World record for “Leaning Tower of Abu Dhabi”
The United Arab Emirates are constantly outdoing one another with record-breaking construction projects.Be it the tallest building in the world, its largest artificial island landscape or its most luxurious hotel, all of these spectacular structures are massed here around the entrance to the Arabian Gulf. With the spectacularly inclined Capital Gate Tower, currently under construction in Abu Dhabi, the Emirate is putting up some serious competition.
Slanted 18 degrees from the vertical, the Capital Gate Tower is the most steeply inclined building in the world. Main contractors Al Habtoor are raising the 160 m high in-situ concrete core using 78 Doka SKE 50 automatic climbers.
Capital Gate is inclined by a massive 18 degrees, making it more than four times as crooked as the famed Pisa tower. With its extreme inclination, this tower – designed by the prestigious global architectural practice of RMJM Architects – is testing the limits of what is technically feasible, calling for outstanding performance from everyone involved in the project.
For constructing the central in-situ concrete core, main contractors Al Habtoor Engineering Enterprises Co. LLC.opted for an automatic climbing formwork from Doka.
As well as Al Habtoor’s very satisfactory experience on past projects, the main deciding factors here were the technically convincing formwork solution and the comprehensive package of services designed to optimise all phases of the forming operations.
This means that Doka now holds the automatic climbing record not only for the world’s tallest building (Burj Dubai), but also for its most inclined high-rise tower. After its scheduled completion at the end of 2009, this extraordinary tower will merit an entry in the “Guinness Book of Records”, a distinction that it is likely to retain for years to come.
The 160 m high tower is being constructed on an extremely densely reinforced concrete foundation poured from more than 6000 m³ of high-performance concrete, which in turn rests on 490 bored piles sunk 30 m into the ground.
This colossal volume of concrete was hauled to the site in 850 truckloads in the space of only 30 hours, and placed with the aid of 5 high-performance concrete pumps.
The central in-situ concrete core of the Capital Gate Tower is characterised by an elliptical layout and a large number of shafts, and is back-stayed into this massive reinforced concrete foundation. This transfers the horizontal loads resulting from the extreme inclination, and secures the tower against both wind loads and earthquakes.
There are 78 units of Doka automatic climbing formwork SKE 50 and more than 1300 m² of large-area formwork Top 50 in service for forming the in-situ concrete core. Due to the increased concrete pressure resulting from the inclination of the shaft-walls, the large-area formwork is reinforced with extra steel walings.
In addition to this, the corner zones of the Top 50 elements are fitted with specially made steel walings and reinforced with a steel form-facing. This improvement results from the insights gained by Doka during the 2½-year climbing assignment on the Burj Dubai.
Owing to the extreme slant of the structure, the SKE 50 automatic climbers are safely guided up the structure core with the aid of suspension shoes specially developed for this task. In order to increase the load-bearing capacity of the climbing brackets and working platforms while ensuring equally safe anchoring in the structure, thicker tie-rods are used than would otherwise be the norm.
With the climbing scaffolds firmly anchored in the concrete at all times, and the work-platforms railed-in on all sides, maximum workplace safety is ensured during all phases of the forming operations. The formwork for the inside walls of the shafts is hung from a massive gallows construction which is mounted on the climbing brackets so that it can simply be raised along with the entire climbing scaffold.
Final height of 160 m
Using this high-performing automatic climbing formwork system, the Al Habtoor site crew is able to form, reinforce and pour one casting section every week. A total of 42 casting sections are being carried out here with no change of form-facing.
The use of a powerful hydraulic unit enables up to 30 climbing brackets to be raised at a time. The platforms of the automatic climbing formwork were supplied to the site by Doka completely pre-assembled, and were then set up under the supervision of an experienced field service technician.
“Doka has fulfilled the tough requirements for this formwork assignment to our complete satisfaction. In particular, it was the detailed planning of the forming operations, the comprehensive oversight provided during the shell construction phase and the high safety standard of the automatic climbing formwork that convinced us”, emphasises Mohammad F. Zakaria, Acting Project Director, ADNEC Phase 3 Capital Gate.