Deep Pile Contractors Excel at Aldhar HQ August 12, 2010

Deep pile contractors and building engineers are continually pushing the limits of commercial construction capabilities through their aggressively unique projects.  The Aldar HQ building in Abu Dhabi is a coin shaped building that combined both an unbelievably aggressive timeline and a foundation that had no previous benchmarks to follow. 

Engineers called the building process a "leap of faith" with construction being one step ahead of the blueprints development due to the unprecedented timeline.  The project's ownership wished to have the building completed so that it could be gazed upon and toured by the masses that were predicted to be present during the city's inaugural grand prix event; which was less than 30 months from the time that the designers felt comfortable about the blueprints. 

Due to its circular design (a round disc on its edge) the building has a narrow base in context with the wide edges.  This created a difficulty in the foundation's design.  High force winds are present in the area which puts stress on the foundation elements.  The most prominent winds in the region are gusty winds that are the result of thunderstorms.  The intense sun heats the moist air in the spring causing these storms that can result in winds of up to 85 miles per hour.  Experts who understand the area have learned that thunderstorms create winds that are the strongest between 160-490 feet above ground.  The design of the Aldar HQ puts most of the structure in this zone.

The aggressive timeline did not permit enough time to perform proper wind tunnel tests before work on the foundation began.  To gather accurate data as it relates to wind impact, wind engineers built a scale replica of the entire city.  This gave them insight into how winds moved across the landscape, and more importantly, how the winds would impact the structure of the project.  Engineers anticipated that the wind would result in a force that wishes to "twist" the structure.  Wind test engineers were delighted to convey the information that their studies confirmed that the structure would be able to withstand the expected gusty winds.

To prepare the foundation crews had to build a diaphragm wall made of interlocking concrete panels that they could "socket" into the bedrock.  Upward pressure of water and loose sand created a challenge that was addressed by the construction of a diaphragm wall.  This wall (also known as a "D-wall") is a variation of a cofferdam that is used to hold back water and sand so that the foundation area can be excavated.  All material inside of the wall was removed.

400 concrete piles were used.  Half of the piles rely on friction to the ground to secure the structure to the rock and sand below.  The other half of the piles was driven into the rock to dissipate the immense loads in to the ground.
The circular building required a core skeleton on which the 65,000 tons of weight would rest.  Engineers designed a dual core system made of steel and concrete to support the weight.  The twin spines rose 410 feet from the slab, and the concrete had to be cast in place without any flaws that resulted in two individual columns being constructed.  The challenge was met with a "slip form" approach.  The method is executed by pouring liquid concrete into a giant form that progresses up the spine as it is cast; each casting becomes the foundation for the next pour.  A "diagrid" made of steel provided the exoskeleton on which the external of the project is housed.  99 "A-frame" panels each weighing near 30 tons were required to complete the framework.  

The intelligence of deep pile engineers and the critical equipment that exists in today's marketplace result in the ability to convert a design into a fascinatingly ornate commercial "work of art."
Savvy commercial foundation contractors can provide insight and practical solutions resulting from their ability to draw on years of experience in a wide variety of similar situations.  Foundation Contractors was founded in 1971 in Northern California and provides unparalleled expertise on complex foundation projects.
 

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