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Dreaming spires for the towering giants?

2000 & Beyond; The skyscrapers of the future may dwarf their 20th century counterparts but are they a realistic proposition or the stuff of fantasy? Aaron Morby reports

SKYSCRAPERS are as much a symbol of the 20th century as the car, television or computer.

They characterise modern cities, stand for financial power and prosperity, and earn their engineers and architects distinction.

So it is strange to think that the record for the world's tallest building has edged up by just 10 m in the 26 years since the 442-m Sears Tower in Chicago was built.

Yet even the Sears and the twin-towered Petronas building in Malaysia, which is the current record holder, are dwarfed by the challenging vision of famous American architect Frank Lloyd Wright, who 40 years' ago proposed a one-mile-high tower. His needle-like edifice, called the Illinois, was designed to accommodate 100,000 people with enough office space to house an entire city government and still have room to spare.

Even then, Mr Wright maintained that the engineering capability to build his 1,609 m giant existed.

While this may have been the case, it would have been a building that few people, by today's standards, would tolerate working or living in. To meet modern expectations, the main challenge for anyone designing tall buildings is how to move people up and down effectively.

Andy Miller, director of Foster and Partners, explains: 'We have been stuck at around 450 m because of the traction motor lift system.'

As soon as buildings surpass this height, the number of lift shafts and hoisting machines needed to service the building start consuming all the ground floor lobby space.

One way around this problem has been the creation of skylobbies, as used in the Petronas Towers. Here a lift takes passengers to a high-level lobby and then another lift is used to reach the top.

The Japanese have taken another approach, developing double-decker lifts to raise passenger-carrying capacity.

But advances in lift technology promise a revolution that could see construction of an awesome new generation of buildings.

One manufacturer is developing a lift system where cars will move horizontally before being picked up by steel-framed cages that raise the cars between sections of the building. This effectively reduces the number of lift shafts that are needed.

Another system, which many engineers believe is likely to be the most successful, effectively works on a vertical monorail system. This cuts out the need for space-consuming cables, counterbalances and winching engines.

A prototype has been built but has yet to be tested in a real building environment.

John Brazier, associate director of Arup, is optimistic about the prospects of a real step change in the height of buildings: 'If the demand for taller buildings is there, the basic structural systems are in place.

'Active systems to dampen building vibration using concrete masses on rollers means thatwind loading is no longer a big problem.'

Mr Brazier predicts that 'in the next 10 years, we'll definitely see buildings in the 600 m to 700 m range'.

Mr Miller believes the next generation of towers will soar to even greater heights. He says: 'If the will is there we could see something 800 m tall within the next 10 years.' In fact, modern technology will, in theory, allow buildings to reach heights of 1 km.

Foster and Partners is looking to make its mark in this new realm and has worked up a design for a tower reaching 800 m. Thebuild-ing is a slender cone shape with a helical superstructure on the exterior which helps to reduce wind loading.

Called the Tokyo Millennium Tower, the structure was planned to rise up from the sea in Tokyo bay but the project fell victimto the Japanese banking crisis.

Building of this scale would require a truly global effort when it came to a procurement.

'With approaching 400,000 tonnes of structural steel for instance, most materials would need to be sourced internationally,' explains Mr Miller. 'Japan's industry would be hard-pressed to meet demand.'

Construction time alone was estimated at eight years for the Tokyo tower, although it is now believed this can be reduced to five or six years using modern procurement techniques.

But it is the old problem offinance that poses the biggest challenge for those looking to construct the next generation of giant skyscrapers.

This was highlighted recently by the Far East economic crisis, which stopped two potential record holders in their tracks.

Construction of Shanghai's Mori building, engineered by Ove Arup, was abandoned after more than 2,000 piles had been sunk. A similar fate befell Taiwan's attempt to build the world's tallest building, the Taipei Financial Centre.

Now both projects are on hold pending new financing arrangements, due to be agreed this year. But they could yet be delayed further and redesigned as Chicago in the US makes its move to build a taller building in South Dearborn.

Funding such buildings is made all the more difficult by long planning and construction times. Grandiose plans for skyscrapers are invariably conceived when economies are buoyant and developers are optimistic. Yet by the time they come close to realisation, property markets have often changed.

If this was not enough to make bankers and tycoons think twice, there is a growing body of opinion that says the era of the skyscraper is drawing to a close as modern city development moves inexorably towards greater sustainability.

Critics argue tall buildings are often not economically viable, socially productive or environmentally friendly. They say that allfuture buildings should be constructed to reflect the efficient use of materials and be less reliant on services that use precious fuel - such as lifts, air conditioning, lighting, fire services, exhausts and water pumps

Then there is the curse that appears to haunt tall buildings and the economies that fund them. Each time a new record is set, an economic crisis centring on that region has quickly ensued. The US boom of the '20s and '30s, culminating in the construction of Empire State Building in New York, ended with the Great Depression. The same happened to Malaysia almost as soon as the Petronas Towers were finished.

Financial fears aside, architects and engineers are striving to demonstrate the green credentials of their buildings and many have made use of wind power in putative designs.

But there is growing belief that the current climate for tall buildings is limited in Europe and the US.

Mr Miller predicts: 'If they are to be built the chances are it will be in South-East Asia. This is where you see a huge influx of people from rural regions to the cities where there is invariably pressure on land. If you can create a lung of green in a busy city with a tower, then the environment is being really improved.'