Hole in the Wall
An Engineer Checks In: Controlled Demolition Was Not a Part of the Picture
RECEIVED Mon., Aug. 28, 2006
Dear Editor,
The idea that the WTC buildings are the first steel-framed buildings in the history of civilization to completely free-fall collapse is ridiculous to Colin Donoghue ["Postmarks," Aug. 18]. As an experienced engineer, I disagree with him that I or anyone else should think so, too.
The collapse of these buildings (including WTC 7) was from a loss of strength in the steel due to heating from burning building contents. In the twin towers, the collapse was accelerated by a loss of lateral stability in the outer shell columns by collapse of the floor trusses in the area of the strikes.
It was not necessary to reach the melting point of the steel because steel loses about half of its strength at 1,000 degrees Fahrenheit, well within the range of temperatures in the fire areas. The steel in the towers failed because the fireproofing was lost in the impacts. In WTC 7, the fires burned all day without being fought, more than any fireproofing system could protect from.
The idea that controlled demolition was involved is ridiculous. Preparing for a demolition involves much more than just setting a few charges and pushing a plunger. Preparing a steel structure for demolition involves extensive weakening of the structure by ripping away the interior finishes and notching the beams and columns with torches before setting any charges. There is no way to hide this or to do it at night. The puffs of smoke seen in the films are air being forced out between the floors as the buildings pancaked. Moreover, if there had been an explosion due to demolition in the towers, then unmistakable evidence would be found in the form of cut structural steel. None has ever been located.
Why did the buildings pancake straight downward? It is simple. The upper sections of the towers were unimaginably heavy and, when the support of the columns in the damaged areas was lost, they fell downward because that is the direction that gravity pulled them, and there was nothing in the way that was capable of stopping them.
Don't you think that it is a little suspicious that there has never been a single, licensed professional structural engineer who has put forward an alternative collapse scenario that explains the evidence? I agree that all of us should be skeptical of what we are told – especially today – but the structural engineering community is in agreement on what happened on 9/11, and controlled demolition was not a part of the picture.
The idea that the WTC buildings are the first steel-framed buildings in the history of civilization to completely free-fall collapse is ridiculous to Colin Donoghue ["Postmarks," Aug. 18]. As an experienced engineer, I disagree with him that I or anyone else should think so, too.
The collapse of these buildings (including WTC 7) was from a loss of strength in the steel due to heating from burning building contents. In the twin towers, the collapse was accelerated by a loss of lateral stability in the outer shell columns by collapse of the floor trusses in the area of the strikes.
It was not necessary to reach the melting point of the steel because steel loses about half of its strength at 1,000 degrees Fahrenheit, well within the range of temperatures in the fire areas. The steel in the towers failed because the fireproofing was lost in the impacts. In WTC 7, the fires burned all day without being fought, more than any fireproofing system could protect from.
The idea that controlled demolition was involved is ridiculous. Preparing for a demolition involves much more than just setting a few charges and pushing a plunger. Preparing a steel structure for demolition involves extensive weakening of the structure by ripping away the interior finishes and notching the beams and columns with torches before setting any charges. There is no way to hide this or to do it at night. The puffs of smoke seen in the films are air being forced out between the floors as the buildings pancaked. Moreover, if there had been an explosion due to demolition in the towers, then unmistakable evidence would be found in the form of cut structural steel. None has ever been located.
Why did the buildings pancake straight downward? It is simple. The upper sections of the towers were unimaginably heavy and, when the support of the columns in the damaged areas was lost, they fell downward because that is the direction that gravity pulled them, and there was nothing in the way that was capable of stopping them.
Don't you think that it is a little suspicious that there has never been a single, licensed professional structural engineer who has put forward an alternative collapse scenario that explains the evidence? I agree that all of us should be skeptical of what we are told – especially today – but the structural engineering community is in agreement on what happened on 9/11, and controlled demolition was not a part of the picture.
Ethan A. Love