Sürdürülebilir Kalkınma Amaçları

• 1

• MakaleYalnız künye2017Scopus SJRQ1/r/bayburt/13827
  Experimental determination of cohesion & internal friction angle on conventional concretes

  Pul, Selim; Ghaffari, Amir; Öztekin, Ertekin; Hüsem, Metin; Demir, Serhat

  Various failure criterions have been used for the nonlinear analysis of concrete and reinforced concrete structures. To get more accurate results from the analyses, the selected failure criterion must be appropriate with the characteristics of problem and the assumptions made in the criterion should comply with the characteristics of problem. In this study, an experimental investigation was carried out to determine the cohesion (c) and internal friction angle (?) values, which are in the compressive strength range of 14.4 MPa ≤ fcm cube ≤ 47.0 MPa (2.03 ksi ≤ fcm cube ≤ 6.82 ksi) that are used in failure criterions such as Mohr-Coulomb and Drucker-Prager preferred in end unit analyses for concrete and reinforced concrete structures. Tests are performed by using the direct shear test system, which is designed and produced for this study. Finally, cohesion and internal friction angle were determined between 2.94 and 12.34 MPa (0.43 and 1.79 ksi) and 29.8 and 41.7 degrees, respectively.

  AtıfScopus44·WoS38·OpenAlex36

  İncele
• MakaleAçık Erişim2016Scopus SJRQ1/r/bayburt/13924
  Experimental determination of Drucker-Prager yield criterion parameters for normal and high strength concretes under triaxial compression

  Öztekin, Ertekin; Pul, Selim; Hüsem, Metin

  In this study, parameters which define Drucker-Prager yield criterion were investigated experimentally for both normal strength concrete (NSC) and high strength concrete (HSC) by triaxial compression tests. Total 16 concrete series with different concrete strength were produced. While 8 concrete series were produced as NSC (20 MPa < fcm < 55 MPa), other 8 series were produced as HSC (55 MPa < fcm < 85 MPa). Each series contains 16 specimens. Triaxial compression tests were performed on these concrete specimens. Concrete compressive strength of the specimens were measured under 4 different lateral compression level (0, 1, 2 and 4 MPa). After Mohr circles were drawn by using the data obtained from triaxial compression tests, the values of cohesion were determined between 5 MPa and 13 MPa for NSC and 13 MPa and 19 MPa for HSC. The values of internal friction angle were also obtained between 27° and 34° for NSC, 34° and 39° for HSC from the Mohr circles. The parameters defining the Drucker-Prager yield criterion were determined by using the values of cohesion and internal friction angle. Finally, after some equations were proposed to calculate the parameters by using concrete compressive strength, the validation of these equations were also proved in this study.

  AtıfScopus83·WoS74

  İncele
• MakaleYalnız künye2016Scopus SJRQ2/r/bayburt/13814
  ANN based investigations of reliabilities of the models for concrete under triaxial compression

  Öztekin, Ertekin

  Purpose - A lot of triaxial compressive models for different concrete types and different concrete strength classes were proposed to be used in structural analyses. The existence of so many models creates conflicts and confusions during the selection of the models. In this study, reliability analyses were carried out to prevent such conflicts and confusions and to determine the most reliable model for normal- and high-strength concrete (NSC and HSC) under combined triaxial compressions. The paper aims to discuss these issues. Design/methodology/approach - An analytical model was proposed to estimate the strength of NSC and HSC under different triaxial loadings. After verifying the validity of the model by making comparisons with the models in the literature, reliabilities of all models were investigated. The Monte Carlo simulation method was used in the reliability studies. Artificial experimental data required for the Monte Carlo simulation method were generated by using artificial neural networks. Findings - The validity of the proposed model was verified. Reliability indexes of triaxial compressive models were obtained for the limit states, different concrete strengths and different lateral compressions. Finally, the reliability indexes were tabulated to be able to choose the best model for NSC and HSC under different triaxial compressions. Research limitations/implications - Concrete compressive strength and lateral compression were taken as variables in the model. Practical implications - The reliability indexes were tabulated to be able to choose the best model for NSC and HSC under different triaxial compressions. Originality/value - A new analytical model was proposed to estimate the strength of NSC and HSC under different triaxial loadings. Reliability indexes of triaxial compressive models were obtained for the limit states, different concrete strengths and different lateral compressions. Artificial experimental data were obtained by using artificial neural networks. Four different artificial neural networks were developed to generate artificial experimental data. They can also be used in the estimations of the strength of NSC and HSC under different triaxial loadings.

  AtıfScopus5·WoS5·OpenAlex6

  İncele
• MakaleYalnız künye2015/r/bayburt/15498
  Cıvatalı çelik yapı birleşimlerinde cıvata yerleşim mesafelerinin güvenilirliklerinin monte carlo simülasyon metodu ile araştırılması

  Oztekin, Ertekin

  Cıvatalı çelik yapı elemanı birleşimlerinde, cıvatalar arası uzaklıkların ve cıvataların çelik levha kenarına uzaklıklarının tasarımı yönetmeliklerde belirtilen minimum ve maksimum sınırlar temel alınarak yapılmaktadır. Bu çalışmada cıvatalı birleşimlerdeki cıvatalar arası ve cıvataların birleşim levhası kenarlarına olan mesafelerinin güvenilirlikleri araştırılmıştır. Bu amaçla yükleme türü, cıvata türü, birleşim levhası kalınlığı, değişken olarak alınmıştır. Bu parametrelerin tüm kombinasyonları için gerçekleştirilen güvenilirlik analizlerinde Monte Carlo Simülasyon (MCS) yöntemi kullanılmıştır. Çalışmanın sonucunda elde edilen güvenilirlik indeksi değerleri grafikler ve tablolar halinde sunularak elde edilen sonuçlar ile bazı yönetmeliklerde önerilen değer aralıkları karşılaştırılarak elde edilen bulgular üzerinde değerlendirmeler yapılmıştır. Sonuç olarak geleneksel ve güvenilirlik düzeyi daha yüksek tasarımlar için aynı cıvata aralıklarının kullanımının hatalı olacağı vurgulanmıştır.

  AtıfTR Dizin2

  İncele
• MakaleAçık Erişim2015/r/bayburt/14402
  INVESTIGATION OF RELIABILITIES OF BOLT DISTANCES FOR BOLTED STRUCTURAL STEEL CONNECTIONS BY MONTE CARLO SIMULATION METHOD

  Öztekin, Ertekin

  Design of the distance of bolts to each other and design of the distance of bolts to the edge of connection plates are made based on minimum and maximum boundary values proposed by structural codes. In this study, reliabilities of those distances were investigated. For this purpose, loading types, bolt types and plate thicknesses were taken as variable parameters. Monte Carlo Simulation (MCS) method was used in the reliability computations performed for all combination of those parameters. At the end of study, all reliability index values for all those distances were presented in graphics and tables. Results obtained from this study compared with the values proposed by some structural codes and finally some evaluations were made about those comparisons. Finally, It was emphasized in the end of study that, it would be incorrect of the usage of the same bolt distances in the both traditional designs and the higher reliability level designs.

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  AtıfWoS1·OpenAlex3

  İncele