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Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013, Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2013, Mevcut eski tip kolon-kiriş birleşim bölgelerinin davranışını inceleyen sınırlı sayıda çalışma olması nedeniyle bu tip elemanların davranışları iyi bilinmemektedir. Bu çalışmanın amacı, ülkemizdeki mevcut yapıların durumunu temsil etmek üzere düşük dayanımlı beton ve düz yüzeyli donatıya sahip kolon-kiriş birleşim bölgelerinin deprem etkileri altındaki davranışlarını incelemek ve deprem etkilerine karşı bu davranışlarını iyileştirmektir. Bu amaçla malzeme deneyleri yanında deneysel çalışmalar gerçekleşmiştir. 5 adet tam ölçekli üç boyutlu numuneler üretilmiş ve deneyleri yapılmıştır. Numunelerde düşük dayanımlı beton ve düz yüzeyli donatı kullanılmıştır. Birleşim bölgesinde etriye kullanılmamıştır. Yapılan deneysel çalışmalar sonucunda bu tip elemanların deprem yükleri altındaki davranışı açıklanmış ve uygulanabilir güçlendirme yöntemleri geliştirilmiştir., Inspecting the previous studies it is seem that the behaviour of this type of elements is not well known due to the limited number of studies which examines the behavior of existing old-style beam-column joint zones. The purpose of this thesis to examine the behavior of beam-column joint region that are made of low strength concrete and reinforced with plain bar (that represent our country) under seismic effects and to improve this behavior. Besides, material and experimental tests were also carried out. 5 pieces of full scale three-dimensional reinforced concrete specimens were tested. As a result of the experimental studies the behavior of this type of elements under earthquake loading is described and applicable retrofit methods have been developed., Doktora, PhD

This paper deals with the seismic behavior and a new retrofit strategy of block masonry minaret of a historical mosque in Istanbul. Today, it is a well known fact that earthquakes are one of the most important problems that Turkey and many other countries have to deal with. There are large number of historical mosques and large number of minarets which were built since older times. Since Turkey located in highly seismic zone, the probable damage to the masonry minarets should be determined in advance and necessary precautions should be taken. The problem of seismic protection of the historical heritages have been always challenging for engineers in terms of analyzing and retrofitting of these structures due to extremely complex behavior of the material used in the construction. To achieve this objective, the minaret of historical mosque in Istanbul is chosen as a case and 3D finite element model of structure have been prepared to obtain plausible lateral displacements, probable cracking zones and failure modes under earthquake loads. The problem becomes more complex when the dynamic analyses are also involved. After the developments in the dynamic testing of structures and computational methods in structural analysis, studies in this field have led some significant results about the mechanical behavior of the old buildings. These types of studies are essential not only in protection/retrofit viewpoint but also assessment of similar historical structures. Within this outline, the dynamic behavior of old masonry minarets, which usually exhibit vulnerable behavior under seismic loading, was investigated. The results obtained from the numerical analysis have shown that the possible failure zones under seismic action can be predicted quite accurately with reasonable results, and can be used in the preservation of these minarets to guarantee their stability in case of an earthquake by reinforcing those parts which will undergo the greatest damage (usually located at the base and the lower part of the minaret). Furthermore, the analyses are performed by using fiber reinforced polymer (FRP) sheets wrapped around these critical cross sections and the results are promising in terms of seismic protection of these heritages. Preservation of cultural heritage for the future generations is indispensable for every country in the modern world. Therefore, paying enough attention to protection of historical structures is one of the most important issues in highly-seismic developing countries.

Two of major problems for seismic rehabilitation of existing buildings are the necessity of evacuation of the occupants from the basis of the construction works and the limited time frame available for the actual construction site works. All of these problems often cause delays and cost overruns in the seismic rehabilitation projects. One possible way to eliminate these problems to a great extent is the use of FRP (fiber reinforced polymer) and steel fuse elements to improve seismic capacity. There is a huge stock of seismically deficient buildings that needs to be upgraded immediately according to the current Turkish Seismic Code (TSC 2007). The main aim of the paper is the examination of the possibility of using FRP and steel fuse elements on existing frame elements for seismic upgrading of the school and hospital buildings in Turkey. To investigate the possibility and effectiveness of the use of the hybrid system, a comparative study was performed. The comparison has made between typical framed RC building and the same building after retrofitting with FRP confinement and steel fuse elements around joints. By using nonlinear static (pushover) analysis, the performance levels of structural members were evaluated for both structures. This method seems as viable solution for the buildings considered in terms of safety and time.

Creating openings in the webs of steel I-section beams has been a common method of incorporating services within the floor–ceiling zone of buildings. In the literature, the web opening problem was dealt with only for steel beams with plane web plates and the effect of an opening on a corrugated web was not considered. The present paper deals mainly with the effect of web openings on the shear strength/stability of sinusoidally corrugated web beams. A general purpose finite element program (ABAQUS) was used. Simply supported corrugated web beams of 2m length and with rectangular web openings at quarter span points were considered. These points are generally considered to be the optimum locations of web openings for steel beams. Various cases were analyzed including the dimensions of the openings and the corrugation parameters such as the amplitude of the sine wave and corrugation density. Models without web holes were also analyzed and compared with other cases which were all together examined in terms of load-deformation characteristics and ultimate shear resistance.