ASSESSMENT OF THE REQUIRED THICKNESS OF FIRE PROTECTION OF STEEL STRUCTURES UNDER CONDITIONAL FIRE SCENARIOS

Abstract

Given the practical significance and lack of certainty of data on the parameters of fire protection systems for steel structures under nominal fire temperature regimes that differ from the standard temperature regime, research aimed at improving and developing methods for assessing the required fire protection thickness of these structures under various conditional fire scenarios is relevant. The conducted study aimed to determine the analytical dependences of the ratio of the values of the required thickness of the fire protection coating for scenarios of a conditional fire under the temperature regimes of hydrocarbon and external fires and its values under the standard temperature regime on the parameters of the steel structure, which are acceptable for engineering calculations. A research method was applied, the components of which are procedures for numerical modelling of the thermal state of a steel structure under conditional fire scenarios, approximation of the obtained calculated data using regression models, and comparison of calculated values with experimental ones. According to the results of the study, the relationship between the values of the required thickness of the fireproof coating under different scenarios of a conditional fire for different values of the coefficient of thermal conductivity and specific volumetric heat capacity of the fire protection coating, the cross-sectional area coefficient, the critical temperature, and the time interval for maintaining the fire resistance of the steel structure was determined. The influence of steel structure parameters on this ratio has been determined. The obtained calculated data were approximated with respect to the indicated ratios using two linear regression equations (for the scenario with the temperature regime of a hydrocarbon fire and for the scenario with the temperature regime of an external fire). It is shown that the obtained analytical dependencies (regression models) based on the values of the coefficient of determination and Fisher's exact tests are qualitative and adequate. It was established that the obtained analytical dependencies are acceptable for engineering calculations regarding the prediction of the required thickness of passive and reactive fire protection coatings of steel structures for conditional fire scenarios under the temperature regimes of hydrocarbon and external fires.