CALCULATION-EXPERIMENTAL METHOD ASSESSMENT OF FIRE RESISTANCE OF FIRE-PROTECTED STEEL STRUCTURES

The article improves the mathematical model for assessingthe fire resistance of fire-protected steel structures by taking into account the thermophysical characteristics of fire-protective coatings.For the first time, the patterns of influence of the thickness, thermal conductivity coefficient and density of the fire-retardant coating on the value of the fire resistance limit of fire-protected steel structures were revealed,which was time, using the method of multifactorial experiment planning.A computational and experimental method for assessing the fire resistance of fire-protected steel structures has been developed. A control algorithm and procedure for implementing the developed computational-experimental method for assessing the fire resistance of fire-protected steel structures have been developed, which is based on experimental (test unit) and computational (modeling unit) procedures. The experimental part of the study involves conducting fire tests on both full-scale steel structures and reduced-size samples, taking into account the selected design fire scenario. The calculation part includes the construction of a mathematical model, a skin-element model, the modeling process (thermal and static analysis), and the fulfillment of the conditions for ensuring the fire resistance of the structure. A computer model was developed to analyze the thermal state of a fire-protected steel beam.Verification of the results showed a sufficient level of modeling accuracy: the maximum deviation of the calculated temperatures from the experimental data was recorded atthe 40th minute of exposure to the standard fire temperature regime and was 13 °C, which corresponds to a relative error not exceeding 3.1%.Key words:fire resistance, reactive fireproof coating, critical temperature, steel structures.