Table of contents

This paper is concerned with nonlinear buckling problem of inclined rod subjected to concentrated loads and moments at the ends. Rigorous analysis of geometrically nonlinear structures demands creating mathematical models that accurately include loading and support conditions. This work introduces a new analytical approach to construct the governing equations considering large displacement. The mathematical formulation based on geometrical compatibility, equilibrium of forces and moments and constitutive relations considering large displacements. The geometrical compatibility relationship is getting from integrating along the elastic curve of the deformed rod. A system of nonlinear and integral equations with boundary conditions prescribed at both end is constructed. Using the arc length technique the paper developed incremental-iterative algorithm for solving the system of nonlinear equation. Based on the proposed algorithm, the paper established the calculation procedure and the programs for determining the equilibrium path for generally supported inclined rod subjected to concentrated loads and moments at the end.

In structural engineering, the analysis of plate elements is one of the important problems that based on theory of plates. The analytical solutions using traditional methods and manual calculations are determined in the cases with simple calculation schemes. It will be difficult to solve problems with the complicatedness in loading and boundary conditions. Thereof, the application of numerical methods is necessary to deal with that. The finite difference method and successive approximation method are popular numerical methods to solve relatively thoroughly the plate problems. In addition, with the development of construction technology, the dimensions of the current building projects become greater and lead to increase of building displacements that is required to take into account in analysis. The analysis of plates with non-linear geometrical is relatively complicated and iterative algorithms can help to solve this problem. In this paper, the authors used the difference equations of successive approximation method (MSA) and generalized equations of finite difference method (MFD) to solve the problems of non-linear plates with different boundary conditions and loading. From the comparison of obtained results with Volmir's analytical results the conclusions and recommendations are proposed.

Beams are considered the most popular bending elements used in building structures. With the load-bearing capacity and production characteristics, it is possible to use many different materials to combine them into beams to receive high economic-technical efficiency. Besides, because of the development of structural material industry, the manufacturing and construction technology, the form of beams is as diverse as composite wood beams, foundation beams, force-sensitive composite beams prior to installation grafting, steel-concrete combination beams. So there are many researches about solving the problems of multi-layer structures in general and multi-layer beams in particular by different calculation methods. In this paper, based on the theory of multi-layer composite rods and plates of A.R Rzhanitsyn the solutions of calculation analysis of three-layer beams that is subjected to discontinuous loads using difference equations of successive approximation method (MSA) are presented. The obtained results with good convergence show high accuracy of the numerical method with the use of difference equations of successive approximation method.

The formulas for determining losses in pre-compressed high-strength reinforcement are given, as well as the condition for closing the initial technological cracks in bent elements with pre-compressed reinforcement necessary for calculating reinforced concrete beams with pre-compressed and stretched high-strength reinforcement

The formulas for determining losses in pre-compressed high-strength reinforcement are given, as well as the condition for closing the initial technological cracks in bent elements with pre-compressed reinforcement necessary for calculating the reinforced concrete beams with pre-compressed and stretched high-strength reinforcement

The issue of increasing the building structures steel elements' bearing capacity using the surface plastic deformation (SPD) method, is considered, applying the complex assessment method of the factors' parameters acting on the structure and fatigue resistance, which, in contrast to the current principle of differential evaluation, more accurately takes into account the structure's state in the operating conditions. Interrelated functional dependencies between these indicators are identified and the parametric explanations' systems taking into account the dominance of a certain factor in the design work, are made. These systems of equations make it possible to calculate the interrelated indicators and assess the impact of each of them on the structure's bearing capacity.

Recently, in structural engineering, many main elements in structural systems such as columns or girders are designed with variable cross-section for certain purposes. In addition, in order to determine the appropriate sizes or suitable shapes of structural elements for optimal volume of material under the effect of certain loading or with the given sizes of elements the structures can be subjected maximum loading, it is required to studied the optimization problem. This paper presents the non-linear weight optimization problem of frames with variable section stiffness of columns according to the strength, stiffness and stability criteria with the help of finite element method. The non-linear optimization problem is solved by the Genetic Algorithm. The calculation procedure of non-linear optimization of plane frames with variable section stiffness of columns is established and implemented using Matlab calculation programming software. From the results of numerical examples, the conclusions and recommendations will be proposed.

The limiting elastic state of a beam with large curvature under pure and transverse bending is considered. The gradient plasticity condition which determines the yield onset in an inhomogeneous stress state is applied as a criterion of the ultimate state. The analytical expressions for calculating the corresponding stresses and loads are obtained.

The article is devoted to the use of mechatronic sliding complexes for the construction of high-rise monolithic buildings and tower-type structures made of reinforced concrete. It is shown that high-rise monolithic towers of variable radius, characterized by the increased complexity of technological operations can be erected with high efficiency using automated sliding formwork, which makes it possible to achieve the highest possible pace of construction technology, while ensuring the high quality of work using self-compacting high-strength concrete. A mathematical description of the mechatronic complex as a completely observable multidimensional object with control limitations is given, which allows predicting deviations and deformations of the sliding formwork working platform design during the lifting process, evaluating the internal and external disturbances' effect on the complex's operation, and also modeling the interaction of the lifting and regulating mechanisms in violation of their synchronous operation. It is proposed to use the two-level systems to control the formwork lift and synchronize the movements between the actuators groups. The results of modeling the sliding formwork lifting process are presented.

The article deals with the problem of determining the stress-strain state of a three-layer cylindrical shell with axisymmetric loading, taking into account the creep of the middle layer. The derivation of the resolving equations is given, as well as the solution of the test problem for the construction with polyurethane foam filler. The problem is reduced to a system of two differential equations, which is solved by the finite difference method in combination with the Euler method.

In this article, in a spatial setting, the modeling technique for a reinforced concrete pile immersed in the soil array under the seismic load action has been considered. Modeling of the "pile-soil mass" system elements is performed by the volumetric finite elements. The calculation includes the shock-absorbing properties of the soil mass model ("transparent boundaries"). A comparison of the proposed methodology with the known solutions has been performed. The prospects of further development and practical application of the pile operation proposed model together with the soil under the seismic load action has been given.

This work is devoted to the methodology for calculating the compressed reinforced concrete elements under dynamic loading, which takes into account the lack of adhesion of tensile reinforcement to concrete. As experiments have shown, the lack of adhesion between concrete and reinforcement leads not only to a decrease in the bearing capacity, but also to a qualitative change in the strain diagrams' shape in the sections. The calculations according to the current regulatory documents do not take into account the fact that the reinforcement does not adhere to concrete, as a result, it is difficult to determine the actual bearing capacity of the element. The dynamic impact of loads adds complexity to these types of calculations. This approach makes it possible to perform the calculation in the elastic, elastoplastic and plastic stages of work, while taking into account the absence of reinforcement adhesion with concrete in determining the height of the concrete compressed zone.

The article presents the studies' results on the safety characteristics of the most damaged load-bearing structures in a monolithic reinforced concrete building. Reliability assessment was carried out at the stage of putting the building into operation. The analysis of the numerical reliability characteristics is carried out taking into account design and actually implemented strength parameters of the considered structures.

A simulation of a piezoelectric generator (PEG) of energy is given. A feature of this generator is the presence of two types of piezo elements: plate-type elements experiencing bending deformations and cylindrical-type elements experiencing compression deformations. The simulation in the finite element complex is presented. The results of the analysis of unsteady oscillations during vibrational pulsed excitation of the PEG base are presented. Variations in the time range of PEG loading are considered. The analysis of output power and operation of individual elements of the generator is given.

The article is devoted to the calculation of three-layer shells of rotation with a light filler under the creep conditions. Unlike previous works of the authors, the hypotheses of the theory of shallow shells are not used. General geometric and physical equations are presented, as well as a system of resolving equations for axisymmetrically loaded structures. An example of calculating a spherical dome is given. The features of changes in the stress-strain state of the considered structure during creep are revealed.

Resolving equations are obtained for the finite element analysis of the stability of plates and shells with allowance for nonlinear creep. The issue of plate stability under creep process is investigated by the example of a round plate rigidly clamped along the contour with an initial deflection under the action of radial compressive forces. It has been established that for plates made of a material that obeys the nonlinear Maxwell-Gurevich law, there is a long critical load p_∞. When the load is less than the long critical (p < p∞), the deflection growth rate decays, i.e. buckling does not occur, at p = p∞ the deflection increases at a constant speed, and at p > p_∞, the rate of growth of the deflection increases.

The results of a technical survey of buildings with damage caused by the mutual influence of nearby buildings in the city of Sanaa (Yemen) are presented. The stress-strain state of the foundation is calculated by the finite element method (FEM) using software «Plaxis 3D».

Currently, plates with characteristics of high thermal insulation, sound insulation and strength are sufficiently and widely used in structural engineering. To describing the connect of the plates with other elements, it is possible to give many calculation schemes on the different views. In this paper, it is considered the problem of rectangular plates, each side of which are fixed with hinged support or fixed support. This paper deals with the discontinuous points of boundary conditions with the use generalized equations of finite difference method. The obtained results of the analysis of stress state in discontinuous area of boundary conditions are compared with the results of work of Smirnov V.A.

The article discusses the issues related to the operation of compressed corroded reinforced concrete elements under dynamic (shock) impacts. The experimental data of the samples subjected to flow-accelerated corrosion are presented. Modeling of such samples was carried out by means of the Ansys software package. In this paper we present a static and dynamic calculation of the experimental samples in the Ansys software package.

The breaking load comparison of the samples obtained during the experimental tests and in the Ansys software package, which has fairly good convergence, is made. The comparison of the experimental and obtained as a result of calculation in Ansys diagrams of the corroded-damaged reinforced concrete element and tensile reinforcement concrete compressed zone deformation is presented. The values of dynamic hardening coefficient were obtained for the first time depending on the corrosion damage section's length.

The forced transverse vibrations of constant cross section beams taking into account damping are studied. Nonperiodic, periodic, and harmonic beam vibrations from vector disturbances are considered.

The article proposes a solution to the stability problem of a revolving bar loaded with axial force and inserted into a rigid pipe with a gap by the Bubnov-Galerkin method. Two options as the deflection coordinate functions are considered. When calculating, the dead weight of the bar is taken into account. With a total load greater than the Euler load, lateral forces (reactions), touching the pipe wall, appear in the bar. At the end of the article, the formulas for determining the voltage after buckling are presented. The obtained formulas make it possible to determine the critical load of the system for each individual case, taking into account its dead weight and centrifugal forces from the revolving bar. The above-mentioned relations also give an opportunity to determine the reactive moment magnitude from the contact of the revolving bar and the pipe wall.

Real earthquake records differ from each other in a number of spectral parameters, the main one of which is the prevailing oscillations period. It usually varies over a wide range.

This work is devoted to the study of the seismic isolation systems' sensitivity with a sliding foundation belt, kinematic supports and rubber-metal supports to the prevailing period of strong seismic impact. The studies were conducted on the example of a 5-story building with a rigid structural solution with seismic isolation in the foundation part. Seismic impact is presented as a synthesized accelerogram. The main attention is paid to the maximum movement of the building at the seismic isolating supports' top level, which in reality is limited based on the supports stability and (or) the utility networks safety in the building. The seismic reaction dynamic calculations' results of the systems under consideration are presented. It is shown that seismic isolation systems with an increase in the predominant period of seismic impact of 9-point intensity lose their advantage and the maximum displacement of the building with long-period influences becomes unacceptably large).

An effective version of the energy method is recommended when calculating the rectangular cantilever strips for stability of a flat bending shape taking into account its own weight. The essence of this method's variant is to use the Lagrange variational principle instead of the condition for the potential strain energy equality and the external forces work. The proposed approach makes it possible to perform the calculations' machine implementation and take into account an arbitrary number of the series members. The solution to the problem for the cantilever beam is presented taking into account its own weight and the concentrated force action.

The article discusses the BIM competencies and their components in the preparation of highly qualified personnel in the construction field. It is imperative that educational institutions fully teach the students digital technologies and BIM competencies. The analysis carried out in this article shows that the students and graduates are poorly oriented in the rapid change of the construction industry. The developed course "Computer-Aided Design and Calculation of Building Structures" and methodological recommendations, with step-by-step instructions and the content of connected tools, show a positive trend. As a result, professional schools will be able to prepare the graduates with sufficient knowledge and skills to work with modern BIM tools.

A method for approximating the aperiodic characteristics class in the category of exponential polynomials has been developed. The advantage of this technique is that even though there is no strict regulation on these polynomials' structure, it is possible to achieve adequacy with a smaller number of approximating summands and to include the additional systemic information on the technical object (technological process) to the model.

The arrivals of high intensity seismic Rayleigh and Rayleigh – Lamb waves to the buildings and structures with a relatively large footprint are analysed. The most frequent cases of the foundation structures' fracture and damage are discussed. The methods for seismic protection from the main types of surface seismic waves, Rayleigh, Rayleigh – Lamb, Love and some more peculiar evanescent (head) waves are considered. The analytical and numerical methods for modelling interaction of building structures with these types of surface seismic waves are analysed. The comparative analysis of the wave dynamic method and the methods based on the spectral decomposition is given.

The causes leading to the technological equipment contamination of for rolling mills and consequently the environment are analyzed. The prospects of using the magnetic separators are substantiated. In order to reduce water consumption to a minimum by rolling production and to reduce the emissions of scale with oil products on its surface into a water body by ten times, high-quality treatment of reversed waterby permanent magnet separators with a fineness of 1–2 mkm is required. The mathematical modeling methods of the quality characteristics separation for monodisperse and polydisperse aqueous ferromagnetic suspensions are considered. It is shown that the required refinement can be achieved in multi-row magnetic separators.

The causes and modes of stable and reliable functioning of magnetic separators based on the developed mathematical theory of magnetic deposition process for ferromagnetic particles on the surface of magnetic rods in an aqueous suspension stream are revealed. The limiting thicknesses of the ferro-sludge layers deposited on the surface of the magnetic system, the threshold flow rates of aqueous technological fluids, the criterion conditions for the ferroparticles deposition and the zone of the working region responsible for the magnetic coagulation process in magnetic separators are determined. The correct method for assessing the stability of the cleaning characteristics of the magnetic separators with a scatter of the ferroparticles' initial parameters, the permanent magnets and dynamic viscosity of the process fluid has been depicted.

The magnetic coagulation process mechanism features occurring in magnetic separators are disclosed. Magnetic coagulation occurs only at the threshold concentrations of ferro-particles in aqueous ferromagnetic suspensions. The basis of convergence (aggregation) mechanism of ferro-particles in a gradient external field is the difference in the ferro-particles' speed with different masses. Based on mathematical modeling, it was found that during coagulation, the residual concentrations of ferro-impurities cannot exceed certain limit values, and mathematical expressions are obtained for calculating the distributions of the dispersed composition of aggregated particles. The combination of optimization procedures for the magnetic separators' geometric parameters and the cleaning characteristics taking into account magnetic coagulation makes it possible to ensure the high levels of cleaning efficiency of finely dispersed ferromagnetic suspensions while reducing the cost of magnetic separators up to two times at the design stage.

The study examines the influence of the docking nodes reinforcement geometric, mechanical and structural parameters on the stress-strain state of the overhead power lines supports structure taking into account the supports concreted base interaction with the surrounding soil. The steel supports of the overhead power lines, which are thin-walled shell-rods of a closed profile, are modeled by the finite elements of the Tymoshenko-type shell. The concrete base of the support and the surrounding soil are sampled by three-dimensional finite elements of a continuous medium with the corresponding physical and mechanical properties. The influence of the kinematic conditions options for securing the support and taking into account the contact interaction of the concrete support and soil on the VAT design calculation is studied. A methodology for calculating the structures of steel supports and their docking catches was implemented as a part of the ANSYS 14.5 numerical simulation software package. Based on the proposed methodology, a computational experiment was conducted, during which the analysis of the stress-strain state of the overhead power transmission towers fixed in the ground for various types of the docking nodes reinforcement.

Pipe concrete as a complex material, which effectively combines the advantages of steel and concrete, is used in the construction of high-rise and long-span structures and has good prospects for expanding the scope. At present, this is prevented by the relatively poor knowledge of the steel shell interaction with the concrete core under operational loads, when, due to the difference in the coefficients of transverse deformation of steel and concrete, the shell can detach from the core and lose its stirrup effect, which significantly increases the concrete strength. In the article in a linear-elastic formulation, the Lame problem is applied to a circular cylinder subjected to internal (for the shell) and external (for the core) uniform radial pressure, as well as an external centrally applied the longitudinal compressive force. The formulas for determining the stresses and radial displacements in the shell wall and core are obtained. The recommendations on providing the conditions for the joint operation of the shell and core, which are relevant, in particular, for the pipe-concrete kinematic racks of foundations protecting the buildings under seismic effects, are given.

The aim of the work was to conduct a comparative analysis of the static work of two structural types of steel poles of power lines (HVPC): in the form of a closed profile rods-shells with height-varying wall thickness and in the form of a trellised trihedral design made according to the patent [1]. In this case, both types of supports were considered for three different heights-under power lines of 10 kV - 9-11 m high, 35 kV - 20.6 m high and 110 kV - 22.5 m high, respectively. The bulk of the research was carried out at the ANSYS PC, where the joint work of the structural system "steel support of an overhead power transmission cable - a prefabricated and dismantled reinforced concrete foundation of a new type [2] - soil base" was considered. For this, the authors proposed a computer simulation technique that takes into account the spatial work of the structural system elements and the physical nonlinearity of the materials they are made of. At the same time, the Mises strength theory was used for steel, Williams-Warnake yield criterion was used for concrete, and Drucker-Prager yield criterion was used for the base soil. In addition, all the necessary geometric, power, and physical characteristics of the model were obtained on the basis of the current building codes for the energy facilities' design. The auxiliary engineering calculations taking into account these codes were performed in the LIRA-SAPR 2017 PC in a linear formulation.

It is known that multi-hollow panels for simplification in the calculations are presented in the form of I-beams (T-shaped) beams and are considered according to the beam theory. The material for such structures is reinforced concrete - a composite material that combines the mutual work of concrete and steel reinforcement. The purpose of this work is to study how the cross-sectional representation shape of the multi-hollow panels made of the reinforced concrete structural material affects the samples of various lengths, by establishing the action of the above factors (the way the cross-section and length are represented) on the bearing and deformation ability, as well as the cracking load. We examined the various length panels' samples, freely supported and working on bending, with a cross section in a natural form, in comparison with the similar length I-beam samples. The load was sequentially applied to the samples in increments of 1 kN, until the yield strength of the reinforcement in the stretched zone was reached. A numerical study of multi-hollow panels was carried out, taking into account the physical nonlinearity of reinforced concrete, with the formation of a plastic hinge in the middle of the span. The load-deflection graphs are obtained when modeling the corresponding lengths of the samples with a natural and I-section shape. It was found that the length of the panel affects the calculation results of the shapes under consideration, and the shorter the length, the more obvious the deviation in the load-deflection graphs. The correction factors to refine the calculations of reinforced concrete slabs for cracking, deformation and breaking loads are proposed.

The distribution laws' composition of the permanent, long-term temporary, snow and wind loads acting on the structure of buildings and structures is estimated. The following load distribution laws are respectively adopted: normal, logarithmically normal, Gumbel and Weibull. The calculation of the four main central statistical moments was carried out, the approximate distribution law for the generalized load was established by the expansion method in a Gram-Charlier series, as well as the magnitude of its statistical variability. The characteristics of the load variability are compared with the approximate solution of A.N. Dobromyslov. The results obtained are intended for the practical solution of the problems of assessing the safety and residual life of buildings and structures using the reliability theory methods.

The complex assessments of the main jointly acting and heterogeneous factors (geometric parameters, stress concentration, surface hardening and compressive stresses) on the building structures elements and units' fatigue resistance, which in early studies were taken into account in a differential way, are considered. In this paper, for the factors' complex assessments, the method of prioritizing the choice of one of them, which is dictated by the requirements for building structures (design, technological, operational, technical maintenance, repair and restoration), is adopted. As a priority factor, in particular, the technology of surface hardening is considered, the use of which significantly increases the structural elements' bearing capacity and allows the application of relatively cheap low - and medium-carbon structural steels as the main material. Using the method of system analysis, the classification and grouping of the parameters of these factors and fatigue resistance indicators was performed and their database was created. The statistical data processing was performed and the regression equations between the specified parameters and indicators were obtained. Using the principle of the priority of factors, systems, the obtained equations for applying the interrelated values of these indicators in calculations for the bearing capacity of structural elements are formed. Using the equations of the obtained systems in I...IV quadrants using the grid (x,y), considering the logical sequence of determining the fatigue resistance and the priority influencing factor's principle, by means of the nomogram method three nomograms are composed, with the priority to the factors considered, which allow to determine the whole complex of these indicators promptly and taking into consideration the production environment by the simple graphical constructions means.

The issues of increasing the bearing capacity and fatigue resistance of structural building elements, working surfaces and edge transition sections affected by the surface plastic deformation, are considered. The regression relationships between the influencing factors' parameters and fatigue resistance coefficients are revealed. Taking into account their relationship, the multiparametric functional relationships and systems of equations are compiled making possible to determine the optimal values of the remaining parameters in the case of the priority factor proposed parameter's (coefficient) presence.

The unsteady thermoelastic problem of the rock mass stress state in the vicinity of a spherical cavity in the temperature field presence is considered. The temperature field around the cavity, partially filled with coolant, is calculated by the explicit difference scheme. Such tasks arise during the creation and operation of the underground cavities for the various products' long-term storage. Moreover, the tendency to self-heating of the stored substances leads to the appearance of high-temperature fields, which in turn can cause the significant temperature stresses' occurrence. A feature of the work is to take into account the two-dimensional heterogeneity of the massif material, which is due to both the fracture of the rock and the dependence of the deformation characteristics on temperature. In the article, the problem of thermo-elasticity is solved as quasi-stationary. Obtaining analytical solutions in the problems of thermo-elasticity of inhomogeneous bodies is associated with great difficulties. Such solutions are obtained, as a rule, for the case of one-dimensional heterogeneity of an object's material. The obtained temperature field was used to solve the problem of determining the stress state of the array, and the finite element method was used. The results obtained indicate the need for calculations and design of underground cavities to take into account the real properties of the rock mass materials, as well as their change under the influence of various physical processes.

The results of a numerical experiment in the framework of a theoretical study of the strength and crack resistance of the reinforced concrete beams available or non-available in fiber reinforcement are presented. The fiber reinforcement presence influence on the strength and crack resistance of the reinforced concrete beams' normal sections is determined by varying the following parameters: working reinforcement class; percentage of reinforcement with steel reinforcement; the presence and degree of the reinforced zone reinforcement prestressing; the presence or absence of the beam compressed zone reinforcement; the steel fiber reinforcement presence. Reinforcement of concrete with steel fiber had a significant impact on the theoretical strength and crack resistance of the reinforced concrete elements' normal sections, both in the presence and in the absence of the working reinforcement prestressing. The calculation showed that in some cases the presence of fiber reinforcement will eliminate the prestressing of the working reinforcement or significantly reduce its level, abandon the reinforcement in the compressed zone and, under the certain conditions, replace the high-strength prestressed reinforcement A600 with the reinforcement A400 without increasing the total consumption of steel by the sample.

A computational scheme for the optimal design of steel flat frames made of thin-walled rods with closed cross sections has been developed. The structural elements' total cost is minimized by searching for the materials' grades and the rods' cross sections sizes on the variable parameters' discrete sets. The rods are separately grouped according to the condition of using one steel grade and the criterion for the cross sections' identity. Active restrictions on the overall structural system's stability, local stability of the rods' walls, strength and stiffness are taken into account. The optimization process using a genetic algorithm using a mixed approach to the mutation procedure, a selection option that provides the inoperative design options, and a single-point crossing-over procedure for the simple exclusions from consideration is implemented. The deformable object stress-strain state analysis is carried out on the rod finite element model's basis. The assessment of ensuring overall stability is carried out by checking the positive definiteness of the tangent stiffness matrix of a finite element system. Local stability using an analytical relationship for rectangular plates, generally subjected to compression-tension and bending in their plane is confirmed. The results of optimization of a three-span frame made of square pipes are presented. Steel grades and profiles were selected for the groups of the structural system's rods.

The results of the cracking and fracture process investigations in the inclined sections of the reinforced concrete beams, in the conditions of reinforcement presence or absence in the supporting areas with the triangular U-shaped carbon fiber clamps, are presented. The impact of a slice span of 1.5h0, 2.0h0 and 2.5h0 is estimated, as well as the presence of composite reinforcement, on the inclined cracks' formation and development features.

The materials use in structures and calculations for buildings and structures in Russia is determined, inter alia, by the normative loads of snow cover on the construction site. An urgent task is to determine its significance for the unexplored areas. The results of determining the normative value of the snow cover weight and changes with the height of the snow weight terrain for the designed objects of the "Udokan" Mining and Metallurgical Combine at the altitudes from 600 to 2000 m are presented. To determine the estimated snow load on buildings and structures in the territory of the facility creation, we used the series of the water supply annual maximums in the snow cover obtained as a result of the snow-measuring route observations at high-altitude weather stations located close to the designed objects. Based on the data of weather stations, a regression linear model of the water supply dependence in the snow cover on the height above the sea level was built. The main calculation method for finding the coefficients of a linear equation is the least squares method. It was revealed that with an increase in the height above the sea level by 1 m, the water supply in the snow cover increases by about 0.1 mm.

The materials and construction of buildings and structures used should be linked to the number of lightning strikes per year. Lightning protection of buildings and structures should be based on the parameters of thunderstorms in the territory of the project design. Thunderstorm is one of the most dangerous meteorological phenomena. Both ground objects and aircrafts are affected by thunderstorm activity: airplanes and rockets. The main objective of this work is a comparative assessment of the buildings and structures impact by lightning, depending on the methodology for determining the thunderstorms duration in hours for the territories in the North Caucasus. The analysis on the basis of data from the thunderstorm direction finding net (TDFN) of the FSI "VGI" and data from weather stations has been performed. To solve this problem, a study on the relationship between the number of days with a thunderstorm and the duration of thunderstorms in hours for the territories in the North Caucasus has been performed on the FSI "VGI" (TDFN) data basis. In order to determine the above-mentioned statistical characteristics of thunderstorms and their variations in the North Caucasus, for the first time in Russia, the LS 8000 lightning recorder manufactured by "Vaisala" Finland was used.

The paper considers the interaction of contact friction forces in the system "base - inclined foundation - holding structure" and their influence on the stress-strain state of the soil base in the zone of the foundation structure's adjacency to the holding structure. The main features of the contact friction forces' distribution, the places of their application and the calculation algorithm are determined. The design scheme of the inclined foundation is developed taking into account the occurrence of a generalized total friction force. Based on the obtained dependences, the additions and refinements to the existing methodology for calculating foundations on an inclined soil base using a variable stiffness coefficient have been made.

Ensuring the increased requirements for heat saving, environmental safety and comfort of residential and public buildings is one of the main directions of scientific and technological progress in construction. In particular, the cellular concrete products' use in building envelopes is aimed at solving these problems. Cellular concrete blocks perform the wall-forming material functions and insulation simultaneously due to their thermophysical and strength characteristics. However, the factor reducing the energy efficiency of aerated concrete masonry is the filling of masonry joints with adhesive or cement-sand mortar, which are the thermometer bridges, and the use of polyurethane adhesive, which has lower thermal conductivity compared to adhesive mixtures, as an aggregate of vertical and horizontal joints is unacceptable due to its high deformability and low shear stiffness. The authors examined the systems of building envelopes made of cellular concrete blocks used in civil engineering, and identified their shortcomings that affect the energy efficiency of the entire building. The authors have developed an energy-efficient two-row masonry of cellular concrete blocks, the device of which allows to reduce the masonry thickness and facilitate the installation of the enclosing structure with equal masonry thermal conductivity.

Polymeric materials, in particular reinforced coatings, are widely used for the repair of worn and damaged plate building components of various types. Coatings made of polymeric materials not only increase the plate components' thickness and smooth out the surface roughness, but also provide a reduction in stresses in the region of existing holes or perforations. The article presents a calculation technique that allows to increase the accuracy and reliability of determining the ability of coatings made of polymer materials to reduce stress concentration. Mathematical models for determining the stress state parameters of a plate building component with holes covered with a polymer material are obtained. The calculations confirmed that the use of polymeric materials as a coating reduces the normal and tangential stresses arising at the edge of the hole.

The article presents the strength study results of the tuffcrete flexible monolithic structures with fixed formwork, combined reinforced rods and fibers. The nature and degree of the fibers percentage influence in the tuffcrete element of the fixed formwork, the dimensions of the fixed formwork elements' fiber-reinforced section and the strength of monolithic tuffcrete on the normal strength to the longitudinal axis of the monolithic combined-reinforced bending floor structures, as well as on the adhesion strength of the fixed form contact line with concrete monolithic, are analyzed. The experimental dependences that make it possible to more economically design the structures under consideration, taking into account the strength and quantity parameters, as well as the geometric dimensions of their individual components, are proposed.

The seismic activity assessment on the territory of the Republic of Crimea and in adjacent areas in 2008-2018 was performed. As the main materials for the study, the literary data on seismic activity on the territory of the Republic of Crimea and in adjacent areas for the period 2008-2018 were used. The collected materials were generalized and systematized by the authors from a unified methodological position, which allowed a reliable enough estimate of the space-time division of earthquakes in the studied region. The seismic events' activity on the territory of the Crimean-Black Sea region in the period 2008-2018 is analyzed. On average, about 95 earthquakes annually occurred in the region during this period. The results of a comparative analysis of the earthquakes distribution in the region areas are presented. It is shown that most of the seismic events were recorded in the Yalta and Kerch-Anapa regions. Quite a lot of seismic activity was also observed in Alushta. The largest number of earthquakes occurred with the energy class к_r =6-8 (73,5%), to the seismic events share with к_r =10-13 accounted for 6.3%. In 2009 and 2014 an increase in seismic events with an energy class к_r =5 was noted. The presence of any stable trend in the quantity and energy class of earthquakes that occurred during the studied period of time was not detected. The analysis made it possible to evaluate seismic activity in the territory of the Republic of Crimea and in adjacent areas for 2009-2018 and show the temporary changes that occurred in the number of recorded earthquakes, their distribution by the region and energy class.

The article is devoted to technical support of engineering surveys and design during the structures' construction. Technical support aims to develop and implement the new research methods to obtain the most accurate and reliable data. The author considers the tower of NSC JSC as an example for the possibility of installing the additional equipment for the BS 66487 "New Dzheguta" base station. The design indicators' determination was carried out using the Selena computer program, which made it possible to get the structure's actual performance in a short time, excluding the fairly old methods of examining the construction sites, to facilitate the work and reduce the time spent on diagnosis at the same time.

The study of the rectangular cross section beam's stress state, weakened by round drillings has been performed. The results' reliability is confirmed by calculation in the LIRA SAPR and ANSYS Mechanical APDL software packages. The results have been compared with the solution by the materials resistance methods.

In difficult engineering and geological conditions, the water-supporting elevated structure's design is carried out taking into account the base soil model, as well as the correctly selected software package, which allows to determine the stress-strain state (SSS) of the structure and as a result, all structural and technological parameters qualitatively.

Taking into account the nonlinearity of the structures base soil work of the of the of during geotechnical calculation makes it possible to adequately determine the stress-strain state (SSS) of structural elements and, in general, the base - foundation - structure system.

Taking into account the nonlinearity of the soil during geotechnical calculation, including modeling the base stiffness, makes it possible to correctly determine the structures' stress-strain state (SSS), as well as to consider their work in the base – foundation – structure system.

Damage to individual structures or their elements at water structures can lead to irreversible consequences with significant damage and tragedies. The influence assessment degree of the plastic deformations, local subsidence of soil on the structure performance is an urgent task that requires attention.

Identifying the type of damage in which the structure's performance is not ensured is one of the most critical tasks in assessing the structures' performance. The necessity of assessing the structure's behavior for operability in the base - foundation - elevated system is proved.

The base modeling using the elastic-ideal-plastic Mora-Coulomb model made it possible to evaluate the vertical displacements in the presence and absence of local subsidence. It was established that the influence of local sagging in the second and third zones does not significantly affect the vertical displacements recorded on the pile grillage's surface.

Based on the numerical simulation of the structure, a decrease in the frequency was revealed with an increase in the number of defective sections. A change in the deformed oscillation pattern at the corresponding frequencies is observed. The method clearly makes it possible to increase the hydraulic structures' efficiency.

Establishing the category of a hydraulic structure's technical condition is an urgent task that constantly requires solutions during operation. Both the operating costs and the safe operation will largely depend on the choice of a survey method and its reliability and validity. The method of structural dynamic diagnostics, which is becoming more widespread, is promising and relevant, however, based on the relative novelty of the method, its application requires closer attention, including consideration from the standpoint of numerical modeling.

Free compressed beam transverse vibrations of a variable cross section carrying a distributed mass are considered. The mathematical model of oscillations is presented as a boundary value problem from the basic partial differential equation of the fourth order hyperbolic type in spatial coordinate, the second order in time and boundary conditions. The technical theory of the rods' bending vibrations, based on the Bernoulli hypothesis about the invariance of flat beam cross-sections, has been used. The task is to determine the eigenvalues, eigenmodes of oscillation and the attenuation coefficient (extended Sturm-Liouville problem). It has been argued that solving the problem by the analytical methods is impractical due to the large transformations and calculations volume. The variables separation methods, finite differences and computer technology have been used. An algorithm for solving the problem, implemented in the Matlab software environment in the form of high-precision graphical and analytical calculations, has been developed. On a concrete example of a beam, verification of the proposed mathematical model has been demonstrated. The practical conclusions have been made.

The forced transverse oscillations of the variable cross section compressed beams under seismic and technogenic impacts are considered. The source of oscillations is the kinematic perturbations of the beam ends in the form of a harmonic or random vector process. The mathematical model of oscillations is presented as a boundary value problem from the basic partial differential equation of the fourth order hyperbolic type in spatial coordinate and the second order in time, which is supplemented by the boundary conditions. The beam fluctuations are interpreted as the spatiotemporal random fields inhomogeneous in space and stationery in time. In the deterministic case, the amplitudes of the forced oscillations are determined, the influence of the kinematic disturbances' frequency and the beam oscillations' shift of their phases is studied. In the stochastic problem, the standard deviations for the deflections are calculated, the influence of the characteristic frequency and correlation of the components of the vector perturbation process on the deflections' output function is studied. The problem is solved by the methods of the variables' separation, finite differences and the theory of random processes. The examples are considered, the conclusions are drawn from the calculations results in the Matlab computing complex environment.

The experimental-theoretical studies' results on the work of two-layer combined reinforced elements with pure bending are presented. The full-scale tests of single-layer and two-layer elements with combined reinforcement showed that the vermiculite-concrete layer increases stiffness and crack resistance by 15–20%. The proposed numerical method for calculating the bilayer elements on bending forces provides high convergence (95%) with the full-scale experiments' results.

The results of the two-layer reinforced cement shells' bearing strength parametric study under the temperature and power effects of a standard fire are presented. The influence and the magnitude dependence plots of the power load, concrete class and the thickness of the shell layers on the structure's bearing strength are revealed. The optimal thicknesses of the structural and protective layers of the shell, as well as the cement-cement layer concrete grade, are determined.

The presence of cutouts in the beams' walls made of steel or from modern composite materials reduces their shear stiffness and increases deflections in comparison with beams of the same size with a solid wall. In this paper, we study the deflections of perforated beams with a sinusoidal shape of cutouts, which are widely used in construction recently. The cutouts' effect on the perforated beams' transverse bending was investigated analytically using the theory of composite bars and the finite element method. The aim of this work was to obtain an analytical dependence that allows to reliably evaluate the deformations of the beams with hexagonal cutouts with different angles of rounding. The study was conducted for the beams of different sizes, made by the non-waste technology from a rolling profile. An analysis of the calculating results for the beams made of different materials showed that with a decrease in the material elasticity modulus, the deflections of the beams increase, and a change in the yield strength of the material does not affect the deformation characteristics. The obtained dependence is applicable for the beams with a relative length l/H ≥ 10 at a relative cutouts' height h / H = 0.667 The discrepancies with FEM results do not exceed 1.5-3%.

The article solves the problem of the stress state of a heavy half-plane, weakened by a semicircular recess (modeling a foundation pit) and under the influence of a uniformly distributed load (modeling weight from a nearby building). The solution was obtained in a closed form. Visual calculations results in the form of diagrams and isolines of the total voltage are presented. The resulting solution made it possible to consider two practical problems. In the first statement, to assess the pit parameters' influence on the components of the additional voltage in the corner zone of the distributed load. In the second statement, to assess the distance influence from the pit to the load on the additional voltage components. The analysis of the obtained solutions is carried out. The quantitative character of the change in the additional stress components, on which the dimensions of the influence zone of the construction pit and the existing buildings foundations' deformation is of particular practical interest.

The experimental studies' results of the foundations with a soil base interaction are presented. The relevance of the research is associated with increased accidents of buildings and structures in recent decades. The reasons for the occurrence and features of sudden foundations loading are considered. The experimental research methodology, the characteristic models of foundations are presented. The preliminary experimental studies' results of the foundations with sudden loading are presented and analyzed. Some features of the "foundation-soil" system are determined. A decrease in the bearing capacity of the foundations during sudden loading, depending on the level and prestressing type, was revealed. It is established that the main reason for the decrease in the foundations' bearing capacity is a change in the normal contact stresses diagram. The necessity and directions of further research in this area are substantiated.

The article presents the experimental studies' results on the subsidence soils reinforcement percentage influence during cementation on the deformation characteristics of a soil base after fixing. A nonlinear dependence of the fixed soil deformation modulus on the reinforcement percentage and the initial (natural) deformation modulus is established. High convergence of the obtained theoretical and experimental data is proved.

The fractal structures paradigm is applicable for creating the complex architectural objects. Using special programs, it is possible to implement a comprehensive model of the fractal architecture building as a structure consisting of an endostructure and an exostructure. During the study, the first two iterations of the endostructure on the possibility of using such structures' element as a supporting skeleton of a fractal architecture building were considered. The endostructure elements of the first iteration strengthen the exobase and the lower surface of the f-quarks of the exostructure. The endostructure of the second iteration is much more complex and voluminous than the structure of the first iteration and strengthens the upper part of the exostructure. To ensure the stability of the fractal architecture building, the framework is formed by connecting the elements of the endostructures of the first and second iteration. Based on the fractal structures' formation analysis results, the unique building stiffness cores formed from the f-quarks exobase have been developed. The strength and rigidity of the building is ensured by the combined action of the endostructure's elements, the exostructure's elements and the developed stiffness cores. Comprehensive building model was implemented in ANSYS PC. According to the numerical experiments' results, the maximum displacements, shapes and frequencies of the fractal architecture object's natural vibrations are determined. The proposed design solutions for a complex model of a building based on a fractal structure are unique and require the use of innovative technologies and materials.

The paper considers the reinforced concrete structures' reinforcement of an administrative industrial amenity building facility that received damage during their operation. The main results of the technical survey of the facility are described with a description of the structural damages' possible causes. The proposed atypical reinforcement of the load-bearing structures contains the changes in some design solutions in two versions, which ensure the facility's further safe operation. Based on the performed analytical calculation, the design solutions to restore local damage and deformation, as well as to ensure the overall spatial rigidity of the structure have been developed. The technology for performing restoration work is described in detail.

Pipe-concrete structures are effectively used in the high-rise and long-span structures' construction. This complex material has the properties that distinguish them from the conventional metal and reinforced concrete structures. However, the wider use of pipe concrete in construction, despite a large number of studies, is constrained by the lack of documents governing the calculation, design, production process technology and rather significant discrepancies in the experimental data of various authors on determining the interaction forces of the concrete element's case and core. This is explained by the influence on their size: the method of applying the load (axial or with eccentricity, to the entire cross section or only to the core), its action duration, the ratio of the wall thickness to the cross section size, deformability and strength of concrete, the ratio of steel and concrete amount in the cross section. In this paper, based on the solution of the Lame problem for a circular cylinder, we obtain the formulas for the interaction forces between the core and the case, taking into account various factors. The yield strength of the case steel and the ultimate deformation of the concrete core are accepted as the criteria for the structure's strength. Axial compression is considered without loss of shape stability, i.e. with a structure length not exceeding the five cross-sectional diameters, which usually corresponds to the length of columns in civil buildings.

The article presents a methodology for determining the stress-strain state and breaking load for concrete filled steel tubular columns in a physically non-linear setting. The calculation is performed step by step, for each step in the load, the problem is reduced to a system of three linear algebraic equations. The results are compared with known analytical dependences, as well as with the results of calculations in a three-dimensional formulation using the finite element method.

The problem of the building structures' optimization is considered in architectural bionic modeling on the bionic principles' basis. The architects realize that the plastic of buildings can be completely arbitrary, but nature provides them with the best solutions. For this, it is necessary to study the structural laws of natural objects and use the ideas for both the structural elements and the entire structure when designing. For the further use of various materials in construction, it is necessary to take into account the variety of architectural solutions. Bionics makes it possible to find the most unusual in form and optimal in structure designs for the design of a wide variety of structures.

The article presents a draft program of a comprehensive construction and technical examination of the industrial building structures. The features of the construction and technical examination of the industrial building structures are described. An algorithm of the sequence of actions for the technical examination of the object structures is developed. The measures to repair and restore the working condition of the damaged structures have been developed.

The article presents the results of the scientific studies of the plasticity / rigidity of thinking among the bachelors of the Academy of Architecture and Arts, receiving training in the specialties: architecture, design of the architectural environment. In the field of modern architectural design, there is a process of reanimating the importance of hand-made graphics as an indispensable component of professional competence, which cannot but affect the content of training programs in training the specialists in this field. The author proves the hypothesis that there is a relationship between the abilities of students to use manual graphics in the design of projects with such a property of thinking as creative flexibility. The deliberate development of this ability through the educational tools will optimize the students' assimilation of basic professional competencies in the field of architecture and design, increase the competitiveness of a university graduate.

The relevance of the work is due to the need to study the regeneration experience in the objects of regional culture and the need to study the methods of ethnodesign in measures to preserve the historical and cultural heritage that can create a new type of ethnocultural landscape of the 21st century. The purpose of the work is the study of various methods and techniques of modern ethnodesign in building an ethnocultural pattern, proposing the specifics of its traditional morphogenesis. The work uses the methods of historical and cultural analysis, methods of comparative analysis. The result of the study is to identify the most effective methods of ethnodesign in the regional culture objects regeneration complex measures, as well as the influence of the interaction summarizing effect of the applied techniques for the project's successful implementation - the effect of which significantly exceeds the effect of each separately applied technique. The result of the study is the disclosure of the complex method mechanisms of reconstructing the historical ensemble of an ethnographic settlement – the problems are not solved by the targeted measures to preserve and restore individual objects, but in a complex of historical buildings and cultural landscape. The studies have shown the important role of deep study and comprehension of oral and written sources in the process of creating the ethnodesign objects that have authenticity and the ability to model the spiritual culture.

The purpose of the article is to consider and analyze the stylistic features of neoclassicism, manifested in the architecture of the Lower Don cities in the early twentieth century. To achieve this goal, literary sources were studied and a visual analysis of the architectural objects of the period under consideration was carried out. The article describes the factors that influenced the formation of neoclassical trends in the Don region in connection with the general dynamics of the architectural development and the peculiarities of its socio-economic and cultural situation at the time. The interrelation of various conditions that affect the choice of options for volumetric, spatial and artistic solutions of architectural monuments of the first two decades of the twentieth century is analyzed depending on their purpose and the general urban situation. The analysis of the used stylistic means and plastic features of the Don region the most significant architectural structures appearance related to pre-revolutionary neoclassicism was carried out. In the final part of the article, the conclusions regarding the regional architecture neoclassical monuments' features in comparison with the capital's architectural structures of this period are drawn. In particular, it is noted that, unlike many metropolitan architectural designs, in the buildings built during this period in the cities of the Don Territory, a mixture of stylistic means is often observed due to the regional specifics. The modern look of the Don region cities (primarily their historical part) is largely determined by the neoclassical architecture monuments, and the consideration of their features is necessary when developing the new architectural solutions designed to ensure the comfort for the urban environment.

The article discusses the features of decorating the surface of walls in wood-frame housing construction, taking into account its features, improving technologies and the interchangeability of materials and structures. The importance of low-rise construction in Russia in the context of government decisions is indicated. It analyzes the current state of the finishing materials' range for wall decoration and their evolution. The formulations of binders, soils and methods of their application are given.