Site Visit: Regent Emirates Pearl Hotel

The progress made so far on Abu Dhabi's Regent Emirates Pearl Hotel

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
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
ACC anticipates project completion in 2012.
ACC anticipates project completion in 2012.

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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 when needed.”

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 from Germany, 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 “vertical” work.

“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.”

On the ground
Mohsin Khater says the V-shaped columns in the transfer floor will be an interesting architectural highlight on that floor of the building. “We are doing the scaffolding for the transfer slab right now. The V-shaped columns will be an interesting feature. It essentially allows the podium to carry the load. We have some very good designers at ACC to review the design and consult with many people.”

He notes there are five towers next to Regent Emirates Pearl Hotel that share the view of the city and the beach.

“To be honest, we are not having much difficulty with the land,” he says of the small space between developments.

“You try and build the four basement floors as quickly as possible, where you can then store sanitaryware and fire safety equipment.” He compares it to the company’s work on the second phase of the Abu Dhabi Mall, whose construction work on the top was made more complex by the fact that the mall was full of shoppers below.

The company had to get daily permission to allow a trailer to stand outside, he remembers. He said he is constantly impressed by the solutions of companies like Peri, which can provide relatively light, flexible single-sided formwork for the basement, where 20 years ago there was heavier shutterwork carried by cranes.

Project suppliers
Architect: Dennis Lems
Consultant: Arkan Architects Consultants
Main contractor: ACC
MEP: Voltas
Curtain wall: J&H Emirates Company
Plant contractor: ACC’s own supplies
Steel (reinforcement): Cicon Building Materials
Concrete: RMD ReadyMix Beton
Project management: Aconex

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