Fires in the 47-story office tower at the edge of the World Trade Center site undermined floor beams and critical structural columns, federal investigators concluded Thursday, as they attempted to curb still-rampant speculation that explosives or fuel fires were responsible for the building’s collapse of Sept. 11, 2001.The investigators said that if the city water main had not been broken during the collapse of the twin towers, the sprinkler system would likely have put out the fires at 7 World Trade Center, and the building would not have fallen.
The long-delayed report by engineers here at the National Institute of Standards and Technology in suburban Washington is intended to solve one of still lingering central questions about the 2001 attacks: Why did 7 World Trade Center fall, if it was not hit by an airplane.
“Heating of floor beams and girders caused a critical support column to fail,” said Shyam Sunder, the lead investigator. “Video and photographic evidence combined with detailed computer simulations show that neither explosives nor fuel oils played a role in the collapse that brought the building down.”
Dr. Sunder said the investigation pointed to how expansion that can occur in steel as it heats up in a fire needs to be considered to prevent skyscraper collapses.
“Our take-home message today is the reason for the collapse of World Trade Center 7 is no longer a mystery,” Dr. Sunder said. “It did not collapse from explosives or fuel oil fires.”
No one died when 7 World Trade Center fell, nearly seven hours after the twin towers came down. But the collapse of the adjacent tower — once home to branch offices of the Central Intelligence Agency, the Secret Service and to the Giuliani administration’s emergency operations center — is cited in hundreds of books and Internet sites as perhaps the most compelling evidence that an insider secretly planted explosives, intentionally destroying the tower.
It is the first skyscraper in modern times to collapse primarily as a result of a fire.
Mainstream engineers and government officials have rejected the speculation as ridiculous. But national polls have shown that perhaps as many as 1 in 7 Americans believe that the destruction of the World Trade Center towers was an inside job.
The investigators determined that debris from the falling twin towers ignited fires on at least 10 floors at 7 World Trade Center, which was about 400 feet north of where the city’s two tallest buildings once stood.
The blazes burned out of control for six hours, as the city fire department, devastated by the collapse of the twin towers, abandoned its efforts to extinguish the fire, and the sprinkler system was incapacitated.
The heat from these fires, the investigators said, caused the beams on the lower floors of the east side of the tower to expand, ultimately causing a girder on the 13th floor to disconnect from a critical interior column that supported the building’s long floor spans. Once the 13th floor gave way, a cascade of floor failures started down to the fifth floor, leading to the overall collapse of the tower.
Skeptics have questioned if explosives were planted at 7 World Trade Center, as well as the twin towers and the Pentagon, as the Bush administration was seeking a justification to invade Iraq and Afghanistan. What started as a small number of such conspiracy theorists has only ballooned into a movement of sorts, largely fed by Internet sites that promote the theories.
“Seven World Trade Center is one of the key points of evidence, one of the smoking guns,” said Richard Gage, a California architect who leader a group called Architects and Engineers for 9/11 Truth. “There have been much hotter, longer lasting and larger fires in skyscrapers that have not fallen down.”
The engineers also examined whether diesel fuel tanks in the building — to power the Giuliani administration’s emergency operations center and other government offices — might have been an addotional fuel source that caused the collapse.
Allan W Janssen is the author of the book The Plain Truth About God (What the mainstream religions don't want you to know!) and is available as an E-Book H E R E ! and as a paperback H E R E !
Visit the blog "Perspective" at http://allans-perspective.blogspot.com
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