Civil Engineering Reference
In-Depth Information
i.e. massive columns supported beams and the rooi ng slabs spanned from beam
to beam. Very ot en these rooi ng beams were composite, i.e. of two beams side
by side, and even two beams one above the other giving a total of 4 elements).
It was a general rule that such slab rooi ng was also paved with substantial stone
blocks, so that the combined burden of slabs and paving was very great (always
of the order of several tons per square metre). h is involved two consequences.
h e upstanding supports (walls and columns) were of massive construction; and
(because of the weakness of stone in tension) the rooi ng slabs and beams were
stressed ot en beyond safe limits and failed in tension. h us relatively few rooi ng
slabs have survived in position intact to the present day.
In turn the upshot of this is that Egyptian style slab rooi ng for monumental
building was never a feasible proposition in other parts of the ancient world. Its
structural heritage is to be found outside the Ancient World as here dei ned,
viz
in Hindu monumental stone building—particularly in the Dravidian style of
Southern India.
Arcuated
stone
rooi ng
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256
(b)
Arcuated Rooi ng
(α) Terminology
Any attempt to outline briel y the use of stone to construct arcuated rooi ng
confronts an inital obstacle in the very ambiguous use in English of the relevent
terminology. h is can refer indif erently to: geometrical form; statical functioning;
and type of building. h us the one term can be applied in three senses, so that
where it correctly indicates the nature of an item in one sense, it is erroneously
applied in another.
First a substantiation of “arcuated”. h is is a convenient generic term to com-
prehend arch, vault and dome. Strictly speaking the arch is hardly to be considered
as rooi ng since the dimension other than the span is restricted and thus it can-
not cover a signii ant area. However since the arch is the generating form of the
vault and the dome, the three forms are properly considered ensemble. A vault is
the linear extension of an arch; while a dome is generated by the revolution of an
arch about its vertical axis. Here it is to be emphasized that the concern is with
geometrical form not with construction or functioning.
When spoken of in this fashion the geometrical form of the arch (and hence of
its derivatives) is always understood as curvilinear. However when considered in
connection with building construction, a curvilinear proi le is not a
sine qua non
,
nor indeed is it the essence of the matter. An arch can be constructed so that it
is l at (horizontal) or triangular. On the other hand a beam can be shaped so that
it is of curvilinear proi le. What is in issue here is thus not geometrical form but
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