Early forms

The earliest forms of concrete stairs are Roman where concrete was placed over brick vaulting to support ramps or steps such as in the construction of the Colosseum (Figure 8.1a). The introduction of filler joist flooring in the eighteenth century, with wrought-iron beams infilled by brick arches, was adapted to staircases can-tilevered off masonry walls (Figure 8.1b).

The early use of concrete in the twentieth century was found in composite forms of building. In the case of stairs, steel joists often formed the stringers to reinforced concrete infilling (Figure 8.1c). Nervi, one of the finest concrete engineers, designed a minimum double-spiral stair for the Florence Sports Stadium (Figure 8.1 d). His avant-garde approach to reinforcement design is not without problems, loss of cover to the exposed main beams having led to extensive repairs.

Figure 8.1a Brick vaults which supported steps at the Colosseum, ad 70-82

Jack arches for landings

Figure 8.1b Filler joist stairs constructed with steel beams and brick vaults overlaid with rendering

Jack arches for landings

Figure 8.1b Filler joist stairs constructed with steel beams and brick vaults overlaid with rendering

Both Frank Lloyd Wright and Le Corbusier were enthusiastic exponents of reinforced concrete and realized stair designs that captured the plastic qualities of the material. The long curving ramp at the Guggenheim Museum (refer back to Figure 2.25a and 2.25b) is perhaps the most celebrated cantilevered form. Le Corbusier's designs from the heroic period (1920-30) transformed ramps and stairs into sculptured volumes that interpenetrated the floor spaces of his major buildings. The poetic geometry given to the circulation elements within the Villa Savoye (referring back to Figure 4.11) is amplified in the palatial volumes made for grand projects such as the League of Nations or the Centrosoyus Building, Moscow. The staircase structure and its relation to the plan in the Goldfinger House in Hampstead is a microcosm of the Corbusian principles, revealing the key to employing monolithic concrete to form both column and curving slab within a single stair (refer back to Figure 4.12).

Figure 8.1c Textbook example of early reinforced concrete stairs using composite construction with steelwork
Figure 8. Id Confident use of reinforced concrete structure in stairs, Florence Stadium, 1932, Engineer: Pier Luigi Nervi
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