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Fantastic forms realised through digita design

STEEL - Iconic buildings and bridges springing up around the world demonstrate a new confidence with steel, and the excitement is only just beginning, Dominic Pask tells Emma Crates

DOMINIC Pask has one of those jobs that schoolboys dream about. A specialist in architectural structures, he gets to sketch fantastically wavy roofs, bridges with impossibly elegant curves and towers that shoot to the sky like rockets.

The only difference is, Mr Pask gets to turn his felt-tipped doodles into reality.

The Atkins associate is currently jetting between the UK and Dubai as he works on the latest landmark for the city - the Trump Tower. The structure, to be built on the 'trunk' of the emirate's man-made Palm Jumeirah island, will consist of two towers straddling a monorail. They will be connected at the apex with a glass and steel structure apparently floating 200 m above ground level. The concept is as breathtaking as the views it will eventually afford.

In the past two or three years architects have been pushing the boundar ies of design by creat ing more f luid shapes, says Mr Pask. As one of Atkins' design heads, specialising in steelwork, glass walls and bridges, he is one of those at the vanguard of the change.

'At Atkins we're trying to raise the standard of design generally, ' he says. 'Fabricators have been just about keeping up with designers and the technology is just about there.'

Concrete, of course, has for decades been used for inspirational buildings. Italian architect Pier Luigi Nervi, who died in 1979 was an early pioneer of curved forms.

'We have been able to use concrete creatively for years. But we've only just got the technology to do these kind of shapes in steel, ' comments Mr Pask.

Previously, if you wanted to work in steel, curved elements would have to be worked on in a painstaking way, crafted as if they were sculptures. Now, innovation in IT and fabrication equipment is allowing more avant garde shapes to be manufactured as structural elements.

You can also achieve previously unheard-of precision through increasingly sophisticated computer programmes, says Mr Pask.

This enables three-dimensional shapes to be drawn electronically, which the programme can then flatten out into life-size cutting patterns, which are then cut using computercontrolled machinery.

It is, he says, having a particularly noticeable influence on bridge design. But while IT is creating new architectural possibilities, this inevitably this comes with a price tag, which clients sometimes balk at.

Richard Rogers' stunning footbridge, Neptune's Way, which won the design competition for Glasgow City Council, will sadly never make it over the river Clyde because the original budget exploded from £40 million to £60 million. Although the design was a big hit with the public, the council is now retendering the bridge as a design and build contract with a price tag of just £6 million.

But Mr Pask, who spent a long time working on the concept with Atkins, believes that, had it gone ahead, Neptune's Way - which consisted of three main elements: a curved box section steel deck, a 30 m-high steel arch, and tie-back cables - would have been a further development of the similarly shaped Gateshead Millennium Bridge - nicknamed the Blinking Eye - by Wilkinson Eyre.

'You are beginning to see a more fluid shape with the Gateshead Bridge, although it was only partly curved. Most of the sections were flat, ' says Mr Pask. Had it gone ahead, Richard Roger Partnership's Neptune's Way design would have taken a further step by introducing three curved corners which changed in shape and section along the length of the arch.

But Atkins has had more luck with the 70 m-span Usk Bridge in Newport. The foot and cycle bridge, which features two massive A-frame masts, ha become a local landmark since opening in September.

When work ing on the br idge details, fabr icator Rowecord was greatly helped by increasing advances in IT, and used the Tekla Structures programme.

'Previously you would only have been able to work on tiny parts of the project. Now computers have got enough memory and large enough graphics capacity to handle th is in one go, ' says Mr Pask. 'It was a huge programme. When you were producing drawings you could pull off individual plates. The computer then picked out the shapes and they could be cut out.

Each one was unique and cut in a unique way.'

Ian Hoppe, bridges director at Rowecord agrees. 'The 3D drawing package made it possible to calculate centres of gravity automatically - we were able to plan our lifts with accuracy'.

He adds that the company has been using the software package for around 10 years, but developments in that time have transformed the way the company works.

The design team can now view the inside of the structural elements virtually.

'The Usk Bridge has a strong visual impact, but the complicated stuff is hidden behind the smooth skin, ' comments Mr Hoppe. 'We were able to filter out the external elements to assess the internal workings.'

The advent of induction bending has also helped steel enthusiasts. It allows t ighter radii, to be produced , without a corresponding loss of thickness of the steel. 'We're just getting going with more f luid curved steel, and I think we'll start playing round more with it, ' says Mr Pask.

Two of his current projects, the Trump Tower and a mixed use scheme in Islamabad in Pakistan (left and above) demonstrate the confidence architects now have about working with steel internationally. But the UK is also feeling the effects.

'In the past three years there has been a huge requirement for signature bridges, agrees Mr Hoppe. 'Everyone seems to be launching design competitions these days. Steel, he believes, gives more architectural scope for creativity.

'Most of the work can be carried out off-site, and the erection periods tend to be shorter, ' he adds. 'Some people think that the bridge market may shrink slightly next year. But I don't subscribe to that view, with all the work coming across my desk.'

So, with fingers crossed, the UK could be moving into a brave new era of steel architecture. But it all depends on the clients, of course.

Trump International Hotel and Tower, Dubai

WHEN thinking big, concrete is currently Dubai's material of choice. 'They are so used to working with it, ' says Mr Pask.

'And they can work with it incredibly quickly and cheaply.'

So, true to form, the iconic twin towers currently under design for the Trump Tower in Dubai will predominantly be constructed of concrete.

At 255 m, the 60-storey structure will act as a gateway to the Palm Jumeirah island.

The towers are different sizes - or 'asymmetric halves'.

But at the top of the structure, beyond 200 m, things get exciting. The towers are joined by a steel and glass structure.

As the towers are quite slender, Mr Pask says that joining them at this point helps with the stability, although the advantages are mainly for wind loading.

'There are some seismic loads but they're not that serious, ' he adds.

The extension will consist of a 'large and simple' steel megastructure, set inside glass walls, with delicate steelwork supporting the glass.

'From the ground, you'll see the big structure, but the delicate glass and steel will disappear from view at ground level, ' says Mr Pask.

One of his challenges is working out how to install the steelwork and also a strategy for getting and replacing the glass. 'If a piece of glass gets broken up top, and you don't have a crane out there, you'll have to find some way of replacing it, ' he comments.

Far down below in the lobby area, there is more scope of using steel in a different way. The mezzanine level, with bars and seating areas is likely to be a series of giant stepping stones, which will look like pebbles from above, but be supported on steel stalks like mushrooms from below.

'This is where the steelwork will come in. Because the pebbles will be sitting on top of another structure, concrete is going to be totally unsuitable, ' says Mr Pask.

Islamabad

THIS wavy-roofed, mixed-use scheme, currently at concept stage, is all the more challenging because it is in an active earthquake zone.

Below the undulating roof will be a shopping mall, pierced by residential towers. The wave extends up into a sheer spike which will house a hotel. To add to the complication a restaurant, roughly 18 m in diameter, will cantilever out of the top of the hotel. It was formerly planned to be a helicopter pad but its function has since been reassigned.

'This restaurant presents ser ious seism ic considerations, ' says Mr Pask.