Selected Bibliography Architecture - Form Space and Order | Page 311

STR U CTURAL PRO PO RTIO NS

In the construction of architecture, structural elements are called
upon to span spaces and transmit their loads through vertical
supports to the foundation system of a building. The size and
proportion of these elements are directly related to the structural
tasks they perform and can therefore be visual indicators of the size
and scale of the spaces they help enclose.
Beams, for example, transmit their loads horizontally across space
to their vertical supports. If the span or load of a beam were doubled,
its bending stresses would likewise double, possibly causing it to
collapse. But if its depth were doubled, its strength would increase
fourfold. Depth, therefore, is the critical dimension of a beam and its
depth-to-span ratio can be a useful indicator of its structural role.

In a similar manner, columns become thicker as their loads and
unsupported height increase. Together, beams and columns form a
skeletal structural framework that defines modules of space. By their
size and proportion, columns and beams articulate space and give it
scale and a hierarchical structure. This can be seen in the way joists
are supported by beams, which in turn are supported by girders. Each
element increases in depth as its load and span increase in size.

South gateway of the third fence of Naigu, the inner shrine, Ise Shrine,
Mie Prefecture, Japan, A.D. 690

296 / A R C H I TE C TU R E : F O R M , S PA C E , & O R D E R