February 17, 2001
December 27, 2000
TRADITIONAL BUILDING METHODS BEAT
CONCRETE
IN QUAKE ZONES
By Catherine Collins
Randolph Langenbach picked up a
rock and struck the concrete
pillar
of the half-finished house in
Kucuk Armutlu, one of the many
shantytowns that in recent years
have taken root on almost every
empty
hillside in this crowded city.
The pillar, stained by the rusting
grime running through its center,
shattered on impact, and bits and
pieces of concrete mixed with the
rubble below.
"Here you have a high-tech
material, applied in a low-tech
situation. Reinforced concrete is
not a material for Saturday
fixer-uppers," said
Langenbach, a [former] University
of California
architecture professor who was
visiting Turkey to speak at the
first
Earthquake Safe International
Conference, sponsored by UNESCO,
Turkey's Ministry of Public Works,
and the International Council on
Monuments and Sites.
In what might seem to fly in the
face of conventional architectural
and engineering wisdom, the focus
of this conference was apparent in
its small print: "Lessons to
be learned from traditional
buildings."
Specialists from 25 nations
gathered to study not the ruins of
earthquakes, but the buildings
that remained standing, especially
those built using
"vernacular" or
"traditional" methods.
"The message of those
traditional buildings standing
erect among the
ruins of Aug. 17 and Nov. 12
should be read clearly and
correctly
evaluated," said Turkist
architect Ortay Ekinci, discussing
the
devastation of Turkey's most
recent major earthquakes.
Seismically sound construction
techniques are as old as
civilization
itself. But today hundreds of
millions of people living in
densely
populated areas around the globe
are at risk from earthquakes, said
David Michelmore of the
International Council on Monuments
and Sites.
"Social and economic changes
and increasing globalization has
resulted
in the abandonment of traditional
building techniques and their
replacement, in most parts of the
world, by concrete pillar
construction.
"Yet this loss of tradition
can have not only a negative
effect on the
environment but, in earthquake
areas, can lead to human
tragedy,"
Michelmore said.
One after another, the experts
expressed concern that from
Istanbul to
Mexico City, Nepal to Manila,
China to Japan, the inability of
reinforced concrete to withstand a
major earthquake when it is used
incorrectly and with substandard
building practices could lead to
an
unprecedented disaster.
They fear a disaster surpassing
that of the August 1999 7.4
Marmara
earthquake that struck
northwestern Turkey, killing more
than 18,000
people and injuring nearly 50,000.
Reinforced concrete has become the
preferred building material in
most
of the world outside of North
America. It is inexpensive and
fast. In
cities such as Istanbul, older
buildings have been torn down and
replaced by concrete structures.
These structures are in downtown
business districts, line the
highways as midrise apartment
buildings
and have popped up in impoverished
settlement areas, like Kucuk
Armutlu.
If used correctly and under the
best conditions, concrete
structures,
reinforced with steel bars, can
withstand earthquakes. The problem
is
that the methods and raw materials
often are not ideal. And once a
building is up, the quality of the
concrete is nearly impossible to
judge.
Timber construction, similar to
Turkey's himis or timber
with stone
construction, can be found
throughout Europe and Asia. Unlike
inflexible concrete structures,
timber buildings have the ability
to
move with an earthquake and absorb
its force throughout the entire
structure. Many of these
traditional structures stood amid
the rubble
of the last earthquakes.
During the conference, Turkish
architects Demet Gulhan and Inci
Ozyoruk Guney presented the first
hard evidence that people living
in
modern, reinforced concrete
structures died at a much higher
rate than
people living in older,
traditional houses during the
Marmara
earthquake.
In one example from their study,
the Sehitler district of Golcuk
had a
roughly equal number of reinforced
concrete and traditional
structures. Yet of the 290 deaths,
287 occurred in reinforced
concrete
structures and only three occurred
in traditional-style buildings. Of
the 789 traditional buildings, 701
survived the quake undamaged, but
of the 814 reinforced concrete
buildings, only 550 escaped
damage.
Of the buildings that collapsed,
only four were traditional
buildings,
while 60 were made of reinforced
concrete.
"Reinforced concrete frame
structures presented a high level
of damage
due to low-quality concrete,
inadequate engineering, incorrect
construction techniques, poor
detailing, inadequate inspection
or
observation of construction, and
lax attitudes of
authorities in the application of
the building code,"
Gulhan said
during her presentation.
Most of Turkey is considered
vulnerable to earthquakes. Yet
according
to Turgut Cansever, one of the
conference speakers,
"approximately 70
percent of the building stock of
Istanbul was built without
technical
assistance."
Depending on the region, much of
the building stock is illegal,
built
without professional planning or
supervision, like the houses found
in
communities similar to Kucuk
Armutlu.
In the years following World War
II, thousands of people flooded
Turkey's major cities and after
finding a dearth of housing, the
rural
migrants invaded state-owned land
and put up their own houses. Those
illegal buildings became known as gece
kondus, which roughly
translates to "landed
overnight."
Although Langenbach was reluctant
to make predictions about Kucuk
Armutlu's gece kondus in
another earthquake, he said,
"There's an
irony that in this place where
people add to their homes a bit at
a
time when they have the money,
they are better off in smaller,
lower
buildings."
Turkish architect Hayim Beraha,
who was touring the settlement
with
Langenbach, was more direct.
"This will collapse,"
he said. "These
people are from the countryside.
And where they came from, they
used
to know better. The problem is the
perception that living in a modern
house is living in a concrete
house."
"Tradition only survives
where concrete trucks; cannot
reach," Michelmore had
said during the conference.
A few steps down the hillside was
a relic of tradition--a small himis
house with a timber frame, in
which rubble had been stuffed and
held
in place with mud mortar.
The entire exterior surface had
shed its stucco, but that was
evidence
of the building's soundness
because it demonstrated that the
stress
caused by an earthquake was spread
evenly.
A cow thrust his head through the himis
structure's window. "Look, a
cow living in the safest building
in Kucuk Armutlu," said
Langenbach.
"I wish these gece kondu
builders had stopped to study this
building first,
before constructing their
own."
