Sunday, 4 September 2011

9/11 Conspiracies and Common Sense.

I like to think I have an open mind and evaluate all the available data before coming (usually) to a correct conclusion. I used to earn a nice wedge of money using those skills until 9/11 happened, a little too close for comfort (we lost a guy in the twin towers where I worked and only two weeks before had a couple of my engineers in New York. Its also possible that a few weeks later I myself would have been visiting the WTC), which made me do a complete about turn and chose family before career.

So I have an especial interest in the theories surrounding 9//11.

Of all the conspiracies, there is one that to me has relevance even today. That is, how could the WTC buildings collapse in the way they did on the day? I say that because all the buildings, including WTC7 fell in an apparently controlled manner. That is, they fell straight down, all the floors collapsing down perfectly on each other.

Now, structural engineers and demolition experts will say that this is an extremely difficult thing to do. Masses of preparation has to be made in order to weaken a building so it collapses on itself. If the preparation isn't done, the building can half collapse, or the top half may shear off and fall off the side; there are innumerable scenarios that could happen if the building isn't demolished correctly.

First off, lets look at the twin towers: yes they were hit by airliners which imparted huge kinetic energy into the structure. The jet fuel also created massive fires which could have weakened the structure. But the fact is that I would expect once the collapse had started, for the floors below the collapse to offer some resistance to the falling floors above and therefore see some sideways movement of the debris as the upper floors slide off the top of the lower floors.

On the day it was clear there was no sideways movement at all: the floors simply pancaked one on top of the other.

The same goes for WTC7, which also fell straight down, after failing structurally we are told, by fires burning in the building. Again, the similarities with a controlled demolition are amazing, the building falling within its own footprint. No lateral movement and therefore no resistance to the falling concrete is evident. Of course 9/11 was an exceptional day, but the laws of physics don't usually take a day off. Either the building design was flawed (and by inference so is every other similar building) or there was something exceptional going on that we have yet to be told about.

So, keeping an open mind, at the very least there appears to be issues regarding the safety of high-rise buildings when subjected to quite ordinary fires, as in the case of WTC7. The only extrordinary thing on the day was the fires in WTC7 were allowed to burn uncontrolled for hours. But the thing is, if there's a risk of building collapse due to fire damage, would you risk putting firefighters into that building to control the fire? If the building is structurally sound at one second and then an apparent blancmange the next, how long do you risk lives to control a building fire and what point do you pull firefighters out?

There are lots of questions that have not satisfactorily been answer even after a decade:

1. How can buildings made of reinforced concrete collapse in such a way from fire damage alone (as in the case of WTC7)?

2. What research have building regulators done to mimic this behaviour in high-rise buildings and develop measures to prevent it recurring?

3. What extra provisions have building regulators put in place since 9/11 to protect existing high-rise buildings from fire-initiated collapse given the obvious weakness?

4. What new building regulations have regulators put in place since 9/11 to prevent a recurrence of the fire-initiated collapse in new-build high-rise buildings?

5. Why isn't the apparent risk of high-rise building collapse better and more widely understood in the general population, if it's the certainty that the official 9/11 line takes?

6. How many people's lives are at risk every day from similar collapses?

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