OUT OF date practice and design procedures mean structures are commonly overdesigned fire engineers have warned.
Since the 11 September 2001 aircraft attacks on the World Trade Center in New York, there has been an acceleration of research into fire resistance, which is now yielding a better understanding of how structures respond and how building services are affected.
But common design practice uses prescribed fire limits, dictated by fire testing results of single unrestrained elements. This fails to reflect the performance of the structure as whole in a real fire, says a new report.
The new guidance document, Introduction to the fire safety engineering of structures, released last month gives a more intuitive perspective on fire design that fills the voids left by the existing UK codes and forthcoming Eurocodes.
'Although current fire tests offer a good benchmark for product comparisons, they fail to reflect a true fire event. It is only when you model a real fire in a real structure that you can improve the efficiency of design, ' said Institution of Structural Engineers fire task group chairman and report author Mick Green.
Instead of increasing fire protection in the light of the 11 September attacks, the report suggests that engineers are now able to cut protection by opting for more appropriate solutions.
'Design tools are now available to better consider the effect on the whole structure.
Looking at isolated sections can lead to misleading results, ' said Green.
Simply increasing fire protection will not necessarily improve performance, said Green. 'Often a more diverse approach which considers the structure's inherent fire resistance will provide the most appropriate solution.
'Such advancements could be dangerous without suitable guidance that is not available from design codes.'