Makale Koleksiyonu
Article Colleciton
https://hdl.handle.net/11491/3677
2024-03-28T14:02:31Z
2024-03-28T14:02:31Z
Role of matrix structure and flaw size distribution modification on deflection hardening behavior of polyvinyl alcohol fiber reinforced engineered cementitious composites (PVA-ECC)
Tosun Felekoğlu, Kamile
Gödek, Eren
https://hdl.handle.net/11491/5680
2021-03-18T06:09:48Z
2019-01-01T00:00:00Z
Role of matrix structure and flaw size distribution modification on deflection hardening behavior of polyvinyl alcohol fiber reinforced engineered cementitious composites (PVA-ECC)
Tosun Felekoğlu, Kamile; Gödek, Eren
The multiple cracking and deflection hardening performance of polyvinyl alcohol fiber reinforced engineered cementitious composites (PVA-ECC) under four-point flexural loading have been investigated. Matrices with different binder combinations and W/B ratios (from 0.44 to 0.78) providing satisfactory PVA fiber dispersion were specially designed. Effect of pre-existing flaw size distribution modification on deflection hardening behavior was comparatively studied by adding 3 mm diameter polyethylene beads into the mixtures (6% by total volume). Natural flaw size distributions of composites without beads were determined by cross sectional analysis. The crack number and crack width distributions of specimens after flexural loading were characterized and the possible causes of changes in multiple cracking and deflection hardening behavior by flaw size distribution modification were discussed. Promising results from the view point of deflection hardening behavior were obtained from metakaolin incorporated and flaw size distribution modified PVA-ECCs prepared with W/B=0.53. The dual roles of W/B ratio and superplasticizer content on flaw size distribution, cracking potential and fiber-matrix bond behavior were evaluated. Flaw size distribution modification is found beneficial in terms of ductility improvement at an optimized W/B ratio.; 摘要:研究了聚乙烯醇纤维增强工程水泥基复合材料(PVA-ECC)在四点弯曲载荷作用下的多重开裂 和挠度硬化性能, 设计了不同粘结剂组合和水胶比(W/B)(0.44~0.78)的矩阵,使 PVA 纤维得到了较 好的分散。通过在混合物中加入直径为 3 mm 的聚乙烯微球(总体积为 6%),比较研究了预先存在的 缺陷尺寸分布修正对挠度硬化行为的影响。通过横断面分析,确定了无珠复合材料的自然缺陷尺寸分 布。对弯曲加载后试件的裂纹数和裂纹宽度分布进行了表征,并讨论了缺陷尺寸分布改性引起多次裂 纹和挠度硬化行为变化的可能原因。在 W/B=0.53 的条件下制备了含偏高岭土和缺陷尺寸分布改性的 PVA-ECC, 得到了较好的挠度硬化行为。分析了 W/B 比和超增塑剂含量对缺陷尺寸分布、潜在开裂、 和纤维-基体粘结行为的双重作用。在优化的 W/B 比下,发现了有利于改善延展性的尺寸分布修正。
2019-01-01T00:00:00Z
Çoklu çatlayan lifli kompozitlerin birim şekil değişiminin dijital görüntü korelasyonu ile analizi: Parametre etkilerinin değerlendirilmesi
Yıldırım, Tarık
Keskinateş, Muhammer
Gödek, Eren
Tosun Felekoğlu, Kamile
Felekoğlu, Burak
Önal, Okan
https://hdl.handle.net/11491/5662
2021-05-22T17:04:07Z
2020-01-01T00:00:00Z
Çoklu çatlayan lifli kompozitlerin birim şekil değişiminin dijital görüntü korelasyonu ile analizi: Parametre etkilerinin değerlendirilmesi
Yıldırım, Tarık; Keskinateş, Muhammer; Gödek, Eren; Tosun Felekoğlu, Kamile; Felekoğlu, Burak; Önal, Okan
Bu çalışmada çekme yüklemesi altında çoklu çatlak davranışı sergileyen lifli kompozitlerin birim şekil değiştirmeleri geleneksel deformasyon ölçer (LVDT) ve dijital görüntü korelasyonu (DIC) yöntemiyle incelenerek kıyaslanmıştır. DIC yönteminde ışık etkisi (kontrollü aydınlatma varlığı), görüntü çözünürlüğü, alt küme boyutu ve adım aralığı parametreleri ile iki farklı korelasyon yöntemi dikkate alınarak analizler gerçekleştirilmiştir. Uygun alt küme boyutunun seçilmesi ve görüntülerin kontrollü aydınlatma ile yüksek çözünürlük koşullarında alınması durumunda, DIC analizi sonucu elde edilen birim şekil değiştirme değerleri, LVDT’lerden elde edilen değerler ile örtüşmektedir.; In this study, strain of fiber reinforced composites exhibiting multiple cracking under tensile load was compared by using traditional deformation meter (LVDT-Linear Variable Differential Transformer) and digital image correlation (DIC) method. In the DIC method, analyzes were performed by taking the influence of light (presence of controlled illumination), image resolution, subset size and step size parameters and two different methods of correlation into account. If appropriate subset size is selected, the strain values obtained by DIC analysis corresponded to the values obtained from LVDTs when images are taken under controlled lighting and high resolution conditions.
2020-01-01T00:00:00Z
Behaviour of brick infill walls strengthened with expanded steel plates
Cumhur, Alper
Altundal, Adil
Kalkan, İlker
Aykaç, Sabahattin
https://hdl.handle.net/11491/2042
2021-10-30T20:46:25Z
2016-01-01T00:00:00Z
Behaviour of brick infill walls strengthened with expanded steel plates
Cumhur, Alper; Altundal, Adil; Kalkan, İlker; Aykaç, Sabahattin
The present study was dedicated to investigate an effective, economical and convenient method for strengthening brick infill walls, i.e. the use of externally-bonded expanded steel plates. A total of 30 plastered wall assemblies were tested under monotonic diagonal loading to investigate the contribution of these plates to the load capacities, ductilities and rigidities of brick walls. The plate thickness, bolt spacing and location of the plates in the wall were the parameters of the test program. The experiments indicated that application of the plates on the outermost fine plaster layer significantly improves the diagonal load–deflection behaviour of infill walls and reducing the bolt spacing provides the strengthened walls with higher load capacity values. An analytical expression was developed for estimating the diagonal load capacities of plated brick walls. The analytical load estimates were found to be in close agreement with the experimental values. © 2016, Springer Science+Business Media Dordrecht.
2016-01-01T00:00:00Z
Permeability characteristics of superfine cement-grouted sand
Avcı, Eyübhan
Mollamahmutoğlu, Murat
https://hdl.handle.net/11491/1965
2021-10-30T20:46:25Z
2017-01-01T00:00:00Z
Permeability characteristics of superfine cement-grouted sand
Avcı, Eyübhan; Mollamahmutoğlu, Murat
The aim of this research was to investigate the permeability of superfine cement-grouted sand. Initially, rheology of superfine cement suspensions was studied. The sedimentation and the setting time increased but the viscosity decreased as the water-cement ratio (w/c) increased. In addition, the penetrability of superfine cement suspensions with different w/c into various graded sand specimens prepared at different relative densities was tested. The penetrability of suspensions into the sand specimens was successful and increased as the w/c increased, but decreased as the relative density increased. Grouted sand samples were kept in a humidity room at a temperature of 20°C (68°F) until testing time and subjected to permeability tests at different time intervals. The coefficient of permeability increased as the w/c increased, but decreased as the relative density and the percentage of fines increased. Additionally, the coefficient of permeability of grouted samples decreased slightly with time. Copyright © 2017, American Concrete Institute. All rights reserved.
2017-01-01T00:00:00Z