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And
The Walls Didn't Come Tumbling
Down
In
earthquake-prone areas,
traditional building techniques
offer some remarkable solutions. Many will have
seen the heart-rending images of
collapsed reinforced-concrete
apartment buildings that featured
on news bulletins worldwide
following the August 17 earthquake
in Northern Turkey last year. But
few, perhaps, will have noticed
the many brick-and-timber houses
constructed using traditional
methods still standing amid the
ruins. However, the fact that so
many of them did, mocked
conventional wisdom that local
masonry construction was unsafe
compared to modern reinforced
concrete. It also drew attention
to this form of traditional or
vernacular construction, which is
fast disappearing from Turkey’s
urban landscapes. BETTER ADAPTED: It
was with these things in mind –
the loss of the important
expression of the built cultural
heritage that such architecture
represents, together with its
impressive performance in
earthquakes – that UNESCO,
together with ICOMOS, the
Inter-national Council on Sites
and Monuments, and the Turkish
Ministry of Culture organised an
international conference to
investigate such architecture
further. In the words of UNESCO’s
Francis Childe, a co-organiser of
the conference, “the question is
whether, in importing convenient,
reinforced-concrete construction
methods into areas of high seismic
risk, traditional construction
methods, better adapted to such
areas, may not have been
overlooked. And if they have been
overlooked, it is our duty to ask
what could be learned from such
techniques.” Researchers
and architects have rarely
addressed the special seismic
properties of vernacular
architecture, and it is generally
accorded little prestige, being
seen as “primitive” or
unsophisticated when compared to
reinforced-concrete buildings.
Yet, according to Randolph
Langenbach, Senior Analyst at the
Federal Emergency Management
Agency in the United States and a
former Professor of Architecture
at the University of California,
Berkeley, such buildings “form
the cultural context of any
civilization – helping to
provide us with an understanding
of past lives in ways that
individual monuments sometimes
cannot.” They also “can tell
us how people in the past
confronted the problem of creating
structures in which to live and
work under the influence of
adversities (including) the most
extreme threat of all, large
earthquakes.” Food for
thought: It
is tragic, he points out, that in
“modern cities like Istanbul,
which as recently as 50 years ago
was filled with wooden houses,
almost all (the vernacular
buildings) have been knocked down,
often within the space of a single
generation.” It is essential,
Langenbach says, to respect the
work of past generations in order
to understand “the contribution
(it) can make in the future. To
see (following the August 1999
earthquake) these unsung,
unnoticed indigenous
brick-and-timber buildings
standing among the ruins of the
modern world around was enough to
make anyone think.” Traditional
construction techniques found in
earthquake zones, for example,
reveal a process of Dar-winian
style “adaptation”, to
environmental threat.
Timber-and-masonry lacing, a
technique a little like the timber
cross-hatching familiar from
English Eliza-bethan architecture,
is found throughout Turkey and the
Balkans. The taq system of
construction found in Northern
India, uses heavy masonry walls,
bonded together with large,
horizontal timbers. Aspects of the
vernacular architectural tradition
in Nepal, are also adapted to the
risk of earthquakes. TIMBER-FRAMES IN
CHINA: Langenbach argues
that such traditional buildings,
widely distributed across the
world and forming part of many
different architectural
traditions, could provide a wealth
of information to present and
future generations on how
buildings can adapt to seismic
threat and how the problem of
earthquakes may be solved. One
particularly interesting example
comes from China. According to Ms
Zhang Zhiping, Director of the
Conservation Centre for Monuments
and Sites at the National
Institute for Cultural Heritage in
Beijing, traditional timber-framed
buildings have been built in China
for thousands of years. And these
buildings perform excellently in
earthquakes. During the 1996
earthquake in Lijiang, a UNESCO
World Heritage Site, traditional
buildings remained intact while
more modern ones collapsed, even
in the most seriously damaged
areas of the town. Patchwork
Building: One region of the
world in which traditional or
vernacular architecture has
evolved in ways responsive to the
seismic environment is Kashmir in
Northern India. Here, two types of
traditional brick-and-masonry
construction were used until quite
recently, the taq and the
dhajj-dewari, both having marked
anti-seismic properties.
Dhajj-dewari literally means “patch-quilt
wall”, and this aptly conveys
the look of such buildings. Little
mortar is used to bond the
masonry, and it is divided by
timbers into a series of discrete
piers with little or no other
bonding. In the taq system a
similar method is used, except
that both masonry and timbers are
much heavier and the buildings
more massive. During
earthquakes such methods have
marked advantages because they
give ductility to an otherwise
brittle structure, allowing it to
respond to seismic forces without
fracturing or collapsing.
According to Randolph Langenbach,
the way these traditional
brick-and-masonry buildings
respond is significant because the
form of construction used prevents
destructive cracking in one part
of the building and allows energy
to dissipate.” A British visitor
to Kashmir, Arthur Neve, noticed
the superior performance of the
traditional architecture compared
to contemporary colonial-style
buildings when he visited the area
following an earthquake in 1885.
Whereas the latter buildings
collapsed, he wrote, “it was
remarkable how few houses fell...
If well built, the whole house...
sways together, whereas more heavy
rigid buildings split and fall.” David
Tresilian, UNESCO |
Website by © Randolph Langenbach M-Arch (Harvard), Dipl.Conservation (York, England)
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