Introduction. The paper highlights vulnerability of industrial facilities, such as process pipe racks, to increasing frequency of UAV terrorist attacks and other negative factors that can lead to an emergency situation and subsequent progressive collapse.

Aim. To develop design solutions for protection against progressive collapse in a design emergency situation with ensured geometric immutability and stability of intermediate double-hinged supports of a temperature block in the case of excluding an anchor support from the design scheme (local destruction).

Materials and methods. A review of relevant normative documents on the research topic was carried out. The survey experience was used to analyze the design solutions of recently constructed process pipe racks.

Results. Having analyzed the regulatory documents on the research topic, we assume that the lack of detailed recommendations and calculation methods for stability against progressive collapse of process pipe racks generally reduces the reliability of newly constructed and existing reconstructed facilities. A frequently encountered combination of a temperature block in a highly critical process pipe rack with one anchor support and multiple intermediate double-hinged supports interconnected by split span structures or struts appears disadvantageous in terms of failure to ensure the geometric immutability and stability of the intermediate double-hinged supports of the temperature block in a design emergency situation with the anchor support excluded from the design scheme (local destruction).

Conclusions. The developed design solutions ensure protection against progressive collapse in a design emergency situation and maintain geometric immutability and stability of intermediate double-hinged supports of a temperature block in the case of excluding an anchor support from the design scheme (local destruction). Applications for utility patents on the developed engineering solutions have been filed.

Introduction. Improving the reliability and mechanical safety of buildings in seismically hazardous regions is one of the priority tasks of contemporary construction. The most promising direction in ensuring seismic resistance of buildings is recognized as seismic base isolation systems reducing seismic loads on the building structure. The present article examines the problem and emphasizes the relevance of studying the behavior of buildings and structures with seismic base isolation systems under real seismic impacts, as well as provides the assessment of their technical condition after seismic events.

Materials and methods. The presented results of assessing the consequences of destructive earthquakes are analyzed for the behavior of base-isolated buildings and effectiveness of seismic base isolation systems. Particular attention is paid to the consequences of devastating earthquakes that occurred in Chile (2010), New Zealand (2010), Japan (2011 and 2016), and Turkey (2023), when the presence or absence of seismic base isolation systems significantly affected the safety of critical buildings and structures.

Results. Seismic base isolation systems can significantly reduce inertial seismic loads, thus ensuring the operability of buildings even under impacts exceeding design levels. All contemporary base-isolated buildings considered in this paper withstood seismic impacts, including those above the limits, without loss of functionality and operational suitability. An exception was the case in Turkey, where the recorded damage to a base-isolated building was caused by violations of technology and errors made at the construction stage.

Conclusions. The results of the study indicate a high efficiency of contemporary seismic base isolation systems for ensuring the reliability and mechanical safety of buildings under seismic impacts. The main advantages of using seismic base isolation systems include the reduced damage to load-bearing and enclosing structures and maintained functionality and serviceability of buildings during and after seismic impacts, which is especially considerable for critical infrastructure. The importance of proper design, construction, and maintenance of base-isolated buildings is noted.

Introduction. The current steel structure standards (SP 16.13330.2017) propose two methods that are used to solve the stability problem of frame structures: unified nonlinear systems and the effective length method. The former is not widely used, making the latter the primary approach for calculations. However, the current code contains only a few calculation schemes for determining the effective length factor, which does not fully address current engineering needs. This limitation makes it difficult to find quick solutions and necessitates the use of numerical analysis. Furthermore, the effective length method provides reliable results, but it takes more time to perform the calculations. This paper proposes a pathway for developing the effective length method and provides specific examples of problem-solving. This approach addresses a significant number of typical cases for single-story buildings and provides the necessary theory for solving multi-story cases.

Aim. This article aims to develop the effective length method.

Materials and methods. Development of effective length factor equations through modification of the shift method and comparison of analytical solutions in the LIRA-SAPR Software complex.

Results. The analytical work presented here offers a set of equations that support the development of the effective length method. These solutions complement document SP 16.13330.2017. The numerical analysis results confirm the obtained analytical solutions.

Conclusions. There is potential to expand the code of practice for steel structures, SP 16.13330.2017.

Introduction. The article presents data on the activities carried by the Research Institute of Building Constructions named after V.A. Koucherenko from July 2022 to March 2024 during the installation of a 210 m high radio and television transmitting tower in Vladikavkaz, Russian Federation. The most stressed structural elements located at 1.700 and 40.047 elevations were equipped with mechanical strain gauges to collect data on the stress-strain state of the whole structure. In addition, data of the geodetic survey performed during construction were analyzed.

Aim. To conduct stress-strain state monitoring according to the method developed by the Research Institute of Building Constructions named after V.A. Koucherenko for individual structures and critical components of an antenna tower, as well as for early warning and timely preventing possible emergency situations during its construction.

Materials and methods. The article presents drawings of metal structures and photographs of measuring instruments used during construction.

Results. Mechanical safety of the tower steel structures was ensured by monitoring the stresses of their most heavily loaded elements, as well as their movements and deformations.

Conclusions. The analysis of the stress-strain state measurements showed that the stresses and existing deviations of control points from the design position are within the permissible values specified in the regulatory documents in force on the territory of the Russian Federation.

Introduction. This article presents the validation of using field fire modeling to evaluate the effectiveness of structural fire protection for cable ducts in nuclear power plant (NPP) premises.

Aim. This article aims to provide computational and analytical validation of design solutions for protecting safety systems, particularly the physical separation of cable routes for different safety channels.

Materials and methods. In this study, the field method was used to calculate local fire parameters within cable structures made from fire-resistant materials with a regulated fire resistance limit.

Results. Based on an analysis of experimental data regarding the development of fires in enclosed cable routes, conclusions were drawn about the specifics of fire development within cable trays. Computational and analytical studies that used the field method to calculate fire dynamics expanded the scope of the research and identified typical fire parameters in cable trays made from modern, fire-resistant materials. The analytical method presented in this article was employed to validate the effectiveness of structural fire protection for cable ducts in NPP premises.

Conclusions. Computational and analytical studies of fire behavior in cable ducts are important for developing design solutions for constructing, reconstructing, and making major repairs to cable systems in nuclear power plants. These studies can validate fire protection requirements for cable routes and structures during the design and construction of NPP. The results may also be used to develop or refine regulatory documents that ensure fire safety in NPPs under construction. The results are also relevant for developing design solutions for constructing, reconstructing, and making major repairs to cable systems, as well as for replacing and re-laying cable products in operating NPPs.

Introduction. Inclined shaft headframes are among the most critical types of surface mining structures. The duration of construction and assembly of these structures directly affects the overall efficiency of the enterprise. Therefore, investigating the changes in the stress-strain state of steel headframes during installation by the pushing method is particularly relevant today, as it can help reduce the construction time of these structures.

Aim. This study aims to analyze the influence of assembly loads on the stress-strain state of the tower metal headframe during the moment of pushing.

Materials and methods. A BIM model was created in the Tekla Structures software for information modeling in order to analyze the structural scheme of the construction with the installed equipment. This model provides a more accurate assessment of the mass of the structure. Numerical studies of the inclined headframe were conducted using domestic software and the LIRA-SAPR 2024 computational complex. The system under consideration is presented in a general form, with deformations and main unknowns represented by linear displacements of nodal points along the X, Y, and Z axes, as well as rotations around these axes.

Results. An analysis was performed to determine the loads and influences applied to the structure while it was being pushed. The actual behavior of the structural elements was taken into account. The headframe is 85 meters high and has a total mass of 8,028 tons. A mathematical model of a two-bracing skip-cage headframe was developed to assess the influence of installing the structure by the pushing method. Considering the sliding friction coefficient, five jacks with a capacity of 1,000 tons each were selected for installation. The jacks are installed on the axes with the greatest load on the rolling path. The obtained results enable the selection of equipment for the pushing operation.

Conclusions. The calculation revealed that the retention coefficient is 13.06 in the direction of the tower headframe pushing, meeting the requirements for overturning resistance. Analysis of the stress-strain changes in the skip-cage headframe during installation using the pushing method revealed the need for five 1,000 ton hydraulic jacks. Adjusting the jack pressures on each axis prevents rotation of the entire structure and subsequent jamming of the pushing stand. Moreover, when these structures are being pushed, it is essential to remove the bracing that is perpendicular to the movement of the headframe. This will result in a reduction of the number of rolling path axes.

Introduction. This article presents a feasibility assessment for adding seven floors to residential towers А, Б, and В of the Akadem-Palace mixed-use complex in Moscow, based on static pile load test results. The decision to resume construction was part of Moscow renovation program. The multifunctional Akadem-Palace complex was designed as an integrated building ensemble comprising three high-rise towers (А, Б, and В), which are connected by a three-story above-ground stylobate and a four-level underground parking garage. Towers A and Б have 25 floors above ground, and Tower В has 32 floors.

Aim. Field pile load tests were conducted to confirm the bearing capacity of piles required by the new design and to assess the feasibility of adding extra floors to the residential towers.

Materials and methods. The tests were performed using the maintained load test method, in accordance with State Standard 5686-2020, with the existing foundation slab of each tower serving as the reaction system. The load was applied in increments using a jack with a capacity of 200 tons.

Results. The pile load tests showed that all piles have the required bearing capacity.

Conclusions. The pile load test results confirm the feasibility of constructing additional floors on piles separated from the tower pile caps.

Introduction. In contrast to homogeneous materials, fracture of layered masonry systems starts throughout the entire volume and not from the surface. This is due to a special boundary space emerging at the layer junction with the properties significantly different from those of both contacting materials. Despite the considerable number of works devoted to the features and patterns of its formation, the boundary space as a key factor in the fracture of the masonry system as a whole is still little touched upon.

Aim. To develop an approach to the facture mechanisms of layered porous masonry systems in cultural heritage objects operated for a long time.

Materials and methods. The presented model analyzes the main physical fracture mechanisms in the interlayer boundary space of the masonry system.

Results. Areas of sharp pore changes block transport of liquid and its evaporation. Impurities contained in the liquid medium and accumulated in the evaporation zone reduce the pore size and eventually contribute to the initiation of shrinkage-deformation (sorption) and crystallization mechanisms of fracture.

Conclusions. The facture processes in layered masonry systems are determined by the initial existence and further development of internal evaporation zones. These microzones are associated with boundary areas abundant at the layer junctions within the structure. In this regard, fracture processes develop simultaneously throughout the entire volume of the structure, being limited only to areas inaccessible for direct moistening. Thus, the fracture of layered masonry systems is self-developing and mainly determined by the access of a liquid medium.

Introduction. Despite its widespread use, wood is relatively weak. This has led to the development of methods to enhance its properties. This article examines two primary methods of modification: thermal treatment and impregnation with polymer compounds. Thermal treatment increases resistance to decay and reduces water absorption. Impregnation provides protection against biological agents, enhances wear resistance, and achieves nearly zero water absorption.

Aim. This paper aims to compare the physical, mechanical, and strength properties of untreated, thermally treated, and polymer-impregnated pine wood.

Materials and methods. Natural compression tests were conducted on second-grade pine wood specimens along the fiber direction. Vertical compressive stresses and deformations were recorded. The tests were performed using a hydraulic press with a maximum load capacity of 50 tons. Strain and stress measurements were taken using a strain gauge.

Results. During the in-place tests, the physical-mechanical properties of untreated, thermally treated, polymer-impregnated, and both thermally treated and polymer-impregnated wood were determined. The ultimate strength of the samples was identified and graphs of relative deformations were constructed to show changes in wood strength limits during the elastic stage of material behavior. According to the in-place test results, the elastic stage of wood compression extends up to 120 kN.

Conclusions. In-place tests revealed that thermal treatment and polymer impregnation of wood results in reduced deformability and increased brittleness and friability of the material, as evidenced by the nature of sample failure. Additionally, there is a 5–10 % decrease in material strength and elastic modulus. However, wood modification enhances protection against biological agents and moisture, thereby extending the service life of the structure.

Introduction. The construction industry is rapidly transitioning from traditional computer-aided design (CAD) to building information modeling (BIM), which allows for detailed modeling with real accuracy. BIM specifies not only the geometry of an object, but also its materials and characteristics. Construction projects created using BIM technologies can automate cost estimates, significantly improving accuracy and reducing time expenditures. However, cost estimation specialists have not yet been fully integrated into BIM processes.

Aim. The article aims to determine the feasibility of using software to automatically generate cost estimation documents from BIM models and identify the pros and cons of using it in the operations of a construction organization.

Materials and methods. An analysis was conducted of the software market offering automated cost estimation based on digital models. Selected programs were tested, and relevant publications by other researchers were examined.

Results. The software packages BIM-smeta ABC, 5D-smeta, BIM WIZARD, and Larix were evaluated. BIM-smeta ABC is user-friendly, but it operates directly within the model, which may compromise its integrity. 5D-smeta and BIM WIZARD allow designers and cost estimators to work in separate spaces, preventing estimators from directly manipulating the model. Additionally, BIM WIZARD offers 3D visualization capabilities for cost estimators. Larix enables automated calculations based on predefined logical sequences, which makes the initial setup process more labor-intensive for company-specific needs.

Conclusions. Automating cost estimation in BIM modeling provides the greatest benefits to companies that strictly adhere to internal design standards, especially the Employer's Information Requirements (EIR) and the BIM Execution Plan (BEP). In such organizations, the estimation process can be reduced to just minutes. Conversely, companies lacking such standardized design systems may require significant time and resource investment for implementation.

Introduction. The article discusses the structure of Russian classifiers for technical, economic, and social information. Proposals for the formation of a structure and approaches to classification are given for use in a construction information classifier. Algorithms for applying the construction information classifier are considered.

Aim. To give proposals for the formation of a structure and approaches to classification for use in the construction information classifier.

Materials and methods. Russian classifiers, their purpose, structure, and development prospects are analyzed. Principles of algorithms for applying the construction information classifier are proposed based on the performed analysis.

Results. The given proposals consider the formation of a structure and approaches to classification for use in the construction information classifier.

Conclusions. As a result of the conducted study, we propose to replace the construction information classifier with a construction classification system. This proposal implies coordination of existing industrial and inter-industrial classifiers, thus eliminating the irrational increase in the work time for classifying elements and attributes of information and digital information models. In addition, this proposal falls within the paradigm of applying a unified system for classification and coding of technical, economic, and social information.