What I just dont get

Is how both towers collapsed.

To me it just doesnt seem like the weight coming down where the planes slices through the buildings would cause a full dominoe collapse. However as some people have stated, their was charged explosions set off, I think if you go many stories down and weakened the steel beams, then I can see why they collapsed all the way down. But since the planes hit relatively high, I just dont see how it made the entire buildings collapse without some aid further below that point.

My questions about 9/11 is.... Who are the people who died?

Were their people on these planes?

reply to post by sarentack


Yep.
And as for the collapse. Please remember 3-5 floors where comprimised on the impact alone.
And the weight did the rest after the supports were weakened enough by the fire.

[edit] The collapse mechanism
Owing to differences in the initial impacts, the collapses of the two towers were found to differ in some respects, but in both cases, the same sequence of events applies. After the impacts had severed exterior columns and damaged core columns, the loads on these columns were redistributed. The hat trusses at the top of each building played a significant role in this redistribution of the loads in the structure.[4]

The impacts also dislodged some of the fireproofing from the steel, increasing its exposure to the heat of the fires. In the 102 minutes before the collapse of 1 WTC, the fires reached temperatures that, although well below the melting point, were high enough to weaken the core columns so that they underwent plastic deformation and creep from the weight of higher floors. The NIST report provides a useful model of the situation.

“ At this point, the core of WTC 1 could be imagined to be in three sections. There was a bottom section below the impact floors that could be thought of as a strong, rigid box, structurally undamaged and at almost normal temperature. There was a top section above the impact and fire floors that was also a heavy, rigid box. In the middle was the third section, partially damaged by the aircraft and weakened by heat from the fires. The core of the top section tried to move downward, but was held up by the hat truss. The hat truss, in turn redistributed the load to the perimeter columns. (p. 29) ”

The situation was similar in 2 WTC. In both towers, perimeter columns and floors were also weakened by the heat of the fires, causing the floors to sag and exerting an inward force on exterior walls of the building.

At 9:59 a.m., 56 minutes after impact, the sagging floors finally caused the eastern face of 2 WTC to buckle, transferring its loads back to the failing core through the hat truss and initiating the collapse; the section above the impact area then tilted in the direction of the failed wall. At 10:28 a.m., 102 minutes after the impact, the south wall of 1 WTC buckled, with similar consequences. After collapse ensued, the total collapse of the towers was inevitable due to the enormous weight of the towers above the impact areas.

A combination of three factors allowed the north tower to remain standing longer, the region of impact was higher (so the gravity load on the most damaged area was lighter), the speed of the plane was lower (so there was less impact damage), and the affected floors had received partially upgraded fire proofing.[4]

From:Wikipedia: The WTC collapse

Wow, and you actually believe that yourself? I had to laugh when I read that.

Can you please answer the OP's question: why did the floors below the impact points collapse? They suffered no structural damage. Why could they suddenly not support the weight they had always supported?

Originally posted by WraothAscendant
reply to post by sarentack

 

Yep.
And as for the collapse. Please remember 3-5 floors where comprimised on the impact alone.
And the weight did the rest after the supports were weakened enough by the fire.

Not to discredit you or anything, but I would like you to conduct an experiment.

Take something like a cannon, load a can of soda into it and fire it at a 2 inch by say 6 foot long steel pipe.

See how that weakens the pipe or if it even leaves a mark. See what happens to the can of soda. Look at where most of the soda also goes, which will be all over the place on the ground several feet from the pipe.

Then take that same pipe and lay it in the hottest kerosene/paper fire you can muster, and report your findings.

Will the pipe melt? will it even weaken and bend? I'm POSITIVE the reult will be no.

I don't think people realize the mass of the steel support beams you are working with, and the structural comparison of a thin skinned aluminum aircraft over a relatively flimsy airframe. the planes disintegrated just like the soda can would.

The WTC would still be standing right now had there not been cutting charges/thermite or whatever have you employed. and there is no way there would have EVER been molten steel from a low-temp kerosene fire. I am sorry.

When last i checked they have never used kerosene as a means to melt steel, and in order for it to be close to weakened you would have to keep that heat localized over a small area, because in reality, the reason no steel structure will ever collapse from fire is because the heat does not stay localized, but rather travels through it like the heat sink that keeps the chip in your PC cool. In the WTC there was an awful lot of steel as a unitized structure to distribute this heat load.

heck with all of that heat and people standing and looking ou of the holes made by the airplane I would think the people would be gone before the steel also.

there is no way, a fire had anything to do with collapse, nor did it have anything to do with the impact of an airplane.

And additionally, there is no way they would have fell straight down. No way in hell.

With all due respect, there is no way, the planes or the short fires had anything to do with collapse.