flat-slab structure was particularly notable
(Fig. 4.3 ). All of these early pioneers were
concerned principally with the application of
reinforced concrete framing systems to indus-
trial buildings.
In the late nineteenth century reinforced
concrete was a 'new' structural material,
capable of producing durable and fire-proof
skeleton frameworks and therefore buildings
with open interiors free from structural walls. It
arrived on the architectural scene at a time
when the precursors of the Modern Movement
were exploring the possibilities of creating a
new architectural language which would be
appropriate for the twentieth-century world.
These architects were anxious to make use of
the new materials which industry was produ-
cing and the most innovative of them were not
slow to appreciate the potential of reinforced
concrete.
Among the earliest of designers to under-
stand the purely architectural qualities of the
new material was August Perret. In the apart-
ment block at 25 bis Rue Franklin, Paris, 1902
(Fig. 4.4), the adoption of a reinforced concrete
frame structure was used to produce an open-
plan interior with light non-loadbearing parti-
tion walls. Large areas of glazing were a feature
of the exterior and the reinforced concrete
columns of the building, although not actually
exposed (a tile cladding system was used),
were expressed on the facade. The later garage
at 51 Rue de Ponthieu by Perret was also
based on reinforced concrete and in this build-
ing the concrete framework was left entirely
exposed, apart from a thin layer of paint. These
buildings were very important precursors of the
Modern Movement. An important aspect of
their novelty was the role played by the struc-
ture in liberating the organisation of space
from the tyranny of the loadbearing wall. This
was exploited by Perret in his design for the
Rue Franklin flats, producing a version of the
Paris apartment in which a new free-flowing
space could be enjoyed. The other significant
aspect was the re-establishment of structure,
and in particular the column, as a part of the
architectural expression, something which had
not happened since the eclipse of Neo-
101Fig. 4.3 Cross-section through five-storey flat-slab struc-
ture by Robert Maillart, c. 1912. Flat-slab systems, which
are sophisticated two-way-spanning structures which
derive much of their strength from the high degree of
structural continuity which is present, were developed
surprisingly early in the history of reinforced concrete
construction. Because there are no downstand beams the
system allows a very economical use to be made of both
material and labour. Local thickening is required in the
vicinity of the columns, where shear forces are high. This is
accomplished by the use of 'mushroom' column heads.
Reinforced concrete structures