Precast prestressed concrete was found to have the versatility and provided the ideal solution to accommodate the phased construction for the development of an office tower for the Allstate/Oaklands Development. Phase I consisted of a 2 bay - 2 level parking structure built in 2000. Phase II was a 2-storey addition to the Phase I garage completed in the summer of 2001. Phase III, consisting of a 4 level horizontal addition to the south end of the Phase I & II garage, was erected in January 2002.
Phase I provided approximately 350 parking stalls that were increased to 630 by adding the vertical Phase II expansion. The completed structure will provide a total 1100 parking stalls to service the busy office complex (Phases I, II & III). The timing of each phase provided minimal disruption to the in use parking throughout all the additions.
The exterior of the garage used an attractive sandblasted northern pink granite aggregate architectural face mix finish. The exterior cast-in-place concrete stair tower walls were faced with matching architectural precast panels.
A special design feature was the use of load bearing spandrel frames that combined the exterior spandrel panel with integral columns cast on below each end. Each of these frames supports 3 double tee floor slabs. The frames were stacked 4 levels high and were joined together by vertical post-tensioning. The use of the spandrel frames eliminated projecting columns inside at the parking floors.
The parking garage complex was divided lengthwise by an expansion joint running down the middle of the structure. Lateral wind and earthquake forces were resisted by wall frame action in two directions. The open stair towers were independent and not used to resist lateral loads.
Precast prestressed construction provides 18.3 m clear spans consisting of a double row of parking stalls with a two-way traffic aisle down the middle. Access is provided by sloping the precast double tee ramps in the middle two bays. Open stairwells and bearing walls allow light and visibility for interior safety. This arrangement is extremely user-friendly with open column free parking and easy access within the parking garage.
Owner: GWLRA- Great Western Life Realty Assoc.
Project Manager: BFC Buildings/AECON
Architect: Shore, Tilbe, Irwin & Partners
Phase I & II Engineer: Reid Jones Christofferson Ltd.
Phase III Engineer: John Stevenson Assoc.
Precast Contractor: Pre-Con Inc.