The initial brief from the client called for a structure that would prevent people from falling down the public stairwell in Victoria University’s Rankine Brown Library. The client did not wish to have a structure that would appear like a ‘cage’. The Rankine Brown building was built in the 1960’s, with the north stairwell being a ten storey stairwell formed from concrete around a central ‘well’ area giving vertiginous views downwards – accentuated by the low balustrades which were built to the building codes of a different era. The new design takes a sculptural approach – filling the void with a sculptural lantern to make the stairwell safe – rather than the obvious solution of making a ‘cage’ around the edge of the stair structure. [More information…]
The key concept of the design was to take an observer’s thought away from the primary purpose of “fall-prevention”; the idea of the sculptural lantern being an object to observe and walk around, which by taking your attention in this way then subtly removes the temptation to jump or throw objects down the gaping shaft. The second key concept was not to “target harden.” That is; the idea of building something to withstand all possible damage that people might inflict, and in the process encouraging them to test that strength. Instead, the idea being that by designing something that becomes a valuable feature, although it may be less bullet-proof it encourages pride and care. By not fixing structure to the stairs and landings we avoided making a cage that is formed by the surrounding structure. We looked at many types of intervention and came to the solution of a tube in a square hole (the stair void), which would allow views to other landings and some limited views down the entire shaft in the corners, so that the height could still be perceived a little, but with the actual potential to fall removed, and the sense of a drop down the yawning 10 storey shaft greatly reduced. By making the tube from a translucent material (PLEXIGLAS® Multi-Skin-Sheet SDP 16) it became a light sculpture in the stairwell. The selection of a translucent (instead of clear) PLEXIGLAS® reinforces the simple form. The fabrication of the translucent tube from PLEXIGLAS® also allowed it to be lightweight and consequently need less structure for support. This in turn allowed it be cheaper, require less scaffolding to put in place, be faster to build and have less impact on the operation of the library which is in use all year around, and at all hours. A clip system was designed to hold in place vertical slats formed from plastic, which are the same size and can be replaced if required. One clip was designed and fabricated for all the connections. The cost is in the mould and so having extra clips made in the future as replacements or for other stairs can be cheaply done. The slats are clipped on to steel wires which are tensioned to the entire height of the stairwell. The plastic panels selected are highly durable but there remains the potential for damage. Given this, the design is based on the need to occasionally replace a panel and so the cut of the panels was designed to be simple and not require much machining, and to cover this possibility spare panels were ordered when the project was built. Using flood lights, one located at the ground and one at the top floor ceiling, allows the lantern to glow pleasantly. The light fittings were chosen after testing by a photometric computer simulation to provide uniform lighting. The circle of wires supporting the slats also forms a protective barrier around the light fitting so that no one will be burnt by the heat of the light.
Tennent & Brown
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PLEXIGLAS® Stegplatte weiss W1621
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