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Remarkable New Steel Buildings with Integrated Fire Resistance

Prof.Eng. J.-B. Schleich

 

This contribution describes the present state of the art in fire engineering developments according to Annexes C, D and E of EN1991-1-2 (DAV 20.11.2002 ).

 

In the presently described buildings, instead of paying for protection materials in order to fulfil ISO fire requirements of 120 minutes and more, this money was used for the installation of active fire safety measures. Active fire safety produces real safety for people, f.i. by adequate partitioning, by safe escape routes, by proper smoke venting or by conveniently designed & maintained sprinkler systems. But at the same time active fire safety contributes in helping the structure resist realistic heating conditions as the potential severity of a fire and its probability of occurrence are cut down .

 

A first structure concerns an underground car-park built from 1999 to 2000, for which it was recognised that the safety conferred by the active fire-prevention methods may be considered when analysing the stability of the load-bearing structure and that a realistic type of fire, from cars burning, may be taken into account. Hence smoke detection and a high-density sprinkler system allowed to have the 16,8 m long steel beams fully visible without any thermal insulation.

 

Two six level office buildings, erected from 2000 to 2003, are described where the full set of active fire safety measures as presented in table E.2, Annex E of EN1991-1-2 was implemented. Hence smoke detectors were installed all over the buildings and automatic fire suppression is given through an automatic water extinguishing system of sprinkler heads also installed all over the buildings. Furthermore life safety is ensured by the numerously existing and extremely redundant safe escape ways. Consequently steel columns and the lower visible parts of the steel beams need not be covered by any insulation nor by any intumescent coatings.

 

Finally a 19 level office building, with a height of 75m, is presently being finalized (2003 to 2006) supported by a composite frame. The corresponding columns and beams are kept visible and present unprotected steel surfaces, which permits to fully exhibit the filigrane nature of steel. Of course again the full set of active fire safety measures as presented in EN1991-1-2 was implemented.

 

For all these buildings the natural design fire curve has been calculated using the Software OZONE developed under the leadership of the author by the University of Liège. The most critical fire scenario leads to air temperatures of approximately 500°C. The influence of these temperatures has been checked through the thermo-mechanical computer code CEFICOSS, which clearly indicates that, under those natural heating, no failure nor any critical deformation will occur. This is due to the fact that steel structures are in fact best protected by the active fire safety measures.

This contribution describes the present state of the art in fire engineering developments according to Annexes C, D and E of EN1991-1-2 (DAV 20.11.2002 ).

In the presently described buildings, instead of paying for protection materials in order to fulfil ISO fire requirements of 120 minutes and more, this money was used for the installation of active fire safety measures. Active fire safety produces real safety for people, f.i. by adequate partitioning, by safe escape routes, by proper smoke venting or by conveniently designed & maintained sprinkler systems. But at the same time active fire safety contributes in helping the structure resist realistic heating conditions as the potential severity of a fire and its probability of occurrence are cut down .

 

A first structure concerns an underground car-park built from 1999 to 2000, for which it was recognised that the safety conferred by the active fire-prevention methods may be considered when analysing the stability of the load-bearing structure and that a realistic type of fire, from cars burning, may be taken into account. Hence smoke detection and a high-density sprinkler system allowed to have the 16,8 m long steel beams fully visible without any thermal insulation.

 

Two six level office buildings, erected from 2000 to 2003, are described where the full set of active fire safety measures as presented in table E.2, Annex E of EN1991-1-2 was implemented. Hence smoke detectors were installed all over the buildings and automatic fire suppression is given through an automatic water extinguishing system of sprinkler heads also installed all over the buildings. Furthermore life safety is ensured by the numerously existing and extremely redundant safe escape ways. Consequently steel columns and the lower visible parts of the steel beams need not be covered by any insulation nor by any intumescent coatings.

 

Finally a 19 level office building, with a height of 75m, is presently being finalized (2003 to 2006) supported by a composite frame. The corresponding columns and beams are kept visible and present unprotected steel surfaces, which permits to fully exhibit the filigrane nature of steel. Of course again the full set of active fire safety measures as presented in EN1991-1-2 was implemented.

 

For all these buildings the natural design fire curve has been calculated using the Software OZONE developed under the leadership of the author by the University of Liège. The most critical fire scenario leads to air temperatures of approximately 500°C. The influence of these temperatures has been checked through the thermo-mechanical computer code CEFICOSS, which clearly indicates that, under those natural heating, no failure nor any critical deformation will occur. This is due to the fact that steel structures are in fact best protected by the active fire safety measures.