FIRE TESTS on vulnerable connections between cellular steel beams and columns are to be carried out by a Steel Construction Institute (SCI)-led joint venture, NCE learned this week.
The work is thought to stem from lessons learnt after collapse of the World Trade Center towers. Here, relatively flimsy connections between the perimeter columns and lightweight tubular steel floor trusses are thought to have failed first in the fires that followed the aircraft impacts.
However, traditional fire testing has usually focused on the performance of individual structural elements. Now Fabsec, developer of the precoated cellular Firebeam launched earlier this year (NCE 16 May), is to extend its SCI-backed tests to cover connections.
'We'll be investigating the need to apply intumescent coatings to bolt heads and in the gap between the column and the end of the beam after erection, ' explained Fabsec managing director Philip Toczek. 'So far research has concentrated on the resistance of the 'web posts', the narrow areas between the openings in the web.'
Firebeams are precoated with intumescent paint at two licensed fabricators before delivery to site. A series of fire tests on Firebeams under load, carried out at the Warrington Fire Research Centre under the supervision of the SCI, proved that Fabsec's FBEAM 2 software could accurately optimise the thickness of intumescent coatings for any desired level of fire resistance up to 120 minutes.
New design guides to cover web slenderness and cell spacing derived from the tests are due to be published by SCI in the near future.
INFOPLUS www. fabsec. com