INFLUENCE OF FIRE PROTECTION SYSTEM PARAMETERS ON FIRE RESISTANCE OF STEEL STRUCTURES

Abstract

Existing fire protection systems for steel structures using fire-retardant profile coatings or fire-retardant screens are not always acceptable for practical use due to their considerable thickness required to ensure the highest fire resistance classes of these structures. Reducing this thickness can possibly be done by using a fire protection system that effectively combines the physicochemical properties of passive and reactive fire retardant materials, as well as fire shields. Uncertainty of influence of parameters of such system of fire protection on fire resistance of steel designs causes carrying out of research in this direction. The studies aimed to assess the fire resistance of steel structures with a fire protection system, which uses a fire shield and fire protection coating of the steel profile. Peculiarities of temperature dependences of steel structures of I-column profile with such combined system of fire protection on duration of fire influence on standard temperature mode are defined. It is established that the rate of temperature rise is the highest for a steel structure with a reactive fire-retardant coating of the profile (the value of 550 °C is reached for the duration of fire exposure 59 min), the lowest – for a structure with passive coating (this temperature is reached for 125 min). The influence of the parameters of the fire protection system on the fire resistance of steel structures is determined. It is shown that the use of fire shields leads to a significant increase in fire resistance of steel structures. If there is a reactive coating on the surface of the structure, this increase is from 90 % to 100 %. In the case of using a passive coating of the profile, the fire resistance of the structure increases by an amount ranging from 67 % to 88 %. The effectiveness of fire shields is greater in the presence of a passive coating on the surface of the structure than the reactive material. The use of reactive coating on the inner and outer surfaces of fire shields does not increase the fire resistance of the steel structure, which is protected by a screen.