This document specifies a test and assessment method for determining the contribution made by fire protection systems to the fire resistance of structural steel beams, I and H sections, in the horizontal plane containing openings in the web which may affect the structural performance of the beam. It is applicable to beams subjected to three or four sided fire exposure.
For any cellular beam with a single web opening or where the web openings are considered to be of small diameter in relation to the web depth the applicability of this document is intended to be determined by a structural engineer
This document adopts the principle of establishing ratios of temperatures between and around openings in the web of a beam with the temperatures of a solid portion of that beam. This is with the intention that these data can be utilised within a structural model to derive the value and location of the associated limiting temperature of the beam at the fire limit state. The limiting temperature is then used in conjunction with data for the fire protection material determined from ISO 834-10 and ISO 834-11 to determine the necessary thickness of fire protection material for beams with web openings.
This document applies to fire protection materials that have already been tested and assessed in accordance with ISO 834-10 and ISO 834-11 and is not intended to be used in isolation. It covers fire protection systems that include both passive and reactive materials which follow the section profile as defined in this document.
This document includes the use of a multi-temperature analysis (MTA) derived from ISO 834-11 as the basis for determining the thickness of fire protection for beams with web openings.
This document contains an assessment method, which prescribes how the analysis of the test data should be made and gives guidance on the procedures that could be undertaken.
The assessment procedure can be used to establish:
a) The thermal response of the fire protection system on cellular beams, (the thermal performance) on the basis of the temperature data derived from testing unloaded steel sections.
b) The temperature ratio between the web post and the web reference temperature, which will vary depending on the web post width.
c) The temperature ratio between points around the web openings and the web reference area.
d) A structural model that can be used to derive limiting temperatures for cellular beams.