Contribution of fire protection to the fire resistance of structural (steel) members

Fire-resistance of specific building elements is categorised into two types of elements, separating elements is intended for use in maintaining separation between two adjacent areas or compartment or fire zone of a building in the event of a fire, and non-separating elements are structural elements, i.e. beams, columns, that is essential to have the ability to withstand & maintains its strength or loadbearing capacity during exposure to fire in a given time and temperature.


Fire protection systems protect steel members such that the temperature of the steel member is limited throughout the period of exposure to fire. Steel elements lose their load-bearing capacity at approximately 550 °C during a fire. Applying steel fire protection material provides a sustaining (structural) solution to maintain building steel structures' stability.



EN 13381-4 and EN 13381-8 are European Standards that specify a test method for determining the contribution made by applied fire protection systems to the fire resistance of structural steel members (e.g., beams or columns – except those sections with an opening in the web) and evaluate their ability to remain coherent and attached to the steelwork when exposed to the standard temperature/time curve specified in EN 1363-1. Applied passive fire protection is tested according to EN 13381-4, and applied reactive fire protection is tested according to EN 13381-8, respectively.


Passive fire protection systems applied in structural steelworks are materials that do not change their physical form when exposed to heat or fire. These materials for structural protection come in various forms and applications, such as sprayed coating with or without mesh reinforcement, rendering, mat board or slab product, etc. These applications protect through their physical or thermal properties. Annex B of EN 13381-4 provides the method to measure the properties of fire protection materials to determine the thickness, density, and moisture content of the passive fire protection materials used in fire resistance tests to accurately predict the required fire protection thicknesses from the test result.


Reactive fire protection systems are materials that expand or intumesce when exposed or subject to heat or fire. They are specifically formulated to provide a chemical reaction upon heating such that their physical form and, in so doing, provide fire protection by thermal insulation (shielding or providing a barrier from the heat) and cooling effects. Reactive fire protection is typically comprised of an intumescent coating applied on the specific primer of a structural element and with or without compatible top coating. Annex B of EN 13381-8 provides the method to measure the properties of fire protection materials to determine the thickness of reactive fire protection materials (primer, intumescent, topcoat) used in fire resistance tests to accurately predict the required fire protection thicknesses from the test result.


One of the critical examinations performed in the EN 13381-4 and EN 13381-8 testing of a structural steel fire protection system is stickability (bond strength). This is to determine the ability of a fire protection system to remain sufficiently coherent and in position for a well-defined range of deformations, furnace, and steel temperatures, such that its ability to provide fire protection is not significantly impaired.


Compared to other testing methods of fire-resistance testing of building elements, these European Standards provide an “Assessment” procedure which, through the standards’ defined approach, analyses the temperature data obtained from the tested loaded and unloaded steel sections, which form a basis relating the time to reach a specified steel temperature. In this process, predicted performances of a range of steel sections, section factor, and the thickness of the applied fire protection material, including the field of design temperatures, are assessed to classify specific fire durations. It is recommended that the same testing laboratory should perform this procedure to deliver complete testing data records analysis to produce a reliable assessment report.