Suspended stairs

Suspended stairs have already been alluded to in Asplund's Courthouse (referring back to Figures 2.7a and 2.7b). The concept usually relies on individual rod suspension or else a structural balustrade which suspends the treads along the bottom chord (Figures 7.6a-d).

A lattice structure can be made by connecting handrail, balustrade and undercarriage brackets; various patents exist that apply to both curving and straight flights. Welding balusters either as a horizontal frame (the hallmark of Marcel Breuer's designs) or as a trellis or vertical pattern are other alternatives. Suspension

Figure 7.5a Special stairs: Welded plate to form hollow profiles for newel and for cantilever treads: accommodation stairs at City Hall, Arnhem, General view wires can be used to secure wooden treads, one of the most minimal solutions being devised by Peter Moro at the former Hille showroom. The interior is now destroyed but is recalled to demonstrate the thesis 'least is most' with this example of slender detail (Figure 7.6d). The most interesting combination of trussed suspensions has been developed by Eva Jiricna and her engineer consultants. One of the best crafted stairs is the triple flight incorporated into the Joseph Store, Sloane Street (Figure 7.7a-c). The sculptural effect of this stair is closer to furniture with the engineering honed to the absolute minimum. The lightness of this eye-

Figure 7.5b Spiral stairs, Sainsbury Arts Centre, Anglia University, 1977, Architect: Foster and Partners

Compression fixings

Landing or tread trays

Steel \ Over sheathing tubular with anodized string aluminium

Figure 7'.5c Construction detail of balustrade and string, spiral stairs, Sainsbury Arts Centre

Figure 7.5d 'Nevada ' glass used in treads to Maison Clarté, Geneva, 1932, Architect: Le Corbusier
Figure 75e Ladder trusses carrying treads, Einstein Village, Princeton, USA, Architect: Marcel Breuer
Figure 7.6a Suspended stairs: Patented balustrade brackets (by kind permission of Ictoni Spiral Staircase Systems)
Figure 7.6b Suspended stairs: Balustrade trusses

Suspended stairs from floor above

Figure 7.6c Suspended stairs

Figure 7.6d Suspended stairs: Cable suspension, former Hille Showroom, London, 1963, Architect: Peter Moro

Figure 7.7b General view (see also Figure 319b)

Figure 7.7a Suspended stairs, Joseph Store, Sloane Street, London, 1989, Architect: Eva Jiricna, Engineer: Matthew Wells of Barton and Wells: Details: plan and section through typical tread

Figure 7'.7c Detail of structure

Figure 7.7a Suspended stairs, Joseph Store, Sloane Street, London, 1989, Architect: Eva Jiricna, Engineer: Matthew Wells of Barton and Wells: Details: plan and section through typical tread catcher is enhanced by glass treads and balustrading whilst the structure itself is an assembly of stretched cables, stainless rods and connectors providing a spider's web of supporting members. The art of constructing stairs when this level of skill is required is a combination of architectural and engineering input, hence the multiple credits to Eva Jiricna and Matthew Wells, now a partner with the consulting engineers Barton and Wells.

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