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Buildings
Building for a Secure Future: Government
(enr.com
and archrecord.com - 3/25/02 issue)
By Joann Gonchar, ENR
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| GUARDED
Design based on prior attacks. (Photo courtesy of NBBJ)
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One of the biggest challenges facing
designers of U.S. embassies and other federal facilities is
the retrofit of existing buildings to meet tightened security
standards. But officials say that for the design of newer
buildings, tougher criteria have been in place for years.
"We already had a heightened posture toward security,"
says Charles E. Williams, director and chief operating officer
of the U.S. State Dept.'s Bureau of Overseas Building Operations,
Washington, D.C.
For the U.S. General Services Administration,
the 1995 attack on the Alfred P. Murrah Federal Building in
Oklahoma City was the "defining moment," says Ed
Feiner, chief architect at GSA, also in Washington. The Sept.
11 attacks on the World Trade Center and the Pentagon "accentuated
the need to move forward with what we had already started."
In 1999, GSA shifted from prescriptive
security guidelines to performance-based standards. For each
existing or new facility, the agency develops a risk assessment,
taking into account potential natural disasters, accidents
and deliberate attacks, says Wade Belcher, GSA's manager of
security design standards.
Changes have not been made to projects
under way in response to Sept. 11. Those attacks "showed
how airplanes can be used as weapons," says Rick Thomas,
GSA project manager in Seattle for the 23-story, 615,000-sq-ft
federal courthouse there. "The best way…to deal
with this kind of hazard is to enhance security within airplanes,"
he says.
The building, designed by local architect
NBBJ, is slated for completion in 2004. Its security criteria,
developed after studies of prior terrorist acts, include a
structural system designed to help resist progressive collapse–a
much-discussed topic since the 1995 and 2001 attacks.
Jon D. Magnusson, chairman and CEO of
the courthouse's structural engineer, Skilling Ward Magnusson
Barkshire Inc., Seattle, says one strategy to resist vertical
progressive collapse is to use strong horizontal ties that
transfer loads from the damaged area to other members of the
frame. Chances of horizontal progressive collapse are minimized
by very strong vertical elements that act as stops, or actually
weakening horizontal ties, he says.
Engineers agree, however, that in designing
a frame to resist an attack, much depends on the type and
power of the weapon, how and where it is delivered, the force
of impact, whether there is ensuing fire and other factors
difficult to predict in advance.
The retrofit of existing buildings to
resist progressive collapse is even more tricky. For steel
structures, moment rather than shear connections are the answer,
say engineers. For concrete buildings, with connections embedded
within the structure, the preferred method is wrapping columns
with carbon fiber or steel jackets, says Robert Smilowitz,
a principal at Weidlinger Associates Inc., New York City.
GSA's "biggest problem" is
vulnerable existing stock–and not just structurally.
Quick fixes, such as barriers to keep vehicles at bay, create
the appearance of a government under siege, says Feiner, and
that is not acceptable in the long run.
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| COMPOUND
Embassies outside cities are more out of harm's way. (Rendering
courtesy of Hellmuth Obata & Kassabaum) |
Since Sept. 11, GSA has held design
charettes in New York City, Boston, Chicago and other cities,
to address perimeter security and develop short-term and long-term
solutions for specific facilities. Security is in part an
urban design problem, says Gary Haney, a design partner in
the New York City office of Skidmore Owings & Merrill.
He attended a charette for a courthouse in Alexandria, Va.,
which is a selected site for trials of accused terrorists.
Private landlords and developers could
also feel the impact of this new scrutiny of existing buildings.
Earlier this month, the GSA proposed that the federal Interagency
Security Committee develop guidelines for space the federal
government leases from the private sector. The GSA leases
some 150 million sq ft across the country.
In the 2003 budget, GSA is seeking $986
million for repairs and alterations, up from $869 million,
and $400 million for security, up from about $300 million.
The State Dept. is seeking $1.3 billion for embassy security,
construction and maintenance, up 2%. Within that total, $609
million would go for capital projects, down 8% from 2002.
Aid for improved perimeter and compound security would rise
7%, to $146 million.
Thirteen U.S. embassies are in design
or construction. Two are replacement facilities for the embassies
destroyed in Nairobi, Kenya, and Dar es Salaam, Tanzania,
by bombings in August 1998. Both are slated for completion
in early 2003.
Before year-end, contract awards are
likely for embassies in Conakry, Guinea; Phnom Penh, Cambodia;
Tashkent, Uzbekistan; Harare, Zimbabwe; Cape Town, South Africa;
Yaoundé, Cameroon; and T'bilisi, Georgia. The OBO plans
to use standard designs for small, medium and large buildings.
The method should accelerate construction since "we won't
have to go back to the drawing board each time," says
Williams. Designs will be adapted to climate and site conditions.
An embassy for Berlin has been stalled
since 1996, when the State Dept. selected a design team led
by Moore Ruble Yudell Associates, Santa Monica. The site,
on Pariser Platz near the Brandenburg Gate, would not allow
for a 100-ft setback generally required since the 1983 U.S.
embassy bombing in Beirut. In 1999, the Senate Appropriations
Committee, citing security concerns, said the land should
be sold. But the project "is still programmed on the
site that was selected," says Williams. "We are
working through all the design and host-nation related issues."
John Ruble says his firm is working
on bollards and planter boxes, gates and a non-climbable fence
that would protect the building from vehicle and pedestrian-delivered
explosives, yet still be sensitive to the historic site. The
embassy needs to project an image that is "strong but
not hostile," he says.
The Berlin project is a special case.
For most embassies, the State Dept. avoids setback problems
by locating facilities on compounds outside of city centers.
While such facilities are sometimes less accessible to users,
four to 12 acres are easier to acquire outside downtowns,
says Bill Stinger, senior principal in the Washington, D.C.,
office of architect-engineer Hellmuth Obata & Kassabaum,
which is working on several embassy projects. The State Dept.
must balance land requirements and accessibility with security,
he adds.
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