The article presents the approbation of the previously proposed algorithm for calculating flat rod systems whose cross sections have one axis of symmetry and the material is physically nonlinear. The diagram of the relationship between stresses and strains corresponds to an ideal elastoplastic material or an elastoplastic material with hardening. The calculation algorithm is based on the developed finite element of the mixed method. Examples of calculating statically determinable rod systems are given.

Keywords: finite element of the mixed method, elastoplastic material, physical nonlinearity

When forming in the process of centrifugation an annular section by the method of ""separate"" concreting with the formation of a section of the product at the first stage from the original, including fine-grained concrete mixture, and with the introduction of a coarse aggregate at the second stage into the formed circular section, followed by the final formation of the section and compaction of the concrete mixture by centrifugation, the speed, calculated for the compaction stage, increases, depending on the section zone, the concrete compressive strength from 20% up to 47%, the initial modulus of elasticity from 6 to 19% relative to single-stage centrifugation. The ratio vint / vext of ultrasonic pulse velocities for surface sounding along the inner (vint) and outer (vext) faces of a centrifuged annular section can be considered as a conditional indicator of the uniformity of the concrete structure over the cross section of a centrifuged product. Key words: centrifugation, separate concreting, structure homogeneity, strength and deformation properties, porosity.

Keywords: centrifugation, separate concreting, uniformity of structure, strength and deformation properties, porosity

The strength, deformability and width of the opening of normal cracks of prototypes 220, section 12.5x25 (h) cm, reinforced with composite canvases and laminates of different cross-sectional areas, made on the basis of glass and carbon plastics, are compared. The samples had working reinforcement, represented by 2Ø14А600, transverse - with double-section clamps Ø5В500, installed with a pitch of 100 mm. Samples were loaded with two concentrated forces applied in thirds of the span. With composite reinforcement, the appearance of the external composite reinforcement was varied, as well as the presence or absence of U-shaped anchoring clamps glued to the supporting sections of the beams. It has been established that the greatest reinforcing effect is provided by composite materials based on carbon fibers, in which the modulus of elasticity is comparable to the modulus of elasticity of steel.

Keywords: concrete, reinforced concrete, bending element, composite, fiberglass, carbon fiber, strength, deformability

" During a long interruption of construction and installation works, as well as under the influence of the external environment on the unfinished construction of building structures, they are subject to a change in their properties and strength characteristics. To solve all problems, it is necessary to conduct a forensic examination in order to identify defects and assess the state of building structures and make decisions on the possibility and feasibility of completing construction work"

Keywords: construction in progress, expertise, defect, building construction, laboratory tests, design documentation, expert

The article discusses the current problems of calculating the distribution of water flow; the problems of current methods based on solving nonlinear equation systems are identified; proposes a new method for solving problems; analysis of the effectiveness of the proposed method; proposed a way to optimize the simulation calculations.

Keywords: waterways, water expenditures, modeling

Fractal geometry is used in the development of new designs based on the principles of fractal shaping and the study of generations of fractal structures. The structure generation is characterized by optimization of the original geometry in the process of iteration. Fractal structures of older generations have the best indicators of reliability. The aim of the study is to develop an algorithm for modeling new designs based on the principles of fractal shaping. The development of fractal structures requires the creation of new technologies and materials.

Keywords: fractal structure, generations, fractal geometry, shaping, self-developing structures, unique structures, 3D modeling

The article presents the algorithm of the step method for determining the limit loads for elastic-plastic rod systems. The development of the iterative process with the hypotheses used is given, taking into account the influence of the moment and longitudinal force on the limit state of individual sections, the lenght of the plastic deformation zones along the lenght of the rod. The advantage of the step-by-step method for determining the limit loads in rod systems in comparison with the "direct method " of A.R.Rzhanitsyn is demonstrated. The functions of forms depending on the type of section in explicit form are defined; the algorithm of tabulation of the form function is developed.

Keywords: slab and pile foundation, settlement of the building,stress-strain state,homogeneous anisotropic analog,finite element method

The analysis of methods for assessing the quality of work on the consolidation of soil massifs with different compositions was carried out, the shortcomings of the existing methods were noted. A new device for determining the properties of a soil massif, fixed by the method of reinforcement with cement-sand mortar, was proposed. The design and features of the application of the developed device for evaluating the deformation properties of a fixed array are described. An example of obtaining and processing the results of soil tests by the developed device is given.

Keywords: soil reinforcement, cement-sand mortar, quality control, die tests, geophysical methods, drilling, draft, deformation module

The problem of calculating rods for vector perturbations consisting of five components is solved: 1. kinematic transverse vibrations of the left end; 2. kinematic transverse vibrations of the right end; 3. dynamic bending moment at the left end; 4. dynamic bending moment at the right end; 5 dynamic uniformly distributed lateral load along the length of the rod. The transfer functions from each disturbance are obtained separately. Using these functions, we obtained the elements of the spectral matrix for stationary random processes, taking into account their correlation. The most common types of processes are considered: exponentially correlated random process; process with latent periodicity (with characteristic frequency); truncated white noise. The formula for obtaining the dispersion of displacement of sections is shown.

Keywords: rod, harmonic oscillations, natural frequency, kinematic disturbances, dynamic disturbances, transfer function, correlation matrix, random process, delta-correlated random process, latent periodicity, truncated white noise

The dependence of influence of size of a bend on tensely strained state of load-bearing frames of a covering is analysed. On the basis of the received results the maximum corner of a bend of the metal corners reducing a carrying capacity of farms is defined.

Keywords: a rafter farm, bend, tensely strained state, a moment of inertia, a radius of gyration, a barycentre

The article deals with the construction and definition of the stress-strain state of the design scheme of a lattice tower-like structure in the form of a mesh hyperbolic paraboloid. The dependence of the wind load distribution on the characteristics of the form is established, a sectional calculation method for such structures is given.

Keywords: Hyperbolic paraboloid, finite element method, aerodynamic loads, lattice towers

The article discusses the dynamic characteristics of mineral wool materials (dynamic modulus of elasticity and stiffness, reduced dynamic stiffness) and the effect on them of porosity and relative deformation of the material. The main objective of the study is to determine the value of the dynamic modulus of elasticity, taking into account its change with time under the action of a long-term static load for calculating the impact noise insulation.

Keywords: mineral wool material, dynamic modulus of elasticity, strength of parts of a structure, sound insulation, ultimate states, construction

the article considers behaviour of a simply supported pre-cracked beam made of elasto-plastic material. The aim of the work is to study propagation of min-span fractures in the beam, defining of its behaviour in the local area and developing of techniques and methods to prevent further growth of a crack. There were applied vary verify methods to analyse deflections, internal forces and stress intensity factor in the area of crack propagation. Analytical and numerical calculation had been used. For numerical solution ANSYS software is used, based on finite element method. According the solutions key features and conclusions are given.

Keywords: fracture, pre-cracked beam, stress intensity factor, load-bearing capacity, elasto-plastic material, finite element method

In article results of the analysis of method of calculation of flat plates of girderless floors are considered on breakdown according to the Russian and foreign design codes are considered. The analysis of the received results demonstrates that in the considered calculation procedures on breakdown similar settlement models are used and identical power factors are considered. Namely the pressing-through effort and the bending moments operating in two planes. Taking note of the moments in various techniques is carried out in two ways. The first way – tangent tension is entered into settlement model. And each technique offers the form of an epyura of tangent tension. The second way – introduction to a condition of durability of the empirical coefficient considering influence of the bending moments. Approach to purpose of geometrical parameters of a settlement (critical) contour is not identical. Contours of different techniques differ in a form and the sizes. And the difference of the sizes is very considerable. It is established that work of knot of interface of girderless flag with a column is studied yet not fully and additional researches on generalization of calculation procedures are required.

Keywords: reinforced concrete, girderless floor, breakdown, working height of section, transversal armature, pyramid of breakdown

In the present work determined the specific tensile strength of the samples connected to various mounting accessories brand "MDM-Komplekt" and justified her choice to secure parts for various purposes. The study showed that the mounting hardware differs not only in ways of fixing the two parts and the invisibility of fasteners, but also important is the ability of a particular screed to resist loads exerted on the unit

Keywords: Cabinet furniture, fittings, tensile strength, laminated chipboard

The results of the study of the stability of the core structure of a polygonal ring under the action of a system of self-balanced radial forces are presented. A complete solution of the problem is given in accordance with the fundamental equations of the theory of R. Mises as applied to a statically definable planar structure. It is established that the instability parameter of the core structure of the hexagonal ring is determined solely by the number of nodal points of the hinged rod system.

Keywords: core structure, regular polygon, hyperboloid, annular diaphragm, determinant, characteristic polynomial, cyclic symmetry

The article discusses the process of sulfuric acid alkylation used to produce high-octane gasoline, as well as the design of jet reactors, their advantages and disadvantages. Based on the existing drawbacks of jet reactors, the development of a new high-efficiency jet reactor design has been proposed.

Keywords: reactor, sulfuric acid alkylation, isosurface, isocontours, gasoline, fractions, jet type, industry, oil refining

The principles of parametric modeling and design based on the example of a buildings is studied, the architectural image of whiches are a set of spiral circular surface with circles of variable radius defined by coordinates through functions of the corresponding surfaces in the SAPPHIRE software. Alternative methods for specifying surfaces in the SAPPHIRE PC with subsequent export to the LIRA PC for engineering calculations of the frame of the building for various combinations of loads by the finite element method are presented. The object of the study is a 130-meter-high building with a hardness core in the form of a cylindrical shell of revolution. One of the most universal ways to create a surface is to specify it through a formula, because you can easily change the shape and appearance of the surface without manually editing the geometry of the model in the drawing. The development of the parametric architecture calls for the creation of new approaches to the calculation of unique buildings and structures, the improvement of software complexes that implement the finite element method, and the appearance of new varieties of finite elements with curvilinear boundaries.

Keywords: parametric architecture, surface, shape of the object, shell, curve, model, geometry, program, formula surface, helical surface

The problem of lateral buckling of a free-supported wooden strip with a constant narrow cross-section loaded with concentrated force in the middle of the span is considered. In the study of lateral buckling of the beam was used energy method. For the case of load application in the center of gravity, the problem is reduced to a generalized secular equation. The dependence between the value of the critical force and the position of the point of application of the load is obtained. A linear approximating function is chosen for this dependence. The results obtained by the authors are compared with the analytical solution using Bessel functions and the numerical iterative method.

Keywords: thermal conductivity, finite element method, the steady-state temperature field, radiation-heat shield, thick-walled cylinders

This article presents the rationale for the selection of measuring instruments (strain gauges) for testing light steel thin-walled structures (LSTC) to determine the stress-strain state. Article discrebes in detail optimal sensor's installation locations, the required measures for correct value.

Keywords: thin-walled profile, test, frame, strain gauge, compression, tension, tension, bending, loss of stability

Outlines the main provisions of the calculation of the stability of statically indefinable systems of regular structure. A planar structure with an external contour in the shape of a regular hexagon and under the action of nodal radial compression forces is considered. An analysis of the stability of the equilibrium state of the core structure is performed and the full range of numerical values of the instability parameter of the system is determined.

Keywords: core structure, regular hexagon, hinge system, characteristic polynomial, triangular panel

The paper is concerned with relevant stress concentration research in construction elements made of structurally heterogeneous materials. On the base of the physico-mechanical model of structurally heterogeneous body (polycrystal) , with the use of finite elements method, stress distribution in construction elements made of polycrystalline metals with hexagonal lattice (magnesium, titanium, zinc) is investigated at various stress states. Coefficients of stress concentration in plates with circular holes are determined in the case of uniaxial tension, uniform biaxial tension, and pure shear. It is demonstrated that stress concentration coefficients calculated regarding microstructural factors of stress concentration can take values that considerably differ from values for isotropic body, depending on anisotropy of elastic properties of polycrystalline metals and a type of stress state

Keywords: linear and plane stress states, polycrystalline structure, microstructural factors, nonuniformity of stress

The results of tests of a series of single-shear samples of joints of wooden elements on inclined metal rods (IMR), in which plain washers transmit the force between the rod and wood, are considered. The intended bearing capacity of the NMS-connection is determined by taking into account changes in SP 64.13330.2017. Theoretically and based on experimental data, the stress-strain state of an IMR connection and the stress state of inclined steel rods are considered. The prevailing factors in the stress state of inclined rods are established. The estimation of the bearing capacity of IMR-connections on the rods with plain washers performed.

Keywords: Wooden structures, ductile connectionions, NMS-connection, inclined metal rods, intended bearing capacity, shearing load, tensile stress, ultimate breaking load, bearing strain under washers, safety factor

The paper deals with the results of study on the degrees of stress inhomogeneity caused by interaction between differently oriented crystalline grains in macrovolumes in case of non-uniform uniaxial tension. Calculation of finite element volume consisting of forty grains is performed. It has been revealed that the quantity of forty grains is enough for constituting the smallest body volume, which can be assumed to have the averaged properties of a macrovolume. Directions of crystallographic axes were selected randomly. Calculations were performed for various metals with cubic and hexagonal lattices. Based on the results of calculations, the curves of normal stresses in the central cross-section of the elementary volume were constructed. It has been found that the significant exceedance of normal stress values is possible in comparison to the values calculated for quasi-isotropic fine-grain material. Dependence between the degree of stress inhomogeneity and the degree of anisotropy of elastic properties has been demonstrated

Keywords: microvolume, macrovolume, non-uniform tension, degree of stress inhomogeneity

The paper deals with the study of the dynamic characteristics of the coating farm. Due to the changes in the company's technological regulations, it became necessary to install additional ventilation equipment with its output to the roof of the shop. The study showed that to ensure safe operation in the structural scheme of bearing structures it is necessary to organize additional units. Dynamic load on the supporting structures is created by the operation of ventilation equipment. The spectrum of natural oscillation frequencies is determined. The values of these frequencies were compared with the frequency of forced oscillations of the fans. Graphs of the changes in natural frequencies when the fan operating frequency. According to the chart, when the frequency of the driving force coincides with the frequency of natural oscillations, the inertia forces increase sharply, which indicates the passage of the resonance zone. A study of changes in dynamic forces due to rotor imbalance was conducted. The value of the gap arising at wear of bearings at which there will be a destruction of a basic element of a farm was calculated.

Keywords: vibrations, forced vibrations, frequency, resonance, truss