Parabola cantilever walkway delivers park visitors to the brink.Concerned that visitors to Canada's national parks were becoming increasingly disengaged from both the experience of the outdoors and the reality of climate change, Parks Canada launched a search for private-sector initiatives to reverse the trend toward drive-through tourism. Brewster Travel Canada answered the call with a limited design competition for a walkable structure in Jasper National Park's Sunwapta Valley. "One of the bus drivers suggested that we do something over this particular gorge, Trickle Creek Canyon—something that could be suspended off the side of the mountain that brought visitors into a more intimate relationship with the Athabasca Glacier and its melting," explained Sturgess Architecture principal Jeremy Sturgess. With design-build team lead PCL Construction Management and structural engineer Read Jones Christoffersen (RJC), Sturgess' firm crafted a cantilevered walkway that, clad in weathering steel and glass, defers to its natural surroundings while providing breathtaking views of the glacier and valley floor. Though not a facade itself, Glacier Skywalk warrants discussion within the context of high-performance building envelopes for its innovative structure and streamlined approach to materials—the "+" in Facades+. Though the expected solution to the competition brief was a suspension bridge or other high-masted element, "we thought as a team that this approach would not be appropriate to the site," recalled Sturgess. "As much as we were going to make something courageous and heroic, we also wanted it to be subtle." RJC's Simon Brown came up with the idea of a parabola cantilever that draws visitors 35 meters beyond the face of the cliff. Sturgess Architecture focused on minimizing the material palette, relying primarily on Corten and glass, plus gabion mats filled with local rocks and concrete on the adjoining interpretive walk. "The idea was that the Corten would emulate the ferric oxide outcropping that you see on the existing mountainside," said Sturgess. "We wanted the whole element to feel fractal and extruded from the mountainside. As much as it was clearly manmade, it was to be as sensitive to the local environment as possible." Glacier Skywalk's signature design element is its glass floor, constructed in three layers—two structural, the third designed to be easily replaced if broken or otherwise damaged. "I'm a little nervous about walking on glass floors," admitted Sturgess. Several times he suggested replacing the glass with an opaque material to save money, but the rest of the team refused to let go. "Normally when I've worked in design-build, the gun is to our head and the finger's on the trigger," said Sturgess. "In this case, every time we suggested, 'We can save money here,' everyone on the design team was so in love with the concept, we couldn't lose anything lightly." Sturgess Architecture swapped Rhino models with PCL, RJC, and Heavy Industries, who formed all of the Corten work, throughout the design development phase. "I've never gone through such an extraordinary hands-on design process working with the actual craftsman of the solution," said Sturgess. "This iterative process of working with the team as we crafted every piece kind of by hand—though on the computer—is what led to the success of the project." In combination with its geologically inspired cladding, Glacier Skywalk's minimal structure delivers an illusion of weightlessness that only adds to the sense of exposure. The curvature of the walkway allowed RJC to install a nearly invisible cable suspension system to counterbalance its outward propulsion. "It expresses the thrust from the mountainside, and it does it in a way that makes it feel like a really integral fit with the [landscape]," said Sturgess. "The success is that it's not too much."
Posts tagged with "weathering steel":
Glass and corrugated metal envelop a Scottsdale cycling shop.When debartolo architects principal Jack DeBartolo 3 AIA first visited the site of Bicycle Haüs in Scottsdale, he knew it was exactly what owners Shasta and Kale Keltz were looking for. "In Arizona, with our very intense heat, we love it when we can unite two things: a northern orientation to maximize light without direct sun, and high visibility to the public way," said DeBartolo. "When a parcel's oriented like this, with its main side facing north, it allows us to do both things in one. We can build a glass facade for light and to advertise the contents, and it can also be a view building." DeBartolo's firm designed a wedge-shaped structure with a broad structural glass facade facing the street. The remainder of the building is clad in weathering steel, a low-maintenance material that taps into the desert aesthetic of decay and renewal. "The concept for the building was all about its orientation, and its place, and its environmental response," explained DeBartolo. The architects chose a wedge form for the 5,000-square-foot showroom for several reasons. First, they wanted to maximize glazing on the north-facing facade. "With the shape of the building we collect that northern light and pull it deeply into the building," said DeBartolo. "In the desert, we get a lot of our intense sunlight bouncing off the ground. It also bounces off the ceiling inside the space, so often there's almost no electric light needed in this room." In addition, the building's massing pushes its activity to the street rather than to the back of the lot. Finally, the architects designed the wedge form and a gently sloping roof to someday accommodate solar panels. The 48-foot-wide, 30-foot-tall structural glass wall on the north facade was the product of careful coordination among the architects, engineers, and installers. "What we love, and where we often say less is more work, is that in Arizona we can attach the glass directly to the structural shell using a liquid affixing system," said DeBartolo. Steel tabs welded to the ends of a series of 2-inch-by-6-inch structural tube steel columns receive six-foot-wide panels of low-e insulated glass. Since the glass and steel erectors work with different tolerance levels, explained DeBartolo, "getting them all on the same page early on takes a pretty significant learning curve. You're pushing construction to the max, but we love the overall quality we get when we've literally just glazed the structure." The bicycle shop's mezzanine level cantilevers ten feet over the entrance to create a shaded porch. In addition to providing a space for cyclists to gather before and after rides, the porch "encourages sidewalk activity along First Avenue," said DeBartolo. "That's an important criterion that Scottsdale's trying to push." Corrugated box rib cold-rolled steel, fabricated by Gen3, envelops the building's east, south, and west facades. "The idea was to economize the skin and create a really well-insulated building," said DeBartolo. The architects liked that the steel was available in 30-foot runs, allowing them to avoid horizontal seams. They also wanted "something with aesthetic richness," said DeBartolo. "We try to do everything we can to avoid painting buildings. This weathering steel allows the building to continue to enrich itself as time passes." At the southwest corner of the lot, where team members enter through a back door, debartolo architects carved a notch out of the building's massing, replacing the corrugated envelope with galvanized flat panels affixed with VHB. "We allowed the interior when we cut it away to remain galvanized," explained DeBartolo. "It creates relief, visually, from the harsh exterior." The designers incorporated custom slot windows into the metal facades. "They work really well with our strong western light," said DeBartolo. "We just get little strips of lights rather than a large mass that creates heat gain." The windows are arranged so that they hit the corrugation pattern at the same place every time. They are also integrated with the interior displays, moving up and down to make way for racks of merchandize. "It was very thought through, very methodical, though it created something that almost looks random," said DeBartolo. The architecture of the Bicycle Haüs embodies the owners' passion for cycling. "They really pride themselves on staying state of the art with respect to cycling," said DeBartolo. "In much the same way they wanted the building to really respond to that. Furniture and fixtures define the movement of people, but the space is a lofty room that's almost a gallery for bicycles."