Investigation of the relationship between the strength limit and the long time fatigue of steel reinforcements of reinforced concrete structures

The results of experimental studies have shown a strong effect of diffusion hydrogen on the static and cyclic parameters of crack resistance of reinforcing steel. It was found that with increasing flooding, especially when the hydrogen content exceeds 5 cm3/100g, both static strength and long-term strength (fatigue) decrease sharply. Moreover, these areas of hydrogen solution in reinforcing steel are characterized by a viscous nature of fracture, while for heavily flooded reinforcement (from 5 to 12 cm3/100g) is characterized by brittle fracture by the mechanism of microcracking in the hardened (martensite or troostite structure). The analysis of the obtained experimental results allowed to determine the optimal hydrogen content in the reinforcing steel (3…5 cm3/100g), the excess of which can cause a decrease in the crack resistance of the reinforcement during long-term operation, especially in corrosive environments. The mechanism of hydrogen influence on crack resistance of metal at static and alternating loading which consists in diffusion and dislocation movement of hydrogen in structure of a reinforcing core that as a result that causes strong flooding of steel and its embrittlement is offered. It is established that carbon and low-alloy sieves, which are characterized by ferritic-pearlitic and sorbitol structure provide high resistance, especially to long-term fatigue, and the transition to steels with a structure of martensite or tempered (transient structure of bainite) structure of bainite sharply reduces reinforcing steel, which makes it impossible to use in the manufacture of reinforcement involved in reinforced concrete structures designed for long-term operation (more than 50…60 years). Thus, the obtained diagram can be recommended to designers of reinforced concrete structures for hydraulic purposes, as it greatly facilitates the reasonable choice of reinforcement in the development of reinforced concrete structures for responsible and long-term use.

The twentieth century science paradoxes

The isolation of hypothetical theories from the realities of living matter has caused mysticism to penetrate scientific theories. With mystical thinking, the idea of using an analytical method to solve cognitive problems does not occur. Dialectical logic, in contrast to mysticism, states the opposite: any problematic tasks of cognizing the vital processes and phenomena of the universe are solvable exclusively in an analytic way, with the only method. The author created a universal and formal theory of solving intellectual (i.e., having no previously known algorithms for solving) problems associated with the knowledge of the vital functions of natural and man-made processes in any phenomena of the universe - the Kondratenko method of axiomatic modeling, the effectiveness of which is achieved by correctly setting the problem and solving it purely formal method. The correctness of the statement of the problem means, first of all, the recognition of the failure of all hypothetical (not confirmed by the results of full-scale experimentation with the subject of knowledge) theories. This requirement, in particular, to the mathematical tools used to solve problems of cognition, it revealed paradoxes in the foundations of mathematics, which are discussed in the article. At present, in the natural and applied sciences in most publications, i.e. more than 90% associated with the construction of formal theories in these sciences, the proof of theorems is carried out: firstly, in a meaningful way, which contradicts the urgent requirement of philosophers of science to use exclusively formal evidence, which is a criterion for assessing the correctness and reliability of evidence; secondly, in substantive evidence in 95% of cases, an exclusively standard list of tautologies is used, which by definition is incorrect for the purpose of proving theorems on phenomena and processes of the universe based on exclusively true axioms obtained as a result of full-scale experimentation with these phenomena and processes. The article deals with the paradox in the classical approach to proving theorems, which consists in the inappropriateness of generally accepted stereotypical tautologies of classical mathematics for proving theorems.

One approach to the axisymmetric problem of impact of fine shells of the S.P. Timoshenko type on elastic half-space

Refined model of S.P. Timoshenko makes it possible to consider the shear and the inertia rotation of the transverse section of the shell. Disturbances spread in the shells of S.P. Timoshenko type with finite speed. Therefore, to study the dynamics of propagation of wave processes in the fine shells of S.P. Timoshenko type is an important aspect as well as it is important to investigate a wave processes of the impact, shock in elastic foundation in which a striker is penetrating. The method of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind and the convergence of this solution are well studied. Such approach has been successfully used for cases of the investigation of problems of the impact a hard bodies and an elastic fine shells of the Kirchhoff-Love type on elastic a half-space and a layer. In this paper an attempt is made to solve the axisymmetric problem of the impact of an elastic fine spheric shell of the S.P. Timoshenko type on an elastic half-space using the method of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind. It is shown that this approach is not acceptable for investigated in this paper axisymmetric problem. The discretization using the Gregory methods for numerical integration and Adams for solving the Cauchy problem of the reduced infinite system of Volterra equations of the second kind results in a poorly defined system of linear algebraic equations: as the size of reduction increases the determinant of such a system to aim at infinity. This technique does not allow to solve plane and axisymmetric problems of dynamics for fine shells of the S.P. Timoshenko type and elastic bodies. This shows the limitations of this approach and leads to the feasibility of developing other mathematical approaches and models. It should be noted that to calibrate the computational process in the elastoplastic formulation at the elastic stage, it is convenient and expedient to use the technique of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind.

Synthesis of Arts in Soviet Architecture: stages of development, main directions, causes of their occurrence

The history of the Soviet Union, its socio-economic, socio-political and socio-cultural life is unique in comparison with other countries. The USSR was created on the model of social development, expressed by European and Russian Utopian socialists and was grounded in the classics of Marxism-Leninism. So, the system of government, economic conditions and cultural activities of a society built on the hegemony of the proletariat was a long-running social experiment that conditioned the life of the Soviet people and influenced other countries as well. The experiment of a country with total state property envisaged that the party leadership assumed responsibility for defining all spheres of political life - both internal and interstate relations - and inevitably formed unified programs of cultural activity and social development, managed them, and financed and tightly controlled their implementation. The Soviet people, the so-called "working masses", were forced to live and act under uniform rules. Depending on the planning of the political, economic and social life of the party leadership throughout the existence of the USSR, the country went through several stages, which differed in the directions of forming an architectural and urban planning environment that had to meet the tasks of state and ideological character. Familiarizing yourself with this unique experience and finding the reasons for its formation is important for understanding the trends of social development in the twentieth century.

Improvement of the calculation and experimental method of evaluation of carbonization of reinforced concrete structures of sewerage underground systems

Carbonization of concrete leads to a decrease in the alkalinity of concrete, an increase in the number of hydrogen ions in the pores, is one of the main factors that lead to corrosion of reinforcement, the formation of cracks and the subsequent reduction of load-bearing capacity of structures. The study of the depth of carbonization of concrete is to determine the pH of the pore liquid at different depths. There are devices with automatic maintenance of a given concentration of carbon dioxide, to determine the diffusion permeability of concrete to carbon dioxide, based on data on the rate of neutralization (carbonization) of concrete with carbon dioxide. Basically, this method is intended for use in the development of technology and design of concrete composition, providing long-term maintenance of structures in non-aggressive and aggressive gaseous environments, as chips are not prepared immediately before the test and after reaching the design age are placed in the installation with reagents for 7 days. But to determine the carbonization directly on the construction site or object often use the pH method, i.e. the indicator method of pH determination. To assess the concentration of hydrogen ions used acid-base indicators - organic substances – dyes, the color of which depends on the pH from the obtained results the algorithm of definition of depth of carbonization consists in the following actions. The improved formula of definition of depth of carbonization of concrete taking into account degree of aging and corrosion damages for what in the final formula the corresponding coefficients kst and kkor are entered: hcarb = {(2D˖C˖τ) / (mo˖kst ˖kkor)} 1/2, where the effective diffusion coefficient of CO2 in the concrete of the existing reinforced concrete structure, which is determined by the condition D = (mo˖δ2) / (2C˖t ). The thickness of the neutralized layer δ is determined experimentally on an existing structure using a physicochemical method (phenolphthalein solution or using depth gauges. .Concentration of CO2 in air C should be determined by chemical analysis of air samples taken directly from the structure or take ≈ 0.03%. Re. the ability of concrete mo is determined by the formula mo = 0.4 (C˖p˖f), taking the amount of cement, kg per 1m3, respectively, the strength of concrete. neutralization of concrete is equal to f = 0.5.

Formation of the architectural space of health care facilities based on landscape design

Architecture is gradually changing along with the development of society, its changing perceptions of beauty, strength, usefulness, as well as the growing need for comfort, aesthetics, the ideal environment. For a long time, the architecture of health care facilities was perceived and, accordingly, mechanically designed exclusively as a kind of technically necessary shell to ensure the treatment of the impersonal mass of the population. This approach was due to the acute and rapid need for a quantitative supply of medical institutions to a large number of people in large areas. This is what happened in the last century in the post-Soviet countries - standard projects of medical institutions were "cloned" everywhere, which were integrated into the urban environment by huge industrial-panel arrays without regional, cultural and aesthetic connection with "genius loci" and urban context. Do we have the right to condemn this large-scale approach that prevailed in the twentieth century? No. At one time, he made it possible to resolve the important issues of providing medical care to the majority of the population of the Soviet Union. Thanks to the massive and economic industrial design and construction approach, Ukraine has received an extensive urban network of various health care facilities, which continue to perform their functions, accepting the harsh challenges and trials of global pandemics and epidemics. The main problem is that with the acquisition of sovereignty in Ukraine began protracted political-oligarchic clan "internecine wars", which for decades froze attention to improving, modernizing, updating and developing the architecture of health care facilities. A significant part of Ukrainian hospitals is in a condition that not only does not meet sanitary and other requirements, but even threatens the health and lives of patients and staff. But it is not customary to talk about it. The Soviet mentality, enshrined in our subconscious, forces everyone in their place to report on the order, on compliance, on the implementation of plans. Despite the long-standing disregard for the problems and issues of compliance of domestic medical architecture with world standards, the powerful and once the world's best "machine" continued to perform its functions, inertially moving down from its pedestal. But today, in 2021, we are frantically approaching the foot of the new "rock", which embodies all the latest advances in health care and which the world's leading countries have gradually, step by step, overcome with long-term state plan for the development of medicine and with periodic reforms in the medical field.

Development of cross-platform applications

The work is devoted to the study of cross-platform development of applications, elements of architecture, tools, programming languages and frameworks. During the work, the existing development tools were considered, one framework was studied in detail, which is currently the only one of its kind today. Developed recommendations for creating applications.

Reinforcement of metal structures by external reinforcement by gluing high-strength fiber-reinforced systems: analytical approach

Ukraine's construction heritage includes numerous examples of the use of metal structures, especially those used in industrial buildings and high-span structures. The use of metal structures in construction is due primarily to their mechanical properties. They are frost-resistant and can withstand temperatures down to -65 degrees, hard, durable, strong and reliable. They can also be used in areas with high seismic activity. But, as in the case of other types of structures, there is a need to restore or strengthen metal structures due to structural defects, wear of load-bearing elements, as well as to increase the load-bearing capacity. In some cases, reinforcement with fiber-reinforced polymer composites (FRP) gives a better result compared to traditional methods of reinforcement using metal

Stochastic model and method of optimization of operating modes groups of artesian wells in water supply systems

Water supply of large cities is carried out, as a rule, from open reservoirs - lakes, reservoirs, large rivers, ie from sources with significant water reserves. In this case, the water supply scheme includes: pumping stations of the first rise, which take water directly from the water; water treatment system (purification); pumping stations of the second and third rise, pumping clean water over long distances and supplying it to settlements [1]. If the settlement is located in an area where there are no large open water sources, or the geographical location of the settlement allows the use of groundwater, in which case artesian wells are used as a source of water supply. Usually small settlements are supplied with water from artesian wells. Artesian wells are widely used for water supply of villages, industrial water supply, for irrigation (irrigation systems), in the mining industry, to reduce the level of groundwater. The advantage of using artesian wells to supply the population with drinking water is that the water is extracted from great depths and purified using natural filters [2]. Thus, the cost of water treatment is significantly reduced. The disadvantage of using artesian wells is usually low productivity of the well, the strong dependence of water volumes in the well on climatic and weather conditions, depletion of the well as a result of large-scale construction or extraction of natural minerals such as shale gas [3].

Aspekty medyczno-prawne dotyczące żywienia w kontekście bezpieczeństwa ekologicznego żywności

They know better all the features and risks of their business, and therefore they must be responsible for their safety. Implementation of the main elements of the new food safety control system in Ukraine takes place through the implementation of a permanent procedure based on the HACCP principles [1−3]. Now, entrepreneurs must identify potential hazards and risks of the production process and capacities, as well as take all necessary measures to minimize them. Together with greater responsibility the entrepreneurs receive more freedom. For example, the state cannot require the factory to have light walls above 1.8m. The quality is a subjective and personal concept, and safety requirements must prevent the harmful effects of products on the health of the consumer. At the same time, Ukrainians need to know what they are consuming. Therefore, lawmakers are currently working on a draft law on providing information to consumers about food. The new system to which Ukraine passes allows a clear distinction to be drawn between liabilities for causing harm due to the consumption of a dangerous product. According to the concept of the food chain «from the lawn to the table», the quality of the product must be baked at each stage of the commodity circulation, and each businessman is responsible for the safety of the food within its activities: the manufacturer − within the limits of production, the carrier − within the scope of transportation, the store − within storage and sale. Consequently, at each point of the food chain, the entrepreneur knows where the raw material or product came from and where it comes next. If the customer receives a health hazard product, this system helps to identify: who is responsible for causing harm. In this chain, there should be feed for productive animals. The draft law «On Safety and Hygiene of Forms» has already been developed and registered. If the feed contains harmful substances, they will continue to enter our body through products made from animal meat.