Hans 183: Aah.
Actually, I believe that they were designed to survive an impact from a 707. Whatever that means.
And two, why are you arguing if none of this makes any difference? If the government did it regardless of any evidence to the contrary, what exactly is your point in complaining about specifics?
As with CMM, this is not a legitimate way to argue. Good faith requires the admission of the possibility, however slight, that evidence might prove you mistaken.
It appears that good faith you ain't got. I'd wish you good luck with that, but I wouldn't really mean it.Comment Posted By Troll feeder On 23.08.2007 @ 23:21
Hans 180: You do have an explanation of delayed collapse due to accumulation of fire damage. See 118.
What, exactly, do you think the core columns were made out of? Adamantium? They were as capable of failure as anything else.
The core columns did not directly support the mass of the collapsing upper stories. This avalanche landed in large part on the truss-supported, concrete slab floors which -- and I'm making a (pretty well-educated, see below) guess here again -- were not designed to support even the static weight of all the floors from above, much less the falling weight.
Non-specialized concrete weighs approximately 137 pounds per cubic foot (pcf) (Machinery's Handbook, 25th). According to the Wikipedia entry, the WTC floors were 4-inch concrete slabs on corrugated steel, supported by 35 or 60 foot long truss joists on 80-inch centers.
Ignore all of the steel; ignore the motion; assume only 15 floors worth of concrete evenly distributing their weight over the floor underneath. 15 floors times 4 inches is five feet of concrete thickness resting on the supporting floor. At 137 pcf, that equals 685 pounds per square foot (psf) on a floor that _might_ have been designed for 120 psf.
This only gets worse when you add in the structural steel, and the desks, and the copiers, and the partition walls, and the water coolers, and the localized loading, and the 10-plus feet of acceleration.
The trusses supporting the floors connected the perimeter wall to the core columns. The trusses failed with the floors and in doing so would have applied spectacular, localized, horizontal loads to the core columns. Columns don't like horizontal loads. Makes them unstable. Nothing really likes hanging out in a concrete and steel landslide, either, for that matter.
No disrespect intended, and I could go on with data on the allowable loads for steel truss joists, for instance, but at some point you need to demonstrate why the core columns should have been indestructible defenders against collapse rather than constantly demanding that someone explain why they would not have been.Comment Posted By Troll feeder On 23.08.2007 @ 23:08
Hans 170: The majority of the Towers was empty space. There would have been plenty of room for components to move around and past one another.
The second sentence is an opinion, of course. I have not modeled the collapse, so I do not _know_ this to be the case.Comment Posted By Troll feeder On 23.08.2007 @ 20:02
busboy33 153: I disagree with the degree of your assessment of the current Administration, but full on props for presenting a cogent argument. It was a pleasure to read.Comment Posted By Troll feeder On 23.08.2007 @ 17:56
CMM 137: you make unsupported claims regarding the amount and use of the fuel in the aircraft to bolster your conclusion that there was not enough fuel to cause significant fire damage. And then you demand that others provide "math to the contrary."
That is not how argument works. You have made a chain of assertions for which you provide no hard evidence, no legitimate references, and no actual calculations, though you claim to present valid results. No one on the other side of the argument has a duty to expend any effort to disprove such an unsupported claims.
You have the duty to prove your arguments correct; I have no duty to prove them incorrect. That I occasionally do so merely shows my good-natured committment to public service.
As Frank IBC 142 wrote, "YOUR calculations, please?"
Also, reference for instance, _The Looming Tower_, by Lawrence Wright, to learn more about bin Laden. He was first and foremost a fund raiser and conduit for jihadi operations.Comment Posted By Troll feeder On 23.08.2007 @ 12:15
Hans 110: Sorry for the previous snarkiness.
From a standing start, an object will fall about 1600 feet in ten seconds. The towers were about 1350 feet tall, ignoring the spires. The collapse of the buildings in about ten seconds does not, therefore, seem unreasonable.
The collapse starting an hour after the initial impact is explained by accumulation of damage due to the fires.
Structures don't collapse when they are set on fire. Rather, they collapse after the fire has inflicted enough damage that the building can't support itself anymore. Or part of the building cannot support itself anymore, and the failure of that part destabilizes other parts until the entire structure collapses. The straw that breaks the camel's back, as it were. Why should this be true for all other structures, but not for the Towers?
Yours is the first claim I have ever seen of neatly cut pieces of steel. The massive rubble pile I saw included dust, rubble, and twisted steel. Are you looking at a different set of collapse pictures than everyone else?
Why would the collapse of the buildings not have resulted in projectiles flying all around? If the buildings fell in 10 seconds, parts of them were moving at over 100 mph. It would be unbelievable had debris not sprayed all over the place.Comment Posted By Troll feeder On 22.08.2007 @ 23:14
Eric Wilds 112: My bad. I'm just so used to materials taking on the temperature of their surroundings that I simply assumed that steel hanging out in a 1000 deg F fire for an hour would approach that temperature itself.
Silly of me.
Furthermore, I work for the oil industry, not the government. We're 238% more evil, and we demand full credit for it.
Hans 110: 49% of yield strength material cannot support 66% of yield strength loads. How much more elementary of an explanation do you need?Comment Posted By Troll feeder On 22.08.2007 @ 22:34
Hans 89: You have no way of knowing that the jet fuel burned off in a few seconds. Really. Regardless, the jet fuel accelerated the ignition of the combustible material inside the building, which did continue to burn.
I conclude that the fire heated significant portions of the building structure to significant temperatures because the towers were on fire across multiple floors from the time the planes hit them until they collapsed. You have seen the video, haven't you? The fires were quite clearly not localized to any appreciable extent. Even assuming that they were, the buildings were integrated structural entities; a significant, local failure could easily have initiated a progressive, general failure.
The planes traveled through the buildings. It is not particularly rational to claim that they managed to do this without to some extent damaging the core columns that they had to get past. Nor is it rational to claim without caveat that core columns could withstand the failure of the structural members attached to them. Particularly the eccentric failure of such members.
Sure the columns were designed to support a lot of weight. The were called upon to resist the impact of a 15-story-building-sized hammer. These are not equivalent load cases.
You suggest that I ask an engineer....hmmm. OK. "Troll feeder, would the top of the building topple sideways?" Only if there were an inclined plane or horizontal force pushing it to the side, because gravity mostly acts in a downwards-type direction.
"Troll feeder, would the top of the building fall a few floors and then become stuck in the core columns?" How should I know? What's the design of the columns? What's the load coming at them? I'll stand by an answer following modeling and testing, not before. Opinion-wise, though, sure, it's possible that the columns might have survived the impact from the top 15-plus stories avalanching down around them. Probably about as possible as the piece of straw getting rammed through the telephone pole by a tornado, but possible is possible.
Frank IBC 92's comments regarding concrete pretty much cover that topic.
So, Hans 89, let's recap your apparent reasoning for why the "impact and resulting fire initiated progressive structural failure" explanation is wrong:
You claim that the fires were small and irrelevant.
You claim that the failure of the non-core-column steel and concrete is insignificant to the structural integrity of the building.
You imply that the core columns were made of unobtainium and, thus, capable of resisting any level of impact loading.
To paraphrase Eddie Murphy, some of you who don't know much about engineering will continue to say, "I disagree."
Fair enough. I wouldn't presume to lecture Rosie O on how to run a TV show. I would suggest that she and you could learn something from that example, though.
And, thanks, Tyras 98.Comment Posted By Troll feeder On 22.08.2007 @ 22:14
Hans 69: Steel does not have to melt to become structurally useless. It only has to be heated to a temperature where its remaining strength falls below the loads applied to it.
The WTC towers had airplanes slam through them breaking or deforming some of the structural elements helping support the weight of the buildings above the impact sites.
The fuel and flammable materials of the buildings and airplanes burned across large sections of the buildings reaching temperatures estimated to be 1000 deg F at a minimum. 1000 deg F is well above the temperature necessary to reduce the strength of the remaining steel support members to levels below the UNDAMAGED design loading for the buildings, much less the damaged loading.
In addition, heated concrete dehydrates. In non-technical terms, water molecules in the form of steam are driven out of the matrix formed during the concrete curing reaction. The released steam expands inside the solid concrete causing the concrete to crack and spall. Thus, the concrete structural elements fail under extended fire exposure, too.
So, you have a loss of steel and concrete structural elements due to the initial impact, a partial loss of strength in the remaining steel elements due to heat "softening" -- NOT MELTING, and a near total loss of strength in any high-temperature concrete elements due to cracking and spalling.
The impacts were not enough to fell the buildings, but the impact damage combined with the hour of uncombated heating across wide swaths of the buildings was. No bombs required; no space lasers; no alien death rays; no melted steel. Just eight evil men and a pair of airplanes.Comment Posted By Troll feeder On 22.08.2007 @ 15:10
Any of you silly buggers going to address post #43? The rest of your garbage is just the internet version of the telephone game.
I know that 43 includes references and math and percents and stuff, but it is all verifiable by independent, third parties. Even you folks could confirm it with a minimum of research and calculation.
Unless the scientists and engineers have all been in on it for the last 100 years, falsifying all their data and chart publications so that the Mossad and Cheney with his evil, death-ray eyes and Halliburton with their money-grubbing, space alien contacts could invade Iraq and Afghanistan for ____ (fill in your reason du jour).
So put up, shut up, or admit that you are really only interested in demonstrating Swift's contention that one cannot reason a man out of something that he did not reason his way into.Comment Posted By Troll feeder On 22.08.2007 @ 12:47