9/11 'conspiracy' theories challenged by Cambridge research

A new mathematical analysis of the collapse of the World Trade Centre has been published by a Cambridge University academic, with results that challenge conspiracy theories surrounding the September 11th attacks.

The new paper, by Dr Keith Seffen, uses established engineering models to demonstrate that once the collapse of the twin towers began, it was destined to be rapid and total.

Although the causes that initiated the collapse of the twin towers are now well understood, engineers continue to speculate about the speed and totality with which the buildings were demolished during the fateful attacks.

Some have even dared to suggest that the catastrophic events that followed two planes being flown into the buildings were the result of a conspiracy that extended to the top of government itself.

Dr Seffen, a Senior Lecturer in the Structures Group in the Department of Engineering, was moved to find a scientific explanation for the collapse when he heard about reports of possible insider involvement. Claims of "controlled demolition" were being suggested, in order to explain the speed, uniformity and similarity between the collapses of both towers.

"I thought immediately that there had to be a rational explanation for why collapse happened as it did, one which draws on engineering principles," he said. "After searching the current literature, it became clear that many studies focused on the phase just before collapse settles in.

"They rightly show that the combination of fire and impact damage severely impaired those parts of the building close to where the aircraft hit to hold the weight of the building above. The top parts were bound to fall down, but it was not clear why the undamaged building should have offered little resistance to these falling parts."

Dr Seffen's new analysis, which will be published in a forthcoming issue of the American Society of Civil Engineers' Journal of Engineering Mechanics, focuses on calculating the residual capacity of the building to resist the weight of the floors above under collapse conditions.

He then develops a dynamic model of the collapse sequence, which simulates the successive squashing, or "pan-caking" of individual storeys based on the residual capacity already identified. The process is already well known from other studies of progressive collapse, but usually applies to other structures such as undersea pipelines, rather than buildings.

This allowed Dr Seffen to predict that the residual capacity of both buildings was limited, and once collapse had started, it would take only 10 seconds for the building to go down - just a little longer than the free-falling of a coin dropped from the top of either tower.

"The aim was to produce a credible scientific explanation for the totality of collapse once it began," he said.

"In all senses, the collapse sequence was quite ordinary and natural. The World Trade Centre towers were designed to absorb an aircraft impact, but an accidental one with much less fuel and speed. It is widely acknowledged that the impacts on September 11th were extraordinary, which led to consequences well in excess of the design capacity for the buildings. The original design of both towers must be praised for standing as long as they did, saving more lives than might have been expected."

I'm reading Report from Ground Zero right now. This is what a couple of guys said regarding WTC7:

JOE DUNNE, First Deputy Police Commissioner (NYPD):
"I saw people walking around on the street, and they all had the look of shock on their face. They were walking slowly, and many of them were walking into harm's way. They were walking south on Church Street. Many of these people were coming out of (WTC) 7, 5, and other surrounding buildings that had suffered collateral damage. In fact, at this point in time, those buildings were now on fire."

HARRY MEYERS, Assistant Chief of Department (FDNY):
"We were all pretty much on board that tower 7 was going to fall. We just didn't know when or in which direction. Everybody forgets about 7, but that building was forty-seven stories, and that in itself would have been a very major event. We couldn't fight the fire in tower 7 because we didn't have enough water. All the water mains were down. What water we had was being supplied by the boats, through large-diameter hose. It would have been a chaotic situation, in any event, trying to get in there under those circumstances and fight that fire ..."

Battalion Chief John Norman, Special Operations Command (FDNY):
"I started to go down Vesey toward West, but there was a lot of debris blocking the way and they were telling me no, you don't want to go down there. They're worried about that building collapsing. I looked at 7 World Trade Center. There was smoke showing, but not a lot and I'm saying that isn't going to fall. So I went up Church Street two more blocks and went across to West and went right down behind 7 and got a good look at three sides.

Again, there were a lot of fires on the ground, some crushed mail trucks, some burned-up engines. It was a scene out of a war zone. I continued around to West and Vesey and reported into the command post. They were very concerned about fire extending into the telephone company building.

They gave me a couple of companies and said get into the telephone company building and check on extension there. We had extension on the first and second floors, so we took some standpipe lines, put them in operation and knocked that down. From there, we looked out at 7 World Trade Center again. You could see smoke, but no visible fire, and some damage to the south face. You couldn't really see from where we were on the west face of the building, but at the edge of the south face you could see that it was very heavily damaged.

But I never expected it to fall the way it did as quickly as it did, 7. But we took some defensive positions, actually tied the lines off and pulled the companies back from the building. I didn't feel too bad once we got back away from the perimeter just because that's a real, real heavy, old-style building. We knocked down any fire and checked for extension in the phone company building. We tied the lines off and left them flowing out into the street onto the debris piles that were burning out in the street there between the phone company and 7."

As for Building 7, I think the recent (within the last month?) show on
The History Channel gave at least a plausible visual animation of why
it collapsed.
IIRC, the interior included a large “open space” for a lobby on the
lower floors, thus the building was (as planned) held up by a less than
the standard number of columns.

Thus, with the collateral damage of 9-11, fire and lack of resources
to control the conflagration...Building 7 fell.

I’m not saying that’s the actual reason. But the show did make a
reasonbale argument for that scenario.

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