- 1.80
50.25
- 1.45
50.60
RETROFITTING
BY SEISMIC ISOLATION
OF CIVIL BUILDINGS
IN ARMENIA
INCLUDING SCHOOL
AND HOSPITAL
Prof. Dr. Mikayel Melkumyan
President of the Armenian Association for Earthquake Engineering
Senior Research Associate / Principal Investigator
Engineering Research Center of the American University of Armenia,
40 Marshal Baghramian st., 375019, Yerevan, Armenia,
mmelkumi@aua.am
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
This fact is attracting the attention of
manufacturing of rubber bearings, are leading to
financial institutions and private investors
significant savings in construction costs.
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 threestorey hospital building with base isolation
started by order of the Hayastan AllArmenian Fund. The application of base
isolation is also envisaged in the future for
private apartment buildings.
Statistics on buildings in Armenia retrofitted
with the application of seismic isolation technologies
Name of building
or structure
Type of seismic
isolation
Dimensions of
buildings
in plan (m)
Number of
storeys
Years of design
Years of
implementation
Place of
implementation
Number and
type of rubber
bearings
Manufacturer of
rubber bearings
Existing
apartment
building with
stone bearing
walls
Existing
apartment RC
frame building
Existing
apartment RC
frame building
Existing school
No 4 with stone
bearing walls
Existing RC frame
building of
ArmenianAmerican
Wellness Center
Base isolation
Additional
Isolated Upper
Floor (AIUF,
roof isolation)
Additional
Isolated Upper
Floor (AIUF,
roof isolation)
Base isolation
Base isolation
52x15
19x19
19x19
38x21
30x20
5
9
9
3
6
1994-1995
1995
1996
2001
2003-2004
1995-1996
1996-1997
1996-1997
2002
2004
Vanadzor
Vanadzor
Vanadzor
Vanadzor
Yerevan
60
(Ø 380, h=200),
HDRB
TARRC, UK;
Min Rubber
Products,
Malaysia,;
Sime Engineering
Rubber Products,
Malaysia
16
(Ø 360, h=220),
HDRB
NAIRIT,
Armenia
16
(Ø 360, h=220),
HDRB
Min Rubber
Products,
Malaysia
41
(Ø 380, h=202),
MDRB
YFRTA,
Armenia
20 (Ø 580, h=300),
9 (Ø 380, h=202),
MDRB
GTMC,
Armenia
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.
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.
202.5m
m
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.
158.5m
m
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.
380mm
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.
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 fivestorey 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.
1
2
8
3
9
4
10
15
16
6
5
11
17
19
12
14 13 12
18
20
7
Stages of installation of seismic isolation in the existing 3-story school building
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50.25
- 1.45
50.60
Existing RC frame building of Armenian-American Wellness Center (AAWC)
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.