STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

and reinforced concrete, has made possible

the creation of quite different plan-forms in

masonry, however. The 'brick country house

project' of 1923-24 by Mies van der Rohe may

serve as an example (Fig. 5.19). Here an irregu-

lar pattern of loadbearing walls was adopted to

accommodate the Modernist preoccupation

with free-flowing space. This building was

never actually constructed but if it had been,

the organisation of the horizontal structure of

the roof would have been necessarily more

complex than was necessary with the generic

parallel-wall type of plan. The choices for the

horizontal structure system would have been

either a two-way-spanning system (reinforced

concrete-slab or steel space framework) or one

based on a complex system of primary and

secondary beams.

This project demonstrates that with modern

construction techniques virtually any plan-form

is possible in loadbearing masonry. Non-

regular arrangements of walls produce a

requirement for more complex systems of

horizontal structure than those which are

based on the traditional, and more sensible,

parallel-wall type of plan.

5.2.2 The technical performance of masonry

as a structural material

5.2.2.1 Introduction

The decision by an architect to use masonry

as the structural material for a particular

building is based on a knowledge of its

properties and capabilities in relation to

those of the alternative structural materials.

The proposed form of the building, in relation

to those for which the material is best suited,

will normally have a major bearing on this.

Any design decision has consequences and

one of these is that the constraints and

limitations of the material must thereafter be

accepted. The adoption of masonry will

normally result in the selection of a loadbear-

ing-wall, panel-type structure (see Section

1.3.1). The advantages and disadvantages of

masonry in relation to the other structural

materials are summarised below.

5.2.2.2 Advantages

Strength

Masonry obviously has sufficient strength to

perform as a structural material. It has moder-

ate compressive strength but very low tensile

strength and therefore has a limited capacity

to resist bending. It performs best in situations

in which compression predominates, as in the

walls and piers of buildings of moderate

height. It is also suitable for use in compres-

sive form-active structures such as arches,

domes and vaults.

Durability

Masonry is a durable material both physically

and chemically. Except in the most exposed

situations externally, and often even then, it

can be left free of finishing materials. This both

simplifies the detailing of buildings and

provides a carcass which is virtually mainten-

ance free.

Low cost

Due to the fact that relatively little energy is

consumed in their production and due to their

good availability at most locations, the basic

cost of masonry units and the cost of trans-

porting them to particular sites are low.

Masonry structures can be built using simple,

traditional techniques which do not require

complicated plant or machinery. The construc-

tion process is therefore also relatively cheap;

low cost is one of the principal advantages of

masonry construction.

Appearance

Most masonry has a pleasing appearance

which matures rather than deteriorates with

age. A considerable variety of colours and

surface textures is usually available and may

be used to create a range of architectural

effects.

Design flexibility

The fact that large structures can be assembled

from small basic units allows complicated

geometries to be achieved relatively easily with

masonry and the material therefore offers

considerable scope for imaginative design,

162 subject always to the technical constraints (the