(The following is a draft, developed in consultation with Jeff King, for his power-point presentation on the collapse of the towers. King finished a complete presentation and had it ready for the Sept. 11 program, but could not show it due to a technical failure. Since this is only our draft of King's superior later presentation, we are presenting it here for the record only, and urge readers interested in alternative views of how the towers collapsed - none of which have entirely convinced us but all of which are intriguing - to instead check out Jim Hoffman's treatment at wtc7.net - NL/BKS)
Of all of the terrifying images on September 11, the collapsing Twin Towers were among the most horrific. A shocked nation saw the two largest structures in the New York City skyline dramatically crumble its eyes. Given the unprecedented dimensions of unfolding horror on their television screens that day, most Americans (most understandably) automatically connected the collapse to the crashing of Flights 11 and 175 moments before.
But since, serious question have been raised about the official explanations of the collapses. Many of these questions remain unanswered to this day. Citizen Eric Hufschmid and research scientist Jim Hoffman, who each have done painstaking analyses of the collapse of the Towers, have found what they consider to be excellent reasons for doubting the explanations forwarded for them.
Could Fire Damage Have Brought Down the Towers?
A collapse theory advanced by the program NOVA held that the heat of the fires, fueled by huge amounts of jet fuel, burned hot enough to melt the buildings’ steel columns and foment a weight-driven collapse.
But: to melt steel, a fire must burn at a temperature near 2,770 degrees Fahrenheit (1,500 C). The Towers fires were hydrocarbon fires, which do not burn at temperatures nearing the melting point of steel. MIT Professor Thomas Eagar is on record as stating that the fires probably burned at a temperature of 1,200-1,300 degrees F, and 1,600-1,700 degrees F at most.
Eagar, however, believes that the buildings did collapse due to fire. He argues that if the fires reached a temperature of 1,300 degrees, the steel, while not melting, would have lost 80% of its strength, which could have engendered the collapse.
But consider that there is an important distinction between temperature and heat. The fires could well have burned at 1,300 degrees, but that does not mean that they automatically would have heated the steel columns to a temperature of 1,300 degrees, which is what would be needed for the collapse Eagar envisions. Thus, the 1,300 degree fire would have had to have been directly applied to the steel for enough time to raise its temperature to 1,300 degrees. And it would have had to have been a big fire to heat enough steel to collapse the building.
But as Eric Hufschmid shows in his video Painful Deceptions and book, Painful Questions, (p. 35) the fires do not appear to have been the kind which could heat the core steel to the point needed for a collapse. Before the second building had been hit, the first building had thick, black smoke pouring from the impact zone, an indication that the fire burning within it was wanting for oxygen. Fires further inside the building, which would have had to burn intensely to weaken core steel columns, would have likely been even more oxygen-starved, since they had even less exposure to atmospheric oxygen than the fires on the outside of the building.
It is unlikely that there were enough widespread fires burning long enough and at sufficient temperatures to heat enough core steel to the point that it would permit the total collapse of the Towers.
But perhaps the fire caused the collapse by different means. This is the claim made by proponents of a version of the "pancake theory" theory of collapse. According to Professor Eagar, it would have been sufficient for a hot fire to weaken just one floor. On this view the ‘angle clips’, which ‘held the floor joists between the columns on the perimeter wall and core structure’, would have failed after being severely burned. Once they failed, it would have placed an extra load on the remaining angle clips in the area, producing an "unzipping effect" which ultimately would lead to the collapse of that floor. Immediately afterward, the floors above it would have failed, creating a "domino effect" of pancaking floors one on top of the other. The FEMA report lends its support to the possibility of a "pancake-type of collapse of many floors."
But there are a number of serious problems with this theory, the gravest of which perhaps is the fashion in which the buildings in fact collapsed. The Towers fell at almost free-fall speed. Is there a legitimate explanation for the fact that the supposedly-pancaking floors met virtually no resistance on their way down from the virtually undamaged, unweakened steel on the lower floors?
Further, as research scientist Jim Hoffman has pointed out, both the NOVA program and Eagar’s theories omit the existence of cross-trusses, which Hoffman claims would thwart the zipper effect. (SHOW SLIDE 17). Also, the FEMA report (SHOW SLIDE 18, 19, 20 highlights).
Thus, according to Hoffman, a truss theory-type failure would have, at best, left the perimeter wall and core standing. The floors would have slid down the cores like records on a spindle. But images of the collapses clearly show that did not happen.
Hoffman concludes that "(i)f damage due to impacts and fires were sufficient to cause some kind of collapse, it would have caused the tops to topple like trees, leaving the structures below the impact zones standing." (SLIDE 22)
The unlikelihood of a fire-based collapse is strengthened by the fact that no steel structure high-rise has ever collapsed due to fire. Other skyscrapers have been ravaged by severe fires. Examples include: One Meridian Plaza in Philadelphia, in 1991. A fire blazed for 18 hours in it, gutting 8 floors.
Another fire hit the First Interstate Bank Building, and it burned for 3-1/2 hours, gutting four floors.
As Hoffman notes, both fires exhibited: large emergent flames, extensive window breakage, and fire lazes that filled multiple entire floors.
These fires were much worse than those in the Twin Towers or Building 7, yet neither fire significantly damaged vertical steel columns.
The fact remains that outside of controlled demolitions, total collapses of steel buildings are extremely rare, even in the event of severe earthquakes.
2. Could the airplane impact have contributed to the collapses?
According to Professor Griffin, forensic tests performed on some of the recovered steel showed that it met or exceeded standard requirements. Also, the FEMA report noted that the floor framing system was complex and far more redundant than typical bar joists systems. The buildings themselves swayed a bit on impact, but were not thought to have been compromised by the fire company during the rescue effort. And as Eric Hufschmid noted, a minute or so after the North tower impact, the tower was "quiet, stable and motionless".
The editor of Fire Engineering, Bill Manning, went on record about the issue in January 2002, stating, "the structural damage from the planes and the explosive ignition of jet fuel in themselves were not enough to bring down the towers." Manning went on in the same article to launch a searing attack on the agencies in charge of the investigation for removing the evidence of the collapse before it could be thoroughly examined. (Manning quote "a half-baked farce)
He thought it was an explosion, and he was right there.
The Federal Emergency Management Agency was a picture of woeful inadequacy.
FEMA assembled a group of volunteer investigators: the Building Performance Assessment Team (BPAT), and gave them a budget of only $600,000.
The BPAT investigators were not allowed access to Ground Zero. They were only allowed to examine the few large pieces of steel that made it to Fresh Kills Landfill. They had to guess where the pieces had come from
Their analysis was only from October 7-12.
By the time BPAT published their report: The World Trade Center Building Performance Study, Ground Zero had been scrubbed.
The report attempted only to explain the collapse of the North Tower. Neither the South Tower nor Building 7's collapse was explained.
Returning to Manning’s criticism of the investigation, recall that the city accepted a plan by Controlled Demolition Inc. for the recycling of the steel, the same company which handled the demolition of the Federal building after the Oklahoma City bombing, 11 days after the attack.
The steel from the collapse was sold to scrap metal vendors for a low price. The vast majority of it was quickly removed to ships destined for blast furnaces in India and China. Investigators were barred from Ground Zero, except for one "guided tour". People were threatened with arrest for taking photographs. The evidence destruction operation was conducted over the concerted objections of victims' family members and the firefighting community.
3. What could have happened, then?
Firemen video
Maybe this is just understandably loose talk from a few men who have just narrowly escaped serious injury or death. But researchers Hufschmid and Hoffman agree that the buildings have a number of characteristics consistent with controlled demolitions. Hoffman, for instance, points out that:
Dust and fragments were ejected from the towers at high velocities.
The tops of the towers exploded into descending mushrooming clouds of dust.
The mushrooming dust clouds remained centered as they devoured the towers.
The dust clouds grew to volumes several times the buildings' volumes, and covered Lower Manhattan with dust.
The non-metallic components of the towers and their contents were pulverized to sub-100 micron dust.
The steel superstructures were shredded.
Intense heat in the basements melted the foundations of the core columns.
The pulverization of concrete into so fine a dust is hard to explain without resort to explosive devices in the towers.
Notice, too, the presence of jets of smoke emitting from the building during the collapse, but much below the point of impact of the collapsing section. These ‘squibs’ are also consistent in what one would expect from a well-timed, controlled demolition, because they would be evidence of the purposeful destruction of supporting steel below the impact zone. Destroying the internal steel could result in the telescoping effect seen in the Towers’ collapse.