Substantiation of the simplified method of evaluation of fire resistance of protected steel structures.

Abstract

For the assessment of fire resistance of protected steel structures, European methods are used, which are given in standards EN 13381-4: 2013 and EN 13381-8: 2013. The practical implementation of these methods requires considerable material costs, in particular, the need for the use of special fire furnaces with equipment for loading steel structure specimens and the creation of a large number of standardized specimens. Therefore, it is important to develop a simplified method, and why this research is dedicated. The substantiation of the test procedures, the parameters of the test specimens (their number, shape, cross-section coefficient, thickness of the fire protection system) and the critical values of the critical temperature of steel for a simplified method of evaluating the fire resistance of protected steel structures are given in the article. It is shown that it is expedient to use steel columns with a height of 2.0 m of the I-section of profile No. 20 according to DSTU 8768, which have the highest value of the cross-section coefficient. The critical temperature range of steel is set from 350 ºС to 500 ºС, for which the simplified method should calculate the minimum thickness of the fire protection system. The choice of such a range is justified by the acceptable difference between the results of the fire resistance rating of the protected steel structures, obtained taking into account and without taking into account the performance of the fire retardant system and (or) its ability to remain intact during fire exposure. The values of the minimum thickness of the coating layer (plaster) made of flame retardant material "Endotherm 210104", which provide normalized classes of fire resistance of steel structures obtained by a simplified method. It is shown that for steel structures with a crosssectional ratio of significantly less than 294 м-1 are presented, the values of the minimum thickness of the fire protection system will be substantially smaller (by tens of percent) than those obtained by the simplified method.