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Cast-in-Place Structures

Photo courtesy of Turner Construction
More than 3 million pounds of concrete and steel are suspended by a super truss in the skybridge connecting the Norm Maleng Building with the existing Harborview hospital.

Harborview Medical Center

Location: Ninth Avenue and Jefferson Street, Seattle

Developer (Ninth & Jefferson Building): Wright Runstad & Co.

Owner (Norm Maleng Building): King County

Developer (Norm Maleng Building): University of Washington Capital Projects Office

Project team: Turner Construction Co., general and concrete contractor; NBBJ, architect; Magnusson Klemencic Associates, structural engineer; Stoneway Concrete and CalPortland (formerly Glacier Northwest), ready-mix suppliers

The Harborview Medical Center project includes a 10-story inpatient hospital called the Norm Maleng Building and a 14-story medical office called the Ninth & Jefferson Building.

The 252,000-square-foot Maleng Building has two floors below street level, including one with eight surgery suites. It connects to the existing hospital through two tunnels and the Ninth & Jefferson Building through one tunnel. It has a six-story skybridge connecting at each level to the existing hospital four stories above the street.

Shoring walls and tunnels for the Maleng Building were created with shotcrete and soil/grout nails, allowing for top-down construction. Permanent foundation walls were made with slip forms, which sped up construction and saved money by eliminating form work. The building’s elevator cores were made from cast-in-place concrete.

The skybridge was made with slab-on-metal decking, with each floor pre-assembled above Ninth Avenue and air-jacked into place, making it a top-down construction. A 52,000-pound super truss suspends more than 3 million pounds of concrete and steel, and braces the existing hospital against earthquakes.

A seismic upgrade was made to part of the existing hospital by wrapping the building skin with a fiber-reinforced polymer that was epoxy-anchored into the existing concrete.

The Ninth & Jefferson Building has 750,000 gross square feet, including 13,300 square feet of retail space and six levels of underground parking for 650 cars. There are five post-tensioned concrete garage floors, five mild-reinforced concrete floors and 10 steel-framed floors with concrete decks.

During excavation, workers used shotcrete with grout nails for the building’s shoring walls. Three-day concrete was used on the parking garage to achieve high strength and allow the post-tensioned cables to be stressed earlier to save time. Colored concrete was used for some of the surrounding site concrete, including inlaid artwork in the sidewalk.

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