Civil Engineering Reference
In-Depth Information
structural mechanics. In this sense the essence of an arch is that its component
parts are stressed in compression, whereas the essence of a beam is that it is stressed
in bending (i.e. partly in tension). h us structurally a l at arch is not a beam even
though it is rectilinear in form; and a hollowed beam is not an arch even though
it is curvilinear in aspect.
h ere is also a further ambiguity. In English “vault” is ot en used for subterranean
apartments (e.g. of a tomb, or of a bank) even though neither their geometrical
form nor their statics conform to this term. In other languages the term for the
cathedral church of a city is “Dome” (
Duomo, Dom
) even though the building is
neither domical in aspect nor in construction.
Finally to be noted is the term for the component elements of an arch, vault or
dome. In English these are called voussoirs (taken directly from French). However
some ef ort has been made to distinguish the component element of a dome by
the use of the term
vousson
(again taken directly from French). Whatever may be
the correct or current usage in French, the latter term has never gained signii cant
currency in English.
In view of this multiplicity of reference it seems preferable to begin a survey
with some account of historical occurrence, and on this basis then proceed to an
analysis of form and function of structure.
Arcuated
stone
rooi ng—
dei nition
(β) Early History
If an attempt is made to assess the overall historical development in the use of
stone for arcuated rooi ng, it would seem that this can be largely equated with
progression in the nature of the stone employed, i.e. from random rubble to
roughly dressed stone and bastard ashlar, to i nely dressed ashlar masonry. It is
also advisable to observe a distinction between free standing structures and those
below ground or covered with earth. h is latter distinction has a structural basis.
Arcuated construction exerts a lateral thrust, which is, of course, ef ectively taken
up by the earth surround. (NB the use of vault for a chamber tomb, whatever its
construction or situation.) Finally, as an overall consideration, it is possible to
make the suggestion that the use of stone in arcuated construction derived in some
measure from prior experience in using clay (brick) for this purpose.
h e earliest use of stone for arcuated rooi ng may be found at the beginning of
substantial building construction—in the “Round House” of the Neolithic Middle
East (cf Aurenche,
La Maison Orientale
,
pass
). To the degree that the entire con-
struction embodied rubble (rather than the superstructure was entirely in mud brick
on a rubble substructure) then it was considered that these structures constituted
rubble domes—corbelled it was said, although this term can have little signii cance
when applied to rubble and earth construction (v
Ancient Building in South Syria
280
