Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/3

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30 Ekim 2020 Ege Denizi Depreminin Kabuk Deformasyonuna Etkisinin Tusaga-aktif Verileri ile İncelenmesi
(Gumushane University, 2024) Baş, İ.Ç.; Abbak, R.A.
The TUSAGA-Active (Turkish National Continuous Operating Reference System) is available for commercial and academic studies with 168 fixed GNSS (Global Navigational Satellite Systems) stations. Its capability to provide high-accuracy data facilitate to monitor deformations in engineering structures resulting from crustal movements. On October 30, 2020, an earthquake with a magnitude of ML = 6.6 (MW = 6.9) struck the Aegean Sea at 14.51 local time. The aim of the study is that TUSAGA-Active stations located within the earthquake-affected area are thoroughly examined to detect any crustal deformations caused by this seismic event. As part of this analysis, deformation directions and magnitudes were determined for stations AYD1, CESM, DIDI, IZMI, KIKA, and SALH. RINEX data from 15 days before the earthquake date and 11 days after were processed using CSRS-PPP (Canadian Spatial Reference System Precise Point Positioning Service) and OPUS (Online Positioning User Service), which are internet-based GNSS services. The results of this analysis revealed that the CESM station experienced the most significant displacement, averaging 57.39 mm in the north direction according to the CSRS-PPP service. Similar results were obtained from the OPUS service data. © 2024, Gumushane University. All rights reserved.
Citation - Scopus: 1
Achievable Rate of Noma-Based Cooperative Communication Systems With Best Relay Selection Over Cascaded Rayleigh Fading Channels
(IEEE, 2020) Özdemir, Özgür
In this paper, the achievable rate analysis of NOMA-based cooperative communication systems with best relay selection is studied. The cascaded Rayleigh fading channels are considered since investigations have shown that cascaded channel structure agree better with mobile network models such as inter-vehicular communication systems. A cooperative network where a source terminal communicates with a destination directly and through a selected relay among K relays is considered and the achievable average rate of this system using NOMA is found by computer simulations. The obtained results for cascaded Rayleigh fading channels in case of decode and forward protocol have shown that the average rate is decreased as the cascading degree increases. It has been also seen that for a given cascading degree the average rate performance of the system is increased when the number of total relays is increased.
Citation - WoS: 6
Citation - Scopus: 9
Ağaç-tohum Algoritmasının Cuda Destekli Grafik İşlem Birimi Üzerinde Paralel Uygulaması
(2018) Çınar, Ahmet Cevahir; Kıran, Mustafa Servet
Son yıllarda toplanan verinin artmasıyla birlikte verimli hesaplama yöntemlerinin de geliştirilmesi ihtiyacı artmaktadır. Çoğunlukla gerçek dünya problemlerinin zor olması sebebiyle optimal çözümü garanti etmese dahi makul zamanda yakın optimal çözümü garanti edebilen sürü zekâsı veya evrimsel hesaplama yöntemlerine olan ilgi de artmaktadır. Diğer bir açıdan seri hesaplama yöntemlerinde verinin veya işlemin paralelleştirilebileceği durumlarda paralel algoritmaların da geliştirilmesi ihtiyacı ortaya çıkmıştır. Bu çalışmada literatüre son yıllarda kazandırılmış olan popülasyon tabanlı ağaç-tohum algoritması ele alınmış ve CUDA platformu içerisinde paralel versiyonu geliştirilmiştir. Algoritmanın paralel versiyonunun performansı kıyas fonksiyonları üzerinde analiz edilmiş ve seri versiyonunun performansı ile karşılaştırılmıştır. Kıyas fonksiyonlarında problem boyutluluğu 10 olarak alınmış ve farklı popülasyon ve blok sayıları altında performans analizi yapılmıştır. Deneysel çalışmalar algoritmanın paralel versiyonunun algoritmanın seri sürümüne göre bazı problemler için 184,65 kata performans artışı sağladığı görülmüştür.
Analysis of Factors Affecting Travel Costs in Beyşehir Lake National Park
(Tekirdag Namik Kemal University, 2022) Karakayacı, Zuhal; Karakayacı, Özer; Polat, Ahmet
Milli parklar sahip olduğu doğal, kültürel ve tarihi değerlerle rekreasyonel ve turizm amaçlı olarak değerlendirilmektedir. Türkiye’nin ikinci büyük milli parkı olan Beyşehir Gölü Milli Parkı da farklı zenginliklerle birçok insanın ziyaret ettiği yerlerden biridir. Milli parklar rekreasyon ve turizm amacıyla kullanıldığında, kullanıcılara bir maliyet getirmektedir. Seyahat, bir rekreasyonel faaliyet için tamamlayıcı bir nitelik taşımaktadır, çünkü bu faaliyetin gerçekleşebilmesi için söz konusu alana seyahat etmek gerekmektedir. Bu kapsamda, çalışmada Beyşehir Gölü Milli Parkı’nın seyahat maliyeti ve buna etki eden faktörleri incelenmiştir. Beyşehir Gölü Milli Parkı içinde bulunan çeşitli rekreasyon yerleri için ortalama seyahat maliyeti 252.97 TL, kişi başına düşen seyahat maliyeti 74.93 TL olarak hesaplanmıştır. Seyahat maliyetini etkileyen faktörleri incelemek için ziyaretçilerin seyahat maliyetleri yarı logaritmik regresyon modeliyle analiz edilmiştir. Bağımlı değişken seyahat süresince yapılan harcamaların toplamından oluşmakta, seyahat maliyetini etkileyen faktörler olarak, yaş, eğitim, medeni durum, gelir, geliş sıklığı, geliş amacı, geliş mesafesi gibi değişkenler alınmıştır. Analizlerde kullanılan; gelir, eğitim durumu, medeni durumun ‘’evli’’ olması, parka bir defadan fazla gelmiş olma, parka gelinen mesafe, parkı ziyaretin esas amaç olması ve parkta geçirilen zaman faktörleri ile seyahat maliyeti arasında pozitif bir ilişki bulunmaktadır. Yaş, parka geliş sıklığı ve parka şahsi araçla ulaşım sağlamış olma faktörleriyle seyahat maliyeti arasında ise negatif bir ilişki tespit edilmiştir. Seyahat maliyeti analizlerinde bu faktörlerin ele alınması rekreasyon amacıyla kullanılan alanların ekonomik anlamda değerlendirilmesinde yarar sağlayacaktır. Bir ülkenin önemli doğal kaynağı olan milli parkların ekonomik olarak ta değerlendirilerek milli gelire katkı sağlaması gerçekleştirilmelidir. Bu amaçla, milli parkları turizm faaliyetleri açısından sürdürülebilir hale getirecek çalışmalar doğayı koruyarak yapılmalıdır. Bu çalışmada tespit edilen seyahat maliyetini etkileyen faktörler de dikkate alınarak ilgili birimler tarafından programlar planlanmalıdır.
Arazi Toplulaştırma Projelerinde Parsel Şekil Değişiminin Nicel Değerlendirmesi: Konya İli Çumra İlçesi Abditolu Mahallesi Örneği
(Gumushane University, 2021) Ertunç, E.
Land consolidation (LC) are projects that combine scattered and fragmented parcels, improving parcel shapes, and enabling the development of irrigation, drainage and road services for landowners. Improving existing parcel shapes is one of the most important benefits of Land Consolidation projects. There are many indexes that determine the parcel shape change before and after land consolidation. These are Shape Index (SI), Fractal Size Index (FD), Area Shape Factor (AFF), Shape Factor (FORM), Area Perimeter Ratio (APR), Square Pixel Scale (SqP) and Compactness Index (Icmp). These indexes are used in the literature to quantitatively measure the suitability of parcel shapes for modern agriculture. In this study, parcel shape changes pre-consolidation and post-consolidation have investigated by using the data of Abditolu land consolidation project in Çumra district of Konya. Therefore, SI, FD, AFF, FORM, APR, SqP and Icmp, which are among the shape index indicators, have used. As a result of the study; FD, SI, AFF, FORM, SqP, APR and Icmp average values before LC are 1.3579, 1.8486, 0.0424, 0.5334,-0.7819, 6.5530 and 0.5334, respectively; after the LC, it has calculated as 1.3084, 1.3912, 0.0465, 0.5848,-0.8478, 4.9320 and 0.5848. According to the results, there has a general improvement in parcel shapes before and after the LC. FD, SI, FORM, Icmp indexes better reflected parcel shape change before and after LC. © 2021, Gumushane University. All rights reserved.
Behavior of Frictional Rock Bolt and Steel Arch Support Systems in Longwall Gateroads and Their Performance Analyses
(Baski, 2023) Özkan İ.; Mesutoğlu M.; Aydemir F.S.M.
A pilot study was conducted to investigate the applicability of alternative rock bolts to the steel arches support system used in the material gallery (gateroads) of TKİ-GLİ Ömerler underground mine A6 longwall panel. This study was supported by TUBITAK (116M698) and TKI. Six separate pilot application and monitoring zones are planned in an area of 145 meters in the middle of the material gallery. A pilot application was carried out with different rock bolts in four areas of 25 meters each. In the other two regions, the existing steel arches used in the mine were used. In addition, measurement stations for performance analyses have been established in these regions. In this paper, only the measurement results of steel arches (DMRB) and friction (swellex) rock bolt (SWLX) support systems prepared in the pilot application area will be presented. It has been determined that friction rock bolts (SWLX) reduce the deformations in the gateroad roof by approximately 58% compared to the steel arch (DMRB) support system and make the gateroad safer. © 2023 IMCET 2023 - Proceedings of the 28th International Mining Congress and Exhibition of Turkey. All rights reserved.
Betonda Atık Vermikülit Kullanımının Betonun Mineralojik ve Kimyasal Yapısına Olan Etkisinin İncelenmesi
(Gumushane University, 2022) Karakaya Harmanci, F.N.; Soğancioğlu Kalem, M.
Today, new approaches are emerging regarding the recycling of waste materials and their use in building materials. With the reuse of these wastes, important environmental problems are avoided and the raw materials to be used in the production of building materials are also saved. From this point of view, within the scope of this study, it is aimed to evaluate the waste vermiculite mine, which is an important environmental problem and has not yet found an evaluation area, instead of aggregate in the concrete. In this context, the characterization of waste vermiculite (AVK) replaced with fine aggregate and the chemical and mineralogical compositions of the obtained concrete samples were revealed by SEMEDS, FTIR and XRD analyzes, and the chemical and mineralogical changes in the structure of the concrete were associated with the compressive strength of the concrete. According to the results obtained, the decrease in the compressive strength of the concrete with the increase of the waste vermiculite dose and the bound functional O-H groups seen in the chemical structure of the concrete show that the concrete mixture needs extra water. However, as a result of the obtained results, it has been shown that concrete containing low doses of waste vermiculite can be used in structural areas where the compressive strength is not important. © 2022, Gumushane University. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Classification of Mammography Images by Transfer Learning
(IEEE, 2020) Solak, Ahmet; Ceylan, Rahime
Breast cancer is the most common cancer type in women worldwide. Diagnosis and early detection of cancer by mammography images are of great importance in cancer treatment. The use of deep learning in Computer Assisted Diagnostic systems has gained a great momentum especially since 2012. In this study, benign and malignant mass images were reproduced with data augmentation and the data sets obtained were classified with deep learning networks. In this study, a scratch Convolutional Neural Network (CNN) architecture was created and transfer learning was realized with different network models which trained on IMAGENET images. In the transfer learning section, separate training results were obtained by performing feature extraction and fine tuning of network parameters. As a result of the study, the best results were obtained with MobileNet, NASNetLarge and InceptionResNetV2 models which are used in transfer learning models.
Classification of Medical Thermograms Using Transfer Learning
(IEEE, 2020) Örnek, Ahmet Haydar; Ceylan, Murat
Thermal imaging has been used for decades to monitor the health status of neonates as an non-invasive and non-ionizing imaging technique. Applications such as thermal asymmetry and disease analysis can be performed by applying deep learning methods to thermal imaging technique. However, thousands of different images are needed to perform analyzes with deep learning methods. It takes many years to create data sets with thousands of different images due to feeding time, medication time and instant baby care in the neonatal intensive care unit. In this study, a unhealthy-healthy classification was performed using thermal images obtained from the Selcuk University, Faculty of Medicine, Neonatal Intensive Care Unit for one year. Transfer learning method has been used to overcome the lack of data problem. When VGG16 model was used for transfer learning, the results were obtained as 100% sensitivity and 94.73% specificity. This result shows that thermal imaging and transfer learning method can be used in early diagnosis of diseases.
Citation - WoS: 1
Citation - Scopus: 1
Çoklu İHA’larla Kısıt Tatmin Problemi Temelli Çok Amaçlı Görev Planlaması
(Gazi University, Faculty of Engineering Architecture, 2025) Atay, Yılmaz; Ayvaz, Emre; Babaoğlu, İsmail
İnsansız hava araçlarının dahil olduğu çoklu görev planlama problemleri; zamana bağlı görevler ve çeşitli türdeki araçların sensör, konum, yakıt, faydalı yük vb. farklı yetenek ve kısıtlarına bağlı olarak ne tür görevleri yapabileceğinin belirlenmesini ve bunların planlamasını ifade eder. Bu problem, Kısıt Tatmin Problemi (KTP) olarak modellenebilmektedir. Zamansal KTP (ZKTP) ise ardışıl görevlerin, zamansal anlamda görev ikililerine bölünerek KTP üzerine inşasını modeller. Bu işleme bağlı olarak görev isterleri ile İnsansız Hava Aracının (İHA)’nın yetenekleri arasındaki statik ve dinamik kısıtlara bağlı olarak gerçekleştirebilecek eylemler ile ilgili baskın bir çözüm kümesi aranır. Böylece görevler ile mevcut İHA’ların yetenekleri arasındaki ilişki, zamansal boyutta irdelenerek çok amaçlı problemleri optimize eden aday çözümler bulunur. İyileştirilmiş ZKTP (İZKTP) yönteminde KTP’deki aç gözlü yaklaşım yerine, etki alanındaki en yüksek puana sahip İHA’nın göreve atanması önerilmiştir. Ek olarak, iyileştirilmiş ileri kontrol yöntemiyle bir sonraki görevin etki alanındaki İHA'ların gerçek zamanlı konumlarına ve zamanlarına göre atama durumu değerlendirilebilmektedir. Bu çalışmada, yakıt tüketimini ve toplam havada kalma süresini en aza indiren uygun bir çözüm kümesinin KTP ile aynı zaman karmaşıklığı içinde bulunması amaçlanır. Burada, zamansal kısıt tatmin modeli gerçeklenmiş ve çeşitli görevlerde karmaşıklığı aşamalı olarak değiştirilerek geri izleme (Backtracking), ileri kontrol (Forward Checking), yay tutarlılığı (Arc Consistency), düğüm tutarlılığı (Node Consistency) yöntemleriyle önerilen yaklaşımın performansı, deneysel çalışmalarla doğrulanmıştır. Bu kapsamda yapılan deneyler iki farklı aşamayı içermektedir. İlk aşamada, çeşitli yetenek ve kısıtlara sahip İHA'ların farklı isterleri olan görevlere atanmasını içeren farklı simülasyonlar gerçekleştirilmiştir. Buradaki simülasyonlarda olası gerçek senaryolardan esinlenen sentetik veriler kullanılmıştır. İkinci aşamada ise atamalar sonrası dinamik programlama temelli etki alanı güncellemesiyle görev ikililerinin zaman pencerelerinde değişen süreçleri takip eden düğüm kontrolü, geri izleme, ileri kontrol ve yay tutarlılığı yaklaşımları kullanılmıştır. Önerilen KTP ile gerçekleştirilen testler sonucu sekiz farklı görev içeren iş paketinde, KTP ile benzer zaman karmaşıklığında daha uygun maliyet ve zaman çıktıları elde edilmiştir. Testler kapsamında 64 farklı görev içeren bir problem için önerilen yöntem, standart KTP’ye göre12 adet daha az İHA kullanılmasını sağlayarak önemli bir performans artışına ulaşmıştır.
Citation - WoS: 5
Citation - Scopus: 8
Comparison of Linear Discriminant Analysis, Support Vector Machines and Naive Bayes Methods in the Classification of Neonatal Hyperspectral Signatures
(Institute of Electrical and Electronics Engineers Inc., 2021) Cihan, Mücahit; Ceylan, Murat
Hyperspectral imaging (HSI) is an imaging method that enables to obtain a large number of two-dimensional images in a wide wavelength range in the electromagnetic spectrum band. HSI has an important potential in biomedical applications as it provides diagnostic information about tissue physiology, morphology and composition. In this study, spectral signatures of unhealthy and healthy neonates were extracted using HSI method. Then, data statistics (minimum, maximum, mean, median and standard deviation) of these signatures were obtained and classified with Linear Discriminant Analysis, Support Vector Machines and Naive Bayes Methods. After the classification processes, the best result was achieved using Linear Discriminant Analysis with 90.63% accuracy, 87.50% sensitivity and 93.75% specificity. © 2021 IEEE.
Citation - Scopus: 2
Comparison of Performance Analysis of a Moment Resisting Framed Structure According To Tbdy 2018 and Asce 41-17
(TUBITAK, 2021) Jamal, Rohullah; Yüksel, Süleyman Bahadır
Due to its simplicity, nonlinear static procedure (NSP) or pushover analysis has been using for the determination of the nonlinear performance of structural and non-structural members. While modeling the determination of the nonlinear properties and deformation capacities for each component of the structure should be determined. Pushover analysis is carried out for either user-defined nonlinear hinge properties or defaulthinge properties, available in some programs based on the TBDY 2018 and ASCE 41-17 standards. Assigning the incorrect default-hinge properties may lead to unreasonable displacement capacities for existing structures. In this study the performance analysis of a single span structure was performed according to TBDY 2018 and ASCE 41-17 codes and the results were compared. Number of stories of the structures were changed for the parametric study. Capacity curves have been obtained as a result of the analysis performed on the building systems. The peak displacement amount calculated according to ASCE 41-17 was obtained more than the peak displacement amount calculated according to TBDY 2018. The amount of base shear force and story shear forces calculated according to TBDY 2018 has been obtained more than ASCE 41-17. The most effective parameters for the plastic hinge properties are plastic hinge length and transverse reinforcement spacing. The results of analyses obtained from the TBDY 2018 and ASCE 41-17 codes show that the structural performance depends on the number of vertical loads, effective stiffness of the structural members and plastic hinge properties. © 2021, TUBITAK. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 4
A Comparison of Rans-Based Turbulence Modeling and Piv Experiments for Flow Over a Simplified Road Vehicle
(Gazi Universitesi, 2023) Aksoy, M.H.; Okbaz, A.; Yaǧmur, S.; Doǧan, S.
The aerodynamic forces on road vehicles and flow structures around them result from complex interactions between fluid and structure. Ahmed body is a simplified car model created to demonstrate and simplify the flow around real-size ground vehicles. In this study, the flow structure on the wake region of Ahmed body with different slant angles (Θ=15°, 25°, and 35°) was investigated. Experimental studies were conducted in a water channel by Particle Image Velocimetry (PIV). The freestream velocity was set to 0.2 m/s, and the Reynolds number defined by the characteristic length of the Ahmed body was 4.16×104 for Computational Fluid Dynamics (CFD) and PIV experiments. CFD simulations were performed using three different turbulence models: realizable k-ϵ, RNG k-ϵ, and SST k-ω, and the results were compared to experiments. The results are presented with different flow features such as time-averaged velocity vectors and velocity contours, streamline topology, vorticity, and Turbulence Kinetic Energy. The closest results to the experiments were obtained by the SST k-ω turbulence model for all slant angles of the Ahmed body. In addition, the drag coefficient is found to be 0.37 for all slant angles analyzed by SST k-ω turbulence models, which are also close to the results in the literature. © 2023 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
Comprehensive Comparison of Deep Learning Architectures for Stroke Classification From CT Images
(Institute of Electrical and Electronics Engineers Inc., 2025) Yanar, Erdem; Kutan, Furkan; Ayturan, Kubilay; Kutbay, Uǧurhan; Hardalaç, Firat; Dogan, Mehmet Selman; Algin, Oktay
Stroke, a leading cause of death and permanent disability worldwide, is classified into ischemic and hemorrhagic types. Accurate and timely classification from CT images is critical for effective treatment in emergency care. This study compares modern deep learning models ResNet, ViT, EfficientNet, Inception, ResNeXt, MobileNet, ConvNeXt, ConvNeXtV2, and DaViT - for classifying stroke (ischemic, hemorrhagic) and non-stroke cases from CT images. Models were evaluated using the 2021 Teknofest stroke dataset based on accuracy, precision, specificity, and computational efficiency. Results show that while advanced models like ViT and ConvNeXtV2 offer high performance, lightweight architectures such as MobileNet (F1-score: 97.59%) are clinically viable and ideal for resource-limited environments. © 2025 Elsevier B.V., All rights reserved.
Citation - Scopus: 1
Design of Adaptive Speed Control System With Model Predictive Control
(Institute of Electrical and Electronics Engineers Inc., 2021) Budak, S.; Sungur, C.; Terzioğlu, H.
Model predictive control used in adaptive speed control systems can make inferences by predicting the future like a driver, taking precautions, imposing restrictions in terms of safety, comfort and fuel consumption just like the driver, and giving different degrees of importance to these restrictions. The importance of choosing appropriate parameter values used in model predictive control design was emphasized with graphics in the simulation study. When the appropriate parameter values are selected, speed and distance control gave the best results according to the results obtained. © 2021 IEEE.
Citation - WoS: 5
Citation - Scopus: 4
Design, Manufacture and Thermal Analysis of a Single Pass Solar Air Collector at Different Mass Flow Rates
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2020) Darıcı, Selçuk
Solar air collectors are generally used for drying industrial and agricultural products or for space heating. Nowadays solar energy is paid more attention due to decrease in fossil fuels and increase in energy prices. In this study, a single pass, forced convective solar air collector has been designed, manufactured and analysed experimentally under climatic conditions of Konya/Turkey. Experiments have been conducted at three different mass flow rates, on different days and under clear weather conditions. Hourly variation of solar radiation, inlet and outlet air temperatures, glass cover temperature, absorber plate temperature and thermal efficiency of the solar air collector have been examined by using the experimental data obtained. It is seen that with the increase in mass flow rate, temperature of the air at the outlet of the collector decreases while thermal efficiency of the collector increases.
Dual-Fed Wideband Mimo Antenna System Design for 5g Applications With Increased Gain With Superstrate
(Institute of Electrical and Electronics Engineers Inc., 2021) Yerlikaya, Mehmet; Gültekin, Seyfettin Sinan
In this study, a compact microstrip MIMO antenna system design with broadband for fifth generation (5G) mobile applications, also known as the next generation, is presented. The proposed antenna system consists of two identical log-periodic dipole antennas (LPDA) placed at an angle of 90° to each other. LPDAs, each consisting of 5 element arrays, are designed with Rogers RT5880 dielectric material with a thickness of 0.508mm and a relative permeability of 2.2. The total size of the MIMO antenna system is determined as 20x20 mm2, where each LPDA's size is 4.15x13 mm2. The proposed antenna system offers impedance bandwidth in the 28 GHz resonance and frequency range of 26.2-30.4 GHz. However, an isolation level above 25 dB was achieved without the need for any additional structure between MIMO elements. To increase the gain value, a superstrate with 1.52 mm height and relative permeability of 3 was also added on the MIMO antenna system. Thus, a gain increase of over 50% was achieved for the whole operating band with this superstrate. With this top layer added, an increase of over 50% has been achieved in the recommended antenna gain for the entire operating band. All the designs and simulations in the study were carried out with the moment based HyperLynx 3D EM package program. © 2021 IEEE.
Citation - Scopus: 3
Effect of Confining Reinforcement and Axial Load Level on Curvature Ductility and Effective Stiffness of Reinforced Concrete Columns
(TUBITAK, 2020) Foroughi, Saeid; Jamal, Rohullah; Yüksel, S. Bahadır
The correct estimate of curvature ductility of reinforced concrete members has always been an attractive subject of study as it engenders a reliable estimate of the capacity of buildings under seismic loads. In this study, the effect of the material model, axial load and transverse reinforcement ratio on the behavior of reinforced concrete columns were analytical investigated. Squared cross-section column models have been designed. The behaviors of the columns were evaluated from the moment-curvature relation by taking the nonlinear behavior of the materials into account. The moment-curvature relationships for different axial load levels and transverse reinforcement ratios of the reinforced concrete column cross-sections were obtained considering the Mander confined model. The examined effects of the parameters on the column behavior were evaluated in terms of the strength of the cross-section, ductility and effective stiffness. In the designed column cross-sections, different parameters effecting the moment-curvature relationships, ductility and effective stiffness were calculated and compared. It is observed that the variation of the axial load and transverse reinforcement ratio have an important effect on the moment-curvature behavior, ductility and effective stiffness of the reinforced concrete columns. Although the effective stiffness of the cracked section is not constant, it varies depends on parameters such as the confining reinforcement and axial force acting on the section. © 2020, TUBITAK. All rights reserved.
The Effect of Coupled Beam Models in Buildings Where Earthquake Loads Are Fully Resisted by R/C Shear Walls on Structural Performance
(TUBITAK, 2021) Özer, Ömer; Yüksel, S. Bahadır
Reinforced concrete shear walls around the stairs and elevator shafts, which are at the core of the structures where earthquake loads are fully resisted R/C shear walls, are generally connected to each other with coupling beams. The aim of this study is to examine the effects of different reinforced concrete coupling beam types and analysis models whose earthquake loads are fully resisted by R/C shear walls on the performance of the building. In this study, nonlinear pushover analysis was performed for each R/C coupling beam model according to the ground acceleration of the Istanbul Ataturk Airport region according to the Turkish Building Earthquake Code (2018) of the 16-storey building model, which uses fully shear walls as vertical carrier. When the analysis results are examined, it has been seen that different reinforced concrete coupling beam types have serious effects on structural performance targets. © 2021, TUBITAK. All rights reserved.
Effect of Fractal Dimension of Blocks on the Shear Strength of Blocky Pyroclastic Rocks
(TMMOB Chamber of Geological Engineers, 2021) Avşar, Elif
In this study, the relationships between shear strength of a blocky rock mass consisting of pyroclastic deposits and the fractal dimension of the blocks within the rock mass were investigated. Within the scope, triaxial shear tests were performed on specimens extracted from a blocky pyroclastic rock mass that defined as “bimrock” in terms of jeo-mechanical description. Thereby, cohesion (c) and internal friction angle (?) values of the rock mass were determined. Fragmentation fractal dimension (DF ) and roughness fractal dimension (DR ) values of the blocks within in the rock mass were calculated through the fractal dimension solutions and digital image processing analysis. In addition, uniaxial compressive strength of the rock and the matrix component of this rock mass were determined. The results revealed that there are positive and negative linear relationships between DR and c, ? and between DF and c, ? pairs. It is determined that, while the values of both DR and DF increase, the values of ? increase and vice versa for cohesion. The increase of ? with the increase of DR is an indication that the friction also increases by applied shear stresses due to the increase in the roughness of the block surfaces. Finally, the increasing of DR yielded an increase in the sum of the surface areas of the contacts between the matrix and blocks. Thus, the cohesion decreases due to the probable increase of weakness zones that loosen the rock mass. © 2021, TMMOB Chamber of Geological Engineers. All rights reserved.

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