Surrey Central City - Galleria Roof
We designed, fabricated and erected three sections of Central City in Surrey, B.C. – the Galleria roof, the Atrium Roof, and the Atrium's North Façade. Because the architects brought us in during the design phase, tremendous flexibility was gained in addressing the structural challenges presented by each project. The innovations achieved on these projects, though costly in a conventional scenario, paid for themselves through better design or improved efficiency during construction.
The completed 450-foot long Galleria Roof covers a serpentine-shaped, five-storey high vaulted space between two buildings in the middle of the Central City development. The roof had to be constructed above an existing shopping mall, which remained fully operational throughout construction.
We wanted to build something that was a logical response to the complex geometric form designed by the architects. Our solution was an expressive skeletal structure consisting of 3-D composite timber and steel cable trusses.
An example of the challenges we faced was the design of a fitting at the bottom of the central struts. The result of our labours was a single casting, which accommodated every condition for the highly variable geometry of the cables.
In order to give confidence that the 20 large irregular trusses would fit together in the field, we relied heavily on 3-D solids modelling and the hundreds of precise shop drawings created from the central parametric model.
After overseeing the production of all components in our shop, assembly of the trusses on site proceeded using a dedicated crane and an adjustable assembly jig. Each finished truss, complete with a section of the shiny central rib, took about four days for our crews to assemble.
The 3-D truss sections were quite large – 20 feet wide, up to 90 feet long and 30 feet high; they were asymmetrical, awkward to deal with, and weighed up to 25,000 pounds. We had done the modelling beforehand and knew they would fit, even with the very tight tolerances. Still, when we saw them begin to nestle into place we breathed a little easier.