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 Prof. Dr. Mikayel
MelkumyanPresident of the Armenian Association
for Earthquake EngineeringSenior Research
Associate / Principal Investigator Engineering
Research Center of the American University of
Armenia, 40 Marshal Baghramian st., 375019,
Yerevan, Armenia, mmelkumi_at_aua.am
RETROFITTING BY SEISMIC ISOLATION OF CIVIL
BUILDINGS IN ARMENIA INCLUDING SCHOOL AND
HOSPITAL
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Since 1994 a total of 26 buildings and
structures have been designed in Armenia that
incorporate seismic isolation bearings. The
number of base- and roof-isolated buildings
already constructed in Armenia has reached 14.
Currently, several base-isolated apartment
buildings are under construction in Armenia.
Seismic isolation in Armenia is developing
mainly through projects financed by foreign
institutions (World Bank, Swiss CARITAS),
individual investors (Mr. John Huntsman) and
persons, constructing their own houses.
The point is that seismic isolation techniques
developed in Armenia, taking into account local
manufacturing of rubber bearings, are leading to
significant savings in construction costs.
This fact is attracting the attention of
financial institutions and private investors from
abroad. Nevertheless, the advantages of
seismic isolation are so obvious that in the last
two years local projects have started to show
some interest in the application of seismic
isolation. Recently the construction of a
three-storey hospital building with base
isolation started by order of the Hayastan
All-Armenian Fund. The application of base
isolation is also envisaged in the future for
private apartment buildings.
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Statistics on buildings in Armenia retrofitted
with the application of seismic isolation
technologies
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The structural concept developed in 1994 (M.G.
Melkumyan, Patent of the Republic of Armenia No
579) aims to retrofit an existing building by
means of seismic isolation, using simple working
technology. This is a unique, pioneering seismic
isolation project introduced in 1995-1996 for an
existing five-storey stone building. The project
was financed by the World bank.
The idea is to supply this building with
seismic isolation by gradually cutting it from
its foundation and installing the isolators at
the level of upper edge of the foundation between
a two-stage system of RC beams. The operation is
made without resettlement of the occupants. World
practice provides no similar precedent in
retrofitting of apartment buildings. In
addition, this technique was shown to be much
cheaper than conventional strengthening methods.
Conventional strengthening involves fitting a
reinforcing steel mesh to the bearing walls and
spraying on concrete. For rehabilitated building
the cost would have been about US 340,000. The
cost of seismic isolation is only about US
200,000, a substantial saving.
The HDRB for seismic isolation were
designed in collaboration with TARRC (UK). As the
range of the static vertical loads on each
bearing is quite high, it was decided to have two
types of bearings Soft -S and Hard -H,
differing only in the shear modulus of the
rubber. The design horizontal displacement was
130 mm. The bearings were to operate safely up to
1.5 times the design displacement.
The bearings were tested at TARRC, using
a single bearing facility. Under the design
vertical load and the maximum horizontal
displacement of 195 mm there was no sign of an
approach to the displacement capacity of the
isolators.
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The project on upgrading seismic
resistance of nine-storey RC frame buildings by
means of additional isolated upper floor (AIUF)
pioneered the applications of seismic isolation
structures to the top part of the buildings and
was implemented in 1995-1997. The project was
financed by the World Bank. There are 16 columns
in the plan of the buildings.
All columns pass through the slab of the ninth
floor into the space of the attic floor and are
taken into steel jackets. The assembling of AIUF
over the building starts after dismantling the
attic floor. The connection of AIUF to the
building was designed by means of HDRB.
The steel jackets of all 16 columns were
connected to each other by means of steel
trusses. Thus, a rigid structure is created to
transfer the forces from AIUF to the building.
Under the earthquake impact AIUF, acting as
vibration damper, reduces the stress-deformed
state of the building and increases earthquake
resistance, on average by a factor of 1.6.
It is worth noting that the isolated upper floor
allows not only upgrading the earthquake
resistance of a building, but enlarging its
useful space as well. The most distinctive
feature of the new earthquake resistance
upgrading method, however, is that there is no
need to re-settle the occupants of the building
during construction.
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For this project of retrofitting of 50
years old school No 4 building in Vanadzor 41
seismic isolation MDRB were manufactured from
neoprene by YFRTA and were tested locally. Their
parameters were the same as described above for
the five-storey building, but the design
displacement was taken as 190 mm with 8 damping.
In this case again the innovative technology
proposed by Prof. Dr. Melkumyan (Patent of the
Republic of Armenia No 579) was used. The project
was financed by Swiss CARITAS.
All existing buildings in Vanadzor, including
five-storey stone apartment building, nine-storey
RC frame apartment buildings and three-storey
stone school building, were retrofitted by KANAKA
OJSC, one of the best construction companies in
Armenia.
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Stages of installation of seismic isolation in
the existing 3-story school building
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Existing RC frame building of Armenian-American
Wellness Center (AAWC)
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Conclusions

• The present transition period of the economic
  development in Armenia brings to conclusion that
  non-conventional approaches, allowing the
  retrofitting of existing buildings without
  interruption of their functioning are more
  preferable.

• Within a very short period of time since 1993,
  new unique and effective non-conventional seismic
  protection methods were developed and introduced
  into the construction practice. The description
  of the structural concepts of these methods,
  which can provide the significant seismic safety
  for the existing vulnerable buildings, is given.

• The proposed non-conventional methods are based
  on the application of different types of seismic
  isolators. Fife projects were developed and
  implemented in Armenia in the cities of Vanadzor
  and Yerevan to upgrade the earthquake resistance
  of the 9-story apartment buildings by means of an
  AIUF (roof, isolation) and to retrofit the
  5-story apartment building, 3-story school
  building and 6-story clinic building by means of
  seismic isolation. In all described cases people
  do not need to move from the buildings for the
  whole period of construction works on
  implementation of seismic isolation technologies.