On the Wings of a Dove
Contractor Takes on the Challenge of Peace Building
by Megan Headley
The new U.S. Institute of Peace (USIP) Headquarters in Washington,
D.C., sits on the Northwest corner of the National Mall, facing the Lincoln
Memorial. The location is visited by millions of tourists each year. The
mission of the national center for advancing the study and practice of
peace building is clear even as one approaches the building, as it is
capped by two curving glass roofs designed to evoke the image of the wings
of a dove and an olive branch.
The design, fabrication and installation of those complex roofs was less
a lesson in peace than it was in patience—and exacting quality control.
Through a nationwide competition, architect Moshe Safdie and his firm
Moshe Safdie and Associates in Somerville, Mass., were chosen to design
the USIP facility. The $110 million, five-story, 150,000-square-foot concrete
structure ultimately consists of three distinct sections linked together
by atriums covered by large-span undulating roofs. The roofs form a dramatic
series of wing-like elements constructed of steel frames and nearly 1,500
white insulating glass units (IGUs) fabricated by Bischoff Glas Technik
in Germany. The IGUs each feature a translucent interlayer and dotted
frit on layer #01 to provide a white glow. The south roof has a 12,000-square-foot
surface area and spans 80 feet between buildings; the north roof has a
7,500-square-foot surface area and spans 55 feet.
seele, a German-owned design-build contractor headquartered in the United
States in New York, was awarded the installation contract in December
2006, starting the long journey from design-assist to completion.
“During the design-assist phase a close collaboration between seele and
the architects was required to develop the desired geometry and meet the
design intent during detailing phase. Many structural members and components
were adapted during this stage,” says Heiko Mertel, the project manager.
As Mertel explains, the architect’s design intent on the USIP was “to
provide a translucent white roof system that minimizes the appearance
of the faceted components, producing a smooth, dome-like structure when
viewed from the exterior.”
It was important that the LEED Silver structure maximize interior daylighting,
but was equally important that the illuminated white dome not outshine
the nearby memorials. As Mertel explains, the design intent specifically
mandated “the intensity of the evening glow of the glass roof will be
closely monitored so not to exceed the lumens produce by the Lincoln,
Jefferson and Washington Monuments.
“The most critical [challenge] for this building was not just to achieve
the highest thermal values, as is standard; the biggest challenge was
to achieve the [correct] lighting so as not to exceed the glow of all
the memorials all around,” Mertel says. It became a balancing act of very
neutral low-E coatings and interlayers.
The fabricated glass underwent a lighting mock-up, in addition to its
performance mock testing and testing for high strength bolts and bomb-blast
calculations. As Marc Zimmer, vice president of operations for seele,
explains, “We developed a matrix of different types of membranes and glass
sizes, and from the matrix we built different mock-ups that underwent
light testing at our facility. We had the whole consulting team, the owner
and the contractor there for the light testing that was performed overnight
in order to see the effects between different types of glass systems and
Design Big-Time Assist/Fabrication
As seele was involved early on in the project, the glazing contractor’s
team played a big role in steering the architect toward the best products
for requirements such as this “night lighting.”
Even as the materials were decided upon—plans quickly changed.
For example, the team quickly found that the roof overhang on the north
side could not be carried on the façade because the façade
was directly above the entrance to the underground car park, supported
on a long-span reinforced concrete beam. Additional loads would have overstressed
As Mertel explains, “The initial design was to bolt roof connections to
the concrete. Due to high shear forces and reduced space (high amount
of rebar), the concrete was not able to allow for bolted connections.
Therefore, we had to redesign the connections with complex embeds.”
The solution was a sliding joint between the inward-curving curtainwall
and the roof construction, so that no loads are transferred from the roof
to the façade.
Multiple-cranked steel sections for the transverse beams were welded together
beforehand and bolted to the intermediate beams via end plates during
erection. Aluminum glazing bars on top, concealed Sefix retainers and
a continuous silicone joint formed an aesthetically sophisticated roof
Installation and Challenges
For the glazing contractors starting construction in June 2009, the USIP’s
prime location meant traffic congestion and difficult access.
“It was a congested site, of course, so we had to deal with just-in-time
delivery,” Mertel says. Adding to the challenge of storing glass materials
onsite was the fact that the deliveries consisted of oversize crates containing
preassembled steel frame assemblies. There was no room onsite for those
deliveries, and barely room on the street for the trucks.
“We had to close down Constitution Avenue,” Mertel says. “We had to get
into the site, which was sometimes very difficult because the site stopped
on the road and we had to tear down fences or things like that to get
into the site—which meant blocking the road.”
Then there were the days where they couldn’t get to the site at all.
“We had to deal with no-work days during public holidays,” Mertel says.
“Usually you don’t think about things like that, you just get deliveries
and start with construction,” he adds.
And then there was the record-breaking snowstorm of 2010.
“We had to stop caulking of the roof and planned for better weather in
spring,” Mertel recalls.
Upon surmounting these challenges, the glaziers, found, naturally, new
“The roof and the curtainwall structure are an integrated structure,”
Zimmer explains. “The roof structure acts as a shelf structure. The scaffold
had to remain up for the whole period of the installation because it was
a support for the roof shell. From an installation perspective, this is
not something where you can dismantle a certain area and turn it over—you
had the full area [scaffolded] for the entire period in order to perform
But in June 2010 the glass installation was complete.
Much like peace building requires close collaboration among all involved,
seele’s managers agree that the collaborative approach among all parties
led to the ultimate success of this project.
“The collaborative approach by all parties in the project … made this
project a unique experience for everyone involved in it,” Mertel says.
Working with BIM
seele had used building information modeling (BIM) software on projects
in the past and was familiar with the new capabilities this technology
“[There] are always going to be different parties driving the BIM approach,”
says Marc Zimmer, vice president of operations for seele, based on his
experience. “There are projects where the owner is requesting the integrated
approach, there are other projects where we’ve seen the general contractor
implementing BIM for coordination purposes.”
In the case of the U.S. Institute of Peace (USIP) headquarters in Washington,
D.C., however, there seemed to be no way to not work with BIM and still
achieve the architect’s vision.
As Zimmer says, “We used BIM modeling because the architectural intent
was a 3-dimensional, complex shell structure that could not have been
devised on paper.”Simplifying the structure might not have been possible
without using BIM to coordinate the thousands of pieces. “We worked with
different shapes in order to develop the roof structure. The final shape
of the wing and the dove was actually devised by the interface of familiar
shapes, like balls, doughnuts etc.,” Zimmer elaborates.
Among the challenges in working with BIM, cautions Heiko Mertel, the project
manager for the USIP project, is taking those difficult-to-design pieces
and turning them into simple-to-fabricate lites.
“In working with BIM, the biggest challenge was from the beginning of
the design to get the geometry into a usable solution that can be manufactured
in the shop and installed,” he says.
Although the company has used BIM extensively on projects—many of the
200 engineers and architects on staff in its Germany office have the capability
to develop BIM models—Mertel points out that the real challenge with BIM
is not the model design, but rather the approach to using the model.
For USIP, Mertel says, “The design phase was unique as it fully integrated
the BIM approach to the project. The final approval for construction was
based on the 3D model and detail drawings rather than a 2D drawing set.”
Zimmer adds, “Different parties need to contribute to one structure that
is going to be incorporated into one model. What we had on this project,
and I think what’s going to be the direction in the future, is that the
approval for starting fabrication was based on the model. In the traditional
approach you would issue the drawing and move forward with the drawing.”
Calling Quality into Question
The just-opened U.S. Institute of Peace Headquarters in
Washington, D.C., features a complex glass roof that might not have been
possible without close attention to quality control. Many professionals
say that improved quality control is one of the year’s biggest architectural
glass trends (see article page
Insulating glass units were fabricated by Bischoff Glas Technik in Germany,
and the structural steel was pre-assembled at seele’s shop in Pilsen,
Czech Republic. Although the oversize crates shipped from overseas would
provide challenges, it’s unlikely seele will fabricate in the U.S. anytime
soon because of those quality control concerns. “Usually with a specialized
glass-steel system, we have very tight tolerances, and so we usually decide
to produce the steel in our own shop to [ensure] the quality … and so
we have the problem with the shipment,” says Heiko Mertel, the project
manager for the USIP project.
“The steel was manufactured with machinery that is being used in the car
industry. We’re using the same tolerances for the structural steel that
we would have supplied to, for example, a car panel—this would be tolerances
in a range of millimeters—which then gives us the opportunity in the installation
phase to make sure that the structure falls into place,” says Marc Zimmer,
vice president of operations for seele. “It’s currently a very limited
number of fabricators that actually apply the high tolerance fabrication
process to structural steel.”
Megan Headley is the editor of USGlass magazine.
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