This paper reports a study into the possibility of applying a simplified approach, recommended by standards for conventional steel beams, to determine the heating temperature under the conditions of a fire in relation to steel I-beams with a corrugated wall. The research is predetermined by the limitation of methods that make it possible to determine the heating temperature of this type of beam in a fire using engineering methods with a small amount of calculations. Technical data on steel beams with cladding have been considered for calculation, the features of heat impact of fire on them have been analyzed, a calculation procedure has been devised, the estimation schemes have been built, and the calculations have been performed. Data on the temperature distribution in the cross-sections of beams with and without cladding were obtained by using a simplified method recommended by standards and the refined method based on a finite-element method. Mathematical models have been constructed for calculations that describe the effect of a standard temperature regime of fire on the distribution of temperature in each minute in the cross-sections of steel beams with and without cladding. The models have been described on the basis of the differential equation of thermal conductivity, boundary conditions of the third kind, which take into consideration convective and radiant heat transfer. It was established that the mineral wool cladding of the beam with a corrugated wall is a reliable fire protection agent. The heating temperature of the beam does not reach a critical value of 500 °C in 60 minutes, which provides the class of this beam with the most stringent requirements for its fire resistance in accordance with the classification in line with the acting norms in Ukraine. The simplified method, recommended by the current standards of the European Union and Ukraine, could be effectively used to analyze the fire resistance of these beams and is the basis of the procedure for the estimated assessment of the fire resistance of these structures

The existing means for calculating the fire resistance of steel reinforced concrete horizontal structures beyond the fire resistance limit for more than two hours have been studied. There were conducted the computational experiments on the analysis of thermal load in case of fire for up to 3 hours, without taking into account the mechanical load on steel reinforced concrete slabs, modeled using steel sheets. The indicators obtained as a result of thermal computational experiments provide an opportunity to analyze the temperature distribution in the thickness of steel reinforced concrete horizontal structures made with a steel sheet. The relevant results can be used to determine the indicators of fire resistance of these structures for at least 3 hours. Thus, the thermal dependences, studied in this work, are a scientific basis for improving the capabilities of existing methods for determining the fire resistance of steel reinforced concrete horizontal structures with a steel sheet. The process of determining the temperature distribution indicators in these structures was performed using the standard method for solving the equations of thermal conductivity using the finite element method. Based on the results of solving the thermal problem, the graphs of thermal dependences were constructed, providing an opportunity to further analyze the indicators of fire resistance on the basis of the onset of signs of loss of load-bearing and insulating capacity. In order to perform computational experiments, the necessary calculation models were built that take into account the thermal effect on the studied structures under the standard temperature mode of fire.

No abstract

The issue related to the conditions for creating the required temperature regime of fire when testing structures for fire resistance has not been studied in detail up to now. That necessitated determining the technical conditions under which it is possible to comply with the standard temperature regime of fire in the fire chamber of the furnace. The influence of the design parameters of the fire furnace chamber on the condition of compliance with the standard fire temperature regime when tested for fire resistance has been established. One of the most effective methods for examining such an impact is computer simulation. A computer model of the fire furnace was built on the basis of a comprehensive analysis and earlier work on the study of such furnaces, taking into consideration technical characteristics, in particular, geometrical parameters, fuel and air supply systems. The obtained research results are a prerequisite for scientific substantiation of the design parameters of fire furnaces and their engineering systems, which is necessary to comply with the standard temperature regime of fire in the furnace fire chamber. This makes it possible to provide the necessary conditions for testing building structures for fire resistance in compliance with the requirements of the relevant standards. The computer model constructed makes it possible to create the necessary temperature regime in the fire chamber of the furnace (in this study, the standard temperature of fire). As a result of the study, the technical parameters of the fuel supply and ventilation system were determined, which ensure compliance with the standard temperature regime in the fire chamber of the furnace. That makes it possible to build an automated complex of the testing process for fire resistance of building structures. In addition, the data obtained can be the basis for the design of such fire furnaces with the ability to comply with different fire temperature regimes without the intervention of the operator.

Показано недоліки підходу щодо формування захисних властивостей захисних споруд цивільного захисту та критеріїв, які їх зумовлюють. Проаналізовано статистичні дані щодо функціонування таких споруд в Україні та стан захищеності населення на одну тисячу осіб. Надано статистику щодо пошкоджень будівель та споруд на території нашої країни внаслідок бойових дій. Крім того, наведено дані, які характеризують рівень таких пошкоджень, а також щодо соціальних втрат населення, яке перебувало у будівлях та спорудах, що зазнали пошкоджень під час війни. Проаналізовано поведінку огороджувальних будівельних конструкцій захисних споруд та укриттів в умовах впливів вибухів і механічних імпульсних дій бойових засобів, спричинених повітряними та артилерійськими обстрілами. Окреслено залежність середніх значень соціальних втрат населення від кількості прямих влучань снарядів у будівлі та споруди. Проведено аналіз нормованих в Україні критеріїв, які визначають захисні властивості захисних споруд цивільного захисту. Запропоновано удосконалений перелік таких критеріїв та методику щодо їх визначення залежно від конструктивних параметрів захисних споруд цивільного захисту. Результати роботи стануть передумовою для подальших досліджень щодо обґрунтування конструктивних параметрів приміщень безпеки житлових і громадських будівель в умовах воєнного стану та використовуватимуться проєктними організаціями й наглядовими органами під час проєктування та оцінювання ефективності функціонування захисних споруд цивільного захисту. Визначено актуальні завдання для подальших наукових досліджень у напрямі підвищення захисту цивільного населення від уражень під час бойових дій за допомогою запропонованих критеріїв та методів