28 An Evaluation On Erzurum Double Minaret Madrasah By

Transcription

KSÜ Mühendislik Bilimleri Dergisi, 13(1), 2010
28
KSU Journal of Engineering Sciences, 13(1), 2010
An Evaluation On Erzurum Double Minaret Madrasah By Structural Engineerıng
Perspective
Dilek OKUYUCU, Abdulkadir Cüneyt AYDIN*
Atatürk Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Erzurum / Türkiye
Geliş Tarihi: 16/06/2010
Kabul Tarihi: 23/07/2010
ABSTRACT: A number of civilizations had occupied on highly strategical and seismic land area of Eastern
Anatolian city of Erzurum. Significantly rich cultural heritage of the city is quite remarkable. City is located on the
highest altitude occupation land of the Anatolian peninsula hosting peak architectural examples of previous nations.
Seljoukian stone edifice of Double Minaret Madrasah is the city symbol for the centuries. This magnificent stone
masonry structure was built on the city center and resembles a number of constructional brilliancies and art beauties.
Evaluation of the whole madrasah by art history or architectural point of view has been stated in many times. These
eight centuries old structural engineering masterpiece suffers from a number of structural problems in the meantime
that requires an engineering point of view to withstand. A visual condition assessment of the madrasah was
performed together with some fictitious ideas related to the construction history of mainly cupola was created by the
authors, since there is no stone legend of the madrasah. Minarets being the most vulnerable pieces of the structure
are of concern first. Attracting engineering attentions towards the architectural heritage protection by this way is
targeted.
Key Words: Erzurum, Seljoukians, Madrasah, Tendon System, Earthquake
Erzurum Çifte Minareli Medrese Üzerine Yapı Mühendisliği Açısından Bir Değerlendirme
ÖZET: Önemli derecede stratejik ve sismik olarak hareketliği yüksek bir coğrafyada kurulmuş olan Doğu Anadolu
şehri Erzurum’ da pek çok medeniyet varlık göstermiştir. Şehrin tarihi kültür mirası dikkat çekici ölçülerde çeşitlilik
göstermektedir. Anadolu yarımadasının en yüksek yerleşim yerine kurulu olan şehir, pek çok medeniyetin önemli
mimari eserlerine ev sahipliği yapmaktadır. Selçuklu taş işçiliği şaheserlerinden birisi sayılan Çifte Minareli
Medrese yüzyıllar boyunca şehrin sembol yapısı olagelmiştir. Şehrin yerleşim merkezinde inşa edilmiş olan bu
görkemli taş yığma yapıda, cesur yapısal detaylarla sanatsal güzelliklerin buluşması gerçekleşmiştir. Yapının
mimarlık ve sanat tarihi açısından ele alındığı çok sayıda çalışma mevcuttur. Yaklaşık sekiz yüzyıl yaşındaki bu
yapı mühendisliği şaheseri, varlığını sürdürebilmesi için mühendislik penceresinden bir bakışla çözülebilmesi
gereken pek çok sorunla karşı karşıyadır. Hiçbir yazılı kaidesi bulunmayan ve bu nedenle yapım tarihi ve süreci
hakkında sağlıklı bilgiler olmayan medresede kapsamlı bir yapısal durum tespiti çalışması yapılmış, kullanılan
malzemelerden hareketle özellikle kümbet bölümünün yapımı kurgusal çıkarımlar yapılmıştır. Medresenin mevcut
durumda en hassas yapısal bileşenleri olan ve yapıya adını veren minareler özel bir ilgi ile ele alınmıştır. Çalışma ile
mimari mirasımızın korunması konusuna mühendislik ilgilerinin çekilmesi amaçlanmıştır.
Anahtar Kelimeler: Erzurum, Selçuklular, Medrese, Tendon Sistem, Deprem
of the area, struggling against its material and stability
INTRODUCTION
Highly seismic and historic land area of Turkey problems. More excitingly, even the cracks on any
hosts numerous civilizations, each of which still historic structure can bravely speak about the ground
provides their fingerprints on Anatolian peninsula by movements and seismic history of its construction area
[1].
different means of cultural entrust.
Cultural and architectural prosperity of
Rich architectural heritage of Anatolia gives
important clues about the historic occupation and munificent Anatolia is naturally too far away to be
identity of the land together with remarkably didactic presented in a short manuscript. There exist numerous
engineering work traces. İshak Paşa Palace of Ağrı, for studies related to historic masonry structures that are
instance, is a unique palace that has the central heating main concern of authors, of Anatolia basically by
system for the first time in the world. Existence of architecture and art history point of views. Civil
marvellous grave stones and spectacular cupola engineering existence even on every piece and part of
(mausoleum) works by locally originated stone the historic masonry should also be emphasized.
(ignimbrite) of Ahlat proves the dates of Turkish Existing historic masonry being the witnesses of time
Seljoukian existence in Anatolia. Yazılıkaya (Written clearly needs the guidance and efforts of civil
Rock), in other words, King Midas Monument in engineering to withstand.
Conservation of the architectural heritage in
Eskişehir is a marvelous open air temple that has
survived over 3500 years, still watching the Phrigia order to carry them to the future is a natural mission for
Valley and waiting for meeting the meantime occupants the responsible authorities, occupants. Protection of
________________________________________________
*For Correspondance: Aydin, A. C., acaydin@atauni.edu.tr
1.
historic structures is a challenging and interdisciplinary
issue. The vulnerable and sometimes very tired historic
structures should be investigated and treated very
carefully and scientific considering the requirements of
the age. Time, climate, seismic activities, manmade
destructions like terror attacks, wars or improper
conservation applications, etc. provide deficiencies on
masonry material and more dangerously, structural
overall strength and stability weaknesses together with
soil and foundation problems.
Structural system upgrading for proper cases is
vital for historic masonry protection, naturally rather
than providing make-up to the surface elements. It is a
difficult engineering performance; to structurally
upgrade an existing historic masonry without disturbing
current state of stress on the elements, giving minimum
disturbance to the masonry body and providing nonvisible applications as possible as it can as a respect to
the master builders of the edifices. Structural problem
diagnose of the historic masonry is the most important
step and necessitates detailed condition assessment of
the building by engineering knowledge and intuitions.
It should be underlined that; any engineering application
should not attempt to carry the historic masonry to its
original state; one can totally destroy it by this way.
Authors wishes to take attentions to a specific
case, Erzurum city and more specifically a Seljoukian
stone work masterpiece; Double Minaret Madrasah by
civil engineering point of view. Erzurum carries the
heavy responsibility of having a huge and remarkable
cultural heritage from different ages. Despite highly
severe climate effects and high seismicity of the land, a
number of stone masonry historic structures, traditional
stone masonry houses still survive by as if challenging
the time and nature effects.
Double Minaret Madrasah is a spectacular
masterpiece of Seljoukian stone work. The Seljoukian
masters of stone have reached their peak, on the
Anatolian peak in Double Minaret Madrasah by, for
instance, creating largest stone vault of their style
without any arch or tie supporting; a confrontation to
the gravity together with an open atrium surrounded by
state of art edifices of revaks, like a kind of stone
jewellery. Magnificent double minarets of the structure
are the greatest symbol of the city.
The very special Seljoukian stone art edifice
suffers from a number of structural and aesthetical
problems that can directly shorten survival life, unless
proper precautions are taken. A detailed surface
evaluation on the madrasah was carried out and special
attention was paid to the most vulnerable pieces of the
complex; minarets and cupola. Some fictitious idea
about the construction has been also produced under the
light of surface investigations.
This study provides information about
occupation history of Erzurum; architecture and
constructional fictitious thoughts about Double Minaret
Madrasah, evaluation of current status of the building
by structural engineering perspective. The vulnerable
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structural condition of the minarets is to be underlined
in detail.
2.
ERZURUM and ITS ARCHITECTURAL
HERTIAGE
Erzurum is located on east Anatolian region of
Turkey. City is not only of great importance for being
the largest occupation by means of population and land
area on the east Anatolia, but also for hosting significant
historical heritage. A number of different nations had
conquered the city after it was founded by Byzantines.
All these nations had left their fingerprints and in some
cases erased the fingerprints of the past cultures.
Although the lack of the information of early
historic times of Erzurum, it is thought that the city was
established by Byzantines in between 415-422 A.C., in
order to provide security against Persian attacks from
East. Up to 1071, this city had been conquered by
Persians, Arabs, and Byzantines for several times. All
these nations had wanted to conquer the city because of
its geo-political location on east Anatolia. In 1071,
Malazgirt had been conquered by Seljoukians as the
gate of Anatolia and a short time later Erzurum city had
also been added to Seljoukian administration. In 1202,
city had been conquered by Mongolians, and they had
killed a lot of occupants together with significant
damages in the city. In 1308, with the destruction of
Anatolian Seljoukian Government the city had been
administrated by Ilhanlı Turk Government up to the
destruction of this government in 1335. Then, a great
mess of administration had been lived in the city by
some small state governments such as relatively small
Akkoyunlu and Karakoyunlu State Governments.
Ottoman Empire archive records addresses that the city
had been added to Ottoman Empire land in between
1518-1519, short after the conquery of Egypt by
Ottoman Conqueror II. Selim in 1517.
During the period of Suleiman the Magnificent,
city had been re-built and prepared for occupancy in
better conditions. Lalapaşa Mosque of the city center is
reported to be a Masterbuilder Sinan’s work, who was
the minister of the settlement of Suleiman the
Magnificent. During Ottoman period, the city had been
very important for security of Anatolia against the
possible attacks of Russians and Persians from east.
Ottoman Empire had located a huge number of soldiers;
janissaries and constructed military buildings,
ammunition and food depots for the military purposes.
Some of these buildings still exist and are used by
Turkish Army meantime.
In 1829, the city had been attacked by Russian
Army and a drastic war had happened for three months.
However, at the end Russian Army had to leave the city
according to a peace agreement. In 1856, a destructive
earthquake had occurred in the city center, resulting in
more than 600 deaths. In these earthquakes, 1462
houses and 867 shops had collapsed; more than 1200
houses had been heavily damaged; 26 mosques, 60
madrasahs and small scaled school buildings, 62
caravansaries and hostels (relatively small caravansary)
had been damaged in varying levels as stated in
Ottoman Empire archives. From 1864 to 1918, a lot of
wars had happened in the city in between Ottoman
Empire and Russian Empire, resulting in destructions
and life losses [2].
Erzurum was called as “Theodosiopolis”
during East Roman Empire period, with respect to the
name of Conqueror II. Theodosios. Also, citizens of the
region called this city with the names of “Karin” or
“Karnoikalak” in ancient times. It was told that, when
the governor of this region was died, his wife Kali had
founded this city and so that Arabs called the city as
“Kalikala”. When Turks conquered (1048-1049) the
neighbouring city called “Erzen”, most occupants of
Erzen had migrated to Theodosiopolis and Turks had
called Theodosiopolis as Erzen for this reason.
However, at that time there had been another city called
Erzen near Siirt city in Anatolia. For this reason, Turks
had called Theodosiopolis as ErzenRum, in order to
separate its name from existing Erzen city. The word of
“Rum” had been added to mean that this city belongs to
Anatolia. On Seljoukian coins which were monetized in
this region, the name of the city had been stated as
Erzenü’r Rûm, Erzen-i Rûm and Erz-i Rûm. Later on,
city had called as Arz-ı Rûm for a long time and this
naming process had finally ended with the current name
of the city as Erzurum.
The architectural heritage of the city center
(towns are not covered), is stated to have existing; 1
castle, 4 gates on the walls surrounding the city, 21
bastions, 2 arsenals, 45 mosques, 5 masjids, 3 stone
tablets showing the praying direction for Muslims, 2
churches, 6 madrasahs, 21 mausoleums (tombs), 8
caravansaries, 14 Turkish bathes, 78 fountains, 3
bridges, 58 traditional Erzurum houses, 1 historic villa.
It is also reported that nearly 229 historical buildings
have some partial remaining or totally collapsed [2].
Most of these destroyed buildings were defined on old
30
pictures, miniatures and gravures of the city. Occupants
had developed their own housing architecture and city
settlement considering the topography (high altitude
from sea level, 1850m for city center) and hard winter
conditions, evaluating the past experiences.
Erzurum is located on a neighboring point at
which north Anatolian and east Anatolian faults met.
City centre is on 2nd degree seismic zone [3].
3.
DOUBLE MINARET MADRASAH
Erzurum hosts a number of historic masonry
structures of different ages, like Seljoukians and
Ottomans. Earlier occupants of the city, Seljoukians
have reached their peak on stone workmanship in
Erzurum with Double Minaret Madrasah. This
magnificient stone edifice is located on the city center,
Tebrizkapı region within the city castle borders
neighboring Erzurum Castle and currently under
management of Turkish Foundations General Directory.
There exist remains of castle walls around the structure.
Madrasah is the common name of the schools
of higher education in Islamic governments in history
and now. After Turks mostly accepted Islam religion in
X. century, Turkish-Islamic Governments had
constructed a lot of madrasahs in their conquering lands.
Karahanlı Turkish Republic is the first Turkish
government that had constructed the first Turkish
madrasah and declared Turkish as the official and
education language of the government. This is also the
first government that had started “student scholarship”
application in madrasah history. It is evident that
Seljoukians had reached the peak of madrasah
construction tradition in the history. Ottoman Empire
then continued constructing madrasahs and transferring
distinguished academicians from other countries to
Ottoman madrasahs for higher quality university
education; providing them better financial, working and
living conditions.
Figure 1. Northern Façade View of Double Minaret Madrasah
31
Due to lack of stone legend on anywhere in the
structure, the exact construction date of the Double
Minaret Madrasah is unknown. Considering the
conquering period of Seljoukians in this region, a lot of
researchers date the structure from lates of 13th century
to earlies of 14th Century (1230 – 1300) [2]. Neither
date is convincing. However, as it is more likely that the
madrasa was completed before the demise of the
Seljoukian state in Erzurum in 1277, and after the Gök
Madrasah in Sivas was built in 1271, the structure
which could be probably taken as a model [4].
Figure 2. First Story Floor Plan Of Madrasah
Structure can be basically evaluated in three
parts as; cupola, stone vault that connects the cupola and
madrasah body and madrasah body with minarets on the
northern façade. It is very difficult to mention a
monolithically construction of madrasah parts since,
masonry materials and visible material deteriorations
create the thought of an older cupola construction with
respect to other madrasah elements.
4.
CUPOLA
Seljoukians have provided a synthesis of
Byzantine and Antique art with Islamic art and Middle
Asia traditions that they have brought to Anatolia with
themselves. Utilization of adoptive antiquity materials
in Anatolian Seljoukian type masonry construction
commonly happened especially in the antiquity centers
Double Minaret Madrasah is the largest
madrasah which also has the biggest open air atrium in
Anatolia [5]. It has a square floor plan in 35x48m. It is
oriented along a north-south axis, with the main portal
facing north. It extends beyond the south iwan (opposite
the portal) to a ten-sided cupola (mausoleum). In this
two story stone masonry structure; there are one open
atrium (26x10m) and four iwans, nineteen rooms on the
first floor and eighteen rooms in the second floor all
entered through the arcade, one cupola with one grave
room under and some small praying rooms. Floor plan
sketches are presented [6].
Figure 3. Second Story Floor Plan of Madrasah
like Konya, Isparta, Antalya, Kayseri, Sivas, Diyabakır,
Urfa, etc [7]. This can be pronounced as a kind of
conservation of existing materials, mainly marble,
which were possibly from the ruins of antiquity
structures. It should be underlined that, adoptive
material utilization from the previous ages was observed
not only in Seljoukians, but also in other civilizations
before. Collection and utilization of old special pieces
from other buildings in the temples dates back to Greek
times. This application was very common in Emevis, for
instance, Damascus Umeyye Mosque; with four
hundred different adoptive parts of Hagia Sophia or a
number of Byzantine constructions that cover materials
and pieces like marble statues, ornamenting or columns
of from past Roman and Greek structures.
Figure 4. Outer View of Cupola
Seljoukian throne gates (taç kapı, in Turkish) in
significantly large sizes are very typical for their
madrasah, caravansary construction. Larger and deeper
sized muqarnases stone vaulting work is surrounded by
rectangular ornamented stone frame in throne gates.
Main gate of the Double Minaret Madrasah on northern
façade is one the masterpiece samples of the Seljoukian
throne gates as well. Throne gates are also provided in
Seljoukian type cupolas, but in relatively small and
fewer impressible dimensions. Non-finalized surface of
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the cupola gate is also very remarkable by this angle.
There exists a rectangular stone framing work attempt
on the gate, as if it was designated to construct on an
existing surface to provide a Seljoukian throne gate. Or,
there had been the throne gate from the beginning, and
it was destroyed during the wars of history. The left
sided wall of the gate from the madrasah body covers
some visible timber elements, maybe resembling the
very first timber confined masonry tradition of the area.
Figure 6. Timber Element Detail on Cupola Wall Figure 7. View of Non-finalized Cupola Gate
Inner dome of the cupola was constructed by
stone and covering second layer of the cone is made of
Seljoukian brick; very characteristic Seljoukian roof
covering system. A geometric band rings the entire
tomb below the cornice. It is supported by a cornice of
muqarnas decoration. Metal clamps on stone floor
coverings of edges exist no longer.
5.
STONE VAULT
International sources cite often cases of Gothic
cathedrals as only referable examples of the vault
components, mostly ignoring meaningful Seljoukian
contribution in development of vaulted structures. The
Seljoukian people were one of the Turkish originated
groups moving from Central Asian areas to the West in
earliest occasions. They are referred as clever people
with a higher level of aptitude for construction work. On
their path of East-West move, they stay for long periods
in Isphahan, Baghdad, Cairo, etc. before reaching the
Eastern Anatolian area. They erected a big number of
vaulted structures during their stops in Isphahan and on
Anatolian land. The great vault taking place in Double
Minaret Madrasah reflects the powerful structural
expression that Seljoukians had brought their edifices.
Cupola of the south is connected to the madrasah body
by a stone vault, indeed series of arches, which is
reported to be the largest and bravest stone vault work
of the Seljoukian stone masters. It is 14.53 m in height
and 15.38 m in length. Vault is supported by 1.55 m
thick masonry walls [8]. It should be stated that,
references from 1913 and 1960 shows that the vault had
been collapsed and a reconstruction work was
performed after.
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Figure 8. View of the Madrasah from Northern Façade to South Side, 1913, by Walter Bachmann, in Public
Domain
Figure 9. View of the Madrasah from Northern Façade to South Side, 1960, by Walter B. Denny, in Aga Khan
Visual Archive, MIT
Figure 10. View of the Madrasah from Northern Façade to South Side, 2010
6.
MADRASAH BUILDING with MINARETS
The structure is a whole monument with its
double minarets on the northern façade as its name
implies: Double Minaret Madrasah. Minaret balconies
were thought to collapse in 1856 Erzurum earthquake.
This can be deducted on the old gravures of structure in
Figure 11. Existing portions of minarets are 11.80m in
height (from kaide level) and 3.10m in outer diameter in
average providing a slight difference in between minaret
diameters, with sixteen semicircles as the continuation
of an architectural tradition with its origins in the
Central Asian Qarakhanid dynasty.
34
Figure 11. Double Minaret Madrasah Gravures
Figure 12. View of Double Minaret Madrasah Minarets
Each minaret sits on an octagonal base set atop
a square pier. These piers frame the entryway and the
monumental portal that projects (in plan) from the north
wall. Each pier is carved in relief at the top and the base,
with a main structure of plain-faced stone. The upper
carving is a calligraphic medallion set in a square, with
inscriptions naming Allah, the Prophet and the four
Caliphs. Although the structure body is mainly made of
stone, the minarets are made of bricks and coated by
grooved blue bricks as ornaments. Inside both minarets,
there exists helical stairs made of stone up to the starting
point of minaret (kaide) and continuing as helical
masonry brick stairs that climbs up to the top. The outer
wall thickness of minarets is 0.60 m in average.
The bases of minarets are decorated in deep
relief with a palm tree which springs from its roots of
intertwined dragons and supports a double-headed
eagle. The entire façade is similar to the Gök Madrasah
in Sivas with carved floral motifs adorning the portal
and a fountain to left of the entrance.
Figure 13. Unique Written Stone Tablet On the East Side of Northern Façade
Figure 14. East Minaret Base Ornaments
Entering through the portal there is a small
domed room to the west that was once a small masjid.
The entrance hall opens through an iwan onto a
courtyard 20x26 m ringed on three sides by two-storey
arcade. The fourth side, to the south, is composed
entirely of a large iwan that leads into the cupola. The
east and west sides each have a central iwans, with
35
Figure 15. West Minaret Base Ornaments
smaller rooms on either side. The doors to these rooms
are carved and decorated in different variations. There
are nineteen rooms on the first floor and eighteen on the
second, all entered through the arcade. Only a few of the
arcade column capitals are ornamented; as if the
madrasah has never been completed.
Figure 16. View of East Sided Revaks and Central Iwan
Madrasah served as university for years, but
also as a gun foundry in the seventeenth century and as
an arsenal and armory in the nineteenth century.
7.
CURRENT SITUATION of the MADRASAH
STRUCTURE
The building is under protection and
supervision of Turkish Foundation General Directory. It
is open for tourist visits and some social activities like
exhibitions.
Approximately eight centuries old
madrasah suffers from a number of problems as
discussed follows [10, 11].
7.1. Humidity Problem
On both inner and outer sides of madrasah
walls, considerable amount of darkening and salt
crystallizations due to high humidity ratios are
detectable. This humidity problem likely originated to
the ceiling is observed both inner and outer places.
36
Structural problems are also concentrated in locations
where high humidity exists. A drainage problem in
structure base soil can also be mentioned. On the outer
sides, the humidity problem is also concentrated on
contact points in between madrasah wall basement level
and the cementitious coatings of sidewalk on the
northern façade.
7.2. Material Problems
Structure is mainly composed of stone and
brick that have been utilized in the minarets masonry.
Significant amount of material and properly section
losses are faced in some locations. These deteriorations
are mainly observed in the locations of high humidity,
moreover on the minaret web. Another serious problem
is observed on the ornaments of structure. Mainly, the
colorful brick ornaments of the minarets were broken
down. Some stone ornaments seem to be very sensitive
of damage as well [10].
Figure 17. Ornamental Material Losses on the West Minaret
7.3. Some Attachments of Later Times
Structure is reported to have been restored for
several times. Due to inadequate cementitious material
usage the salts of cement had created important
deteriorations together with humidity on masonry
material. This problem is basically observed on
restorations of some arches. Reinforced concrete ties for
arches had been placed; room walls and ceilings had
been plastered by gypsum and ordinary mortar. There
are also concrete circular ring element attachments in
minaret inner walls together with epoxy mortar in
between masonry wall materials.
37
Figure 18. RC Ties of Arches
7.4. Structural Problems
The huge volumed and heavy masonry
madrasah body is located on a sloping ground that is the
contact point of two slopes; from southern side to north
and the other from west to east. Clearly observable
cracks and deflections show that the load bearing arcade
columns on both east and west sides of the entrance are
subjected to significant overturning moments. Severe
effects of these moments on the single piece stone
columns provide risk of structural stability collapse
rather than the strength degradation due to wide
diagonal cracks and section losses of the crushing at the
base. These stone columns are no longer leaning from
their axes by remarkably visible, large drifts.
Figure 19. Leaning Stone Column of East Arcade
38
Some of the key stones of the arches on both
each and west sided revaks are very vulnerable to
decompose; not only in the first floor but also in the
second floor. Vertical tensile cracks on the cupola walls
are symmetrical in plan. Decomposition of stones of
three basic lines on the cupola dome widens from the
key stone on the top through three small openings on the
dome body. A number of vertical tensile cracks exist on
the stone cornice, the circular transition zone from dome
to the cupola body, likely as a sign of soil settlement
and movement to south. A steel bracelet had been
placed on the outer side of cornice to possibly prevent
widening due to vertical tensile cracks.
Cupola
basement is also inclined from south to north.
Figure 20. Steel Bracelet On the Outer Side of Cupola
Ten sided cupola has total of six openings other
than the gate. Four of the openings are more likely
shorter height doors and open to outside. Each window
has single piece stone lintel, except the two ones
numbered as 2 and 5 in Figure 21. There exists a lintel
composing of two parts which are connected to each
other by shear key type connection. Separation on
contact line of both shear keyed lintels are quiet visible
as well.
N
2
5
W
E
S
Figure 21. Floor Plan of the Cupola
Figure 22. Number 5 Opening Lintel Detail of Cupola
39
All deflections and cracks provide powerful
signs about a soil movement from south to north, being
parallel to land slope as shown in Figure 23.
Additionally, overturning deformations of the above
mentioned arcade columns likely imply a soil settlement
under throne gate with minarets of the northern façade.
This settlement can possibly occur since the throne gate
and minarets together provide a heavy body.
Soil Movement Direction
Figure 23. Estimated Soil Movement Direction
Structural health monitoring studies on Double
Minaret Madrasah by Turkish Foundations General
Directory continue for a while. Some measurement
gages, mostly gages to measure crack propagation like
clip gages, are placed and the long term deformations
are being measured. The data process of the study
could provide important realistic information about the
authors’ estimated soil movement and settlement. It
should be added that, some gage locations could have
been organized in a more meaningful manner. For
instance, a gage had been settled to measure crack
propagation on a corner stone on the west arcade
column as shown in Figure 24. Blue circled area is the
existing gage location that monitors the crack opening
on the corner stone, while red circled area shows the
decomposition of the stone masonry over the key stone
of the arch even climbing up to the second storey.
Figure 24. Existing Gage Location and Masonry Decomposition on West Arcade
Minarets of the madrasah are currently the
most vulnerable structural members of the structure that
the authors give special attentions. Colorful brick
ornaments of the minaret outer cover had been widely
deteriorated and crushed in most locations. Material loss
problems of the minaret have been very clearly
observed from inside the minaret that was investigated
under hard conditions. There exists some epoxy
injection works and concrete circular element
attachments on the inner face of minaret walls. Cracks
and salt crystallizations are observed on the contact
points of concrete rings and brick masonry wall.
Another potential danger for the minarets
should be stated as the birds. A number of birds, mostly
pigeons, have constructed their nests on the helical
stairs of the minarets. The damage that bird fouling
causes to historic buildings can be extensive [11]. Apart
from the obvious unsightliness, the main problem is
acids released from their excrement. These can cause
irreversible damage to building surfaces resulting in the
scarring of building fabric, damaging appearance and,
potentially, causing large amount of money worth of
damage. Studies have shown that the corrosive effects
can continue for a long time after the stone has been
contaminated, even if the fouling is removed [12]. A
number of anti-perching devices exist as a solution for
this important problem like anti-perching wires, antiperching gels, anti-perching spikes, etc.
Leaning problem of the minarets is mostly
pronounced for the west minaret that neighbors to Ulu
Mosque. Metal bars, likely steel, had been attached in
between the slices of the minaret’s outer wall which are
mostly corroded in color of brown. The date and reason
for this application is officially not stated; moreover
bars are not visible a lot unless zoomed look is
provided. Erzurum city center is located on 2nd degree
40
of seismic zone and city experienced a number of
destructive earthquakes. Existing crack mechanisms on
the minarets provides a more dangerous collapse risk,
when highly seismic activity properties of the land is of
concern.
Authors deal with the stability problems of the
minaret for a while, especially to seismic system
upgrading of the masonry minarets. An initial feasibility
study for application of passive controlled Tendon
Systems for structural upgrading of the minarets had
been performed in corporation with Kassel University –
Germany and Atatürk University – Erzurum. Tendon
Systems are one of the structural control systems for
earthquake protection [13]. In this system, rigid bodies
are connected through single cables or through a cable
network as shown in Figure 25. The pre-stressing
forces of the cables are regulated strategically at given
locations. Therefore, a suitable dynamic mechanism can
be established.
Figure 25. Principle of Tendon System
Suitable
devices
are
spring-dashpot
combinations or shape memory alloy devices. In case of
a strong earthquake, the Tendon System allows
openings in the existing fissures without risk of collapse
and controls at the same time the magnitude of
incoming forces [10, 16, 17].
Initial numerical feasibility study on minarets
had mainly focused on gap element modelling for
historic masonry and finally some tendon arrangements
had been initially proposed [18].
Figure 26. Initial Tendon – Spring System Model with Two Idealized Gap Elements as Crack Locations
Although o design specification or guideline
exist for tendon system application, the method has
been implemented in some historic buildings of Italy,
for instance a historic bell tower in Trignano, Italy. The
18.50 m high tower built in 1302 was heavily damaged
by the 1996 Reggio Emilia Earthquake. The Tendon
41
System consists of 4 tension members running through
the four corners of the tower and anchored at the
foundation. The Shape Memory Alloy devices are
located at the top of the tower passive control devices
[18].
Figure 27. Tendon System Application in St. Giorgio Bell Tower – Trigano/Italy
Current structural evaluation of the minaret has
provided important information about the existing crack
mechanisms that will further direct the study for a
realistic tendon system analysis and design of minarets.
8.
CONCLUDING REMARKS
This study mainly targets to attract the interests
to historic masonry on engineering point of view while
underlining the vital need of engineering treatments of
the architectural heritage to survive. A detailed
condition assessment has been carried out on the Double
Minaret Madrasah within this perspective, producing
the final remarks below.
• Cracks and other deflections are strong clues of a
ground movement from south to north, together with
a soil settlement more locally under the northern
façade.
•
Data process of the ongoing structural health
monitoring study can provide realistic information
about estimated soil movements.
• Archaeological site surveys together with a soil
survey on closer sites to madrasah can provide very
valuable information about the ancient occupations and
engineering soil properties.
• Structural load bearing system of the minarets
should be immediately analyzed and upgraded in order
to withstand.
• Acid providing bird excrement, mostly pigeons,
provide a greater risk to minarets by irreversible damage
to minaret inner and outer surfaces resulting in the
scarring of building fabric, damaging appearance.
• Crack mechanism detections provide an important
data for further tendon system analysis studied to be
proposed as a reliable upgrading solution for minaret
structure.
42
W
E
BACK
E
W
FRONT
Figure 28. Crack Mechanisms On the Minarets
9.
ACKNOWLEDGEMENTS
Authors deeply acknowledge the contributions
of Dr. Erhan KARAESMEN from M.E.T.U. and Prof.
Dr. Uwe DORKA from University of Kassel. Thanks
are also rendered to PhD. Candidate and art historian
Ms. Demet OKUYUCU.
43
Figure 29. A General Sketch that Summarizes Existing Structural Problems of the Madrasah
10. REFERENCES
1. Psycharis, I., N.,2007, A Probe into the Seismic
History of Athens, Greece from the Current State of a
Classical Monument, Earhtquake Spectra, Volume
23, No. 2,: 393–415.
2. Yurttaş, H., Özkan H., Köşklü, Z., Talı, S., Okuyucu,
D., Geyik, G., Kındığılı, M., 2008, Yolların, Suların
ve Sanatın Buluştuğu Şehir Erzurum, Kariyer
Matbaacılık, Ankara, Turkey. (in Turkish).
3. http://www.deprem.gov.tr/
4. Rogers, J., M., 1965, The Çifte Minare Medrese at
Erzurum and the Gök Medrese at Sivas. Anatolian
Studies 15, [63]-85.
5. Aslanapa, O., 1971. Turkish Art and Architecture.
New York: Praeger,:134-35 Ünal, R., H., 1989., Çifte
Minareli Medrese (Erzurum). Ankara: Kültür
Bakanligi.
6. Ünal, R., H., 1989., Çifte Minareli Medrese
(Erzurum). Ankara: Kültür Bakanligi.
7. Öney, G., 1968, Anadolu Selçuklu Mimarisinde
Antik Devir Malzemesi, Anadolu Dergisi, Ankara
Universitesi Yayınları, sayı 12, : 17-26.
8. Anonymous, 2008, Erzurum Double Minaret
Madrasah Architectural Drawings, T.C. Kültür
Bakanlığı Anıtlar ve Müzeler Genel Müdürlüğü
Erzurum Rölöve ve Anıtlar Müdürlüğü. (in Turkish).
9. http://archnet.org/
10. Aydın, A.C., Restoration of Historical Structures:
Material and Structural Point of View, The 1st
International Conference on Sustainable Built
Environment Infrastructures in Developing Countries,
12-14 Oct. 2009, Oran, Algeria, Vol.2, pp.325-336.
11. Anonymous, 2008, Report of Current Status of
Double Minaret Madrasah, T.C. Kültür Bakanlığı
Anıtlar ve Müzeler Genel Müdürlüğü Erzurum
Rölöve ve Anıtlar Müdürlüğü, (in Turkish).
44
12. Channon, D., 2004 Feral Pigeon Excrement On
Heritage Stonework, International Pest Control,
January/February , 46:1
13. Bassi, M., and Chiantante, D., 1976, The role of
pigeon excrement in stone biodeterioration,
International Biodeterioration Bulletin, 12:3.
14. Okuyucu, D., Dorka, U., Sharifi, M., 2009, Tendon
Systems for Seismic Upgrading of Historical
Masonry Buildings - Preliminary Feasibility Study:
Erzurum Double Minaret Madrasah, Symposium
with International Participation on Strengthening and
Preserving Historical Buildings and Cultural Heritage
– II, 15th - 17th October, Diyarbakır, Turkey.
15. Manav., N., 2009, Development of a Tendon-System
Concept for the Assembly Hall of the Double Minaret
Madrasa in Erzurum, Diploma Thesis University of
Kassel. (in German).
16. Dorka, U., E., 2004., Earthquake Protection by
Structural Control, Der Stahlbau. (in German).
17. Sharifi, M., 2009, Tendon-System for Earthquake
Protection of Historic Minarets of Double Minaret
Madrasah in Erzurum, Turkey, Diploma Thesis
University of Kassel. (in German)
18. Castellano, M. G., Indirli, M., Martelli, A., Azedevo,
J. J., Sincarian, G. E., Tirelli, D., Renda, V., Croci,
G., Biritognolo, M., Bonci, A., Viskovic, A., 1999,
Seismic Protection of Cultural Heritage Using Shape
Memory Ally Devices – An EC Funded Project
(ISTECH), International Post-SmiRT Conference
Seminar on Seismic Isolation, Passive Energy
Dissipation and Active Control of Vibration of
Structures, Cheju, Korea.
19. http://www.erzurumlu.net/
20. http://www.usgs.gov/
21. http://www.wikipedia.org/
22. Sinclair, T., A., 1989, Eastern Turkey: an
Architectural and Archaeological Survey, London:
The Pindar Press II, 193-97.

28 An Evaluation On Erzurum Double Minaret Madrasah By

Transcription

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