M.O.A.B wrote:
rammunition wrote:
its interesting what happened to building 7, i am a Engineering student btw and i did ask one of my lecturers at college is it possible for fire to demolish a building, his reply was no and he does have a few doubts aswell.
I'm pretty sure fire can demolish a building, for exmaple, extreme heat melting the steel support beams holding up the floors therefore leading to a collapse.
Yes, fire can demolish a building. What you have to understand is that it takes EXTREME heat to melt steel. Steel is designed to act either elastically or plastically. If steel is loaded beyond its yield point, it will start acting plastically until it reaches its breaking point. Steel actually acts surprisingly well in fire,
British Steel and the SCI did a test ~ 10 years ago, they purposely built a huge shed (like an aircraft hanger) and then built a multi-storey building inside (I believe it was 3-4 storeys high)...just to test it. It came out very well, previously having believed that he critical point was ~ 550degrees C...but tests showed the steel in excess of 800degrees C in some instances, and it didnt collapse.
Steel is usually given a 1hour fire protection rating in modern structures, which can be increased by, say, encasing it in concrete or boarding it out. For MOD buildings, I believe they have to have 2hours of fire protection.
You are also forgetting about progressive and disproportionate collapse, as well as tying forces. Back in the 60's, a 30storey block of flats in London had a gas explosion in a flat near the top: every flat below it all the way down to about the 3rd floor was also blown away, and thats because the building wasnt properly tied (this is accounted for in the connections).
What Im trying to say, is that even if a connection, the load spreads elsewhere. A building is never designed to work 100% efficiently, you build in safety factors of up to 1.6x the load to design steel members: and then the member would likely be working at anything between 50-80% of its capacity. That beam will be designed to resist such forces as shear and bending moments. Connections will then be designed, and they will probably be working at 50-80% of capacity, which means that there is, again, a safety factor built in. So lets say that 6 columns, all in a square, all failed, then yes, it probably would lead to collapse.
However, for that happen, requires a TREMENDOUS increase in force (we are talking several hundred tonnes) which, short of a plane packed with explosives hitting the building, I honestly cannot see happening. The building didnt get plastered in highly volatile jet fuel and set alight, and the damage the building took from the collapse of the north (?) tower wasnt that substancial: it was more damage to the outside face, which contributes nothing to the structural integrity of the building. If anything, if it has lost some of its outside facade, the frame is supporting less load.
Not only that, but lets say that a part of the collapsing tower hit WTC#7, where would it hit? The roof. If part of the roof collapsed, this wouldnt cause failure of columns and/or beam and their connections, because a roof is designed to take snow loading (very heavy). If you think debris falling 100ft, to smash through the skin of the roof will somehow cause a column down on the middle floor to fail, you are wrong.
That many columns and/or beams simply could not fail in that manner unless there was something extra involved that we dont know about (on purpose or something legit happened that nobody saw). Perhaps something as "innocent" as say, the wrong grade of steel used (higher grades = stronger in certain aspects). Different grades of steel have different carbon contents (Parker has already touched on this). If an incorrect grade of steel was used for a series of columns/beams...it is already going to be acting differently than what it should be (the only way, to my knowledge, that it is identified, is a sticky label or hardstamp on the steel itself).
Now, to my mind, to heat up enough steel to cause structural failure, would require HUGE temperatures across the entire building.
If fire was the actual cause of structural failure of the building, then, as I say, you would need extreme heat, we are talking in excess of 1000 degrees C. Some random arsonist fire will not reach 1000degrees C without some catalyst to spur the fire on and seriously heat it up. Office paper and furniture would not get up to that sort of temperature. I think the fact that they found traces of Thermite Plasma on the steel kinda suggests something dodgy too - it was on BBC two weeks ago after Top Gear, and they actually showed the results analysed in the lab. Fire has never levelled a steel-framed skyscraper before or since this incident.
Remember: no plane hit this building, and up until the north tower collapsed, very little falling debris hit the tower (why would it?)
Somebody please explain to me how Thermite Plasma gets into a building, goes through all the walls and internal build'ups and gets onto the skeletal frame of the building, without somebody physically doing it themselves. Remember that WTC#7 was home to a lot of the top intelligence services...all in a single building. I find that rather...shocking, in all honesty. Shame BBC iPlayer only does the last weeks worth on TV.
I dont believe in conspiracies, however, WTC#7 and the Pentagon, when you see the evidence, does make me wonder if theres something else that isnt being said.
Edit: Incorrect dates for the cardington fire tests.
Last edited by Snake (2008-07-16 13:12:58)
