STRUCTURAL DESIGN FOR ARCHITECTURE

Fig. 5.4 Basilica Nova, Rome, 4th

century CE. The architects and engineers

of Imperial Rome exploited the architec-

tural opportunities offered by the

buttressed, cross-vaulted hall to create

interiors of high architectural quality.

Structural Design for Architecture

support high-level vaults do not have to be

solid, however, and much of the architectural

expression of large vaulted hall structures has

been derived from the manner in which the

voiding of the walls was carried out.

The earliest of the large vaulted halls were

the basilicas and bath houses of Imperial

Rome. The evolution of the form is shown

diagrammatically in Fig. 5.3. The simplest form

of the building consisted of a barrel vault

supported on very thick, solid walls (Fig. 5.3a).

The efficiency of this structural arrangement is

low and is improved if voids are incorporated

into the walls (Fig. 5.3b). The solid areas

between the voids are, in effect, buttresses; the

voids are also vaulted. A logical progression

from this configuration is the adoption of a

cross-vault arrangement (Fig. 5.3c) as this

concentrates the load from the vault on to the

solid areas of the walls. It also creates flat

areas of wall above the original wallhead level

(i.e. in the zone of the vault) in which

clerestory lighting can be inserted.

The Basilica Nova (4th century CE) (Fig. 5.4)

and the main building of the Baths of Caracalla

(3rd century CE) are examples of this type of

structure. In both cases the structural armature

consisted of the vaulting system described

above, constructed in mass concrete, encased

in a thin skin of brickwork which served as

permanent formwork (Fig. 5.5). In both of these

examples this structural armature was clad in

150 marble to create a sumptuous interior.

Fig. 5.5 Detail of Basilica Nova, Rome, 4th century CE.

The largest interiors in Rome were constructed in unrein-

forced concrete, which was placed in a thin skin of brick-

work which acted as permanent formwork. The structural

carcass was then faced in marble to create a sumptuous

interior. The system of construction allowed very large-

scale buildings to be constructed economically.

The architectural opportunities offered by

the structural vocabulary of masonry were

therefore fully exploited by the Roman builders

who used them to create sequences of interior

spaces which varied in height, volume and

lighting intensity. Buildings of this type played

a significant role in the development of the

classical language of architecture. The stylistic