How to tell the right time on an 80,000-tonne clock

Following the announcement of Time Residences last week, Nick Cooper from Bennett Associates talks to Construction Week on how exactly he plans to get an 80,000 tonne building to rotate

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By  Christopher Sell Published  December 9, 2006

|~|149int200.gif|~|Despite the engineering challenges ahead, Cooper is confident that Time Residences will fulfill its potential as the world’s first fully rotating tower.|~|What is your role on the Time Residences project?

My role is to turn it. And I have to let everybody know what they have to do to get it to turn. I am not involved in the actual construction.

I have a base design with a very solid foundation, and off that, the building. Between the two we have got this bearing system. I am using a technique that was employed by the Egyptians to lift and move heavy loads, and quite frankly it’s the right technique to use because of its simplicity.

Is there a precedent you have modelled this on?

We are using technology found on submarines; the seals, the bearing materials, we are using their concepts. Brunel lifted SS Great Britain using the same methods.
When you have 80,000 tonnes sitting on something – this is where the power of water comes in. If you imagine a super tanker in the sea, it floats, but on land it is immovable. We are using that sort of thought process. Its going to be moistened, with friction pads to keep the stability. And we need to find the order of its effective friction force of 1,000 tonnes.

Its very simple when you break it down. A lot of people would say: ‘I want a bearing that takes a 1,000 tonnes’ – now nobody has made a bearing of that size. Jodrell Bank Observatory in the UK only weighs 4,000 tonnes and that has one of the biggest bearings in the world.

What technological methodology are you using for this?

It’s putting together the simple things in the right order. Effectively, what you do is have one base on top of another base and there is a slither in the middle, which has everything in it. The driving mechanism is the key; it has to be absolutely right.

When it comes to stability and safety of the structure, obviously everybody is worried about the building toppling, but as long as you have your reaction dampers, you still have the inherent stability over a seismic earthquake. In fact, if you have a break in a structure due to a seismic event, it creates a safer building, because it allows the movement from the bottom and top to stay stationary, so you do gain something.

How did you come to be involved with this project?

We have a great background in movement. We did the Channel Tunnel, resolved the movement on the Gateshead Millennium Bridge and did the Falkirk Wheel. We also worked on most of the other Millennium bridges.

The big engineering companies are so conservative and afraid of risk. They are trying to off-load risk with insurance all the time. The bigger companies are using us because we are not afraid to say yes. Everyone wants a challenge, don’t they?

So what then are the main challenges in this project?

Reliability. Because it’s a timepiece, you don’t want it to stop. Every hour it will move for five minutes. So when the bell chimes, it will move. The fundamental techniques don’t differ – we are giving them the foundation, and they can build their building as long as we have covered all the seismic aspects required.

People often start these jobs saying: ‘How we are going to go about it?’ It’s about getting the fundamentals sorted. I always think the genius is the guy who says can you do it, not the person who actually delivers it.

Have you conducted tests for this building?

We have done most of it in the UK, where we have had some of the major laboratories testing this. But it is not complex testing, because the components we are using are readily available. We just need to prove certain properties, and satisfy certain criteria and building safety regulations. So all the stresses and the bearing pad systems have to cope with the same factors as any normal building. The other factor is seismic vibration – this was the starting point. On the first day I said the first thing we have to worry about is, not what it weighs, but what the seismic results are. These then set the diameter and the stability.

How will the building incorporate environmental features?

We are going to make sure the power is delivered by solar energy. We are going to take solar power, store it and use it, because its hypocritical to say we are developing a building that turns and then use electricity to do it. I have 20 drives turning this thing and each pulls 2.5kW. Each drive is one toaster, and the system uses the equivalent to 20 toasters for each five-minute movement.||**||

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