To accommodate the 38 million travelers anticipated to use the facilities annually by 2020, the Minneapolis-St. Paul International Airport is undergoing a major renovation and expansion plan totaling more than $2.5 billion. An integral part of the plan is the new Humphrey Terminal, a 295,000 sq ft (27,400 m²) $73 million reinforced concrete structure that is four times larger than the old facility. In addition to four high-capacity baggage carousels, a restaurant, gift shops, and an in-flight movie rental service, the new terminal offers expanded immigration and customs services for up to 800 international passengers per hour, which is twice the capacity of the previous terminal. In May 2001, 5 gates opened for operation, and 5 more gates will open in Spring of 2002. If needed, an additional 6 gates can be added in the future.

Construction of the new terminal began in August 1999. This was one of over 100 projects that were in progress at the same time, including renovations to the Lindbergh Terminal and expansion of runways and existing parking and rental car facilities. One of the primary objectives was to keep the airport fully operational during construction to serve the current 30 million annual travelers.

Structural Framing System
In the east-west direction, the spans are 30 ft (9.1 m) on center. The spans vary from 30 ft (9.1 m) to 33 ft (10.1 m) in the north-south direction, with some 40 ft (12.2 m) spans on the north end.

Cast-in-place concrete wide-module joists and girders are utilized for the floor system at both levels of the terminal. The joists span in the east-west direction and consist of 5-in. (127-mm) thick slabs on 6.6-in. (2 m) on center. In the north-south direction, the girders are 48 in. (1,219 mm) wide by 19 in. (483 mm) deep. Note that the depth of the girders was set equal to the depth of the joists for overall formwork economy. The depth of the girders is 28 in. (711 mm) where they span 40 ft (12.2 m). Mild reinforcement is utilized in the joists and girders.

To accommodate heavier loads in the mechanical spaces, the depth of the pans is 20 in. (508 mm) and the width of the ribs is 16 in. (406 mm).

Over the ticket counters, the second floor cantilevers 13 ft (4 m). To control deflections, the cantilevered beams are post-tensioned. The remainder of the ticket area and entrance is a two-story open space with 63 ft (19.2 m) spans. Post-tensioned beams span in the long direction.

The floor system is supported on 24-in. (610-mm) square and round columns.

Resistance to lateral loads is provided by moment frames in both directions. Both the structure and façade are designed for wind forces corresponding to Exposure C.

Concrete with a specified compressive strength of 6,000 psi (40 MPa) is utilized for the floor system and the columns. Approximately 24,560 cu yds (18,780 m³) of concrete is used in the terminal building.

Parking Structure
A new 8-story post-tensioned parking structure is planned to be completed in October 2002. The structure consists of a 7-in. (178-mm) thick slab supported on 33-in. (838-mm) deep beams spaced 27 ft (8.2 m) on center. Plans also call for a new light-rail transit station to connect the parking structure and the terminal.

Concrete Versus Steel Framing
The primary reasons that concrete framing was chosen for this project is that the structural engineer wanted to provide the owner with a quality 100-year building. In addition to this, concrete was selected because it provided a stiff structure with low vibration (considering the long spans) and flexibility for future expansions and modifications. Other contributing factors were the long lead times for the structural steel and the inherent noise dampening of the concrete, which is essential at an airport.

Owner: Metropolitan Airports Commission
Architect: Miller Dunwiddie Architects, Inc., Minneapolis, MN
Structural Engineer: Meyer, Borgman and Johnson, Inc., Minneapolis, MN
Construction Coordinator: Kraus-Anderson Construction Company, Minneapolis, MN
Concrete Contractor: Knutson Construction Services, Minneapolis, MN

 
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