The actual problem of resistance of near-reinforcement zone of concrete is solved as a problem of volumetric stress-strain state with "closure" of output integral parameters of this zone on the rod scheme of the whole reinforced concrete element synthesizing hypotheses and dependencies of various disciplines of mechanics of solid deformation body, including fracture mechanics. The calculation model of the reinforced concrete element takes into account the effect of reinforced concrete of prof. Vl.I. Kolchunov describing the mechanism of formation and development of transverse and longitudinal cracks. In this case, generalized hypotheses of linear and angular deformations for warping and gradients of jumps of relative mutual displacements of reinforcement and concrete are adopted. New functionals of reinforced concrete are constructed, which are consistent with the ideas about resistance of crosssections of rod elements in near-reinforcement zones. Physical equations for a concrete matrix modeled between transverse cracks are written. The displacement components for the near-reinforcement area are found in relation to the crack opening width at the boundary of the "concrete-reinforcement" contact in transverse, longitudinal and radial cracks, respectively. The use of the accepted assumptions and multi-level calculation scheme for the near-reinforcement region significantly brings the calculation model closer to a real assessment of physical phenomena.

Under emergency situations associated with sudden failures of the load-bearing elements of the structure, torques may additionally occur in the columns due to the specifics of the structural design of the buildings. Thus, the columns may be in a complex stress-strain state. The objective of this study was to develop a semi-analytical design model for analysis of the stability of reinforced concrete columns subjected to compression with torsion as a result of an accidental action. For achieving the objective, authors formulated the initial hypotheses, developed the determining equations for calculating the stability of a reinforced concrete column subjected to compression with torsion. To validate the reliability of the proposed model, it has been compared with the results of modeling in the software complex Ansys. Analysis of the data showed that the largest difference between the results was up to 8.08% for the case P = 0.4·Pcr,e = 126.6 kN. The smallest difference of 3.6% was for the case P = 0.9·Pcr,e = 284.85 kN. It has been shown that as the torque increases, there is a decrease in the value of the critical force causing loss of stability. This is due both to the action of the torsional pair of forces during the distortion of the rod and to the decrease in the mechanical properties of concrete under the combined action of normal and tangential stresses.

The article considers creation of elastic self-adhesive radio absorbing materials for frequency range of 2-7 GHz. Carbonyl iron is widely used in the production of radioabsorbing materials. Materials with this filler have a low absorption of electromagnetic radiation, and more reflect it. The main advantage of this filler is that it is produced by domestic manufacturers in industrial volumes. Another filler used for the production of radioabsorbing materials is carbon fibre. Materials on this filler have a high absorption coefficient of electromagnetic radiation, but operate in a very narrow frequency range. Therefore, in order to increase electromagnetic absorption and extend the frequency range, a certain amount of carbon fibre is introduced into the composition of the radioabsorbing material containing carbonyl iron. It is shown that in this case absorption of electromagnetic radiation reaches 93%. The material is intended for protection of premises and equipment against electromagnetic radiation.

The paper presents a physical and computational model for determining the parameters of limit states of reinforced concrete structures under complex stressed state - bending with axial and shear forces. Based on the adopted scheme of cross-section discretization and A.R. Rzhanitsyn's theorem of duality between force and deformation parameters, the forward and backward transfer for determining the coefficients of the stiffness matrix of reinforced concrete rod structures with inclined and normal cracks have been constructed. Stiffness of structures in the zone of inclined cracks is determined using the model of composite strips which separate the zone with inclined cracks. The hypothesis about the character of deformation distribution in a complex-stressed reinforced concrete element with inclined cracks is accepted.For this model the conditional shear modulus is obtained, which allows to determine the average relative linear and angular strains of concrete and reinforcement at the point adjacent to the shear joint between inclined cracks. Based on this model and using the experimentally obtained value of the relative shear in the inclined crack, the dowel forces in the reinforcing bar intersected by the inclined crack were determined. The application of the obtained analytical relationships in the practice of designing reinforced concrete structures allows not only to clarify significantly the definition of displacements and width of opening of inclined and normal cracks, but also to maximize the convergence of the design and physical model based on experimental data.

The article discusses the problems of improving the quality of the living environment in the special conditions of Palestine, as well as the theoretical foundations of programs (vectors) for the transformation of residential areas in the formation of an architectural and landscape complex based on a model of complex schemes of the environment-regulating system. Natural characteristics and human activity are the main elements of this system since their interaction is a condition for transformation in accordance with the principles of architectural and urban planning organization of residential development while maintaining the similarity, integrity, and effectiveness of interactions based on the principles of mutual influence and interdependence of old and new. Cases of contradictions and differences are identified on the basis of a comprehensive assessment of the development site in planning, functional, and compositional aspects, according to the principles of interaction between old and new. At the same time, it is determined how the formed elements of the environment as a result of human activity function under the influence of natural characteristics. As a result, areas of internal discomfort are identified. Development of a program of targeted transformations of the characteristics of the residential urban environment based on a step-by-step analysis of the interaction of the main elements of the system, the ultimate goal of which is to improve the quality of urban space. Identification of the environment-forming potential of the territory determines a method of measures in accordance with climatic, aesthetic, and environmental changes in the metropolitan area. Based on the principles of architectural and urban planning of comfortable residential areas, according to the principle of value and the direction of analogy, the environment-forming potential of the territory is determined. This is done by analyzing the mutual influence of natural characteristics and human activities. In conclusion, based on the study, trends are identified to improve the development and comfort of products located in accordance with accepted priorities and specific requirements.

With the help of probabilistic modeling, the issues related to the assessment of the robustness of structural systems made of prefabricated and monolithic reinforced concrete in an accidental design situation are considered. The paper considers the concept of analyzing the reliability of structural systems and differentiating risks in accidental design situations. The existing probabilistic models of the basic variables included in the functions of loads and resistances are analyzed. Statistical parameters of the uncertainty of the resistance model are obtained and integrated in the form of a basic variable with probability modeling. Probabilistic modeling of structural systems made of precast and monolithic reinforced concrete, designed according to the current standards of the Republic of Belarus, was carried out using the Monte Carlo method. The functions of the limiting state of the structural system in an accidental design situation with the sudden removal of the central column of the first floor are determined. As a result, values of failure probabilities and corresponding reliability indices were obtained for the considered constructive systems.

The main causes of the destruction of the front brick are considered. It is indicated that the properties of ceramic products during their operation in masonry largely depend on the quality of the preparation of the clay mass. Seasonal freezing of clay improves its molding and drying properties. The height of the cone during seasonal storage of clay for the climatic conditions of the Moscow region should be no more than 6 meters. It is confirmed by calculation. A critical analysis of the theory of chemical destruction of ceramic bricks during the interaction of alkalis with oxides of silicon and aluminum of the amorphous phase is presented. Calcium and magnesium ions have a much lesser effect on the corrosion processes of bricks because of the formation of easily soluble silicates and aluminates compared to sodium and potassium ions. It is proposed to separate the requirements for frost resistance of facing bricks is proposed depending on the climatic conditions of the construction.

The use of numerical models to analyze the behavior of steel elements has undeniable advantages and opens up a number of promising areas for the study of complex or new design solutions. The development of computer technology and software gives this direction a new stage of development - the use of numerical models in everyday design. For wider use of numerical models and ensuring comparability of results, it is important to develop universal principles for constructing numerical models with subsequent regulation in normative documents. Within the framework of this study, emphasis is placed on the use of numerical models on a par with classical (formula) models, and first of all, for this purpose, a review and systematization of the most important parameters of numerical models of load-bearing capacity is carried out. The instructions on the purpose of the properties of materials, the type of the final element, the quality of the mesh, the size and shape of imperfections applied to steel structures are presented. The results obtained are of interest for further research on the unification of the requirements for the parameters of numerical models and their verification based on experimental data with the calculation of statistical characteristics of the uncertainty of the numerical model.

The article presents the results of theoretical studies of reinforced concrete beams, taking into account the limitation of horizontal displacement on supports under short-term dynamic loading. In studies, the deformation of the structure is considered in the conditionally elastic and plastic stages. It has been established that the presence of thrust leads to a significant increase in strength and a decrease in the deformability of structures, both in the conditionally elastic and plastic stages. The paper reflects the results of a numerical calculation of reinforced concrete beam structures with thrust under short-term dynamic loading based on the obtained analytical dependencies. The effect of the thrust reaction, namely the rigidity of the support contour, on the dynamic coefficient of reinforced concrete structures is considered in comparison with structures without expansion. The results of numerical studies indicate a positive effect of the expansion reaction in dynamically loaded structures at all stages of their dynamic deformation.

In the practice of calculations of compressed reinforced concrete elements for static effects, a number of questions important for determining the deformations and bearing capacity of these elements still do not have definitive and unambiguous answers. First of all, this is the problem of reliable accounting for the long-term effect of the external load. Unlike bending elements, the bearing capacity of compressed rods depends on the time they are under load. The article deals with the influence of flexibility, the coefficient of reinforcement under long-term load on the decrease in the bearing capacity of a reinforced concrete compressed rod. A calculation method is proposed to determine the long-term compressive force that provides a given period of safe operation of reinforced concrete columns. The dependence of the ratio of the level of long-term action to the short-term breaking load on the deflections of compressed rods is revealed. An analysis of experimental studies was carried out, indicating that the value of this ratio depends on the eccentricity of the longitudinal force, as well as data on the magnitude of the reduction in the long-term resistance of the columns. Dependences of the stiffness ratio of the column under long-term and short-term external load on the flexibility of the rods, which is laid down in the current regulatory documents, and which is the determining factor in deciding whether to take into account the long-term nature of loading, are obtained.