The media never talks about it but there were 3 trade centers that collapsed on 911 (1,2, and 7). If you go to google video and type in WTC7 collapse you could see it. I'm really interested in this and I'm not a conspiracy nut but all I know is that no steel frame building in the history of man has ever collapsed from fire except for that day.
2006-10-21 08:08:31 · 13 answers · asked by Peter F 1 in Science & Mathematics ➔ Engineering
Classic demolition.
An inside job.
WTC7 housed the computers whuch were controlling the explosions in the other vtwo buildings, as well as lots of FBI evidence relating to corruption, and disappearing money. It was to the perpetrators benefit to have it all destroyed.
2006-10-23 03:36:31 · answer #1 · answered by Anonymous · 0⤊ 1⤋
I don't know where you get the idea that "no steel frame building in the history of man has ever collapsed from fire". That is the most uninformed comment I've ever heard.
Stuctural Steel doesn't have to reach any where near its melting point to fail under load. One of our companies buildings burned just the other day and almost collasped. It was a single story building and only burned for a few minutes. The local building officials required an inspection by a structural engineer and several structural members had to be replaced before we could occupy the building. Steel channels and angle irom members of trusses were warped and distorted.
In the case of the WTC steel joist supporting the floor above the fire failed and collapsed crushing the floor beneath and so on. But that was only the start of the collapse. It doesn't take a structural engineer or a genius to understand that the floors provided lateral support to the columns holding up the dozens of floors of building above.
The importance of laterial support to columns is pretty simple to understand. If I have a piece of steel 1/4" in diameter and its only 1" long it would easily support 500 lbs. But if I took the same piece of steel, in fact more of it 10 ft long it wouldn't support its own weight vertically and would bend over. When enough of the interior floors broke free inside the WTC the outer columns lost their laterial support and buckled (collaspsed) Allowing the dozens of upper floors to come crashing down. Once they had fell only a few feet the momentum of such weight was virtually unstoppable and crushed the lower floors. Then the sudden stop at the bottom allowed the upper floors to crush themselves.
I don't know why this is so hard to understand?
2006-10-21 09:58:21 · answer #2 · answered by Roadkill 6 · 2⤊ 0⤋
Honestly stop listening to all the conspiracy nuts. Everytime anything newsworthy happens some wacko comes up with their "theory". The reason you dont hear about WTC 7 is b/c it was a smaller building than the towers and it wasnt hit by a plane. The WTC was a complex of buildings but the focal points were the two tall towers. As far as steel buildings collapsing go, I dont know if your statement is correct as to them being the only steel buildings to collapse from fire. But if that is the case, I would say that it happened b/c of the shear magnitude of the fire, the shear size of the building, and most importantly planes hit the towers. I would say that in the history of man there has never been such a scenario such as that and to me that would explain it. One point that the conspiracy theorist dont tell you- steel begins to lose strength at 200 degrees. It doesnt melt, but it loses its rigidity and thereby loses the ability to support structurally. By the way I am a civil engineer.
2006-10-21 13:47:20 · answer #3 · answered by ms mystery 3 · 1⤊ 0⤋
I don't know about building 7, but I heard the twin towers collapsed for the following reason. When the buildings were constructed, to save weight, the steel structure was sprayed with a lightweight fire resistant material, instead of using more durable concrete. Thus, the fire protection material was blown off the steel In the initial collision. The large quantity of jet fuel created a very hot fire. Also, the fuel contained sulfur, which combined with the steel to make a eutectic alloy; in other words it lowered the melting point of the steel...and critically weakened the structure. The building was designed to pancake as apposed to tipping-over. etc etc.
2006-10-23 15:30:31 · answer #4 · answered by _ 3 · 0⤊ 0⤋
Imagine building a card tower with five plus stories. Now build a card town one story tall next to it. If you knock over the five story tower would you be surprised if the one story tower fell? I wouldn't.
The is basically the same thing as the WTC 7 collapse expect you are talking about real building. Yes do realize that real buildings are more stable than card towers but they also have a lot more mass. And the two things cancel out.
2006-10-21 09:19:55 · answer #5 · answered by sparrowhawk 4 · 0⤊ 0⤋
It happens to be the first case of a sky-scraper that's collapsed exclusively because of fire. The collapsing of the structures around it caused a fire in the huge diesel storage tanks in #7's lower levels.
BTW At the time I worked across the street. The new #7 was built a bit to the west of the old one.
2006-10-21 08:20:27 · answer #6 · answered by JAT 6 · 1⤊ 0⤋
I think the main reason it collapsed was because a lot of the debris from the two main towers fell onto it. The heat of the fire was not enough to melt the steel support, but it weakened it enough so that with the additional weight from debris the building couldn't stay up.
2006-10-21 08:13:59 · answer #7 · answered by bpc299 2 · 2⤊ 0⤋
i think the big collapse of two building happened because the amount of fuel and airplanes main material aluminum can react violently with iron and melt the iron bars all this weight make the upper part knock down the lower part and big collapse after that can hurt any building close to the location
2006-10-21 12:05:18 · answer #8 · answered by source_of_love_69 3 · 0⤊ 1⤋
the fire from the other buildings falling on it caused it to burn, but the thing was the firefighter didn't want to waste time on that building since everyone got out, so they let it burn, and it fell down..
2006-10-21 08:17:19 · answer #9 · answered by Anonymous · 0⤊ 0⤋
hmmm... lets see.... big building right next to smaller one collapses. Little one in pathway of falling building... little one go boom and fall too.
2006-10-21 08:16:52 · answer #10 · answered by wizardslizards 4 · 2⤊ 0⤋