While the height of buildings remains an unrelenting obsession amongst developers and architects, there is also a growing trend amongst engineers to see how far a building can be cantilevered.
First applied in the sphere of bridge engineering, the steel truss cantilever bridge was considered a major breakthrough as it is capable of spanning distances in excess of 460 metres. Similar principles were soon applied to modern building design with dramatic results.
When speaking of extreme cantilevers, one cannot look past the Busan Cinema Centre in South Korea. Designed by Austria-based architects COOP HIMMELB(L)AU, the complex – comprising cinemas, offices, studios and restaurants – boasts a landmark engineering achievement in its remarkable roof structure.
Known as the Big Roof, it weighs 6,376 tonnes and measures 163 metres in length and 60 metres in width, with an 85-metre-long cantilever section, making it the longest cantilevered roof in the world.
Daesung C.P Engineering built the roof around a grid-like steel girder system. The real challenge, though, was keeping the roof attached to the single hourglass-shaped column that supports it. In order to deal with this issue, builders stiffened the juncture by inserting what they refer to as a steel "crown" inside.
Using the Double Cone as its pillar, the Big Roof stands 165 metres high and supports a facility 21 metres above the ground. The front and back of the Big Roof were completed on the ground level, and were hoisted up on a tower crane before being attached where the Double Cone supports the structure.
Australia’s biggest building cantilever is not just about the dramatic. Although still monumental, the cantilever on One Central Park in Sydney houses a panoramic terrace and a theatrical public artwork, consisting of an innovative system of fixed and motorized mirrored panels.
This ‘heliostat’ will capture sunlight and reflect it down onto the landscaped terraces, extending the central parkland at the heart of the new precinct into the green building.
Extreme cantilevers are also becoming more commonplace on a residential scale, where the results are no less impressive.
Pittsburgh architect Eric Fisher has an undergraduate engineering degree. His clients had a vision for an old-time foreman’s shack perched on a warehouse roof and wanted to build their home above their glass factory workplace.
Fisher’s initial analysis showed that code and structural restrictions would not permit this, so instead he proposed cantilevering a pair of massive trusses more than 50 feet over the warehouse from a concrete block base garage that would be located to the rear.
Situated beneath this is a pier which is driven 100 feet below grade to support the gravity load, four-inch-diameter rods then hold it in tension and prevent it from pulling away from the slope.
Despite the initial misgivings of his client, the Emerald Art Glass Home has become what Fisher believes to be the world’s longest cantilevered home.
For sheer audacity, there is Mauro Turin Architectes' wine museum in Lavaux, Switzerland.
They envision cantilevering the museum from the side of a mountain overlooking the historic vineyards, some of which date back to the 11th century. Visitors will walk along a glass and steel walkway jutting from a rock in the mountainside, with glass sides creating unbroken views over the vineyards and out to Lake Geneva.
The project was awarded after the design won a competition last year but there is no further word on its progress. No doubt some engineers in Europe are suffering from numerous sleepless nights.