STRUCTURAL DESIGN FOR ARCHITECTURE

Steel structures

The basic elements of this type of structure
consist of a column unit (the 'trunk') which has
a rigid joint at its base, and a series of
cantilevering horizontal members (the
'branches'). In most cases this primary struc-
ture supports a secondary system of parallel
beams to which the roof cladding is attached.
The plan of each 'tree' unit can have any shape
but is usually square with plan dimensions in
the range 15 to 40 m. A number of units are
placed alongside one another to give a build-
ing of the required size. The advantage of the
system is that each unit is entirely independ-
ent structurally from its neighbours. This situa-
tion allows for simple extension or alteration
of the building, which is frequently the reason
for its adoption. This is also a form of
construction which lends itself to very fast
erection and the rapid production of a
weathertight envelope.
Two notable buildings which have been
constructed in this way in recent years are the
terminals at Stuttgart (Germany, Fig. 3.42) and
Stanstead (England) Airports. The Renault
Warehouse building at Swindon, England, by
Foster Associates (Fig. 2.6), and the Fleetguard

Fig. 3.43 Inmos Microprocessor Factory, Newport, Wales,

1982. Richard Rogers Partnership, architects; Anthony
      Hunt Associates, structural engineers. A mast-and-tie
      arrangement is used here to achieve a long span with a
      one-way-spanning structural system. [Photo: Alastair
      Hunter]

Factory at Quimper, France, have structural

arrangements which are a combination of the

structural tree system and the continuous two-

way-spanning frame. In each of these cases the

structural trees are not independent units.

In the Fleetguard Factory the sizes of the

horizontal elements were kept low by the use

of mast-and-tie systems. Mast-and-tie systems

can also be used in the context of one-way-

spanning frame arrangements. Examples of

this are the Inmos Factory, England by Richard

Rogers (Fig. 3.43) and the Ice Rink at Oxford,

England by Nicholas Grimshaw (Fig. 3.44). In

all of these cases the tie rods or cables serve

to provide a regular pattern of vertical support

for the horizontal elements and may be

regarded as substitutes for columns at these 87