The article is devoted to the issue of preserving the architectural heritage of the outstanding Russian engineer V.G. Shukhov. Three objects are considered: the Moscow Radio Tower on Shabolovka, the "Shukhov Span" of the Sheet-rolling Shop and the Water Tower located in Vyksa, Nizhny Novgorod region. The main technical parameters of these structures and the results of their technical inspection are presented, emergency measures taken to ensure the safety of the Radio Tower in Moscow and recommendations for the restoration of all three structures with the transfer of the Sheet Rolling Shop and the Water Tower to the central part of the city Vyksa. It is planned to recreate the historical appearance of the buildings, as well as the improvement of the adjacent territory. It is supposed to restore the geometric shape of the cross-section by laser spraying of powdered metal, and only if it is impossible to restore the element, its replacement is provided. In order to preserve the historical appearance, the joints of steel structures will be on bolts imitating rivets.  Archaeological investigations are planned during the excavation, as areas of preserved cultural strata of the cultural heritage object "Manor-industrial complex, XVIII-XIX centuries" may lie within the boundaries of the construction territory (Vyksa).

The features of the static and dynamic behavior of rubber-metal vibration isolators planned for use for vibration isolation of buildings in a modern building complex are considered. 

The results of finite element modeling of vibration isolators are presented in order to determine the static and dynamic characteristics. Both single-layer vibration isolators and vibration isolators, including three rubber layers, are considered. As the calculation results showed, the presence of perforations significantly affects the bearing capacity of vibration isolators, significantly reducing it, however, the efficiency of such vibration isolators also increases compared to completely monolithic vibration isolators without holes. This is due to a number of reasons, one of which is the practical incompressibility of the rubber layers. In fact, rubber bodies can be subjected to compression only due to the deformation of the side surface, thus, by developing the side surface of the rubber layers, it is possible to achieve acceptable rigidity of the vibration isolator as a structural element, which will reduce the rigidity of the vibration isolation system. The spatial arrangement of the holes is also essential, since the placement of the holes close to the side surface of the rubber layer gives a significantly smaller effect compared to the placement of the holes in the center. In the process of calculation, it turned out that in the compressed rubber layers, the effect of the formation of pronounced zones of all-round compression is observed. The presence of central holes leads to the destruction of such zones in most samples, which makes it possible to reduce the first natural frequency of the vibration-isolated system to a greater extent, thereby contributing to an increase in the effectiveness of vibration protection measures. The choice of the hole configuration is an optimization problem, where, on the one hand, it is necessary to ensure the bearing capacity of vibration isolators acceptable from the point of view of vibration isolation for given dimensions of the vibration isolator in the plan, and, on the other hand, to minimize the rigidity of the system, thus increasing the effectiveness of vibration protection measures.

This article investigates the coefficient of moments redistribution in statically indeterminate RC beams through an experimental and analytical approach. Two-span statically indeterminate RC beams were tested under bending moment. A discussion of the results of the mode of failure, load-deformation, load-strain, and the coefficient of the moments redistribution were conducted. Moreover, the experimental results were compared to the analytical predictions of the related existing models, including the ACI 318-19 and CSA A23.3-19 codes, and others. The results show that the coefficient of moment redistribution is affected by the reinforcement ratio (μs1) and can be accurately predicted by a recent mathematical analysis. The experimental results also reveal that the moment redistribution capacity of the beams exceeds the values predicted by the other existing models.

Deformation models of materials are widely used in the calculation of reinforced concrete structures. At the same time, concrete compression diagrams are used, taking into account the descending branch. The analytical description of the concrete work diagram is associated with the determination of such concrete parameters as the initial modulus of elasticity; prismatic strength; extreme compression deformations at the top of the diagram; the value of deformations on the descending branch at 85% of the prismatic strength. The influence of alternating temperatures on reinforced concrete structures of buildings and structures leads to the development of destructive processes in concrete. At the same time, the question of the effect of cyclic freezing and thawing on the complete diagrams of concrete, including the ultimate compression deformations, remains poorly investigated. The determining factor affecting the deformation and strength properties of concrete under freezing and thawing conditions is its humidity. In this regard, studies have been conducted on the effect of cyclic freezing and thawing on the diagrams of the state of concrete of various humidity, the results of which are presented in this paper.

The paper considers the limit state function in the context of reliability analysis of corroded beams. Methods for determining the ultimate load limit for corroded beams are discussed. Various approaches to the determination of the limit state function are considered, including those based on statistical data on corrosion and modelling of stresses in a reinforced concrete beam. A general reliability assessment model for reinforced concrete structures should include corrosion propagation. Most previous studies have focused on one-dimensional diffusion problems with an assumed constant corrosion rate. A nonlinear corrosion rate model, unlike linear models, considers the corrosion current density not constant over the service life of a reinforced concrete structure. An approach to reliability analysis together with a nonlinear corrosion growth model is developed. In this paper, the main problems related to reliability under a nonlinear model of prestressed reinforcement rope corrosion of reinforced concrete beams are discussed. A function for the reduction of reinforcing bar diameter from time is presented. Sensitivity analysis is performed to determine the effect of corrosion growth parameters on the reliability index of reinforced concrete T-beam. The nonlinear corrosion growth model, together with other relevant probabilistic models used to describe random variables, was applied to analyze the reliability of a reinforced concrete crane girder. The expression of corrosion current density shows that the corrosion rate increases exponentially as the value of the design parameter of the model increases. To further evaluate the effect of the proposed time corrosion growth model on the reliability of reinforced concrete beam, two specific cases are considered. The first one is with fixed corrosion current density, and the second one is with fixed corrosion growth at a given time.

Modern approaches and requirements for the design and expert assessment of the buildings and structures state require the quantitative determination of their reliability indicators. This determines the relevance of the development of methods for calculating the reliability of building systems, taking into account their properties and operating conditions.

Corrosion damage to elements of metal structures can lead to loss of their functionality over time. The purpose of the research presented in the article is to identify and quantitatively describe changes over time in the reliability characteristics, according to the strength criterion, of an initially centrally tensile steel rod structural element of an annular section, taking into account uneven corrosive wear, which causes the occurrence of complex resistance of the rod, namely tension with bending. A calculation apparatus and an algorithm for determining the reliability and durability of an element were constructed using methods of reliability theory and the proposed spatio-time corrosion model. Calculations of these characteristics were carried out by varying the stochastic properties of the parameters of the rod’s cross section geometry, its stress state and the corrosion model at various degrees of corrosion factor aggressiveness. The loading of the rod was modeled by a stationary random function. The results of calculations of reliability, failure probability, corrosion coefficient and time density of failure probability are presented in graphs of the dependences of these values on time.

The influence of the main design characteristics of the rod and the corrosion damage model on the reliability and durability of the structural element was assessed. The effect of a significant increase in the probability of failure and a decrease in durability with corrosion wear, uneven along the contour of the section, was revealed, in comparison with the case of a constant thickness of the corrosion layer, with comparable values of corrosion coefficients.

The methodology and calculation results presented in the article can be used to obtain solutions to similar problems in other formulations (by cross-sectional shape, corrosion model, under non-stationary loading conditions, etc.), as well as to perform engineering reliability calculations when designing metal structures.

A spatial calculation model of a complexly stressed reinforced concrete element is constructed under the combined action of a transverse force and a bending moment. Analytical dependences are obtained for calculating the transverse reinforcement of such an element with inclined (transverse) rods under the stress state under consideration. The rectangular section is reduced to an equivalent box section with two cases of the compressed zone position. The computational model sufficiently fully reflects the physical phenomena of the force resistance of the crossbars of reinforced concrete frames in the limiting and exorbitant states established experimentally. The results of numerical studies of frame structures, the transverse reinforcement of which is accepted in the form of inclined or cross inclined rods when using the proposed and other calculation models, are carried out. A comparative analysis of the results obtained showed the effectiveness of a stricter account of the combined action of bending moments and transverse forces and the possibility of a noticeable reduction in the calculated transverse reinforcement of reinforced concrete structures under the stress state under consideration due to this. The proposed analytical dependences can be used to calculate reinforced concrete crossbars of structurally and physically nonlinear frames with their brittle destruction along an inclined section in exorbitant states.

To date, the existing architectural styles have been systematized with their modifications, subspecies and style trends in relation to thin shells and shell structures. There are several chronologies of the development of architectural styles. It has been established that the intensity and variety of the use of analytical and analytically non-assignable surfaces in the architecture of shell structures, thin shells and in the external forms of various structures can be divided into five time periods. The last fifth period was decided to be called "The revival of interest in shells and curvilinear structures, the emergence of new architectural styles." According to the research materials, it began at the beginning of the XXI century. This article shows that up to now 37 analytical surfaces out of more than six hundred known surfaces have been used. The authors constate the real situation in the architecture of curvilinear forms and show the increasing interest of architects and builders in such objects. It is shown that since 2000, 16 main architectural styles have been used, not counting the latest styles declared by architects, but designated by one or two structures. Analytical and analytically undetectable surfaces that have found application in real structures are listed with specific examples. The architects who participated in the design of the most significant buildings and structures of curvilinear forms at the beginning of the XXI century are indicated. The literature used contains 32 titles.

This article discusses the aspects of the formation and modernization of historical morphotypes of the block development of the central part of Voronezh during the post-war reconstruction (1945-1950-ies). The hypothesis is put forward about the importance in the present architectural and urban studies of ontological knowledge of the main stages of modernization of the architectural and planning structure of the modern historical urban center, including in the process of creating the principles of its functional and spatial organization. 

The object of this study is thearchitectural and urban planning environment of the historical center of Voronezh that has developed by the time of the post-war reconstruction period. A systematic retrospective analysis of the architectural and planning structure of Voronezh is carried out: the external and internal factors determining the principles of reconstruction of the historical urban center during the post-war restoration of the USSR as a complex multilevel object of the "population and environment" type are identified and fixed in accordance with the identified factors of the boundaries of the study; the parameters of the studied territory are systematized in a certain time period at various hierarchical levels, and the fund of successive historical and urban values expressed in material, spatial and functional equivalents is determined.

As a result of this study, the stable architectural and urban planning trends of spatial and functional modernization of the studied territory during the post-war reconstruction of Voronezh are determined, which are necessary for the organization of a correct reconstruction process at the present time. The historical-architectural and urban planning analysis carried out on the basis of historicalarchival and bibliographic studies allowed us to form a typology of historical morphotypes of the city's buildings. Voronezh in the period of post-war reconstruction, as well as to identify extreme modernizations that carry a historical and cultural code. The system principles of the post-war reconstruction of the architectural and planning structure in two directions have been formed, differentiated on the basis of typological groups of planning elements of the functional and spatial organization ofthe urban center identified as a result of the systematic approach in the period under consideration.

A study was made of the influence of a model biological environment of the products of the metabolism of filamentous fungi on the biostability of cement composites from industrial dry building mixes for outdoor and indoor work. The low resistance of samples without additional bioprotection to the influence of the biological environment was established. Relevant is the development of cement composites with biocidal additives to ensure resistance to biologically and chemically aggressive environments without reducing the strength properties. The degree of fouling of samples from various types of dry building mixtures in a model environment of metabolic products of filamentous fungi was determined. Eight composites of different composition were studied under the influence of 13 types of model medium. The stability of the samples was established at a concentration of medium components from 0 to 5% by weight. Tile adhesive "UNIS 2000", tile adhesive "Prospectors", putty "Prospectors", facade plaster "KNAUF" have fungus-resistant properties. Putty "CT29 Ceresit". Waterproofing "VodoStopGlims", plaster "IvsilGross" and self-leveling floor "Magma" are non-mushroom resistant. The most unfavorable concentrations of filamentous fungi metabolism products for the samples were revealed. The effectiveness of the use of polymer-based biocidal additives of the Teflex series (OOO SoftPROTECTOR, Russia) on the resistance of cement composites to biodegradation was revealed. The additives "Anti-Salt Wash", "For Metal" and "Universal" showed the greatest efficiency, their use provides fungi resistance and fungicidal properties of building materials.

In the publication, conglomerate building composites (concrete) are identified as heterogeneous solids with a hierarchically organized spatial-geometric structure with a characteristic dimension from 10-10 to 10-1 m, with a minimum of 5-6 scale levels and three types of substructure design that differ in scale, genesis and mechanics of properties manifestation. The first type is characteristic of the macro-, meso- and microscale levels and is taken in the form of a two-component “construction” of a spatially continuous matrix and discrete solid and gaseous (macropores) inclusions deterministically and stochastically distributed in it; the second type refers to the submicro-, ultramicro- and nanoscale levels and is believed to be in the form of a “microscale spatial structure” of new formations of a cementitious substance from consolidated individual crystalline differences; the third type, finally, corresponds to the atomic-molecular structure of new formations of the cementing substance. Characteristics of the distinguished types of substructures are given according to the scale of their components, the peculiarities of formation, the mechanics of manifestation of properties, design criteria and means of synthesis of each substructure. The patterns of formation of the fracture route in substructures of all types and substances of each scale level are analyzed. In this case, the development of the stress-strain state of the conglomerate composite according to the principle of energy dissipation, localization and increase (concentration) of stress is realized in the direction from the macro- to the atomic-molecular level of the structure of the composite, and the destruction itself and, accordingly, the formation of the crack route in time and in space of the composite passes in the direction from the atomic-molecular level to the macrolevel in a cascade through all intermediate structural levels. Within the framework of an integrated mechano-physico-chemical approach, the place of thermofluctuation theory (fracture physics) at the stages of breaking single atomic-molecular bonds and crack mechanics at the stages of development of micro- and macrodamage is shown. The possibilities of using theoretical principles of crack route formation to formulate and solve practical problems of designing and synthesizing optimal structures of conglomerate building composites are discussed.

In recent years, the search for and use of alternative binder building materials has become the subject of many studies both in Russia and abroad. This is due to the trend to reduce the harmful effects of the production of building materials and to more rational use of available raw materials. Fly ash, being a waste of the energy industry, accumulated in large volumes in ash dumps throughout Russia, is a promising material for use in the production of cement-containing building materials and products. The article provides a review of scientific literature and patents on the use of fly ash in various types of concrete, as well as in the production of dry building mixtures. On the basis of the review, positive and negative effects from the introduction of fly ash additives on the properties of concrete, ways to increase the efficiency of using the considered waste in the production of building materials were identified. The experimental part of the work presents the results of determining the strength and water resistance of heavy concrete samples with partial replacement of cement with fly ash obtained by burning coal at a new thermal power plant in the Kaliningrad region.