Features of Calculating the Fire Resistance Limit of Beams From Construction Steels

One of the main directions of research in the field of increasing the actual limits of fire resistance of steel structures is the development and implementation of fire-resistant rolled products with increased thermal stability. Fire-resistant steels are steels whose yield strength when heated to 600 °C is at least 60 % of the yield strength at 20 °C. For their wide application in construction, information is needed on the change in the strength properties of fire-resistant rolled metal products at high heating temperatures. In addition, it is required to develop a method for assessing the bearing capacity of steel structures considering the nature of the temperature distribution in their cross section. The introduction of fire-resistant steels and the proposed method of calculation will in some cases will allow to ensure the normative limit of fire resistance of load-bearing structures or reduce the cost of their fire protection. The experimental and calculated data are obtained concerning the limits of fire resistance of beams made of steel rolled metal of classes S355, S390, as well as S355P and S390P with increased heat resistance. The use of the method for calculating the fire resistance limit of bent steel structures heated from three sides considering uneven heating in the cross section, demonstrates satisfactory convergence with the experimental data for beams made of building steels, including fire-resistant ones with increased thermal stability. Various levels of static load were modeled under the influence of the temperature regime of a standard fire. The research results contribute to the introduction of new types of fire-resistant building steels for the construction of buildings from metal structures. This will increase their safety and stability in case of fire and will lead to a reduction in the construction costs.