Selected Bibliography Architecture - Form Space and Order | Page 310

M AT E RI A L P ROP ORT I ON S

All building materials in architecture have distinct
properties of elasticity, hardness, and durability. And
they all have an ultimate strength beyond which they
cannot extend themselves without fracturing, breaking, or
collapsing. Since the stresses in a material resulting from
the force of gravity increase with size, all materials also
have rational dimensions beyond which they cannot go. For
example, a stone slab that is four-inches thick and eightfeet long can be reasonably expected to support itself
as a bridge between two supports. But if its size were to
increase fourfold, to sixteen-inches thick and thirty-twofeet long, it would probably collapse under its own weight.
Even a strong material like steel has lengths beyond which
it cannot span without exceeding its ultimate strength.
All materials also have rational proportions that are
dictated by their inherent strengths and weaknesses.
Masonry units like brick, for example, are strong in
compression and depend on their mass for strength.
Such materials are therefore volumetric in form.
Materials like steel are strong in both compression and
tension and can therefore be formed into linear columns
and beams as well as planar sheet materials.
Wood, being a flexible and fairly elastic material, can be
used as linear posts and beams, planar boards, and as a
volumetric elemen