|The 10-year, $212 million modernization project involved a complete overhaul of the capitol’s building systems, delicate restoration of historical elements, and construction of a foundation system that placed the entire 320,000-sf structure on top of base isolators.|
|Since 1916, the Utah State Capitol building has served as the foundation of Utah’s government, housing the state legislature operations as well as the offices of the governor, attorney general, and treasurer. But after decades of wear and tear and numerous short-sighted modernization attempts, Utah’s rock was on the verge of crumbling.
Mechanical and electrical systems were grossly outdated, hand-crafted ceiling finishes, artwork, and molding were obscured by dropped ceilings, and the structure itself was a moderate earthquake away from catastrophic damage. State officials knew they had to act fast to protect and modernize their treasured capitol building.
The resulting 10-year, $212 million modernization project, headed by Utah’s Architect of the Capitol, David H. Hart, AIA, involved a complete overhaul of the capitol’s building systems, delicate restoration of historical elements, and construction of a foundation system that placed the entire 320,000-sf structure on top of base isolators.
“As far as the attention to historical detail goes, this project is Platinum and at the top of its game,” said judge Tom Brooks, VP of the Restoration Division at Berglund Construction, Chicago.
Life safety was the most immediate concern for the Building Team. The capitol is situated along a 240-mile fault line on the western edge of the Wasatch Mountains that is capable of producing a magnitude 7.5 earthquake.
To ensure that the structure would survive such an event, the structural engineering team of San Francisco-based Forell/Elsesser and Reaveley Engineers, Salt Lake City, devised a seismic retrofit scheme that decoupled the building from the ground using 265 rubber base isolators and 15 Teflon-and-steel friction slider plates. The scheme, which also involved installing concrete shear walls in select areas of the existing structure, allows the building to move up to two feet in any direction.
By separating the structure from the ground, the building will take on just a fraction of the lateral force caused by a seismic event. An 8.0-magnitude temblor, for instance, will feel like a 5.5 quake inside the capitol building.
Inserting the massive isolators and slider plates required the general contractor (a joint venture between Jacobsen Construction, Salt Lake City, and Hunt Construction Group, Indianapolis) to carefully jack the building off its existing foundation of concrete columns and then cut and remove the columns. The 5,000-pound isolators were then methodically installed one by one within the extremely tight confines of the foundation pit.
Modernization and restoration work inside the capitol was equally tedious. The removal of the dropped ceilings left little interstitial space in which to distribute and conceal modern building systems. It was up to the mechanical/electrical engineer, Spectrum Engineers of Salt Lake City, and the architectural team to create noninvasive pathways of distribution within the historic interior to make way for new, state-of-the-art systems, including electrical, lighting, voice/data communications, security, audio/video, plumbing, and HVAC systems.
Where possible, the design team utilized long-abandoned air shafts to distribute systems. In areas where the shafts did not exist, the walls were thickened by eight to 10 inches to accommodate HVAC ducts, plumbing pipe, and conduit for electrical and communications systems. Sidewall diffusers for air and sidewall sprinkler heads prevent interference with the ornate ceilings, while ensuring that the building meets fire code and occupants enjoy today’s levels of comfort.
Distribution of electrical and communications wiring was even more difficult since the wiring feeds nearly every space in the building, including the exterior walls. The design team stacked the communications/electrical closets and used the thickened walls for vertical distribution. Horizontal feeds were accomplished by carefully coring the clay tile ceiling structure and creating channels in the concrete floors.
To minimize disruption to the ornate interiors, the Building Team located most major mechanical systems—including the heat exchangers, pumps, and six air handlers—in a new, mostly below-grade podium building that wraps around the exterior of the capitol. Piping for gas, fire sprinkler, domestic water, heating, cooling, and sewer enter the capitol through a moat. Because the buildings can move two feet in any direction independently from each other, the pipes must be able to move without breaking. Flexible pipe loops make this possible. They form a “U” shape that hangs down into the moat and are constructed with special joints, allowing the required movement.
To meet fire code, fire detectors were required in common areas and corridors—some of the most aesthetically and historically sensitive spaces in the capitol. In lieu of installing traditional detectors that would have compromised the ornate interior architecture, the team specified the proprietary Vesda system from Australia-based Xtralis; this system constantly takes air samples through minute air-collection tubes. Spectrum worked with the architects to conceal the tubes in molding, ceilings, and custom-designed light fixtures.
Even the 103-inch plasma televisions in the House Chamber are designed to blend in with the historic interior. The displays are mounted flush with the finished surface and framed with a historic-looking grille that permits air flow for the electronics and replicates the appearance of other utility openings in the building. Similar grilles were used to conceal modern speakers and other electronic systems, such as security cameras.
This close attention to detail makes the Utah State Capitol project “one of the best” capitol renovations to date, said Reconstruction Awards honorary chair Walker C. Johnson, FAIA. “They revived the building without disturbing the character of the interior,” said Johnson, principal with Johnson Lasky Architects, Chicago. “It was extremely carefully done.”
Utah State Capitol Restoration and Seismic Upgrade
Salt Lake City, Utah
Submitting firm: Spectrum Engineers (mechanical/electrical engineer)
Architect: Architect of the Capitol
Structural engineers: Reaveley Engineers; Forell/Elsesser
General contractors: Jacobsen Construction and Hunt Construction Group (joint venture)
Restoration architects: VCBO Architecture, Max J. Smith Architects, and Schooley Caldwell Associates (joint venture)
Size: 320,000 sf
Cost: $212 million
Construction time: 1998 to January 2008
Delivery method/contract type: Design/build with a guaranteed maximum price