September 25, 2003

A structure built for healing

Photo courtesy of UW A two-level glass pedestrian bridge connecting the surgery pavilion to Muilenburg Tower (right) offers views of the surrounding landscape. The bridge has a slight slope to accommodate the different floor-to-floor heights of the two buildings.

Many factors affect the healing process. Doctors rely on new technologies, procedures and medicines to help patients recover. As the medical industry has grown, more emphasis has been placed on the hospital environment itself in aiding the healing process.

When it came time to design the University of Washington Medical Center Surgery Pavilion, one of the main goals was to incorporate the structural aspects of the building into the university’s mission to care for patients. The result is a landmark addition to the south campus that retains the main elements of the existing location while creating a healing environment for patients.

Maintaining views

One of UW’s first design criteria was to retain the glade, a landscaped area south of the medical center, used as a “healing garden.” The surgery pavilion fits into the site, complementing the glade and the landscaping along Montlake Boulevard Northeast and Northeast Pacific Street.

Two levels of medical floors contain large cantilevers to afford a view of the glade through a sloped curtainwall system. Post-tensioning was added in the structural slabs of these areas to address deflection and long-term creep concerns.

With its curved-roof design, the building also respects and preserves the Rainier Vista view, another signature feature of the campus.

The surgery pavilion has its own identity and purpose, without conflicting with the strong massing and architecture of the adjacent Muilenburg Tower or surrounding neighborhood. The civil landscape of the project keeps it relatively hidden behind rows of beautiful foliage.

Light-filled areas

Glass panels on the roof allow a flow of natural light into the facility to aid patient recovery. The design incorporates a C-shaped base constructed of exposed structural concrete walls and a curved roof with skylights. This creates a warm, light-filled waiting area for patients and visitors.

A glass pedestrian bridge connecting to Muilenburg Tower provides a majestic view of the glade and surrounding landscape. The bridge’s transparency is preserved through the use of precise concrete segments kept at the minimum thickness requirements. The bridge is framed with two levels of precast concrete segments suspended at 12 feet on center from a pair of 5-foot-4-inch-deep steel girders at the roof level.

Surgeons will benefit from the large operating rooms, spacious enough to house state-of-the-art medical equipment that can be voice-operated.

Structural challenges

The surgery pavilion houses three floors and 160,000 square feet of functional medical space constructed over three floors of below-grade parking for 275 cars. A large mechanical floor located over the south half of the top medical floor contains the majority of the air-handling equipment.

Due to its proximity to Muilenburg Tower, the facility posed many structural challenges, including that of designing a structural floor system shallow enough to allow adequate space for needs within the ceiling space. Floor-to-floor heights within the Muilenburg Tower are 12 feet.

By incorporating a gentle slope into the bridge structure to provide the pedestrian link between the two buildings on two levels, a 13-foot floor-to-floor height was created on the medical-floor levels of the surgery pavilion.

The structural system selected for the medical floors was a 12-inch-thick two-way concrete slab. The slab incorporated conventional steel reinforcing to avoid using post-tensioning strands that would limit the future flexibility to sawcut or core-drill the slabs. This structural system yielded the shallowest system and provided a flat obstacle-free soffit to maximize the available ceiling space to run ducts, conduit and piping.

The below-grade parking levels are constructed of two-way bonded post-tensioned concrete slabs. This type of construction provided the shallowest structural system and the most cost-effective means to frame the garage. Floor-to-floor heights in the garage are 8 feet 9 inches.

To maximize the value engineering, a hybrid of structural systems was used within the building. Cast-in-place concrete was used up to the upper medical floor and structural steel framing was used above, which reduced construction costs and time.

The building mass was also reduced, which provided reduced foundation and seismic loads. Lightweight concrete used on the mechanical mezzanine level eliminated the need to spray-fireproof the steel deck soffit, making it easier to build attachments suspended below the slab. Spray-fireproofing otherwise needs to be scraped away and patched to allow attachments.

Soil-nailed basement

Deep excavations and a close water table at the site provided a challenge for the basement walls and excavation design. A shotcrete, soil-nailed system was selected for the majority of the building.

To reduce construction costs, the basement walls were combined with the soil-nailed walls, creating a single shotcrete wall that provides both the temporary excavation shoring and permanent basement walls. Underslab drainage is provided under the lowest parking level to intercept groundwater.

Lateral seismic and wind loads in the building are resisted by special moment-resisting frames above the upper medical floor. These frames utilize reduced beam-section connections to ensure ductile behavior of the steel moment frames. The lateral system on the lower levels is provided by perimeter and interior concrete shear walls.

Communication and strategic thinking were keys to the success of the design team. Frequent design meetings between the design team and the university helped along this complex project.

Introducing a general contractor/construction manager early into the design and construction process also contributed greatly to the outcome of the project. The surgery pavilion is sure to provide the UW Medical Center a valuable space to care for patients for many years.

Other Stories:

• Ingenuity you won’t see
  
• Designing a site for sore eyes
  
• Keeping the lights on