Civil Engineering Reference
In-Depth Information
into a round one to be domed. Centering required for this purpose inevitably must
have been standing centering.
In fact it is possible by various devices to build brick domes without centering,
but this was not the procedure at Ayia Sophia which was constructed with the
use of centering. h us the same questions of building procedure and installations
arose as with the Pantheon 400 years earlier. Was the centering l ying centering
or standing centering? Was the work of constructing the centering carried out by
way of a forest of heavy timbers rising from the pavement, or could this be avoided
and centering installed supported in some way other than from the ground? Main-
stone in his comprehensive treatise on Ayia Sophia (Hagia Sophia London 1988)
while discussing exhaustively the fabric and the statics of its arcuated construction
(cf e.g., pp. 112, 164-5, 172, 204, 207,
et pass
) avoids pronouncing on the nature
of the centering used in this arcuated construction. He notes that it is theoretically
possible to construct brick domes with l ying centering or with standing centering—
or with no centering at all (cf pp. 262, 273).
He also notes that there is evidence that both l ying centering and standing
centering were known and used in earlier Roman construction, including that
of large scale concrete domes (cf p. 273). Further he notes that Roman builders
had, on occasion, built domes of brick as well as concrete (cf the Temple of Diana
at Baiae v Adam, p. 205, i g 450). h us whatever type of centering may or may
not have been used for the construction of the brick dome (and semi-domes) at
Ayia Sophia, precedents existed in Roman building of several centuries earlier.
In short although Mainstone avoids the subject of the nature of the centering
employed at Ayia Sophia, ef ectively he states that the installation and procedure
of domed construction at Ayia Sophia in 532 AD-537 AD were those employed
by Roman builders during the i rst and second centuries AD—i.e. there had been
no innovation in the procedure of constructing large span domes in the interim.
h e building material at Ayia Sophia was dif erent but the building procedure the
same as at the Pantheon.
In this fashion the question of the nature of the centering employed at Ayia Sophia
stands as it stood for the construction of the Pantheon dome. Failing any detailed
study and expert opinion on the subject, a common sense appraisal is that in spite
of the enormous trouble and labour involved, a forest of standing scaf olding was
the most convenient installation providing for all the requirements of constructing
the Ayia Sophia dome, including its centering (cf Vol. I, p. 142) and also for the
subsequent decorative plastering of its soi te when the structure was completed.
To the above statement that there had been no innovations in the procedure for
building domes since the construction of the Pantheon, a rider must be added—a
very strange one, indeed. Only a decade before Ayia Sophia was built (ca 520
AD-530 AD), a monumental tomb had been built at Ravenna for h eodoric the
Ayia
Sophia
Brick
masonry
dome
378
400
