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1 posted on 09/11/2001 8:12:00 PM PDT by SlickWillard
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To: SlickWillard

From the Chicago Tribune

Skyline symbols of economic might

Engineers shocked by towers’ collapse

By Blair Kamin
Tribune architecture critic

September 11, 2001, 12:18 PM CDT

The World Trade Center, a symbol of American economic might, survived one terrorist attack in 1993. It was designed to withstand the impact of a jet, but both its towers collapsed this morning after planes rammed them.

The structural engineer who designed the towers said as recently as last week that their steel columns could remain standing if they were hit by a 707.

Les Robertson, the Trade Center’s structural engineer, spoke last week at a conference on tall buildings in Frankfurt, Germany. He was asked during a question-and-answer session what he had done to protect the twin towers from terrorist attacks, according to Joseph Burns, a principal at the Chicago firm of Thornton-Thomasetti Engineers.

Burns, who was present, said that Robertson said of the center, “I designed it for a 707 to smash into it.”

Burns, whose firm did the structural engineering for the Petronas Twin Towers in Malaysia -- the world’s tallest buildings -- said Robertson did not elaborate on the remark. Robertson could not be reached early today.

Completed in 1972 and 1973, the 110-story twin towers were the fifth and sixth tallest buildings in the world. One World Trade Center, finished in 1972, was briefly after its construction the world’s tallest building. The towers have been called “a monumental gate to New York and the United States.”

They withstood the 1993 attack, when a bomb-laden van exploded, killing six people and injuring more than 1,000.

Closely spaced steel columns that ringed their perimeter held up the World Trade Center towers. Chicago’s Aon Center (formerly the Amoco Building), completed in 1973, uses a similar support system, known to structural engineers as a “tube.”

Shocked by the building’s collapse, structural engineers pointed to fire as the likely cause of the structural failure.

“Fire melts steel,” Burns said. In addition, he said, the impact of the plane could have severely damaged the building’s sprinklers, allowing the fire to rage, despite fireproofing supposed to protect steel columns and beams.

“You never know in an explosion like that whether they (the sprinklers) get cut off,” Burns said.

Architects Minoru Yamasaki and Associates, in association with Emery Roth & Sons, designed the World Trade Center.

The structural engineers were the firm of Skilling, Helle, Chrstiansen, Robertson. The developer was The Port Authority of New York and New Jersey.

Today’s attack marked the second time that a plane has crashed into a New York City skyscraper, although the first incident was an accident.

In 1945, a B-25 flying at 200 miles per hour slammed into the 78th and 79th floors of the Empire State Building, gouging an 18-by-20-foot hole 913 feet above the streets of Manhattan. The pilot, Lt. Col. William F. Smith Jr., had been heading from New York’s LaGuardia Airport to Newark, N.J., when he became disoriented.

Fourteen people died in the crash and the fire that followed -- three people in the plane and 11 in what was then the world’s tallest building.

Like the World Trade Center, the Pentagon, which also was struck by a plane, provided a sizable and symbolic target.

The Pentagon is the world’s largest office building, with a total of 6.5 million square feet, serves as headquarters for the world’s most powerful military. Sears Tower, by comparison, has about 3.5 million square feet of office space.

Copyright © 2001, Chicago Tribune

2 posted on 09/11/2001 8:15:39 PM PDT by SlickWillard
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To: SlickWillard
Lets see....half a million people huh?

That comes to 500,000 divided by 220 floors (110 stories each tower).

Thats 2300 people per floor? Nope...dont think so, not even when you count the ancillary buildings, such as the 47 story Tower 7 etc.

3 posted on 09/11/2001 8:20:05 PM PDT by keithtoo
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To: SlickWillard
The Jerusalem Post

WTC architect: Collapse 'unbelievable'

By Michal Meyer and Stuart Winer September, 12 2001

JERUSALEM (September 12) - Aaron Swirsky, one of the architects of the World Trade Center, yesterday expressed disbelief on hearing of the collapse of the twin towers. Swirsky told JPostRadio the buildings had been designed with "accidents" in mind.

"The terrorism was different in those days, but there was always the possibility of an accident with a plane hitting the building. The building was designed like a pipe structurally, with the main structure in the perimeter of the building." This meant that a hole in the building would not collapse the whole structure. The fact that the buildings did collapse he described as "incredible."

Swirsky said the 1993 bombing of the World Trade Center made a big hole in one building. "The intent was to topple the building, but because of the design it didn't. But now... it is unbelievable." He said the collapse may have been due to the size of the plane, bigger than the architects had ever planned for.

The floors above the crash sites would have been safe, at least at first, said Twirsky. "What is really tragic is the building was designed with each floor as a hermetic unit, as to evacuate a building like that is a nightmare. Imagine you are on the 100th floor and there is no elevator, so each floor is designed to be safe; but when it collapses then that whole theory goes up in smoke."

The buildings had no sprinklers, because each floor could be sealed off from the others in case of a fire. "There are shutters that would shut off the vertical openings [between floors] so that the fire couldn't travel from one floor to the other. That was the theory. When the danger had subsided they could evacuate."

After the planes crashed into the buildings, Swirsky said people in the floors above would have been trapped. They would have been unable to escape. The buildings were not designed to allow for a quick exit in case of emergency. Afterward, those trapped would have fallen with the buildings when they collapsed.

5 posted on 09/11/2001 8:22:31 PM PDT by SlickWillard
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To: SlickWillard




12 posted on 09/11/2001 8:39:59 PM PDT by dodger
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To: SlickWillard
First of all, that idiot is *not* the architect of the WTC. A japanese guy (died 1986) was, and he had 2 assistants, neither of whom was named "Swirski".

How can "one of the architects" of perhaps the most famous modern buildings in the world be off as to their occupation capacity by a factor of 10?

22 posted on 09/11/2001 9:15:41 PM PDT by BushMeister
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