STRUCTURAL DESIGN FOR ARCHITECTURE

Structure and architecture

1.3.2 Vaults and domes
Vaults and domes are structure types in which
the dominant feature is an upwards curvature
towards the dominant, downward-acting gravi-
tational load (Fig. 1.11). They belong to a class
of structure in which the internal forces are
predominantly axial rather than of the bending
type,^2 and, in the case of vaults and domes,
this internal force is compressive. They are
therefore normally constructed in materials
which perform well in compression, such as
masonry or concrete.
The axial-compressive-stress-only condition
which is associated with vaults and domes has
two important consequences. First, it allows

2 See Macdonald, Structure and Architecture, Chapter 4 for a

classification of structure types. The principles are

summarised here in Appendix 1.

Fig. 1.11 TGV Station, Lyon-Satolas, France 1989-94,

Santiago Calatrava, architect/engineer. A vaulted structure

in reinforced concrete is used here to achieve a relatively

long span. [Photo: E. & F. McLachlan]

large horizontal spans to be achieved with

materials, such as masonry or unreinforced

concrete, which have little tensile strength (Fig.

5.4): large-span interiors can be created in

masonry only by the use of domed or vaulted

structures. This was the principal reason for

the use of this type of arrangement prior to the

invention of modern materials such as steel

and reinforced concrete which allow large

spans to be achieved with post-and-beam

forms due to their ability to resist bending

effectively.

Secondly, and perhaps more importantly for

the buildings of today, it allows loads to be

resisted with much greater structural efficiency

than is possible where bending is the principal 9