bases. If ribs are inclined from the vertical or curved in elevation they
may be propped by other ribs to achieve equilibrium, as in the case of a
ribbed dome. Ribbed structures generally enclose single volumes rather
than multi-storey construction. By restricting the height of these struc-
tures effectively to a single storey, albeit very high, designers avoid
potentially compromising a pure architectural language of ribs with
additional interior load-bearing structure.
Ribs visually dominate each of the four structurally independent Licorne
football stadium perimeter walls at Amiens (Fig. 3.13). Elegantly curved
and tapered, the ribs shelter the spectators and accentuate a sense of
enclosure. The combination of widely spaced ribs and glazing provides
an unusually high degree of transparency and openness – daylight is max-
imized, spectators are more acutely aware than usual that the game is
being played outside, and they can enjoy the surrounding townscape.
A prop near to the base of each rib provides its base-fixity and stability
in the transverse direction. Unusually configured moment-resisting
frames within the ribbed surface resist longitudinal loads. In these frames
the ribs function as columns, and the horizontal tubes or girts, rigidly
connected at 1 m spacing up the ribs, as beams (Fig. 3.14). The integra-
tion of girts with ribs to form these multi-bay frames avoids the need
for a more common and economical form of resistance, such as diago-
nal bracing whose geometry would clash with an otherwise regular
orthogonal pattern of ribs and girts.
A similar combination of primary structural ribs and secondary horizontal
tubes defines the architectural form of the Reichstag Cupola, Berlin
(Fig. 3.15). In this case, ribs lean against each other via a crowning com-
pression ring. An internal double-helical ramp structure supported off28 STRUCTURE AS ARCHITECTURE
▲ 3.11 Hall 26, Trade Fair, Hanover, Germany, Herzog + Partner,
- Three catenaries span between masts.
▲ 3.12 Exposed steel catenary members connect to an
interior mast.