Monday, 18 April 2016

Design and construction of the world's tallest building:- The Burj Khalifa



The Burj Dubai Tower is the world’s tallest structure, passing all previous height records. Such a project by necessity requires pushing current analysis, material, construction technologies, and building systems to literally new heights. However, as such a building height has never before been attempted, it is also necessary to ensure all technologies and methods used are of sound development and practice. As such, the designers sought to be able to use conventional systems, materials, and construction methods — modified and utilized in new capacities — to achieve such a lofty goal.
The 160-plus-storey Burj Dubai Tower is the centerpiece of a $20 billion multi-tower development located just outside of downtown Dubai. The Burj Dubai project consists of the tower itself, as well as an adjacent podium structure, and separate six-story office annex and two-story pool annex. The 280,000-square-meter (m2) (or 3 million-square-foot, ft2) reinforced concrete multi-use tower is predominantly residential and office space, but it also contains retail space and a Giorgio Armani hotel. The tower and podium structures — combined 465,000 m2 (5 million ft2). It has the space of 35,000 people living under one roof, its like an small city. It completed and inaugurated on 4th January 2010.

Architectural design

The primary design concept of the tower is an organic form with tri-axial geometry and spiraling growth that can be easily seen in the final design. Additionally, traditional Islamic forms were utilized to enrich the tower’s design, and to incorporate visual references to the culture and history of the surrounding region. As such, the floor plan of the tower consists of a tri-axial, “Y” shaped plan, formed by having three separate wings connected to a central core. As the tower rises, one wing at each tier sets back in a spiraling pattern, further emphasizing its height. The Y-shape plan is ideal for residential and hotel use in that it allows the maximum views outward without overlooking a neighboring unit. The wings contain the residential units and hotel guest rooms, with the central core housing all of the elevators and mechanical closets. The tower is serviced by five separate mechanical zones, located approximately 30 floors apart over the height of the building. Located above the occupied reinforced concrete portion of the building is the structural steel spire, housing communication and mechanical floors, and completing the architectural form of the tower. The result is an efficient building in terms of its functionality, structural system, and response to wind, while still maintaining the integrity of the initial design concept.

The tower’s Y-shaped floor plan not only has aesthetic and functional advantages, but is also ideal for providing a high performance, efficient structure.
Foundation 
Pile Foundation of Burj Khalilfa
The tower foundations consist of a solid, 3.7-meter (12.1-foot) thick pile supported raft poured utilizing 12,500 cubic meters (m3) (16,350 cubic yards, yd3) of C50 cube strength (7.25-ksi) self-consolidating concrete (SCC). The raft was constructed in four separate pours (three wings and the center core). Each raft pour occurred during at least a 24-hour period. Reinforcement was typically spaced at 300 mm (12 inches) on center in the raft, and arranged such that every tenth bar in each direction was omitted, resulting in a series of “pour enhancement strips” throughout the raft; the intersections of these strips created 600-mm by 600-mm (24-inch by 24-inch) openings at regular intervals, facilitating access and concrete placement. The tower raft is supported by 194 bored cast-in-place piles. The piles are 1.5 m (5 feet) in diameter and approximately 43 m (141 feet) long, with a capacity of 3,000 metric tonnes (3,300 tons) each. Each was pile load tested to 6,000 metric tonnes (6,600 tons). The diameter and length of the piles represent the largest and longest piles conventionally available in the region. Additionally, the 6,000-metric-tonne pile load test represented the largest magnitude pile load test performed to date within the region. The piles utilized C60 cube strength (8.7-ksi) SCC concrete, placed by the tremie method utilizing polymer slurry. The friction piles are supported in the naturally cemented calcisiltite/conglomeritic calcisiltite formations, developing an ultimate pile skin friction of 250 to 350 kPa (5.2 to 7.3 ksf). A high density, low permeability concrete was used in the foundations, as well as a cathodic protection system under the mat, to minimize any detrimental effects form corrosive chemicals in local ground water.
Pile foundation + Raft Foundation

Wind engineering
For a building of this height and slenderness, wind forces and the resulting motions in the upper levels become dominant factors in the structural design. An extensive program of wind tunnel tests and other studies were undertaken by the wind tunnel consultant, RWDI, in its boundary layer wind tunnels in Guelph, Ontario, to evaluate the effects of wind on building loading, behavior, and occupant comfort. Additionally, the wind tunnel testing program was utilized as part of a process to shape the building to minimize wind effects. As mentioned above, this process resulted in a substantial reduction in wind forces on the tower by confusing the wind — by encouraging disorganized vortex shedding over the height of the tower. The wind tunnel testing program included rigid-model force balance tests, a full aeroelastic model study, measurements of localized pressures, and pedestrian wind environment studies. Wind statistics played an important role in relating the predicted levels of response to return period. Extensive use was made of ground-based wind data, balloon data, and computer simulations employing Regional Atmospheric Modeling techniques to establish the wind regime at the upper levels. Based on the results of the wind tunnel testing program, the predicted building motions are within the ISO standard recommended values without the need for auxiliary damping. 
An extensive program of wind tunnel tests and other studies resulted in a substantial reduction in wind forces on the tower by confusing the wind.  
Construction methods and technology
The Burj Dubai Tower utilizes the latest advancements in construction techniques and material technology. The walls are formed using Doka’s SKE 100 automatic self-climbing formwork system. The circular nose columns are formed with circular steel forms, and the floor slabs are poured on MevaDec panel formwork. Wall reinforcement is prefabricated on the ground to allow for fast placement. Three primary self-climbing Favco tower cranes are located adjacent to the central core, with each continuing to various heights as required. The cranes have been specially modified to be able to lift the extreme lengths of cable required, as well as 25-metric-tonne (27.5-ton) payloads, at high speeds. High-speed (120-m/minute, 393-foot/minute), high-capacity (3,200-kg, 7,050-pound) construction hoists were used to transport workers and materials to the required heights. Because of limitations of conventional surveying techniques, a specialized GPS monitoring system has been developed to monitor the verticality of the structure.
The construction sequence for the structure has the central core and slabs being cast first, in three sections; the wing walls and slabs follow behind; and the wing nose columns and slabs follow behind these. Concrete is distributed to each wing utilizing concrete booms that are attached to the jump form system. Two of the largest concrete pumps in the world were used to deliver concrete to heights over 600 m (1,968 feet) in a single stage. A horizontal pumping trial was conducted prior to the start of the superstructure construction to ensure pumpability of the concrete mixes.
 

Podium
The podium provides a base anchoring the tower to the ground, allowing on grade access from three different sides to three different levels of the building. Fully glazed entry pavilions constructed with a suspended cable-net structure provide separate entries for the Corporate Suites at B1 and Concourse Levels, the Burj Khalifa residences at Ground Level and the Armani Hotel at Level 1.  

Exterior Cladding
The exterior cladding is comprised of reflective glazing with aluminum and textured stainless steel spandrel panels and stainless steel vertical tubular fins. Close to 26,000 glass panels, each individually hand-cut, were used in the exterior cladding of Burj Khalifa. Over 300 cladding specialists from China were brought in for the cladding work on the tower. The cladding system is designed to withstand Dubai's extreme summer heat, and to further ensure its integrity, a World War II airplane engine was used for dynamic wind and water testing. The curtain wall of Burj Khalifa is equivalent to 17 football (soccer) fields or 25 American football fields.

Spire
The crowning touch of Burj Khalifa is its telescopic spire comprised of more than 4,000 tons of structural steel. The spire was constructed from inside the building and jacked to its full height of over 200 metres (700 feet) using a hydraulic pump. In addition to securing Burj Khalifa's place as the world's tallest structure, the spire is integral to the overall design, creating a sense of completion for the landmark. The spire also houses communications equipment.

Mechanical Floors
Seven double-storey height mechanical floors house the equipment that bring Burj Khalifa to life. Distributed around every 30 storeys, the mechanical floors house the electrical sub-stations, water tanks and pumps, air-handling units etc, that are essential for the operation of the tower and the comfort of its occupants.

Window Washing Bays
Access for the tower's exterior for both window washing and façade maintenance is provided by 18 permanently installed track and fixed telescopic, cradle equipped, building maintenance units. The track mounted units are stored in garages, within the structure, and are not visible when not in use. The manned cradles are capable of accessing the entire facade from tower top down to level seven. The building maintenance units jib arms, when fully extended will have a maximum reach of 36 meters with an overall length of approximately 45 meters. When fully retracted, to parked position, the jib arm length will measure approximately 15 meters. Under normal conditions, with all building maintenance units in operation, it will take three to four months to clean the entire exterior facade. 

Broadcast and Communication Floor
The top four floors have been reserved for communications and broadcasting. These floors occupy the levels just below the spire.

Fire Saftey
Fire safety and speed of evacuation were prime factors in the design of Burj Khalifa. Concrete surrounds all stairwells and the building service and fireman's elevator will have a capacity of 5,500 kg and will be the world's tallest service elevator. Since people can't reasonably be expected to walk down 160 floors, there are pressurized, air-conditioned refuge areas located approximately every 25 floors.

Mechanical, Electrical & Plumbing
To achieve the greatest efficiencies, the mechanical, electrical and plumbing services for Burj Khalifa were developed in coordination during the design phase with cooperation of the architect, structural engineer and other consultant.
The tower's water system supplies an average of 946,000 litres (250,000 gallons) of water daily
At peak cooling, Burj Khalifa will require about 10,000 tons of cooling, equal to the cooling capacity provided by about 10,000 tons of melting ice
Dubai's hot, humid climate combined with the building's cooling requirements creates a significant amount of condensation. This water is collected and drained in a separate piping system to a holding tank in the basement car park
The condensate collection system provides about 15 million gallons of supplement water per year, equal to about 20 Olympic-sized swimming pools
The tower's peak electrical demand is 36mW, equal to about 360,000 100 Watt bulbs operating simultaneously.


Elevators and lifts
Burj Khalifa will be home to 57 elevators and 8 escalators The building service/fireman's elevator will have a capacity of 5,500 kg and will be the world's tallest service elevator.
Burj Khalifa will be the first mega-high rise in which certain elevators will be programmed to permit controlled evacuation for certain fire or security events. Burj Khalifa's Observatory elevators are double deck cabs with a capacity for 12-14 people per cab. Traveling at 10 meters per second, they will have the world's longest travel distance from lowest to highest stop.


The Burj Dubai

Owner
Emaar Properties PJSC, Dubai


Project manager
Turner Construction International


Architect/Structural engineers/ MEP engineers
Skidmore, Owings & Merrill LLP


Adopting architect and engineer/Field supervision
Hyder Consulting Ltd.


General contractor
Samsung/BeSix/Arabtec


Foundation contractor
NASA Multiplex



By the Numbers: Burj Dubai
Size, shape, and type
Number of square feet: 3 million ft2 (280,000 m2)
Number of stories: 160+
Structural system types: concrete with structural steel spire
Foundation type: concrete raft on piles
Construction quantities  
Concrete: 327,000 yds3 (250,000 m3)
This is equivalent to:  
  A solid cube of concrete 63 meters (207 feet) on a side,
A sidewalk 2,065 kilometers long (1,283 miles),
More than five times the volume of concrete used for the CN Tower in Canada, or
The weight of 110,000 elephants
Rebar: 35,700 metric tonnes
  Laid end to end this would extend over a quarter of the way around the world
Curtain wall: 83,600 m2 (20.7 acres) of glass and
27,900 m2 (6.8 acres) of metal; 111,500 m2 (27.5 acres) total
  Equivalent to 17 soccer fields or 25 American football fields


Hope I'm able to give enough Information, Any query, suggestion, request please comment below...
Thanks,

2 comments:

  1. I think the picture of "pile foundation of Burj khalifa" is not burj khalifa. It is Kingdom Tower at Jeddah. The piles of Burj khalifa is not that deep.

    ReplyDelete
    Replies
    1. Yes I agree with abc thats the pile raft foundation for Jeddah Tower

      Delete