https://sci.ldubgd.edu.ua/jspui/handle/123456789/13591 2026-04-07T04:18:59Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/15218 Title: УСТАНОВКА ДЛЯ ВИЗНАЧЕННЯ ВОГНЕЗАХИСНОЇ ЗДАТНОСТІ (ЕФЕКТИВНОСТІ) ВОГНЕЗАХИСНИХ ПОКРИТТІВ ТА ВИПРОБУВАНЬ НА ВОГНЕСТІЙКІСТЬ МАЛОГАБАРИТНИХ ФРАГМЕНТІВ БУДІВЕЛЬНИХ КОНСТРУКЦІЙ Authors: Веселівський, Роман Богданович; Ковалишин, Василь Васильович 2024-12-13T00:00:00Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/15058 Title: Identifying the evolution of through cracks in iron-reinforced hollow slabs under the influence of a standard fire temperature mode Authors: Sidnei, Stanislav; Myroshnyk, Oleh; Kovalov, Andrii; Veselivskyi, Roman; Hryhorenko, Kostiantyn; Shnal, Taras; Matsyk, Ihor Abstract: The object of this study is the fire resistance of reinforced concrete hollow slabs at the onset of the limit state of loss of integrity. The problem of accurate modeling of the formation and development of cracks in concrete was investigated. The paper reports an analysis of the results of the stress-strain state of a reinforced concrete hollow slab during fire exposure for devising a method for evaluating the fire resistance of such structures upon the onset of the limit state of loss of integrity. According to EN 1992-1-2, the determination of fire resistance of structures is provided by calculation methods, however, there is no such procedure for reinforced concrete hollow slabs. Many scientific works offer refined methods for evaluating only the loss of load-bearing and heat-insulating capabilities, leaving aside the issue of loss of integrity. Thus, this can lead to a biased evaluation of reinforced concrete hollow floor slabs according to the criterion of the limit state of loss of integrity, which in turn can put under a threat to the fire safety of buildings, which threatens the life and health of people. According to the results of the calculation, a parameter has been determined, according to which the onset of the limit state of fire resistance, in particular, the loss of integrity, was established. Summarizing the damage distributions, it was assumed that in the case of reaching the critical plastic deformation of 2.5e-3 in concrete finite elements, they are excluded from the general set of finite elements. Thus, in the case of the formation of through cracks, the removal of finite elements is taken as a parameter to identify the onset of the limit state of loss of integrity. According to the results of the computational experiment, it was established that through cracks in a fragment of a reinforced concrete hollow slab are formed in 44 min. According to the results of the research, the method of evaluating the fire resistance of such structures based on the onset of the limit state of loss of integrity has been substantiated. Such a method could be applied during design, which provides an opportunity to determine the limit of fire resistance in reinforced concrete hollow slabs 2024-08-29T00:00:00Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/13888 Title: ОБҐРУНТУВАННЯ ТЕХНОЛОГІЇ ГАСІННЯ КОМБІНОВАНИХ ПОЖЕЖ ЗА НАЯВНОСТІ ЛЕГКИХ МЕТАЛІВ ЧИ ФОСФОРНИХ СПОЛУК Authors: Ковалишин, Василь Васильович; Марич, Володимир Михайлович; Веселівський, Роман Богданович; Ковалишин, Володимир Васильович; Лозинський, Роман Якович Abstract: Formulation of the problem. During Russia's armed aggression on the territory of Ukraine, cases of combined fires in the presence of light metals or phosphorus compounds, accompanied by high combustion temperatures and the release of toxic combustion products, have been repeatedly recorded. Given the danger of these fires, it is important to quickly localise and eliminate them. The analysis of scientific papers on effective extinguishing agents and methods of their supply has revealed the absence of a single approach and algorithm for extinguishing these fires. Accordingly, the substantiation of the technology for extinguishing combined fires in the presence of light metals or phosphorus compounds and the study of the effect of the thickness of the extinguishing powder layer on the combustion and cooling temperature of magnesium is an urgent scientific and technical task. The aim of the work is to improve the technology for extinguishing combined fires in the presence of light metals or phosphorus compounds and to study the effect of the thickness of the extinguishing powder layer on the combustion and cooling temperature of magnesium. Research methods. A comprehensive method was used to conduct the study, which includes: the analysis and application of statistical data processing methods and a comprehensive method of fire research. To study the effectiveness of cooling during the process of extinguishing magnesium alloy cinders, a methodology was used to determine the required amount of fire extinguishing powder to achieve an insulating effect. The main results of the study. For effective extinguishing of class D fires, it is necessary to study the thermal characteristics of fire extinguishing powders in the conditions of extinguishing magnesium alloy fires. The thermal insulation ability of fire extinguishing powders based on sodium chloride, ground slag, ammophos, aerosil, and zinc stearate was experimentally investigated. The effect of the thickness of the fire extinguishing powder layer on the combustion and cooling temperature of magnesium was determined. The dependence of the temperature at the metal/powder interface and the temperature at the air/powder interface on the thickness of the layer applied by the fire extinguishing powder was determined. Based on the experimental temperature values obtained, the coefficient of thermal conductivity and heat capacity of the fire extinguishing powder was determined and the required thickness of the powder layer was calculated to ensure thermal insulation of the burning centre of magnesium alloy shavings. The required thickness of the fire extinguishing powder layer, which will ensure a safe temperature for humans at the border with an air of 80 0C, is 24 mm. For effective extinguishing of combined fires at the initial stage of development, it is necessary to use a powder-foam extinguishing unit with a nozzle-soothing agent. Conclusions. The influence of the thickness of the extinguishing powder layer on the temperature of magnesium combustion and cooling was experimentally investigated. The required thickness of the layer of extinguishing powder based on sodium chloride, ground slag, ammophos, aerosil, and zinc stearate ( = 24 mm) to achieve a safe temperature for humans at the border with an air of (80 °C) was determined. Recommendations for extinguishing light metals or phosphorus compounds have been developed and the basic requirements for occupational safety when working with extinguishing powders and foams/extended life foams have been formulated. Keywords: light metals, phosphorus compounds, magnesium alloy, extinguishing efficiency, occupational safety, fire extinguishing agents. 2024-06-28T00:00:00Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/13887 Title: Environmentally safe installation for determining the fire resistance of coatings and fire resistance tests of small fragments building structures Authors: Veselivskyi, Roman; Yakovchuk, Roman; Petrovskyi, Vitalii; Havrys, Andrii; Smolyak, Dmytro; Kahitin, Oleksandr Abstract: Actuality. Taking into account fire statistics, the task of preventing the occurrence and spread of fires is urgent. It is obvious that the fire resistance of building structures, which must be taken into account at the design stage, is of the greatest importance and influence on the development and spread of fires in buildings and structures. Conducting fire experiments makes it possible to obtain the most complete information about the behavior of building structures under fire effects, however, the scale of field tests, labor-intensiveness, energy consumption and damage to the environment prompts the search and development of alternative methods that would ensure the environmental friendliness of the tests, compliance with the conditions of the experiment ( standard fire temperature regime), and at the same time would make it possible to estimate the limit of fire resistance of a building structure in reduced dimensions or to experimentally determine the fire-resistant ability (efficiency) of fire-resistant coatings. Purpose. The main goal of the article is rationale use of an installation for determining the fire-resistant capacity (efficiency) of fire-resistant coatings and fire resistance tests of small-sized fragments of building structures, taking into account the reduction of the harmful load on the environment. Main results. Research has been carried out and the design features of the installation have been substantiated, the principle of which is to heat the inner space of the chamber with the help of electric heating elements, which, unlike liquid fuel (diesel fuel, fuel oil, gas), do not harm the environment. A control unit-module of variable voltage regulation designed to regulate the heating temperature of the radiation panel in the test chamber has been developed. The design of the created test setup makes it possible to increase or decrease the temperature on the heating surface of the test sample, not only with the help of the heating temperature regulator, but also in manual mode, by moving the test sample closer or further away from the radiation panel along the guides. Conclusions. According to the results of experimental tests, it was established that the chamber of the installation warms up uniformly and according to the standardized temperature-time dependence Ts = 345lg (8t+1)+20). At the same time, the temperature regulation process using BP-10 with triac output ensures stable operation of electric heating elements up to temperatures of 1000 °C. A feature of the created installation is the possibility of additional lowering or raising of the temperature on the heating surface of the experimental sample, in case of its deviation during the experiment, by means of approaching or moving away from the sample to the heating panel. The conducted studies confirm the necessary reproducibility of experimental results. 2024-04-17T00:00:00Z