February 17, 2005
The fact that a Spanish skyscraper is still standing after an intense fire consumed the steel and concrete tower for 24 hours provides real world evidence that fire alone does not cause high-rise towers to collapse. As an intense fire consumed the 32-story Windsor Building in Madrid’s business district, press reports began with the words “fear of collapse.” After 24 hours, however, the tower, which is a similar construction to the twin towers of the World Trade Center, remains standing.
The fact that an extremely severe fire did not cause the Spanish steel and concrete tower to collapse raises serious questions about the events of 9-11 and how they have been explained. Why did the Windsor Building remain standing when similar towers in New York City collapsed completely after being affected by much less intense fires burning for considerably shorter periods of time?
The Federal Emergency Management Agency (FEMA) sponsored engineers to conduct the World Trade Center Building Performance Study (BPS) to examine how the buildings of the WTC responded to the airplane crashes and fires that allegedly caused the collapses of the twin towers and WTC 7, a 47-story office building on the next block.
“Prior to September 11, 2001, there was little, if any, record of fire-induced collapse of large fire-protected steel buildings,” the BPS says in the chapter about the mysterious collapse of WTC 7, the third tower to collapse on 9-11. WTC 7 was not hit by aircraft or large pieces of debris and had only sporadic fires. At about 5:25 p.m., WTC 7, owned by Larry Silverstein, collapsed in what appeared to be a controlled demolition. It would be more accurate to say that no steel framed high-rise, like WTC 7, has ever collapsed due to fire. There is no explanation for why the WTC 7 collapsed except for the fact that Silverstein told PBS that the decision was made to “pull it” and “we watched it come down.”
The fact that the Windsor Building is still standing is proof that fire alone does not cause properly constructed steel and concrete towers to collapse.
Dr. W. Gene Corley, Senior Vice President of Construction Technology Laboratories (CTL) of Skokie, Ill., was team leader of the engineers who wrote the BPS. CTL is a subsidiary of the Portland Cement Association and “provides structural and architectural engineering, testing, and materials technology services throughout the U.S. and internationally.” According to its website, “CTL’s expertise extends beyond cement and concrete, encompassing virtually all structural systems and construction materials.”
WACO, OKLAHOMA CITY, AND WTC
Corley served as expert adviser during the government’s investigation of the 1993 fatal fire at the Branch Davidian complex in Waco, Texas. In 1995, Corley led a Building Performance Assessment Team (BPAT) investigation of the bombing of the Murrah Federal Building in Oklahoma City. In September 2001, once again, Corley was selected to head the team to study building performance after the attack on New York’s World Trade Center.
In the executive summary of the WTC study, Corley wrote that secondary fires caused the twin towers to collapse: ”The heat produced by this burning jet fuel does not by itself appear to have been sufficient to initiate the structural collapses. However, as the burning jet fuel spread across several floors of the buildings, it ignited much of the buildings’ contents, causing simultaneous fires across several floors of both buildings,” Corley wrote. “Over a period of many minutes, this heat induced additional stresses into the damaged structural frames while simultaneously softening and weakening these frames. This additional loading and the resulting damage were sufficient to induce the collapse of both structures.”
In the section that deals with the collapse of the twin towers, the BPS says: “Because the aircraft impacts into the two buildings are not believed to have been sufficient to cause collapse without the ensuing fires, the obvious question is whether the fires alone, without the damage from the aircraft impact, would have been sufficient to cause such a collapse. It is impossible, without extensive modeling and other analysis, to make a credible prediction of how the buildings would have responded to an extremely severe fire in a situation where there was no prior structural damage.”
The Windsor Building fire in Madrid provides an excellent real-world model to show how the twin towers should have responded to “an extremely severe fire” alone. The Windsor Building has central support columns in its core section, which is similar to the construction of the twin towers. This central core is what supported the gravity load of the towers.
In the Windsor Building fire, the fire is thought to have started on the 21st floor late on Saturday night, Feb. 12. The upper floors were consumed by intense fire for at least 18 hours. The fire moved down the building and burned the entire structure. The fire is reported to have burned temperatures of at 800 degrees Celsius, or nearly 1,500 degrees Fahrenheit.
There was a partial collapse of parts of the top 10 floors as the trusses, which went from the core columns to the outside walls, appear to have failed. It is important to note, however, that the lower floors did not collapse and the core section is still standing with a construction crane on the roof.
The complete failure of the 47-central support columns in the twin towers of the WTC is one of the key outstanding questions about what caused their collapses. It would be expected that they should have remained standing even if some of the floor trusses failed. There is no explanation for what caused the huge box columns to fail.
Two of the contractors who removed the rubble told me that they had found molten steel in the 7th basement level when they reached the bedrock where the columns were based. There is no explanation for what caused such intense residual heat to be found at the base of the twin towers, although some experts have pointed to powerful explosives.
By press time, Dr. Corley had not responded to questions about the BPS findings and the questions raised by the Windsor Building fire. Corley’s assistant said that he had just gone to the airport and would not be returning to the office until Feb. 28.
The Windsor Building was built from 1973-1979 in an area of Madrid where commercial property was developed on land owned by Rio Tinto, the international mining giant. This is thought to be the reason why the Windsor Building carries the name of the British royal family. The WTC towers were completed in the early 1970’s. The Windsor Building housed the offices of Deloitte Touche Tohmatsu, a multinational financial services company, which occupied 20 floors of the tower.
The area where the Windsor Building stands is a mixed residential and commercial area known as the AZCA zone. Dubbed ‘Madrid’s Manhattan’, AZCA contains a cluster of modern skyscrapers. The tallest one is the Torre Picasso, a 516-foot tower built in 1989. The Picasso Tower was designed by Minoru Yamasaki, who also designed the twin towers of the WTC. Union de Explosivos Rio Tinto, S.A., owns the land where the tower stands.
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