STRUCTURAL DESIGN FOR ARCHITECTURE

Structure and architecture

concrete than in steel (Figs 1.17 and 4.20). The
shapes of the elements are usually, however,
more crude at a detailed level.
Masonry is the term for a range of materials
which have the common characteristic that
they consist of solid elements (bricks, stones,
concrete blocks, clay tiles) which are bedded in
mortar to form piers and walls. A range of
other materials with similar physical properties
to masonry, such as various forms of dried or
baked earth, are suitable for the same types of
structural configuration.
The principal physical properties of these
materials are moderate compressive strength,
relatively good physical and chemical durabil-
ity and good performance in fire. Very signifi-
cant properties are brittleness and low tensile
strength. The last of these, in particular, has a
profound effect on the structural forms for
which masonry is suitable. Lack of tensile
strength means that bending-type load of
significant magnitude cannot be resisted so
that masonry structural elements must be
subjected principally to axial compression

Fig. 1.18 Casa Pfaffli, Lugano, Switzerland, 1980-81.

Mario Botta, architect. The structure of this building

consists of loadbearing masonry walls supporting

reinforced concrete horizontal structural elements. [Photo:

E. &F. McLachlan]

only. They can be used as walls, piers, arches,

vaults and domes but not as slab-type horizon-

tally spanning elements. When used as walls,

they must be supported laterally at regular

intervals due to their inability to withstand

out-of-plane bending loads such as might

occur due to the effect of wind pressure.

Masonry is therefore used in the loadbear-

ing-wall form of structure (Fig. 1.18) to produce

multi-cellular buildings in which the principal

walls are continuous through all levels, giving

similar arrangements of spaces on every

storey. The horizontal elements in such build-

ings are normally of timber or reinforced

concrete but may be of steel. Structural con-

tinuity between these elements and the

supporting masonry walls is difficult to achieve

and the internal forces in the structural 15