Font Size

- Aa +

Sat 13 Mar 2010 04:00 AM

Font Size

- Aa +

Sitting on top of the Bay

One of Business Bay's most ambitious projects, the complex U-Bora towers continue to rise from the ground. We drop in to see an enormous steel section being hoisted into place.

One of Business Bay's most ambitious projects, the complex U-Bora towers continue to rise from the ground. We drop in to see an enormous steel section being hoisted into place.There was talk a couple of months ago about the UN moving its headquarters from New York to Dubai. If you read the story, then you might remember that this was fuelled by a US academic who suggested that the building that houses the talking shop was too far away from the world's population centres, was falling down through years of over use and neglect, and anyway was resented by the majority of the Big Apple's residents for being an expensive way to snarl up traffic on a regular basis.

The professor argued that Dubai on the other hand, was perfect for the task - and the place he suggested was most perfect, was Downtown Burj Khalifa's Business Bay.

Now, there is absolutely no suggestion that the UN would or has ever considered relocating to the Middle East, though the government did issue a statement saying that the body would be most welcome if it chose to come, but if it did, then we can see why the leather-patched lecturer specifically mentioned Business Bay.

Put simply, it is where most of us would aspire to work, and the sweeping, mixed-use towers are ideally suited for large organizations who want their white-collar staff to work and live in the same place. Apart from the practical benefits, such a development is also very secure, but being a stone's throw from the Dubai Mall and the rest of the city it will hardly feel like being confined to barracks.

Self Development

There are lots of these mixed-use projects in Business Bay, but one of the most noteworthy is the U-Bora towers. Being built by Korean firm Bando, the project consists of a large five-storey podium onto which a curved residence building, with a roofline that sweeps from 12 levels at one end, up to 16 at the other, as well as a magnificent 56-storey office tower, with a sail-like curved side.

Every single floor of this business tower was snapped up by a foreign hedge fund firm, off-plan, back in 2006, before a single bore was cast. Meanwhile, the residence was sold in two phases to private investors.  As an aside, the term ‘Bando' has a double meaning, as literally translated it means ‘self development'.

The build was started back in 2007, initially with Simplex acting as subcontractor. The subcontractor left site in September 2008, leaving Bando both as developer and lead contractor. Like most of Dubai, the project was launched with massive optimism, and the residences sold out fast thanks to a payment scheme where investors could put 20% down and pay the remainder on handover. This lead the off-plan apartments to change hands at one stage for a reported AED3000 per square foot.

The market has changed considerably now of course, but Bando are still confident that the market wants a building constructed to the highest standards of design and finish. However, due in part to the market and also because of the challenging design, the build is running behind the originally projected completion date of September 2009. That said, the project is progressing at a steady rate again and project director Jae Myung Park told us that the building would still be ready at the end of the year. Steel moving

CW visited on a special day in the project, as a huge pre-fabricated steel extrusion said to weigh as much as 270 tonnes is being fitted to the top of a cut-out in the residence block. This huge piece of metalwork spans 35 meters and consists of heavy trusses, beams and pipe bracings. Each truss has top chord, bottom chord, diagonal members and connection plates.

There are always a great number of workers scurrying around the site, but now there is a number more, as specialists from metal maker Techno Steel, as well as the firms that provide the gear to climb it up the building. "I've checked the records and today we have more than 1,500 people on site," says the project coordinator Kim Myung Jin.

It would have just about been possible to build a scaffold and assemble the steel structure in situ, but the amount of delay and costs to the project meant that alternatives needed to be looked at. Fortunately, moving extremely heavy metal is one thing specialists in Dubai are skilled at doing, so two teams of specialists were brought in to move the section in two phases.

Strongest

After the prefab section arrived on a low loader from the steelwork prefab yard in Jebel Ali, the first step was to remove it and lift it up the first eight storeys to the podium. First of all, the metal had to get on to the podium. To do this, a giant crane has been called in from rental firm Al Faris. This Liebherr LTM 1500-8.1 has a 56m luffing jib and 165t counterweight, which provides an almost vertical boom setting. In simple terms, this means that it can lift almost straight up, because of the unusual design of the mast. In fact, this particular crane is rated at 500 metric tonnes, making it one of the strongest mobile units working anywhere today.

The crane lifted the steel section up to the top of the podium, but it needed to go another 50 meters higher, and into a position that no crane on the ground could reach. Instead, the developer turned to the local branch of Swiss firm VSL to raise the girders using a series of hydraulic jacks to ‘climb' the section into position. Pressure is put on each corner of the section with the pressurised units, and so the whole frame inches its way up inside the arch.

Lifitng

Hydraulics operator Peter Lehe explained: "Each jack is capable of lifting 45 tonnes and we used a series of these to get it to the desired height. Luckily, there were no major problems with this lift and we only need to get one other lintel in place on this job." Heavy lift manager David Gratteau added: "On many jobs the time of day that we move the steel is a factor. Often, people don't realise the amount the steel expands during the day, and this can make a difference."

He added that on this lift, precise measurements allowed for the variations though the day, which on a piece with this span can be several inches. Nevertheless, there must have been some nail-biting moments as a crowd of onlookers watch the steel creep into position.

Fortunately, after a tense twelve-hour session and as the sun set across the creek and in the shadow of the Burj, the section was finally in position, where it was bolted firmly in place while the sun set in the shadow of the  Like the rest of this build, the pace was not lightening-fast, but the quality is very high. If the hedge company ever relinquishes it's grip on the business tower, some very lucky firms, or just possibly the folks involved in a huge international non-governmental organization, will get to enjoy the view from this grade-A office every night.

What is hydraulic jacking?

Jack-up construction, or ‘Strand Jacking' is a method where concrete slabs and steelwork are lifted into position with computer-controlled hydraulic jacks.

Because the multiple jacks can be moved in unison and with great precision, heavy structures can be assembled at ground level (with increased safety and reduced cost) and then lifted into position, rather than having to be built in the air. Traditional cranes and other lifting methods cannot provide this level of precision.