Gulf Construction Online - Pinnacle of glory!

Dubai Review

The rise of Burj Dubai ... from its foundations in 2004.

Pinnacle of glory!

01 April 2009

MORE than 8,500 professionals and skilled workers are currently on site putting the final elements of the cladding works and interiors in place for what is now the world’s tallest building.

The Burj Dubai, which makes a dramatic statement of engineering excellence as well of Dubai ambitions on the horizon, is on course to open in the last quarter of this year, according to its developer Emaar Properties.
Cladding work is nearing completion and work on interiors, the spire and other support systems is progressing.
“Cladding work on the pinnacle is ongoing, and the pinnacle is now lifted at a great height while awaiting the client’s decision on where to set the final height,” Ahmad Abdelrazaq, executive vice-president, Highrise & Structural Engineering Division of Samsung Corporation, tells Gulf Construction in an exclusive interview.
“The building is expected to have a soft opening sometime this year, the date of which will be announced soon,” he adds.
Elaborating on the technique being used to install the pinnacle on top of Burj Dubai, he says: “The pinnacle was assembled from within the building. The base of the pinnacle and transfer system was installed at Level 156 and was lifted after the entire pinnacle was assembled. The 25 structural steel pipe pieces of the pinnacle were assembled as the structural steel of the spire was being erected. The pinnacle pipe sizes vary from 2.1 m diameter at the base with thicknesses varying from 60 to 50 mm to 1.2 m diameter and 3-mm thick at the top. The pinnacle will be lifted from Tier 21B with three heavy-duty 300-tonne-capacity hydraulic jacks. The entire assembly of the jacking system was supplied and operated by VSL. Six heavy-duty guide rollers are provided simultaneously at three levels to provide lateral support for the pinnacle and to control its verticality during lifting. The cladding was installed during the lifting operation.
“The entire operation went very smoothly, and the installation of the pinnacle was done to within H/4000 tolerance of its final lateral position, which demonstrates the efficiency of the lifting techniques that was engineered and managed by Samsung.”
Another crucial consideration was the wind engineering management technique to control the behaviour of the pinnacle under wind, he points out.
“Initially, chain dampers were to be deployed to control the motion of the pinnacle. However, during a workshop in 2005, Samsung suggested the removal of the pinnacle cladding and replacing it with cladding fins in helical form to reduce the effect of vortex shedding on the pinnacle. Wind tunnel testing indicated that the forces on the pinnacle were significantly reduced, and the pinnacle vibration due to vortex shedding was also reduced, thus resulting in a reduction in the pinnacle pipe thickness and the elimination of the chain dampers.”
It has taken close to 2,002 Arabian nights to create this iconic structure since excavation began on site in January 2004. Over this time, the project has set several global milestones in high-rise construction. At a current height of over 780 m (2,559 ft), Burj Dubai has now also scaled over 160 levels, the most number of storeys in any building in the world. It has surpassed the height KVLY-TV mast (628.8 m) in North Dakota, US. The tower is also taller than Taipei 101 in Taiwan, which at 508 m has held the tallest-building-in-the-world title since it opened in 2004. Burj Dubai also surpassed the 31-year-old record of CN Tower, which at 553.33 m has been the world’s tallest free-standing structure on land since 1976.
When completed, Burj Dubai will meet all four criteria listed by the Council on Tall Buildings and Urban Habitat (CTBUH), which classifies the world’s tallest structures. CTBUH measures the height of buildings to the structural top, the highest occupied floor, the top of the roof and the tip of the spire, pinnacle, antenna, mast or flag pole.
The world’s fastest high-capacity construction hoists, with a speed of up to 2 m/sec (120 m/min) have helped move men and materials. When completed, the tower will have used 330,000 cu m of concrete, 39,000 tonnes of steel rebar and 142,000 sq m of glass – and 22 million man-hours.
Leveraging on the advancements in construction engineering, Burj Dubai undertook height enhancement last year and is also upgrading its interior finishes. International designers from California have revised the designs to make the residences more attractive and functionally superior.
'Last year was a landmark year for Burj Dubai, as it consolidated its global leading position in the construction of high-rises. Every aspect of Burj Dubai, now, is a world-first, and highlights the new aspects of construction technology employed for the tower,' says Ahmad Al Matrooshi, managing director – UAE, Emaar Properties.
A mixed-use tower, Burj Dubai will have 2 million sq ft of residential and over 220,000 sq ft of prime business space. It will be home to The Armani Hotel Dubai, and Armani Residences, the luxury hospitality ventures by Emaar in association with haute couture major Giorgio Armani. The skyscraper will also have recreational facilities and entertainment venues including four luxurious pools and a cigar club, a library, exclusive residents’ lounge, serviced residences, 15,000 sq ft of fitness facilities and a public observatory on Level 124.
Designed by Chicago-based Skidmore, Owings & Merrill (SOM), Burj Dubai is constructed by high-rise experts South Korea’s Samsung Corporation. Turner Construction International is the project and construction manager.
Burj Dubai, which has a development value of over $1 billion, anchors Emaar’s flagship mega-project, the Dh73 billion ($20 billion) Downtown Burj Dubai. Described as the new heart of the city, Downtown Burj Dubai is a mixed-use neighbourhood with premium hotels, exclusive business facilities, modern residences, shopping malls and leisure facilities.
The design inspiration for Burj Dubai is drawn from the desert flower, Hymenocalis, and incorporates patterning systems that are embodied in Islamic architecture. The tower is designed as three petals arranged around a central core. As the tower rises from the flat base, the petals setback in an upward-spiralling pattern.
Burj Dubai’s structure has employed the latest advances in wind engineering, structural engineering, structural systems, construction materials and construction methods. It has a high-performance exterior cladding system to withstand the harsh summer temperatures.
Commenting on the challenges in constructing the world’s tallest tower, Abdelrazaq says: “The project is more than 160 floors with a height exceeding 800 m, and with very limited time to finish. To undertake the structural works in a three-day cycle to enable its completion within the allocated time, Samsung JV utilised the latest construction technologies available today. This included the optimisation of equipment, the process of managing people up/down the tower, excellent construction planning and logistics, pumping high-strength, high-durability concrete to a new record of 600 m without any difficulty, achieving concrete with high modulus of elasticity, which contributes to stiffness without the added mass, and most importantly keeping the site safe and clean.
“Burj Dubai is very tall and slender and it was built to a very tight construction – 25 mm of tolerance – in a concrete building, which is difficult to achieve in steel buildings with a similar height. Samsung had also provided an extensive structural health monitoring programme for the tower that was never done before.”
At the turn of the century, people never thought these heights could be reached with concrete, but Burj Dubai is a testament to the efficacy of the high-strength system for super-tall towers, Abdelrazaq points out.
“With the Burj Dubai project, we have achieved Emaar’s vision of establishing a new milestone in tall buildings in every aspect and it is a great accomplishment in the history of engineering,” he concludes.

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