|Thanks to a $55 million upgrade, the Veterans Affairs San Diego Healthcare System Building 1 can now withstand a 7.2 magnitude earthquake. The 920-day project concentrated on installing new foundations and exterior stair towers with integrated braced framing. Additional work focused on utility upgrades, core strengthening of the penthouse structure to the surrounding building, and beefing up particularly vulnerable areas, such as interior bridges, roof corners, and balconies.|
|Three decades after its original construction in the early 1970s, the Veterans Affairs San Diego Healthcare System Building 1 fell far short of current seismic codes. This not only put the building and its occupants—patients, doctors, nurses, visitors, and administrative staff—at risk in the event of a major earthquake, it violated a California state mandate requiring all hospitals to either retrofit or rebuild. In 2005, VA administrators opted to retrofit the six-story, 855,000-sf hospital—and remain open throughout the course of construction.
Most of the work concentrated on installing new foundations and exterior stair towers with integrated braced framing. Additional work focused on utility upgrades, core strengthening of the penthouse structure to the surrounding building, and beefing up particularly vulnerable areas, such as interior bridges, roof corners, and balconies.
The building’s eight exterior stair towers were completely demolished, but in phases, to keep the hospital operational. Replacement stair towers were built atop new, deep foundations and connected to one another by a braced-frame structural steel system. The brace frames provide the hospital’s critical seismic strengthening through continuous slab edge connections. Value engineering turned the brace frame structures into architectural elements: metal cladding was originally going to be the finish material, but after that idea was abandoned, the criss-cross steel was left exposed and painted white.
It is the staircase structures as seismic solutions that really caught the judges’ attention. Summing up their thoughts is Lucien Lagrange, AIA, principal at Chicago-based Lucien Lagrange Architects, who characterized the engineering as “quite amazing.”
Along the way, more than 1,100 tons of asbestos were removed. MRI facilities had to be relocated during construction so cranes and steel didn’t interfere with the machines’ calibrations and accuracy. Undocumented structural steel was discovered embedded in concrete, while an undocumented sewer lateral was discovered after it was hit and filled with slurry.
Collaboration between the Building Team and the hospital staff allowed the challenging project to be finished months ahead of schedule and with minimum disruption to the hospital.
VA San Diego Healthcare System Building 1 Seismic Correction
La Jolla, Calif.
Submitting firm: Clark Construction Group (GC)
Architect: Leo A Daly
Structural engineer: Nabih Youssef & Associates
M/E engineer: S&K Engineers
Geotechnical consultant: Ninyo & Moore
Area: 855,000 sf
Construction cost: $55 million
Construction time: November 2005 to April 2008