There were a number of materials used in building the WTT (World Trade Towers): concrete, steel, aluminum, and glass making up the majority of the material. The towers collapsed on 9/11 because the steel support structures were heated to the point that they bgean to bend and then collapsed, with the end result being that the top floors of the buildings pancaked down on to the floors below, creating a domino like affect. There was some fire-insulating material on the support beams, but much of it was knocked off by the force of the airliners impact into the buildings.

All the information you could ever want on the World Trade Center disaster can be found here: http://wtc.nist.gov/ . This report covers the impact damage: http://wtc.nist.gov/NISTNCSTAR1-2.pdf . Be patient while downloading; it is 462 pages long. The primary findings of this report are found beginning on page cix of the executive summary (111 of the PDF document). NIST is the authoritive source on the subject - all reports by all investigative teams were funded by and delivered to NIST. One noted concern during the failure analysis was to identify the reasons why one building survived about twice as long as the other. A few points: - The buildings had quite a large safety factor in their design. - The impact damage on its own did not cause the failures, but contributed to them in several significant ways. - A normal fire (closed building) would not have caused the failures. - The fires that precipitated the failures were exceptionally severe because of the wide distribution of fuel following the impacts, the wide distribution of burning or flammable debris, and the large impact holes in the buildings which provided an oxygen supply that would not have been present in a fire in a closed building.

Part of the reason the fire-insulating material was blown off was that the steel was painted prior to the insulation being applied. If you look at the pictures of the trade centers in the fema publications you will notice the steel is red. Red steel (painted steel) is not needed and not supposed to be used inside the buildings. The insulation was tested on bare steel - and does bond much like conrete to bare steel - but not painted steel. This is something everyone has chosen to overlook. - Any reporter types out there should look into this. They might of come down anyway - but I don not understand the other experts glossing over this fact.

The reason for the collapse: detonation charges placed on base. There is no way jet fuel would collapse a building. A Spanish building burned for more that 24 hours and it did not collapse so did a Latin-american building. WTC is the first building in the history of manking to collapse because of fire.

Without for a moment subscribing to any of the conspiracy theories surrounding the attacks, it seems obvious that something was a little odd about the collapse of these two buildings. They were supposedly designed to withstand being hit by airliners; yet on 9/11 they collapsed within a very short time after the airliners being crashed into them. I fervently hope that material scientists and architects are properly studying what really happened so they can prevent something like this from happening again.

Strategically place explosives will bring down any building in the usa. 911 wtc example of a perfect demo. http://vincentdunn.com/wtc.html

I watched a very good program on the Discovery Channel that explained the whole thing. There is no need to bring in any outside conspiracy theories, or such. The wikipedia article is well researched and has many excellent resources for you to check. This is not really a subject that can be adequately covered on this forum. http://en.wikipedia.org/wiki/Collapse_of_the_World_Trade_Center

It has been discussed at lenght already and I am not a builder not an engineer. But if you have ever seen how they demolish buildings, they knock the bottoms off so the building will collapse and turn to rubble unde its own weight. By looking at the vids, this is what happened: if just one floor is obliterated and there is enough weight on it then the weight will do the rest. Imagine a few floors of rubble falling onto one solid floor, the floor will collapse and add to the overall weight so next floor down will be even easier to crush, and so on till ground floor. RIP them all poor souls, shame and enernal damnation on the responsible ones.

thermite Check ae911truth.org It's an organization of very impressive group of scholars that have looked at the scientific data and contrasted with the official story's rendition of events. There are many important differences that any true american should look into with strict discernment. "Why was there Molten Metal Under Ground Zero for Months after 9/11?" One good example of why the offical story that the government has fed the public is strange is that jet fuel is 4/5ths kerosene and if you have a gas stove and you leave it on for hours and hours the steel on the stove does not melt... In order to turn the steel into dust you will need something that burns something much hotter... There were infrared pictures taken from satellite that showed that there were temperatures that were much higher than that which jet fuel burns for weeks after the attacks... These are questions that have been asked by the public many times and has always resulted in persecution. The mainstream media hasn't even mentioned these facts, which leads me to think that that the media is bought and paid for by the government... Not to say that the government is all bad, but I do think that there are aspects of the government that act without public consent which is what is supposed to make the U.S. a democracy.... Even if they thought that to continue our empire it is worth the sacrifice of 3,000 civilians they would still have to check with congress and our representatives to see if such a course of action would be condusive, but they appear to have done the opposite without taking modern technology into account... The fact that an event can happen in one part of the world and be reported on the other side of the globe instantaneously is so effective, and I think the secret influential powers were so power hungry that they did not take this into account.

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In 2 months it will be the 40th anniversary of the Moon landing. The WTC was destroyed 70 years after the Empire State building was completed. Skyscrapers are not rocket science. It is pathetic that the nation that put men on the Moon has this 9/11 Psychosis after nearly 8 years. Skyscrapers must hold themselves up through their entire heights. Why don't we have a table specifying the TONS of STEEL and TONS of CONCRETE on every level of the towers by now? The NIST won't even tell us the numbers and weights of the exterior wall panels that supported 50% of the buildings' weight. The top down gravitational collapse business is nonsense. http://www.youtube.com/watch?v=LXAerZUw4Wc psik