14.09.2001:
Pressemelding fra NCSEA (National Council of Structural Engineers Associations)
Structural Engineers Offer Insight On World Trade Center Collapse
According to one of the designers of the World Trade Center
(WTC), the towers were originally designed to take the impact of a Boeing 707; and the
impact of the aircraft this morning did not take the buildings down. In
fact, WTC One stood for 1 hour and WTC Two stood for 1 3/4 hours after
impact. Engineers familiar with the chain of events suspect that heat from
the massive and extraordinary fires weakened the structures and initiated
the progressive collapses.
John Hooper, a structural engineer from Skilling, Ward,
Magnusson, Barkshire, the structural engineering firm that evolved from Skilling,
Helle, Christianson, Robertson, which was the structural engineering firm of
record for the WTC, provided the following facts to NCSEA: WTC One was 1368' tall, and WTC Two was 1362' tall. Each 110-story tower had a floor plate
that was 208' by 208'. The central core of each was 86' square. Around the
perimeter of the buildings, columns were spaced at 3'-3" on center, with
48"- deep plate girders at each floor. At the third level, the columns
transitioned in an arch-like formation to a 10'-0" spacing for the lower
story. Floors were supported by steel trusses spanning 60', from the core
to the perimeter wall, on each side of the building. The buildings are also
thought to have been the first buildings to use non-asbestos
fireproofing. The fibers of the spray-on fireproofing product were reportedly ceramic
rather than asbestos.
NCSEA has contacted FEMA and will coordinate and make available
structural engineers in the New York and Washington D.C. areas. NCSEA will also
coordinate and provide the services of Member Structural Engineering Associations throughout the U.S., as needed.
The National Council of Structural Engineers Associations is extremely
saddened with the day's news, including the collapse of the World Trade
Center in New York City. Our hearts and prayers go out to all the victims
and their families.
For additional information, contact the NCSEA Officers and Directors:
President: Greg Schindler (206) 622-5822
Vice President: Mike Tylk (312) 341-0055 x29
Treasurer: Sanjeev Shah (305) 500-9390
Secretary: John Joyce (405) 848-4093
Director: Ron Hamburger (510) 817-3100
Director: Jim DeStefano (203) 254-7131
Past President/Director: Marc Barter (251) 473-8354
Executive Director: Jeanne Vogelzang (312) 372-5708
NATIONAL COUNCIL OF STRUCTURAL ENGINEERS ASSOCIATIONS
203 N. Wabash Ave., Suite 2010, Chicago,
Illinois 60601; www.ncsea.com <http://www.ncsea.com>
