The Burj Khalifa in Dubai is the tallest building in the world and a marvel of modern construction and engineering. Completed in 2010, the towering edifice reaches a total height of 2,717 feet and is a sharp contrast against the relatively flat landscape around it.
Building such an immense structure posed several unique challenges that almost no other building project anywhere on the planet has encountered. Significant engineering problems needed to be addressed to ensure the tower could safely support itself and provide a safe residence for those within.
In this article, we’ll look at some of the unique challenges faced during the development of this gargantuan building and what innovative (and sometimes simple) fixes were applied.
Architectural Design
The most obvious engineering challenge presented by such a large tower is its architectural design. Rising high above Dubai, the building needed to be designed to withstand huge wind gusts yet remain aesthetically pleasing. Aside from wind, the building also needed to compete with the harsh high temperatures that the region is known for.
One of the first design considerations was the building’s shape, which needed to be incredibly strong and aerodynamic enough to withstand wind. Inspired by a regional desert flower, the tower’s unique Y-shape was chosen.
This shape enabled construction around a central core, which provides immense strength and stability to the build. The core, shaped like a hexagon, provides a spine in which essential services and transportation can be housed. In addition, the central spine allows for a tiered build, with each arm of the Y-shape receding slightly as the building moves up.
Using unique architectural designs married to this shape, the building was engineered to ‘confuse’ wind shears as they approached it. This concept, which underwent extensive testing in wind tunnels, was proven to break wind vortices that could otherwise place structural stress on the building.
Foundations
Once the massive tower’s design was finalized, the next engineering hurdle was anchoring it safely to the ground. In many cases, foundations for tall buildings can be built into the solid bedrock below building sites. However, Dubai is predominantly a desert, so the site offered little rock below the surface.
After conducting immense geotechnical research and investigations of the building site, engineers found a layered subsurface that posed more challenges than expected. Unexpected levels of subsurface water, many with high salinity, were found, which could cause corrosion of foundations and steel reinforcements.
Engineers decided to use a unique pile foundation system to combat the challenging ground conditions. This system, which required 192 piles bored up to 165 feet into the earth, created a strong base to distribute the tower’s weight evenly.
Atop these piles, a concrete slab measuring just over 12 feet and covering an area of more than 26,000 square feet was poured. This slab, set atop each pile, which measures almost five feet in diameter, solved the problem of anchoring the building. However, the composition of each pile (and the rest of the building) posed yet another engineering challenge.
Concrete Mix
Due to the subsurface water present on the construction site, engineers could not use regular high-strength concrete for the Burj Khalifa. Instead, a unique, specialized mix was designed to withstand the aggressive underground conditions.
This mix was required not only for the foundation piles to withstand chemically aggressive subsurface water but also for the construction of the building, as regular concrete could not be pumped high enough for building purposes.
As such, the final concrete used was specially designed to have a high density, offer low permeability, and flow easily. Together, this mix resulted in super strong concrete that could be pumped to the top of the immense structure using huge pumps.
The final challenge in confirming the concrete mix was the curing process after it was poured. Due to the extreme temperatures in the region, the curing process needed to be slowed enough to allow the mix to be pumped and cast before hardening. To combat this, engineers used a straightforward solution: ice.
When ice was mixed into the concrete, the temperature dropped significantly enough to allow the mix to be properly pumped and cast before curing began.
Logistics
The final major hurdle in the construction of the Burj Khalifa was the movement of people and materials to various sections of the massive vertical city. This was essential for the 17 million people visiting the tower each year and the construction teams building it.
With 12,000 workers building the tower, who had little time to enjoy things like exploring the city or finding the list of the best social casinos online, engineers needed a quick way to get from the base of the tower up to the top—163 floors above the ground.
To do this, they devised double-deck elevators, each capable of holding up to 14 people per deck. These elevators run in a pressurized environment, which helps them operate more efficiently and counteract the difference in temperature between the various sections of the building.
More than simply holding enough people, these elevators needed to be quick, as a trip up 163 stories could take substantial time. The high-speed elevators travel up to almost 33 feet per second to mitigate this.
These elevators were staggered and terminated at various sky decks, with floors cordoned off specifically to allow workers and residents to change to a different elevator.
Conclusion
During construction, the developers of the world’s tallest tower faced many other engineering hurdles. These included cladding the building to withstand the desert heat, installing cooling systems, and pumping water to the top of the building.
The completed building, glistening in the hot United Arab Emirates sun, is a testament to the determination of everyone involved in the process. The unique engineering techniques used have also allowed other ambitious builds to be undertaken with a firm knowledge of how to do things many think impossible.
<p>The post The Engineering Miracles Behind Burj Khalifa first appeared on CCR-Mag.com.</p>