CALCULATION OF THE HEATING RATE OF AN UNPROTECTED STEEL MEMBER IN A STANDARD FIRE RESISTANCE TEST

ENV.1991-2-7 is the new 'European standard code of practice for action s on structures exposed to fire'. The document recommends a standardiz ed procedure for the calculation of the fire resistance of a structura l member. For each member state of tile EU, a national application doc ument (NAD) is being drafted to provide values of those parameters use d in the calculations described in the code of practice. The first par r of this paper provides a justification of the values recommended for test piece surface and furnace emissivities as well as the safety fac tors in the UK version of the NAD. ENV.1991-2-7 is designed to have a working life of only three years, Lifter which its contents will be re viewed in the light of the experience gained during its use, before be ing issued as a final EN standard. The second part of this paper attem pts to identify the most important developments needed during this thr ee year period. There is an urgent need to develop a reliable means of measuring and controlling the total heat flux incident on a specimen during a standard fire resistance test. The availability of total heat flux control would allow modification of EN.1363-1 (the standard fire resistance test) to achieve harmonization of fire test results across the whole EU. A method has been developed by which existing fire resi stance test data can be used to calculate the total heat flux incident on the specimen at any instant during the test. The method has been u sed to compare the total incident heat flux/time characteristics of be am testing furnaces at the Warrington Five Research Centre (WFRC) and TNO (Delft) as well as the column furnace at the Borehamwood laborator y of the Loss compared with those implied in the draft UK-NAD for ENV. 1991-2-7. The latter has been shown to use heat flux/time characterist ics very similar to those derived from standard test data. Copyright ( C) 1996 Elsevier Science Ltd.