeling heat and mass transfer processes within heterogeneous concrete systems, as these non-stationary external influences critically affect the operational characteristics of the final material. Transport and hardening parameters heavily influence structural transformations within the cement stone, ultimately impacting strength and deformation properties. Effective resolution of this problem necessitates modern numerical modeling techniques that incorporate the rheological behavior of concrete mixtures and hydration kinetics.
The proposed mathematical and algorithmic framework underpins efforts to minimize concrete structure degradation by simulating rheological parameters during transportation and placement. A principal achievement is the creation of heat and mass transfer analysis algorithms that integrate predictive models with real-time monitoring data, laying a methodological foundation for future technological process control systems. The solutions further include optimization of logistical parameters under varying temperature and humidity conditions and the establishment of criteria to assess the structural homogeneity of concrete mixtures.
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