This paper presents the results of experimental studies on the punching shear strength of thick reinforced concrete slabs (600 mm) without shear reinforcement. The influence of the tensile reinforcement ratio (μs = 0,56% and 1,12%) on the load-bearing capacity and failure mode was investigated. It was found that a two-fold increase in the reinforcement ratio leads to an increase in punching shear strength of only 10,8%, indicating a reduced influence of this factor for "thick" slabs compared to "thin" ones. The complex stress-strain state of concrete in the support zone and the stress distribution in the reinforcement were analyzed. A comparative analysis of the experimental data with calculations based on regulatory documents (SP 63.13330, EC2, ACI 318, MC2020) was carried out, which showed a significant overestimation of the load-bearing capacity according to the SP 63.13330 methodology, especially for slabs with a low reinforcement ratio. It is concluded that it is necessary to account for the longitudinal reinforcement in the design models.

A method for solving problems in structural mechanics is presented, based on Cauchy's theorems The method is presented using simple examples: beam bending on an elastic foundation and vibrations of a system with one degree of freedom. Differential equations are presented in generalized functions, which allows taking into account boundary and initial conditions in the equations. The righthand sides of the equations written in this way contain parameters that determine both the specified boundary conditions and the unknowns. The integral Fourier transform is used in the solution.

To determine the unknown boundary conditions, the conditions for the analyticity of the Fourier images of the displacement function in the upper complex half-plane are used (the Cauchy integral theorem). Thus, a system of equations is obtained for obtaining unknown boundary conditions. When performing the inverse Fourier transform, the Cauchy residue theorem is used. As an example, the solution of oscillations of a system with one degree of freedom with different damping coefficients is given.

The features of the work composite steel and concrete structure with steel-plate reinforcement during bending are considered. The models are described, the features of the models, materials and their characteristics are given. The description of experimental equipment, schemes of testing and loading of structures is given. Schemes and types of fracture, graphical results of bending tests of models are presented. A comparison of theoretical and experimental data on the first and second groups of limiting states – strength, deflections, and crack opening width, has been performed. An assessment of the existing regulatory approaches in relation to composite steel and concrete structure with steel-plate reinforcement is given. Correction coefficients are proposed for the calculation for the second group of limit states of steel and concrete structure with steel-plate reinforcement.

The issues of the robustness of load-bearing structures under technogenic emergency impacts are currently becoming increasingly relevant in both domestic and global structural engineering. This is particularly true for compressed and compression-bent elements, including building columns. Buildings with a significant service life accumulate corrosion damage, which leads to local degradation of the mechanical properties of materials. This can substantially affect the ultimate load-bearing capacity and overall robustness of structural systems under dynamic loads. An approach is being developed to determine the strength of normal sections for eccentrically compressed columns with a small initial eccentricity under transverse impact. Corrosion is considered as a localized "spot" defect, within which the mechanical properties of both concrete and reinforcement may be degraded. The degree of degradation of the materials' mechanical properties is determined from experimental data obtained using accelerated corrosion schemes. Depending on the degree of corrosion, the effect of confinement on concrete deformations in the direction perpendicular to compression is taken into account. A verification comparison of the developed methodology with experimental data from dynamic tests of columns under transverse impact is provided. A calculation example for a corrosion-damaged column is considered.

A practical technique for determining the survivability parameter of reinforced concrete frame frame of a multi-storey building with complex-stressed elements under static-dynamic deformation caused by a special impact and an algorithm for numerical and analytical realization of this technique are presented. The values of parametric load, at which one of the criteria of special limit state occurs in the most stressed spatial section under the considered loading mode, are obtained from the solution of the system of canonical equations of the mixed method variant. In accordance with this method, the solution of the problem of nonlinear deformation of the frame system is constructed using the model of the substructure of the frame system described by the hinge-bar model, in which the places of possible disconnection of links are replaced by complex hinges, unknown angular and linear links. The proposed method of calculation of survivability of reinforced concrete frames with complex stressed elements satisfactorily describes the process of their deformation and exhaustion of bearing capacity of a structurally nonlinear frame system under the considered special impacts.

The absence of a scientifically-grounded theoretical framework for shaping the architecture of modern educational complexes impedes the transition of schools into such complexes. This transition represents an objective historical trend, as confirmed by our analysis of global experience in the design and construction of general education facilities offering all-day schooling services. The research aims to develop a theoretical model of an all-day educational complex for its subsequent implementation in the architectural design practice for both new and renovated facilities. These complexes are intended for the upbringing and education of Russian schoolchildren, their socialization, the development of a civic and patriotic stance, and the nurturing of creative initiative. This paper presents the results of theoretical modeling of an all-day educational complex—a new-generation architectural entity for general education. The theoretical model of the complex is structured as a tripartite framework, comprising social, functional, and typological levels. At the social level, user groups are identified, defined as territorial educational communities that will utilize the facility to carry out their activities. At the functional level, functional programs are proposed, leading to the formation of functional zones and clusters of spaces for program implementation. At the typological level, architectural-planning and volumetric-spatial models are developed for both the structural elements and the complexes as a whole. The study defines the core concepts of the research: "extracurricular activities," "all-day educational complex," and "center for extracurricular and supplementary education." Furthermore, generalized territorial-typological models of all-day educational complexes have been developed. The proposed theoretical model of an all-day educational complex can be applied in both new construction and the renovation of existing school buildings. While new construction and renovation impose significantly different requirements and design approaches, the findings of this work, encapsulated in the formulated theoretical model, allow for its implementation under varying conditions. The theoretical model presented for discussion in this work reflects the authors' idealistic vision for what a new-generation general education complex in modern Russia should be.

This article addresses the problem of reconstructing the medieval Insterburg Castle, located in the Kaliningrad region of Russia. It examines the importance of preserving this cultural heritage site and proposes a variant for its adaptation to modern use. The conducted analysis includes a study of the castle's technical condition, an assessment of its reconstruction feasibility, and the development of proposals for its preservation and functional application. The article explores various approaches to reconstruction, including museumification and functional reinterpretation, as well as architectural and planning solutions based on the principles of imitation and contrast. Significant attention is given to the discussion of the need to combine historical heritage with contemporary elements to create a harmonious architectural image. A set of architectural and structural solutions is proposed for the reconstruction of Insterburg Castle: the installation of a glass dome on metal columns; the erection of external walls and the construction of an atrium with stained-glass glazing, which will give the structure a sense of lightness and aesthetic appeal while also reducing the load on the foundation; the strengthening of the historic wall structures; and addressing the foundation problem by introducing a stylobate that will connect the preserved castle walls with the new structures. These measures will ensure the structures work as a single unit, enhance the overall stability and reliability of the facility, and enable the transfer of loads to the pile foundation.

The calculation section includes the determination of loadings and the definition of parameters for the sheet pile enclosure and the pile foundation. The proposed solutions are aimed at preserving the historical appearance of the castle, ensuring its functionality, and adapting it to modern operational conditions. These solutions are aimed at preserving the historical appearance of the castle, ensuring its functionality and adapting to modern operating conditions.

Contemporary theoretical and methodological models for the restoration of architectural heritage sites are typically based on specialized scientific principles. These principles define historicity, the maximum objectivity in recovering the original state, the preservation of authenticity, the assessment of the value of all stages of the asset's life cycle, among others. This article examines a novel approach to the content and principles for developing and practically implementing architectural heritage restoration programs within an urban context. This approach is founded on the overarching paradigm of conserving and developing the socio-techno-biosphere of the modern city. It is demonstrated that the successful advancement of urban renewal and environmental programs and projects, including the restoration and reconstruction of architectural monuments, is critically dependent on establishing effective implementation mechanisms. These mechanisms are based on a fundamentally new method: a unified urban planning approach to organizing the city's spatial structure. From a practical standpoint, as illustrated by the case study of the reconstruction and restoration of a Constructivist-era cinema building from the 1920s-1930s, this integrated strategy enables addressing restoration challenges within a unified context. This encompasses preserving the historical value of assets for future generations, safeguarding national architectural identity, enhancing the quality of the urban environment and human potential, and leveraging the educational aspect of studying urban history and cultural heritage.

The relevance of developing composite construction materials based on natural bentonite from deposits in the Chechen Republic is substantiated. The nanoscale size of the modifier based on bentonite powder from the Chechen Republic deposit, in combination with the hyperplasticizer Frem Giper S-TB, was confirmed using modern technologies and equipment. The objective of this work is to investigate the role of the surface tension of bentonite suspensions, both individually and in combination with the hyperplasticizer Frem Giper S-TB, on the strength and density of cement stone, as well as their interdependence. The materials used were the hyperplasticizer Frem Giper S-TB (manufactured in the Republic of Belarus) and natural bentonite extracted in the Chechen Republic. For the experimental research, Portland cement CEM I 42.5 N produced by JSC «Chechencement» was used as the primary binder. A reduction in the water-cement ratio (W/C) by up to 24% was demonstrated. This was achieved by lowering the surface tension of the mixing water through the use of a complex nanomodifier based on natural raw materials. The use of this complex nanomodifier showed a significant reduction in surface tension, with a minimum identified at concentrations of 2-4% by mass of water. Minimum surface tension values of 40-41 mN/m were reached. It was established that the strength of the sample with the combined introduction of 0.4% Frem Giper S-TB and 0.4% bentonite powder increased by 22% compared to the control sample. A further increase in the concentration of both bentonite and the hyperplasticizer adversely affects the strength characteristics of the cement stone. This is a result of excessive dispersion of cement during the mixing process with modified low-surface-tension water, and a decrease in the density of the cement paste due to the separation of cement grains by the formed micelles of the Frem Giper S-TB hyperplasticizer.