Mevcut bir betonarme kamu binasının performans analizi ve sismik izolasyon ile güçlendirilmesi
Performance analyses of an existing reinforced concrete public building and retrofitting by base isolation
Yazar: CEREN CİCEN
Danışman: PROF. DR. MEHMET HASAN BODUROĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Deprem Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2014
Konu: Deprem Mühendisliği = Earthquake Engineering

Özet:
Ülkemiz, jeolojik konumu açısından incelendiğinde sismik aktivitesi yoğun bir bölgede olduğu net bir şekilde görülür. Türkiye, Alp-Himalaya orojenik kuşağı içerisinde yer almaktadır. Kuzeyden Avrupa-Asya levhaları, güneyden Afrika-Arabistan levhaları tarafından sıkıştırılması nedeniyle makaslama kırılması oluşmuştur ve bu kırılma şekli, kuzeyde Karadeniz levhacığı, Kuzeydoğuda Hazar levhacığı, güneydoğuda Van levhacığı ve batıda Ege-Anadolu levhacığını meydana getirmiştir. Bu sistem kuzeyde doğrultu atımlı sağ yönlü bir fay olan Kuzey Anadolu Fay Hattı ve yine doğrultu atımlı sol yönlü fay olan Doğu Anadolu Fay Hattı ile kontrol edilir. Bu iki fay sistemi üzerinde büyük magnitüdlü depremler meydana gelmekte, malesef sağlıksız yapılardan dolayı birçok can ve mal kaybına neden olmaktadır. 
Deprem ülkesi olarak tanımlanan ülkemizde, yapıların herhangi bir sismik etkiye maruz kaldığında bu etkiyi karşılayıp karşılamadığı sorusu oldukça önem kazanmıştır. Özellikle mevcut yapıların sismik performansı, deprem mühendisliği alanında büyük önem teşkil etmektedir. Bu çalışmada, seçilen mevcut bir betonarme bina ile, binaların performans değerlendirmesi ve sismik izolasyon tekniği ile güçlendirilmesi üzerine çalışılmıştır.
Birinci bölümde öncelikle, DBYBHY 2007- Bölüm  2'de belirtilen düzensiz binalar tanımlanmıştır. Yapısal ve düşey doğrultuda düzensizlikler, türlerine gore ayrı ayrı ele alınarak şekiller yardımıyla açıklanmıştır. Yine DBYBHY 2007' de Bölüm 7' ye gore, seçilen bir performans seviyesi için, yapıların performans değerlendirmesi üzerinde durulmuştur. Değerlendirme aşamasında kullanılan analiz yöntemlerinden eşdeğer deprem yükü analizi ayrıca açıklanmıştır.
İkinci bölümde, çok serbestlik dereceli sistem  olarak tanımlanan yapıların, eşdeğer tek serbestlik dereceli sisteme çevrilmesi için kullanılan DDBD yöntemi tanımlanmıştır. Anahtar parametresi deplasman olan bu yöntemin, çoğunlukla kullanılan kuvvet tabanlı yöntemlerden farkları ve avantajları ayrıca ele alınmıştır. Elde edilen eşdeğer tek serbestlik dereceli sistemi karakterize eden parametreler belirtilmiştir.
Üçüncü bölümde deprem yalıtımının çalışma prensibi üzerinde durulmuştur. Yalıtım ara yüzüne yerleştirilerek yapıyı sismik dalgaların direct etkisini diskalifiye eden isolator türleri hakkında bilgi verilerek, histerezis eğrileri şekillerle belirtilmiştir.
Dördüncü bölümde, mevcut bir betonarme yapı üzerinde yapılan performans değerlendirmesi ve sismik izolasyon ile güçlendirilmesi örnek bir çalışma olarak ele alınmıştır.

Abstract:
It's quite clear that our country is located in intensively active seismically when it was investigated as its geological location. Turkey is on the alpine-himalayan orogenic belt. It's forced by the Europian-Asian plate on the north and forced by the African-Arabian plate on the south. Since, shear rapture has occurred and as a result of this rapture, Blacksea plate on the north, Hazar plate on the north-east, Van plate on the south-east and Aegean-Anatolian plate on the west has formed. 
 This system is controlled by the North-Anatolian Fault System on the north and East-Anatolian Fault System on the east. On this two fault system, earthquakes with large magnitudes occurs and unfortunately, it cause a lot of less because of poor buildings.  
It's an important question in our country where defined as an earthquake region that the construction is able or not to supply the seismic effect. Especially performance of buildings where located in old building area have importance for earthquake engineering. Because of this, performance analyses studies increased on existing constructions. 
After owner and engineer decide for performance level, it's expected that the building reached to defined performance level because of seismic effect. The retrofitting is unavoidable if it didn't supply. Base isolation is a new retrofitting technic which prefered by earthquake engineering recently.
In this study, performance analyses according to 2007-Turkish Code  and retrofitting by base isolation of buildings were worked on a existing reinforcement building. Isolator design is performed according to UBC-97 and performance calculations has done according to Turkish Isolation Code.
In the first chapter, principally irregular buildings were defined which specified in DBYBHY 2007-Chapter 2. Structural and vertical irregularities were defined sort of their part. Again according to DBYBHY 2007 Chapter 7, for a choosen performance level, peformance analyses for buildings were explained. Equivalent Seismic Force method which one of analyses method used for evaluating was also defined. 
In the second chapter, Direct Displacement Based Design method used for convertion of structures defined as multi-degree freedom system to equivalent single-degree of freedom system were explained. Also, advantages and differenties of this method which has the key parameter as displacement from the other generally used by engineers force based seismic design methods. 
The essential of this method is obtaining an equivalent single-degree of freedom system which symbolize the multi-degree of freedom system. Effective mass, equivalent damping, effective height and effective stiffness are the parameters of the single-degree of freedom system. For this building in this study, the parameters obtained which characterized the equivalent single- degree of freedom system  were noticed.
In the third chapter, the working principle of seismic isolation were discussed.  Seismic isolation is a design based on the absorbing the seismic waves which affected to the building. The isolation system is located at the foundation or first floor level. By this system, forces accelerations and relative floor displacements  will be reduced. The fundamental period of the super-structure will be rised.
 It's quitely important that the isolator type should be satisfy the expected behaviour. Rubber isolator, rubber with lead core isolator are the major types of isolators. Each isolator types has a different hysteresis curves. During the  design process, expected isolator behave is determined by the engineer. The isolator which will provide the expected effects are designed by the producer. 
In this study, Hysteresis curves of isolators are explained by figures. Choosen isolator has designed according to UBC-97 and located at the foundation. It's seemed that the isolation system provides the sesimic effects. 
    In the forth part, an example study on existing reinforcement building were discussed for performance analyses and retrofitting by base isolation. Model of building was formed by using SAP2000 program.
 By the Equivalent Seismic Force method, earthquake forces are determined and acted to each floor level. Floors are defined as rigid diaphram. Under the seismic effects, building behavior was observed and period of the building has determined. Also, floor  displacements were taken as output from the program and maximum and minimum floor displacements are determined. 
At the next step, vertical and structural irregularities analysed according to 2007- Turkish Seismic Code. A1 buckling irregularities and B1 strength irregularities are determined for the building. There is no vertical irregularities at the structural members.
  For performance analyse of the building "Life Safety" performance level was choosen. For defining of member section, cracked section was used and stiffness of members are reduced. P-M diagrams which shows the capacity of columns were obtained. For this diagrams, SPcolumn software program was used. By taking forces which effect to columns from the program, compared with the P-M diagrams. 
As a result of this compare, shear check and demand/capacity ratios of columns were calculated. It's seemed that columns are mostly shear and whole of them are in collapse region. This result support that the building should retrofit. 
At the next step, by the DDBD method, effective stiffness, effective height and mass, equivalent damping parameters of equivalent single-degree of freedom was obtained and calculations were formed for each isolator whick will located under the columns at the base.
For calculating of effective stiffness of each isolator, the effective stiffness of the single-degree of freedom system was seperated at the rate of axial force which effected to column that isolator located under. The mechanical and geometrical properties of isolators were designed according to Turkish Isolation Code.

At the end of the study, designed isolator parameters input the program and building behavior was observed. It' observed that, because of the isolation system, the building behave as a rigid mass and relative floor displacements reduced.
Obtained data by the analyze of building, brought into question in the results chapter.