Quote:
Originally Posted by Ohio
Let me try to address this. The supporting pillars on each floor are designed to withstand all live (people, furniture) and dead (structure) loads on all the floors above it. Hence, going from top to bottom, the supporting structure grows in size as the loads increase. Practically, these incremental increases in load bearing capacity, may change 5 or 10 floors at a time, depending on the structural engineers.
These loads are basically static in nature, discounting a couple tons of weight from occupants coming and going. The only dynamic loads designed for would be movement from the earth and weather. Probably the worst of these in NYC would be hurricane force wind gusts, which would load one side of the base of the building and unload the other. Hence all skyscrapers must accommodate worst case wind gusts, and they can be significant on such a huge structure.
The tragedy of 9/11 presented entirely new dynamic loading. Once the structures at the crash site (perhaps a half dozen floors) buckled due to the intense heat, effectively dropping the available yield strength of the steel, dynamic loads due to gravity were introduced onto otherwise undamaged pillars beneath them.
The simple rule in dynamic loading says that the added forces of a moving load, at minimum, doubles the load. Thus a load which falls from only 1 mm, and never has opportunity to accelerate, STILL doubles the load. On top of this doubling, we must add the dynamic component of the weight falling roughly 10 feet at a time.
Think about hammering a nail into a 2 by 4. Lay a 20 oz framing hammer on a nail and nothing happens. Up it to a 16 lb sledge, and still we see only an indent in the wood fibers. Now swing away, and you get a feel for how much multiplication of load forces which existed as each successive level in the Trade Towers gave way.
Did they slow things down a little? Yes, a little, almost imperceptively.
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Wow. And all 58 columns were driven in identically! Even a slight perturbance would get amplified with each floor causing it to tilt and collapse.
Is there some reason why you, and others are so willing to completely dismiss any credible investigation? Not a rhetorical question, why are people so willing to just completely ignore the fact that a reasonable investigation was never done?
1. We all know now, with 20/20 hindsight, that Iraq was not involved in the 9/11 attack yet the very day of the attack Cheney tells his top advisors he wants this to be blamed on Iraq. (Perhaps raising the odds of this being an inside job from 1 in a million to 1 in 210).
2. We all know that Cheney had a classified, top secret meeting with all the Oil executives about 8-9 months prior to the attack. A meeting that was not ever scrutinized because unlike the President of the US, the vice president is not subject to the oversight of the Senate because he is not part of the executive branch of government?! However, Cheney and others do have a report in a high level think tank in which they say that they need to transform the military to a high tech armaments but without a Pearl Harbor like event as a catalyst this transformation will take several decades. (Perhaps raising the odds of this being an inside job from 1 in 210 to 1 in 21).
3. Regardless of how you try to explain what happened it is completely totally hypothetical and that is because the President of the US ordered the military to come in and seize and destroy all evidence. (Perhaps raising the odds of this being an inside job from 1 in 21 to 50/50).
4. Regardless of how reasonable you might think the collapse from an airplane fire is, the fact is there have been 100 major fires in steel high rise buildings that didn't result in a collapse. Many of these fires were far more horrific and burned for many more hours without collapse. (Perhaps raising the odds of an inside job to 20:1)
5. I always thought it took a very sophisticated demolition team to bring a building like the World Trade towers to collapse in on itself. So the odds of this happening by chance, that the fire knocked off the fire retardant on all 58 columns equally, and at the same time, and that an oxygen starved fire was able to burn hot enough to cause all 58 to fail at precisely the same instant, that is truly amazing coincidence. (Perhaps raising the odds of an inside job to 2,000:1).
6. But it gets better because it happened a second time on the same day. Wow! (Oops, make that 2,000,000:1)
7. But it gets better because it happened a third time on the same day, and this time without even an airplane crashing into the building. Triple wow. (Oops, make that 2,000,000,000:1).
8. We also know that the alarm was first blown by those brought in to investigate the collapse. They have claimed that key tests were not done, nor did they have access to the physical evidence. (Maybe 10 billion to 1).
9. So concerned were they that they did their own private investigation. In the dust they discovered evidence of thermite which would explain a fire hot enough to burn steel, it would explain a fire burning for a month, it would explain a fire that is 2,000 degrees, and it would not be explained by airplanes. (Perhaps 1 trillion to 1).