May 6, 2009

The CBC/Radio Canada Broadcast Centre project was financed in part by the sale of parking space for condo towers.

CBC/Radio Canada Broadcast Centre carries on during rebuild

DON PROCTER

correspondent

After almost three years of construction and renos, the makeover of the 246,000-square-foot CBC/Radio Canada Broadcast Centre in downtown Vancouver is nearly completed.

Engineering the new structure in a fashion that could be built with minimal disruption to the existing CBC operations has been a big task.

“We had to devise solutions to help the contractor foresee the challenges (eliminate construction surprises) more so than you’d require in a typical building,” said Rob Simpson, principal of Glotman Simpson Consulting Engineers, the structural engineers on the project.

The consultant was fortunate to have a good set of existing drawings of the building since many existing buildings have poor drawings.

It allowed the company to visualize the modifications required in many areas of the existing building.

Still, the structural design wasn’t straightforward. Among the challenges was designing the new 21,000- square-foot HD (high definition) newsroom above existing studios.

The trick for Glotman Simpson was to engineer a substructure within the confines of existing space, which could be built without disturbing ongoing operations.

Complicating matters was the fact that the new space had to meet current seismic standards.

It was a challenge because there was only one existing elevator core to potentially provide lateral resistance, said Simpson.

To carry the vertical loads through the building, seven large round cantilevered concrete columns became frames to support the new roof and also to provide lateral seismic resistance.

Columns were installed by making relatively small openings through flooring and on the outside of the walls of existing studios.

The columns rest in new footings well below grade, he explained.

Half of the new newsroom floor is built on columns that transfer on a new parking deck while the other half of the news floor is voided and built atop an existing landscape deck.

The latter section of flooring is raised as much as four to five-feet, allowing plenty of plenum space for future utility reconfigurations.

The configuration and installation of the newsroom’s electrical was tricky because of HD requirements, said David Crilly, one of two project managers for general contractor Scott Construction.

Electrical contractor Mott Electric installed technical power, house power and two back-up power systems.

A major hurdle was that all the utilities — including mechanical — serving the studios, production offices and individual work spaces, were to be inserted in separate cable trays and conduits in one raised floor system.

“Trying to configure the placement of mechanical and these extensive electrical systems was a true 3D problem,” said Crilly.

The design and installation of the acoustical system to meet the sound-deadening STC 60 rating also presented perplexing problems.

Essentially, sound studios, editing suites and production offices had to be sound isolated from the rest of the building.

Simpson said that the project is one of the few times a series of planters in concrete have been engineered on top of a steel building.

Steel buildings generally are loaded with lighter roof designs because it is costly to engineer steel for higher roof loads.

“The original purpose for the planters was to satisfy city concerns for some greening on the roof for people viewing the roof from nearby highrises,” said Simpson. “(The steel design was) reasonably economical and is a tribute to great teamwork and collaborative efforts with the architect.”

The CBC redevelopment is a design by Hotson Bakker Boniface Haden Architects.

The firm’s design re-engages the centre with the street, in part by creating a public entertainment area (an outdoor performance studio and stage on the plaza available to non-profit organizations).

Furthermore, the studios have been moved to the corner of Vancouver’s main downtown corridor, Georgia Street, where the production of news programs will be visible from the street.

The one square block redevelopment also includes the construction of two condo towers by Concord Pacific Group Inc. CBC sold the density of its parking lot to the developer to build towers and the sale has helped finance the redevelopment.

Crilly said that the CBC project was a bigger challenge than he’s faced in more than 20 years in construction.

Time windows for construction were often small — in some cases only an hour in between on-air-programming.

“One of the problems is that we had to keep CBC on the air, without Scott Construction getting on the air,” he said.

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