This is the Burj Khalifa. The tallest building on earth.
Rising 828 metres into the sky, nothing else has really ever come close to topping it.
But that was all supposed to change. Enter Jeddah Tower.
At a staggering 1,000 metres – Saudi Arabia’s $1.2BN megatall skyscraper was
due to become the first-ever kilometre high building in 2020. A tower that would finally
overtake the Burj Khalifa and help position Jeddah as a global city on par with Dubai.
Then things took a turn.
Today the building stands unfinished and abandoned
300 metres in the air – and after years of political crackdowns and a global pandemic,
it’s unclear if Jeddah Tower can ever rise to its full height.
Even if construction works do start up again,
it’ll take a massive feat of engineering to complete.
There are really no building codes that sort of prepare you for it. With over a billion dollars
and to a large extent the country’s reputation riding on the completion of this tower,
all eyes are on Jeddah to see if it can ever complete the world’s tallest building.
Now like any skyscraper, the taller it is – the more attention it tends to get.
Sound bite: Saudi Arabia is looking to make a major push in its economy.
Sound bite: Jeddah Tower - soon to be the tallest building in the world. Once completed
it will reach a height of 1KM. Back in 2011, billionaire investor
Prince Alwaleed Bin Talal had his sights set on creating a centrepiece for Jeddah Economic City.
His bold plan for a skyscraper in – you guessed it – Jeddah – would feature 167 storeys of homes,
offices and hotels. At a kilometre tall it would rise well above the
600-metre threshold for classification in the “megatall” skyscraper category
and would essentially try and make Jeddah the Dubai of Saudi Arabia.
It’s important to draw a distinction between this and the other huge
projects that Saudi Arabia has recently announced, particularly around Neom.
They’re led by its Public Investment Fund, a state-driven sovereign wealth fund that’s seeking
to diversify the Saudi economy away from oil. Jeddah Tower is a private development,
albeit one that started out with plenty of backing from many in the state.
Now to build something a kilometre tall you need an architect with a strong resume.
Enter Adrian Smith – if his name sounds familiar to you, it’s because he’s the
guy who designed the Burj Khalifa. One of the biggest challenges with
designing skyscrapers this high is the extreme lateral wind loads they face.
The taller a building is, the greater its tendency to want to sway towards
its top – and that’s something engineers must address to ensure safety and comfort.
To reduce movement, some supertalls, like Taipei 101 or 432 Park Avenue,
implement massive weighted devices called tuned mass dampers near their summits that
counteract swaying motion, but these can take up a lot of valuable floor space.
For Jeddah Tower, Smith instead took another route; one that lies in the most fundamental
part of the building design itself Like the Burj Khalifa, the Jeddah
Tower plans to use a buttressed core to reach its megatall height.
Unlike most skyscrapers that have four external walls,
a buttressed core sees a hexagonal core reinforced with three Y-shaped walls.
And that really does work. We used software from today’s video sponsor Simscale to model
how wind forces could flow around the Jeddah Tower’s enormous form.
It's kind of analogous to the three legged stool…. John Cetra wasn’t involved in Jeddah Tower,
but he knows a thing or two about the design of extremely tall buildings.
It's a very, very efficient system that the triangle works in ways to deflect
the forces from one or two sides. It doesn't necessarily have the same effect as, let's say,
a square where You know, there's a broadside on the square or a rectangle and those forces
are then deflected to the other three sides. The Jeddah Tower would also dramatically taper
toward its peak, further reinforcing its resistance to strong winds and
making it more aerodynamic than a four-walled straight up profile.
That really matters because winds get stronger the higher you go – and on this site, with a building
of this height, there aren’t any other buildings or structures around to break up the air flow.
On the 157th floor would be the tower's crowning feature: a jaw-dropping open air
observation deck that would easily become the highest viewing platform in the world.
With that design finalised, building works first began back in 2013.
Now as we all know, one of the first steps of construction is also the most important:
foundations – and to support something this tall, engineers needed to use a lot of concrete.
First, 270 piles were drilled to 105 metres into the ground. Then a giant
five metre thick concrete slab was placed on top.
That would become the base distributing
the weight of all 1,000 metres of skyscraper set to rise above it.
Next the core was constructed, allowing the tower to steadily rise around it.
Concrete was poured in a jump-form mould – that’s a type of climbing formwork that rises
with the core structure allowing builders to work safely and with considerable efficiency inside.
Mehdi Jalayerian worked on some of the operational and technological systems within the building.
As far as the building configuration itself what we did, we the challenge that we overcome, we thought
about it as be 20 to 40 story buildings stacked on top of one another. So we broke it
down into smaller pieces to be able to manage it. In 2015, two years after construction began,
the project secured $1.2BN in funding from a Saudi bank and real estate venture.
By 2017, Jeddah Tower had risen 63 storeys above the desert – around ⅓ of its final height.
Despite some bumps in the road and minor delays,
it looked as if the world would soon be getting its next tallest building.
But things took a turn. When Mohammad bin Salman became crown prince of Saudi Arabia – he began
an anti-corruption purge.
Two people caught up in the events included Jeddah Tower’s key backers – businessman Prince
Alwaleed and Bakr Bin Laden – chairman of the tower’s construction company – Binladin Group.
That all caused work on Jeddah Tower to briefly stall.
The project’s backers were eventually released and work briefly restarted, but then there were
labour issues with a contractor that further complicated matters, stalling it again.
Just as construction was about to restart in 2020, the pandemic hit and works halted.
It appears that ever since then the tower has sat empty and incomplete.
Yet take a look at the official website and the homepage still says ‘It’s happening’.
Jeddah Tower was going to be a challenge for engineers on a
good day. Throw in these considerable political and logistical issues and
perhaps little wonder that things have seemingly ground to a halt.
So we’ve seen what it’s supposed
to look like, but even if everything restarted … is it actually even possible to build this
tall? Well the truth is we’ll never know unless it’s actually achieved in physical steel and
concrete. What we can say is that engineers were pretty certain they could do it and built the
core to almost the same height as New York’s Chrysler Building before things got stopped.
They worked from the established principles paved out by other tall buildings and most notably the
Burj Khalifa. They modelled, tested and simulated their designs in a wind tunnel and brought them to life in virtual
software before even putting a spade in ground or attempting to pour concrete above the clouds.
The building’s aerodynamic performance and ability to manage lateral wind loads was put to the test in a wind tunnel
modelled in software similar to that produced by today’s video sponsor Simscale. It allows
engineers to test how different profiles and designs will perform under a range of conditions.
All tall buildings have to manage wind loads and, as we said, it gets harder the higher you go.
When strong winds move around structures, areas of lower speed air – also known as
“separation vortices” – emerge on their opposite side, creating suction forces
that pull at the buildings, putting them at risk of swaying back and forth.
Tapering a building as it rises helps to break up the uniformity that causes this. We ran
a model of the Jeddah Tower through Simscale’s software to show you how effectively this works.
We also created a simulation showing how wind forces could influence the
surrounding area at street level, both with and without the skyscraper. You can see the
completed tower would be likely to produce stronger gusts on the ground near the base,
so designers will need to work to minimise that and protect pedestrians.
Simscale is a powerful cloud-based engineering simulation platform that enables everyone to
create high-fidelity simulation tools for building physics, urban design, and sustainability.
You can model everything from wind conditions to thermal performance, indoor air quality,
and thermal comfort. By running these virtual tests early in the design process teams can
solve problems before construction starts, saving teams time and money.
And for Jeddah Tower, time is money the longer construction is stalled.
To take this concrete core in the desert and turn it into the full height occupied
building will mean running tests to understand the strength and
rigidity of the existing structure before re-commencing construction on top of it.
The building’s structural lifespan calculations are
thrown off by part of it being six years older than the rest.
Once the rest of the structure goes up,
an advanced cladding system needs to follow close behind.
Mechanical systems that can withstand extreme conditions
1,000 metres in the sky then need to be designed and installed.
And it’ll require one of the tallest elevators ever built.
Now, historically skyscrapers this tall have required people to change elevators
on the way up. That’s because, after a certain point – around 500-metres – the
weight of the steel ropes used to lift them becomes too much.
But innovation’s like UltraRope by KONE (that we mentioned in a recent video) replace those
steel ropes with a carbon fibre material that’s seven times lighter and more durable. It means an
elevator can travel up to a kilometre into the sky and The B1M understands that KONE’s system
is specified to be installed at the Jeddah Tower, should the building ever proceed.
​As you might be gathering, the whole extreme height thing really does make
this project tricky. Despite that, some designers are turning it to their benefit.
At those other elevations you have actually higher intensity of solar….For example, the top of the
building has a spire, which is the actual silo.
we had to build in an environment where we could control the temperature so the concrete is not expanding and contracting.
We utilise the temperature variation to
create a stack effect inside the silo to be able to ventilated properly. So it doesn't really use
any energy and is self ventilated
But the Jeddah Tower’s location in the
desert brings more than just intense heat to the table and creates a huge maintenance requirement.
Sand storms are abrasive. SO you can imagine that it's very fine sand, it's swirling around the building
and you want to have durable coatings on the building that would not be sanded away
That also affects the cleanliness of the building. In the ME they use many systems that don't require a human to be on the scaffolding. That's automatic.
Now building something as bold as the world’s
tallest building will bring you headlines … and some jealousy.
You might recall the plans for Dubai Creek Tower, a scheme announced by the UAE to bring
the title of “world’s tallest structure” back to the country that started work and
then paused again after Jeddah Tower hit the buffers. Its foundations remain sitting there,
kind of like a quiet warning to Jeddah should it ever start up again.
Despite the long pause,
Mehdi thinks things could start to move soon. They have built the utilities and roadways
at the site, which was really good, so now I think we're in a much better position. There
is a lot of talk right now and planning to restart. They have built the utilities and roadways at the site.
It's been stopped for a while and there are things that need to be rethought for the process. So now I think we are in a better position
still be possible to turn this supertall stump into the world’s tallest building,
right now the challenges of funding, politics and extreme engineering all appear equally daunting,
collectively putting a heavy block on progress. If the world’s first kilometre high skyscraper
ever rises from these sands it’ll be both record-breaking and remarkable in many ways.
This video was made possible by Simscale, you can learn more about that at the link
below. There’s also the chance to dive deeper on Jeddah Tower and the other topics on our
channel over on The World’s Best Construction Podcast – available now wherever you get
your podcasts. And as always, if you enjoyed this video and you want to get more from the
definitive video channel for construction, make sure you’re subscribed to The B1M.