Feature of fire resistance calculation of steel structures with intumescent coating

Abstract

The problem of estimation of fire resistance of steel frame structures with intumescent coatings is considered. It implies that both physical properties of a covering (its thickness and structure) and mechanical properties of a metal structure change critically at heating. All above changes should be considered to maintain the standard values of fire resistance of a construction at calculation. Usually, known technical characteristics of fire resistance of intumescent coverings are used for estimation of fire resistance of steel structures with intumescent coverings. Importance of taking into account the influence of strength loss time at heating of a steel structure on calculation of fire resistance limit of system “intumescent fireproof coating steel structure” is shown in the article. On an example of calculation of heating time to the critical temperature of steel columns and beams protected by intumescent coating, it is shown that own heating time of steel structures before they lose strength makes 10 to 16 % from a settlement limit of fire resistance. This fact should be considered at the forecast of fire resistance of steel frame structures with intumescent coatings.

Thermal effect of a fire on a steel beam with corrugated wall with fireproof mineral-wool cladding

“…However, the recommendations lack data on the methods of estimation evaluation of steel beams with corrugated walls and the correctness of the use of conventional approaches. This can also be traced by the results reported in work [6].…”

“…Along with the experimental method of fire tests, the use of estimation methods has become common in order to assess the fire resistance of steel beams [5]. The main recommendations for the application of this approach are contained in the regulatory documents of the United Europe, for example in [6]. The advantages of those methods include sufficient flexibility, the ability to take into consideration the entire variety of steel grades, from which the studied beams are made, various geometric sizes of structures, and various types of fireproof materials.…”

“…At the same time, in work [12], which reports a study into such beams with fire protection cladding for fire resistance, the practical aspect of the estimation fire resistance assessment is insufficiently disclosed, taking into consideration the determining of belonging to the designated fire resistance class. Effective practical approaches are used in work [16] but they have no reference to normalized methods for calculating steel structures for fire resistance [6]. In addition, those works do not cover the results of studying the fire of steel beams with a corrugated wall using fire protection and without it with a follow-up comparison of results.…”

“…Based on a normalized approach, work [6] recommended a procedure to tackle the mechanical problem of design when assessing fire resistance under the influence of the standard temperature of fire on a beam with a flat wall. However, in the case of beams with a corrugated wall, this procedure can produce unpredictable results.…”

“…However, in the case of beams with a corrugated wall, this procedure can produce unpredictable results. The mathematical model for solving the mechanical problem given in paper [6], based on standards recommendations, considers changes in the mechanical properties of steel when the temperature changes. At the same time, the state of failure of the beam is predicted by comparing the change in its resistance under the influence of temperature and active load.…”