The Engineering Behind a One-of-a-Kind Dubai Megastructure
Dubai’s economy was built on oil profits, but 1991 estimates revealed that their crude supply would dry up by 2016. As it turned out, this was inaccurate, but Dubai’s oil production was at its peak in 1991 and has declined steadily ever since.
However, in light of the looming economic predicament, the Prince of Dubai H.H. Sheikh Mohammed came up with a plan to save the economy.
He turned to Dubai's other natural resources such as sun, sand, and sea to develop a new revenue stream for his country. His solution: the tallest, most luxurious hotel ever made tailored to high-class clients.
Construction began on the Burj Al Arab in 1994. Engineers and Architects will battle against time, nature, and each other to make this dream a reality. Find out how they worked together to tackle some of the most challenging problems with building this one of a kind structure.
The Building’s Iconic Design
Architect Tom Wright wanted to design this building to be iconic and came up with a brilliant solution. If you think about famous buildings and how they stand out, you think about their iconic shape.
We recognize iconic structures such as the Eiffel Tower and the Sydney Opera House by their unique shapes. If you draw a few simple lines, we can see that shape and instantly know what it is. Wright wanted to create this for his client.
When thinking of Dubai and what makes it unique, Wright thought about the sailboats in the sea around Dubai. In his design, he wanted to create an iconic shape of a ship’s sail—a shape reminiscent of the sea and how sailing is a massive part of Dubai culture.
Using the shape of a sail for this massive structure was enormously challenging. Wright wanted it to appear as if a sail was rising out of the sea. However, to create this impression, the hotel would need to be built on an island.
Dubai had no islands, so they would have to decide whether to build it on the shore or build a man-made island to support the hotel. Building the hotel on a man-made island would be far more expensive and posed many additional risks.
Wright and his team weighed both options and the risks involved with each, but ultimately the client chose to build a man-made island to house the hotel.
An Artificial Island with Severe Weather Conditions
Building an enormous structure like the Burj Al Arab on a man-made island presented some unique challenges. The architects and engineers had to work together to ensure the structure's soundness and everyone's safety.
The architects had planned for many severe weather patterns associated with the Arab Gulf, but project architect Simon Crispe was made acutely aware of the dangers when he witnessed a barge containing 10,000 tons of rock slam into the shore during a shumal. He realized they had underestimated the power of the Arabian Gulf.
They had to come up with a solution to keep the weather from damaging the island. At first glance, an island of rock seemed like the best solution. It would be sturdy, and the materials are plentiful and easy to get locally, but Wright rejects this idea. His design calls for a low-profile island, and an island made of rocks would have to be far too large to safely repel the sea.
Waves associated with severe weather are a big issue for the low profile island that Wright had in mind. Mike McNicholas, the island engineer, thought of a solution to solve the problem with the waves and keep the island as low profile as possible.
He suggests they use experimental hexagonal concrete blocks designed to reduce the impact of waves. A layer of these blocks on top of the rock should dissipate the waves. The problem is no one in the area had ever used blocks like this before.
Before they decided to use these blocks, they had to run tests to see if they would work safely. Over the next three weeks, they tested the design using simulations of the highest possible waves projected for the next hundred years. They concluded the blocks are effective and would be safe to use.
They covered their island of rock in a concrete armor made of these hollowed-out hexagonal structures that act like a sponge, sucking in the water and circling it around and considerably dissipating the waves’ force.
Sea Wall Flooding the Structure
Now that they have solved the issue with waves potentially damaging the island, they face a new problem in the next phase of construction, the sea wall. The sea places a massive amount of pressure onto the sand pushing its way underneath the island.
McNicholas plans to build a cofferdam as the base of the structure. He builds this cofferdam using 20-meter lengths of steel placed in a triangular shape. However, digging the sand out of here poses a high risk of the sea wall flooding the structure and potentially killing hundreds of workers.
He decides to inject a layer of concrete from the sides towards the center to form a thick layer to prevent flooding as the sand is removed. The cement seal should keep the pressure caused by the sea wall level and prevent it from flooding. The problem is that as more sand is removed, there is less weight to hold back the sea's force.
McNicholas’ calculations proved to be correct. The concrete layer was sufficient enough to prevent the sea wall from flooding the structure.
A Solid Foundation on Sand
In November 1995, they moved on to the foundation. Ideally, in order to build a solid foundation, they need a layer of bedrock to provide a stable base. Unfortunately, after taking many core samples, they discover there is no bedrock, only sand.
They decided to sink steel-reinforced concrete foundation piles deep into the sand. This method relies on the principle of skin friction, which stops the two rough surfaces from slipping past each other.
They send off samples of sand in containers for testing to ensure that the sand’s density around the pillars will be sufficient to prevent the piles from moving. If it is too loose, it could cause the structure to fail.
High Winds & Earthquakes
The foundation is near a fault line, which means that earthquakes could pose a catastrophic problem. Like the massive earthquake in June of 1964 of Niigata, Japan, liquefaction in sandy soil is a major issue.
As the sand shakes, it loosens up any air pockets and compresses the sand causing it to move like a liquid. In Japan, this caused entire apartment buildings to flip over. This would be a serious issue to consider in Dubai, as well.
The samples of sand sent off for testing showed that they were in luck. Deep beneath the surface, tests showed they had a compacted, calcified type of sand that would be dense enough for the skin friction to work.
They constructed 250 concrete piles that were over 20% longer than initially planned to ensure that liquefaction would not be a problem. These piles had a combined length of 10km, which is 35 times the height of the tower they will support.
The Desert Heat & Steel
Now it’s time to build the structure. The slender frame is not capable of withstanding the elements alone. Wright designed a sort of exoskeleton that used diagonal trusses to connect two steel bows to the building's concrete core.
Unfortunately, these steel trusses caused some issues. Steel expands in heat and contracts in the cold. Dubai had a temperature variance of 14 degrees. This meant that the steel trusses could expand up to 5cm.
The solution was a fixing bracket with an offset center hole that would rotate to line up with the truss's hole location.
They brought in specialist lifting gear from Singapore to place these enormous diagonal trusses as single pieces and position them on the building's exoskeleton. Once the holes are lined up, a steel pin is placed, securing the truss in the correct position despite the 5cm variance.
Vibrations from Vortex Shedding
A uniquely shaped structure this big poses other problems such as vortex shedding. Vortex shedding happens when the wind blows across edges of structures and causes a miniature tornado effect, which in turn causes dangerous vibrations. Those vibrations ultimately cause the structure to fall apart over time.
Volker Buttgereit, the aerodynamicist, performed a wind-tunnel test with a 1:50 scale model. He determined the easiest solution would be to remove the exoskeleton. However, the exoskeleton is what makes the building unique, so this wasn’t an option.
The solution was to install tuned mass dampers in vulnerable points of the exoskeleton to offset the vibrations. As the wind blows and starts causing vortex shedding, the 5-ton weight moves to damp down the vibrations to well within the safety limits. They installed 11 of these dampers along the exoskeleton, effectively canceling out the threat of vortex shedding.
A Restaurant that’s Suspended in the Sky
Wright's design included a winglike restaurant in the back of the structure that floated high above the sea with no visible supports. He wanted guests to feel like they were dining in the sky. This posed a problem for Anthony McCarter, structural engineer, to solve.
The solution was to embed steel brackets in the concrete core and attach steel girders to the brackets. The steel beams protrude outward to serve as a base for the steel floor of the restaurant. They built in the restaurant then encased it in aluminum and glass to finish off the overall design.
With the base of the sturdily embedded into the concrete core at the back of the building, this structure is able to withstand wind speeds close to 160kph.
Battling Humidity & Scorching Temps
Time was getting short. To finish the hotel on schedule, they decided to start on interior decoration before the exterior was completed. This posed a new problem as humidity in the area can be as high as 100% along with scorching temperatures. High temperatures and moisture prevented them from finishing some things. These conditions won't allow the team to put in sensitive finishes like gold leaf, silk, and carved wood. They would have simply fallen apart.
Due to the delicate nature of many of these high-end materials, they first needed to climate-control the interior. First, they enclosed the building by installing the iconic fabric sail wall. The fabric's reflective properties of the sail help keep the temperatures down.
However, construction is still ongoing, and they need a way to get the trucks in and out of the building without letting in the desert heat. They accomplish this by installing an airlock big enough to allow trucks in and out of the building. They have successfully solved extreme temperatures and humidity issues, but now they have a new problem, condensation.
Dealing With Damaging Condensation
Instillation of the massive sail wall formed a large atrium. They had to be careful to introduce air conditioning slowly. The warm air within the atrium could have made a small rain cloud at the top of the building if they lowered the temperature too rapidly. They knew this would cause significant damage to the interior if left unchecked.
The only way to prevent this cost them valuable time. They turned the building’s cooling system on, lowering the temperature very slowly, less than one degree a day. It took six months to cool the building down to the appropriate temperature.
Finally, the interior decoration could really begin. Khuan Chew, who had previously worked with the Sultan of Brunei, was chosen to be the interior designer for this project. She had to create and implement a design that the Sheik would find worthy and to meet the deadline, she had to do it within a short two-year period.
Electricity Demands & Harmonic Distortion
As the building was nearing completion, the Sheik decided he wanted every possible electronic device available for his guests. This new directive rendered the planned electrical system obsolete overnight.
Electrical Engineer Rob Ruse had to redesign the whole system to handle the significantly increased electricity demands, and he had to prevent harmonic distortion. All these electronics can disrupt the waveform of the electric current, causing the problem of harmonic distortion. This can melt the protective sheathing around live cables and cause a disastrous fire.
Ruse creates a groundbreaking harmonic filter system. The system detects harmonic distortion and then sends a current that is the mirror image of the distortion to cancel it. This is called mirror phase and works like noise-canceling headphones to cancel out the harmonic distortion.
To ensure his system works as intended, he installs these systems on all key floors and where electricity enters the building.
The Burj Al Arab made history with it’s innovation. That innovation mixed with the dreams of a very ambitious client paved the way for even further engineering accomplishments. In the years that followed building the Burj Al Arab the construction of the Palm Islands called Palm Jumeirah, Deira Island and Palm Jebel Ali.
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