Cantilever Part Research Articles

ВАРИАНТЫ РЕКОНСТРУКЦИИ БОЛЬШОЙ СПОРТИВНОЙ АРЕНЫ СТАДИОНА «ЛУЖНИКИ» К КУБКУ МИРА ПО ФУТБОЛУ В 2018 ГОДУ

The article presents the results of comparing the options for choosing the type of console part, which is additionally mounted to increase the coverage area, which is necessary to meet the strict requirements of the International Football Federation (FIFA) for the possibility of holding the opening and final matches of the FIFA World Cup at the stadium. Based on the results of comparing the options, the type of cantilever part and the roof material were selected, the process of determining snow loads obtained by blowing the frame model in a wind tunnel is presented. The paper presents the main results of the calculation, as well as the first values of the natural shapes and frequencies of vibrations. The surface was reconstructed for the 2018 FIFA World Cup in Russia, which made it possible to successfully host the opening and final matches of the championship and increase the prestige of our country in the world.

ИССЛЕДОВАНИЕ ПРИЧИН ПРЕЖДЕВРЕМЕННОЙ ПОЛОМКИ КОРОНКИ СТОЙКИ РЫХЛИТЕЛЯ, ПРОИЗВЕДЕННОЙ С ПОМОЩЬЮ ТЕХНОЛОГИЙ ПРЯМОГО РЕИНЖИНИРИНГА

Abstract.. When testing imported ripper bits for bulldozer equipment, their premature failure was observed. In the process of studying the loading of the crown by the contact pressure of rocky soils at P = 11.5 MPa, it turned out that only a tight, gap-free installation of the crown on the seating part of the ripper strut ensures reliable operation and protection of the strut from wear and promotes its long-term operation in conditions of rock crushing. It has been established that the strength condition for the crown is satisfied only in the case when the landing part of the crown itself maximally touches the landing part of the ripper post, that is, the contact of the crown with the post is carried out along the maximum area of contact - contact. In this case, equivalent stresses are observed that are less than the yield stresses for steel, which was proposed in the study as wear-resistant for working on rocky soils. The study carried out numerical calculations of stresses and displacements in the crowns for various methods of their attachment to the landing part of the ripper strut. In the first case under consideration, the strength conditions are observed when the crown is working on rocky soils; in the second case under consideration, the strength conditions are not met and characteristic places are shown in which the safety factor is less than 1.3 (30%). Based on the results of the study for this case (numerical modeling), it was decided to increase the cross-section of the transition point of the cantilever part of the crown to its landing part by 10%. At the same time, it was determined by calculation that with an increase in the cross-sectional area of the transition point of the cantilever part of the crown to its landing part by 10%, operational reliability will increase by 20-30% when the ripper operates on rocky soils. As a result of the study, the possibility of using steel grade for crown-type products was experimentally confirmed.

Flexural and Shear Deformation of Basement-Clamped Reinforced Concrete Shear Walls.

For a precise analysis of buildings under earthquake effects, the load-deformation behaviour of the bracing walls must be comprehensively known. The horizontal bracing walls are often clamped in the basement; however, less attention has been paid to these walls' clamping parts in the past. This study presents three shear wall experiments (NW 1, NW 2, NW 3) with heights up to six meters in a scale of 1:1.5 to the real size. Measured were the force-displacement curve, the curvature distribution over the height, the crack pattern, and the crack opening and spacing. Twelve displacement transducers, an optical measurement system with eight cameras, and a manual crack measurement were utilised. Out of the measurements, the impact of the tension shift effect on the load-displacement curves could be quantified for the cantilever part of the walls. Additionally, it was found out that a sliding failure in the clamping part must be considered if the aspect ratio of H/L is equal to or less than one.

FEATURES OF VIBRATION DAMPERS APPLICATION IN THE DESIGN OF VIBRATION-RESISTANT METAL CUTTING TOOLS

Dry and viscous friction is used as a damper of oscillation energy in the construction of metal-cutting tools. A mathematical model of a two-mass oscillatory scheme of the insert of an assembled milling cutter was developed and studied, one of the masses of which models the clamped part of the insert - a press connection with dry friction, and the other - the cantilever part, which is subject to self-oscillations that are possible in the process of metal cutting. The influence of dry friction in the press joint of the insert on the amplitude of resonant oscillations of the cutter and the part was analyzed. The possibility of reducing the magnitude of the cutter's self-oscillations is demonstrated by selecting the most suitable parameters for the press connection of inserts with the body of the assembled milling cutter. The influence of internal viscous friction in materials with a high level of energy damping on the amplitude of self-oscillations of the cutter was evaluated and the possibility of their use in the design of a vibration-resistant metal-cutting tool was considered.

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ СЕРІЙНОЇ ДОРОЖНО-АЕРОДРОМНОЇ ЗАЛІЗОБЕТОННОЇ ПЛИТИ

The results of experimental studies of the load-bearing capacity and crack resistance of the serially produced road-airfield reinforced concrete slab PAG, manufactured at Velikodolinsky Reinforced Concrete Plant LLC by order of the Odessa State Academy of Construction and Architecture, are presented. In accordance with the regulatory documents in force in Ukraine, one of two possible loading schemes was considered ― with a load by a concentrated force applied on the cantilever part of the slab. The slab was tested on a specially made stand, which consists of four support posts connected in pairs by beams on which the slab rested. The load was applied along the width of the slab in steps ― 0.04 from the destructive load, along two concentrated vertical stripes. Each load stage ended with a five-minute hold, at the beginning and end of which readings were taken on the measuring instruments. All tests were carried out using two 30t jacks and a 50t dynamometer. The principle of operation of the jack was that its lower plane pressed on a two-level cross-beam system, and through it the load was distributed onto the slab. During testing, the applied load, deflections and deformations were recorded on the slabs. Dial indicators and deflectometers were used as measuring instruments. The process of crack formation on the surfaces of the slabs was observed using a Brinell tube in the places of the greatest opening of the cracks. As a result of the tests, the load-bearing capacity of the slab was 163.2 kN with a bending moment of 78.3 kNm. The load corresponding to the onset of cracking is 86.4 kN with a bending moment of 36.9 kNm. The maximum crack opening width was 1.0 mm. Based on the indicator readings, graphs of the dependence of relative deformation on load were constructed. Graphs of the dependence of deflections on load are constructed using data from two deflection meters. Before the first crack appears, the maximum deflection of the slab is 12.0% of the deflection recorded at the end of the tests.

EXPERIMENTAL STUDIES OF SERIAL REINFORCED CONCRETE PAG SLAB WITH ADDITIONAL STEEL FIBER REINFORCEMENT

Thus, in laboratory conditions, experimental studies of the bearing capacity and crack resistance of a serial PAG plate with additional steel fiber reinforcement in the amount of 1% were carried out. In accordance with the regulatory documents in force in Ukraine, one of two possible load schemes was considered ― when loaded by a concentrated force applied to the cantilever part of the slab. The plate was tested on a specially made stand consisting of four support racks connected in pairs by beams on which the plate rested. The load was applied across the width of the slab in steps of 0.04 from the destructive load, in two concentrated vertical strips. Each level of load ended with a five-minute exposure, at the beginning and end of which the readings on the measuring devices were taken. All tests were carried out using two 30-ton jacks and a 50-ton dynamometer. The working principle of the jack consisted in the fact that its lower plane pressed on a two-level cross-beam system, and through it the load was distributed on the slab. In the process of testing the plates, the applied load, deflections and deformations were recorded. Clock-type indicators and protractors were used as measuring devices. The process of crack formation on the plate surfaces was observed with the help of a Brinell tube in the places of the largest crack opening. 
 As a result of the tests, the bearing capacity of the plate was 211.2 kN with a bending moment of 101.4 kNm. The load corresponding to the beginning of crack formation is equal to 96.0 kN at a bending moment of 46.1 kNm. The maximum width of crack opening was 0.25 mm. According to the readings of the indicators, graphs of the dependence of the relative deformation on the load were constructed. Graphs of the dependence of deflections on the load, constructed from the data of two deflection gauges. Before the appearance of the first crack, the maximum deflection of the plate is 17.0% of the deflection recorded at the end of the tests.

Tuning the flexural frequency of overhang-/T-shaped microcantilevers for high harmonics

High-harmonic (HH) frequencies in microcantilevers impose several applications in precision detection thanks to the higher sensitivity of the higher modes in comparison to the fundamental modes. In this study, we showed that by tuning the cantilever length by changing the clamped position, the dimensional ratio of the overhang to the main cantilever part is altered and the HHs could be effectively obtained. Multiple HH frequencies have been achieved, from the 4th to 8th order of the second and from the 11th to 26th order of the third-mechanical mode versus the first mode, and these orders are much higher if higher modes are used. The analytical calculation is in agreement with available results of other groups. HH behavior when the cantilever interacts with the sample is also examined and is strongly dependent on the overhang parameters. These results could guide the experimentalist in the tuning and controlling of the HHs in detecting objects.

INVESTIGATION OF THE PASSAGE OF VIBRATIONS THROUGH A FIXED SECTION OF AN ELONGATED PLATE CAUSED BY THE ACTION OF THE AXIAL FORCE AT THE END

A method has been developed for the experimental study of forced elastic vibrations of a cantilevered thin-walled structural element in the form of a rod-strip, excited due to the passage of vibrations through the section of a finite length fixed along one of the surfaces caused by axial loading by a harmonic force applied to the end of the fixed section. The experimental dependence of the amplitude values of the vibration accelerations of the point at the end of the console on the frequency of the excited bending vibrations of the end of the rod is obtained, indicating the passage of vibrations through the fixing section of the finite length, which occurs due to the transformation of longitudinal vibrations in the loading zone into longitudinal-transverse-shear vibrations of the rod-strip in the fixing zone, followed by their transformation into predominantly bending vibrations of the cantilever part of the rod. For the theoretical study of the described phenomenon, a transformational model of deformation of the rod-strip is constructed, taking into account the deformability of the fastening section of finite length on the basis of the refined model of S. Timoshenko. The cantilever part of the rod is represented by the classical Kirchhoff-Love model, taking into account geometric nonlinearity in determining axial deformations. The kinematic conditions of coupling of the fixed and cantilever parts of the rod are formulated. On the basis of the Hamilton-Ostrogradsky variational equation, the equations of motion of the non-fixed and fixed parts of the rod, as well as the boundary conditions for them and the force condition of conjugation of the marked parts of the rod are obtained. Numerical experiments have been carried out for a rod-strip made of aluminum alloy D16AT, showing a noticeable passage of vibrations through the fixing section of the final length into the cantilever part of the rod with a decrease in the dynamic shear modulus of the material to a certain value.

Numerical investigation into laser-based powder bed fusion of cantilevers produced in 300-grade maraging steel

Laser-based powder bed fusion of 300-grade maraging steel allows the production of parts with a high hardness, which improves the service life and wear resistance of tooling or mould insert produced from this material. The material typically consists of a martensitic matrix material, with retained austenite and nano-precipitation. The transformation from austenite to martensite has been linked to compressive stresses at the surface of parts produced in 300-grade maraging steel. In a cantilever beam-type part, this means that after cutting from the base-plate, the part will bend downwards, which is the opposite direction from the deformation found in most other materials after additive manufacturing. One way to gain insight into processing 300-grade maraging steel, while limiting the number of test samples that need to be printed, is by means of a numerical model. Using previously established models, additive manufacturing of a cantilever part in 300-grade maraging steel is simulated. Inclusion of the transformation from austenite to martensite into a numerical simulation of the laser-based powder bed fusion revealed the origin of the compressive stress at the surface of a simple cantilever beam-type sample. Additionally, changing the effective laser power through the laser absorptivity shows that the behaviour of the post-cutting deformation flips as compared to more conventional materials. Information about the laser absorption coefficient is rare, while it can greatly affect the results of a simulation. It is included in the presented result through the effective laser power, which is the product of the input laser power and laser absorption coefficient. When the effective laser power is changed from 95 W to 47.5 W, the cantilever bends upwards rather than downwards after release from the base plate. The results demonstrate the major influence played by the laser absorption coefficient on the simulation, an aspect to which little attention is paid in literature, but is proven to be one of the main factors to determine the component distortions after the laser-based powder bed fusion process.

DEFORMABILITY AND CRACK RESISTANCE OF AIRFIELD SLABS

Abstract. The results of experimental studies of deformability and crack resistance of models of airfield slabs made of reinforced concrete and steel fiber concrete are presented. Two series of plates were tested ‒ three models of reinforced concrete and three models with steel fiber added to the concrete mixture in amount of 1% of the total volume of the product. The load was applied in small steps, the instrument readings were recorded twice at each step, and the crack opening width was measured starting from the moment of the first crack formation. Dial gauges and deflectometers were used as measuring instruments. According to the normative documents acting in Ukraine, one of two possible loading schemes was considered ‒ with the loading by the concentrated force applied on the cantilever part of a plate. The plate models were tested on a specially made stand which consisted of four supporting struts connected in pairs by beams. The airfield slab was supported by the beams. The load was applied along the width of the plate in steps ‒ 0.05 of the destructive load, along two concentrated vertical strips. Each degree of load ended with a five-minute dwell time, at the beginning and end of which readings were taken on the measuring instruments. The deformations at the same levels were measured with dial gauges. The process of crack formation was observed with a Brinell tube in the places of the greatest crack opening. It follows from the obtained results that the process of cracking in the fiber concrete slab begins at higher loads than in the reinforced concrete slab. The final and initial crack opening widths of all cracks in the fiber concrete slab are significantly lower than in the reinforced concrete slab. The deformations in steel-fiber concrete slabs during the application of load in the cantilever part, both for compressed and stretched fibers are higher than in reinforced concrete slabs. At the initial stages of load application in the cantilevered part of the slabs, the deflections increase in a linear relationship. The curves get non-linear character for airfield slabs made of reinforced concrete when the load reaches the level of 10÷25 kN, for steel-fiber-concrete slabs ‒ 15÷30 kN. In reinforced concrete slabs, the non-linearity starts a little earlier and is expressed more clearly. Experimental studies show that dispersed reinforcement of airfield slabs with steel fiber leads to their higher crack resistance.

Modelling of machining center vibration stability by the D-partitions method

The stability of operation, vibration-free processing of products various types at high-speed machining centers suggests the improvement of research in the field of the dynamics of machine tools and their main forming units. The three-dimensional models of the forming spindle node and the corner table of the machining center for the drilling-milling-boring type in the CAD environment KOMPAS-3D have been developed. An algorithm for analyzing the dynamic quality of the machine elastic parts based on the constructed static and frequency formular in the mathematical environment MAPLE is proposed. Programs have been developed and graphs of the main frequency characteristics and the hodograph of the transfer function for the spindle node in the specialized Signal Processing module have been obtained. The method of D-partitions using to estimate the vibration stability of the forming units on an example of 4 coordinate milling machining centers is introduced. Experiments on two variants of technological adjustments with different dimensions of the tool block (the cantilever part of the spindle assembly) were carried out. The analysis of stability in the plane of the cutting process optimized parameter (specific cutting force) was carried out. The region and the boundary of the stable functioning of the machine and, on this basis, the optimum modes of machining by the criterion of vibration stability are revealed.

Seismic review of spiral façade building collated by rotated cantilever beam

Exposing building façade has led to a magnificent look of the whole building structure creating the assumption of a complicated building structure. Spiral and free form building shape deliver the volatility of the design process not only because of static loading but also dynamic loading such as an earthquake. Modifying an octagon building core throughout its façade by applying an extension cantilever beams and rotating them is the main approach served in this paper establishing a spiral high-rise building. The angle of rotation is varied from 0 to 5 degrees per floor in order to see the stability of the building structure under dynamic loading. The length of the cantilever beam is restrained up to 9 m with the rotating path of an ellipse. The greater the rotation angle, the extreme cantilever beam length in some points. The displacement represents various unpredictable result as the rotation angle livened up as 2-degree and 3-degree rotation angle provides worst. Even though the spiral shape is enormous, the cantilever beam capacity grows critically particularly due to the torsion. Furthermore, reinforcement for the cantilever part must be well confined in order to increase the performance.

Single-Level Station Complex Structure for Application of Through Driving Construction Method

Metro Service has a huge impact on the development of urban transport infrastructure. The need to increase the efficiency of passenger transportation is caused by the rapid growth in passenger turnover as well as an increase in the distance from the outskirts of the city to the center. In connection with the need to develop a metro service network in Minsk city, which is confirmed by research in the area of passenger traffic in the main areas of the city, the CSM Bessac tunnel boring machine was purchased, which allows significantly to increase the speed of tunnel driving. The use of a mechanized tunnel boring machine in the traditional concept of the metro network construction, in which driving of tunnels is carried out after construction of stations, does not allow to use a shield with maximum economic efficiency due to the small extent of tunnels. There is also a need to build assembly-shield chambers and carry out works on disassembling and assembling the shield. The application of the new concept developed by Yu. S. Frolov and called “through driving” is actual in the conditions of the use of a mechanized tunnel boring machine. Its essence lies in the continuous driving of tunnels on the line section under construction and the consecutive construction of each station complex as the tunnel boring machine passes through it. To implement the concept of “through driving”, it is relevant to use a semi-closed construction method, in which the floor structure is constructed in an open way, and the other elements are closed. The available solutions of the metro stations constructed while using a semi-closed method of work have been analyzed in the paper. A detailed analysis has been carried out with due account of the adaptation to the construction conditions in Minsk, and the development of structural elements and assemblies of the platform area of the station, which is a two-cantilever vault with a developed transom part, resting on pile-columns of a circular cross section. Forces from the open ring of flexible tunnels lining are supported by a cantilever part of an arch and a bottom plate. The paper considers a design of a metro station, its main elements, their purpose and specificity of work, as well as optimization issues and the results of the design feasibility study.

Topology optimization of lattice support structures for heat conduction in selective laser melting

Support structures are required in selective laser melting process to support overhanging surfaces in order to remove heat away from the process and to reduce geometrical distortions. Heat stress and warping may occur due to heat accumulation in overhangs. These ultimately affect the dimensional and geometrical accuracy of the part. Therefore, this work introduces an approach to mitigate heat stress by maximizing the heat conduction of support structures. The minimum thermal compliance is set as an objective function to use a method of three-dimensional topology optimization to generate lattice support structures. In addition, fabrication experiments were conducted to investigate the warpage and levelness of the final built cantilever parts supported by our support structures and the three conventional support structures including pillar, wall, and “IY” support structures. The experiment results revealed that the warpage deformation of the cantilever part supported by our support structures is the lowest. Compared with the pillar, wall, and “IY” support structures, the top surface warp deformation of the cantilever supported by our support structures is reduced by 25.4, 31.75, and 17.65%, respectively. Moreover, the experiment results also indicated that the collapse and cracking of the built cantilever part supported by our support structures is significantly reduced compared with the conventional support structures.

SUBSTANTIATION OF TECHNICAL COMPATIBILITY OF NECKLACE RAILWAY STATIONS AND ROLLING STOCK

Purpose. The purpose of the study is to substantiate the technical compatibility of the switch necks of railway stations and rolling stock. Technique. Technical compatibility of the necks of railway stations and rolling stock means the method of interaction of the elements of the structures of the switch necks and rolling stock in accordance with the established safety requirements. As criteria for evaluation of technical compatibility of elements of structures of switch necks and rolling stock, compliance with conditions of car movement in a coupling and their automatic coupling is accepted. Analysis of the established methods of determining the spatial-coordinate relationship of the track infrastructure and rolling stock in the horizontal plane showed that deviations of its control points from the track axis play a decisive role. These phenomena depend on two groups of factors: the parameters of track structure (the presence and parameters of curves, straight inserts, their mutual placement) and the design of the rolling stock (the length of the bases of the trolley and car, the length of cantilever part, the design features of the trolleys, the amount of grip and the angle of deviation of the automatic coupler). Graphical and analytical methods of determining the corresponding radius values are proposed to evaluate the design of the switch necks according to the condition of providing automatic adhesion. The study also obtained an expression for directly calculating the radius value that ensures safe movement in the coupling depending on the angle of deflection of the automatic coupler shank. This made it possible to assess the ability to interact with each other of the structure elements of and rolling stock when moving in a coupler depending on the position of the automatic coupler elements (skewed and not skewed position of the traction clamp, taking into account the normal or buried position of the automatic coupler). To determine the complex criterion in designing the necks of railway stations providing technical compatibility with rolling stock, a comparison of permissible radii during automatic clutch and clutch movement for various types of rolling stock was made. The values of radii that provide automatic adhesion are 1.3-3 times higher than those required for effective movement in the coupling (even when the shank of the automatic coupler is buried). Therefore, as a complex criterion of technical compatibility in the development of requirements for the design of switch necks of railway stations, the condition of automatic adhesion can be adopted. Results. It was obtained that the values of deflection angles at different positions of automatic couplers can differ more than twice, which requires additional restrictions when maneuvering with groups of cars. The calculations confirm the possibility of power interaction of the automatic coupler elements due to non-conformity of the design standards of track structure and rolling stock. In addition, in the designs of existing necks of railway stations, more than 20% of curves have radii less than those allowed by modern design standards of railway stations, up to half - by the design standards of wagons of mass types and up to 80% - by the design standards of cars of increased size. This additionally reduces the technical compatibility of fishing mountains and rolling stock, creates excessive loads during interaction. The "gap" shown between the parameters of track structure and rolling stock can lead to a number of negative consequences associated with the processes of movement in the coupling and traction of cars. Scientific novelty. In order to ensure the safety and effectiveness of the interaction of the switch necks of railway stations and rolling stock, a method of comprehensive assessment of the track structures of railway stations according to the criterion of technical compatibility with rolling stock has been proposed; a simulation model of the interaction process in the track structure-car system has been developed, which allows determining requirements for structural schemes of track structure of a high degree of complexity; main taxa of interaction conditions are established; requirements of technical compatibility of switch necks of railway stations and rolling stock are supplemented; criteria for identifying calculated categories of cars were clarified, parameters of track structures were obtained that ensure technical compatibility of the necks of stations and rolling stock. Practical importance. The obtained technique can be used at stations to localize the most dangerous sections of tracks and identify the category of cars that cause operational restrictions in the operation technology. The application of the results obtained in the development of projects for the construction and reconstruction of railway stations, the production of switch products, and the improvement of rolling stock structures will ensure their technical compatibility and significantly improve operational quality.

Обоснование выбора точек подвеса транспортно-установочной тележки канатами механизма подъема на стартовых комплексах

The paper considers the problem of selecting the optimal weight and size characteristics of an erector frame for advanced super heavy-lift launch vehicle by selecting the suspension points of lifting mechanism ropes to the erector when transferring the rocket to a vertical position at the launch complex. The calculated dependences of frame weight and the force in polyspast system on the distance between the points of erector attachment to the racks of the launch pad and the points of erector suspension with the ropes are presented. The effect of the transverse width of the erector frame guide beams and the angle between the tight ropes and the horizon at the initial moment of lifting the rocket to the vertical position on the weight and dimensions of the erector is analyzed. According to the calculation results there is the possibility of a significant reduction in the weight, size and cost of the erector and the drives of lifting mechanisms in comparison with the case when ropes are attached to the cantilever part of the frame and systems using hydraulic drives as the lifting end organs of the erector beam.

Забезпечення вібростійкості процесу розточування однолезовим інструментом на токарному верстаті

Heightening of a chatter stability of boring process at turning is an actual problem. The basic circuit of a dominating vibratory system of process is developed for the theoretical analysis of oscillating processes for boring bars at boring process and the mathematical model of dynamic system of the lathe that allows us to define influence of design data of boring bars on a process of chatter stability is constructed. On the basis of mathematical model with use of transmitting function the influence of a direction of principal axises of rigidity of boring bar-slide elastic system on static characteristic of elastic tool system is determined. Experimental researches of boring bars have given the chance to define their frequency characteristics by a method of harmonic perturbation and to use them at boring process simulation. It is displayed, that ensuring of conditions of vibrational stability of internal turning on machine tools by boring bars can be carried out by a rational choice of their design data taking into account rational orientation of principal axises of rigidity of elastic tool system in relation to a direction of cutting force, a choice of a rational ratio of rigidity on these axes and heightening of damping ability of a cantilever part of boring bar.

Development of a method for calculating the stress state in horizontal sections of hydraulic engineering angular-type retaining walls

Angular retaining walls are widespread in hydraulic engineering. They are characterized by large dimensions, small percentages of reinforcement, block cutting along the height of the structure. The bulk of the existing retaining walls were built in the 1960s-1980s. The regulatory documents that were in force during this period had certain shortcomings that caused the non-design behavior of a number of retaining walls. Improvement of calculation methods for reinforced concrete structures of retaining walls is required, within the framework of which a more complete account of the characteristic features of their behavior is needed. The aim of the work is to improve methods for calculating reinforced concrete retaining walls of a corner type. Methods of research carried out to improve the calculation of reinforced concrete retaining walls of the corner type included, among others, the classical methods of resistance of materials, the theory of elasticity, and structural mechanics. To determine the actual stress-strain state of the natural structures of retaining walls, visual and instrumental methods for examining retaining walls were used, including the method of unloading reinforcement. Results. To determine the stress state in the elements of the reinforced concrete structure of the retaining wall (in concrete and in reinforcement), a methodology was developed for calculating the stress state of retaining walls, which allows to determine the components of the stress state (stress in concrete in the compressed zone, as well as stress in stretched and compressed reinforcement) in horizontal sections of the vertical cantilever part of the retaining walls.

Calculation of the length of the cantilever part of beam pipeline crossings based on the improved design scheme

During the design and construction of pipelines at the intersection of natural or artificial obstacles, various beam systems are used. They often include a compensator which must collect section elongations composed of temperature extensions from the internal pressure and longitudinal forces caused by longitudinal movements of the underground sections adjacent to the above-ground pipeline. This article analyzes sources that highlight the design of beam crossings with compensators. The design in which the maximum bending moment in the middle of the span and the support moment have equal absolute values is optimal. Based on the identified deficiencies of the design schemes, it was proposed to calculate the length of the single-span beam crossing with compensators using a different scheme.

MODERNIZED CALCULATED SCHEME OF BALL TRANSFER PIPELINE WITH COMPENSATORS

Background Currently, the design of temperature compensated above-ground beam crossings does not reflect the actual position of the pipeline in the field. In this regard, the analysis of research in this area and the creation of a new scheme are particularly relevant. Aims and Objectives The study aim is to determine the stress state of the transition and calculate the optimal length of the compensators. To achieve this aims, the following tasks are set: o analysis of the existing methods of calculation and assessment of the stress-strain state in the hazardous sections of the pipeline crossing; o development of an alternative method of calculation. Methods Comparative analysis is used as the main method. For creation of the settlement scheme methods of building mechanics, and also software Maple 18 are applied. Results As a result of the carried out analysis of the research of the stress-strain state of beam transitions with the use of expansion joints of longitudinal deformations, various conditions of pipelines operation were studied, structural schemes and methods of their calculation were considered, data of expansion joints use in pipeline transport were analyzed. It was offered, the dependence of the length of the cantilever part on the span for some sizes of pipes is received on the basis of the revealed drawbacks of the existing methods of calculation the scheme representing a statically undefined frame construction.