An integral part of the Rockyview General Hospital Expansion Project, the new East Parkade is located prominently in front of the hospital along busy 14th Street SW, in Calgary, Alberta. The new precast parkade was constructed into the hillside in front of the hospital, which allowed the first floor to be level with the roadway at the bottom of the hill and the fourth floor to be level with the main floor of the hospital directly across from the Emergency and Admitting areas.
Covered in colored glass and aluminum panels, the precast parkade took on the image of an office building more than a parkade to suit the future clinics addition that will be built on top of the parkade in 2009.
The parkade was constructed to alleviate increased patron and staff parking demands yet keep the parking and future clinics addition centralized to the hospital for easy and direct access to and from the buildings. “The precast concrete structure was not only designed to accommodate the future two-storey clinic addition, but also a parkade expansion to the south” said Doug Little, Project Engineer, “Knowing the future addition on the parkade would enlarge the building massing, and make aesthetics of the front elevation more important, design was focused on the detailing of the precast structure.” Due to its location adjacent 14th Street and the nearby adjacent residential communities, the design underwent considerable scrutiny from the City of Calgary and the Calgary Health Region.
Recessing the parkade into the hill at the front of the hospital involved a complex cast-in-place concrete retaining wall structure with permanent double-corrosion protected soil anchors. Various retaining wall structures were evaluated during design for their economy as well as their impact on the construction schedule and how they integrated with the precast parkade structure. The precast parkade structure was founded on the retaining wall structure and was isolated from the retaining wall by a full-height plenum space to accommodate any horizontal differential movements between the two structures. Approximately two-thirds of the parkade perimeter was enveloped by the plenum, which was capped with precast slabs and wall panels.
Circulation of parking patrons and the future clinics staff vertically within the parkade was achieved using three stair core elements, one of which was paired with an elevator bank. Precast beams, slabs, and walls were integrated and recessed within the footprints of the parkade floor decks to keep the building within the property boundaries and out of the plenum areas around the parkade perimeter. Due to the precision found in the precast shop drawings, it was simple to accommodate the tolerances for elevator recesses, embed plates, and expansion joint assemblies.
Using the efficiency of the end-to-end helix ramping system, the precast structure helped offset the cost premium of the retaining wall system by using a simple repetitive layout. The erection of precast superstructure was found to be most viable to meet the critical schedule that demanded a fast-tracked approach. The parkade deck was constructed with precast double tees and beams with high coulomb rating concrete mixes containing silica fume and a chloride-inhibiting admixture. The dense concrete enables the deck to be resistant to chloride attack and to meet CSA S413 (the Canadian Standard for the Design of Parking Structures) without the need for a traffic deck membrane. “The use of precast eliminated additional maintenance costs and was evaluated using a life cycle cost analysis projected over the 50-year life span of the parkade,” Little says.
To accommodate the future clinics addition, the precast structure was designed to withstand the seismic lateral forces generated from the mass of the precast structure, the steel two-storey addition on top, and a possible precast parkade expansion off of the south end of the parkade.
The use of precast shearwalls was proven to be the most effective means to handle the additional lateral loads from the building and its future additions and was the most efficient system lateral system that allowed the erection of the parkade to flow continuously. The mixing of cast-in-place concrete or steel lateral systems in the parkade would not have allowed the erection to flow efficiently. Using an all precast solution for the structure, the erection flow of the parkade was not hampered by construction using other building materials.
“Choosing a precast solution for this prominent parkade was an obvious choice because of the numerous advantages provided for all stakeholders. Precast was an economical solution that also allowed for a quick erection process which was critical for this fast tracked project” says Little “As well, the precast solution provides superior durability and offers needed flexibility for the proposed future additions.”
The result is a prominent parkade that is now a central feature of the hospital, alleviating parking issues and welcoming patrons and staff, as well as enabling the Calgary Health Region to capture an additional clinics building on the hospital campus without building on precious land reserves.
Architect: Stantec Architecture, Calgary, Alberta, Canada
Engineer: Read Jones Christoffersen Ltd, Calgary, Alberta, Canada
Owner: Calgary Health Region, Calgary, Alberta, Canada
General Contractor: CANA Construction Ltd., Calgary, Alberta, Canada
Precaster: Con-Force Structures Ltd., Calgary, Alberta, Canada
Precast Components: 637 pieces, including columns, beams, spandrels, double-tees, reinforced beams, architectural and structural panels, and exterior walkway slabs
Project Cost: $21 million