Award of Excellence: BC Place Revitalization

BC Place Stadium is a 54,000 seat sports and entertainment centre that opened to the public in the early 1980s. By 2008, with the approach of the 2010 Winter Olympic Games, BC Pavilion Corporation (PavCo) engaged GENIVAR and Geiger Engineers to analyze the possibility of revitalizing the existing stadium as an alternative to demolishing it and rebuilding facilities elsewhere. Their analysis showed that the primary systems in the building were very serviceable, with the notable exception of the air-supported roof.

Renovating the building, including installing a new gravity supported roof, was estimated to be less than half the cost to demolish it and develop a new stadium elsewhere. The decision to refurbish also meant the stadium could keep its downtown location which is one of its greatest assets. Also, the environmental impacts of demolition and redevelopment would have far exceeded the environmental cost of revitalization.

For the revitalization, the stadium’s existing air supported fabric roof structure was replaced with a gravity supported fabric roof. The roof is the largest cable supported retractable membrane roof in the world and the first of its kind in North America. The structural concept had been used for several stadia in Europe but had not been previously incorporated into a roof of this scale both from a size and a loading perspective. GENIVAR was structural engineer of the base building upgrades as well as mechanical and electrical engineer for the project. Geiger Engineers were structural engineers for the new roof.

The design was challenging because the new roof was placed on a base building that had not been originally designed for a gravity roof system. This meant dealing with increased gravity loads on the existing building, as well as the geometric challenge of placing the idealized circular shape of the new roof on the elongated flat oval shape of the existing stadium.

In order to achieve a lightweight design the project team selected a membrane roof supported on post-tensioned cable trusses. The cable truss system consists of 18 cable trusses having spans varying from 227 m to 186 m. The cable trusses are supported by 36 perimeter steel masts rising 47.5 m above the original roof’s concrete ring beam.

The stability of the entire system is provided by a continuous steel compression ring forming an approximate circle to the outside of the steel masts at 18 m above the original roof’s concrete ring beam. This is balanced by a tension ring consisting of 10 cables located in a two tier grouping which form an approximate circle to the inside of the steel masts at the base of mast level.

The resulting cable truss system provides a flexible vertical and lateral load carrying system which gains its stability from the force couple of the opposing compression and tension rings.

Another technical challenge for the structural engineers was the lateral load analysis. They developed several computer models and based on the analyses, vertical eccentrically braced frames were incorporated into the roof. Also, the top level of the shear walls in the base building were replaced with buckling reduced braces in order to limit the seismic forces transmitted to the roof.

A full revitalization of the building mechanical and electrical systems was undertaken. One significant impact was the change from the pressurized conditions associated with the former air-supported roof and the atmospheric pressure environment of the revitalized facility. The adaptations involved decommissioning and redeploying numerous pressurization fans. The snow melt system that had been incorporated with the air-supported roof was also decommissioned. All these modifications, including significant upgrades to the electrical systems, resulted in cost savings for the owner.

The project was done in two phases, with the interior upgrades completed in time for the 2010 Olympics and the structural changes completed in approximately 18 months by November 2011.

The stadium can now continue to be a gathering place for British Columbians and its iconic shape continues to define Vancouver’s skyline.cce

Name of project: BC Place

Revitalization, Vancouver

Award winning firms: GENIVAR,

Vancouver – prime consultant, structural, mechanical, electrical engineering and Geiger Engineers, Suffern, NY – roof structure design (Glenn Hubick, P.Eng., David

Campbell, P.E., Karen Lynch, P.E.,

Adam Patterson, EIT, Seann Caldwell, P.Eng., Arnold Con, P.Eng.)

Owner/client: B.C. Pavilion

Corporation (PavCo)

Other key players: Stantec (architect), Thurber (geotechnical), Schlaich

Bergermann (specialist), Cannon Design

(sports architect), Acoustical Design

Group (acoustical); CM King (lighting)

Contractor: PCL Constructors West Coast

JUROR COMMENTS

This is a complex and challenging project. It combined aesthetic qualities and significant innovations related to the roof and lateral load resisting structural systems, as well as innovative mechanical and electrical systems. Moreover the project was integrated into its urban location, while respecting the environment.