Loadbearing capacity criteria in fire resistance testing

Experimental testing may be used to demonstrate the fire resistance of building construction elements. In order to allow comparing the results of tests made in different laboratories on various types of elements, the tests have to be performed under well-defined standardised conditions. Such standards define the heating and loading conditions, but also the performance criteria that have to be applied to measure the fire resistance duration.
In Europe, the procedure that leads to the classification of building construction elements with regards to fire resistance involves a two level process. In the first stage, one or several tests are performed by a laboratory that must have accreditation according to ISO 17025, and one test report is issued for each test. Thereafter, a competent body will compile the necessary test reports and issue a classification report, the results of which can be used by the different stakeholders of the construction process, e.g. by authorities having jurisdiction.
For the loadbearing performance, it appears that different logical combinations of the criteria are considered in the test standard and in the classification standard, leading to a inextricable situation. This situation has to be fixed in order to lead to a complete credible and applicable system.
In order to provide scientific evidence about the consequences of adopting one or the other of both loadbearing definitions, the results of 46 tests performed in the fire resistance lab of the University of Liege in the recent years are analysed in this paper.