While most conventional structures are designed with a clearly defined centre of mass, advancements
in engineering, construction materials and building techniques have allowed some architects
and engineers to conceive a range of awe-inspiring structures that seemingly reject the laws of physics.
Despite each of these schemes appearing unsettling at first, they are in fact as sturdy as any others.
From floating museums that reach into other countries, to breath-taking cantilevered sky
gardens and truly terrifying observation platforms, these structures appear to defy gravity.
Sydney’s One Central Park is a twin tower mixed-use development with a highly unusual exterior.
Not only does the surrounding green space reach up the facade of the two towers - it
also extends far into the sky in the form of the eastern tower’s cantilevered sky garden.
Containing a range of residential amenities - including an outdoor terrace, barbecue facilities
and a plunge pool - the most dynamic feature of this cantilever is a reflective heliostat
featuring 320 motorised mirrors that bring natural light into the space between the two buildings.
Built using a steel truss system, the cantilever and adjoining heliostat extend an incredible
42 metres beyond the footprint of the tower.
While reflectors in the heliostat track the movement of the sun during the day, by night,
an array of LEDs turn the feature into a vibrant light display.
Forming part of the iconic Olympic Stadium for the 1976 summer games, Montreal Tower
was set to support the venue’s retractable roof along with a range of other sporting facilities.
However, despite construction works commencing in 1973, the tower stalled at 92 metres in
height due to design complexities, the weather and strike delays.
It remained unfinished during the Olympics.
Originally planned to be built entirely with concrete, when construction recommenced after
the games it was revealed that the tower would, in fact, be too heavy to support itself if
concrete was used as the primary building material.
In light of this set-back, steel was used to construct the remainder of the tower.
Rising to an overall height of 175 metres, the tower reaches a 45 degree angle making
it the tallest inclined structure in the world.
The building also features an observation
deck, Canada's largest aquatic centre and, following extensive renovations in 2018, commercial
space that will bring over 1,000 people into the tower each day.
Heading south and into the United States, we come to one of the world’s most adrenaline-inducing
structures - the Grand Canyon Skywalk in Arizona.
Cantilevering 20 metres out over the edge of the Grand Canyon, this observation platform
places visitors on a glass walkway above the canyon floor.
Built in conjunction with the native Hualapai Nation, this impressive platform required
considerable engineering to achieve its structural stability.
The platform consists of an inner and outer beam that are anchored to four posts on either
side of the platform.
These are in turn anchored in pairs to four large concrete footings which are themselves
anchored 14 metres into the bedrock using high strength threaded rock anchors.
Additionally, to mitigate any vibration caused by wind and pedestrian loads, two tuned mass
dampers are installed on either end of the platform, while a third damper is positioned
at the platform’s greatest extent from the canyon wall.
Only 120 people are allowed on the platform at any time, despite the structure being engineered
to hold 822 people without overstressing.
Built to commemorate the 50th anniversary of the Timmelsjoch Alpine Road connecting
Austria and Italy through the Tyrolean Alps, this museum cantilevers 16 metres out from
the mountain while effortlessly paying homage to its surroundings.
While it appears to be perched precariously on the edge of a small hill, the mound cleverly
hides the building’s foundations which are buried below ground and act as a counterweight
to the protruding structure above.
The cement used to construct the museum was blended with rocks and pigments from the surrounding
area, allowing the structure to almost merge with its context.
With the region of Tyrol changing hands between the two countries throughout the centuries,
the museum was built on a symbolic site along the pass.
While it’s foundations and entrance lie in North Tyrol - part of Austria - the opposing
panoramic window at the end of the main structure in fact lies in the Italian territory of South Tyrol.
The striking CMG Headquarters in Beijing features one of the largest and heaviest cantilevers
in the world.
Consisting of two inclined towers connected via a skybridge, the cantilevered element
of this structure contains up to 13 storeys at its deepest point that is suspended 162
metres above the ground.
To achieve this remarkable feat of engineering in an active seismic zone, engineers devised
a unique diagrid exoskeleton to carry the structures extreme loads and transfer them
through the superstructure of the building.
Demanding more than 40,000 structural elements, this exoskeleton can be clearly seen on the
exterior of the building.
The irregular pattern of these elements is a response to the varying levels of stress
acting on the structure, with tighter diagonal patterns indicating areas of particular intensity.
With 17,000 tonnes of force acting on some of the building’s columns under normal circumstances,
it was imperative that the steel used in construction was of uniform temperature when the two towers
were connected, minimising any additional stresses that could arise from misaligned
structural members affected by varying changes in temperature.
To ensure this, workers only connected the towers during the early hours of the morning,
before the sun rose.
While each of these structures are in fact firmly secured to the ground, the engineering
and technology that allows them to stand strong while inspiring wonder is a testament to the
capabilities of our incredible industry.
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