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Politics : View from the Center and Left -- Ignore unavailable to you. Want to Upgrade?

To: epicure who wrote (253138)	6/17/2014 1:50:25 PM
From: Alex MG	Read Replies (1) \| Respond to of 541759

but there's really nothing to debate... one could debate whether Bush & Co looked the other way and let it happen, but really they were just incompetent jerks... but what took down the towers is not really scientifically debatable architecture.about.com "...Jet fuel burns at 800° to 1500° F. This is not hot enough to melt structural steel. However, engineers say that for the World Trade Center towers to collapse, their steel frames didn't need to melt, they just had to lose some of their structural strength. Steel will lose about half its strength at 1,200° F. The steel will also become distorted when heat is not a uniform temperature. Videos of both buildings showed inward bowing of perimeter columns resulting from a sagging of heated trusses on many floors. ... The Twin Towers were built in the 1970s. No building constructed at that time would have been able to withstand the impact of the terrorist attacks in 2001. We can, however, learn from the collapse of the towers and take steps to construct safer buildings and minimize the number of casualties in the event of a disaster. When the Twin Towers were constructed, the builders were granted some exemptions from New York's building codes. The exemptions allowed the builders to use lightweight materials so the skyscrapers could achieve greater heights. But, the consequences were devastating. According to Charles Harris, author of Engineering Ethics: Concepts and Cases, fewer people would have died on September 11, 2001 if the Twin Towers had used the type of fireproofing required by older building codes. A tragic legacy of September 11 is that new construction in the USA must now adhere to more demanding building codes. Tall office buildings are required to have more durable fireproofing, an extra emergency exit, and many other safety features. To learn about the new building codes and their impact on architectural design, see: Did 9/11 Change the Way We Build? Some people believe that the Twin Towers were brought down by explosives. Researchers have shown "the allegations of controlled demolition to be absurd" and that the Towers "failed due to gravity-driven progressive collapse triggered by the effects of fire." Nevertheless, conspiracy theories continue.