Yazar "Aksoylu, Ceyhun" seçeneğine göre listele

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    2007 ve 2019 Deprem Yönetmeliklerinde Betonarme Binalar İçin Yer Alan Farklı Deprem Kuvveti Hesaplama Yöntemlerinin Karşılaştırılmalı Olarak İrdelenmesi
    (Kırıkkale Üniversitesi, 2021) Aksoylu, Ceyhun; Arslan, Musa Hakan
    Bu çalışmada, 2019 yılında yürürlüğe giren Türkiye Bina Deprem Yönetmeliği (TBDY-2019) ile 2007 Türk Deprem Yönetmeliğinin (TDY-2007) deprem hesap yöntemleri açısından karşılaştırılmasına odaklanılmıştır. Bunun için aynı plan özelliklerine sahip 3-4-5 katlı çerçeve + perde türü betonarme binalar üzerinde ETABS programında lineer elastik analizler gerçekleştirilmiştir. Yapılan analizlerde deprem riski yüksek olan İstanbul / Kartal bölgesi dikkate alınmıştır. TBDY-2019 için zemin sınıfı ZA, deprem tasarım sınıfı 1 (DTS1), TDY-2007’de ise zemin sınıfı Z1, deprem bölgesi 1. derece olarak dikkate alınmıştır. Modellemeler sonucu binaların her iki yönü için Eşdeğer Deprem Yükü yöntemi (EDY) ve Mod Birleştirme yöntemi (MBY) kullanılarak karşılaştırmalar yapılmıştır. Ayrıca her bir yapı için taban kesme kuvvetleri, periyot ve göreli kat ötelenme değerleri de hesaplanmıştır. Binaların her iki yöndeki EDY’den elde edilen taban kesme kuvvetleri 3-4-5 katlı yapılar için x ve y yönü için sırasıyla %40-%43 ve %39-47 oranında TBDY-2019’dan daha az sonuç vermesiyle sonuçlanmıştır. MBY’de ise bu oran sırasıyla %38-%46 ve %35-45 şeklindedir. Bu durum TBDY-2019 yönetmeliğindeki çatlamış kesit rijitliğinin kullanılmasından dolayı kat deplasmanların ve sistem periyodunun artmasına, taban kesme kuvvetlerinin ise azalmasına yol açmasıyla açıklanabilir. Ayrıca karşılaştırmalı spektrum eğrilerinden TBDY-2019 spektrum eğrisinin TDY-2007’ye göre daha düşük ivme değerleri verdiği görülmüştür. Bununla beraber çatlamış kesite göre yapılan göreli kat ötelemesinin TBDY-2019’da daha katı olduğu görülmüştür.
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    Effect of the GFRP wrapping on the shear and bending Behavior of RC beams with GFRP encasement
    (Techno-Press, 2022) Ozkilic, Yasin Onuralp; Gemi, Lokman; Madenci, Emrah; Aksoylu, Ceyhun; Kalkan, Ilker
    The need for establishing the contribution of pultruded FRP encasements and additional FRP wraps around these encasements to the shear strength and load-deflection behavior of reinforced concrete beams is the main motivation of the present study. This paper primarily focuses on the effect of additional wrapping around the composite beam on the flexural and shear behavior of the pultruded GFRP (Glass Fiber Reinforced Polymer) beams infilled with reinforced concrete, taking into account different types of failure according to av/H ratio (arch action, shear-tension, shear-compression and pure bending). For this purpose, nine hybrid beams with variable shear span-to-depth ratio (av/H) were tested. Hybrid beams with 500 mm, 1000 mm, and 1500 mm lengths and cross-sections of 150x100 mm and 100x100 mm were tested under three-point and four-point loading. Based on the testing load-displacement relationship, ductility ratio, energy dissipation capacity of the beams were evaluated with comprehensive macro damage analysis on pultruded GFRP profile and GFRP wrapping. The GFRP wraps were established to have a major contribution to the composite beam ductility (90-125%) and strength (40-75%) in all ranges of beam behavior (shear-dominated or dominated by the coupling of shear and flexure). The composite beams with wraps were showns to reach ductilities and strength values of their counterparts with much greater beam depth.
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    Effects of the location and size of web openings on shear behavior of clamped-clamped reinforced concrete beams
    (Techno-Press, 2024) Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp; Hakeem, Ibrahim Y.; Kalkan, Ilker
    The present study pertains to the effects of variations in the location and size of drilled web openings on the behavior of fixed -fixed reinforced concrete (RC) beams. For this purpose, a reference bending beam with a transverse opening in each half span was tested to failure. Later, the same beam was modeled and analyzed with the help of finite element software using ABAQUS. Upon achieving close agreement between the experimental and numerical results, the location and size of the web opening were altered to uncover the effects of these factors on the shear strength and load -deflection behavior of RC beams. The experimental failure mode of the tested beam and the numerical results were also verified by theoretical calculations. In numerical analysis, when compared to the reference (D0) specimen, if the distance of the opening center from the support is 0 or h or 2h, reduction in load -bearing capacity of 1.5%-22.8% or 2.0%-11.3% or is 4.1%-40.7%. In other words, both the numerical analyses and theoretical calculations indicated that the beam behavior shifted from shear -controlled to flexure -controlled as the openings approached the supports. Furthermore, the deformation capacities, energy absorption values, and the ductilities of the beams with different opening diameters also increased with the decreasing distance of the opening from supports. Web compression failure was shown to be the predominant mode of failure of beams with large diameters due to the lack of sufficient material in the diagonal compression strut of the beam. The present study indicated that transverse openings with diameters, not exceeding about 1/3 of the entire beam depth, do not cause the premature shear failure of RC beams. Finally, shear damage should be prevented by placing special reinforcements in the areas where such gaps are opened.
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    Effects of Waste Powder, Fine and Coarse Marble Aggregates on Concrete Compressive Strength
    (Mdpi, 2022) Basaran, Bogachan; Kalkan, Ilker; Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp; Sabri, Mohanad Muayad Sabri
    The use of marble wastes in concrete mixtures, causing air and water pollution, has been promoted in the academic and practical spheres of the construction industry. Although the effects of various forms (powder, fine, coarse and mixed) of this waste on the concrete compressive strength has been subject to a decent number of studies in the literature, the difficulties in reaching specific conclusions on the effect of each test parameter constitute a major restraint for the proliferation of the use of marble wastes in the concrete industry. Most of these studies are far from underscoring all of the parameters affecting the concrete compressive strength. Due to the urgent need in the literature for comprehensive studies on concrete mixtures with marble wastes, the results of the axial compression tests on a total of 429 concrete mixtures with marble aggregates were compiled by paying special attention to reporting all test variables (form and content of marble wastes, water-cement ratio, cement content, proportion of coarse and fine aggregates in all aggregates) affecting the concrete strength. In this context, multivariate regression analyses were carried out on the existing test results. These regression analyses yielded to relationships between the change in concrete compressive strength and the test parameters for each and every form of marble waste (powder, fine and coarse aggregate). The study indicated that independent from the form of marble wastes (as powder, fine aggregate or coarse aggregate), aggregate replacements of up to 50% can yield to significant changes in the concrete compressive strength. In addition, the analytical estimates from the developed equations exhibited a high correlation (a least r value of 0.91) with the experimental results from the previous studies, yielding to rather low error values (RMSE value is 5.06 MPa at max). For this reason, the developed equations can consistently predict the changes in concrete compressive strength with varying amounts and forms of the marble aggregates as well as the other test variables.
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    Lateral torsional buckling of doubly-symmetric steel cellular I-Beams
    (Techno-Press, 2023) Ertenli, Mehmet Fethi; Erdal, Erdal; Buyukkaragoz, Alper; Kalkan, Ilker; Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp
    The absence of an important portion of the web plate in steel beams with multiple circular perforations, cellular beams, causes the web plate to undergo distortions prior to and during lateral torsional buckling (LTB). The conventional LTB equations in the codes and literature underestimate the buckling moments of cellular beams due to web distortions. The present study is an attempt to develop analytical methods for estimating the elastic buckling moments of cellular beams. The proposed methods rely on the reductions in the torsional and warping rigidities of the beams due to web distortions and the reductions in the weak-axis bending and torsional rigidities due to the presence of web openings. To test the accuracy of the analytical estimates from proposed solutions, a total of 114 finite element analyses were conducted for six different standard IPEO sections and varying unbraced lengths within the elastic limits. These analyses clearly indicated that the LTB solutions in the AISC 360-16 and AS4100:2020 codes overestimate the buckling loads of cellular beams within elastic limits, particularly at shorter span lengths. The LDB solutions in the literature and the Eurocode 3 LTB solution, on the other hand, provided conservative buckling moment estimates along the entire range of elastic buckling.
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    Shear and Bending Performances of Reinforced Concrete Beams with Different Sizes of Circular Openings
    (Mdpi, 2023) Ozkilic, Yasin Onuralp; Aksoylu, Ceyhun; Hakeem, Ibrahim Y.; Ozdoner, Nebi; Kalkan, Ilker; Karalar, Memduh; Stel'makh, Sergey A.
    The present study pertains to the effects of transverse opening diameters and shear reinforcement ratios on the shear and flexural behavior of RC beams with two web openings across different spans, i.e., a single opening in each half-span. Within the scope of the study, a total of 12 RC beams with five different opening diameter-to-beam depth ratios (0, 0.20, 0.27, 0.33, 0.40, and 0.47) and two shear reinforcement ratios were tested to failure under four-point bending. The load capacities, ductilities, rigidities and energy dissipation capacities in the elastic and plastic ranges of beam behavior were compared. Furthermore, the load capacities of the beams were compared to the existing analytical shear strength formulations in the literature. The test results indicated that whether an RC beam with openings has adequate or inadequate amounts of shear reinforcement, the frame-type shear failure becomes much more pronounced with increasing opening diameter. The reductions in the load capacity and modulus of toughness with increasing opening diameter are more considerable in the presence of inadequate amounts of shear reinforcement, while the beam ductility is less affected in shear-deficient RC beams with openings as compared to the ones with adequate shear reinforcement.
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    Use of waste steel fibers from CNC scraps in shear-deficient reinforced concrete beams
    (Techno-Press, 2023) Kalkan, Ilker; Ozkilic, Yasin Onuralp; Aksoylu, Ceyhun; Mydin, Md Azree Othuman; Martins, Carlos Humberto; Hakeem, Ibrahim Y.; Isik, Ercan
    The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to shear-dominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5-23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.