New research published by the BRE has found not only that reinforced concrete is over-designed under current British Standards, but also that the development of the structural Eurocodes will enable designers to adopt a more performance-based approach.
The research report, The Fire Safety of Concrete Structures: Background to BS 8110 Fire Design, shows that the historical tests that provide the basis for design of reinforced concrete hold up well when analysed under modern conditions, and in many cases exceed requirements.
Research examined the performance of concrete elements under tabulated design figures taken from historical test data. In particular, it found that load ratio does not appear to have a significant impact, and that existing provisions for the fire resistance of reinforced concrete beams are extremely conservative.
The prescriptive design approach of BS 8110 has worked well because of its inherent simplicity.This is demonstrated by the performance of real buildings in real fires.However, in recent years fire engineering design has moved towards a performance-based approach, for which the structural Eurocodes will enable a more economic design process.