EVALUATION OF THERMAL PROPERTIES OF REACTIVE FIRE PROTECTIVE COATINGS FOR STEEL STRUCTURES

Abstract

Mathematical models of thermophysical properties of intumescent fire-retardant coating, used in the procedure for determining such properties, are described in EN 13381-8 or DSTU B V.1.1-17. These models do not fully take into account the peculiarities of thermal conductivity in such a coating under fire conditions. This can lead to significant discrepancies in determining the thickness of a coating required to ensure normalized fire resistance rates for steel structures (columns and beams). The aim of current study was to improve the existing procedure for determining thermophysical properties of intumescent fire-retardant coating by applying an updated model.

Based on the results of the study, a modified procedure for determining thermophysical properties of intumescent coatings, designed for fire protection of steel structures, was developed. The initial data for this procedure are the temperatures in the furnace and steel for unloaded short structures, obtained during tests according to EN 13381-8 or DSTU B V.1.1-17 using standard time-temperature curve.

The study substantiates the use of an updated model, which takes into account the dependence of thermal conductivity of such fire-retardant coating on temperature, initial coating thickness and cross-sectional coefficient of steel structure, in this procedure. A piecewise linear dependence of thermal conductivity of a coating on temperature was introduced. The dependence of thermal conductivity coefficient on coating thickness and cross-sectional coefficient is determined by the linear regression equations. This modified procedure also determines the algorithm for calculating thermophysical properties of intumescent fire-retardant coating. The directions for further studies were suggested, focusing on the estimation of reliability of results received when the developed modified procedure is applied.