At 160 metres tall, the Capital Gate building may not be the tallest building in the Emirates, or even Abu Dhabi. But in a city famed for ambitious projects, it is by far the biggest architectural accomplishment. Tilting 18° westward, the Capital Gate has over four times as much lean as the Leaning Tower of Pisa. The 35 storey structure includes a cantilevered tea lounge and open air pool deck, as well as Abu Dhabi’s first Hyatt hotel, ‘The Hyatt@Capital Centre’. The tower’s external lighting minimises light pollution whilst optimising energy consumption, with a net of compact LED clusters integrated into the façade’s design. The Capital Gate sits on an intensive distribution of 490 piles, drilled 30 metres underground to accommodate the gravitational, wind and seismic forces caused by the building’s distinctive lean. Inter-connected with the thriving Abu Dhabi National Exhibition Centre, the tower is one of a group of 23 towers including branded hotels, commercial buildings, residential and serviced apartment complexes and developments for mixed use. The Capital gate was the first building in the world to use a pre-cambered core, with a built-in lean of 350 millimetres engineered to straighten with the addition of the upper floors. It is this same standard of innovation that has come to define the UAE; an oasis of intelligent design built in supposedly inhospitable conditions. We talked to RMJM Director Neil van der Veen about the challenges and rewards of working on one of the most infamous buildings in the world.
Where did the inspiration for the tower’s unique leaning design come from?
NV: With the Capital Centre district, the client was looking for a way to put in on the map. They wanted to expand the new business hub and give it an identity. It [the design] consisted of an exhibition centre and a mixed use development; those were the two primary components. With it came what was originally referred to as the feature tower, which was the building that would give it its identity.
The client had been grappling with the idea of turning the exhibitions halls into something iconic. But being a low rise structure, it wasn’t as feasible and there wouldn’t have been as much impact as putting a tower up. The brief was to create something that would give a completely unique identity to the district, but the brief further expanded to include giving Abu Dhabi something it had never seen before. So the brief started with almost trying to do the impossible.
We were worried that it wasn’t working, but science worked
What was the most exciting moment?
NV: The whole building was designed so that the higher you build it and the more weight sits on the top; the more the tower actually starts to lean more and more. So it had to be designed more vertically, so as you loaded it over it moved. That meant when if we started to build the bottom floors and the building continued to move, it could have ended up with serious cracks or other problems. This was a real engineering problem not often faced in architecture. One of the panels of the façade, (one of the outside ‘diamonds’ of the building) was brought in one evening and, when they tried to install it, it didn’t fit. Everything had been worked out to millimetre precision in 3D models, and yet it didn’t fit. That night they poured the next floor of concrete (because the region is so hot during the day, concrete is often poured at night). The next morning they put the panel back in and it fitted, so it was that kind of dynamic movement. We were worried that it wasn’t working, but science worked. It was that level of precision that we really got excited about during the construction phase.
How much did the building’s environment inform the design process?
NV: The lower half of the building is the office tower and the upper half is the hotel. The ‘splash canopy’ of the building starts at the grandstand end and covers the drop off to the hotel, rising up to the lower half of the building. It screens the sun from the glass façade of the office building and the grandstand seating below. In the upper half there is a concrete core, on the sunny side, so the screen isn’t really required here. The splash canopy is actually one of the most sustainable parts of the form. The design features a lot of other sustainable technology, but this was the most passive system we introduced to keep the harsh sun away from the glass.
The UAE stands as a testament to man’s ability to adapt to any climate, what do you think the Capital gate represents?
NV: I think it was more like the spirit of the time where Abu Dhabi was showing “we can do anything, and we can do even more than anything”. We wanted to push the boundaries and we wanted to show the world what we are capable of. And that’s what it stands for and that’s why it has also become an icon for the city. It’s used on literature, brochures and tourist information.
Was there any point where you doubted the design was truly possible?
NV: There were very few times when we didn’t. We went to the first meeting and said to the client “You wanted the impossible, here’s the impossible!” Then it was a case of saying “Alright now, what should we do?” We had to continue and keep exploring it. And then slowly people start to think “Oh, we may be able to do this.” Then you bring the engineers on board and they start to say “Oh god no, I don’t think this is possible.” So it was this continual cycle of doubt. Generally the feeling in the office was that this was probably a concept that wouldn’t go ahead, as so many concept designs at this stage didn’t. It just continued to surprise everyone as it moved forward. As you say, it is a pioneering structure, and I think that really is one of the things that it focused on. Looking at the structural engineering behind something like this, it’s opened up new avenues of doing things, and while it is a striking architectural piece, a lot of the innovation was focused around the structure of the building.
There were very few times when we didn’t doubt that it was possible
Do you think the UAE’s rapid development will cause the country problems as it continues to expand?
NV: Definitely there are issues in the UAE’s continuing growth in terms of natural resources. However, at the same time its economic existence relies on it expanding and becoming a critical mass, so it has a post-oil life. There will be problems, but we are definitely not alone in those problems. There are sustainable cities, like Masdar, also in Abu Dhabi. Masdar’s been being developed for a long time, and it’s touted as the one of the most sustainable communities in the world. Again that’s Abu Dhabi trying to push the realms of what can be done. I think Dubai tends to do it in the flashiest way, in terms of the tallest, the biggest, and those types of thoughts; whereas in Abu Dhabi, being the capital, things tend to be done more conservatively. Abu Dhabi is very focused on things like cultural development and sustainability and what it’s going to be doing in twenty or thirty years’ time. Abu Dhabi has a slightly different focus to Dubai. But they are both very much trying to show what they can do and keep themselves on the world stage.
The Capital Gate opened to widespread critical acclaim on December 21st 2011. The unique design and innovative technology used in its construction earned the tower numerous awards, including Best Overall Project and the best Commercial Project at the 2011 Dubai Cityscape Awards. Prior to opening, the Guinness Book of Records officially certified the tower as being the furthest leaning man-made structure in the world.