Surrey Central City

Surrey Central City was a powerful catalyst in the transformation of Surrey, British Columbia from a commuter suburb of Vancouver to a thriving urban centre with its own unique identity. The project transformed an existing shopping mall into a high-tech office and university campus.

Alongside Structure Craft as the design-builder, our firm played a key role in the design of three large timber structures for the feature spaces in this facility, each of which broke new ground for scale and complexity: the galleria roof, atrium façade and atrium roof.

The projects demonstrate the value of engaging our structural team early on in the design development process. By doing so, the architect was able to address structural challenges before they became costly interventions – our input improved efficiency, design value and overall flexibility.

Galleria Roof

The heavy timber galleria roof resembles the tall, twisting prow of an overturned boat. This expressive free-form skeletal structure covers a vaulted space between the academic and commercial components of the project and opens to one arm of the shopping mall.

Fast + Epp defined the roof’s complex geometry using 3D-modelling software – extensive design effort was required to develop a single casting that would adapt to the large variation in cable geometry at each of the trusses. Twenty geometrically-unique trusses were assembled on the roof from shop-created components and craned into position. When construction was complete, the existing mall roof was peeled off, creating a dramatic new roof – more than 140m long and up to 28m wide.

The finished roof structure consists of three-dimensional composite timber and steel cable trusses, with spruce glulam top chords and purlins, turned spruce struts and custom castings for the exposed fittings. Because the roof spans two structures that may move independently under seismic loads, one end is fixed while the other rests on slider bearings accommodating up to 300mm of movement in any direction.

Atrium Façade
More than 26m high and 75m long, the glass façade of the entrance atrium curves to embrace a large exterior transit station plaza. Its four-degree tilt minimizes exterior reflections.

Divided by a 450mm-thick projecting concrete canopy, the glazing of the lower portion is supported on spring-loaded stainless steel cables suspended from the canopy, which is in turn supported by a series of 14m-high and 600mm-diameter tapered Parallam columns.

The parallel strand lumber muntins were milled to furniture quality on a lathe custom made for this project, and transfer the horizontal forces from the glazing system to the columns.

The upper façade, while similar, uses smaller but more frequently-spaced columns, which rise from the canopy to meet the atrium roof. Custom castings connect the columns to the concrete at the top and bottom, carrying a 220,000-lb design load.

Atrium roof

This roof covers the grand entrance to Surrey Central City. Because of its complex geometrical shape and varying edge conditions, Fast + Epp considered a tetrahedral space truss to be the most appropriate solution to eliminate as many columns as possible, with a central kingpost-and-cable support.

Given its irregular shape, a normal framed structure would not be suitable. The space truss, on the other hand, provided two-way action and continuous support for the curved roof edge, which cantilevered more than 9m from the supports. Light steel framing helps edge nodes of the truss adjust to the contours of the roof.

The truss consists of 3,700 Douglas Fir peeler core members (a relatively-inexpensive byproduct of the plywood industry). To ensure efficiency and elegance, a series of confined lag screw connectors were custom designed and tested to statistically determine safe working loads. Meanwhile, the chandelier-like king post and cables carefully undergird the truss in the maximum span, prestressed to optimize forces in the peeler cores.