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Yayın Energy dissipation characteristics of slab type buildings with special connectors(National Technical University of Athen, 2015-05-25) Şenol, Erkan; Dindar, Ahmet Anıl; Yüksel, Ercan; Karadoğan, Hüseyin FarukThe latest developments in the construction technologies and the materials facilitated the practicing engineers to go higher and energy-efficient buildings. However, the safety of the buildings and the residents has been an issue all the time. This is not an exception for the precast structures. The advantages of the precast elements are the quality assurance and the rapid erection on the site and challenged by the connection details and their performances during the extreme loading cases such as earthquakes. The utilization of a special mechanical connection of the precast members have been in the focus of the recent works in Istanbul Technical University (ITU-STEELAB). The prototypes of the proposed special connectors, called as cushion, were tested in STEELAB in order to determine the mechanical properties such as lateral and axial stiffness and the failure modes. Once the properties were determined, a hypothetical building of single story multi-bay slab type structure was modeled in the computer framework capable of substituting various parametric values into the model, processing and extracting the results for statistical analysis, SAMA. SAMA is developed based on the use of SAP 2000 OAPI functions called in MATLAB and Python scripts. In the hypothetical model, the cushions were modeled as link elements and placed between all the precast elements including foundation-cladding interface. Extensive non-linear time-history analysis was conducted to identify the damage localization by comparing the energy dissipation at each mechanical connector under ground motion records selected according to focal distance, site conditions and intensity. The preliminary results reveal that the cushions are effectively dissipating a significant amount of energy and mitigating the collapse of the precast elements. The more detailed conclusions will be discussed in the near future.Yayın VİSKON-RS : Uzaktan algılama ile hızlı afet hasar analiz yazılımı(IEEE, 2015-06-19) Kahraman, Fatih; İmamoğlu, Mümin; Özcan, Büşra Yüksel; Huruoğlu, Cengiz; Alasağ, Tolga; Gemici, Ömer Faruk; Hocaoğlu, Muhammet A.; Ateş, Hasan FehmiAfet sonrası, acil müdahale ekiplerinin yönlendirilmesi ve iyileştirme çalışmalarının planlanması amacıyla hızlı hasar değerlendirmesine ihtiyaç duyulmaktadır. Bu çalışmada, AFAD ihtiyaçları doğrultusunda uzaktan (uzay/hava) algılama teknolojileri ile elde edilen görüntülerin afet hasar analizinde kullanılmasına yönelik VİSKON-RS yazılımı geliştirilmiştir. Geliştirilen yazılım; deprem, sel ve orman yangını gibi afet türlerinin hasar analizlerine özelleşmiş uygulamalar içermektedir. Ayrıca genel görüntü analizinde kullanılabilecek değişiklik analizi, eğitimli/eğitimsiz sınıflandırma, nesne tabanlı görüntü analizi ve doku analizi gibi uygulamalar yazılıma entegre edilmiştir. VİSKON-RS yazılımın temel amacı, afet sonrası uzaktan algılama verilerinin, açılması, işlenmesi, analiz edilmesi, sonuçların sergilenmesi ve karar destek sistemlerine aktarılması adımlarını içeren bütünleşik bir yazılım çözümü sunmaktır.Yayın Uni-axial behavior of energy dissipative steel cushions(Techno Press, 2018-06-25) Özkaynak, Hasan; Khajehdehi, Arastoo; Güllü, Ahmet; Azizisales, Faraz; Yüksel, Ercan; Karadoğan, Hüseyin FarukSeismic excitations may impart a significant amount of energy into structures. Modern structural design attitudes tend to absorb some part of this energy through special dissipaters instead of heavy plastic deformations on the structural members. Different types of dissipater have been generated and utilized in various types of structures in last few decades. The expected earthquake damage is mainly concentrated on these devices and they may be replaced after earthquakes. In this study, a low-cost device called energy dissipative steel cushion (EDSC) made of flat mild steel was developed and tested in the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University (ITU). The monotonic and cyclic tests of EDSC were performed in transversal and longitudinal directions discretely. Very large deformation capability and stable hysteretic behavior are some response properties observed from the tests. Load vs. displacement relations, hysteretic energy dissipation properties as well as the closed form equations to predict the behavior parameters are presented in this paper.Yayın Analyses of seismic deformation at the Kibyra Roman stadium, southwest Turkey(Wiley-Blackwell, 2013-11) Karabacak, Volkan; Yönlü, Önder; Dökü, Feyzullah Eray; Güneç Kıyak, Nafiye; Altunel, Erhan; Özüdoǧru, Şükrü; Yalçıner, Cahit Çağlar; Akyüz, Hüsnü SerdarThe ancient city of Kibyra in southwest Turkey has the potential to reveal the location and date of historical earthquakes. The most compelling evidence for earthquake faulting is observed in the city's Roman stadium. Damage related to seismic shaking is characterized by systematically collapsed columns, dilated and collapsed walls, and by rotated and displaced blocks in the stadium. Detailed archaeoseismological observations suggest that Kibyra was affected by earthquakes that were also recorded in historical earthquake catalogs. Although there is no historical record of a large earthquake after the 5th century A.D., Optically stimulated luminescence (OSL) dating of deposits under the collapsed blocks suggests a later seismic event. OSL results indicate that another large event occurred in southwest Turkey, probably around the 10-11th century A.D., and caused extensive damage (I-o = VIII-IX) to the Kibyra stadium.Yayın Quaternary rock uplift rates and their implications for the western flank of the North Anatolian Fault restraining bend; inferences from fluvial terrace ages(Blackwell Publishing Ltd, 2020-10-01) McClain, Kevin P.; Yıldırım, Cengiz; Ciner, Attila; Şahin, Sefa; Sarıkaya, Mehmet Akif; Özcan, Orkan; Güneç Kıyak, Nafiye; Öztürk, TuğbaIn the western flank of the North Anatolian Fault restraining bend (i.e., Central Pontides), the Filyos River incises through the uplifting Karabük Range, creating the ~1.7-km-deep Filyos River Gorge on the hanging wall of the reverse Karabük Fault. Seven fluvial strath terrace levels are preserved in this gorge. optically stimulated luminescence ages from quartz-rich sediments of five terrace levels reveal an average long-term rock uplift rate of 0.45 ± 0.02 mm yr?1 with an unsteady pattern of uplift during the last 542 ± 24 kyr. Uplift rates of 1.52 ± 0.6 and 0.74 ± 0.3 mm yr?1 occurred before 366 ± 19 kyr, followed by lower rates of ~0.1 and 0.31 mm yr?1 through present. These later uplift rates may reflect relatively slower tectonic rates since ~366 kyr, with closer similarity to regional uplift rates of ~0.3 mm yr?1 yielded from the eastern flank of the Central Pontides. The Karabük Range fluvial terraces are near the North Anatolian Fault, meaning pre- ~366 kyr uplift rates may be a glimpse of the highest Central Pontides Quaternary rock uplift rates on uplifting hanging wall blocks activated by the restraining bend. When we consider offshore seismic reflection data, the focal mechanism solution of the Bartın Earthquake, onshore structural data, and regional tectonic geomorphology, the western flank of the Central Anatolian Plateau's northern margin is propagating northward as a growing orogenic wedge with a positive flower-structure geometry.Yayın Behaviour of steel cushions subjected to combined actions(Springer, 2018-02) Yüksel, Ercan; Özkaynak, Hasan; Khajehdehi, Arastoo; Güllü, Ahmet; Smyrou, Eleni; Bal, İhsan Engin; Karadoğan, Hüseyin FarukMild steel is relatively low-cost and easily accessible material to fabricate some structural members. It would be a significant advantage if seismic energy dissipaters that are used in structures constructed in the earthquake prone areas, could also be produced on site. In this paper, a promising seismic energy dissipater made of mild steel, so-called steel cushion (SC) is presented. It is provided experimental and analytical responses of SCs subjected to bi-axial loadings. SC rolls under the lateral loading that allows relocation of the plasticized cross-section. Henceforth, SC dissipates considerable amount of seismic energy. A series of tests were performed to achieve experimentally the behavior of SC subjected to longitudinal and transversal loading. Finite Element Models (FEMs) were also generated to reproduce the experimental backbone curves and to predict the bi-directional response properties for discrete transversal forces and plate thicknesses. Closed-form equations were derived to determine yield and ultimate forces and the corresponding displacements as well as location of the plasticized sections. The behavior of SC could either be projected by the FEMs with the exhibited parameters or by means of the proposed closed-form equations and the normalized design chart.Yayın Disaster damage assessment for buildings using self-similarity descriptor(Institute of Electrical and Electronics Engineers Inc, 2015) Kahraman, Fatih; İmamoğlu, Mümin; Ateş, Hasan FehmiAssessment of damage caused by an earthquake is significant for coordinating emergency response teams and planning emergency aid. In this study, a robust method is proposed for detecting damaged buildings using pre- and post-event satellite images and building footprints. The method uses local self-similarity descriptor for change detection in buildings, which is shown to be robust against variations in illumination and small local deformations. The use of building footprints helps reduce the false alarms due to changes in non-building areas. The 2010 Haiti earthquake is analyzed with the suggested method and 72% true positive rate and 29% false positive rate are obtained for detection of collapsed buildings with respect to the ground truth data of UNITAR/UNOSAT.
