Features
It Was a Complex Task
More than a shovel and a watering can were needed to plant this tree in the science complex atrium
BY ANDREW VOWLES
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| This steel tree is a structural and visual centrepiece for the science complex atrium. Photo by Rebecca Kendall |
Who needs a global positioning system to plant a tree? You do when you're the building contractor charged with erecting a 50-ton steel tree meant to support the four-storey atrium roof in U of G's science complex.
Angelo Gismondi, who managed the science complex project until its completion this summer, narrows the space between his thumb and forefinger to illustrate the exacting task workers faced in pinpointing “ground zero” in the 12,000-square-foot atrium to place the fluted trunk of this “tree of life.” Using GPS satellite co-ordinates to position the single steel column just so was only one of several novel aspects of designing, building and installing the tree, says Gismondi, who is now with Innovation Ontario.
As a structural and visual centrepiece for the triangular atrium formed by the three wings of the building, the steel tree soars 60 feet up to the exposed steel ribs of the roof.
“This tree essentially supports the building enclosure of the atrium while providing a grand space conducive to the dissemination of knowledge by fostering a space for collaboration,” wrote the architects earlier this year in a design award submission to the Canadian Institute of Steel Construction.
Speaking before an event held in the spring to christen the new atrium, College of Biological Science dean Mike Emes said the space “has the iconic structure of a tree of life right at its heart, holding up the roof of the building. It's a physical structure and yet it speaks about the life sciences.”
Robbie/Young + Wright Architects came up with the idea of including the tree in the science complex. Richard Young, the Toronto firm's executive director, says the atrium is “the central organ that's necessary for the building to work. It exudes life, and in that context, the tree represents the tree of knowledge.”
The stylized structure was fully installed by the summer of 2006, but it took several companies and numerous workers — and months of painstaking labour beginning in 2005 — to bring it to life.
Working from the architect's drawings, the structural engineering firm Carruthers and Wallace Ltd. assembled specifications and a working design.
The tree itself was built at Walters Inc. in Hamilton. That company used 3-D analysis and visualization software to model the tree and to consult on its design with U of G and the other architects and engineers.
Then Walters went to work to build it. The smooth cylindrical trunk and tapered branches were made from regular steel pipe. But the five nodes — the “crotches” of the branching structure — were trickier, says Gismondi. These specially designed nodes where the tree limbs would be fitted and welded into place were milled in Germany. Operations manager Tim Verhey says this is the first such application of these steel cast joints in Ontario and only the second in Canada.
In parts of the tree, the steel is three inches thick.
Walters set up the tree at its shop for another inspection by the Guelph group before trucking it here in sections on flatbed trailers. A giant overhead crane was used to lower the pieces through the unfinished roof of the atrium.
Erecting the tree itself took 10 days, beginning with the task of bolting the trunk to its concrete base. Gismondi says the contractor used GPS not just to place the tree but also to position other structural elements, including the building's interior columns and a row of outside columns that support the curving front facade of the complex.
It took another six weeks to weld the tree's nodes and branches together. The contractors erected steel scaffolding to keep the parts in place and to provide platforms for welders working on the nodes. “It was fascinating to watch them,” Gismondi says.
Pointing out where the branch tips connect with the atrium's roof beams, he notes that slip joints act like expansion joints in a bridge deck to prevent cracking during freeze-thaw. At the roof, the tree's branches span up to 110 feet across.
He says the indoor steel tree invariably stirs comment from tour groups. Many visitors are surprised to learn that the structure is not merely decorative but that it also holds up the roof.
“It's highly visible, and everybody asks about it — what does it mean, what does it do?”