Edmonton International Parkade

A. D. WILLIAMS ENGINEERING

The design-build project for a four-level, 1,800-vehicle parking structure at Edmonton International Airport has been so successful that its innovative design and construction method (named the “ADF System”) is being marketed throughout North America.

The owner wanted a grid spacing of about 18.3 x 9.15 metres. The aim was to reduce columns and therefore obstructions to the parking flow.

Typically such a design would use precast pre-tensioned double tees spanning 18.3 m, supported by girders and beams spanning 9.15 m. However, the team had discovered a tower crane was available at an economical price and decided to take advantage of it. The crane could service virtually the entire construction site, had substantial size and capacity, and was capable of multi-tasking. However, its use also meant that the maximum span for the tees could be 9.15 m.

The team therefore decided to reverse the framing orientation of the structure. Although it may appear counter-intuitive, the approach had many advantages that outweighed the disadvantages:

customized steel forms for the girders, with an aesthetically pleasing configuration, were cost-effective due to multiple reuses

arching of the girders afforded greater clearance height in drive aisles

forms could easily be altered to achieve drainage slopes within the primary structural components

precast tees were flush-framed to minimize floor-to-floor height and the length of sealant joints

frames were designed with optimal inflection points to allow for a “drop-in” segment, facilitating crane operations

the long-span frames were better oriented to resist lateral and seismic forces

9-metre spacing of the frames allowed for the use of smaller, more easily handled tees and spandrel sections.

the design afforded rapid turn-around time of 24 hours for casting the girders

girders and columns were highly reinforced and used prefabricated reinforcement cages.

By using the large-capacity crane, the team could precast basement walls on site and have the exterior stairs partly shop-fabricated. Another advantage of the adopted approach was enhanced durability. The precast tee-sections are highly resistant to chloride attack, and the assembly that keeps the tees in place involved only one weld.

The result is a parkade with wide aisles that create a sense of height and openness. And, despite a major redesign to allow the parkade to be expanded in the future to hold 4,000 vehicles, the parkade was completed within the original budget estimate, and opened on schedule in December 1998.CCE

Client: Edmonton Airports

Prime consultant, structural, mechanical and electrical: A.D. Williams Engineering. Structural team: R.J. Gillis, P.Eng., Clayton Matwychuk, P.Eng., Nathan Loewen, Larry Schmidt, Greg Quirke

Design-Build Contractor: Forest Construction (now PCL Construction)

Architect: Henderson Inglis Partridge