Steelworks with a clever twist
It is not always easy to be innovative. Too often budget constraints, common sense and concerns about reliability mean that the most sensible solution is the simplest and best understood. How nice then when innovation is what the project is all about.
At the Glasgow Science Centre (previous pages) this is immediately visible externally.
At Magna, the renaissance of the old Templeborough steelworks complex between Sheffield and Rotherham, the level of innovation is not immediately visible. But in fact the project, which opens this spring, is one of the more imaginative Lottery-funded projects.
Magna deserves to be called a complex because of its sheer scale. The robust shell, which is being given a minimal brush-up, is so massive that the attractions within it, including the four elemental pavilions, seem small. Actually the pavilions are substantial, with all the requirements of a 'proper' building bar two - they do not have to keep the rain out or resist wind loads. But since they will be heated islands within an unheated space, they must have proper levels of insulation.
The water pavilion, about 40m long and 18m wide, is at ground level, so that it can transfer the load of the tanks of water inside it. Architect Wilkinson Eyre decided that its innovative energy should focus on the cladding. Chris Wilkinson's original concept was to echo the kind of metal water container found in the desert. Since the main circulation route at Magna is above this pavilion, the appearance of the roof was vital. The architect was also interested in having a reflective surface to contrast with the rusty redundant furnace and to take maximum advantage of the 'flames' from the nearby fire pavilion.
Visually the result is relatively simple - a shiny, rounded pavilion, glazed at the ends, a smooth intrusion into the rough aesthetic of the old steelworks. But this has been achieved through a design of considerable complexity.
The form started off from the slab on which the pavilion sits. One early decision by Wilkinson Eyre was that there should be no piling. The slabs were substantial, to take the weight of the steelmaking equipment, but beneath lies unreliable ground. With budgets limited and fear that any disturbance of the ground below could create a bottomless pit, extra support was not an option. Therefore the pavilion had to be positioned where the slab could offer maximum support.
But this led to it sitting on what project architect Marc Barron describes as 'a fault line' in the original steelworks building.
Because the site slopes down to the River Don, a step in level of 1.4m runs through the building along its length. The water pavilion straddles this step. 'It generated a form of asymmetry that we thought was very interesting, ' says Barron. 'The building is formed from two ellipses joined together which is a spiral. Then we distorted the spiral, and found that we could still clad easily by following the spiral. But we hadn't seen that form done before.'
If you find that concept difficult to grasp, you aren't the only one. Wilkinson Eyre has had lengthy conversations with engineers about whether or not this design involves double curvature. The answer is it does not.
The form of the building gave Wilkinson Eyre another analogy. It sees in the distorted elongated ellipse a crashing wave. Having established this form and the way it would be clad, it then had to deal with the structure. 'We would have liked to have carried the cladding spiral through to the local extreme of the structure, ' says Barron, 'but there is no point in putting the structure on a spiral because it increases the span.'
The structure is therefore orthogonal to the building section, formed of a series of ribs at 3m centres. Each rib was formed in three sections, spliced at the one-third points. The top section was rolled to create a bent universal beam. The side sections, however, had to be fabricated because of the tightness of the radius. The ribs are founded into a beam on the ground. Braces in the floor structure take out the lateral thrust.
This structure repeats to either end of the building. There the architect pulls out the ends of the spiral which called for the largest made size of circular section, with a wall thickness of 25mm. Angle Ring, which acted as a subcontractor to steel fabricator Billington Modern Structures, produced these elements. 'They are at the forefront of the technology of bending, ' says Barron. Angle Ring analysed the form by computer and then bent the CHS in several sections. Then it twisted the central axis before welding the sections together. This curved element was delivered in three pieces and welded on site.
The elements that sit behind the end elements are not 'normal' either. They are circular hollow sections, not twisted but skewed at an angle of 22.3degrees to the orthogonal section. The glazed ends sit within this skewed plane, clipped around the curve.
Standard technology is then used for the glazed doors that sit within the walls.
The cladding also alters at the ends of the building. Between the two skewed sets of ribs it comprises 0.9mm thick stainless steel cladding continuously supported by a structural deck. At the ends, where the stresses are greater, the architect has instead used a 5mm thick steel plate. This effectively creates a canopy over the entrance which, although not needed for shelter, gives a sense of arrival.
Internally, visitors pass through the building in a U. As they turn back they experience a change in level which, at about 0.7m, is a reduced version of the 'fault line'.
The space is divided into dry and wet areas and fitting out is nearing completion for the opening next month.
Magna is being promoted as the UK's 'first science adventure centre' that will provide visitors with 'a unique and unforgettable experience'. For the discerning visitor, much of this will come from the contrast between the magnificent arrested decay of the steelworks and the imaginative pavilions.