The article considers the possibility of using the vibration-damping coefficient to determine the concrete class of reinforced concrete beams without prestressing reinforcement in the elastic stage of work. It is proposed to use this parameter as a characteristic that takes into account energy losses in an oscillatory system. It is likely that a change in the class of concrete will have a direct effect on the intensity of the damping of vibrations, since with an increase in the class of concrete the elastic properties of the structure begin to prevail over the plastic ones. Providing the same conditions of support and control of experimental designs, energy losses due to various physical and deforming properties of the products will be fully manifested, and the damping coefficient of vibrations will allow determining these properties with less errors and greater stability compared to ultrasonic or mechanical methods. A method has been developed for determining the class of concrete, based on the use of reference structures and constructing an analytical dependence of the damping coefficient of vibrations on the class of concrete. For the studied type and size of reinforced concrete structures, a smaller error in determining the class of concrete is obtained in comparison with known methods.

It is proposed a complex resistance computational model of reinforced concrete constructions in buildings and structures under the action torsion with bending. It consists of from the block near the support (formed by a spatial crack and a compressed concrete zone closed by it - a spatial section k) and a second block, which is formed by a vertical cross section I-I passing perpendicularly to the longitudinal axis of the reinforced concrete element along the edge of the compressed zone, which closes the spatial spiral-shaped crack. The case when the greatest influence on the stress-strain state of structures has the effect of torque is considered (case 2). In this case, as the calculated forces are taken into account in the spatial section: normal and tangential forces in the concrete of the compressed zone; components of axial and “dowel” efforts in the working reinforcement, intersected by a spiral spatial crack. The resolving equations are constructed that form a closed system and the Lagrange function is unified. Using the partial derivatives of the constructed function with respect to all the variables entering into it and equating them to zero, an additional system of equations is constructed. The dependence is obtained after the corresponding algebraic transformations, that allows us to search for the projection of a dangerous spatial crack.

Systems based on thin-walled galvanized profiles and effective heaters are widely used as wall fencing at present stage of development of enclosing structural systems. Wall fencing based on one-element assembly is most widespread. At the same time new solutions in the form of panels assembled from prefabricated elements are appeared. The latter in addition to technological advantages in comparison with the one-element assembly wall fencing have increased bearing capacity and rigidity. This article presents a constructive solution of a self-supporting wall panel based on cassette profiles and deck profiled sheets, combined into a single spatial structural system. The purpose of the work was to scientifically justify and experimentally confirm the operability of a new structural solution of the panel based on the cassette profile. The object of the study is a wall fence (panel) based on such profiles. Research methods: numerical and analytical methods, experimental studies of the full-scale model, graphical analysis. The article consists of two parts. The first part is devoted to the description, analysis and justification of the design of the wall panel and to the study of the deformed state of the cassette profile and the assessment of the resistance and stiffness of the wall panel based on the calculation method. The second part reflects the results of experimental studies of the panel and its components, and implements a design procedure based on tests.

Rubcon-polymer concrete based on liquid rubber. Due to the high tensile strength of the rubcon, structures made of it are recommended as structures with increased requirements for crack resistance, also should be noted that the value of the ratio of compressive strength to tensile strength lies in the range of 7-8, while in the case of the addition of dispersed reinforcement, this ratio of strength indicators is ~6. For comparison, it should be noted that the ratio of compressive strength to tensile strength for concrete class B25 is almost 15. This indicates the relevance of the use of rubber polymer-concrete as a material for the manufacture of bending elements. The objects of the study are beams of rectangular cross section from the rubber polymer (Rubcon) size 60х120х1400mm. It that the addition of fibers from the steel cord improves the crack resistance of normal section of up to 1.5 times experimentally was established. As a result of the review of literature sources, it was found that the existing methods of calculating the normal sections of bending elements need to be adapted and obtain their own empirical dependences for the calculation of beams from rubber concrete. As a result of the calculation of crack resistance according to the proposed method, the maximum difference of values in the rubcon beams is 5.9%, and in fibrocauton beams, 4.1%.

This article proposes a mathematical model of axisymmetric transverse bending of an annular plate of average thickness, the loading of which is assumed to be on the upper surface of a uniformly distributed transverse load. An orthotropic plate made of a material whose mechanical characteristics nonlinearly depend on the type of stress state is considered. The most universal, constructed in the normalized tensor space of stresses associated with the main axes of anisotropy of the material are taken as the defining relations. The loads were taken in such a way that the deflections of the middle surface of the plate could be considered small compared to its thickness. Plate fasteners are available in two versions: 1) rigid fastening along the outer and inner contours; 2) hinge bearing on the outer and inner contours. Due to the fact that many orthotropic dissimilar materials exhibit a nonlinear stress-strain relationship, the material parameters are taken as functions of the stress intensity. As a result of the formulation of the boundary value problem, a mathematical model was developed for the class of problems in question, implemented as a numerical algorithm integrated into the application package of the MatLAB environment. To solve the system of resolving differential equations of plate bending, we used the method of variable elasticity parameters with a finite-difference approximation of the second order of accuracy.

The relationship between the fundamental frequency of free transverse vibrations ω of multilayer isotropic square plates in an unloaded state and their maximum deflections W ₀ under the action of a uniformly distributed load depending on the number of layers and the rigidity of shear bonds is considered. The number of layers in a composite plate varies from two to ten. In the work, numerical studies of composite two-layer plates on compliant bonds were carried out using the finite element method. A finite element diagram of a multilayer plate is developed. The calculation was performed in the SCAD software package. The curves for different numbers of layers of multilayer plates “Deflection - stiffness of shear bonds” and “Frequency of transverse vibrations - stiffness of shear bonds” are plotted. It is shown that for composite multilayer square-shaped plates, the coefficient K coincides with an accuracy of 5.4% with the same coefficient for square plates of whole section.

The process has been analyzed of monitoring of structure and installation process safety under corrosion hazard of building facilities. A high level of wear and service limits of structures of buildings and installations are the real threat, which increases probability of a loss. The principles are analyzed of assurance of process safety of structures and installations as an integral structural component of the enterprise safety. It is shown that the development of measures of the reliability assurance program comprises the qualimetric monitoring and risk diagnostics of the determining parameters of structural corrosion state. As used here, a methodology is proposed for assessing serviceability of corrosive structures taking into account the requirements of the process approach to quality and safety management based on the principles of DMAIC (Define, Measure, Analyze, Improve and Control). Classified are the signs of serviceability based on the safety class of systems of structure corrosion protection to justify efficiency of measures for structure maintenance based on their actual state. Methods are theoretically and experimentally justified of redundancy of means of primary and secondary corrosion protection of structural steel. A practical example is presented of setting and solving the direct and inverse problems of the design calculation of structure survivability under corrosion hazard.

Emergency cases in buildings are caused by mistakes and imperfections of design documentation, deviations from design documentation and defects of construction. Reinforced concrete structures are the most prevalent type of structures in building and construction. It’s necessary to consider that deformability and crack resistance requirements are the main factors of design of such structures. Correct assessment of deformability and crack resistance depends on physical nonlinearity and creep of concrete and change of bending resistance of a section. The results of the assessment of technical condition of the corrugated concrete slab with significant deflections are given in the article. During the assessment it was determined, that in the course of construction the slab and the beams were built with deviations from design, middle beams had numerous normal and shearing cracks, outside beams had cracks caused by torque and bending moment. Calculations of the slab ender reveal that its strength and deformability are not enough to carry the loadings. Further exploitation of the floor slab will cause its failure. Economical comparison of various types of floor slabs with reference to the given building is done in the article.

The article presents the results of an experimental study of the bending strength of steel-fiber-concrete (SFC) samples after exposure to high temperatures.The properties of SFC based on high-strength cement-sand matrix with reinforcement of five different types of fibers are considered.The percentage of the content of each type of fiber by volume ranged from 0.5 to 6.0%. All types of fibers had different strength and geometric characteristics.The research results showed that the tensile strength in bending of SFC specimens, in the range of exposure to temperatures from 20 to 1100 ° C, depends on the volume content of the fiber and its strength and geometric characteristics. Almost complete destruction of the SFC was observed at a temperature of 1100 ° C for all types of fiber under consideration and at all percentages of reinforcement. The residual strength at this temperature did not exceed 5 MPa.

According to the main provisions of the concept of biosphere compatibility, the feasibility of city functions (in order to increase the level of human potential) can be estimated by the level of accessibility of these functions for each resident. In this work, as one of the groups of indicators that quantitatively reflect the implementation level of the functions of the city, it is proposed to introduce an assessment in the form of a system of quantitative indicators of urban plans. Among these indicators is the time parameter for satisfying the needs of a city resident as one of the parameters for a comfortable and safe urban environment. An integrated approach is used to calculate the indicators of accessibility of objects of daily services for residents as objects that should be located within walking distance. In relation to educational institutions that play a key role in the formation and development of human potential, an analysis of the current urban planning situation is carried out on the example of two territorial entities of the city of Orel. The levels of the city’s functions implementation in providing conditions for preschool education from the position of the territorial location of preschool educational institutions are also determined. The zoning of the territorial formations of the city of Orel is based on a temporary factor. This made it possible to visually assess the level of comfort of the urban territory by the degree of implementation of the considered function of the city and formulate proposals for the development of the network of the objects under consideration.

The study is based on the identified archival and published sources, field research of the author, which enable to reconstruct a more reasonably shaped structure is lost in the nobility and merchant estates in the reconstruction of their spatial organization in the border region of Russia. The scientific novelty of the research is associated with the author's expeditions to identify signs of existence and full-scale examination of a number of preserved manor complexes, which previously did not attract the attention of researchers. Of particular importance is the identification of archival and printed sources that allow more reasonably reconstruct the figurative and material structure of the lost elements of noble and merchant estates. The special significance of the complex research work is due to the possibility to fill the gaps in the study of important pages of the history of national and regional Russian culture, which affected the formation of regional features of construction techniques and imagery of architectural ensembles of the estates of the Kursk region.