Test methods for determining the contribution to the fire resistance of structural members - Part 6: Applied protection to concrete filled hollow steel columns
This European Standard specifies a test method for determining the contribution of fire protection systems to the fire resistance of structural concrete filled hollow steel columns. The concrete can be lightweight@ normalweight or heavyweight concrete@ and of all the strength classes provided for in EN 1994-1-2. The use of a dry sand is considered to be an alternative@ conservative approach to the use of wet concrete. A specification for dry sand is given in 5.6.3. The method is applicable to all fire protection systems used for the protection of concrete filled hollow columns and includes sprayed fire protection@ reactive coatings@ cladding protection systems and multi-layer or composite fire protection materials. If there is no hollow section data from prEN 13381-4 (revision of ENV 13381-4:2002) or prEN 13381-8 (revision of EN 13381-8:2010)@ this European Standard cannot be used. For passive systems@ this data can be derived using the Formula in Annex A of prEN 13381-4 (revision of ENV 13381-4:2002). Testing to this European Standard is not required if the fire protection thicknesses for hollow sections derived from prEN 13381-4 (revision of ENV 13381-4:2002) or prEN 13381-8 (revision of EN 13381-8:2010) are to be used for concrete filled hollow sections. The evaluation is designed to cover a range of thicknesses of the applied fire protection material@ a range of steel sections@ characterized by their diameters and wall thicknesses@ a range of design temperatures and a range of valid fire protection classification periods. The test method is applicable to fire protection systems which are intimately in contact with the structural column@ or which include an airspace between the structural column and the protection system. This European Standard specifies the fire tests which are carried out to determine the ability of the fire protection system to provide fire protection to composite columns. The tests produce data on the average steel temperatures of the composite column@ when exposed to the time/temperature curve according to the procedures defined herein. This European Standard also provides the assessment procedure@ which prescribes how the analysis of the test data should be made and gives guidance on the procedures by which interpolation is undertaken. In special circumstances@ where specified in national building regulations@ there can be a need to subject reactive protection material to a smouldering curve. The test for this and the special circumstances for its use are detailed in prEN 13381-8 (revision of EN 13381-8:2010). This exposure@ applicable to reactive fire protection materials@ is used only in special circumstances (which are specified in the national building regulations of a member state of the European Union) and is therefore not intended to be mandatory for all fire protection materials applied to concrete filled hollow steel columns. This European Standard ignores any contribution from the concrete to the structural capability of the hollow column and therefore only deals with thermal performance. The justification for using this approach is given in Annex B. The fire test methodology makes provision for the collection and presentation of data which can be used as direct input to the calculation of fire resistance of concrete/steel composite members in accordance with the procedures given in EN 1994-1-2. 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/concrete composite columns@ steel types and thicknesses@ concrete densities@ strengths@ thicknesses and production techniques over the range of thicknesses of the applied fire protection system tested. This European Standard details the fire test procedures@ which should be carried out to provide data on the thermal characteristics of the fire protection system@ when exposed to the European Standard temperature/time curve specified in EN 1363-1. The assessment procedure is used to establish: a) on the basis of temperature data derived from testing concrete filled unloaded tall columns and reference columns@ a correction factor and any practical constraints on the use of the fire protection system under fire test conditions@ (the physical performance); b) on the basis of the temperature data derived from testing short hollow steel sections filled with concrete@ the thermal properties of the 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 sections and grades and to the fire protection system.