Posted on 09/11/2001 4:27:20 PM PDT by Looking for Diogenes
Sept. 11, 2001 |
The World Trade Center's twin towers were the tallest buildings in the world at the time of their opening in 1970. They each stood 110 stories and more than 1,300 feet tall. They are the dominant features in an enormous office complex totaling more than 9 million square feet of office space and together make up one of the most recognizable architectural landmarks in the world.
Today they were reduced to heaps of rubble after one of the worst catastrophes in U.S. history. A pair of jetliners crashed into them Tuesday morning -- at precisely the points at which they would do the most damage, according to architectural experts. The impacts created fires and, ultimately, brought about the collapse of both buildings.
Why did the buildings collapse?
According to Gregory Fenves, a professor of Civil Engineering at the University of California at Berkeley, the planes weakened the buildings' structures at key points. Fenves, working on information gleaned from preliminary TV reports, stressed that he was speculating. He said that if the planes had hit the structures higher, they could have merely damaged their tops; if they had hit lower, they would have been up against the enormous weight and resistance of the base of the buildings.
The buildings were architecturally interesting in many ways. Each structure is based on a central steel core, which is surrounded by the outside wall, a 209-foot by 209-foot cube of 18-inch tubular steel columns, set 22 inches apart. The cores and "tube walls" share the enormous physical weight of the structures and protect them against the extraordinary wind forces of buildings that tall. There are trusses that support each floor, but no other columns between the cores and outside walls. Some floors contain nearly 40,000 square feet of open office space.
News reports said the planes were jetliners, a 757 and a 767. The 757 has a 124-foot wingspan, is 155 feet long and can weigh 100 tons. A 767 is bigger, with a 156-foot wingspan and 159-foot length and can weigh a maximum of 200 tons. (A 747 is more than 200 feet long and can weigh 400 tons.)
The planes hit the buildings near the 70th or 80th floors. Their impact severely damaged the tube walls, which carried a large proportion of the buildings' weight. CNN footage of the second plane hitting a tower appeared to show that a large part of the jetliner went all the way through the building, suggesting that the interior core was also damaged.
Once a building like a World Trade Center tower loses some of its support, the building in effect goes to work, Fenves said. "The loads are trying to redistribute," he said. "The loads are figuring out how to get back down to the ground." At the same time, he noted, the fires are deforming the physical properties of the support steel.
"It's a very rugged system," he said. "It takes a long time for the collapse mechanism to develop. It's not like kicking the leg out from underneath a chair. The building is 200-foot square and there's a lot of structural system there."
But once the upper floors began to give way, terrible force was set in motion. Each floor of a building that big might weigh 6 million pounds, he said. Once impact is factored in as well, he said, the force becomes irresistible.
The disaster is a terrible echo of another disaster involving a New York landmark.
On July 25, 1945, a B-25 bomber slammed into the north side of the Empire State Building, then the tallest building in the world. A reckless pilot was flying over Manhattan in poor visibility; it was apparently an accident. Thirteen people died, mostly in fires started by burning gasoline.
The Empire State Building, Fenves noted, was built during the Depression, and made with a much heavier structural system. The bomber in that accident was also a much smaller plane, said Fenves.
The WTC buildings' official names are One and Two World Trade Center; their respective heights are 1,368 and 1,362 feet tall. They are part of a massive seven-building complex near the southeastern end of Manhattan. The center's architect was Minoru Yamasaki. The engineers were John Skilling and Leslie Robertson of Worthington, Skilling, Helle and Jackson.
The complex cost $350 million in 1966, or nearly $2 billion in today's dollars. Ground was broken in 1966, and the buildings opened in 1970, but the complete center was not finished until 1974; there are now seven total buildings, a large shopping mall, and an enormous garage. An observation deck is a popular tourist destination. Beneath the center two New York subway lines converge; there is also the Manhattan terminus of PATH commuter trains from New Jersey.
The center has been the target of an attack before. On Feb. 26, 1993, terrorists linked to Osama bin Laden planned and carried out a truck bombing in the parking garage. Prosecutors said the weapon was a 1,200-pound truck bomb. Six people died and more than 1,000 were injured in the attack. The explosion created a five-story crater beneath the building, but its structure held.
After the center opened in 1970, for several years it was feared the complex would become a real-estate white elephant. But for decades it then reigned as one of New York City's premier office buildings. A recent press release from the New York and New Jersey Port Authorities, which own the building, says that more than 430 companies from 28 countries are tenants. The authorities said that 40,000 employees work in the buildings daily, besides 140,000 daily visitors.
The World Trade Center lost its position as the world's tallest building in 1974, when the Sears Tower in Chicago opened. In 1998 the two Petronas Towers in Kuala Lumpur, Malaysia, opened; they are each more than 100 feet taller than the World Trade Center structures.
I agree with you. I don't believe that they had figured out how to make the buildings implode. More likely they followed the law of "gross tonnage"--accellerate a big plane loaded with fuel towards the target. If they hit, they could count on Palestinian dancing in the street.
That there was some sophistication is evidenced by turning off the radars, etc, and (possisbly) flying low enough in DC to go off the radars.
The fact that four planes were used is mere audacity. No one could have expected that. By staying as low tech as possible and looking for huge symbols and destruction, they may feel that their terrorism was effective. It is because we have lived in freedom that much of this was possible. We will remain free, but today means the books are being rewritten. We need to recah to our religious roots in order to find the resolve and strength needed in these times.
"Palestinian" is a made up word anyway, it comes from the "Philistines."
I feel bad for them, I'd personally rather they make their state in Jordan.
They dance in the streets because of the lies they are taught, the hatred they are raised with. I'd rather help them than waste them. It's the leadership I want to crush. Anyone, ANY world leader who supports ANY terrorism--not just this specific group--should be extreminated, unless he delivers up the heads of all of the terrorists living in his country.
Hitting the building is the easy part, assuming you are lined up.
The line up. Hitting a building is like a bombing run. You need to make a turn to the final run-in course and not overshoot.
Speed. The second plane was clean (flaps and gear up), which means it was travelling over 200 knots (probably more like 300). Flying at that speed and hitting the target requires more skill.
The planes took off out of Boston, and were travelling to California. Depending on when they were taken over, they had to be flown for some time, descended from a high altitude, etc.
Interestingly, the planes were modern (757, 767). These new planes have sophisticated navigation systems, with multiple inertial systems updated by GPS. Very accurate. Most older planes like the 727 don't have this. With GPS, and good coordinates of the target, it makes it easy.
A skilled private pilot, using a good PC flight simulator, could prepare for this, to include learing how to operate the navigation system, but PC simulators don't provide the side vision needed to estimate when to make a turn to the run-in course. If an initial point was programmed into the naviation system, the terrorist could have used it to lead the turn to the run-in course.
In short, I doubt some slack-jawwed yokel from the streets of middle east did this. This is not driving a truck into a building.
*Very* astute.
I had come to the same conclusion myself.
People are assuming that the terrorists "knew exactly" how to bring down the buildings. They're forgetting these scenarios:
1. The terrorists naively and wrongly assumed that the plane impacts alone would topple the towers, but they didn't. But they got lucky and the flames finished the job, much to their surprise.
2. The terrorists figured the best they could do was to cause twin "towering inferno" out of control fires (which is why they made sure they used fully fueled planes, and hit high enough that water from the ground couldn't be sprayed on the fire), which would be more than enough to cause enormous death tolls and major financial/business disruption. They simply succeeded better than they dreamed when the fires caused the buildings to fail structurally.
Other factors which point to less than masterful planning was the relatively small amount of damage to the Pentagon (and into the *least* occupied wing of the building), and the botched fourth hijacking.
I don't see this as necessarily being the work of criminal masterminds. Balls and sheer luck could have been all that was needed.
Finally, it wouldn't surprise me if all the structural advice necessary to do even a planned demolition was contained in the pages of Time and Newsweek in the weeks after the original WTC bombings -- remember how all the news magazines fell all overthemselves interviewing building engineers and posting breathless stories about how, "it could have been worse, things could have been really catostrophic had the terrorists instead done something more like..."
Hey, turkey!! If I didn't live in an anti-RKBA state, I WOULD BE an 'average permit holder! So might you--so are you going to hijack a plane because your wife kicked you out of bed? Or because your "god" told you to kill Americans to get to heaven? You think you'd get a permit??
Another way to think of it is: how many crimes did permit-holders commit in the last, oh, say, century? Rarely do I call someone ignorant, but you get the first runner-up prize...
if there were explosives planted, why would they wait an hour to let the building occcupants flee.
a new report just came out that NYPD cops caught a truck full of explosives on the george Washington bridge over the hudson River.
When I was doing research for our terrorism response plan, one of the things I found out was that the bomb in the last World Trade Center bombing was actually strong enough to bring the building down, and the planners had it figured out fairly well. The problem was that the people who carried out the bombing put the vehicle in the wrong place.
The original plan was to take out the base of one corner of the "cube" that provided the infrastructure support. If the bomb had been parked in the right place, it would have collapsed one tower into the other.
I suspect that the reason the WTC has been targeted multiple times is because the terrorists believed the nature of the structure would allow a complete collapse under the right circumstances.
If there was indeed state support of this act (down to technical guidance, logistics, what have you), the US Government might be able to confiscate that nations financial assets that are deposited/invested through US institutions (that was done during the Tehran Embassy hostage crisis). Thus used for compensation. Question: would there have to be a Declaration of War, or other Act of Congress, in order to sieze assets in such a manner? (don't get into asset forfeiture in the War on Drugs, this is another matter)
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