Akış, Tolga

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Akis T.
Akis,Tolga
Tolga, Akış
Akış,T.
Akis,T.
T., Akış
Akis, Tolga
Akış, Tolga
Tolga Akış
T., Akis
T.,Akış
Akış T.
T.,Akis
Akiş T.
A.,Tolga
A., Tolga
Tolga, Akis
Akis, T
Job Title
Profesör Doktor
Email Address
tolga.akis@atilim.edu.tr
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output

48

Articles

31

Citation Count

399

Supervised Theses

13

Scholarly Output Search Results

Now showing 1 - 10 of 48
  • Article
    Citation Count: 7
    Evaluation of masonry buildings and mosques after Sivrice earthquake
    (Croatian Soc Civil Engineers-hsgi, 2021) Mertol, Halit Cenan; Tunc, Gokhan; Akis, Tolga; Civil Engineering
    The evaluation of masonry and mosque type structures after the Sivrice Earthquake is presented in this study. Stone masonry buildings exhibited damage such as vertical cracks and splitting at corners, wedge shaped corner failures, diagonal cracking on walls, out-of-plane splitting of walls, and separation of walls from flooring/roofing systems. On the other hand, the separation of flags and caps of minarets was a common example of damage in mosques. Future earthquake damage can be prevented by following design codes and providing adequate supervision for new structures, while strengthening measures are recommended for the existing buildings.
  • Article
    Citation Count: 33
    Elastoplastic response of a long functionally graded tube subjected to internal pressure
    (2005) Eraslan,A.N.; Akis,T.; Civil Engineering
    Plane strain analytical solutions to functionally graded elastic and elastic-plastic pressurized tube problems are obtained in the framework of small deformation theory. The modulus of elasticity of the tube material is assumed to vary radially according to a 2 parametric model in a general parabolic form. The analytical plastic model is based on Tresca's yield criterion, its associated flow rule and ideally plastic material behavior. Exact solutions of field equations for elastic and plastic deformations are obtained. It is shown that the elastoplastic response of the functionally graded pressurized tube is affected notably by the radial variation of modulus of elasticity. It is also shown mathematically that the nonhomogeneous solution presented here reduces to that of a homogeneous one by the appropriate choice of the material parameters. © TÜBİTAK.
  • Article
    Citation Count: 0
    Dikkat Mi Nabız Mı: Apne Sürelerinin Tahmin Edilmesinde Yukarıdan Aşağıya ve Aşağıdan Yukarıya Süreçlerin Bütünleştirilmesine Yönelik Bir Ön Çalışma
    (2023) Alkan, Neşe; Akış, Tolga; Department of Psychology; Civil Engineering
    Serbest dalış performansı gibi bazı aktivitelerde zamanın doğru algılanması hayati önem taşımaktadır. Saniyeler ile ifade edilebilecek görece uzun zaman aralıklarının doğru tahmininin altında yatan kesin mekanizmaların anlaşılması, psikolojide çözülmesi gereken konulardan biridir. Bu amaçla, mevcut çalışmada, prospektif bir paradigma kullanılarak, 25, 50 ve 75 saniyelik apne sürelerinin yordayıcıları incelenmiştir. Çalışmanın verileri, iki deneysel koşulda, on bir serbest dalış sporcusunun hedef apne tahminlerini havada ve suda (daldırılmış) yapmaları yolu ile elde edilmiştir. Katılımcıların kalp atış hızı değerleri, dikkat kontrol kapasiteleri ve duygu durumlarının üç farklı hedef apne tahminindeki doğruluğunun incelendiği bu çalışmada: zaman tahminini etkileyen tek faktörün kalp atış hızı olmadığı; dikkat kapasitesi ve olumlu duygudurumun lineer olmayan bir tarzda zaman tahmininin doğruluğuna etki ettiği; yordayıcı olarak kullanılan bu üç değişkenin, deney koşuluna ve hedef aralığın süresine göre farklı şekilde etkili olduğu ve son olarak, katılımcıların en doğru zaman tahmininin, bu çalışmada kullanılan en uzun zaman aralığı olan 75 saniye suda apne olduğu bulunmuştur.
  • Article
    Citation Count: 2
    Structural Design Optimization of Multi-layer Spherical Pressure Vessels: A Metaheuristic Approach
    (Springer, 2019) Akis, Tolga; Azad, Saeid Kazemzadeh; Civil Engineering; Department of Civil Engineering
    This study addresses the optimum design problem of multi-layer spherical pressure vessels based on von Mises yield criterion. In order to compute the structural responses under internal pressure, analytical solutions for one-, two-, and three-layer spherical pressure vessels are provided. A population-based metaheuristic algorithm is reformulated for optimum material selection as well as thickness optimization of multi-layer spherical pressure vessels. Furthermore, in order to enhance the computational efficiency of the optimization algorithm, upper bound strategy is also integrated with the algorithm for reducing the total number of structural response evaluations during the optimization iterations. The performance of the algorithm is investigated through weight and cost minimization of one-, two- and three-layer spherical pressure vessels and the results are presented in detail. The obtained numerical results, based on different internal pressures as well as vessel sizes, indicate the usefulness and efficiency of the employed methodology in optimum design of multi-layer spherical pressure vessels.
  • Article
    Citation Count: 2
    Yielding of Radially Pressurized Functionally Graded Long Tubes Based on Von Mises Criterion
    (Gazi Univ, 2015) Akis, Tolga; Eren, Omur; Civil Engineering
    The elastic behaviour of functionally graded long tubes with axially constrained ends subject to either internal or external pressure is investigated analytically. The modulus of elasticity and the yield limit of the tube material are assumed to vary radially in nonlinear forms. Making use of von Mises yield criterion, the effect of grading parameters on the yielding behavior of the tube is investigated and it is observed that for both pressure cases, the plastic flow may commence at the inner surface, at the outer surface or simultaneously at both surfaces depending on the functionally grading parameters.
  • Article
    Citation Count: 20
    On the elastic-plastic deformation of a rotating disk subjected to a radial temperature gradient
    (Marcel dekker inc, 2003) Eraslan, AN; Akis, T; Civil Engineering
    Elastic-plastic stress distribution in a nonisothermal rotating annular disk is analyzed by the use of Tresca and von Mises criteria. An energy equation that accounts for the convective heat transfer with a variable heat transfer coefficient is modeled. For a given angular velocity, the steady temperature distribution in the disk is obtained by the analytical solution of the energy equation. Tresca yield criterion and its associated flow rule are used to obtain the analytical stress distributions for a linearly hardening material. A computational model is developed to analyze elastic-plastic deformations of the disk using von Mises yield criterion and its flow rule. This model incorporates Swift's hardening law to simulate linear as well as nonlinear hardening material behavior. It is shown that the stress distribution in the disk is affected significantly by the presence of the temperature gradient.
  • Article
    Citation Count: 2
    Modeling of Asymmetric Shear Wall-Frame Building Structures
    (Architectural inst Japan, 2009) Akis, Tolga; Tokdemir, Turgut; Yilmaz, Cetin; Civil Engineering
    Based on the conventional wide column analogy, two different three-dimensional shear wall models for open and closed sections are proposed. These approximate models are verified in comparison to not only the results available in the literature but also the ones obtained by Using models containing shell elements. With the help of these new models five different groups of shear wall-frame structures with different floor plans and different heights are analyzed. The first three natural vibration periods are determined and time history analyses are performed. The results Of these computations are observed to be in good agreement with those obtained by detailed models containing shell elements.
  • Review
    Citation Count: 0
    Boşluklu perde duvar sistemlerin serbest titreşim periyotlarının farklı yöntemlerle hesaplanması
    (2003) Akış, Tolga; Coşkun, Safa Bozkurt; Civil Engineering
    Çok katlı betonarme yapılarda kullanılan boşluklu perde duvarlar, özellikle deprem dayanımları açısından sıkça tercih edilen yapı sistemleridir. Dayanım ve rijitlik bakımından olumlu özelliklere sahip boşluklu perde duvarların, boşluksuz perde duvarlara göre daha sünek davrandığı bilinmektedir. Herhangi bir yapısal sistemin deprem davranışını belirleyen en önemli parametreler sistemin doğal modları ve bu modlara ait periyotlardır. Bu çalışmada, daha önce sınır eleman yöntemi kullanılarak modellenmiş ve serbest titreşim periyottan elde edilmiş bir boşluklu perde duvar sistemin, gerilme elemanlarının kullanıldığı sonlu elemanlar yöntemi ve çubuk elemanların kullanıldığı geniş kolon benzeşimi yöntemi kullanılarak serbest titreşim periyotları bulunmuştur. Analizlerden çıkan sonuçlar karşılaştırılmıştır.
  • Letter
    Citation Count: 0
    Discussion of the article "Approximate solution of limit angular speed for externally loaded rotating solid disk" by S. Bhowmick, D. Misra and NK Saha [Int J Mech Sci 2008;50:163-74]
    (Pergamon-elsevier Science Ltd, 2008) Eraslan, Ahmet N.; Akis, Tolga; Civil Engineering
    [No Abstract Available]
  • Letter
    Citation Count: 0
    Amendments on "Application of Mises yield criterion to rotating solid disk problem" by N. Aleksandrova [Int. J. Eng. Sci. 51 (2012) 333-337]
    (Pergamon-elsevier Science Ltd, 2012) Eraslan, Ahmet N.; Akis, Tolga; Civil Engineering
    [No Abstract Available]