STRUCTURAL DESIGN FOR ARCHITECTURE

Steel structures

tecture has led to the extension of the visual
vocabulary of glass and steel. In the buildings
of architects such as the Coop Himmelblau
group (Fig. 2.1) and Behnisch (Fig. 2.2) this
most 'technical' of materials has been used in
the 'structure ignored' type of relationship to
support buildings with highly complex and
irregular geometries. It is the very high
strength of steel in both tension and compres-
sion and its ability to sustain high levels of
concentrated load which makes these free-form
networks of elements possible.
To sum up, the use of steel as the structural
material creates a range of aesthetic opportun-
ities for the designer of a building, any one of
which might provide the justification for its
selection. Firstly, steel provides a skeleton-frame
structure which allows the freedom in internal
planning and external treatment which is associ-
ated with buildings in which the walls are non-
structural. An extreme instance of this is the
building with transparent glass walls, but the
freedom can be exploited in other ways in the
treatment of both the interior and the exterior of
the building. Secondly, the great strength of
steel allows the creation of very slender struc-
tural elements. This, together with walls of light-
weight appearance, can be used to create a
feeling of lightness, openness and structural
elegance. Thirdly, the variety of precisely shaped
elements which steel makes possible and the
'technical' ambience which surrounds these
allows them to be used to convey symbolic
meaning. This possibility has so far been used in
a straightforward manner to express the idea of
technical progress. It could, of course, be used
ironically to convey a quite different meaning
and there is perhaps evidence that this is
happening in the architecture of Deconstruction.
Thus, the aesthetic of steel is the aesthetic
of the structural framework in which the
elements are slender and in which the problem
of providing support is solved in an apparently
effortless manner. It has normally also been
the aesthetic of the celebration of technology,
the machine and the production line as they
are symbolised by straight-edged forms,
regular and often rectilinear grids and overtly
machine-like detailing.

Fig. 3.11 Sears Tower, Chicago, USA, 1974. Skidmore,

Owings & Merrill, architects. The Sears tower, which was

for over two decades the tallest building in the world, has

a steel framework structure. [Photo: I. Boyd Whyte].

3.2.2 The technical performance of steel as

a structural material

3.2.2.1 Introduction

Steel is the strongest of the four commonly used

structural materials but has a strength-to-weight

ratio which is similar to that of timber (i.e. very 59