BRITISH AND US skyscraper experts this week clashed over the ability of megatowers to survive aircraft impacts similar to those that struck the World Trade Center on 11 September.
United States Council on Tall Buildings & Urban Habitat (CTBUH) chairman Ron Klemencic claimed it was 'not practical to design any building to withstand the maliciously directed impact of a large fuelladen aircraft'.
He told delegates at a London conference that this was the conclusion of the taskforce set up by the council in the wake of the 11 September disaster.
But Arup chairman Bob Emmerson disagreed and showed delegates computer simulations of aircraft damage to tall buildings which he said proved that some types of structure could survive such impacts.
But Klemencic said that, according to the CTBUH taskforce, WTC towers were among the few buildings in the world that would not have collapsed immediately under the impact of the Boeing 767s that struck them.
'Two unique features allowed the towers to stand long enough to allow 25,000 people to escape, ' he said.
'These were the enormous size of the floor plate - nearly twice as large as the typical tall building - and the perimeter tube construction which had lots of redundancy. But if it had been a 747 which had hit, the structure would have collapsed immediately.'
However, Arup's simulations of the effects of the impact of a typical 4t jet engine travelling at more than 300km/hr, suggested that very large composite 'megacolumns' could absorb such impacts without failing. Arup simulated an engine impact as the most solid and potentially damaging part of an aircraft.
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