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This building—the Burj Khalifa—which stands strong on loose, sandy soil braving the strong Arabian winds—is truly a modern engineering marvel. In this video, we are going to explore all the design secrets of the world’s tallest building, starting from its surprisingly simple hexagonal core. This incredible feat of civil engineering is even able to confuse the wind due to its unique shape and lightning with the help of modern technology. Let’s get into it.
The soul of the Burj Khalifa is its hexagonal core. This RCC-built core is the ultimate hero, enabling the Burj Khalifa to keep standing despite the devastating wind storms of Dubai, and helps keep the weight of the building balanced. The hub also accommodates the entire lift system of this building.
Such a slender core is highly unstable; in theory, it could fall at any time. But Skidmore, the company that designed Burj Khalifa, came up with an innovative solution. They took inspiration from the buttresses we normally see on dams to hold the core of the wall and used similar supports around the core. To make the towers around the buttresses practical, they infused a step shape design to the buttresses. We know buildings are always vertical, they are never inclined, right? Here is the main twist. The Skidmore engineers designed the buttresses so that you can actually live next to them without even realizing they are buttresses. The architects of the Burj Khalifa also efficiently used this space for corridors, so from the lift, people walk to their flats between the buttress walls.
The architects, then, designed huge glass facades around the buttresses, giving all the hotels and living spaces inside the facades a breath-taking view from all sides. The support needed for these glass facades came from these cross walls and columns. The main function of the cross wall is not to support the facades. To understand it let’s check out an example. There’s a sandstorm in Dubai, but no cross walls.
Consider the situation. The forces of resistance coming from the buttresses on the opposite side save the building from toppling over. On the left-hand side, the force of the wind is resisted by the combined effect of both these buttresses, which are at an angle. However, such a slender building and a huge force from the heavy sandstorm will obviously lead to the whole building structure bending too much.
Now, we need to understand a notorious property of concrete — its weakness against tensile stress. When a concrete block bends, tensile stress is caused in the outer section of the block. Concrete can only withstand a small amount of tensile stress and it will form cracks easily if the tensile stress continues.
That’s why the hexagonal core has steel bars inside it. The steel bars absorb most of the tensile stress. However, if the core bends too much, the concrete section of the core won’t be able to deal with the tensile stress.
The best method to prevent a cantilever beam bending in structural engineering is by using an I-shaped section. That’s exactly what we’re doing when we connect the cross walls to the buttresses. If you observe carefully you can see the shape has now become like an I cross-section. The entire building is now structurally strong and can withstand the tensile stress without bending.
Can you see some black stripes on the original Burj Khalifa design? They're mechanical floors. If you want to understand their importance, have a look at this diagram. It shows all the columns used in the Burj Khalifa. It’s a complex jungle. These columns have good stability when they are connected to the floors as shown; we know the floors are already strong since they are connected to the core. The mechanical roofs are also used to house electrical and air refrigeration systems, water tanks that bring the Burj Khalifa to life. Nobody stays on those roofs. These floors have a different appearance because they are covered with concrete walls and pipes which are used by the workers so they can grip onto them when cleaning the glass façade.
The interesting thing is that only around 70% of the Burj Khalifa is supported by the concrete core. The top 25% does not have any concrete core support. It is a steel structure. Although the Burj Khalifa mainly resists bending, the top of this superstructure is allowed to bend and sway by about six feet in windy storms. I know, it sounds like a lot! The steel can easily resist tensile loads. So if you experience an oscillation like an earthquake, don’t panic, it’s probably the Burj Khalifa swiftly saying hello to the winds.
Thanks to the reinforced concrete, the hexagonal core is able to withstand the torsion, that is the twist and shear stress, caused by the wind. This amazing buttressed core system is why the Burj Khalifa is also known as a stiffened rod in the face of the wind.
Our design approach has resulted in a Burj Khalifa that looks like this. However, the real Burj Khalifa looks like this. An asymmetrical structure instead of symmetrical. Why did the designers of this marvelous structure go for the asymmetrical design?
The soul of the Burj Khalifa is its hexagonal core. This RCC-built core is the ultimate hero, enabling the Burj Khalifa to keep standing despite the devastating wind storms of Dubai, and helps keep the weight of the building balanced. The hub also accommodates the entire lift system of this building.
Such a slender core is highly unstable; in theory, it could fall at any time. But Skidmore, the company that designed Burj Khalifa, came up with an innovative solution. They took inspiration from the buttresses we normally see on dams to hold the core of the wall and used similar supports around the core. To make the towers around the buttresses practical, they infused a step shape design to the buttresses. We know buildings are always vertical, they are never inclined, right? Here is the main twist. The Skidmore engineers designed the buttresses so that you can actually live next to them without even realizing they are buttresses. The architects of the Burj Khalifa also efficiently used this space for corridors, so from the lift, people walk to their flats between the buttress walls.
The architects, then, designed huge glass facades around the buttresses, giving all the hotels and living spaces inside the facades a breath-taking view from all sides. The support needed for these glass facades came from these cross walls and columns. The main function of the cross wall is not to support the facades. To understand it let’s check out an example. There’s a sandstorm in Dubai, but no cross walls.
Consider the situation. The forces of resistance coming from the buttresses on the opposite side save the building from toppling over. On the left-hand side, the force of the wind is resisted by the combined effect of both these buttresses, which are at an angle. However, such a slender building and a huge force from the heavy sandstorm will obviously lead to the whole building structure bending too much.
Now, we need to understand a notorious property of concrete — its weakness against tensile stress. When a concrete block bends, tensile stress is caused in the outer section of the block. Concrete can only withstand a small amount of tensile stress and it will form cracks easily if the tensile stress continues.
That’s why the hexagonal core has steel bars inside it. The steel bars absorb most of the tensile stress. However, if the core bends too much, the concrete section of the core won’t be able to deal with the tensile stress.
The best method to prevent a cantilever beam bending in structural engineering is by using an I-shaped section. That’s exactly what we’re doing when we connect the cross walls to the buttresses. If you observe carefully you can see the shape has now become like an I cross-section. The entire building is now structurally strong and can withstand the tensile stress without bending.
Can you see some black stripes on the original Burj Khalifa design? They're mechanical floors. If you want to understand their importance, have a look at this diagram. It shows all the columns used in the Burj Khalifa. It’s a complex jungle. These columns have good stability when they are connected to the floors as shown; we know the floors are already strong since they are connected to the core. The mechanical roofs are also used to house electrical and air refrigeration systems, water tanks that bring the Burj Khalifa to life. Nobody stays on those roofs. These floors have a different appearance because they are covered with concrete walls and pipes which are used by the workers so they can grip onto them when cleaning the glass façade.
The interesting thing is that only around 70% of the Burj Khalifa is supported by the concrete core. The top 25% does not have any concrete core support. It is a steel structure. Although the Burj Khalifa mainly resists bending, the top of this superstructure is allowed to bend and sway by about six feet in windy storms. I know, it sounds like a lot! The steel can easily resist tensile loads. So if you experience an oscillation like an earthquake, don’t panic, it’s probably the Burj Khalifa swiftly saying hello to the winds.
Thanks to the reinforced concrete, the hexagonal core is able to withstand the torsion, that is the twist and shear stress, caused by the wind. This amazing buttressed core system is why the Burj Khalifa is also known as a stiffened rod in the face of the wind.
Our design approach has resulted in a Burj Khalifa that looks like this. However, the real Burj Khalifa looks like this. An asymmetrical structure instead of symmetrical. Why did the designers of this marvelous structure go for the asymmetrical design?
When the wind passes around a structure it can lead to a very beautiful and dangerous fluid mechanics phenomenon called vortex shedding. The way they dance looks interesting, right? However, it’s dangerous because the vortices are fluctuating, generating a fluctuating force on the building. If the natural frequency of vibration of this building is the same as the frequency of these fluctuations in force, the building will violently oscillate like this: a phenomenon called resonance. These oscillations will keep on increasing and could eventually make the Burj Khalifa fail completely.
To overcome this issue, SOM, who designed the Burj Khalifa, came up with an architectural innovation. Bill Baker and his team’s idea to break the vortex shedding was to create a spiral in the Burj Khalifa. A spiral shape is the best solution to kill vortex shedding; it just confuses the wind, as the shape varies. Can you find a hidden spiral in this building structure? To discover the hidden spiral in the Burj Khalifa, consider these simple towers with varying heights but many petals. You can clearly see the spiral now. If you observe the Burj Khalifa you can see it also has been constructed using the same technique: towers of varying heights forming a discrete spiral.
Bill Baker used one more spiral version for the top of the Burj Khalifa. He specified varying angles for the tiers. At this height, this dense spiral helps to fight against tip vortex shedding.
These innovations are the reason the Burj Khalifa has successfully reached 830 meters, even though initially it was only designed to reach 518 meters. An additional 312 m — that’s almost as tall as the Eiffel tower — was added during construction. What a marvelous achievement for Dubai!
But how is such a heavy structure able to stand on the loose sandy soil of Arabia without sinking? The engineers of this building couldn’t find any hard strata in this area even after going 140 meters down. These sedimentary rocks are also less strong. So the engineers were faced with two challenges: one was the poor load-bearing capacity of the ground and the second was the differential settlement of the structure.
To tackle these problems, they used a raft that is attached to the hexagonal core, I sections, and columns. The raft was made of a slab of thick, high-performance RCC structure. This raft distributes the weight of the building onto a larger area of sand equally, and thus resists differential settlement. However,how will the weak sand and rocks bear such a huge mass? This raft will just sink. Bill Baker came up with a solution: using multiple RCC piles. The friction between the surface of these piles and the weak-but-stiff sedimentary rocks will resist the load of the building.
Did you notice the beautiful flower-like petals just above the foundation of the building? This structural design, especially these petals, was inspired by one of Dubai’s most widely cultivated flowers: the spider lily.
These lightning strikes on the Burj Khalifa are fascinating but alarming! At the very top of this building, this small, peculiar device is what keeps the Burj Khalifa from burning up. It is a lightning arrester. The dome is connected to a sensor equipment which is connected by a tiny battery. As soon as it detects a super-charged cloud nearby, the arrester immediately generates opposite charges on its surface to attract the lightning towards it. The electron flow of lightning is then passed through the outer column’s steel structure and dissipated into the earth pits via the steel inside the foundation piles. The electrons travel only through the external columns due to the skin effect. Burj Khalifa is Dubai’s lighting rod. Its lightning arrester collects the lightning strikes of almost the entire Dubai thanks to its great height.
Time for the most interesting part: how did they lift the concrete to this height? Due to Dubai's warm weather even if they had used the most powerful pumps, the concrete would have solidified before reaching the destination. Instead, the team used a special grade of concrete named C50 and C80, mixed with cold ice as they pumped it up. This work of pouring the concrete into molds was done at night and would immediately set. The team completed one floor every week; the entire project took six years to complete.
You may be thinking.. is it possible for another building to overtake the height of Burj Khalifa? As a building gets taller, the design challenges we saw in this video also increase. If the engineers are smart enough to overcome these challenges, they can achieve even a taller building. It’s no easy task though!
Now that you have understood the amazing details that keep this megastructure, the Burj Khalifa, standing tall, let's take a tour inside this building.
To overcome this issue, SOM, who designed the Burj Khalifa, came up with an architectural innovation. Bill Baker and his team’s idea to break the vortex shedding was to create a spiral in the Burj Khalifa. A spiral shape is the best solution to kill vortex shedding; it just confuses the wind, as the shape varies. Can you find a hidden spiral in this building structure? To discover the hidden spiral in the Burj Khalifa, consider these simple towers with varying heights but many petals. You can clearly see the spiral now. If you observe the Burj Khalifa you can see it also has been constructed using the same technique: towers of varying heights forming a discrete spiral.
Bill Baker used one more spiral version for the top of the Burj Khalifa. He specified varying angles for the tiers. At this height, this dense spiral helps to fight against tip vortex shedding.
These innovations are the reason the Burj Khalifa has successfully reached 830 meters, even though initially it was only designed to reach 518 meters. An additional 312 m — that’s almost as tall as the Eiffel tower — was added during construction. What a marvelous achievement for Dubai!
But how is such a heavy structure able to stand on the loose sandy soil of Arabia without sinking? The engineers of this building couldn’t find any hard strata in this area even after going 140 meters down. These sedimentary rocks are also less strong. So the engineers were faced with two challenges: one was the poor load-bearing capacity of the ground and the second was the differential settlement of the structure.
To tackle these problems, they used a raft that is attached to the hexagonal core, I sections, and columns. The raft was made of a slab of thick, high-performance RCC structure. This raft distributes the weight of the building onto a larger area of sand equally, and thus resists differential settlement. However,how will the weak sand and rocks bear such a huge mass? This raft will just sink. Bill Baker came up with a solution: using multiple RCC piles. The friction between the surface of these piles and the weak-but-stiff sedimentary rocks will resist the load of the building.
Did you notice the beautiful flower-like petals just above the foundation of the building? This structural design, especially these petals, was inspired by one of Dubai’s most widely cultivated flowers: the spider lily.
These lightning strikes on the Burj Khalifa are fascinating but alarming! At the very top of this building, this small, peculiar device is what keeps the Burj Khalifa from burning up. It is a lightning arrester. The dome is connected to a sensor equipment which is connected by a tiny battery. As soon as it detects a super-charged cloud nearby, the arrester immediately generates opposite charges on its surface to attract the lightning towards it. The electron flow of lightning is then passed through the outer column’s steel structure and dissipated into the earth pits via the steel inside the foundation piles. The electrons travel only through the external columns due to the skin effect. Burj Khalifa is Dubai’s lighting rod. Its lightning arrester collects the lightning strikes of almost the entire Dubai thanks to its great height.
Time for the most interesting part: how did they lift the concrete to this height? Due to Dubai's warm weather even if they had used the most powerful pumps, the concrete would have solidified before reaching the destination. Instead, the team used a special grade of concrete named C50 and C80, mixed with cold ice as they pumped it up. This work of pouring the concrete into molds was done at night and would immediately set. The team completed one floor every week; the entire project took six years to complete.
You may be thinking.. is it possible for another building to overtake the height of Burj Khalifa? As a building gets taller, the design challenges we saw in this video also increase. If the engineers are smart enough to overcome these challenges, they can achieve even a taller building. It’s no easy task though!
Now that you have understood the amazing details that keep this megastructure, the Burj Khalifa, standing tall, let's take a tour inside this building.