STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

Fig. 3.62 Double-skin cable system with two sets of

cables separated by short compressive elements. This type

of arrangement is an alternative to single-skin systems

with anticlastic shapes.

Fig. 3.61 These cable networks can resist load from

different directions without undergoing gross changes in

form due to their having two sets of cables which are

curved in opposite directions to form an anticlastic

surface. They are each supported on arch-type compressive

elements. This type of cable system can also be supported

on an arrangement of masts (see Fig 1.13).

indeterminacy which is present, due, in part, to

the problem of predicting their final shape

under the action of a particular load. Analysis

by computer must frequently be supplemented

by model analysis. Constructional detailing

problems arise from the difficulty of providing

suitable end anchorages for the tension

members (one of the classic problems of

engineering) and from the need to construct

the structure in such a way that it can accom-

modate the small changes in geometry which

will occur in response to changes in load. This

normally requires the use of complicated joint

components, which must be specially

machined and are therefore expensive. The

cladding system also must be able to adjust

itself without damage to the movements which

will occur and this involves the design of joints

which are both weathertight and of adequate

strength, and which can accommodate

movement. Cladding systems tend therefore to

be fairly sophisticated and to have poor

durability. The consequences of all of these

complexities is that cable structures are very

expensive; they have been most often used for

high-prestige temporary buildings such as

exhibition halls.

support condition. Networks which are

supported on masts, for example (Fig. 1.13),

have a different geometry from those which are

continuously supported on arches. Variations

in geometry are also achieved by making use of

different cable arrangements (multi-layer

systems as opposed to single-layer systems,

for example). The choice of geometries

provided by the use of cable structures is

limited, however, because all of them must be

based on doubly-curved forms; all cable struc-

tures tend, therefore, to have a similar appear-

ance.

Cable structures are highly complex, both to

analyse and to construct. The difficulty in their

analysis results from the high degree of statical

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