THE RATIO BETWEEN THE VALUES OF THE REQUIRED MINIMUM THICKNESS OF FIRE PROTECTION COATINGS FOR STEEL STRUCTURES FOR DIFFERENT NOMINAL FIRE TEMPERATURE-TIME CURVES

Abstract

Insufficient certainty of the relationship between the values of the required minimum thickness of fire protection coatings for steel structures at different nominal fire temperature-time curves necessitates research aimed at assessing this thickness for coatings made of reactive and passive fire protection materials under fire exposure conditions specified in EN 1363-2 and differing from the standard ones. The study aimed to determine the ratio between the values of the required minimum thickness of a reactive fire protection coating of a certain brand for the temperature-time curves of hydrocarbon and external fires in accordance with EN 1363-2 and the standard temperature-time curve in accordance with EN 1363-1 for steel structures with a wide range of changes in their parameters. According to the method, which is based on the provisions of EN 13381-8 and DSTU B V.1.1-17, the ratio (difference) between the values of the required minimum thickness of the reactive fire protection coating of the Endotherm 400202 trademark at different nominal fire temperature-time curves for steel structures with the following parameters was determined: cross-sectional area ratio from 40 m^-1 to 300 m^-1, critical temperature from 350 °C to 700 °C and fire resistance retention time from 30 min to 60 min. It is determined that the value of this difference, depending on the parameters of the steel structure, varies from 79 % to 874 % under the temperature regime of a hydrocarbon temperature-time curve, and from 6 % to 39 % under the temperature-time curve of an external fire. For both the conditions of fire exposure under the temperature-time curves of a hydrocarbon fire and an external fire, the difference decreases with an increase in the cross-sectional coefficient and a decrease in the critical temperature and significantly depends on the fire resistance retention time of the steel structure. It is shown that it is natural to decrease the value of the difference with an increase in the fire resistance retention time at the
temperature-time curve of a hydrocarbon fire and its increase at the temperature-time curve of an external fire.