Fires and Building Collapses

WTC Building 7

Fires And Steel Building Collapses

The official explanation that fires caused the collapse of Building 7 is incredible in light of the fact that fires have never caused a steel-framed building to totally collapse, before or after September 11th, 2001.

Steel-framed highrises (buildings of fifteen stories or more) have been widespread for over 100 years. There have been hundreds of incidents involving severe fires in such buildings, and none have led to complete collapse, or even partial collapse of support columns.
The Interstate Bank Building fire consumed several floors but did not damage the steel superstructure.

The Interstate Bank Building fire consumed several floors but did not damage the steel superstructure.

Recent examples of highrise fires include the 1991 One Meridian Plaza fire in Philadelphia, which raged for 18 hours and gutted 8 floors of the 38 floor building; 1 and the 1988 First Interstate Bank Building fire in Los Angeles, which burned out of control for 3 1/2 hours and gutted 4 floors of the 64 floor tower. Both of these fires were far more severe than any fires seen in Building 7, but those buildings did not collapse. The Los Angeles fire was described as producing "no damage to the main structural members". 2

Research indicates that even if a steel frame building were subjected to an impossible superfire, hundreds of degrees hotter and far more extensive then any fire ever observed in a real building, it would still not collapse. Appendix A of The World Trade Center Building Performance Study contains the following:

In the mid-1990s British Steel and the Building Research Establishment performed a series of six experiments at Cardington to investigate the behavior of steel frame buildings. These experiments were conducted in a simulated, eight-story building. Secondary steel beams were not protected. Despite the temperature of the steel beams reaching 800-900 C (1,500-1,700 F) in three of the tests (well above the traditionally assumed critical temperature of 600 C (1,100 F), no collapse was observed in any of the six experiments).

In building fires outside of such laboratory experiments, steel beams and columns probably never exceed 500 C. In extensive fire tests of steel frame carparks conducted by Corus Construction in several countries, measured temperatures of the steel columns and beams, including in uninsulated structures, never exceeded 360 C. 3
References

1. One Meridien Plaza, SGH.com, [cached]
2. Interstate Bank Building Fire Los Angeles, California (May 4, 1988),
3. Fire Resistance of Steel Framed Car Parks, corusconstruction.com, [cached]