Deconstructing the Deconsructionists, Part II

Anyway, where were we? Oh, yeah, right, the idiot 9/11 conspiracy claims . . .

B-25s and 767s, and why the Empire State Building didn't collapse and the WTC towers did. Let's see. The Empire State Building, constructed of steel girder "boxes," reinforced concrete columns and a thick, masonry exterior, has a structural density of 38 pounds per cubic foot. The WTC towers, constructed of an interior core of steel and concrete - where the elevator shafts and stairwells were located - an exterior skin of 14" box columns fabricated from steel plate, and tied together by the floor trusses and a "hat truss" on the roof that tied the exerior skin and the central core together, had a structural density of eight pounds per cubic foot. Which is, by the way, less than the density of balsa wood, at ten pounds per cubic foot.

Do the math, kiddies. A B-25, which at maximum load weighed 41,800 pounds, traveling at 200 miles per hour and striking a building with a density of 38 pounds per cubic foot, isn't going to do the same kind of damage as a 767 weighing 395,000 pounds at full load, traveling between 450 and 500 miles an hour and striking a building with a density of eight pounds per square foot.

The truth is, no modern skyscraper would have survived an impact such as the one the WTC towers experienced. Not only would any contemporary skyscraper have collapsed, it most likely would have done so immediately. The wonder isn't that the towers collapsed, its that they lasted as long as they did.

Cl.. The planes simply caused too much damage to the towers when they hit. After all, the buildings had been designed to withstand the impact of a jetliner. The aircraft that hit the North Tower impacted in the area of the 93rd to 99th floors. The one that hit the south tower did so in the area of the 77th to 85th floors. Yet those impacts and the fires subsequently disrupted elevator service and caused damage to the lobbies of both buildings. Given the distances involved, there is just no way such widespread damage could have been caused by those impacts unless other explosive devices, previously planted in the buildings, had been detonated simultaneously.

It's really a pity that we apparently don't teach simple physics in this country any more. You see, there's this thing that scientists like to call "gravity," and . . .

The damage patterns caused by the impacts really shouldn't come as a surprise to anyone. The debris caused by those impacts - the wreckage of the aircraft themselves and everything generated by them hitting the buildings - would have and did continue in the direction those planes were moving. At the same time, gravity would have been pulling all that debris down and, when the debris encountered something that would have allowed it to do so, it would head for the ground.

The debris, including the fuel loads of the aircraft which by this point would have been on fire, continued through the towers and cut the stairwells, elevator shafts, air shafts and utility shafts in the central cores. The burning jet fuel, and even some of the debris, would thus have an unimpeded means of reaching the lower floors of the towers, which is exactly what happened. Especially in regard to the fuel, those shafts acted as funnels, and the liquid did what liquids do when they are flowing: it sought the path of least resistance.

The same phenomenon occured in 1945 when the B-25 hit the Empire State Building. The aircraft's fuel load sprayed into the building, and some of it flowed down the elevator shafts, causing fires in the lobby. So in 1945, so in 2001, and why would it be any different?

Ah, but the conspiracy theororists, on this claim, point to their ace in the hole. The testimony of an NYFD firefighter who, they like to quote, said that "We think there was [sic] bombs set in the building." The problem with that is, as that firefighter is the first to point out, that isn't what he said. What he did say, describing the impacts, was that "It sounded like a bomb."

Cl.. This one, actually, is one of my favourites, and another reason why I lament the fact that we don't seem to teach physics in this country any more. The claim is that the fires caused by the impacts of the airliners were not sufficient to cause the collapse of the towers. Unless you are using a blast furnace, you simply can not generate enough heat in a fire to melt steel and thus cause structural failure. The theororists point to the fact that no modern, fire-protected steel frame building has ever collapsed solely due to fire. The argument is that since that is impossible, demolition charges had to have been used in order to melt the steel and bring the buildings down.

Except that it doesn't work that way . . . Jet fuel burns at a temperature somewhere between 2,012 and 2,190 degrees Fahrenheit, which is admittedly less than the 2,750 degrees F needed to melt steel. The thing is, you don't have to melt steel in order for its structural integrity to fail, you just have to heat it for a long enough period of time. As an example, take a knife and try to snap the blade. That's a very difficult thing to do. Now, take that same knife, fire up your barbeque, and stick the knife into the fire for a while. When you then try to snap the blade, you'll find that it's pretty easy to do. Why? Because you've removed the temper of the steel and softened it.

The exact same phenomenon happened in the WTC towers. When the planes hit, many of the exterior load-bearing columns on the impact face were cut, as well as the associated floor trusses and the load-bearing columns in the central core. Those loads then had to shift to the surviving structural components. And, while it is true that those components were "fire-proofed," that insulating foam certainly didn't survive the impacts. A spray-on foam dating from the 1960s, there were known issues with that fireproofing material. A lightweight, fluffy material, it was known to crumble if touched, and there were many areas in the towers where, over the years, it had flaked off simply due to age. Prior to 9/11, there was an effort underway to replace that foam in the areas where it was missing.

Under the impact of the airliners, most of that fireproofing material would have been stripped away from both the severed structural components and the surviving components by the shock and the debris, leaving those components vulnerable to fire. In addition, surviving pockets of the material would have acted as heat sinks, which is, after all, the function of fireproofing. That would have functioned to transfer even more heat to an already compromised structural member.

Moreover, after the impacts, it wasn't just the fuel from the aircraft that was burning. Everything else that was combustible was burning, too: fixtures, furniture, carpeting, papers, desks, plastics . . . The jet fuel was merely the ignition source, and would have burned off within the first ten minutes or so. But the fires the fuel ignited would have kept burning until they ran out of air or of combustion sources.

The NIST estimates that the fires in the towers, after the jet fuel burned off, were burning at an average temperature of 1,832 degrees Fahrenheit. Steel begins to lose its structural integrity at about 750 degrees F and, at temperatures of about 1,100 degrees F, loses roughly 50% of its integrity. At about 1,800 degrees F, steel retains only about 10% of its structural integrity.

Again, do the math, kiddies. A normal building fire radiates out from its ignition point, consuming flammables as it goes. By the time it spreads to more distant parts of the building, the combustibles at that ignition point have been largely consumed, and temperatures drop as the fire there begins to die out. But the fires in the towers involved multiple floors, with the burning jet fuel igniting everything it came into contact with. Those kind of fires are known as conflagrations, and they spread rapidly from their origin points.

Those fires were also, by and large, confined within the towers, allowing them to generate even more heat, since there was nowhere for that heat to go. The severed structural connections would have transferred their loads to the surviving connections which, exposed to the prolonged, intense heat, would have begun to soften. When those connections then reached the point where they failed, they in turn would have transferred their loads to the next surviving connections, and so on. As the steel of the core columns softened and failed, they would have transferred their loads to the surviving exterior columns, through the floor and hat trusses. At the same time, those floor trusses, as they softened and failed, would have caused the floors to sag and pull the surviving exterior columns inward as they transferred their loads. When enough of those structural members lost their integrity, the buildings collapsed. And, yes, it's as simple as that.

In a sense, though, the conspiracy theororists are right. Fire alone did not bring down the towers. It is entirely possible that if they had merely suffered from fire, they would not have collapsed. But they didn't just suffer from fire, they suffered from impacts that severed many of the connections that gave the buildings their integrity, and the resulting load transfers from the impacts, combined with the load transfers induced by the fires compromising the steel's structural integrity, were more than the buildings could bear. At that point, gravity took over.

One more thing, in regard to the "demolition charges." Those things don't work by melting steel, either. A demolition charge goes off with a velocity of approximately 28,000 feet per second, much too fast to melt steel. It cuts the steel using brute force.

Cl.. This one, too, is related to the idea that demolition charges were used to bring down the WTC towers. As the buildings came down, clearly visible "puffs" of dust and other material were seen being ejected from the sides of the towers, below the "collapse shroud" itself. The argument is that those clouds of dust and debris could only have been produced by demolition charges.

Once again, however, our old nemesis physics rears its ugly head. The towers collapsed because the surviving structural components in the damage zones could no longer support those loads, or the loads of the floor above them. When the collapse initiated, the weight of everything above the highest undamaged floor below the impact zone came crashing down on that floor, causing it to immediately fail. The collapse then continued down to the next floor, and so on, in a cascading effect that moved faster with each failure. Structural engineers call this process "pancaking."

As each floor failed and collapsed under the wieghts bearing down on it, everything on that floor would have been compressed - including the air. And, just as the fuel from the airliners had done earlier, the resulting "shock wave" of compressed material would have sought the path of least resistance out of the building. Through the windows, through the stairwells, and through the elevator, air and utility shafts. Wherever it could find a way out of the building, it would have done so, at the weakest points it could find. If you had a perfectly sealed building, it is entirely possible that a collapse could initiate on the top floor, and expell a cloud of dust and debris from the bottom floor.

Furthermore, in a controlled demolition using explosive charges, you don't plant those charges high up in the building. The whole idea is to use the potential energy stored in the building to do most of the demolition work, so you plant the charges on the first floor and, if there is one, the basement. You take out the key structural members as low down as possible, and let the weight of the building do the rest.

The conspiracy theororist love to state that the collapse of the WTC towers "bear all the classic signs of a controlled demolition." And that statement is utter nonsense. First of all, since and intentional and an unintentional collapse both depend on removing the key structural members holding the building up, it is impossible to visually tell the difference between the two. Second, if you look at a building that is brought down by demolition charges, the collapse is always initiated on the ground floor. On the other hand, if you look at the collapse of the towers, you will see that it is initiated on the floors where the aircraft hit.

Finally, the technology to initiate the kind if controlled demolition that the conspiracy theororists insist happened to the towers simply does not exist. It is impossible to either configure the charges needed, or wire them, to get the desired result. Each charge would weigh thousands of pounds apiece, and you would need forklifts to move them. Moreover, in order to achieve the desired result, those charges would have to go off simultaneously in widely separated parts of 110-story buildings; but, no matter how you wired them, you could never achieve that simultanaity.

Cl.. Approximately eight hours after the WTC towers collapsed, the 47-story WTC 7 building also collapsed. WTC 7, in addition to housing New York City's emergency response office, also housed offices belonging to the CIA and the Secret Service. Therefore, since sinister, outside forces were directly behind 9/11, that building also had to be destroyed, because that is where the evidence of the conspiracy was to be found. Once again, the theororists point to a "controlled demolition" being responsible for the collapse.

And, once again, they are not just wrong, but blindly wrong. They proceed from the assumption that WTC 7, other than fire, was not otherwise damaged, and that is simply not the case. The building was, in fact, compromised severely, first by falling debris generated by the impact of the aircraft on the North Tower, and then by the debris generated later by the collapse of the tower. Contrary to the claims, photographs and eyewitness testimony exist confirming widespread damage to the roof, southwest corner, and upper stories of the south fact of WTC 7. That damage, combined with the large fires that had been burning unchecked in the building for almost eight hours, led to another case of progressive collapse as the structure lost its integrity. Again, this should not surprise anyone who has a basic understanding of physics. As a damaged support fails, it transfers its load to another damaged support, which will then fail as a result; once there are enough structural failures, the load-bearing capacities of undamaged supports will be exceeded, and they will then fail. Once more, gravity then takes over.

But the conspiracy theororists make much hay out of the "Pull it" comment attributed to Larry Silverstein, who leased WTC 7 from the NY/NJ Port Authority. They assert that "pull it" is the phrase used to initiate a controlled demolition.

The problem being that, according to those people who actually use demolitions to bring down buildings for a living all say that is not the case. No one in that business, it seems, uses the words "pull it" to initiate the demolition. Moreover, Silverstein himself says that what he was talking about was pulling out the firefighters who were in WTC 7 trying to control the fires. According to him, the NYFD had informed him it was a lost cause, and his "pull it" comment was an agreement to withdraw those firefighters. But, as they say, if you're going to jump to a conclusion, make it an extreme one.

The final nail in the controlled demolition theory is that there have been plenty of investigators, not connected to the Government, who have examined the debris from the World Trade Centre. Not one of them has ever found any evidence that demolition charges were used.

The reality of the situation is that not everything is consumed in a controlled demolition. Explosive residue remains behind on the structural members cut by the charges. Some of the wiring and primacord used to set the explosives off remains. And yet, no one has ever found any of that in the debris. Nothing. Unless, of course, we are to believe that everyone who has examined the debris is also in on the conspiracy . . .

Next time: the Pentagon.