treegod wrote:Thanks, Bsbray. That makes a whole lot of sense to me.
I'm guessing the pancake effect must be what I imagine to be and accordian?
Yes. This is a phenomenon associated with poorly-built concrete structures where the floors just fall one on top of another like a stack of pancakes. If this happened with the Twin Towers then you would have a large stack of floors at the foundation of each building, but instead the most you had in either case was a short stub of the core structure with no floors on top. Anyway this just isn't something associated with steel-framed high-rises.
I may be being really naïve or unbelievably cynical or both, but I can't actually see what the problem is. Help me out here. The towers were hit by aircraft. The aircraft were hijacked by terrorists. The towers unsurprisingly fell over to great loss of life and property. A truly terrible thing had happened and it might be someone's fault, so much @rse covering by the US administration, what a shock. The end. Surely.
I read once that one of the most convincing arguments that the Catholic Church made against the Earth orbiting the Sun, is that if the Earth really orbited the Sun, it would have to be traveling so incredibly fast through space (and it is
undeniably traveling incredibly fast) that severe hurricane-force winds would constantly be generated throughout our atmosphere that would constantly be blowing down buildings and blowing people off the face of the Earth. Therefore, the Earth must be relatively stationary and the Sun and other bodies are moving around the Earth, which makes sense anyway because God created the Earth for mankind to live on, and mankind is God's greatest creation because we were created in His image.
I realize you're probably not a Christian (and certainly not living in the Medieval era) and I hope you don't take offense to the comparison. The problem with ideas like this is that they make so much sense intuitively (within a certain worldview, anyway), that they're hard to argue against. If something just sounds like it makes so much sense, why go through so much trouble to question it, especially if it means you might even come across challenging things you wouldn't want to hear or know about in the first place? It takes looking at a lot of details to make this kind of picture ultimately seem impossible, but we can still get there, because obviously that argument against the Earth revolving around the Sun was wrong, and in this case what NIST published is also demonstrably wrong -- by their own data.
So in this case one could point out first of all that the planes alone did not bring down either tower or else they would have collapsed instantly. No one is arguing that the planes alone did
bring down the buildings. Okay, so we move on. It must have been the planes and
the fires. This becomes interesting. Steel-framed skyscrapers are actually very resistant to fires, and such a catastrophic collapse was a new phenomenon (and still hasn't been seen since), so we should study this just to understand how this could be possible, so we can protect buildings from these types of failures in the future
. It's not just about the politics of 9/11 and what exactly happened there, but this is potentially a huge weakness of all steel-framed skyscrapers that we never knew of before, and there are hundreds of steel-framed skyscrapers in big cities all over the world that regularly experience fires. See how scary that is?
There was a structural engineer who was part of the original FEMA BPAT team and who testified before Congress later about this initial study. His name is Abolhassan Astaneh-Asl and he's a professor of civil engineering at the University of California in Berkeley. He then went on to do indpedent studies on the problems of the building collapses on his own. It took him a few years but he finally figured out that something really weird was going on here.
This is probably the only time you'll see me link to Fox News as if it's credible, but this was actually an Associated Press article and I can't find any other websites besides forums that are mirroring it:
http://www.foxnews.com/story/2008/03/25 ... s-katrina/
NEW ORLEANS —
The professional organization for engineers who build the nation's roads, dams and bridges has been accused by fellow engineers of covering up catastrophic design flaws while investigating national disasters.
After the 2001 attack on the World Trade Center and the levee failures caused by Hurricane Katrina in 2005, the federal government paid the American Society of Civil Engineers to investigate what went wrong.
Critics now accuse the group of covering up engineering mistakes, downplaying the need to alter building standards, and using the investigations to protect engineers and government agencies from lawsuits.
Similar accusations arose after both disasters, but the most recent allegations have pressured the organization to convene an independent panel to investigate.
In 2002, the society's report on the World Trade Center praised the buildings for remaining standing long enough to allow tens thousands of people to flee.
But, the report said, skyscrapers are not typically designed to withstand airplane impacts. Instead of hardening buildings against such impacts, it recommended improving aviation security and fire protection.
Abolhassan Astaneh-Asl, a structural engineer and forensics expert, contends his computer simulations disprove the society's findings that skyscrapers could not be designed to withstand the impact of a jetliner.
Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers.
He also questioned the makeup of the society's investigation team. On the team were the wife of the trade center's structural engineer and a representative of the buildings' original design team.
"I call this moral corruption," said Astaneh-Asl, who is on the faculty at the University of California, Berkeley.
Gene Corley, a forensics expert and team leader on the society's report, said employing people with ties to the original builders was necessary because they had access to information that was difficult to get any other way.
Corley said the society's study was peer-reviewed and its credibility was upheld by follow-up studies, including one by the National Institute of Standards and Technology.
"I hope someone looks into the people making the accusations," Corley said. "That's a sordid tale."
What this article doesn't mention is that Mr. Astaneh-Asl simulated aircraft impacts into several different New York City skyscrapers and found that all of them could withstand the impacts and prevent severe fires. Also this article never went anywhere else, so I guess neither did the Congressional investigations. That doesn't mean there was no cover-up of course, especially since even members of the Kean Commission (9/11 Commission) have since stated that they were stonewalled and that their report was a political whitewash, and they were only spoonfed certain information.
If you want to get into the specifics of the NIST report in particular, it's like I said in the post above.
Here's the trusses and perimeter columns:
http://911research.wtc7.net/essays/reyn ... russes.jpg
NIST's hypothesis is really pretty simple. Their hypothesis is that the fires heated the trusses. The trusses "sagged," as steel will do when sufficiently heated. When the trusses sagged, this is where it gets kind of fuzzy for NIST, at least in the technical details. The suggestion is that the sagging caused the perimeter columns to be deflected, as the trusses "pulled" on them. Here's the problem: the sagging is caused by the truss trying to expand (thermal expansion -- the steel gets hotter and tries to expand), which is really causing a pushing
onto the perimeter columns. (This is why FEMA had trouble deciding if the trusses were pulling or pushing, the two completely contradictory motions. NIST decided that the photographic evidence was more in favor of the perimeter columns deflecting inwardly, which is debateable, but nonetheless this was their conclusion.) So the trusses sag because they are trying to expand but the perimeter columns are firmly in place, leaving the expansion nowhere to go but in the center of the truss, causing it to bow outward in the middle.
In physics classes you have to draw free-body diagrams, so if you've done this just try to imagine this picture. You have a truss trying to expand from thermal expansion. It can't expand evenly because it's held firmly in place by the perimeter columns, so it bends in the middle instead. How does the outward-pushing thermal expansion, which caused the bowing in the first place, result in an inward pulling
of the perimeter columns? Now that's a pretty good puzzle, isn't it? In fact it makes absolutely no sense, but it's buried so far into the technical details of this report that unless you're actually trying to read this 10,000+ page report to make sense of it, you'll never even see it. Most of all of those pages, by the way, are absolutely nothing to do with this hypothesis. They discuss just about everything else you can think of, like at what time people went down the stairwells while evacuating.
NIST did lots of tests and simulations, and the heat and temperatures from the fire would pretty obviously not be enough to weaken the columns directly. Strength loss due to heating simply wouldn't cause enough loss of integrity even on the floors where the planes had caused the most damage (something like a loss of 13% of the perimeter columns on those floors, probably much less of the core columns -- NIST determined only engines could have taken out the core columns, maybe 1 each, out of 48 or 49). This is why they had to go with the truss deflection theory in the first place. Instead of the columns losing integrity due to heating, they lost integrity (according to NIST) because the trusses got hot, and while trying to expand, pulled the columns inward somehow, and this deflection from the inward pulling is what caused -- eventually -- enough integrity to be lost to initiate a "global collapse sequence." Once NIST reaches this part in theory study, they call it a day and don't attempt any sort of analysis whatsoever on what exactly happens after the "global collapse sequence" begins, which is when everything starts moving as you see on all the videos of the collapses.
Also as I mentioned before, while NIST was testing their hypothesis in the early stages of their report, they put some megawatt burners under a replica of the truss/perimeter column setup and put a lot of heat onto the assembly, until the trusses were glowing red hot. They were expecting to see the trusses deflect the perimeter columns, but this didn't happen. So this became a "calibration" for computer modeling, and no further physical tests were done. So everything from that point forward was carried out on a computer, and all the simulations were trying to achieve was a certain amount of sagging in trusses from being heated so much. I have yet to see anywhere in their report how they translate this sagging into an amount of force applied to the exterior columns or even a reasonable amount of deflection that it could achieve. They only show pictures where they try to measure visually how much the columns in the towers were actually deflection, which says nothing about how
this happened, and the scientific method demands that they recreate this for their hypothesis to be validated.
Anyway this is getting very long so I hope this helps explain my thoughts on this. Aside from all of this, NIST also failed to publish all of the details necessary for other engineers to do their own simulations and check NIST's work. So though they did not do any more physical tests besides the "calibration," even their computer modeling is not reproduceable because they didn't provide their data. If someone wanted to do any kind of analysis on the WTC Tower structures they would be unable to do so, because not enough data was published in the NIST reports. Out of 10,000+ pages you'd think there would be enough for their peers to actually be able to review their analyses independently, but this is one reason why they're now being sued. They've been issued multiple FOIA requests and still haven't provided the full data. I knew a structural engineer personally who requested this data and they told him he'd have to pay something ridiculous like $125,000 for NIST to process his request and print the pages off. And this is data that in a real, professional report would have already been published.