Burj Khalifa

The Burj Khalifa tower is the world’s tallest structure. The 280,000 m2 reinforced concrete multi-use tower is utilized for Retail, a Giorgio Armani Hotel, Residential, and Office. The goal of the Burj Khalifa is not simply to be the world’s highest building; it’s to embody the world’s highest aspirations. Designers purposely shaped the structural concrete Burj Khalifa—“Y” shape in plan—to reduce the wind forces on the tower, as well as to keep the structure simple and foster constructability. The structural system can be described a “buttressed” core. Each wing, with its own high performance concrete core and perimeter columns, buttresses the others via a six-sided central core, or hexagonal hub. The result is a tower that is extremely stiff torsionally. SOM applied a rigorous geometry to the tower that aligned all the common central core and column elements to form a building. Each tier of the building steps back in a spiral stepping pattern up the building. The setbacks are organized with the tower’s grid, such that the building stepping is accomplished by aligning columns above with walls below to provide a smooth load path. This allows the construction to proceed without the normal delays associated with column transfers. The setbacks are organized such that the tower’s width to change at each setback. The advantage of the stepping and shaping is to “confuse the wind.” The wind vortexes never get organized because at each new tier the wind encounters a different building shape. Designers purposely shaped the structural concrete Burj Dubai—“Y” shape in plan—to reduce the wind forces on the tower, as well as to keep the structure simple and foster constructability. The structural system can be described a “buttressed” core. Each wing, with its own high performance concrete core and perimeter columns, buttresses the others via a six-sided central core, or hexagonal hub. The result is a tower that is extremely stiff torsionally. SOM applied a rigorous geometry to the tower that aligned all the common central core and column elements to form a building. Each tier of the building steps back in a spiral stepping pattern up the building. The setbacks are organized with the Tower’s grid, such that the building stepping is accomplished by aligning columns above with walls below to provide a smooth load path. This allows the construction to proceed without the normal delays associated with column transfers. The setbacks are organized such that the Tower’s width to change at each setback. The advantage of the stepping and shaping is to “confuse the wind.” The wind vortexes never get organized because at each new tier the wind encounters a different building shape. Sustainable Design The Burj Dubai, currently the world’s tallest building, is the centerpiece of a large scale mixed use development comprised of residential, commercial, hotel, entertainment, shopping and leisure outlets with open green spaces, water features, pedestrian boulevards, a shopping mall and a tourist-oriented old town. The design for the 270,000 sm tower combines historical and cultural influences with cutting edge technology to achieve a high-performance building that will set the new standard for development in the Middle East and become the model for the future of Dubai. When designing the Burj Dubai, the design team looked to the sky for sustainable elements. In the extreme hot and humid climate of Dubai, the temperature between the ground (46.1ºC or 115 ºF) and the top of the building (38ºC or 100ºF) can vary up to 8 ºC (or 15º F). Satellite data was used to predict the humidity drop with altitude (up to 30% reduction in humidity between the top and bottom of the building), and analysis was performed to study the air density drop up the building (up to 10%). SOM’s “sky sourced” sustainability innovations will result in substantial energy savings. The Burj Dubai also has one of the largest condensate recovery systems in the world, capturing up to fourteen Olympic size swimming pools of water per year, and one of the highest chilled water pressures ever used in a building to maximize efficiency. The tower is one of the first to utilize an active stack effect control in a super tall building to minimize energy loss.

[IT]

La “torre del deserto” vanta misure sconcertanti: 162 piani per 828 metri di altezza (se si include la guglia), con una superficie di 334mila metri quadrati e 58 ascensori che viaggiano ad una velocità di 10 metri al secondo. All’interno trovano spazio uffici, centri commerciali ed appartamenti di lusso, nonché il primo Armani Hotel al mondo (dal 37° al 45° piano) con 160 stanze e 3mila mq di sale conferenze e spazi per eventi. L’Hotel Armani aprirà ufficialmente il 18 marzo prossimo. Un belvedere al 124° piano, la piattaforma di osservazione più elevata sino ad ora realizzata, offre una spettacolare vista di Dubai a 360 gradi. L’ambizioso progetto – al quale hanno lavorato oltre 380 ingegneri – è stato costruito in cinque anni ed ha comportato una spesa di oltre 4 miliardi di dollari. Sono stati impiegati circa 45mila metri cubi di calcestruzzo, 330mila tonnellate di cemento e 31400mila tonnellate di acciaio. Il design strutturale a nido d’ape, con molti elementi di rinforzo simili a quelli della struttura dei velivoli, è stato realizzato con ben 430mila mq di pareti, pari ad una superficie doppia rispetto a quella dei solai. Di chiara ispirazione islamica, la geometria del Burj Dubai ricorda il fiore del deserto, tipico della regione. La torre si compone di tre elementi in vetro e calcestruzzo che si sviluppano attorno ad un nucleo centrale salendo verso il cielo come scalini. Un arretramento su ciascun elemento snellisce il corpo dell’edificio man mano che questo continua la sua ascesa nello skyline. Giunto all’estremità, il cuore della torre emerge come uno stelo d’erba. La base particolarmente larga della torre – a forma di Y – consente di ridurre l’impatto delle correnti d’aria dovute ai vortici che spesso nascono nelle zone più alte dei grattacieli. “Il sistema strutturale – spiega Bill Baker dello studio SOM – può essere definito un nucleo di sostegno a sei lati in cui ciascuna ala, con il suo nucleo in cemento altamente performante e le colonne perimetrali, sostiene le altre”.