Permissible Load Research Articles

CALCULATION OF THE MAXIMUM ALLOWABLE LOAD ON A REINFORCED CONCRETE PILE IN THE PROCESS OF DRIVING IT INTO THE SOIL

Due to the lack of technical standards (DSTU) in Ukraine for the technology and quality control of the installation of driven piles, the conditions for high-quality performance of pile driving are often violated, for example, the driving force exceeds the strength of the pile material. This leads to the destruction of piles, which is most characteristic of sandy soils. In the project documentation for the installation of driven piles, with rare exceptions, there are no restrictions on the value of the driving force based on the strength of the pile based on the material, mainly due to the difficulties that arise when calculating the maximum permissible load on the pile when it is deepened by driving the pile.According to amendment No. 1 to DBN V.2.1-10-2009 [2] the amount of Rstv. is determined by calculating the strength of the material in accordance with the requirements of DBN B.2.6-98; 2009 [3], while considering the pile as a rod rigidly clamped in the soil in a section located at a distance ℓ1 from the point of application of the compressive force (see Fig. 1 and dependencies (2), (3)).According to DBN B.2.6-98; 2009 [ 3 ], the amount of compressive load allowed for the pile material is determined by calculating the pile as an eccentrically compressed reinforced concrete element under the action of a longitudinal force, while taking into account the random eccentricity eo, which in any case must take at least 1/600 of the distance between its cross-sections, fixed from displacement and 1/3 - from the height of the cross-section. In addition, it is also necessary to take into account the influence of longitudinal deflection by multiplying the value of the random eccentricity eо by the coefficient η according to dependence (5).The specified recommendations of the DBN on determining the value of the compressive load allowed for the pile material refer to the pile as an eccentrically compressed reinforced concrete element in a static state, which does not take into account the influence of technological factors in the process of pile compression.Our experience of sinking piles at dozens of sites has shown that the impact of the pressing technology on the permissible load on a reinforced concrete pile during its sinking is manifested in the form of an increase in eccentricity due to technological factors. In table 2, the reasons affecting the eccentricity of the load on the pile in the process of its immersion are considered in various ways of creating a compressive force: due to the weight of the structures of buildings and structures; due to the weight of equipment or anchor loads; due to anchor devices.The article draws the following conclusions.1. When calculating the maximum permissible load on a reinforced concrete pile in the process of pressing it into the ground, it is necessary to take into account, in addition to the recommended DBN B.2.6-98:2009 [ 3 ] random eccentricity and eccentricity from longitudinal deflection, as well as technological eccentricity by multiplying the value of random eccentricity by the coefficient of working conditions piles when pressed.2. We proposed the values of the coefficients of pile operating conditions for determining the calculated technological eccentricity for different ways of creating a compressive force and different ways of transferring the compressive load to the pile (through the head or through the side faces) (see Table 3). These values are empirical, they will be adjusted as experience is gained in the application of the pile driving method.

Toxicological Evaluation of Contamination by Potentially Toxic Elements (PTEs) and Related Risks in the Surface Waters of Three Tidal Streams of the Niger Delta, Nigeria

This work investigated the physicochemical parameters and potentially toxic elements (PTEs) in the surface water samples collected from three tidal streams (Bonny, Krakrama and Buguma) in the Niger Delta, Nigeria. Potentially toxic elements such as arsenic (As), boron (B), cadmium (Cd), cobalt, (Co), chromium (Cr), lead (Pb), nickel (Ni) and selenium (Se) were analysed using atomic absorption spectrophotometer. Physicochemical parameters were evaluated in situ using portable instruments and also in the laboratory. These parameters and PTEs were used to compute the water quality index, comprehensive pollution index, pollution load index, metal evaluation index, and toxicity load index. The ecological and health risks were also analysed. The PTEs found in the water samples were higher than the acceptable limit by WHO standards and followed the trend of Ni > Pb > Cr > Co > Se > As > Cd > B. Nickel was the most abundant element in water with the maximal concentration of 5510 µg L-1. The calculated contamination indices concluded that the streams were extensively polluted. Based on the permissible toxicity loads, maximum of 99%, 100%, 98%, 98%, 100%, 99%, and 97% of As, Cd, Co, Cr, Pb, Ni and Se respectively should be removed from the surface water of the streams in the Niger Delta to address safety and health. The PTEs in water exerted very high ecological risks. Overall, the estimated lifetime cancer risk of PTEs due to ingestion of water at Bonny, Krakrama and Buguma streams were 5.72 x 10-3, 2.88 x 10-3 and 2.3 x 10-3 respectively. The results guide controlling the PTE pollution and important information on PTEs for the formulation of the necessary remediation policies to improve water quality and protect the human health of dwellers along the Niger Delta.

Experimental Quantification of Fire Damage Inside Pyrotechnic Stores

A fire inside a pyrotechnic store can lead to simultaneous initiation of the stored articles, regardless of their risk category, producing a shockwave caused by the released gas pressure. In fact, several accidents have occurred throughout history in pyrotechnic stores. This indicates the high risk posed by pyrotechnics due to their flammability. Due to the lack of global or European legislation on guidelines for the design of pyrotechnic stores and associated risk assessment, the present research aims to analyze the consequences of a fire inside pyrotechnic stores and to establish globally possible effective prevention and protection measures in order to reduce explosion risk and avoid future accidents. The observed consequences and the reflected pressure (pressure measured when the wave is incident perpendicularly on the transducer) measured during fire tests inside a pyrotechnic store indicated the need to minimize the potential occurrence of fires. The limitation of the maximum permissible load, considering the volume of the store (kg/m3), reduces consequence severity in the event of an accident. However, the maximum permissible levels should be so low as to make their use for retail sales of pyrotechnic products unviable. The solution is the use of automatic fire detection and extinguishing systems with a high cooling capacity in order to prevent the spread to nearby packaging by rapid detection.

Avoiding Disputes in PPP Road Contracts: Quantifying Impacts of Increased Allowable Truck Loads

Dealing with changes is one major concern in long-term public-private partnerships (PPP) concessions, especially during the implementation phase, as some changes might lead to disputes between PPP partners and disrupt the successful execution of the project. In the transport sector, a change in the law regulating truck loading standards inevitably influences the financial stability of road projects procured through PPP. That is, the government’s decision of increasing the permissible truck load can lead to an accelerated deterioration of the pavement, and accordingly imposes additional expenditures that are borne by the concessionaire for maintaining the road condition at a satisfactory level, as required by the PPP contract terms. Given the fact that PPP concessions allow for additional compensations to the concessionaires in the case of modifications in the legislative and regulatory conditions, this study proposes two remuneration strategies for consideration by the concerned government to mitigate the adverse implications of increasing truck load limit on the concessionaire’s financial status and consequently to avoid the occurrence of disputes with the concessionaire. The work presented herein is twofold, as it quantifies the impact of the change in truck load regulations on two main contract terms: the toll regime and the concession period. Under the first approach, the government would provide direct compensation to the concessionaire through a shadow toll paid per overloaded truck. The value of the shadow toll was found to be largely influenced by the truck class, truck load, pavement structure, climatic conditions and traffic volumes. Moreover, it was found that the highest values of shadow tolls would apply to projects with relatively thin pavements and high traffic volumes. Under the second approach, an extension of the concession period was considered, which allows the concessionaire to recover the increased pavement maintenance costs. It was found that the length of the extended term depends, to a great extent, on the project’s characteristics in terms of the pavement structure, climatic conditions, traffic volumes, and more importantly on the toll revenues generated during the extended period. The two proposed alternative compensation techniques were devised and demonstrated through a methodology that involved flexible pavements performance prediction under varying loading conditions, using AASHTOWare Pavement ME. The proposed methodologies represent a framework that helps the two main parties involved in a PPP road project (i.e., the concessionaire and the highway agency) to accurately assess the effect of any increase in truck loading on the pavement performance and to decide on a fair compensation to be offered by the highway agency to the concessionaire, thereby contributing to the avoidance of dispute occurrence.

Methods and instrumentation for studying the strength of concrete joints in adhesive structures under the influence of operational and technological factors by the ultrasonic pulse method

The use of concrete adhesive joints in repair and restoration works is an effective technological solution from technical and economical point of view. To make such joints, polymer glues are used, for example, epoxy, siloxane, acrylic, etc. The use of such technology reduces material consumption, labour costs, and time of construction works. The analysis of published research results showed that the use of acrylic adhesives is effective. When performing an adhesive concrete joint, the main task is to ensure the required strength of the adhesive structure during its operation. The analysis of publications revealed that the strength of the structure is influenced by the following main factors: external load, strength of concrete to be glued, gluing area, and the thickness of the glue layer. Currently, the influence of the specified factors is being studied on samples of adhesive structures using mechanical, press equipment. During the experiments, external loads are applied to the manufactured sample of the adhesive structure, for example, tensile, bending or shear forces. The measured parameter is the strength of the adhesive structure. With such studies, it is difficult to determine the value of the maximum external load that leads to the formation of microcracks, which makes the strength of the structure reduce. As a result, this approach can cause an error in research conclusions, which will lead to a decrease in the reliability of operation of a real construction object. In addition, this approach makes it impossible to control the condition of those adhesive concrete structures that are used on real construction sites. The developed methods to study adhesive concrete structures using the ultrasonic pulse method are based on the dependence of the speed of propagation and attenuation coefficient of ultrasonic vibrations on the relative change in the structure of the material under consideration. The application of the developed methods and instrumentation for their implementation allows determining the value of the maximum permissible external load and ensuring the control of the state of adhesive structures in terms of crack formation on real construction sites.

Modeling of Aquatic Ecosystem Dynamics in a Run‐of‐River Reservoir in the Brazil

AbstractThe maximum specific pollutant loads of nutrients and carbonaceous organic matter of the effluent—in an initially oligotrophic or mesotrophic state artificial run‐of‐river reservoir—should be studied in order to serve as a basis for future hydroelectric in tropical regions. Two different hydrological scenarios in the central tropical region of Brazil are analyzed; a historical and a synthetic one. The maximum specific load that the artificial run‐of‐river reservoir of a hydroelectric power plant supports is evaluated in order to meet the environmental limits defined by national resolution. An analysis of lateral and vertical dispersion between epilimnion and hypolimnion is performed. The maximum permissible loads for the historical hydrological scenario with a long‐term average flow of 247.2 m3 s−1 are 70.017 kg BOD hm−3 d−1, 0.131 kg Ptotal hm−3 d−1, and 2.626 kg Ntotal hm−3 d−1. For the synthetic hydrological scenario with a long‐term average flow equaling 140.4 m3 s−1, the maximum permissible loads are 55.576 kg BOD hm−3 d−1, 0.096 kg Ptotal hm−3 d−1, and 1.925 kg Ntotal hm−3 d−1. The proposal of this study is to provide an aid to the decision‐making process of environmental managers and consultants in artificial run‐of‐river reservoirs in tropical regions with similar hydrological regimes.

Development and Analysis of an Innovative Layout Scheme of an Articulated Two-Section Tram Tramcar

Purpose. The main objective of the work is to develop and analyze the optimal layout of an articulated two-section tramcar for the creation of promising competitive models of cars of a significantly higher technical level, as well as to assess the prospects for their mass production provided that the maximum passenger capacity is ensured. Methodology. Based on the analysis of the regulated technical requirements for the dimensional parameters of tramcars, maneuverability parameters and permissible loads on their wheeled bogies, as well as on the analysis of the main technical parameters of existing models of single and two-section tramcars equipped with two biaxial wheeled bogies - body length and curb weight - the permissible length of their bodies and the estimated weight in the equipped state were determined. Two biaxial wheeled bogies were replaced by four uniaxial bogies. Findings. An innovative layout of an articulated two-section tramcar based on the use of four single-axle wheeled bogies and minimization of overhangs of body sections was proposed and developed, provided that the maximum length of a single tramcar and the track of wheeled bogies and the width of the car were preserved. A methodology has been developed for assessing the effectiveness of the proposed design solutions and the comfort of passenger transportation by single and two-section tramcars with two biaxial and four single-axial wheeled bogies, the preliminary designs of which have been developed according to three different layout schemes. Originality. For the first time, a layout of an articulated two-section tramcar is proposed based on an innovative solution - the use of four uniaxial wheeled bogies instead of two biaxial ones. A methodology for analyzing and evaluating the feasibility of using the proposed layout for creating promising models of a two-section tramcar has been developed. Practical value. The choice of an optimal innovative layout scheme with four uniaxial wheeled bogies for the creation of promising competitive models of articulated two-section tramcars with optimized parameters of their body length and nominal passenger capacity with higher passenger comfort compared to existing analog tramcars has been substantiated at the stage of developing draft proposals.

CAUSES AND METHODS OF FREEING DIFFERENTIAL PIPE STUCK

One of the actual problems of the oil industry is to keep production rates under control and not allow it to fluctuate. In this respect, all oil and gas production companies have their own course of action strategy to maintain the pace of oil production. There are many factors such as injection wells, well workover and drilling new wells that may influence to keep the process afloat. All these aforementioned methods have sophisticated and long-lasted ways to complete them. In addition, it should be pointed out that drilling wells has many wellbore challenges like differential pipe sticking. If bottom hole assembly and drill pipes cannot be freed as well as pulled out of the well without exceeding the maximum permissible load on the hook of the drilling rig, then it is assumed to be stuck. Keywords: pipe sticking, differential stuck, free pipe, drilling fluid, contact area, mud cake.

Analytical Model of Structural Damping in Friction Module of Shell Shock Absorber Connected to Spring

Vibration processes play a significant role in the modern industry. In most cases, vibration reduces strength, reliability, and durability of industrial machines, mechanisms, and structures, as well as adversely affects the health of support staff. This study presents a new dry friction shell shock absorber design. The shock absorber contains two spring sections and a friction module with an open shell and an elastic filler; at the same time, the spring sections and the friction module work in parallel. The proposed device demonstrates good damping characteristics, capable of operating under high operating loads, and at the same time has compact transverse dimensions. With a nonmonotonic loading of such a shock absorber, due to the contact interaction of the filler with an open shell, part of the energy that is supplied to the system will be dissipated. In other words, in response to the action of an external nonmonotonic loading, the phenomenon of structural hysteresis occurs in the friction module of the shock absorber. To describe the deformation of the shock absorber, a mechanical and mathematical model of a shell with a cut along the generatrix, which is the main bearing link, has been developed. By means of the technique of quasistatic analysis of structural damping in nonmobile nonconservative shell systems with a deformable filler, the hysteresis loops of the presented shock absorber are analytically described. Using them, according to the known loading history, it is possible to predict the behavior of the considered nonconservative system at any time after the start of the loading process. At each stage of the cyclic loading, the distribution of stresses and relationships between the external loading and the piston displacement was studied. Inequalities are obtained for permissible loads under which the operation of the shock absorber is safe. Such shell shock absorbers are projected to be used in the mining, oil and gas, and construction industries.

Effect of Controlled Rolling on the Structural and Phase Transformations

The development of ferrous metallurgy is mainly due to the requirements of the leading metal-consuming industries to improve the performance properties of structural steels to increase the permissible loads, to reduce metal consumption and to improve the reliability of machines, structures, main gas pipelines, etc. With significant volumes of rolled metal production, reducing energy consumption and consuming raw materials during its production also come to the fore. In this regard, important and relevant works are the works aimed at creating the fundamentals of metals science and the development of new technologies that allow manufacturing the products with the required combination of properties directly in the rolling mill stream (excluding subsequent heat treatment) by purposefully controlling the processes of structure formation, as well as expanding the areas of the practical application of such technological schemes (in terms of brand and size assortment, rental destination, etc.). Such an approach makes it possible to increase the competitiveness of metal products determined by the achieved combination of metal characteristics, while reducing the cost of its production.

Analisa Kekuatan Tali Baja Sling Crane Berkapasitas 40,6 Ton Di PT. Pelindo IV (Persero) Kendari

At the port usually the tools used as moving goods are container cranes, container cranes have the main component of steel rope slings which function as lifting cables on the hoist, usually chosen according to the needs of a construction for that it is necessary to analyze the strength of the steel rope slings currently used and comparing the steel rope with other types of steel rope in order to obtain a more comprehensive understanding of alternative steel rope selection that is appropriate for use in container/container lifting mechanisms. Research Objectives To analyze and determine the strength of a sling crane steel rope with a capacity of 40.6 tons and to determine the electrical power used. The research method is to make observations to determine the length of the steel rope using a roll meter and the diameter of the steel rope using a caliper. research, namely the calculation on wire rope obtained 3,896, kg, the cross-sectional area of the steel rope is 615.44 mm², the breaking stress is 6,330 kg/mm², the permissible breaking load of the steel rope is 12,150 kg, the tensile stress on the steel rope is 2,518 kg, the calculation on driving machine The resulting power (N) is 40.21 kW, the moment of static resistance on the motor shaft (M) is 239.927 kg.m.Keywords: Container, crane, steel rope, container

Calculation of Sustainability Indicators for Water Objects based on the Example of Water Use in the Arctic Basin of the Yenisei River

In the article, the fractal approach to the description of nonequilibrium water ecosystems in their exploitation conditions is considered. The article demonstrates clearly that, in these conditions, the management of the development of water objects should be a precautionary provision, which should furthermore be reduced to the management of potential anthropogenic risks arising from a violation of the coevolution of anthropogenic and natural processes equivalent to the disruption in sustainability of the ecosystem in its exploitation conditions. The fractal approach opens up new opportunities for the assessment of water management based on the calculation of the fractal sustainability indicator (anthropogenic transformation) for water ecosystems that is directly related to the maximum permissible environmental load (MPEL).

The rationality of using DNA diagnostics in sports cardiology

NGS is becoming an integral part of medical practice, including in cardiology. The role of genes in the formation of diseases of the cardiovascular system has been actively studied for the last 20 years. Currently, heart diseases with a hereditary component are usually divided into two large groups: monogenic syndromes that lead to an unfavorable outcome, including sudden cardiac death at a young age, and polygenic conditions that manifest after 35 years and are accompanied by deterioration in the quality of life. In professional sports, changes in the myocardium are almost inevitable, however, the first phenotypic signs of hereditary myocardial disease may be hidden behind adaptive changes, which are commonly called “athlete’s heart”. The carriage of causative genes radically changes the approach to the management of an athlete: his admission to training and competitive activities is reviewed, the volume of permissible load and the frequency of visits to a cardiologist are discussed. In this paper, we tried to identify clinical markers — «red flags» that would indicate the need for genetic testing on the example of athletes who underwent an in-depth medical examination in 2021–2022.

Effect of LED Lighting on Selected Quality Parameters of Electricity.

Recently, various technological light sources have appeared on the market. As a result, it is extremely important to evaluate the characteristics of the available lamps and the impact they may have on the power grid. This article presents regulations and standards for power quality, including higher current and voltage harmonics, and analyzes three selected light-emitting diode lamps. The purpose of the study was to analyze the impact of LED lighting systems on the power quality (PQ) of the electric grid. The results of measurements of parameters determining the power quality of the electricity consumed by modern LED light sources used for room lighting are presented. Commercially available lamps and low-power power supplies (25 to 35 W) with an output current of 350 mA were used for the study. The current waveforms of selected lamps during their connection to the power grid, the results of harmonic emission tests, as well as the effect of increasing the load of selected DC power supplies (drivers) on THD, power factor (PF), and their efficiency are presented. The significant negative impact of power supply circuits in compact LED lamps on the power quality parameters of lighting circuits was demonstrated. The tested lamps significantly exceed the permissible limits of harmonics and THD. Test results have shown that LED lamps show significant savings in electricity consumption, but they behave as nonlinear loads. They generate high-frequency current harmonics, which can lead to degradation of power quality in the distribution network. Therefore, if the primary concern for the user is power quality rather than power savings, traditional incandescent lamps would be a much better choice. When using switched-mode power supplies, attention should be paid to their load rating. You should avoid using power supplies in the lower ranges of permissible load capacity. A more heavily loaded power supply has better performance due to power quality and efficiency.

Gradeability of a Forwarder Based on Traction Performance

Based on the knowledge of the dimensional and mass features of a forwarder, a model was developed to assess its mobility during timber forwarding uphill in a safe and eco-efficient way. The model is based on knowledge of the position of the forwarder’s centre of gravity, its declared payload and the length of the loaded timber, as well as the gradeability for uphill timber forwarding based on the traction characteristics of the vehicle. The model connects two research approaches, (1) vehicle–terrain approach (distribution of axle loads depending on the longitudinal terrain slope) and (2) wheel–soil approach (estimation of the traction characteristics of the forwarder based on the wheel numeric), concerning previous research: (i) underload on the front axle of the vehicle, (ii) overload on the rear axle of the vehicle, (iii) permissible tire load, (iv) minimal soil bearing capacity, (v) wheel slip. Simulation modelling for the assessment of the forwarders’ mobility range during timber forwarding uphill was conducted on an example of an eight-wheel Komatsu 875 forwarder, with a declared payload of 16,000 kg, equipped with 710/45-26.5 tires, for which the position of the centre of gravity was determined by the method of lifting the axle. The results of the distribution of the adhesion load on the front and rear axles of the forwarder indicated that, during timber forwarding of 16,000 kg and 4.82 m long hardwood logs on a terrain slope below 68%, there is no critical unloading on the front bogie axle, nor overloading on the rear bogie axle, i.e., wheel tire overload that could limit forwarder mobility. For the specified range of longitudinal terrain slope, a minimal cone index of 950 kPa for an exemplary forwarder is an environmental factor and was calculated based on the nominal ground pressure of the reference (heavier loaded) rear wheels of the vehicle. The forwarders’ mobility range was determined by the intersection curves of the gradeability (based on forwarders’ traction characteristics at wheel slip of 25% vs. cone index) and the curve of the minimal soil cone index.

PLANNING THE CARGO OPERATIONS OF A BULK CARRIERWITH CONTINUOUS MAINTAINING ITS SEAWORTHINESS

The nautical safety of bulk carriers is largely determined by their correct loading. The available ship's instruments do not allow timely planning of loading operations and real-time control of the ship's condition during their execution. The ship's officers in charge have to spend a lot of time preparing the loading (unloading) plans. The high intensity of cargo operations at modern dry bulk terminals and the lack of sufficient time to prepare and verify the new cargo plan may create a risk of cargo holds being overloaded. This may lead to a deterioration of the local and longitudinal strength of the hull and a violation of the seaworthiness of the ship. The solution to this problem should be the development of new methods of cargo operations planning. Such methods should be based on a strategy of optimizing the distribution of a given quantity of bulk cargo, taking into account the availability of port facilities and the design of the vessel itself, its nautical parameters, stability, longitudinal and local strength. In order to achieve this objective, it is necessary to formalize the cargo operations in terms of a mathematical model of the ship and to establish the functional relationship between the parameters affecting the seaworthiness of the ship. Obviously, the development of this method is a promising area of scientific research aimed at improving the safety of bulk carriers.The article describes the method of loading operations of a bulk carrier with the task of choosing the best strategy for carrying out cargo operations according to the criterion of continuous seaworthiness of the vessel.Keywords: bulkcarrier, maritime safety, cargo operations, permissible loading, ship stability, the vessel strength, optimisation.

Reorganization of industrial zones into a comfortable urban environment

One of the main directions of scientific research on assessing the efficiency of the use of natural territories is a subject related to the development of scientific methods and approaches that provide not only the determination of the number of visitors, but also the active development of nature tourism. The development and education of nature tourism is one of the causes of recreational digression of natural-anthropogenic territorial complexes (hereinafter - PATC). Classifying the negative factors that cause the influence of anthropogenic impact on natural complexes and their consequences, we can distinguish three main types: mechanical, physical-chemical, biological. In the paper, special attention is paid to the condition of management and organization of recreational activities provided for at the PATK in Pushkino, which includes mandatory regulation and control of the number of visitors on the basis of the proposed regulations for the use of the relevant functional zones. On the territory of the Russian Federation in the normative documents established the need to determine the maximum permissible recreational loads (hereinafter - MPRN).

Экспериментальное исследование работоспособности газодинамического подшипника

The question of the high-speed turbo machines operability is directly related to the processes occurring in the support structures – gas sliding bearings. The most common structure of such supports is the multi-petal bearing. One of the main research directions in this area is the development of a design ensuring the reliable operation of the bearing. The durability of gas bearings depends directly on the number of start-stop cycles, which is its key difference from liquid bearings. The start-up period of the turbo machine represents the most challenging mode of operation for the petal gas dynamic bearings. A critical feature of this mode is the insufficient formation of a gas layer at low rotational speeds. The load on the working surfaces of the support is assessed as nominal, equal to the rotor's weight. If the start-up mode of the turbo machine is successfully passed, then in future, during the acceleration, it will be operational. The research of the transitional mode during the start-up requires a complex approach, including both theoretical and experimental studies. This paper is a continuation of theoretical studies for multi-petal gas dynamic bearings with overlapping petals. The key parameters ensuring the operability of such supports include the shaft ascent speed at the start-up and the value of the force acting on the support. As part of the research, an experimental installation was developed to obtain values of shaft ascent speed depending on static load force. Series of experiments included different variations of initial loads, up to the critical value. The results of the experiments provide the values of permissible static loads and a range of shaft ascent speed values. This study facilitates further parametric investigations in the mathematical modeling of processes occurring in gas dynamic bearings.

Еколого-економічне забезпечення рекреаційного лісокористування в умовах децентралізації: передумови, цілі та вимоги воєнного часу

It is defined that the factor of the presence of a large number of injured citizens of Ukraine as a result of Russian aggression requires the introduction of additional capacities in the recreational industry to ensure their recovery, in particular by means of psychological rehabilitation. It is revealed that, based on the existing natural and recreational potential of forest biogeocenoses, forestry of Ukraine has significant reserves for the development of recreational infrastructure. It is substantiated that due to the significant impact of recreational activities in forest biogeocenoses on the ecological sustainability of forest ecosystems, it is expedient to develop a system of ecological and economic provision for recreational forest management, taking into account the requirements of wartime and the consequences of deepening decentralization of power and local self-government reform. It is determined that a modern system of ecological and economic provision for recreational forest use should be based on taking into account information and digital, environmental-resource and institutional factors caused by corporatization of the forest sector of the national economy; digital transformation of the system of control over the economic development of forest resources potential; implementation of the basic provisions of international environmental conventions in the domestic practice of forestry. It is proved that an effective system of ecological and economic provision for recreational forest use in wartime conditions can be formed as a result of achieving the main, auxiliary and interim goals of forming a set of recreational and tourism products based on the development of the recreational value of forest biogeocenoses. It is found that in the spectrum of the main goals of ecological and economic provision for recreational forest management, the normalization of the tourist flow is of great importance, taking into account the maximum permissible recreational load on forest biogeocenoses to prevent manifestations of recreational digression. It is substantiated that the development of the infrastructure of recreational forest management and the expansion of the range of recreational services by permanent forest users will make it possible to ensure more efficient commercialization of protected objects that are in the use of forestry entities, thus allowing to increase the level of capitalization of forestry in different natural climatic zones.

Strength and deformation analysis of a welded truss under load in fire and emergency temperature conditions

Welded trusses are widely used in civil engineering due to the optimal combination of high manufacturability and the ability to operate in various force scenarios. During operation, such structures are exposed to a complex impact of various technological and accident factors. This makes it difficult to determine the key parameters necessary for the smooth operation of the farms during the planned period of operation. Under the simultaneous influence of force and high temperature factors on the truss structure, damage may occur in structural elements and their joints due to changes in the mechanical properties of the material, which can lead to structural failure. To identify the features of deformation and fracture of the welded truss, full-scale experimental studies were performed for the physical model at temperatures of 20°C, 200°C, and 450°C. A computer modeling experiment was also performed for similar parameters of the impact on the truss. Based on the results of the full-scale and computer modeling experiments, we generated deformation graphs that make it possible to study the strength and deformability of the loaded welded truss at fire and emergency temperatures. A series of graphical dependencies characterizing the strength and deformability of the truss when it is loaded at different temperatures has been constructed. An analytical dependence has been developed that makes it possible to determine the value of the maximum permissible load on the truss at temperatures up to 450°C based on the known value of this load for room temperature conditions with a coincidence of 97.5...98.3%. It is advisable to use the obtained dependence (graphical or analytical) when designing or operating trusses to determine the maximum permissible loads on the structure at elevated temperatures.