By Benjamin Roberts
The Regent Emirates Pearl Hotel being buit by ACC is part of a cluster of hotel developments on Abu Dhabi’s Corniche
The public and private investment in Abu Dhabi has transformed
its city centre in the last two years, with hotel building plentiful to accommodate
rising numbers of visitors in addition to schools, roads, bridges and hospitals
springing up for residents.
The Regent Emirates Pearl Hotel is one such swift-moving development
to the west of the city. It is, in fact, surrounded by other hotel developments
in a dense, fenced-off hub of construction activity, off the roundabout at the end
of Corniche Road.
Main contractor ACC has been coordinating construction of the 47-storey hotel tower
since last March, whose site office backs onto the water that separates the mainland
from Coconut Island.
The client is Emirates Pearl for Development and Investment,
a joint venture between Altas Telecom and the Tourism Development & Investment
Company. Designed by Dennis Lems Architects Associates, with consultancy services
provided by Arkan Architects Consultants, the hotel will offer sea views front and
back for those high enough in the palatial apartments.
At this stage of construction, the project can be divided into
two parts. The first is the area in which the circular podium for the main tower
stands that sits on four basement levels. The structure so far, which includes a
platform level that will be sandwiched between the podium and the tower, is still
clamped in heavy-duty scaffolding. The second part is the rest of the basement area
that juts far out in front of the podium in the direction of the Corniche. This
area is still a vast, open area filling up with concrete and steel that shows the
depth of the four basements underneath that will house hundreds of cars and will
feature a roundabout on the ground level.
Beyond the small amount of space inbetween the different tower
projects, the area is further challenged by a single entrance from the road that
winds around some of the other structures. ACC has had to coordinate closely with
its neighbouring contractors when materials and vehicles are needed to arrive at
a certain time so as to minimise disruption.
“At the beginning it took a lot of planning to decide where to
put the temporary buildings and labour facility, particularly when constructing
the raft,” said Maged Rofail, project manager at ACC. “There is no space for every
material, so you have to coordinate with the supplier so that everything arrives
ACC came to the project with the piling completed, though had
to work hard to find a solution for excavating the whole area. With little room
to create a ramp, the company opted to use three excavators working at different
levels of the digging work – the bottom, middle and the top – with the earth passed
up in a chain. “The bottom excavator passes the earth up to the middle, and the
middle onto a six-wheeled truck,” says Mohamed Hasson, construction manager. “In
a confined space, this made it much easier. We faced a problem when finishing the
last part, as it was in a corner where you could only get one excavator, and we
were only digging up perhaps 800m3. So we had only space for one excavator down
there, and needed a sand bucket to lift the earth out. That took more time, but
it was a success.
“This is an unusual system: if there is an open excavation, such
as the Sky Towers projects, then you can do so around
building and so have space to make a ramp. In our case, we had to build the inner
wall and so had no space for open excavation.”
Today, the basement underneath the podium is complete, as are
the slabs for levels two and three in the vast part of the basement that is in front
of the podium. Hasson says laying the slab for basements takes a lot longer than
those for a tower as it is not ‘typical’ work: each area of the basement is different
in terms of dimensions, and is surrounded by a concrete retaining wall. These slabs
take about 10 days to finish; roughly twice the time estimated for the slabs of
the tower when the floor-building cycle is in full swing.
At present, the company has almost finished the tricky platform
level, which is the floor between the podium and what will be the hotel tower. The
platform level essentially normalises the weight distribution between the specific
structure of the tower and that of the podium. On top of the podium below level
one are V-shaped supporting columns that will reinforce support for the tower.
“Normally, the columns of the tower are not suitable for this
podium. That is why we have the transfer level,” explains Hasson. Today these V-columns,
which are partly up the podium, are reinforced steel skeletons waiting for the concrete
pour. Rofail points out that they will make for an interesting architectural feature
around the edge of the podium’s interior, particularly for the restaurant that will
be fitted-out on the second floor of the podium.
The podium floors are 6m apart, except for the roof floor, which
is 7.9m, with a slab height of 60cm. The core wall of the podium, which is elliptical,
will be taking two-thirds of the weight of the tower. The unusual shape of the core
wall needed to be supported in construction by Peri’s Vario system, which had to
be fabricated specially for the project to mirror that of the core wall.
“Due to the curvature, we had steel walers, which act as the
backbone for the Peri structure, made in that specific shape,” explains Amjad Khan,
area sales manager at Peri. “For this we needed to procure some special materials
as well as the specific calculations for the placing boom, which fixes the hoses
in place that will pump the ready-mix concrete to create the core wall.”
Climbing up the podium through the winding stair case around
the elliptical core, Hasson explains how the company has used Peri’s Automatic Climbing
System (ACS) for the core wall and its Tableform system for slabs. The ACS system,
a structure that clings to the core wall over a few floors, takes a little bit of
time to assemble, he says. “While making the raft, we will start making the ACS
system so that we can start immediately making the core wall when we are ready.”
The ACS system sits on a rail that slides the structure up against
the wall at the time of pouring and can then be unlocked, lifted by hydraulics and
re-clamped to the wall on the next level up for the next round of pouring. Khan
explains that, on the first floor, the system needs to be aided by a crane until
the system is up and running on the rail.
The V-shaped columns are not the only vertical innovation in
this area, Hasson explains: the columns of the tower will tilt 45° and appear to
gradually snake round the building one floor at a time.
“The columns are placed at a position that is 44cm different
from the columns on the previous floor. There are four dots on the floor in a square
which show where the column on the floor below is positioned. Essentially we just
place the bottom left corner of the next column on the top right dot, so that the
columns gradually make their way around the whole building.”
ACC is scheduled to complete the entire project by the second
half of 2012. Hasson says there have only been minor design changes since the project’s
conception, which is to be expected.
As the basement slab for the first floor nears completion, the
company can start erecting the hotel’s core wall and, close behind, the regular
cycle of laying slabs. The latter process will take four to five days, with half
of one slab cast while the other half of the team gets on with what Hasson calls
“Usually we are casting overnight. If we did the whole slab at
once, then you would not have access to the slab the following day, and so would
lose a day’s work,” he says.
“The intelligent way is to make the slab in two parts: one half,
you are casting the concrete; the other half, you are doing the vertical works –
the decking for the slab, the steel reinforcement – and then these two activities
can be swapped.”