ALGORITHM FOR SELECTING THE OPTIMAL THICKNESS OF FIRE PROTECTIVE COATINGS FOR METAL STRUCTURES

A comprehensive computational and experimental method for determining the optimal thickness of fire-protective intumescent coatings for steel building structures is presented. The development of this method was driven by a pressing design challenge: the impossibility of applying standard computational approaches to intumescent coatings due to abrupt changes in their thermophysical properties during thermal decomposition and complex physicochemical transformations under high-temperature conditions. The proposed algorithm integrates data from synchronous thermal analysis, which allows for the study of degradation stages and thermal effects of the material, the results of full-scale fire tests of coated specimens under standard temperature conditions, and subsequent numerical modeling of the transient thermal field using the Elcut software package. Based on the experimental data, highly accurate regression polynomial models were obtained for key parameters – the heat capacity and thermal conductivity of the coating as a function of temperature. Verification of the method on a real structure (a 20B1 I-beam) showed that the discrepancy between the calculated and experimental heating times to the critical temperature (500 °C) does not exceed 10 %. The obtained results demonstrate the practical value of the method as an effective alternative to expensive and time-consuming full-scale fire tests at the fire protection design stage.