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these writer and their sources what to say they are too stupid to make intelligent comments ======================================== The Washington Post September 12, 2001 Wednesday Final Edition 'Magnitude Beyond Anything We'd Seen Before'; Towers Built to Last But Unprepared For Such an Attack BYLINE: Guy Gugliotta, Washington Post Staff Writer SECTION: A SECTION; Pg. A18 LENGTH: 894 words Built to withstand earthquakes and hurricane-force winds, and equipped with enhanced security after a 1993 terrorist bombing, the twin towers of New York's World Trade Center were supposed to last. Their architect boasted that they could withstand the impact of a jumbo jet. But when two hijacked commercial jetliners crashed into the 110-story structures within 20 minutes of each other early yesterday morning, experts flinched, for "what we saw today was several orders of magnitude beyond anything we'd seen before," said the National Academy of Sciences' Richard Little, who has overseen several studies on how to protect buildings from terrorist attacks. "We were hopeful at first," said Pennsylvania State University architectural engineer Kevin Parfitt, who teaches a course in building failures. "But the longer the fire burned, the more we feared the outcome." With justification. In just under an hour, a raging fire from burning jet fuel softened or perhaps melted the steel strength members supporting 50 floors of undamaged skyscraper above the point of impact in the South Tower. The top floors slumped to the damaged area, and the impact of the dead weight caused the entire building to pancake to the ground. A half-hour later, the North Tower collapsed in the same way. By late afternoon, the 47-story Building 7, another of the center's seven buildings, had also fallen after burning all day. Building 6, the U.S. Customs House, was a smoldering, soot-blackened hulk. Experts agreed that collapse of the two towers was almost inevitable; although their "tube structure" design was their greatest source of strength, it was also an Achilles' heel. For someone who wanted to bring them down, a guided missile filled with jet fuel was perhaps the only way. The towers were built like "rectangular doughnuts," Parfitt said. Strength came from a central steel core and from steel columns spaced closely around the perimeter of each building. There was no structural support between the core and the outer walls. "When the planes come through, they cut through a number of those columns," Parfitt said. "At the same time, the planes are starting transcontinental flights, and they have full tanks of aviation fuel. You get a massive explosion and a fire."
The initial jet fuel explosions most likely blew the insulation off the towers' girders, Parfitt suggested, incinerated easy combustibles and gave the ensuing fires free access to the unguarded steel. "Sprinklers aren't going to do too much in that situation," Parfitt said.
For the people inside the buildings trying to escape, what followed was a macabre race against time, and the odds were not good. Each of the Trade Center towers had 250 elevators, but only three stairwells. Between 20,000 and 25,000 people had to get out of each building as rapidly as possible.
In 1993, after terrorists set off a bomb in a basement garage, it took four hours to evacuate the towers, but Dennis Wenger, director of the Texas A&M University Hazard Reduction and Recovery Center, said half the occupants got out in the first hour.
"There was no panic, and a lot of cooperation," even though the stairwells were "quite narrow" and smoke was wafting upward as people climbed down, said Wenger, who studied the 1993 evacuation.
In some ways, yesterday's scenario might have seemed better -- the fires were above most of the occupants. But what they didn't know was that -- in the South Tower -- they had less than an hour to get out. The North Tower was not much better.
The end came when the fire had softened the girders so that the weight above the crash sites became unsupportable. The South Tower, hit lower down, fell first beneath the greater weight. The North Tower, with less weight above the explosion, held out a bit longer: "The whole thing just imploded," said Melvyn Blum, 55, a real estate executive who was watching through a telescope from his 44th-floor office a few miles away on Manhattan's Seventh Avenue, "just like you see when they take buildings down with dynamite."
Angus Kress Gillespie, author of the 1999 book "Twin Towers: The Life of New York City's World Trade Center," said architect Minoru Yamasaki had designed the towers to withstand the impact of a jumbo jet, "but planes have become bigger" since the center was built in 1972. Minoru Yamasaki Associates (MYA) issued a statement yesterday saying the firm was in contact with authorities and had offered assistance. "We believe that any speculation regarding the specifics of these tragic events would be irresponsible," the statement said. "For obvious reasons, MYA has no further comment at this time."
By late Tuesday, few were criticizing Yamasaki for misplaced bravado. After the 1993 bombing, the center's towers "were probably among the half-dozen strongest buildings in the world, but it couldn't withstand that kind of insult," Little said.
Cesar Pelli, designer of the Petronas Towers in Kuala Lumpur, Malaysia, the world's tallest buildings, suggested that although "it will take structural engineers a long time to figure out exactly how" the towers collapsed, he agreed that "no building is prepared for this kind of stress.
"I feel a tremendous sense of loss, but this is insignificant when you think of the horror of the loss of life," Pelli said. "The grief is just unimaginable."
LOAD-DATE: September 12, 2001 LANGUAGE: ENGLISH PUBLICATION-TYPE: Newspaper Copyright 2001 The Washington Post
Sunday Express
September 16, 2001 32 - PAGE NEWS SPECIAL; WHY DID THE TOWERS CRUMPLE INTO DUST?
BYLINE: By Keith Perry SECTION: NEWS; Pg. 14 LENGTH: 875 words
STANDING proud on New York's skyline, the twin towers of the World Trade Center were built to withstand earthquakes, bomb attacks and hurricane force winds.
The buildings were fitted with enhanced security after the 1993 terrorist bombing and their architect boasted that they could withstand the full impact of a jumbo jet.
But when two hijacked airliners ploughed into the 110-storey buildings, building experts were appalled at the extent of the devastation. "What we saw today was several orders of magnitude beyond anything we had seen before, " said Richard Little of the National Academy of Sciences.
Mr Little is an expert on how to protect buildings from terrorist attacks. "We were hopeful at first, " said Kevin Parfitt, an architectural engineer at Pennsylvania State University who runs a course in building failures. "But the longer the fire burned, the more we feared the outcome."
In just under an hour, the raging inferno caused by burning aviation fuel melted the steel core structure supporting the 50 floors of undamaged skyscraper above the point of impact in the South Tower.
The top floors collapsed into the undamaged area and the impact caused the entire building to crumple to the ground. Just half an hour later the North Tower collapsed in the same way. By late afternoon, the 47-storey Building 7, another of the Center's seven buildings, had also collapsed after burning all day.
Building 6, the US Custom House, was reduced to a smouldering, blackened hulk.
Construction experts believe the collapse of the two structures was "almost inevitable". Although their "tube structure" design was their greatest source of strength, it was also a fatal weakness.
Someone who wanted to destroy the buildings would realise that using a fuel-laden commercial jet as a missile was probably the only way.
"The towers were built like rectangular doughnuts, " Mr Parfitt said. "Strength came from a central steel core and from steel columns spaced around the perimeter of the building. There was no structural support between the core and outer walls.
"When the planes came they cut through a number of those perimeter columns, " Mr Parfitt said. "At the same time, the planes are starting transcontinental flights and they are equipped with full tanks of aviation fuel. The result is a massive explosion and a fire.
"The initial jet fuel explosions probably blew the insulation off the towers' girders, " Mr Parfitt suggested. They also incinerated easy combustibles and gave the ensuing fires free access to the unguarded steel.
"Sprinklers aren't going to do much in that situation, " Mr Parfitt said. For the people inside the buildings trying to escape, what followed was a terrifying race against time in the face of impossible odds. Each of the Trade Center towers had 250 lifts but only three stairwells. Between 20,000 and 25,000 people had to get out of the building as rapidly as possible.
In 1993, after terrorists set off a bomb in a basement garage, it took four hours to evacuate the towers, but Dennis Wenger of the Texas A&M University Hazard Reduction and Recovery Centre, said half of the occupants got out in the first hour.
"There was no panic and a lot of co-operation, " even though the stairwells were quite narrow and "smoke was wafting upward as people climbed down, " said Mr Wenger, who studied the 1993 evacuation.
The scenario on Tuesday might have seemed better - the fires were above most of the occupants.
But what they didn't realise was that in the South Tower they had less than an hour to get out. The situation on the North Tower was not much better.
The tragic end came when the fire had softened the girders so much that the weight above the crash sites became unsupportable.
The South Tower, which was hit lower down, fell first beneath the greater weight.
The North Tower, with less weight above the explosion, held out a bit longer.
"The whole thing just imploded, " said Melvyn Blum, 55, an estate agent who was watching through a telescope from his 44th floor office a few miles away on Seventh Avenue in Manhattan.
Angus Kress Gillespie, the author of the book Twin Towers: The Life Of New York City's World Trade Center, said that the architect Minoru Yamasaki had designed the towers, which were built in 1972, to withstand the impact of a 747.
Minoru Yamasaki Associates issued a statement saying the firm was in contact with the authorities and had offered assistance following the tragedy. But it declined to comment on the devastation.
Few would criticise the architect for his original bravado. After the 1993 bombing, the towers were described as probably among the strongest half-a-dozen buildings in the world, but it "couldn't withstand that kind of insult", Mr Little said.
Cesar Pelli, designer of the Petronas Towers in Kuala Lumpur, Malaysia, the world's tallest buildings, suggested that "it will take structural engineers a long time to figure out exactly how the towers collapsed".
He added that no building was designed "to take this kind of stress".
"I feel a tremendous sense of loss, " Mr Pelli said, "but this is insignificant when you think of the horror of the loss of life."
LOAD-DATE: September 16, 2001 LANGUAGE: English PUB-TYPE: Newspaper Copyright 2001 EXPRESS NEWSPAPERS
The Ottawa Citizen
September 13, 2001 Thursday Final EDITION
Towering infernos: World Trade Centre designed to handle plane crashes, but not fire, expert says
BYLINE: Tom Spears SOURCE: The Ottawa Citizen SECTION: SPECIAL SECTION, Pg. B10 LENGTH: 731 words
The World Trade Center could have survived the impacts of two airplane crashes but fell because its steel pillars softened in the burning jet fuel, says a Boston professor of skyscraper design.
"The structure itself performed very well. After the impact, we saw the structure shook a little bit and it would have stood if there was no fire," said Masoud Sanayei, professor of civil and environmental engineering at Tufts University,
"There was intense heat -- more than ordinary fires that buildings experience because of the large amount of jet fuel." He wouldn't give an estimate, but said it would be thousands of Fahrenheit degrees.
"The fire was the cause of the actual collapse," he said.
The towers had what engineers call "tube-in-tube" construction.
One ring of steel columns stood around the building's outer edge, like a giant steel pipe standing on end. An inner cluster of columns stood like a second tube around the elevator shaft in the building's centre.
Across these columns were fastened reinforced concrete slabs that formed each floor.
"They are very strong in the vertical direction to carry the gravity load (i.e. the building's own weight), and very strong in carrying lateral (sideways) loads such as wind loads and earthquake loads," Mr. Sanayei said yesterday.
"When the airplane hit one of the towers, it punctured it. But if you have a pipe standing up and it has a hole in it, it still stands up. It is designed for that.
"Then the fire started.
"Steel softens as a result of high temperatures, and then it can't carry as much load."
Steel loses half its structural strength when its temperature reaches 500 to 600 degrees fahrenheit.
At most, given the massive fire, he believes such a skyscraper could only have stood for two or three hours. But no one could have predicted the exact moment when the buildings became too weak to stand.
As the steel was starting to soften, concrete slab floors expanded in the intense heat, and this probably caused them to break their connections with the steel supports.
"When one of these floors collapses, then it hits the one below" with a heavy force, he said.
"Then the next one (below is hit) and the next one, causing a domino effect," even in the bottom half of the building, which had suffered no damage in the initial crash or the fire.
"It implodes into itself."
Engineers call this form of collapse "pancaking," as each slab flattens itself on top of the one below, guided and contained by the steel columns. The same thing happens in the controlled demolition of an building, where it prevents debris from flying outward.
"It is very difficult for anyone to survive this pancaking. There is no space between the slabs."
Mr. Sanayei is a structural engineering expert specializing in skyscrapers and teaches a course called Skyscrapers: Architecture & Engineering.
Earthquakes and fires always lead to updates in building codes, and this one will likely lead to new rules for skyscrapers, especially dealing with fire resistance, he said. But the most important thing is to improve airport security.
He also calls for better ways of evacuating tall buildings.
Hyman Brown, a University of Colorado civil engineering professor and the construction manager for the World Trade Center, agreed that burning jet fuel melted steel columns.
"This building would have stood had a plane or a force caused by a plane smashed into it," he said.
"But steel melts, and 24,000 gallons of aviation fluid melted the steel.
"Nothing is designed or will be designed to withstand that fire."
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