April 22, 2009

TILT-UP CONCRETE ASSOCIATION

The Sunset Community Centre in Vancouver incorporates tilt-up technology. The method migrated north from California and is now popular in British Columbia.

Vancouver’s Sunset Community Centre wins 2009 Tilt-Up Achievement Award

PETER KENTER

correspondent

Two Canadian projects — a Vancouver community centre and an Ontario educational facility — were among the winners of the 2009 Tilt-Up Concrete Association (TCA) Tilt-Up Achievement Awards.

The awards honour projects that use site tilt-up concrete — a construction method in which concrete wall panels are cast on-site and tilted into place — to introduce new building types, advance industry technology and provide unique solutions to building programs.

Submissions were judged on aesthetic expression, schedule, size, originality, finishes and special conditions. The winners were chosen from more than 100 projects.

The Sunset Community Centre, a multi-use facility in Vancouver, B.C., incorporates such diverse activities as a gymnasium, pre-school, and youth arts and crafts space.

“We use lot of tilt-up in the Vancouver area,” says Gerald Epp, a partner with Fast + Epp Structural Engineers. “The technique seems to have migrated north from California.

“For a project like this you can achieve better success using tilt-up than poured concrete.

The cost of pouring taller walls is high and you stand less of a chance of getting a good finish. It’s much easier to form on the slab.”

For this project, the interior faces of the panels were left exposed, hand-ground for a smooth finish and treated with a clear sealant to preserve the color of the concrete.

A floating pre-cast concrete staircase was cantilevered from the tilt-up walls.

“The treads were pre-cast and welded to invisible embeds, so it appears that these very thin concrete stairs about six or seven centimetres thick are floating in space,” says Epp.

The main corridors of the building are crowned with skylights and are bisected by a 25-metre-long spandrel beam, more than three metres high and 30 centimetres thick, believed to be the longest of its kind in North America.

“Essentially, all of the walls are curved on top, which is easy to do with tilt-up, because you can pour any shape you want,” says Epp.

“The curved top follows the line of the corridor. The spandrel is the type of structure you usually see going over the top of a window, but in this case we used it in the interior and on top of the lobby space.”

To preserve the architectural integrity of the interior, electrical conduits and some mechanical chases were cast into the walls to hide the services, requiring tight coordination and detailed review on the part of the team.

“It’s interesting to see all of the conduits for electrical, mechanical and radiant flooring being laid out at the time the panels are cast,” says Epp.

With features such as passive daylighting and in-slab geothermal heating, the Centre earned a LEED Silver rating, as well as two awards from the British Columbia Ready-Mixed Concrete Association: a 2008 Grand Award for Excellence in Concrete Construction and a 2008 Award for Excellence in Concrete Construction —Tilt-up Structures.

Another Canadian tilt-up project also earned some hardware.

TILT-UP CONCRETE ASSOCIATION

Humber Institute of Technology and Advanced Learning chose tilt-up concrete for its North Campus Addition because of the speed with which it could be built.

The North Campus Academic and Student Service building of the Humber Institute of Technology and Advanced Learning combines tilt-up wall panels with pre-cast concrete floors. The project was specified as tilt-up from its inception.

“One of the directors at the Institute had made tilt-up one of the requirements of the project,” says William Weima, the project’s architect and designer with Barry Bryan Associates (1991) Limited.

“She wanted to try tilt-up because of the speed with which it can be built. The faster it’s built, you can see the construction budget of the building drop dramatically. It’s interesting, because as the pre-cast slabs are being poured, it looks like nothing is happening on the project, then suddenly, three days later, all the walls are up. To the best of our knowledge, we haven’t seen a three-storey tilt-up building with pre-cast concrete floors.”

The building was initially designed with structural steel framing and joists, but this added to the building’s height and the weight of the panels. Instead, the project was designed to use pre-cast concrete core slabs for the floor.

The three-storey wall panels were first erected and braced using adjustable braces from slab to wall, and temporary perimeter “ring” beams.

The ring beams were connected to interior tilt-up panels and/or structural steel framing, allowing temporary construction loads to be transferred to bracing in the adjacent bays so conventional bracing could be removed and the pre-cast floors could be carefully installed by crane.

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