Master Degree / Yüksek Lisans Tezleri

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Language: search.filters.language.enSubject: search.filters.subject.Structural analysis (Engineering)

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Now showing 1 - 6 of 6
  • Master Thesis
    Investigation of Coupling Methods for Floating Offshore Wind Turbines and Their Application for an Innovative Floating Platform
    (01. Izmir Institute of Technology, 2024) Değirmenci, Olcay; Özkol, Ünver; Özkol, Ünver; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Fosil yakıtların yerini alacak daha çevreci enerji kaynaklarına olan ilgi arttıkça, çeşitli enerji alanları da devreye girmektedir. Bunlardan biri ve giderek artan potansiyeli ile dikkat çeken deniz üstü yüzer rüzgâr enerjisi, önemli araştırma konularından biri olarak platformun OpenFAST gibi aero-hidro-servo-elastik programlara entegrasyonu veya benzer aero-hidro kuvvetlerinin bir arada verilmesi yöntemlerinin incelenmesini kapsamaktadır. Bu tez kapsamında daha önceden 300 kW ve 5 MW değerleri için tasarlanmış olan yenilikçi yüzer platformun 5 MW'lık NREL referans rüzgâr türbini için ölçüleri ve özellikleri analizlerde kullanıma uygun şekilde düzenlenmiştir. Literatürde yaygın olarak kullanılan spar, semi-submersible platformlara ek olarak yenilikçi platform için akuple yöntemleri incelenmiştir. Türbinlerin ve platformların sistem tepkilerini ve davranışlarını görmek için doğal periyotları ve sönüm oranlarını bulma, serbest salınım testleri, düzenli, düzensiz dalga koşullarında, sabit ve türbülanslı rüzgâr koşulları dahil çeşitli koşullarda analizler yapılmıştır. Bunun sonucunda, akuple yöntemlerinin doğrulanması, platformların birbirleriyle karşılaştırılması, yenilikçi platformun esnek ve rijit yapısındaki farklı davranışlar incelenmiştir. Bu bağlamda, OpenFAST'a girdi olarak hidrodinamik katsayı sağlayan açık kaynaklı Capytaine ve NEMOH gibi programların yanı sıra AQWA gibi ticari programların, WAMIT gibi yaygın olarak kullanılan ticari programın OpenFAST çıktılarıyla benzer sonuçlar verdiği görülmüştür. Ayrıca, F2A akuple yönteminin de bu sonuçlarla oldukça tutarlı olduğu gözlemlenmiştir. Ayrıca, platformlar karşılaştırıldığında, bağlama halatlarındaki kuvvetlerin özgün platformda diğer platformlara göre daha yüksek olmasına rağmen, özellikle sistemin kararlılığı açısından önemli bir kriter olan platformun yunuslama açısının önemli ölçüde daha düşük olması sebebiyle, kule, kanat ve sapma yatağı gibi bileşenler üzerinde diğer platformlara kıyasla daha az yük oluştuğu hesaplanmıştır.
  • Master Thesis
    Response of Vertically Loaded Energy Piles Under Earthquake Excitation
    (2023) İşbuğa, Volkan; İşbuğa, Volkan; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Pile foundations are deep foundation systems that are used to transfer loads from superstructure to soil by either resisting surface friction or reaching a deeper and stiffer soil layer when geotechnical properties of the soil site are not sufficient to carry the loads transferred from superstructure. Energy piles fulfill the same function along with the ground heat exchanging via heat pump systems, thus satisfying the energy demand of a building for heating-cooling operations. This feature of energy piles draws attention as an innovative system supplying a renewable energy resource. However, heat exchanging operations of energy piles cause temperature variations on pile and the surrounding soil which may cause additional load and deformations. Moreover, temperature variations may affect the elasticity modulus of soils and shear strength of cohesive soils. In this study, earthquake response of an axially energy loaded pile was investigated considering the heating effect under 2020 Izmir earthquake motion using finite element method and compared to the those of identical regular piles. We performed analyses with different soil types, geometric properties, and temperature magnitudes under steady-state heating. Based on the analysis results, heating effect on pile head stiffness with respect to geometric properties were obtained. Two important conclusions have been made; (i) the most critical effect on heating depends on mechanical loading condition of pile and thermal expansion coefficient of soil, (ii) geometric properties may affect the temperature distribution resulting in an unforeseen change in pile head stiffness.
  • Master Thesis
    Effect of Column-Beam Moment Capacity Ratios on the Frame Plastic Failure Mechanism
    (01. Izmir Institute of Technology, 2023) Akhtari, Rohullah; Dönmez, Cemalettin; Dönmez, Cemalettin; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The strong-column weak-beam design ratio plays a crucial rule to design the structures particularly for high seismic region. Interestingly, the ratio to be used is still under spotlight for research. Observations and analytical studies have demonstrated that the ratio's effectiveness varies with some parameters. One of these parameters is the number of stories in a building. The failure mechanism of the structures depends on this ratio and the design ratio efficiency seems to change as building's stories increases. This efficiency also seem to saturate at a point depending on number of stories. In this study, three case studies have been assessed and analyzed. Each case study contains three reinforced concrete frames with different strong-column weak-beam design ratios that varies from 1.2 to 3.0. For each case study, the design ratios are ranged into three parts: (i) ratios between 1.2 to 1.5; (ii) ratios between 1.5 to 2.0; (iii) ratios between 2.0 to 3.0. The Turkish Earthquake Regulation (2018) has been utilized for the design procedures. The pushover and time-history analysis of frames were performed using OpenSees software framework (McKenna et al., 2010). Columns have been modeled with fiber sections and the beams have been modeled with concentrated rotational springs at the ends. Both members are accepted to be linear in between. The plastic hinge occurrence at the end of members were monitored to observe the frames' failure mechanism.
  • Master Thesis
    Seismic Vulnerability Assessment of Bergama Bedesten
    (Izmir Institute of Technology, 2022) Aktaş, Engin; Hamamcıoğlu Turan, Mine; Turan, Mine; Aktaş, Engin; 02.01. Department of Conservation and Restoration of Cultural Heritage; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology; 02. Faculty of Architecture
    This study aims to document Bergama Bedesten with emphasis on its construction technique and material usage; and assess its structural condition for future seismic action through numerical analysis. The monument (15th -16th century) is unique among the historical trade buildings at the center of Bergama, İzmir. It is revealed that the structure is a rare example by the use of plane triangles as transition elements, the oculi placement in domes, and the thickening application at parts where load-bearing arches integrate into the walls and at the corners. In order to investigate the vulnerability of the building, numerical analysis using the finite element method was conducted in ANSYS software. According to the Turkey Building Earthquake Code (2018), single-mode equivalent earthquake analysis considering the horizontal elastic design spectrum of the site was carried out for x and y directions, separately. The maximum principal stress concentration locations obtained through analyses point vulnerable zones. These were specifically observed on load-bearing arches, on some plane triangles, on the transition zones, at dome parts close to the transition zone and peak level, at the parts where arches integrate to the walls, around top windows, on the west entrance door arch, and on a secondary door arch in the north wall. The method comparing the structural failure mapping and visual structural alterations analysis of architectural restoration with finite element model results, emphasizes that some damaged or altered portions in the current state are in seismically vulnerable spots. Some precautions, further studies and interventions were suggested for these locations.
  • Master Thesis
    The Concept of Equilibrium and Its Effects of Change From Static To Dynamic on Architectural End-Products
    (Izmir Institute of Technology, 1999) İnceköse, Ülkü; İnceköse, Ülkü; Eyüce, Emine Özen; Eyüce, Özen; 02.02. Department of Architecture; 02. Faculty of Architecture; 01. Izmir Institute of Technology
    All of the objectslbuildings on the earth can stand due to their structural orders.Standing of a structural order without suffering any damage (broken down, collapsing ... ) is the result of their state of equilibrium. The most important factor effecting the state of equilibrium of any structural order is the force of gravity.Differantiation in the structural orders formed under this stable effect can be explained by the change in the concept of equilibrium. Therefore, analysing the change in architectural and engineering end-products could only be done by understanding the change in the concept of equilibrium.Scientific developments are the basic factors causing the changes in the concept of equilibrium. Reflections of these developments on concrete products is both in the types of load transfer of structural order and in visual expression of order.Consequently, in the scope of the thesis, depending on developments in the science reflections of the change in the concept of equilibrium on concrete products is tried to be explained by structural and geometrical analses. Expression of these analyses are made through the relationship between equilibrium and movement. It is concluded that the change in the structural orders basing on an acceptance of basic physics that "an object is either stable or movable "; is from structures having no motion to structures having any kind of motion (having tendency to move and/or moving). In other words, it can be said that, this change is from immobile structures having whole connection with the ground, to structures trying to remove from the ground.At the end, in today, it is possible to discuss about solutions having different equilibrium orders that is seen/will be seen basing on scientific developments.Generally it is possible to classify these solutions as solutions that can be expressed by different geometrical orders or solutions towards to be independent from the force of gravity.in the light of these determinations the aim of the thesis is to determine changes in the concept of equilibrium and to analyse their effects on structural end-products and to give some clues about their future effects.Keywords: Structural equilibrium, structural balance, gravity, geometry, energy, structural order.
  • Master Thesis
    Nonlinear Finite Element Analysis of Reinforced Concrete Structures Subjected To Impact Loads
    (Izmir Institute of Technology, 2010) Cağaloğlu, Neriman Çare; Saatcı, Selçuk; Saatcı, Selçuk; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Design of reinforced concrete structures against extreme loads, such as impact and blast loads, is increasingly gaining importance. However, due to the problem.s complicated nature, there exists no commonly accepted methodology or a design code for the analysis and design of such structures under impact loads. Therefore, engineers and researchers commonly resort to the numerical methods, such as the finite element method, and utilize different methods and techniques for the analysis and design. Although each method has its advantages and disadvantages, usually engineers and researchers persist on their method of choice, without evaluating the performance of other methods available. In addition, there is no significant study in the literature comparing the methods available that can guide the engineers and researchers working in the area. This study compares the performance of some numerical methods for the impact analysis and design with the help from actual impact test results in the literature. Computer programs VecTor2 and VecTor3 were selected for nonlinear finite element methodology, which were based on the Modified Compression Field Theory. Impact tests conducted on reinforced concrete beams were modeled and analyzed using these programs. Moreover, same beams were modeled also using a single degree of freedom spring system method. The results obtained from both approaches were compared with each other and the test results, considering their accuracy, computation time, and ease of use.