Well ok it looks like this thread is getting off topic, so to get everything back on track here we go.
I’d like to open with popular mechanics thorough debunking; it goes through and tells the most up to date material.
Quote:
WTC 7 Collapse
CLAIM: Seven hours after the two towers fell, the 47-story WTC 7 collapsed. According to 911review.org: "The video clearly shows that it was not a collapse subsequent to a fire, but rather a controlled demolition: amongst the Internet investigators, the jury is in on this one."
FACT: Many conspiracy theorists point to FEMA's preliminary report, which said there was relatively light damage to WTC 7 prior to its collapse. With the benefit of more time and resources, NIST researchers now support the working hypothesis that WTC 7 was far more compromised by falling debris than the FEMA report indicated. "The most important thing we found was that there was, in fact, physical damage to the south face of building 7," NIST's Sunder tells PM. "On about a third of the face to the center and to the bottom--approximately 10 stories--about 25 percent of the depth of the building was scooped out." NIST also discovered previously undocumented damage to WTC 7's upper stories and its southwest corner.
NIST investigators believe a combination of intense fire and severe structural damage contributed to the collapse, though assigning the exact proportion requires more research. But NIST's analysis suggests the fall of WTC 7 was an example of "progressive collapse," a process in which the failure of parts of a structure ultimately creates strains that cause the entire building to come down. Videos of the fall of WTC 7 show cracks, or "kinks," in the building's facade just before the two penthouses disappeared into the structure, one after the other. The entire building fell in on itself, with the slumping east side of the structure pulling down the west side in a diagonal collapse.
According to NIST, there was one primary reason for the building's failure: In an unusual design, the columns near the visible kinks were carrying exceptionally large loads, roughly 2000 sq. ft. of floor area for each floor. "What our preliminary analysis has shown is that if you take out just one column on one of the lower floors," Sunder notes, "it could cause a vertical progression of collapse so that the entire section comes down."
There are two other possible contributing factors still under investigation: First, trusses on the fifth and seventh floors were designed to transfer loads from one set of columns to another. With columns on the south face apparently damaged, high stresses would likely have been communicated to columns on the building's other faces, thereby exceeding their load-bearing capacities.
Second, a fifth-floor fire burned for up to 7 hours. "There was no firefighting in WTC 7," Sunder says. Investigators believe the fire was fed by tanks of diesel fuel that many tenants used to run emergency generators. Most tanks throughout the building were fairly small, but a generator on the fifth floor was connected to a large tank in the basement via a pressurized line. Says Sunder: "Our current working hypothesis is that this pressurized line was supplying fuel [to the fire] for a long period of time."
WTC 7 might have withstood the physical damage it received, or the fire that burned for hours, but those combined factors--along with the building's unusual construction--were enough to set off the chain-reaction collapse.
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One big thing that is not mentioned is that the fireproofing that is sprayed onto some steel girders is easy to knock off with enough force; the impact of the planes would easily shake it off. This would also have happened in some places in wtc 7 from the impact caused by the debris from wt1. I know this for a fact because recently (about a year ago) we had an earthquake near where I live and it knocked off nearly half of the fire proofing in the mechanics garage where I work. It was only a 5.something and it was about 33 miles away. Fire proofing is designed to stand up to fire, not to impacts, its does break and fall off if enough force is applied.
Next I’d like to put to rest the controlled demolitions claim.
I’ll first start with the process of a controlled demolition. All the major support beams must be severed in order to get the building to collapsed, that means they beams must be exposed, cut part way to weaken them, and rigged with explosives. This explosive is usually a specialized explosive called RDX, encased in copper to make a chapped charge, which shoots a jet of hot copper to slice the beam. Then a secondary charge blows the beam a bit so it is no longer resting on the lower part but can fall. This whole setup needs to be applied to a lot of beams on many floors, that means they must cut through the walls to get to the beam, this just can’t be done secretly. It would take months to do, everyone in the building would have to be in on the plan, and it’s just crazy to think of all the logistics to destroying a building. Now I know you’re going to tell me if it only takes one girder to bring the tower down, why is it so hard to think it was a controlled explosion. The important girders were all on the lower floors, near the worst of the fire, next to the diesel, now how do you have explosives and fire in the same spot. Copper melts at 1084.62C, so were safe on temp for the metal, but RDX has an auto ignition point of 234°C, but that’s pure RDX, now they would probably use a plastic explosive, like C4 (which contains RDX) but C4 does not explode when its burned, it just burns, it burns very well. So there is another problem, if there were explosives set, they would need to be protected from the fires, so the workers would have to cut through the walls to plant the explosives, and then seal them back up and protect them from heat and fire. Back to the melting point of copper, copper melts at 1084 C so the fire would not necessarily gotten hot enough to melt the copper, but will a shaped charge work when very hot, no. when a shaped charge detonates, it forces the copper into a stream or jet that slices through the material, even though it has liquid properties, it is still not molten, but it is heated significantly, now it the copper was already heated, the extra heat from a fire and the charge would melt the copper rendering it ineffective. Next all the wiring would have to be shielded from heat, and any radio equipment for a remote detonation would also have to be dealt with in the same manner, to protect any remote equipment it would have to be incased in something, which would hamper any radio signal.
There were bad fires in tower 7, excessive damage from the collapse of the other towers, and thousands of gallons of diesel to fuel the fire. The fire fighters were called back because they were understaffed and could not cope with it, if WTC 7 was the only problem that day, it would still be standing, but the firefighters had been going since early that morning, and simply could not handle another fire to fight, not to mention the extreme instability of the building, they were right to not go into the building. Further more the building design was quite bad, allowing for a single column to bring the tower down, as stated in the NIST report.
Another thing I’ve been hearing a lot of is that no steel building has collapse before or after. Stating this as a reason that the towers should not have collapse is just stupid, its like saying no blimp before or after the Hindenburg has burst into flames due to static electricity, does this mean the helium lobby secretly planted charges inside of the Hindenburg to make it look like it was unsafe to suit there own agendas? No. It’s just that we have had very few experiences with these large steel buildings and never once before 9/11 has one been struck by a large plane. Never one has a moderately sized building had a huge building fall right next to it and then caught fire, and then have its fire suppression fail, and then have a bunch of diesel in the basement to boot.
http://en.wikipedia.org/wiki/Shaped_charge
http://en.wikipedia.org/wiki/RDX
http://www.popularmechanics.com/scie...tml?page=5&c=y
so how we doing willtravel?