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Assessment of seismic response of a 29-storey building on raft and piled raft foundations considering soil–structure interaction

https://doi.org/10.58224/2618-7183-2026-9-1-1
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Аннотация
This paper presents a comparative analysis of the performance of raft and piled raft foundations using the case study of a 29-storey building designed for the seismically hazardous area of Grozny. The investigation is based on numerical modelling of the interaction within the “structure–foundation–multilayered soil” system taking into account the actual geotechnical conditions and dynamic properties of soil. Seismic loading is considered as a stationary random process. The analysis investigates the distribution of resonant frequencies of the system, the spectral density of the random acceleration function of the system, and its dynamic amplification factor. Frequency characteristics of the building were obtained using the LIRA-SOFT software package. The evaluation of the dynamic amplification factor was carried out by solving a stochastic problem of wave propagation in a multilayered medium.
The results demonstrate that the piled raft foundation reduces the dynamic response of the building. Despite its higher cost, the use of such a foundation is justified in the conditions of increased seismic hazard and weak soils. The obtained findings allow us to recommend a piled raft foundation as the preferred structural solution for high-rise buildings under engineering-geological and seismic conditions similar to those of Grozny.
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Prediction of concrete nonlinear creep using machine learning methods

https://doi.org/10.58224/2618-7183-2026-9-1-2
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Аннотация
Based on the experimental data of concrete nonlinear creep under high stress levels (40-80% of prismatic strength), this study explores the application of machine learning methods for predicting creep deformation. A recurrent artificial neural network (ANN) and the CatBoost algorithm were employed to model the time-dependent creep strain, using stress and time as input parameters. The ANN demonstrated high predictive accuracy, with training achieving a mean square error of 0.000154, and its generated creep curves showed an excellent fit with the experimental data. In contrast, the CatBoost algorithm, while effectively capturing the physical trend that creep strain increases nonlinearly with stress and decelerates over time, exhibited lower prediction accuracy than the ANN. Feature importance analysis within the CatBoost model highlighted the significant influence of lagged stress parameters and time-squared terms, aligning with the nonlinear physical nature of concrete creep. The results confirm the strong potential of machine learning, particularly recurrent neural networks, for modeling complex nonlinear creep in concrete, even with limited datasets. Future work is suggested to incorporate concrete strength class and loading age as additional parameters to enhance model generalizability.
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Salt spray corrosion test, hardness test, and abrasion test of nanomodified phosphate coatings

https://doi.org/10.58224/2618-7183-2026-9-1-3
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Аннотация
The development of new rust converter formulations is a relevant issue that contributes to increasing the competitive edge of domestic products and sustainable development of various branches of the economy. The aim of the study is to determine the corrosion resistance of various phosphate films on the metal surface when exposed to salt spray, as well as to determine hardness and resistance to abrasion (scratching).
Materials and methods: Metal rods are coated with a film using a special surface treatment with orthophosphoricacid-based rust converters. The study introduces a new experimental rust converter formulation containing a Lewis acid (or its salts) and dispersed nanopowders of oxide and other inorganic/organic complexes.
Results: Tests revealed that full-scale corrosion of metal rods treated with the experimental formulations began after 9 and 10 days, while untreated rods were showing signs of corrosion as early as on the second day. These films also demonstrated a hardness of 490 HV (modified scale of a TEMP-4 hardness tester) and withstood a maximum indenter load of 4.1 kg (measured with PROMTPP-1518) based on ISO 1518 method (scratching with a needle).
Conclusions: Based on the test results, it was concluded that the modified phosphate films exhibit high hardness and resistance to needle scratching according to ISO 1518 method, and also exhibit increased corrosion resistance to salt spray. However, the demonstrated resistance is insufficient for exposure to a salt spray chamber for 42 days.
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Effect of curing regimes on phase composition and compressive strength of geopolymer binders based on ash and slag waste from thermal power plant

https://doi.org/10.58224/2618-7183-2026-9-1-4
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Аннотация
This study focuses on the investigation of compressive strength of geopolymer binders based on alkali-activated ash and slag waste from thermal power plant. It has been found that the significant factors affecting the mechanical strengths are the reactivity of the precursor and curing regimes of geopolymer binders. First of all, the quantity and the structural characteristics of amorphous phases in these materials play a crucial role in determining the mechanical performance. According to the X-ray data, both fly ash and slag as well as the geopolymers based on these precursors, demonstrate the presence of an amorphous hump. The quantity of amorphous phase in slag component (70.4%) is higher than in fly ash one (63.9%). Besides, compared to the original slag, the radius of the first coordination shell for the “low-angle” amorphous phase R1 = 7.3 Å is higher than that of the fly ash R1 = 7.0 Å. This indicates that the slag component demonstrates the presence of regions of increased free volume. On the other hand, the proportion of the crystalline phase in the original slag is 29.6% in comparison with fly ash (36.1%) and is represented primarily by silicon oxide along with minor amount of hematite and magnetite. It has been determined that a sharp decrease in the crystalline phase content with increasing the heating medium temperature and pressure for slag-based geopolymers is observed. The geopolymer obtained by autoclave curing contains only 1.8% crystalline inclusions. DTG analysis indicates that the peaks corresponding to the geopolymers cured under autoclave regimes (both based on fly ash and slag components) are deeper and broader in comparison with binders cured under elevated temperature and atmospheric pressure. The compressive strength of slag-based geopolymer samples is much higher than of ash-based ones regardless of the curing regime. This is due to the properties of slag component: improved reactivity – the higher proportion of amorphous phase and aluminum oxide, lower water demand – the proportion of loss on ignition is practically negligible.
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Influence of heat resistance of the enclosing structures of a heated room on the choice of the type and location of the heating device

https://doi.org/10.58224/2618-7183-2026-9-1-5
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Аннотация
The article examines the influence of heat resistance of enclosing structures on the choice of type and location of heating devices in the room. The main attention is paid to the relationship between the thermal characteristics of fences and the method of heat transfer of heating devices. The paper considers two main types of heat transfer: convective and radiative. It is shown that at low thermal stability of structures, it is advisable to use devices with a predominant convective heat transfer (convectors, panel radiators), and at high – with radiation (radiators, underfloor heating, infrared heaters). A mathematical model of spatial non-stationary heat transfer in a heated room is developed, taking into account various thermophysical characteristics of enclosing structures and the type of heat release sources. The study of the amplitude of fluctuations in the temperature of air and internal surfaces, depending on the type of heating device, is carried out. The practical significance of the work is the development of scientifically based recommendations for the selection and placement of heating devices, taking into account the heat resistance of enclosing structures. The results of laboratory tests confirm the theoretical conclusions and demonstrate the nature of the temperature distribution in the room under various heat exchange conditions. The results of the study show that the correct choice of the type and location of the heating device allows you to ensure uniform heating of the room, minimize energy consumption for heating and create comfortable microclimate conditions.
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Features of using national symbols, geometric forms, decorative elements, and color schemes to reflect state identity in the architectural composition of diplomatic missions

https://doi.org/10.58224/2618-7183-2026-9-1-6
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Аннотация
The visual identification of diplomatic missions has gained particular importance in the context of globalization and intercultural interaction. Embassy architecture represents functional structures and a powerful means of expressing national identity. However, professional practice still lacks a consistent system of criteria for selecting architectural and symbolic elements that reflect the unique characteristics of the sending state. The focus of this study is on identifying architectural approaches to integrating national symbolism into the design of modern embassies.
The methodological foundation of this study is a qualitative and quantitative approach that includes the selection of case studies, comparative architectural analysis, and expert surveys. The research identifies stable categories of symbolism: official (flag, coat of arms) and secondary (historical style, color schemes, geography). An analysis of diplomatic missions in various countries has revealed that architects typically employ three main strategies: the use of dominant structural forms, the incorporation of traditional decorative elements, and the symbolic integration into the local context.
The results confirm the importance of national color schemes and geographical metaphors in creating a recognizable image. The conclusions emphasize the need to find a balance between national identity and contextual appropriateness, as well as respect for the architectural traditions of the host country. The study highlights the architectural tools of soft power and proposes a systematic approach to designing diplomatic missions as spaces for representing statehood.
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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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Аннотация
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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Аннотация
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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Аннотация
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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Аннотация
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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