An analysis of the global structural behaviour of the Cardington steel-framed building during the two BRE fire tests

This paper presents the results of an analysis of the global structural behaviour of the 8-storey steel framed building at Cardington during the two BRE large-scale fire tests. These two tests (the Corner test and the Large compartment test), together with the four fire tests conducted by British Steel, formed the core programme of a multi-million pound research project sponsored by the UKʹs Department of Environment and the European Coal and Steel Community. These tests were carried out to investigate the performance of whole building structures under realistic fire conditions and to provide quality experimental information for the validation of various numerical models. The results of these two BRE tests were analysed using a specialist finite element computer program (to be referred to as FIREFRAME in this paper) and this paper presents the main findings of this study. Due to the difference in their fire intensities, the two BRE tests resulted in markedly different structural behaviour of the steel frame. This gives rise to an opportunity to check the capability of the computer program. The results of this analysis seem to indicate that FIREFRAME is capable of simulating flexural bending behaviour. However, in order for the program to simulate the Cardington frame behaviour during the Corner test, it requires a more advanced numerical procedure to deal with slab tensile membrane behaviour at large deflections. Test and computer simulation results suggest that columns may attain large moments as a result of being pushed by the adjacent hot beams, but as the test column temperatures were low, it was not possible to assess the column failure behaviour. Furthermore, computer simulations indicate that large sagging moments may develop in heated beams during cooling, but further research is required to check whether this would lead to beams failure.