why did it fall through itself, instead of falling over? Even if the beams were soft they would still offer some resistance, wouldn't they. I just can't understand how all the support columns could melt at exactly the same time.
2007-02-14 15:33:25 · 10 answers · asked by Anonymous in Politics & Government ➔ Other - Politics & Government
As each floor collapsed, the weight accumulated, and that much more weight fell on the next floor below. Because gravity pulls straight down, the path of least resistance was straight down.
2007-02-14 15:44:56 · answer #1 · answered by Restless 3 · 2⤊ 2⤋
Despite what some people say, there were no bombs or anything like that. They need to understand how a fire works, and they need to understand the structure of the WTC.
If you look at the structures, they were basically two super-size chimneys, with a large portion of the support on the perimeter of the building.
The fuel of the aircraft did not stay in the vicinity of the crash. A huge quantity of the fuel spilled down the elevator shafts in the center of the buildings, causing all that smoke people reported seeing at the base of the towers. Basically, the entire tower was on fire, and not just the impacted floors.
Elevators and other equipment falling created the sounds of explosions at the base of the towers. Also, the heat from the fire throughout the entire building created a dry vacuum, creating less resistance for the block that was about to fall down on it.
Once the impacted floors weakened, the weight of the upper floors compacted onto the next floor, and the next, and the next, which is why it sounded like a series of explosions. Each floor literally exploded from the weight of the upper block falling on top of it.
Remember, there was nothing there to cause the upper floors to crumble. It was one big block of reinforced concrete and steel, so the entire upper section was coming down as one big block.
If you weigh about 120 pounds or less, try this experiment: Gently stand on top of an empty soda can, ensuring you don't crush it. While standing on it with one foot, bend over and quickly tap the sides of the can. Be sure to retract your fingers quickly. You will end up with a can perfectly crushed top to bottom. That's basically what happened to the towers.
As for tower 7 falling as if it were in a vacuum, well, it basically did. The building internally was on fire for a long time. The heat displaced the air and humidity, creating a virtual vacuum inside relative to the cooler, humid air outside. As the building began to collapse, video shows the external walls and windows expanding, creating more of a vacuum inside. The building collapsed quickly, the solid cement filling the void inside, with the heavier air outside helping.
2007-02-15 00:17:25 · answer #2 · answered by scavenger_meat 3 · 1⤊ 2⤋
This is the most comprehensive explanation that I've seen yet.
http://web.mit.edu/civenv/wtc/PDFfiles/Chapter%20VI%20Materials%20&%20Structures.pdf
But specifically, page numbered 92, page 10 of the pdf explains why the buildings could not simply tip over.
The columns did not need to "melt" In brief, as the floor systems failed, the columns buckled and failed. It is a progressive collapse. Although I did not see the term used in the paper, the buckling is caused by "slenderness ratio” Basically although a columns or series of columns may be able to handle the compressive load, they may buckle under sufficient load, when lateral support is removed. A practical example would be to compress a foot long slender piece of wood, smaller in cross section than a pencil. Support the middle of the wood with your fingers, just to keep the wood from buckling. If you remove your fingers, the wood buckles. Because you had lateral support, the wood didn't fail, but when you remove the support, it buckles. Your fingers weren't adding any compressive strength to the wood, just preventing the wood from buckling.
The interesting thing is I saw a video close up of the columns just below impact on a conspiracy theory website. The columns were visibly buckling, just prior to failure, reinforcing the progressive collapse theory. I wish I had bookmarked the page.
Also, as far as creditability, note the authors of the paper. Professors of civil engineering, which encompasses structural engineering and material engineering. At MIT.
http://cee.mit.edu/index.pl?id=2381
http://cee.mit.edu/index.pl?id=2288
2007-02-15 01:56:30 · answer #3 · answered by robling_dwrdesign 5 · 0⤊ 1⤋
What would be the force that tipped it over?
Gravity pushes down...not sideways
One a few columns went, the remaining were not enough to hold the weight of the building
Demolition experts take advantage of this fact and let a building collapse itself by blowing out a few key columns at the bottom...the momentum of the falling building does the rest
Any engineer understands this fact...as I read the answers above, I see the ignorant masses lamely try to blame the government again...why don;t you idiots go live in the middle East with the other idiots?
2007-02-14 23:40:54 · answer #4 · answered by Anonymous · 1⤊ 3⤋
It's called "engineering" mr. hollow man...Remember those earthquakes in San Francisco and L.A.? Structures built before 1960 toppled over, while modern structures collapsed straight down...as they are designed to do to limit wide-area damage.
Now, go eat your peach and be gone...
2007-02-14 23:47:55 · answer #5 · answered by u_bin_called 7 · 1⤊ 2⤋
Well the buildings IMPLODED because when the planes hit it went in more than half of the way into the buildings, and near the top, so when the first floors colapsed they caused a chain reaction.
2007-02-14 23:43:47 · answer #6 · answered by Anonymous · 0⤊ 3⤋
It just falls into the category of one of those strange coincidences.
2007-02-15 00:02:11 · answer #7 · answered by michaelsan 6 · 1⤊ 0⤋
When the bombs that were pre-planted in the buildings went off, the path of least resistance changed to straight down
2007-02-14 23:38:43 · answer #8 · answered by Anonymous · 2⤊ 5⤋
the fact that you think anything "melted" tells me that you have no idea what you are talking about, nothing had to melt, you just have to heat up tensile steel a bit weaken it
2007-02-14 23:55:51 · answer #9 · answered by Nick F 6 · 1⤊ 2⤋
Because the World Trade Center was a controlled demolition created by the CIA to get us into Afgahnistan and Iraq.
El
2007-02-14 23:37:35 · answer #10 · answered by El_Nimo 3 · 3⤊ 6⤋