Precast Solutions

Fresno Federal
Precast architectural panels create an intriguing, one-of-a-kind facade to exacting building standards in California.
By Deborah R. Huso

Downtown Fresno has never had a reputation for stunning architecture, yet the city is surrounded by a stunning landscape, situated as it is in the shadow of the Sierra Nevada Mountains. Thirteen years ago, when the General Services Administration (GSA) began making plans for a new, larger and stronger federal building, the administration also hoped to create a structure that would stand out on the Fresno skyline, emulate the rugged countryside around it, and create a sense of accessibility to the public. With a limited budget, this was no easy task, but architectural precast offered an economical and versatile option for intricate design, blast and seismic event resistance, and the requisite 100-year weatherability demanded by the GSA.

“Precast offered the material that suited the nature of the region, as well as the needed blast and acoustical qualities,” explains Jeanne Chen, principal of the design architecture firm Moore Ruble Yudell Architects & Planners in Santa Monica, Calif. Blast qualities refer to the blast resistance criteria required for federal government buildings since the aftermath of the Alfred P. Murrah Building bombing in Oklahoma City. Precast concrete provides a hardened, secure envelope and, by its nature, absorbs significant energy and redistributes loads across a broader area. “This was an opportunity to do something completely different with precast,” she says.

Creating panels with random articulation
Precast concrete is not a common architectural component for civic buildings, but in the case of the Robert E. Coyle U.S. Courthouse, it made a lot of sense. “This job had significant challenges,” explains Steve Voss, plant manager for the project’s precast provider Clark Pacific. “Chief among them was the variation of each panel. Randomness was a key objective.”

Joe Healy, project manager with Matt Construction, says that before this job he had worked with precast but only as a structural material. “The facade on this building is about as complicated as precast gets,” he says.

The designers and owners of the federal building wanted to create a facade for the 439,570-square-foot, 225-foot-tall structure that would establish a monolithic, masonry-like look that would take advantage of the light and shadow of Fresno’s powerful sunlight.

“Fresno doesn’t offer a lot of design cues in terms of architecture,” Chen explains, “but the Sierra Nevada Mountains and the agrarian history of the place do.” The designers’ idea was to create a building reflecting the ruggedness of the landscape in the language of abstract texture on the building’s facade, something the general public could see and get close to on a minute scale apart from the grand size and stature of the building as a whole.

“Our intent was for it to be masonry-like without trying to replicate stone,” adds Debra Gerod, a partner with Gruen Associates of Los Angeles, the project’s executive architect. “We wanted a unique-to-Fresno, rustic and western attitude.”

The federal building in Fresno is essentially a steel structure with a precast facade.
“One of the simplest things we did was to come up with repetitive panel patterns that wouldn’t be perceived as repetitive once on the building,” explains Bob Dolbinski, senior associate at Moore Ruble Yudell.

“We used the inherent properties of the precast to create shade and shadow,” adds Chen. The architects wanted to minimize the number of forms needed to create the precast facade while at the same time ensuring the building did not look like a panelized structure.

According to Voss, there were 1,261 panels used in the creation of the building’s facade, and more than 1,000 of those panels were unique. “That’s unheard of in precast because of cost containment,” says Voss. “Our forms supplier had never seen anything like this.”

But the designers got around the cost issue by having Clark Pacific develop about 100 steel forms that could be used over and over for different panels by shifting the starting point in the form to create differently sized and shaped panels. The patterning within each panel has a vertical symmetry that also allows them to be turned 180 degrees to create a different pattern. The longest precast panel was 35 feet.

Dolbinski points out how precast allowed designers limitless possibilities in terms of panel shapes and sizes without the cost that would have been associated with conventional masonry. The panels have a variation in texture of 1 inch in or out, allowing for the intricacies of stone without the associated material expense. A stone facade would have meant another wall system for the stone to adhere to. With precast, the wall system and the facade are both the same. “It’s a one-skin system,” says Chen.

Another big challenge apart from the extensive variation in panel shapes and sizes was the joint size. The architects didn’t want the federal building to look like a panelized structure, so they were opposed to the appearance of joints. As a result, there are no joints in the facade larger than 1 inch, allowing the joints to become a seamless part of the structure’s pattern. The panel joints mimic the 1-inch gaps between patterns.

The panels also had to turn corners about 18 inches, according to Dolbinski, to avoid the look of thin panels and maintain the overall feel of monolithic masonry.

It took nearly six months to fabricate the forms for the panels, and then Clark Pacific allowed for a six-month casting schedule. To save time, the company began erecting completed panels while others were still in casting stage.

“One could have used natural stone, plaster or curtain wall for the facade,” says Voss, “but none of those would have matched the objectives for the look of the building’s skin. If you visit the building at dusk, the complexity of the building’s facade really comes alive.”

Design and erection meet strict standards
GSA standards mandate that a building should have at least a 100-year lifespan – no small request in a seismically active area like Fresno. Precast also offered the much-needed property of blast resistance, something very few other architectural facade components could have provided. Because the panels are large, they allow for greater flexing in the event of a blast.

“Precast is heavier and stronger than stone,” says Togel. “It also offers a more uniform color and is easier to erect.”

“In California, we’re very used to seismic regulations,” points out Voss, “but this job went well beyond the code.” In the case of the Robert E. Coyle U.S. Courthouse, the precast panels can literally be hanging off the building in a seismic or blast event. In a typical precast structure, panels would have been designed to move in such an instance, but the project architects required a maximum joint of 1 inch to maintain the monolithic look of the facade, which meant the contractor had to come up with an innovative solution for meeting the demands of blast resistance.

Another challenge of the project was that spandrel panels had to wrap around corners and switch directions. In a seismic event, panels at corners can smack together, Togel explains, but not fall off the building because they are fastened to the structure via a slip-tilt connection. This makes for a tethered breakaway detail at the cornerstone. If the cornerstones fail, they’ll be caught on a cable.

It took five months total to erect the panels on site. Not only do they exceed building code guidelines, they also offer extreme weatherability.

“Architectural precast is generally 4 to 6 inches thick,” explains Voss. “It’s not perfectly impermeable, but it’s among the very best of materials with regard to weatherability.” He says Clark Pacific tested the panels extensively by trying to draw water through them.

Early collaboration makes the difference
Despite the complexity of the Robert E. Coyle U.S. Courthouse project, the design and construction process was on a very tight timeline. Builders broke ground in April 2002, and erection was completed by the end of October 2003. The building was ready for occupancy by summer 2005. Voss attributes the project’s success on a tight budget and timeline to the collaboration of all involved parties. “Really close communication was imperative,” he says.
Given the intricacy of the building’s facade design, all parties in the planning and construction process had to be willing to work together and willing to confront unique challenges. “You need a precast fabricator who really wants to achieve something different to pull off a project like this,” notes Chen.

She also admits that designers and contractors have to be open to the possibilities of precast as well and think of how to use it in unique ways. “You should avoid thinking about precast stereotypically,” she advises. “It’s a really flexible material if you integrate it into the overall design early on in the planning process.”

Gerod agrees. “The sky is the limit with precast,” she says. “Most people think it demands a certain aesthetic, and often designers think they’re settling on precast. But in reality, it’s an opportunity.” According to Gerod, the designers had planned on using precast right from the start.

Clark Pacific offered advisement and solutions throughout the project, including suggesting the use of white cement to ensure a richer, warmer, more colorfast facade. Dolbinski says Clark Pacific sent the architects some 50 possible color variations for what would ultimately become a rich golden exterior.

“We worked closely with the architects to create ‘engineered randomness,’” adds Thomas Ketron, Clark Pacific’s marketing manager.

“The panels were very big and the design parameters very tight,” adds Voss. As a result, we had 25 engineers working on this job at one time to come up with a solution.”
Of particular concern in any architectural precast project is the fragility of the panels in transport since, unlike structural precast, the panels are not reinforced with rebar. “You need to agree on a process beforehand for repairs and standards for rejection of damaged panels,” Togel points out.

“You can’t start planning a process like this too soon,” adds Healy, “especially in an area where there are seismic design considerations.”

The Robert E. Coyle U.S. Courthouse’s design has won numerous awards, including the GSA Design Excellence Honor Award in 2006-07 and the Precast Concrete Institute Design Award in 2005. “Precast gave us so much more flexibility for this project,” says Chen. “We created an architectural language that you won’t see anywhere else.”