1973:
The World Trade Center is Completed
LERA
photo
One of many innovations that Les Robertson brought to the design of the World Trade Center were mechanical damping units to reduce the giant towers' proclivity to sway in the wind.
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Structural Engineer
and Berkeley alum Leslie E. Robertson (Civil Engineering, '52) and
architect Minoru Yamasaki blended form and function in this 110-story
feat of structural innovation. With his structural engineering firm,
LERA, Robertson has since designed three of the six tallest buildings
in the world.
In the late 1960s, faced with the challenge of building what
was then to be the tallest skyscraper in the world, Robertson
and his colleagues employed a lightweight hollow tube design that
could handle the weight of the buildings while bracing it against
the wind. Other skyscrapers of the time, including the Empire
State Building, employed a skeleton frame of I-beams. Each of
the Twin Towers, however, consisted of a structural steel core
running up the center of the building and an exoskeleton of 14-inch
square steel columns that snake up the façade every 40
inches. For the first time, fire-rated partition walls, now an
industry standard, replaced standard masonry and plaster enclosures
for elevator shafts and stairs. The structures were built to withstand
the impact of a Boeing 707, then the largest bird in the sky.
PBS's
"Wonders of the World" Databank entry on the WTC
Leslie E. Robertson Associates,
RLLP
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© 2001 UC Regents.
Updated 11/15/01.
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