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Now showing 1 - 10 of 22
  • Article
    Citation - WoS: 87
    Citation - Scopus: 106
    Effects of Cast-In Concrete Topping on Flexural Response of Precast Concrete Hollow-Core Slabs
    (Elsevier Sci Ltd, 2015) Baran, Eray
    Results of a study focusing on the flexural response of precast prestressed concrete hollow-core slabs with cast-in-place concrete topping are presented. The experimental part of the study included load testing of five precast concrete hollow-core units. The numerically determined flexural response of test specimens was later compared with the experimentally obtained behavior. Results demonstrate that a major composite action is valid between the hollow-core unit and the topping slab under load levels corresponding to uncracked state of the cross section. Existence of a topping slab resulted in improvements in the cracking moment and initial stiffness of hollow-core units. The beneficial effect of topping slab on the ultimate moment capacity was observed to be limited, mainly because of the loss of composite action prior to reaching the ultimate moment capacity. Horizontal shear strength at the interface between hollow-core unit and topping slab was determined (1) through limited number of pushoff load tests and (2) through calculations considering the load level corresponding to initiation of significant relative slip using the basic mechanics of materials approach and the simplified code expression. The measured and computed interface shear strength values were observed to be significantly lower than the horizontal shear strength values specified by the ACI and AASHTO Specifications. (C) 2015 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 20
    Flexural Strength Design Criteria for Concrete Beams Reinforced With High-Strength Steel Strands
    (Sage Publications inc, 2012) Baran, Eray; Arsava, Tugba
    This paper summarizes the result of a study investigating the flexural behavior of concrete beams reinforced with high-strength prestressing strands. Thirteen concrete beams reinforced with either conventional reinforcing bars or high-strength strands were fabricated and load tested in the experimental part of the study. No distinct difference was detected between the experimentally obtained cracking patterns of the two groups of beams. For the same reinforcement amount, beams reinforced with high-strength strands exhibited slightly smaller service stiffness than those reinforced with conventional reinforcing bars. A comparison of the measured and numerically predicted response of beam specimens indicated that the cracking load, peak load, and the deformation capacity of concrete beams can be accurately determined by a sectional analysis procedure for both types of reinforcement. The level of ductility present in concrete beams reinforced with high-strength strands is evaluated using the parameter called "displacement deformability ratio." Using the numerically determined maximum reinforcement limits for concrete beams reinforced with high-strength strands, an expression was proposed to be used at the design stage.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Experimental Determination of Resistance Characteristics of Support Details Used in Prestressed Concrete Bridge Girders
    (Asce-amer Soc Civil Engineers, 2009) Baran, Eray; Rohne, Ryan; French, Catherine E.; Schultz, Arturo E.
    Static load tests were performed on support details used at the ends of prestressed concrete pedestrian bridge girders to determine the resistance characteristics of girder supports in the direction perpendicular to the longitudinal axis of the girders. The specimens tested represent support details that have also been widely used in prestressed concrete highway bridges in Minnesota and in other states. Two specimens, one representing the free-end detail and one representing the restrained-end detail were subjected to a combination of vertical and lateral loads. The applied loading was intended to simulate the loading conditions to which the girder ends would be subjected in the event of an over-height vehicle collision with the bridge. The tests revealed two types of lateral load resisting mechanisms depending on the type of support detail. The specimen with the free-end detail resisted the lateral loading through sliding friction between the components of the support assembly. Deformation of this specimen was a combination of shear deformation of the bearing pad and sliding of various support components. The restrained-end detail exhibited larger lateral load capacity than the free-end detail due to the resistance provided by the anchor rods that were intended to prevent the lateral movement of the girder ends. Failure of the specimen with restrained-end detail was due to the concrete breakout and bending of the anchor rods.
  • Master Thesis
    Çelik Lifli Betonun Çekme ve Basınç Altındaki Davranışı
    (2015) Abdussalam, Alfadhıl. A. Gheıt. Alfadhıl; Mertol, Halit Cenan; Baran, Eray
    Çelik lifli beton, içinde belirli uzunluktaki çelik liflerin gelişigüzel ve düzgün bir şekilde yayılımı ile elde edilen bir beton karışımıdır. Liflerin kalitesi ve miktarı betonun mekanik özelliklerini etkilemektedir. Çelik liflerin betona katılması, betonun çekme tokluğunu ve sünekliğini arttırdığı, basınç dayanımını da ufak da olsa iyileştirdiği genel olarak kabul edilmiştir. Betonun kırılmasından sonra çekme gerilmelerinin lifler arasındaki dağılımı sağlandığından dolayı çelik liflerin yararı daha belirgin olarak görülmektedir. Bu araştırmanın amacı, çelik lifli betonun çekme ve basınç altındaki davranışının, konvansiyonel ve çelik lifli beton kullanılan çeşitli numuneler üzerinde uygulanan yükleme deneyleri ile incelenmesidir. Deney numuneleri basınç silindirlerinden (100×200 ve 150×300 mm), prizmatik eğilme dayanımı elemanlarından (150×150×600 mm) oluşmaktadır. Ayrıca çelik donatıyı çevreleyen prizmatik beton numuneler üzerinde çekme deneyleri gerçekleştirilmiştir. Çelik donatı çevresindeki prizmatik numuneler için gerçekleştirilen çekme deneylerinde beton prizmaların uzunlukları (500, 1000, ve 1500 mm) ve kesit boyutları (60×60, 100×100,150×150, 200×200 mm) değişkenler olarak uygulanmıştır. Yük-deformasyon davranışları elde edilmiş ve çelik lifli betonun basınç ve çekme altındaki gerilme-birim uzama ilişkileri bulunmuştur. Prizmatik eğilme numunelerinden elde edilen yük-deformasyon davranışları, bu araştırmada bulunan basınç ve çekme altındaki gerilme-birim uzama ilişkileri kullanılarak tahmin edilen yük deformasyon davranışları ile karşılaştırılmıştır. Ayrıca literatürde bulunan farklı gerilme-birim uzama modelleri kullanılarak davranışlar yeniden tahmin edilmiştir.
  • Master Thesis
    Farklı Katmanlarda Normal ve Çelik Lifli Beton Kullanılan Betonarme Kirişlerin Eğilme Davranışı
    (2015) Faeq, Mohammed Nozad Faeq; Mertol, Halit Cenan; Baran, Eray
    Bu çalışmada farklı katmanlarda normal ve çelik lifli beton kullanılan betonarme kirişlerin eğilme davranışı incelenmiştir. 180×250×3500 mm boyutlarındaki beşer numuneden oluşan iki grup şeklindeki kirişler dört nokta eğilme yüklemesi altında test edilmiştir. İki grup kirişte de 416 betonarme çeliği kullanılmıştır. Bu araştırmadaki ana değişken, kiriş numunelerinin yüksekliği boyunca bulunan katmanlarda kullanılan beton tipidir. Kiriş numunelerinin kesit yüksekliği 50'şer mm kalınlığında 5 katmana ayrılmıştır. 'F' grubu numunelerde, normal beton katmanlarından oluşan kirişlere, aşağıdan başlayarak, çelik lifli beton katmanlar eklenmiştir. 'P' grubu numunelerde ise çelik lifli beton katmanları kesit üst seviyesinden başlanarak eklenmiştir. Yükleme deneyleri sonucunda kiriş numunelerinin yük-deformasyon davranışları elde edilmiş ve bu davranışlar yük taşıma kapasitesi, servis rijitliği, kapasite sonrası eğim ve tokluk paratmeleri göz önüne alınarak değerlendirilmiştir. Kiriş numunlerinin yük-deformasyon davranışlarının, literatürde bulunan malzeme modelleri kullanılarak sayısal olarak belirlenmesi için analitik bir çalışma gerçekleştirilmiştir.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 28
    Damage in Reinforced-Concrete Buildings During the 2011 Van, Turkey, Earthquakes
    (Asce-amer Soc Civil Engineers, 2014) Baran, Eray; Mertol, Halit Cenan; Gunes, Burcu
    Two major earthquakes with magnitudes Mw=7.2 (ML=6.7) and ML=5.6 occurred in eastern Turkey on October 23 and November 19, 2011. The maximum measured peak ground accelerations for the two ground motions were 0.18g and 0.25g, respectively. The earthquakes resulted in various levels of damage to RC moment-resisting frame buildings ranging from minor cracking in brick partition walls to total collapse. This paper summarizes the field observations of the Atilim University Reconnaissance Team carried out in the region a few days after the two main shocks with an emphasis on the performance of RC buildings. A summary of the evolution of the Turkish seismic design code during the last 35 years is given, followed by an explanation of the behavior of RC buildings during the October 23 and November 9 earthquakes. The deformation types that were commonly observed in the heavily damaged or collapsed RC buildings include plastic hinging in columns attributable to stiffer beams, localization of damage in ground-story columns attributable to changes in the stiffness of the lateral load-resisting system caused by brick partition walls, and shear failure of columns caused by discontinuities in the partition walls adjacent to the columns. Poor concrete quality, inadequate development and lap splice length for reinforcement, and inadequate confinement in columns also contributed to the poor seismic behavior.
  • Article
    Citation - WoS: 100
    Citation - Scopus: 114
    Flexural Behavior of Lightly and Heavily Reinforced Steel Fiber Concrete Beams
    (Elsevier Sci Ltd, 2015) Mertol, Halit Cenan; Baran, Eray; Bello, Hussain Jibril
    Flexural behavior of lightly and heavily reinforced steel fiber concrete beams was investigated. The test series consisted of 20 singly reinforced beams having 180 x 250 x 3500 mm dimensions. The main parameters in the testing program were the type of concrete and the amount of longitudinal reinforcement. Ten different longitudinal reinforcement ratios (with a minimum of 0.2% and a maximum of 2.5%) covering the range from under-reinforced to over-reinforced beam behavior were used in the testing program. Two specimens were cast for each longitudinal reinforcement ratio, one specimen using conventional concrete (CC) and another specimen using steel fiber reinforced concrete (SFRC). Load-deflection behaviors were obtained and evaluated in terms of ultimate load, ultimate deflection, service stiffness, post-peak stiffness, and flexural toughness. The results indicate that the use of SFRC increases the ultimate load and service stiffness of the beams slightly compared to that of CC specimens. As reinforcement ratio increases, the ultimate deflection of SFRC specimens becomes significantly greater than that of CC specimens. For over-reinforced sections, the post-peak stiffness of the SFRC specimens is observed to be significantly lower than that of CC specimens. The flexural toughness of SFRC specimens is greater than that of CC specimens with the difference being significantly larger for over-reinforced sections. Experimental load-deflection relationships were also compared to the load-deflection curves obtained from sectional analyses based on strain compatibility and best fit stress-strain relationships for SFRC in tension and compression. (C) 2015 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 31
    Citation - Scopus: 37
    Behavior of Steel-Concrete Partially Composite Beams With Channel Type Shear Connectors
    (Elsevier Sci Ltd, 2014) Baran, Eray; Topkaya, Cem
    This paper summarizes the findings of an experimental study investigating the flexural behavior of partially composite beams incorporating channel type shear connectors. Results from monotonic load testing of four full-scale steel-concrete composite beams and a steel beam are presented. The main effort focused on identifying the variation of strength and stiffness properties of beams with various degrees of partial composite action. Behavior of channel shear connectors in the composite beam specimens is related to those previously obtained from push-out tests of similar connectors. Finally, recommendations of the related AISC Specification on the strength and stiffness of composite beams are used for the assessment of the influence of the degree of partial composite action on flexural behavior. The experimental results revealed that even for beams with relatively low degree of partial composite action, major improvement on moment capacity and stiffness was obtained as compared to the steel specimen. The measured moment capacity of both the partially composite and fully composite beams agreed acceptably with the calculated capacities. The effective moment of inertia and the lower bound moment of inertia as specified by the AISC Specification were observed to overestimate the measured flexural stiffness of beams for all degrees of partial composite action investigated. (C) 2014 Elsevier Ltd. All rights reserved.