<<<My interest in this thread started due to the stated reasons as to why the towers failed... I read the "evidence" in these sites and also have discussed (in the past, and now my renewed interest leads to new discussions), this evidence with engineers who I happen to have a direct relationship and I cannot find hard evidence that these conspiracy theories could hold water....>>>
Fair enough. I was going over the PBS site again recently, and while I'll go along with the idea it sounds convincing, when you really look at what's there, there's absolutely nothing to support the theories, and the theories don't match all the evidence. A few examples:
"A professor of materials engineering and engineering systems at the Massachusetts Institute of TechnologyEagar went on to write an influential paper in the journal of the Minerals, Metals, and Materials Society entitled "Why Did the World Trade Center Collapse? Science, Engineering, and Speculation" (JOM, December 2001). In this interview, Eagar explains the structural failure, what can be done within existing skyscrapers to improve safety, and what he believes the most likely terrorist targets of the future may be."
Eagar has NO background in terrorism, and any expert status he may have in other fields does not translate to the subject. Note that his paper is described as being "speculation". I'd also question how far his specialty goes toward making him any kind of expert witness on building failures. By all rights, an engineer specializing in demolitions would be the expert required to point out the areas which would have to fail to bring the building down.
"NOVA: The Twin Towers collapsed essentially straight down. Was there any chance they could have tipped over?
Eagar: It's really not possible in this case. In our normal experience, we deal with small things, say, a glass of water, that might tip over, and we don't realize how far something has to tip proportional to its base. The base of the World Trade Center was 208 feet on a side, and that means it would have had to have tipped at least 100 feet to one side in order to move its center of gravity from the center of the building out beyond its base. That would have been a tremendous amount of bending. In a building that is mostly air, as the World Trade Center was, there would have been buckling columns, and it would have come straight down before it ever tipped over.
Have you ever seen the demolition of buildings? They blow them up, and they implode. Well, I once asked demolition experts, "How do you get it to implode and not fall outward?" They said, "Oh, it's really how you time and place the explosives." I always accepted that answer, until the World Trade Center, when I thought about it myself. And that's not the correct answer. The correct answer is, there's no other way for them to go but down. They're too big. With anything that massive -- each of the World Trade Center towers weighed half a million tons -- there's nothing that can exert a big enough force to push it sideways."
You will note he admits the experts say explosives have to be carefully placed to keep a building from falling sideways. He offers no evidence to support his theory that the experts don't know what they're talking about, other than his own experience knocking over glasses of water.
"Each floor was about an acre, and the fire covered the whole floor within a few seconds. Ordinarily, it would take a lot longer. If, say, I have an acre of property, and I start a brushfire in one corner, it might take an hour, even with a good wind, to go from one corner and start burning the other corner."
We know this is not true. There were survivors from the impact floors who could not possibly have lived if the entire floor was covered with fire in a few seconds. It is also unlikely an entire floor was open space without partitions for offices, storage, whatever. He's flat out making that part up as he goes along.
"This was a very unusual situation, in which someone dumped 10,000 gallons of jet fuel in an instant."
More of this later. In the mean time he offers no evidence to support the "10,000 gallon" figure. He just plain made it up.
"NOVA: How high did the temperatures get, and what did that do to the steel columns?
Eagar: The maximum temperature would have been 1,600°F or 1,700°F. It's impossible to generate temperatures much above that in most cases with just normal fuel, in pure air. In fact, I think the World Trade Center fire was probably only 1,200°F or 1,300°F.
Investigations of fires in other buildings with steel have shown that fires don't usually even melt the aluminum, which melts around 1,200°F. Most fires don't get above 900°F to 1,100°F. The World Trade Center fire did melt some of the aluminum in the aircraft and hence it probably got to 1,300°F or 1,400°F. But that's all it would have taken to trigger the collapse, according to my analysis."
Here he admits most fires don't get above 900. Tons of photos and videos show the thick black smoke pouring out of the towers that is typical of an oxygen starved condition, or a low temperature fire. In addition, there are plenty of photos showing only small fires burning through the holes in the building, which is nothing like the raging 1 acre inferno he invented.
It's worth mentioning that thermite is iron oxide and aluminum, and when it burns down, all that's left is the aluminum. Thermite reaches temperatures in excess of 3500 and is often used to cut (melt), or weld steel. So, here we have a fire that should not have reached 900, but there is melted aluminum, and not only is there melted aluminum, but melted steel as well. Kerosene (jet fuel) burns at around 800. Mr. Wizard offers no evidence, or even speculation, on how the temperatures reached the levels they did, when those temperatures should have been impossible under the conditions described.
"NOVA: You've pointed out that structural steel loses about half its strength at 1,200°F, yet even a 50 percent loss of strength is insufficient, by itself, to explain the collapse.
Eagar: Well, normally the biggest load on this building was the wind load, trying to push it sideways and make it vibrate like a flag in the breeze. The World Trade Center building was designed to withstand a hurricane of about 140 miles an hour, but September 11th wasn't a windy day, so the major loads it was designed for were not on it at the time.
As a result, the World Trade Center, at the time each airplane hit it, was only loaded to about 20 percent of its capacity. That means it had to lose five times its capacity either due to temperature or buckling -- the temperature weakening the steel, the buckling changing the strength of a member because it's bent rather than straight. You can't explain the collapse just in terms of temperature, and you can't explain it just in terms of buckling. It was a combination."
Here our boy starts getting just plain silly. The biggest load is always gravity. Then we get to the part where a 50% loss of strength isn't enough to cause buckling, but buckling and temperature caused the collapse.
"There are different levels of analysis. You can do the back-of-the-envelope, which was what I and other people did early on. But to do the full analysis will take much longer. I suspect there will still be people worrying about this ten years from now."
In other words, his "analysis" is not an analysis at all. I could keep going on just about every claim he made, but this is getting kind of long and I wanted to touch on a couple more key points. In the "letters" section of the site, Mr. Wizard makes this comment:
"Nevertheless, let me note that it would be impossible for all the fuel to burn within a few moments. Oxygen is required to burn fuel. If a liquid is vaporized -- as it must be in order for the oxygen to mix with the fuel and for combustion to occur -- the vapor occupies about 500 times the volume of the liquid. Thus, if the jet fuel was consumed mostly in the first few moments, three things must be present. First, there would have been a fireball of fuel 500 times as large as the liquid fuel multiplied by 5 times as much air as the oxygen required (because air is only 20 percent oxygen) or a fireball 2,500 times the volume of the liquid fuel that was consumed. While there was a fireball, it was not anywhere near this large. Second, there would need to be a source of the heat of vaporization to vaporize the fuel. This is what limits the rate of burning of most liquids, i.e., the heat necessary to vaporize the unburnt fuel. Third, the heat generated by this rapid burning would have to go someplace."
Using Mr. Wizard's make believe figure of 10,000 gallons, at 7.5 gallons per cubic foot, the volume of the fuel was 1,333 cubic feet. Using Mr. Wizard's figure of a multiple of 2,500 for the volume of the fireball, the fireball would have to have been 3.3 million cubic feet to consume 10,000 gallons of fuel. Sounds huge, yes? Digging up the formula for a sphere, the volume is three fourths pi, times the radius cubed. Since we know the volume, we can use simple high school algebra to find the radius which is 92 feet, or a fireball with a diameter of 184 feet. The towers were a little over 200 feet on a side, so we can use photos of the building and the fireballs, to get an idea how big the fireballs were.
Since Mr. Wizard has proven to be an unreliable source of information, there's probably no good reason to trust his math here, but if we use his numbers, the fireballs, which were approximately 300 feet across (though not perfectly round, and there was one on each side of the building) accounted for virtually all of the fuel on impact.
The last point I'd like to make is related to the "computer simulations" on the PBS site. As easy as it is to forget the fact, computers DO NOT "think". They can do math a lot faster than we can, but unless you put the correct information in, you will not get correct information out. It is not possible to get a "new" answer. You can make a yellow dot with eyes, that eats people while running through a maze, but that doesn't mean there is any relationship between that dot and the real world. |
