Akış, Tolga
Loading...
Profile URL
Name Variants
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
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
Main Affiliation
Civil Engineering
Status
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Sustainable Development Goals
3
GOOD HEALTH AND WELL-BEING
1
Research Products
11
SUSTAINABLE CITIES AND COMMUNITIES
5
Research Products
12
RESPONSIBLE CONSUMPTION AND PRODUCTION
2
Research Products
Scholarly Output
45
Articles
29
Citation Count
399
Supervised Theses
13
45 results
Scholarly Output Search Results
Now showing 1 - 10 of 45
Article Citation - WoS: 14Citation - Scopus: 15Yielding of Two-Layer Shrink-Fitted Composite Tubes Subject To Radial Pressure(Springer Heidelberg, 2005) Eraslan, AN; Akis, T; Civil EngineeringYielding of two-layer shrink-fitted composite tubes with axially constrained ends subject to either internal or external pressure is investigated in detail. In the framework of small deformations, a state of plane strain and von Mises yield criterion, analytical expressions are obtained for critical values of the pressure leading to plastic flow. It is shown that, depending on material properties and tube dimensions, different modes of plastic deformation may occur. Yielding may commence at the inner tube or at the outer tube or simultaneously in both tubes. The conditions for different nature of plastic flow are determined. Using analytical expressions obtained for critical values of the parameters and properties of real engineering materials, various numerical examples are handled and the variation of elastic limit pressure with interference and interface radius is explained.Conference Object Improvement of Mechanical Performance in Different Concrete Applications Through Use of Steel Fibers(International Committee of the SCMT conferences, 2016) Baran,E.; Mertol,H.C.; Akis,T.; Civil Engineering; Department of Civil EngineeringThe use of steel fibers improves the brittle characteristics of concrete and provides superior mechanical performance compared to the conventional concrete. Remarkable increase in tensile strength and flexural toughness is obtained when steel fibers are used in conventional concrete, mainly due to the crack arrest effect of these fibers. The use of waste materials, such as scrap tires as a source of steel fibers, as well as the resulting increase in service life and the savings in the life cycle cost make the steel fiber reinforced concrete (SFRC) a sustainable construction material. From this perspective, SFRC offers a strong potential for a more sustainable and more economical alternative to conventional concrete. This paper presents examples of how the addition of steel fibers improves the mechanical performance in two different concrete applications: (1) bond behavior of prestressing strands and (2) flexural behavior of reinforced concrete beams. The first part of the study aimed at investigating the variation in bonding mechanism of prestressing strands when used in plain concrete and in SFRC. Pullout tests were conducted on 12.7 mm diameter prestressing strands embedded in SFRC blocks with four different fiber concentrations. This way, the applicability of the available transfer length and development length formulas for prestressing strands embedded in SFRC was investigated. In the second part of the study, flexural behavior of SFRC beams with various levels of flexural reinforcement ratio was studied. The aim was to identify the influence of steel fibers on the mechanical response of lightly and relatively heavily reinforced SFRC beams. The response of SFRC beams and the companion plain concrete beams were evaluated based on the moment capacity, deformation capacity, and service stiffness. © 2016 International Committee of the SCMT conferences. All rights reserved.Article İKİ KATMANLI DOLU BİR SİLİNDİRİN ELASTİK DAVRANIŞININ FARKLI UÇ VE SINIR KOŞULLARI İÇİN ANALİTİK OLARAK İNCELENMESİ(Turkish Soc thermal Sciences Technology, 2020) Akış, Tolga; Eraslan, Ahmet N.; Civil Engineeringİki katmanlı dolu silindirlerin zamana bağlı termoelastik davranışlarının farklı uç ve sınır koşulları için belirlenmesi amacıyla analitik modeller geliştirilmiştir. Söz konusu silindirler, aralarında mükemmel temas olan ikikatmandan oluşmaktadır. Başlangıçta sıcak olan silindir, yüzeyinden konveksiyon yolu ile sıfır derecelik çevreselsıcaklığa veya önceden daha düşük olarak belirlenen yüzey sıcaklığına ulaşana kadar enerji kaybetmektedir. Tümdurumlarda soğuma yavaş bir biçimde gerçekleştiğinden problemde kuplajsız elastisite teorisinin kullanılması mümkünolmuştur. Genelleştirilmiş düzlemsel şekil değiştirme çözümü elde edilmiş ve bu çözüm, eksenel yöndeki birim şekildeğiştirmeyi sıfıra eşitleyerek düzlemsel şekil değiştirme durumuna ait çözüme indirgenmiştir. Bu çözümlere aitsonuçlar, sınır koşullarının serbest olduğu durumlarda radyal ve teğetsel yöndeki gerilmelerin uç koşullarına göredeğişmediğini göstermiştir. Ancak düzlemsel şekil değiştirme durumunda, eksenel gerilme baskın gerilme olmakta veuçların serbest olduğu duruma göre oldukça yüksek değerlere ulaşmaktadır. Kompozit silindirin eksenel ve radyalyönde yer değiştirmesinin kısıtlanması büyük gerilmelere yol açmasına rağmen ilgili gerilme durumu silindirde akmayayol açmamaktadır.Article Citation - WoS: 2Citation - Scopus: 2Structural Design Optimization of Multi-Layer Spherical Pressure Vessels: a Metaheuristic Approach(Springer, 2019) Akis, Tolga; Azad, Saeid Kazemzadeh; Civil Engineering; Department of Civil EngineeringThis 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.Letter 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 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]Article Citation - WoS: 2Yielding of Radially Pressurized Functionally Graded Long Tubes Based on Von Mises Criterion(Gazi Univ, 2015) Akis, Tolga; Eren, Omur; Civil EngineeringThe 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 - WoS: 23Citation - Scopus: 29On the Elastic-Plastic Deformation of a Rotating Disk Subjected To a Radial Temperature Gradient(Marcel dekker inc, 2003) Eraslan, AN; Akis, T; Civil EngineeringElastic-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 - WoS: 9Citation - Scopus: 10Influence of Cement Replacement by Calcinated Kaolinitic and Montmorillonite Clays on the Properties of Mortars(Springer Heidelberg, 2023) Al-Noaimat, Yazeed A. A.; Akis, Tolga; Civil EngineeringThis study aims to investigate the decomposition and pozzolanic reactivity of two different clays (kaolinitic and montmorillonite) from different origins and to determine their effects after calcination on the properties of cement mortars when used to replace Portland cement partially. Mineralogical and chemical compositions of the clay samples were determined using XRD (X-ray Diffractometer) and XRF (X-ray Fluorescence) tests, respectively. TG-DTA (Thermogravimetry-Differential Thermal Analyses) was used to determine the temperature profiles and the burning temperatures of the clays. The density and fineness of the burnt clays were also determined. In order to investigate the optimum material properties, different burning temperatures and replacement levels were considered. It was found that for all temperatures, the two burnt clays possess good pozzolanic activity. The highest compressive strength and lowest water absorption capacity were achieved when the clay determined as kaolinitic was burned at 700 & DEG;C and with 10% replacement level. While for the clay determined as montmorillonite, the optimum properties were obtained at 700 & DEG;C with a 20% substitution level. Kaolinite had better pozzolanic reactivity than montmorillonite, achieving higher strength performance with lower water absorption when partially replaced with cement. Moreover, it had compressive strength values even higher than plain cement.Article Citation - WoS: 1Citation - Scopus: 2Modeling of Asymmetric Shear Wall-Frame Building Structures(Architectural inst Japan, 2009) Akis, Tolga; Tokdemir, Turgut; Yilmaz, Cetin; Civil EngineeringBased 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.
