prEN 13381-11

Test methods for determining the contribution to the fire resistance of structural members - Part 11: Applied protection to solid steel bars in tension based on mechanically loaded fire tests

Scope

This document describes the test and assessment procedure for determining the contribution of reactive fire protection systems to the fire resistance of solid steel bars used as tension members, when exposed to the standard temperature/time curve specified in EN 1363-1. In special circumstances, where specified in National Building Regulations, there can be a need to subject reactive fire protection systems to a slow heating curve (smouldering fire) as defined in EN 1363-2. The corresponding test and assessment procedure are described in Annex E. The fire protection performance is determined by testing mechanically loaded steel bars in horizontal orientation. Information regarding the testing of additional unloaded specimens is given to assess the influence of the bar orientation and smouldering fire behaviour.
The principles of the testing and assessment procedure can also be applied for other section shapes such as angles, channels and flats. This document does not include steel bars used as reinforcement in concrete construction.
The document is applicable to steel bars up to a maximum diameter of 130 mm. In the case of rectangular bars, the maximum edge length shall be limited to 130 mm with a maximum aspect ratio of 2:1 against the shorter edge length.
The test programme and the assessment are designed to cover:
- a range of valid fire protection classification periods;
- a range of thickness of the applied reactive fire protection system;
- a range of steel bar dimensions and profiles;
- a range of specified design temperatures;
- a range of load utilisation factors in case of fire;
- a range of bar orientation.
This document also provides the assessment procedure, which prescribes how the analysis of the test data shall be made and gives guidance on the procedures by which interpolation shall be undertaken. The assessment procedure is used to establish:
a) on the basis of data derived from mechanically loaded testing steel bar, any practical constraints on the use of the reactive fire protection system under fire test conditions (the physical performance);
b) on the basis of the temperature data derived from testing steel bar the thermal properties of the reactive fire protection system (the thermal performance).
The limits of applicability of the results of the assessment arising from the fire test are defined together with permitted direct application of the results to different steel types and sizes over the range of thicknesses of the applied reactive fire protection system tested.

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