The scale and ambition of skyscrapers lead many of us to view them
as permanent fixtures on our city skylines.
But for all their size and presence
但是 尽管它们体型庞大 存在感强烈
these huge structures are in fact just as replaceable
as anything else we built.
So what do you do with buildings this big
when they reach the end of their lives?
How do you demolish them in the middle of
such heavily developed and densely populated areas?
only a handful of towers taller than 150 metres
have ever been intentionally destroyed.
The process is highly complex, specialist
and fraught with challenges.
In a world that is constructing more tall buildings than ever before
and with several structures now slated for demolition
to make way for even larger towers.
This is how to dispose of a skyscraper.
Skyscrapers are a highly effective way of
creating space in dense city centres
but with life-spans ranging from 50-100 years,
many no longer provide the right type of space needed in a modern metropolis.
Now, an increasing number of tall buildings around the world
are being earmarked for demolition,
clearing the way for even larger developments.
In New York City, the 216-metre 270 Park Avenue recently
became the tallest skyscraper ever to be intentionally demolished,
making way for JPMorgan Chase’s new 70 storey structure.
When we think about the demolition of a building
many of us imagine wrecking balls and dramatic implosions.
But while these methods may be the quickest way to destroy large structures
– like stadiums or casinos
their use within built-up, heavily populated areas is challenging
and the effects of noise, dust, citizen safety
and proximity to other built assets prohibits their use.
Rather than coming down in a matter of seconds,
the removal of a skyscraper is in fact a carefully planned process
that is carried out piece-by-piece,
much like the construction of the building, but in reverse.
It’s perhaps easier to think of the process as “deconstruction”
rather than “demolition”.
While skyscraper disposal can take a few different forms,
the primary method sees contractors and engineers
start from the top of a structure and work their way down.
Once the relevant demolition plans and permits are approved,
contractors must first contain and remove any harmful materials or substances
such as asbestos
to avoid contaminating the surrounding area.
With internal strip-out works underway,
the building becomes enclosed in scaffolding and netting
to minimise the impact of noise, dust and debris
on the public and neighbouring properties.
While this can take the form of a complete enclosure
like that which went up around Sydney’s 188-metre AMP Tower
during its partial demolition in 2019.
The sheer scale of 270 Park Avenue
sees the disposal process broken-up into four phases.
Levels 16, 29 and 41 of the structure have been stripped-out
and modified into bracing floors,
supporting the scaffolding for each section of the tower above.
As each section is fully enclosed, internal fixtures, services,
and eventually the building’s windows are removed
leaving only the concrete and steel superstructure remaining.
This process is repeated for each section of the tower.
The method of moving waste material
from the top of the building down to street level
varies between disposal projects,
but contractors tend to use chutes and hoists for non-structural wastes,
minimizing the time that cranes are needed on site.
With windows and cladding removed and
the tower stripped to its core superstructure,
small excavators and handheld tools are used to
break-up the concrete floor slabs and steel framing.
This process is steadily repeated level-by-level
until the skyscraper is no more.
Though there are alternatives to this method
such as this “creative demolition” in Japan,
where all work is contained within a hydraulic framework
the principles remain much the same.
While tearing down an entire skyscraper could be seen as wasteful
it’s important to note that landfill costs account for
a large proportion of a demolition contract.
As such, every effort is made to reduce the amount of waste material
that is sent to landfill by reusing and recycling waste as far as possible.
To date, 270 Park Avenue has reportedly
diverted over 90% of its waste away from landfill,
putting it well ahead of LEED’s highest standards set for demolition projects.
The cost and effort required to fully dispose of skyscraper
makes it a significant undertaking
and the process is seen as a last resort amongst developers.
Though more skyscrapers are set to be demolished as urban populations expand,
building adaptation is becoming an increasingly attractive alternative to demolition.
This process sees skyscrapers significantly altered for new uses
while retaining the bulk of their superstructures.
New York City’s Woolworth Building had its upper floors converted to luxury residential apartments
when the tower’s structure prevented it from offering the open-plan offices
that large companies required.
While in Sydney, the redundant AMP Tower will retain over 60% of its original structure
as it is transformed into Quay Quarter Tower,
a 216-metre sustainable skyscraper.
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