Tuesday, October 22, 2019

Vancouver House's elegant, expanding form dramatically adds to city skyline

Compared with other highrises in Metro Vancouver, the 60-storey condo tower is unique.

Vancouver House is more than just another condo highrise, it’s become a building that almost everyone has an opinion about. Some love it for standing out in a sea of rectangular cuboid towers; others hate it as a symbol of the city’s real estate mania.
The first residential move-ins are expected next month, four years after construction began in 2015.
From the start, the 60-storey Vancouver House hasn’t been a typical condo project.
The differences that set it apart include how the unique challenges of the site were solved by a Danish architect and the contradiction between looking unsteady but being built to withstand double the most extreme earthquake predicted for Vancouver.
The site is one of a handful singled out by the City of Vancouver for special treatment. Situated by the southbound Howe Street on-ramp to the Granville Street Bridge, it was designated for a tall, distinct building at a gateway to downtown.
But the parcel of land at 1480 Howe St. had one big drawback: Its rectangular shape was reduced to a triangle because of a 30-metre safety setback from the bridge.
Architect James KM Cheng worked on a design for almost a year-and-a-half for Westbank Corp., the Vancouver-based international property developer behind Vancouver House.
“We were thinking what could be done as a triangle building,” he said. “You need a bigger building to make it financially economical. By the time you finish the elevators and exit stairs, you have nothing left to build condos.”
In Metro, Cheng’s work is a dominant presence. He’s designed as many as 60 highrise condo towers in Vancouver and virtually invented the typical tower and podium design associated with Vancouverism, the contemporary urban design developed in the city that emphasizes public space and walkable neighbourhoods. For Westbank, James KM Cheng Architects had already designed several high-profile towers, including Shangri-La, Fairmont Pacific Rim and the Shaw Tower.
Cheng was struggling with the site when he heard Bjarke Ingels, a rising international architecture star, give a talk at the Urban Land Institute in 2010. Cheng remembered sitting in the audience and thinking: “This is one of the smartest young architects I’ve ever listened to.”
At that time in his career Ingels hadn’t designed a highrise condo tower. That didn’t bother Cheng. He was confident that Ingels would come up with a successful design and help push local architecture beyond the conventions of Vancouverism.
He suggested to Ian Gillespie, president and founder of Westbank, to give Ingels a chance. Gillespie had already met Ingels and was impressed with the Danish architect.
“If you like it, use it,” Cheng said to Gillespie. “If not, I can still do the building for you.”
When Ingels went back to his office in New York after visiting the Vancouver site, uppermost in his mind was the 30-metre setback from the bridge and not casting a shadow on the park to the west.
He said the usual process with his firm is almost Darwinian: Many options are explored before a final design emerges. That didn’t happen with Vancouver House.
He met with his team on a Sunday. Ingels took a rectangular piece of foam used to make architectural models and drew a line in an arc from a triangle to a rectangle. In a rare event, Ingels cut the foam himself. He was surprised when the crude model stood on its own even though it looked unstable.
“It was literally one of the few times in my career where we had a hole-in-one,” he said. “We just knew that this was the idea.”
Ingels realized the 30-metre setback didn’t extend all the way upward. Once the building cleared the bridge deck by 30 metres, it satisfied the city’s safety requirement. What the expanding tower also did, Cheng said, was give Westbank more valuable real estate at the top, where the views are the best.
By gradually growing the area of each floor rather than abruptly expanding out to the full rectangle once the tower rose above the safety setback, the innovative design created an elegant form. Inside, it created floors that are a different size on each level. Most residential towers have 12 different suite designs; Vancouver House has 220 designs for just under 400 suites.
The distinctive pixelated facade not only makes Vancouver House look contemporary, it also creates deep balconies with overhangs that act as passive cooling to shade suites from the sun.
It was up to structural engineers to translate the unusual geometry into a functional building.
Geoffrey Poh is the project engineer with Glotman Simpson, the Vancouver consulting engineering firm that has a history of working with Westbank. He explained that a typical highrise tower rises straight up with floors on top of vertical columns. The loading, due to gravity, is vertical and downward.
The geometry of Vancouver House, however, means it also has permanent lateral loading, a horizontal force that varies in intensity from floor-to-floor. Engineers compensated for that outward push, which includes taking into account wind and seismic events, by creating a super-rigid core for the elevators and stairs offset from the centre of the building.
A big part of creating that rigid structure included adding a bigger concrete foundation weighing several million kilograms underneath the seven storeys of underground parking. In most high rises, the foundation would extend about three metres around the elevator core. In Vancouver House, the foundation is almost 90 per cent of the area of the top, rectangular floor.
Poh compared the extra weight in the foundation as a way to balance the building — similar to how a big helps to balance the body.
Embedded in the west wall and connected to the foundation are 11 strands of 6.35-centimetre (2.5-inch) rods screwed together in 12.1-metre (40-ft.) lengths. They’re compressed to deal with the tension loads in a way that project architect Vance Harris from DIALOG compared with the taut strings of a violin. The rods are estimated to be about three times stronger than standard rebar of similar size.
On the north side are a series of walking columns of varying widths that are offset rather than on top of one another. They start as a single column that, as Poh said, “branches and grows out like a tree into five separate columns when you get to the roof.”
Glotman Simpson has tested Vancouver House under extreme scenarios using advanced computer simulations. The building withstood double the expected maximum quake.
“This is what I’ve been telling all the tours that visited the site and the design team,” Poh said. “This building is arguably the most robust in Vancouver in an earthquake.”

Vancouver House

• 156.9-metre (515-feet) highrise tower (including parapet), 60 floors above grade.
• Triangular lowest floor of 725 square metres (7,800 square feet) expanding to rectangular top floor of 1,226 sq. m (13,200 sq. ft.)
• 30-metre (98-ft.) safety setback from the Granville Street Bridge on ramp.
• Beneath the seven-storey underground parkade is a 4,000-cubic-metre foundation weighing 9,600 tonnes, the equivalent of about 4,266 Model S Teslas.
• 11 strands of 6.35-centimetre (2.5-inch) diameter, high-strength, vertical, post-tensioned rods stretching 112.7 metre (370 ft.) up the west wall.
• In addition to the main tower, there are two low-rise buildings, angled to allow light to the outdoor room they create under the Granville bridge. They connect to the bridge by pedestrian walkways. A spinning chandelier public art work by Rodney Graham will be installed under the bridge.
• In 2015, Vancouver House won the Future Project of the Year at the World Architectural Festival.
— Sources include Glotman Simpson

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