WITH the spectacularly-inclined Capital Gate currently under construction in Abu Dhabi, the emirate is putting up some serious competition to neighbouring Dubai in terms of record-breaking construction projects.

Whereas the Leaning Tower of Pisa is four degrees out of the vertical, Capital Gate is inclined by a massive 18 degrees, making it more than four times as crooked as the famed Italian campanile.
With its extreme inclination, this tower 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 contractor Al Habtoor Engineering Enterprises 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, according to a spokesman for Doka, the Austria-headquartered formwork manufacturer.
“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,” he says.
The central in-situ concrete core of Capital Gate 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, he says.
A total of 78 units of the powerful Doka automatic climbing formwork SKE 50, and more than 1,300 sq m of large-area formwork Top 50, are 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 Top 50 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 steel form-facing. This enhancement has been implemented based on the insights gained by Doka during the two-and-a-half-year climbing assignment on the Burj Dubai, according to the spokesman.
He continues: “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.
“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.”
With the use of a powerful hydraulic unit, up to 30 climbing brackets can be raised at a time. The platforms of the automatic climbing formwork were supplied to the site completely pre-assembled by Doka, 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 Zakaria, acting project director of Adnec, developer of Capital Gate.