Civil Engineering / İnşaat Mühendisliği
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Book Part Scherengestänge als elemente adaptiver morphologien(Birkhäuser, 2020) Akgün, Yenal; Maden, Feray; Gür, Şebnem; Kiper, Gökhan; Korkmaz, Koray; Aktaş, Engin; Yar Uncu, MüjdeZu allen Zeiten haben Menschen versucht, flexible Gebäude zu bauen, die sich ständig verändernden Anforderungen und Umweltbedingungen anpassen. Die Einbeziehung von Bewegung in die Architektur ist der Versuch, auf veränderliche Umstände mit neuen Lösungen zu reagieren. Das Konzept der Bewegung ist in der Tat nicht neu für die Architektur. Die Wurzeln gehen bis in die Antike zurück. Einfache, mit flexiblen Außenhäuten gebaute Nomadenzelte können als das erste Beispiel für adaptive Strukturen angesehen werden, die zum Schutz vor extremen Umweltbedingungen dienten.1 Die zum Abdecken des Daches im Colosseum von Rom verwendeten Leinwandbahnen sind ein weiteres Beispiel. Sie bildeten Markisen, die nicht nur Sonnenschutz boten, sondern für die Zuschauer durch ihr Durchhängen zur Mitte hin auch eine Brise einfingen.Article Citation - WoS: 3Citation - Scopus: 5Helenistik Kulelerde Yanal Yüke İlişkin Düzlem İçi ve Düzlem Dışı Duvar Davranışının Duvar Profilleri ve Açıklık Düzenlerine Bağlı Olarak İncelenmesi(Gazi Üniversitesi, 2020) Gençer, Funda; Turan, Mine; Aktaş, EnginDry masonry wall profiles constructed without using bonding material between blocks are encountered in different building types dated to Greek, Hellenistic and Roman periods. Depending on development of earthquake experiences, dry masonry wall profiles vary in terms of wall thickness, number of layers, relationship of layers and size, form, organization and relationship of blocks. In this study, the construction details increasing the structural strength in watch towers constructed in Hellenistic Period are aimed to be determined. This study is limited with investigation of effect of wall profiles and opening organizations on in-plane and out-of-plane wall behaviors under lateral loading. Primarily, wall profiles and opening types of dry masonry towers in ancient Caria, Pamphylia and Cilicia regions, that have not lost authenticity and integrity or had information about their authentic form, were documented. By using gathered data, hypothetic towers with different wall profiles and opening types are designed. To determine in-plane and out-of-plane wall behavior of hypothetic towers, simulation of quasi-static tilt analysis based on equilibrium were carried out, and form changes at walls and collapse angles of towers were identified. Wall profile and opening properties effecting on structural strength under lateral loading were determinedd.Article Citation - WoS: 1Citation - Scopus: 2Consolidation of a Bath Ruin in an Archaeological Site(Taylor and Francis Ltd., 2022) Durmuşlar, Feyza; Turan, Mine; Yücetürk, Kutay; Aktaş, EnginThe study has focused on consolidation of a historical bath ruin in an archaeological site. Cevher Pasa Bath, which is located in Tabae archaeological site in Denizli, Turkey and dated to the 15th century, presents structural problems. The aim of the study is to propose a framework for planning consolidation of the ruins of Cevher Pasa Bath so that conservation work regarding similar masonry ruins in archaeological sites can be guided. Thus, methods of architectural restoration and civil engineering are combined in an interdisciplinary scope. Provision of temporary shoring as an emergency intervention, consolidation and presentation of the ruin within the scope of an interdisciplinary restoration project, and monitoring of the asset within the frame of a monument management plan are suggested, respectively. Structural analysis considering stress and overturning moment checks are performed. Consolidation work includes only supporting of arch remains. Some walls of the ruin are weaker than other parts. These parts need further detailed analysis, and if necessary, further consolidation and strengthening are to be carried out. The monument management plan points out the necessity of collaboration of local and central administrations, and also non-governmental organisations.Article Citation - WoS: 1Citation - Scopus: 1Proposals for Monitoring Current Conservation Condition of Historical Masonry Buildings: Matrone Church and Çardak Han Cases;(Istanbul University Press, 2020) Durmuşlar,F.; Ipekci,E.; Turan,M.H.; Aktaş,E.The aim of this study is to transfer the international developments related to the process of diagnosis and monitoring of historical masonry structures to the national area. The method chosen is to test the recommendations made at the international level on national cases and to discuss the results obtained by comparing them. A review of preliminary studies, on-site observations, measured surveys, material characterizations, mapping and visual analysis have been carried out. An examination of structural characteristics and observed failures have also been detailed. Related risks have been evaluated with criteria developed by taking into consideration condition classes defined in the UNI EN 16096, titled Conservation of Cultural Property - Condition Survey and Report of Built Cultural Heritage. According to the defined risks and classes, priorities of interventions were determined. Two historical masonry buildings which possess characteristics of different periods and present different damage types were selected: Matrone Church in Ildiri, Çeşme, Izmir and Çardak Han in Çardak, Denizli. The condition reports of the selected buildings have been prepared. The critical points in the condition reporting of historical masonry buildings were determined: accurate comprehension of the authentic structural characteristics and related failures have priority in maintaining historical masonry structures. Identification of condition class and risk assessment of each historic masonry building should be made in accordance with a standard specific to the cases of our country, but in line with the European standards and current developments in the field of architectural restoration. Thus, it will be possible to evaluate the conservation state of our masonry assets in comparison with each other. The content and priority of interventions can be well planned with the participation of the necessary disciplines. © 2020 The authors.Article Poliamid 6/6 (pa 66) Mikrofiberler ile Toklaştırılmış Tabakalı Kompozitlerin Mod-ı Delaminasyon Direncinin İstatiksel Analizi(Niğde Ömer Halisdemir Üniversitesi, 2019) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, EnginFiber takviyeli kompozitler, ağırlıklarına oranla yüksek mukavemet ve rijitlikleri nedeniyle uzay ve otomotiv yapısal parçalarında yaygın olarak kullanılmaktadır. Delaminasyon, bu kompozitlerde görülen en yaygın ve kritik hasar modudur. Bu kompozitlerin delaminasyon direncini arttırmak amacıyla, nanokatkılar ile epoksi toklaştırması, dikişleme, z-pimler ve arayüzeyde mikro/nanofiber kullanılması gibi pek çok sayıda teknik geliştirilmiştir. Bu çalışmada, poliamid 6/6 (PA 66) mikrofiberler ile toklaştırılmış karbon fiber/epoksi kompozitlerin Mode-I delaminasyon direnci Weibull dağılımı kullanılarak istatiksel olarak analiz edilmiştir. Test verilerinin istatiksel olarak değerlendirilmesi sonucunda PA 66 mikrofiberlerin kullanılmasının %90 güven seviyesinde kırılma tokluğunu yaklaşık %445 mertebesinde arttırdığı gözlemlenmiştir.Article Citation - WoS: 3Citation - Scopus: 3Structural Vulnerability of Ancient Dry Masonry Towers Under Lateral Loading(Elsevier, 2020) Gençer, Funda; Hamamcıoğlu Turan, Mine; Turan, Mine; Aktaş, Engin; Aktaş, EnginUnderstanding how the original characteristics contribute to the structural behaviour of antique structures should be the initial stage of planning for conservation work. This study aims to identify the structural behaviour of dry masonry towers under lateral loadings, so that the decision-making process when determining their restoration can be adequately supported. Dry masonry towers in ancient Caria, Pamphylia, and Cilicia Regions are examined. Each of these three areas have very different seismic characteristics. A hypothetical testing process was designed by combining different characteristics from each of the towers. As a result, the characteristics affecting the structural resistance were determined as; the staggering ratio, the stone depth, the ratio between block length and height, the proportional relationship between height and length, the area, number and position of openings, and the distribution of header stones. These characteristics all interact together to determine the failure mechanism; so, understanding this interaction is critical when considering conservation. © 2020 Elsevier LtdArticle Citation - Scopus: 4Betonarme Çerçeve Yapıların Olasılıklı Sismik Analizi(Gazi Üniversitesi, 2006) Korkmaz, Armağan; Aktaş, EnginBetonarme çerçeve yapıların sismik davranışlarının belirlenmesinde, analizlere olasılıklı ifadelerin dahil edilmesi, sismik davranışın daha gerçekçi tanımlanmasına yardımıcı olacaktır. Çalışmada betonarme çerçeve yapıların olasılıklı sismik analizlerinin gerçekleştirilmesi amaçlanmış, bu amaçla örnek betonarme çerçeve yapılar ele alınmıştır. Bu betonarme çerçeve yapılar için öteleme analizleri DRAIN 2D programı ile yapılmıştır. Öteleme analizlerinin ardından zaman tanım alanında dinamik analizler gerçekleştirilmiştir. Öteleme analizleri, zaman tanım alanında dinamik analiz sonuçları ile karşılaştırılmıştır. Bu karşılaştırmanın ardından kırılganlık analizleri yapılmıştır. Betonarme çerçeve yapıların olasılıklı sismik davranışını ortaya koymak amacı ile kırılganlık analizleri ile kırılganlık eğrileri elde edilmiştir. Çalışmanın ana amacı, öteleme analizleri ile zaman tanım alanında dinamik analizlerin karşılaştırılması sonucu, daha gerçekçi bir sismik davranış tanımlama ihtiyacının olduğunu göstermek ve kırılganlık analizleri ile, sismik davranışın olasılıklı olarak daha gerçekçi bir şekilde ifadesini sağlayabilmektir.Conference Object Citation - WoS: 1Citation - Scopus: 2Structural Comparison of Scissor-Hinge Linkages(CRC Press, 2019) Maden, Feray; Akgün, Yenal; Yücetürk, Kutay; Aktaş, Engin; Yar Uncu, Müjde; Mitropoulou, C.Deployable structures can deploy from a compact to an expanded configuration by changing their sizes. The behaviors of these structures depend on some parameters such as geometric shape, member sizes and kinematic properties. To provide the deployment, not only the arrangements of structural members but also some restrictions must be considered. Moreover, contiguous members of the structures must let the large rotations to provide the transformation between different geometric forms from fully folded to fully deployed configurations. These requirements have an important impact on the fundamental properties of the structures related with structural performance, such as stiffness and strength. In this paper, stiffness of different scissor-hinge linkages are analyzed and compared. These linkages cover the same span with almost the same geometry and have the unit elements with same size and same weight. However, the geometry of unit elements is different from each other. The paper investigates the effect of this difference on the stiffness of whole system. © 2019 Taylor & Francis Group, London.Conference Object Citation - WoS: 2Citation - Scopus: 2A Case Study on the Selection of Optimum Loop Units for the Deployable Arch Structures Exposed To Lateral and Non-Uniform Gravity Loads(Elsevier, 2020) Yuceturk, K.; Aktas, E.; Maden, F.; Gur, S.; Mitropoulou, C. C.Radially deployable arches may be created by using various types of units. However, for any deployable structure to be constructed in real life, it should satisfy the structural regulations and codes. Despite various advantages from architectural perspective, deployable structures are weak to satisfy the operational code limits when compared to trusses with similar height and span. Therefore, weight minimization is very important to reduce the dead loads of the structure which facilitates the code-conformance of the structure. The optimization of the deployable structures requires an initial selection of the loop types to define the structure parametrically. An initial selection strategy depending on the loads on the structure is important to increase the efficiency of optimization process. Under uniform gravity loads, optimum arrangement for each unit type converges to a similar point. However, in the real world, the loads on the arches are not always uniform and the structure is exposed to nonuniform loadings such as point loads or lateral loads. This work focuses on the performance of various arches with different unit types under lateral and non-uniform vertical loads. Different lateral load and non-uniform gravity loading scenarios are created. For each scenario, the arches with different units are analyzed. In all cases, clear span and height are kept as same. The performance of an arch with a specific unit type for a given load is measured with a score that includes the deformations and the weight of the structure. All the members are assumed to be circular hollow sections with variable diameter and thickness to have a meaningful weight comparison between structures. This work intends to define an initial selection guide for deployable arches under typical non-uniform and lateral loading conditions. (C) 2020 The Authors. Published by Elsevier B.V.Article Citation - WoS: 40Citation - Scopus: 37Investigation of Interlayer Hybridization Effect on Burst Pressure Performance of Composite Overwrapped Pressure Vessels With Load-Sharing Metallic Liner(SAGE Publications, 2020) Kangal, Serkan; Kartav, Osman; Tanoğlu, Metin; Aktaş, Engin; Artem, Hatice SeçilIn this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [+/- 11 degrees/90 degrees(2)](3) to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic-plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.
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