Gulf Construction Online - Doka in prime role on Prime Tower

Dubai Review

Doka formwork at Prime Tower ... helping speedy construction.

Doka in prime role on Prime Tower

01 April 2009

DESPITE the fast-track construction requirement and complex architectural features of the 60-storey Prime Tower, formwork systems from Doka are proving what can be achieved with efficient planning and sophisticated systems on the residential project in Dubai.

The tower, situated just around the corner from the luxury hotel Shangri La, offers nearly 50,000 sq m of exclusive apartment space that enjoys panoramic views out across the sandy beaches of Dubai.
The 227-m-tall in-situ concrete core and the punctuated facade are both being built at record speed using SKE 50 formwork. Doka equipment is also in service for the cast-in-place concrete floor slabs.
“Execution time is a critical factor in this project,” says Youssef El Badawi, general manager of Al Ashram Contracting and Doka’s partner for the design of the formwork solution. “What is more, the architect’s choice of a punctuated facade constructed in cast-in-place concrete involves much more work and expense in the shell construction phase than would column-supported flat-slab floors with a curtain-wall-type punctuated facade.”
The punctuated facade comprises 1.2-m-high in-situ concrete downstand beams and 28 columns on each storey. In order to meet the timetable of a weekly cycle for each storey, Doka’s branch in Dubai and Al Ashram designed a forming workflow, allowing the core and punctuated facade to be climbed separately.
In this sequence, the automatic climbing brackets for the punctuated facade, complete with the fitted Doka large-area formwork Top50, are all “jumped” from one casting section to the next as a single unit. To take on this challenge, Doka planned a flexible formwork solution that allowed the columns and downstand beams to be poured using one and the same formwork element.
“The formwork for the outside of the downstand beam and the outside of the column consists of a single element. Also, the side-formworks for the columns are integrated in this element, and can be hinged back to facilitate setting up and striking the formwork,” explains El Badawi.
A further challenge here was that the quadratic layout of the columns is reduced by 100 mm after every 15th storey. With the versatile Top50 large-area formwork, these recurring setbacks are incorporated in the design of the formwork and, therefore, accomplished without difficulty and quickly, he explains.
The concrete core also has a quadratic layout and is being constructed using 49 SKE 50 automatic climbers. The core comprises nine shafts that are independent of one another, which are also being “climbed” with SKE 50 automatic climbers.
“This allows much easier access for cleaning the formwork and for placing the reinforcements and the box-outs,” says Martin Hörlesberger, Doka’s project manager for self climbing systems.
To speed up the climbing operation, gangs of up to three shaft formworks are raised together in some cases. Turning to the punctuated façade, Hörlesberger elaborates that the forming sequence was divided into three steps. “First, the in-situ concrete slab, including the downstand beams, is cast. This is done using the hand-set system Dokaflex 1-2-4, which is easy to set up.
“Then the two side elements of the column formwork are folded inwards and the remaining formwork for the inside of the column set down on the floor slab, completing and closing the column formwork. The columns are then poured up to the bottom edge of the downstand beam above them.
“After the formwork has been struck, it is ‘jumped’ to the next casting section on the SKE 50 automatic climbers, at the push of a button. In total, 7,000 m of in-situ concrete downstand beams and 1,680 columns are being constructed in this way. For this, 32 units of SKE 50 are in service, all of which are controlled from a single hydraulic unit.
“As with the automatic climbing formwork for the concrete core, the generously-sized main working platforms and the two follow-up platforms are enclosed with solid trapezoidal sheeting to ensure maximum workplace safety,” he explains.
With this comprehensive formwork solution and the meticulously-planned forming workflow, the Al Ashram site crew is able to reinforce, form and cast one storey, including the punctuated facade and in-situ concrete core, in only five days.
Owing to the residential buildings adjoining the site, night-time construction operations are limited to concrete placement only. Without this restriction, a four-day cycle could easily have been achieved, says El Badawi.