Capital Gate Building, Abu Dhabi:
Capital Gate tower in Abu Dhabi is the "World’s furthest leaning man-made tower. At 160 m (520 ft.) and 35 stories, it is one of the tallest buildings in the city. Capital Gate leans 18 degrees to the west, the leaning Tower of Pisa leans only four degrees.
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-centre. Pre-cambering allowed floor plates to be stacked vertically up to the 12th storey, and staggered, one over another between 300 mm to 1400 mm. The Capital Gate was the first building in the world to use a pre-cambered core.
The central core is a vertical structure that provides the central strength, but it also houses what will be the lift and emergency stairwell systems within the building. The core was built at an angle so that as the weight of each concrete slab is added, the centre of gravity of the building pulls the core into its final vertical position. Post-tensioning was used to improve the stiffness of the building.
The building has a diagrid especially designed to absorb and channel the forces created by wind and seismic loading, as well as the inclination of Capital Gate. A diagrid is a framework of diagonally intersecting metal, concrete or wooden beams that is used in the construction of buildings and roofs. It requires less structural steel than a conventional steel frame.
The base of the structure is a concrete raft which is 2m deep solid concrete slab packed with reinforcement to allow it to resist the enormous forces acting on it. It is anchored to the ground by 490 piles which are drilled 20–30 metres underground to accommodate the gravitational, wind and seismic forces caused by the building’s distinctive lean. Conventional piles are compression piles and are designed to resist descending vertical load. Due to the leaning of the building some of the piles are in tension and are designed to resist ascending forces that would otherwise pull the pile from the ground.
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-centre. Pre-cambering allowed floor plates to be stacked vertically up to the 12th storey, and staggered, one over another between 300 mm to 1400 mm. The Capital Gate was the first building in the world to use a pre-cambered core.
The central core is a vertical structure that provides the central strength, but it also houses what will be the lift and emergency stairwell systems within the building. The core was built at an angle so that as the weight of each concrete slab is added, the centre of gravity of the building pulls the core into its final vertical position. Post-tensioning was used to improve the stiffness of the building.
The building has a diagrid especially designed to absorb and channel the forces created by wind and seismic loading, as well as the inclination of Capital Gate. A diagrid is a framework of diagonally intersecting metal, concrete or wooden beams that is used in the construction of buildings and roofs. It requires less structural steel than a conventional steel frame.
The base of the structure is a concrete raft which is 2m deep solid concrete slab packed with reinforcement to allow it to resist the enormous forces acting on it. It is anchored to the ground by 490 piles which are drilled 20–30 metres underground to accommodate the gravitational, wind and seismic forces caused by the building’s distinctive lean. Conventional piles are compression piles and are designed to resist descending vertical load. Due to the leaning of the building some of the piles are in tension and are designed to resist ascending forces that would otherwise pull the pile from the ground.