Capital Gate, also known as the Leaning Tower of Abu Dhabi, is a skyscraper in Abu Dhabi close to the Abu Dhabi National Exhibition Centre. At 160 meters (524.9 feet), or 35 stories, it is one of the tallest buildings in the city. It was designed to incline 18° west. The owner and developer of Capital Gate is Abu Dhabi National Exhibitions Company. The tower is a focal point of Capital Centre (Abu Dhabi)'s surrounding area.
Video Capital Gate
Construction
Project timeline
- September 2007 - Project started.
- November 2007 - Drilling started foundations.
- April 2008 - Core wall construction started.
- February 2009 - Façade erected.
- May 2009 - The building reached a height of 100 meters.
- June 2009 - Incline started to take shape.
- October 2009 - The building reached its final height of 160 meters.
- December 2009 - Completion of exterior core structure.
- January 2010 - First phase of splash completed.
- February 2010 - Interior construction started.
- March 2010 - Started building the bridge to Abu Dhabi National Exhibition Centre.
- April 2010 - Started building the atrium roof.
- 2011 - Completed construction.
- Dec 21, 2011 -- Opening date.
Foundation
The structure sits above an extensive distribution of 490 pilings that have been drilled 100 feet underground to accommodate gravitational pull and wind forces, as well as seismic pressures caused by the lean of the building. Of the total 490 pilings, 287 are 1 meter (40 inches) in diameter, and 20-30 meters (65-100 feet) deep. The remaining 193 are 600 mm (24 inches) in diameter and 20 meters (65 feet) deep. All 490 piles are capped together using a densely reinforced concrete mat footing nearly 2 meters deep (7 feet). The piles, which were initially in compression during construction to support the lower floors of the building, are now in tension as the stresses caused by the overhang have been applied.[1]
Core of the structure
The core of the Capital Gate was built using jumping formwork, also known as climbing formwork. The center concrete core had to be specially designed to account for the immense forces created by the building's lean. The core, which contains 15,000 cubic meters of concrete, reinforced with 10,000 tons of steel, uses vertical post-tensioning and was constructed with a vertical pre-camber. This pre-camber means the core was constructed with a slight opposite lean. As each floor was installed, the weight of the floors and diagonal grid, or "diagrid" system pulled the core and slowly straightened it out. The core contains 146 vertical steel tendons, each 20 meters (65 feet) long, which are used for post-tensioning.
Superstructure
Given the 18° lean of the 160-meter Capital Gate, construction required two diagrid systems: an external diagrid defining the tower's shape, and an internal diagrid linked to the central core by eight unique pin-jointed structural members. The external diagrid comprises 720 sections of varying shapes, as it is based on the direction in which the tower leans. The external grid carries the weight of the floor while the internal diagrid connects with the external and transfers the load to the core [2], thereby eliminating the need for columns in the floor.
Maps Capital Gate
World record
In June 2010, Guinness World Records certified Capital Gate as the world's "Farthest manmade leaning building". The new record shows that the Capital Gate tower has been built to lean 18° west; more than four times that of the Leaning Tower of Suurhusen. The Guinness World Record was given by a Guinness-appointed awards committee in January 2010, when the exterior was completed.
The gravitational pressure caused by the 18° incline is countered by a technique called pre-cambered core, using a core of concrete reinforced with steel, with the core deliberately built slightly off-center. It is also anchored to the ground by 490 piles which are drilled 20-30 meters underground.
Architecture and design
The building has a diagrid specially designed to absorb and channel the forces created by wind and seismic loading, as well as the gradient of Capital Gate. Capital Gate is one of only a handful of diagrid buildings in the world. Others include London's 30 St Mary Axe (Gherkin), New York's Hearst Tower, and Beijing's National Stadium.
The Capital Gate project was able to achieve its inclination through an engineering technique, known as pre-cambering, that allows floor plates to be stacked vertically up to the 12th story and staggered, one over another, between 300 mm to 1400 mm.
Capital Gate was designed by architectural firm RMJM and was completed in 2011. The tower includes 15,000 square meters of office space and Abu Dhabi's Hyatt hotel.
See also
- List of leaning towers
- List of tallest buildings in Abu Dhabi
- Diagrid
- List of twisted buildings
References
External links
- Capital Gate official website
- Capital Gate Tower at CTBUH website
- The Architects Perspective - The Capital Gate
- the Capital Gate - rmjm
Source of article : Wikipedia
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