Structural Ana/ysis of Historica/ Constructions - Modena, Lourenço & Roca (eds) © 2005 Taylor & Francis Group, London, ISBN 04 1536 379 9

Earthquake performance of Suleymaniye Mosque

S.M. Kaya, O. Yuzugullu, M. Erdik & N. Aydinoglu Bogazici University Kandilli Observatory and Earlhquake Research InslitUle

ABSTRACT: In a previous research project on the identification ofthe structural configuration ofSuleymaniye Mosque, earthquake performance, natural frequencies and mo de shapes were determined by both ambient vibra­tion tests and finite element analysis. In the present study the three dimensional finite element model prepared during this research was refined and improved as another step ofthe ongoing research activities for the edifice by adding the small domes to the model and increasing the number of elements to achieve maximum precission in the analysis. Non-destructive material tests were carried out in order to determine the material properties. The etfects of different materiais and different boundary conditions were also combined . A satisfactory correlation is observed between the previous and present analytical results .

INTRODUCTION

Suleymaniye Mosque was built between 1549-1557 by the great Turkish Architect "Mimar Sinan" and named after the legendary Ottoman Emperor Suleyman the Magnificient.

Considered to be the masterpiece of the Ottoman architecture, Suleymaniye Mosque has successfuly sustained several major earthquakes without any severe damage.

It is a fact that research studies carried out up today towards the determination ofthe dynamic char­acteristics of this masterpiece of Ottoman Turkish Engineering is very limited. Within the framework of research activities being carried out at the Earthquake Engineering Department ofKandilli Observatory and Earthquake Research Institute for the historic edifices which was initiated with Hagia Sophia, the present study on historic Suleymaniye Mosque is aimed to explore more on the earthquake performance and dynamic characteristics ofthe monumento

2 STRUCTURAL SYSTEM or SULEYMANIYE

Early Ottoman domed buildings (14th and 15th cen­turies) were based either on the concept of a single dome of medi um size covering the whole inner space or, on the series of small domes one neighbouring the other at the same leveI. In both solutions, thrusts and seismic actions would thus be laterally transmitted to the massive exterior walls or piers.

The structural elements of Suleymaniye are com­posed of domes, transition elements, arches, counter weight towers, piers, walls and butresses and founda­tions. The Suleymaniye Mosque is the main building ofthe Suleymaniye complex. It 's plan dimensions are 61 m in the south direction and 73 m in the perpen­dicular direction. The mosque has an axis of symme­try in the north-south directions. The main dome is 26.2 m in diameter and height reaches 49.5 m from the ground.

The circular base dome is transferred to the square geometry via the four decorated pendantives. The main arches are connected to the main piers at an elevation of 32 m from the ground.

Semi-domes existing in the north and south parts of the structure are connected to the main arches and rest upon the two exterior buttress piers. On either side ofthe semi-domes, an exedra semi-dome enlarge the internai volume of the mosque.There are also five smaller domes both on the west and east of the structure.

The huge dimensions of the main four piers are hidden by means of the detailing provided in the cir­cumference of the piers. These piers are connected to the exterior buttresses via the double arches, at an ele­vation of 10m from the ground. The counter weight towers resting on the top of the main piers provide lateral supports.

The west and east walls, laying under the main arches, rest on top of the small arching frame sys­tems which spring to the main piers and internai columns at an elevation of 10m from the ground leveI.

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3 CONSTRUCTION MATERIALS ANO THEIR MATERIAL PROPERTIES

3. 1.1 Stone and brick The structure is mainly constructed by stone and brick. The major part ofit such as main piers, arches, internai secondary arches, buttress piers, and walls are made of stone. The domes are made of brick and covered by lead.

Among the various types of stones Architect Sinan most widely used is "Kufeki" stone the test results of which is reported in (1). "Kufeki" stone was used as structural material on piers, walls, arches or decora­tive material for covering walls and slabs. The art of using this material can be observed on severa I his­torical edifices built by Sinan. The pore ratio of this stone is rather low. The test results indicate that the mechanical characteristics like compressive, tensile and shear strenghts of the stone increase as a func­tion of decrease in pore pressure, and provide better resistance to externai effects.

3.1.2 Non-destructive tests In order to determine the parameters suitable for the definition of the static behaviour of the edifice, diagnostic investigations are conducted using only simple and rapid non-destructive testing techniques. Tt must be emphasised, however, that the use of only a preliminary evaluation ofthe mechanical character­istics of the masonary by defining their mechanical "quality indices". Even though these tests are unable to supply the quantitative mechanical parameters, their use is very important as they provide information on the homogeneity of the material and on the presence of the structural anomalies.

The only reliable means for the determination of the parameters that influence the mechanical behaviour of the material is that of utilising a slightly destructive method that require some interventions (coring and curing). These actions must be studied in such a way that the disturbance to the member is temporary. At the end ofthe tests, there should be no visible signs ofthe work remain on the structure.

For a historic significant monument Iike Suley­maniye, slightly destructive testing techniques could not be used since even slight alteration in any element is not permitted. Similar non-destructive testing meth­ods were utilised on the exposed surfaces of Hagia Sophia with the above mentioned considerations.

Characteristics which may be specified and are capable of assesment by non-destructive tech­niques are:

• Structural integrity • Durability • Appearance and tolerance.

In Suleymaniye, for the determination of the dynamic moduli and the average compressive strength,

ultrasonic testing method and Schmidt Hammer test­ing method were used.

3.2 Schmidt Hammer lests

Various structural elements were tested in Suley­maniye including main piers, marble columns, infill walls, floors, exterior stone walls. Among them the most reliable measurements are those taken from exposed (uncovered) surfaces like stones of the main piers. Therefore, only the measurements belong to the main piers shall be given in this study.

3.3 Ultrasonic pu/se ve/ocity measuremenl

Four series of ultrasonic tests were conducted on the main piers of the mosque. The selected test locations had exposed surface (without plaster). The test results are summarized in Table 2 below.

3.4 Mortar

Previous structural studies to determine the earthquake worthiness of monumental buildings in lstanbu l like Hagia Sophia (2) have shown that the monllments' static and dinamic behaviour depend strongly on the mechanical and chemical properties ofthe mortar and bricks used in their masonary.

Estimated Elastic Moduli from in-situ ultrasonic tests at variolls brick and mortar locations in Hagia Sophia (2):

Brick: Eb = 3.10 Gpa; Mortar: Em = 0.66 Gpa; Composite: Ebm = 1.83 Gpa.

The modulus of elasticity of the composite mate­rial Ec (brick + mortar) was computed using Ec = 2Eb Em/(Eb + Em) where Eb = Modulus of elasticity

Table I. Compressive strength va lues obtained by Schmidt Hammertest.

Average measured strength

Element (N/mm2)

Main pier I 32 Main pier 2 35 Main pier 3 40 Main pier 4 39

lndicated from Hammer curve Number of (N/mm2) measurements

226 36 310 36 350 36 339 36

Table 2. Average modulus of elasticity.

Test location

Main pier I Main pier 2 Main pier 3 Main pier 4

Modulus of elasticity (N/m2)

2,35 2,77 2,71 2,30

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Table 3. Average modulus of elastieity.

Time (see) Test Length loeation (em) Il

Pier 1 70.0 589.2 Pier I 77.5 632.8 Pier I 93.0 742.2 Pier 1 113.0 838.5 Pier I 120.0 1209.0 Pier I 150.0 2038.4

Pier 2 70.0 556.6 586.6 Pier 2 100.0 765.0 834.6 Pier 2 130.0 984.4 1121.1

Pier 3 70.0 540.4 613.9 Pier 3 100.0 806.0 830.0 Pier 3 130.0 1040.0 1056.0

Pier 4 70.0 509.0 699.0 Pier 4 100.0 1161.0 977.2 Pier 4 130.0 1384.0 1333.0

Table 4. Average modulus of elastieity.

Modulus of Material elastieity Poisson properties (N/m2) . 109 ratio Mass Thiekness

Arehes 3.5 0.20 Piers 10.0 0.18 Domes 3.5 0.18 0.50 Pendantives 3.5 0.20 2.0 Semi-domes 3.5 0.18 0.70

ofthe bricks; Em = Modulus of elasticity ofthe morta r. Therefore, Ec = 50000 kg/cm2 .

4 STRUCTURAL ANALYSIS BY FfN1TE ELEMENT MOOEL

4.1.1 Numerieal modeling The numerical modelling used for Suleymaniye Mosque is created by LUSAS package programo LUSAS (4) is a general purpose finite element anal­ysis system which incorporates facilities for: linear and non-linear; creep, natural frequency, buckling, spectral response, harmonic response, fourier analysis; steady field and transient field analysis and coupled thennomechanical analysis.

The finite element model in this study was obtained through severa I runs. In order to assure the precission ofthe resuJts, the number of elements were kept as high

Modulus of elastieity

Veloeity (m/ see) (N/m2). 109

II II

1188.0 2.54 1224.7 2.70 1253.0 2.83 1347.6 3.27 992.6 1.77 735.9 9.75

1257.6 1193.3 2.85 2.56 1307.2 1198.2 3.08 2.58 1320.6 11 59.6 3. 14 2.42

1295.3 1140.3 3.02 2.34 1240.7 1204.8 2.77 2.61 1250.0 1231.1 2.81 2.73

1375.3 1001.4 3.40 1.81 1112.4 1023.3 2.23 1.88 1119.7 1147.4 2.26 2.37

as possible which increase the run time of the com­puter. However, run time was considerably reduced by the aid of a computer which had a large memory capacity and fast processors.

4.1.2 Struetural mode! properties The total number of elements and nodes in the model were 3989 and 6980 respectively.

In a previous study on Suleymaniye Mosque (3) a three dimensional finite element model was con­structed. During this study, the initial intention was to use SHELL elements for the domes, SOUO elements fort the piers, BEAM elements for the lateral dome buttresse. This selection of elements created problems at the dome leveI such as:

• The beam elements used at side of the dome win­dows increased the actual window opening width.

• The use of beam type element for the lateral dome bracing would increase total stress on the connection node on the arch.

• The problem of where to connect the dome base arose.

Considering the above mentioned problems, and to maintain the homogeneity in the element types; lat­eral dome bracings and the short columns between the dome windows were simulated by 3D SOU O elements which is actually the case in the real structure.

4.1 .3 Struetura! idealization The structural finite element model which was used in the previous study (3) 011 Suleymaniye Mosque was

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Figure I .

x J/

3-Dimensional view of Suleymaniye Mosque.

Figure 2. Modal analysis mode 1-2-3-4.

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improved by utilising the following modifications:

• A detailed study was carried out to determine an optimum number of structural elements. For this purpose the total number of elements were raised to 3989 and the corresponding total number of nodes to 6980.

• Small domes were added to the model which were previouslyexcluded.

Table 5. Results of modal analysis.

Modes

Mode I (Lateral mode in the north-south direction)

Mode 2 (Lateral mo de in the east-west direction)

Mode 3 (Torsional mode) Mode 4 (Diagonal Torsional mode) Mode 5 (Lateral squeezing in east-west and north-south direction)

Frequency (Hz)

3,244

3,420

4,305 4,734 4,745

Table 6. Table of dynamic runs.

• Foundation leveI was lovered 2.5 m below the ground leveI.

• Four different boundary conditions were analysed for different combinations of material properties.

The frequencies corresponding to the first five modes are given in table 5, (Fig. 2)

4.2 Analysis

The results ofthe various dynamic runs under differ­ent combinations ofmaterial properties and boundary conditions are summarized in Table 6.

Four different boundary conditions were analysed for four different combinations ofmaterial properties. Severa I dynamic runs were carried out and finally a model with nearest frequency values to those of ambient vibration tests was selected as the improved model which was used for the spectral response anal­ysis under a scenario earthquake for istanbul. Table 7 gives the material properties used in the analysis.

Table 8 below can be used to compare the results obtained from ambient vibration tests, earthquake

Natural frequencies Model lnpul na me Descriplion FI F2 F3 F4 F5 no

Supl AI Fix in XYZ aI - 5.3 m 3,07 3,23 3,76 4,81 4,93 I 2,84 2,99 3,65 4,17 4,18 2 2,89 3,03 3,03 4,28 4,30 3

Sup2 A2 Fix in XY aI - 2.8 m 3,24 3,41 4,02 5,01 5,12 I 2,96 3,12 3,89 4,32 4,33 2 3,02 3,17 3,91 4,44 4,44 3

B2 Spring in XY aI - 2.8 m A I 3,08 3,29 3,82 4,85 4,91 I 2,85 3,03 3,70 4,20 4,22 2 2,90 3,08 3,72 4,31 4,34 3

Sup3 A3 Fix in XYZ aI - 2.8 m AI 3,52 3,75 4,45 5,35 5,44 I 3,15 3,34 4,26 4,56 4,60 2 3,24 3,41 4,30 4,71 4,73 3

Ambienl tests 3,38 3,44 4,26 4,71 5,85

Sup4 A4 Fix in XYat - 2.8mAl 3,14 3,33 3,89 4,90 5,03 I 2,89 3,06 3,78 4,25 4,26 2

Fix in XY at - 0.3 m 2,94 3, 11 3,80 4,36 4,38 3

B4 Spring in XY at - 2.8 m A I 3, 14 3,33 3.89 4,90 5,03 I 2,89 3,06 3,78 4,25 4,26 2

Spring in XY aI - 3 m 2,94 3, 11 3,80 4,36 4,38 3

A5 Fix in XYZ aI - 2.8 m AI 3,72 3,74 4,47 5,36 5,45 I 3,16 3,35 4,28 4,56 4,6 2

Fix in XY at - 0,3 m 3,37 3,56 4,59 4,88 4,38 3

B5 Fix in XYZ aI - 28 m A I 3,.53 3,74 4,47 5,36 5,45 I 3,16 3,35 4,28 4,56 4,61 2

Fix in XY at - 0.3m 3,24 3,56 4,59 4,88 4,93 3

A6 Fix in XYZ at - 28 m 4,04 4,31 5,34 6,04 6,08 1 3,46 3,68 4,94 4,94 5,06 2 3,58 3,79 5,02 5,14 5,23 3

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Table 7. Material properties used in the analysis.

Modulus of e lasticity values (N/m 2) . 109

Input no Piers (Stone) Dome (Brick) Arches (Brick)

I 10 5 8,5 2 10 3 3 3 3,5 3 3 4 10 3,5 3,5

Table 8. Comparison of model frequencies.

Earthquake Ambient results Previous Improved test results 28/05/ 1994 model model

Mode (cps) (cps) (cps) (cps)

1 3,38 3,38 3,26 3,24 2 3,44 3,42 3,65 3,42 3 4,26 4,3 4,58 4,3 4 4,71 5,21 4,73 5 5,85 5,35 4,74

* Could not be computed.

records and the finite element models . l t is observed that the frequencies of the improved model and fre­quencies observed during 1994 earthquake are very close to each other.

5 CONCLUSrON

The three-dimensional finite element model previ­ously prepared was improved by adding the small domes, lowering the foundat ion levei 2.5 m below the previous levei and increasing the number of elements to achieve maximum precision. These improvements were realised after the preliminary studies on the structural system and the material properties.

In order to determine the material parameters suit­able for the definition of the edifice, diagnostic inves­tigations were conducted using non-destructive testing techniques (Schmidt Hammer tests and ultrasonic pulse velocity measurements). The results obtained

were used in the model and the resulting frequencies were compared with those obtained by ambient vibra­tion tests. By using this comparison, different material properties were applied to the model in order to obtain model ofthe best conformity with the ambient vibration test results.

Four different boundary conditions were analysed for a number of different combinations of material properties.

Several dynamic runs were carried out and finally a model with the nearest frequency values to those of ambient vibration tests was selected.

The improved model showed an acceptable compat­ibility with the test results, the earthquake results of 28.05 .1994 and the results ofthe previous model (3).

Unfortunately , precise documents ofthe works are not found in the archives. The chronicle usually reports the payment of the works, but not their location and technical details which would be very useful for the analysis. lt is essential to obtain as-built drawings and full description of the works for the future studies on the edifice.

REFERENCES

Arioglu , E. & Arioglu, N. 1999. Mimar Sinan'in Ta~iyici olarak Kullandigi Küfeki Ta~inin Mühendislik Gizemi, Mimar Sinan Danemi Yapi Etkinlikler Seminar, istanbul

Durukal, E. & Yüzügüllü, O. 1998 . Non-destructive Test­ing Techniques of Structural Materiais in Historical Structures, /NCOMARECH-RAPHAEL 97/E/412 Com­patib/e Materiais for the Proteclion of ElIropean Cultural Heritage Pact 55, 1998, Athens

Selahiye, A. Determination of Dynamic Properties of Süleymaniye Mosque. M.Sc. Thesis, Bogazici Uni­versity, Kandilli Earthqllake Observatory and Earth­quake Research Im'litute, Department of Earthqllake Engineering

Papayanni, I. 1997. Repair Mortars Suitable for lnterventions ofOttoman Monuments, Studies inAncient Strllcture, Pro­ceedings of the Interna/ional Conference of Ear/hqllake July 14- 18, 1997, /stanbul

Anadol , K. & Arioglu, E. 1973 . Earthquake Resistance of Suleymaniye Mosque, Fiflh World Conference on Earth­quake Engineering, 1973, Rome

LUSAS Finite Element System Theory Manuels, FEA Ltd. , United Kingdom

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