Yazar "Koroglu, Mehmet Alpaslan" seçeneğine göre listele

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    Artificial neural network for predicting the flexura bond strength of FRP bars in concrete
    (Walter De Gruyter Gmbh, 2019) Koroglu, Mehmet Alpaslan
    The bond strength between fibre-reinforced polymer (FRP) rebars and concrete is one of the most significant aspects of composite behaviour for rebars and concrete. In this study, a database of 408 beam type specimens consisting of beam end specimens, beam anchorage specimens and splice beam specimens was compiled from the current literature and used to develop a simple prediction using the artificial neural network (ANN). The data used for modelling were organised in a format of eight input parameters that include FRP type, cover bar surface, confinement, bar diameter (d(b)), concrete compressive strength (root f(c)), minimum cover-to-bar-diameter ratio (c/d(b)), bar-development-length-to-bar-diameter ratio (l/d(b)), and the ratio of the area of transverse reinforcement to the product of transverse reinforcement spacing, the number of developed bars and bar diameters (A(tr)/snd(b)). Additionally, a simple prediction formula by regression analysis was developed. The root mean square error and R-2 values of the testing data were found in order to compare the results of both ANN and the proposed model with existing regulations. The new ANN model predicts the bond strength of FRP bars in reinforced concrete with 0.8989 R-2, thus yielding better results when compared with existing regulations.
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    Artificial neural network for predicting the flexura bond strength of FRP bars in concrete
    (Walter De Gruyter Gmbh, 2019) Koroglu, Mehmet Alpaslan
    The bond strength between fibre-reinforced polymer (FRP) rebars and concrete is one of the most significant aspects of composite behaviour for rebars and concrete. In this study, a database of 408 beam type specimens consisting of beam end specimens, beam anchorage specimens and splice beam specimens was compiled from the current literature and used to develop a simple prediction using the artificial neural network (ANN). The data used for modelling were organised in a format of eight input parameters that include FRP type, cover bar surface, confinement, bar diameter (d(b)), concrete compressive strength (root f(c)), minimum cover-to-bar-diameter ratio (c/d(b)), bar-development-length-to-bar-diameter ratio (l/d(b)), and the ratio of the area of transverse reinforcement to the product of transverse reinforcement spacing, the number of developed bars and bar diameters (A(tr)/snd(b)). Additionally, a simple prediction formula by regression analysis was developed. The root mean square error and R-2 values of the testing data were found in order to compare the results of both ANN and the proposed model with existing regulations. The new ANN model predicts the bond strength of FRP bars in reinforced concrete with 0.8989 R-2, thus yielding better results when compared with existing regulations.
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    Behavior of composite self-compacting concrete (SCC) reinforced with steel wires from waste tires
    (Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2018) Koroglu, Mehmet Alpaslan
    Large amount of waste tires are generated progressively every year. Therefore, many researches have been conducted on using recycled tire products in several civil engineering products. This paper is focusing on feasibility of using recycled steel fibers from waste tires as reinforcement in functionally graded self-compacting concrete (SCC). Firstly, fresh and hardened properties of the normal and steel fiber reinforced concretes were investigated. After obtaining the mechanical properties of steel fiber reinforced SCC, 16 multi-layered beams were tested under 4 point bending test by considering various fiber fractions and layer thickness. Additionally, SEM images were used to maintain the failure mechanisms between steel fibers and concrete matrix.
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    Experimental Study on Beam-to-Column Connections of Steel Frame Structures with Steel Slit Dampers
    (Asce-Amer Soc Civil Engineers, 2015) Koken, Ali; Koroglu, Mehmet Alpaslan
    After the Northridge and Kobe earthquakes important experimental programs on beam-to-column connections were developed because of brittle fractures at welded beam-to-column connections. A number of studies are being carried out on a variety of materials and systems that dissipate the seismic loading effects in order to improve the seismic performance of steel frames. In the research reported in this paper, a slit steel damper system was developed to prevent the damage formation of standard columns and beams by dissipating lateral loads at the beam-to-column connections of steel frames. Therefore, the columns and beams of steel frames will not be damaged after a heavy earthquake, and the structures might be put into the service again simply by replacing the dampers at the connection sites. The seismic performance of the studied connection was verified through cyclic tests of two full-scale steel frames that had slit dampers and of one specimen that had a conventional extended end-plate connection. Test results indicated that the proposed connection showed a good hysteretic behavior, a good energy dissipation capacity, and good rigidity. However, plastic deformation is limited to the slit dampers, while the inelastic behavior of the beams and columns is prevented. (C) 2014 American Society of Civil Engineers.
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    Experimental study on compressive behavior and failure analysis of composite concrete confined by glass/epoxy ± 55° filament wound pipes
    (Elsevier Sci Ltd, 2018) Gemi, Lokman; Koroglu, Mehmet Alpaslan; Ashour, Ashraf
    This paper investigates the strength and ductility of concrete confined by Glass/Epoxy +/- 55 degrees Filament Wound Pipes (GFRP) under axial compression. A total of 24 cylindrical specimens were prepared with expansive and Portland cements, properly compacted and un-compacted for different composite fresh concrete matrix. Test results showed that compressive strength and axial deformation at failure of concrete confined with GFRP tubes increased by an average of 2.85 and 5.57 times these of unconfined concrete, respectively. Macro and micro analyses of GFRP pipes after failure were also investigated. Debonding, whitening, matrix/transfer cracking, delamination and splitting mechanisms were detected at failure, respectively. The experimental results were also employed to assess the reliability of design models available in the literature for confined concrete compressive strength.
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    Flexural performance of reinforced concrete beams strengthened with prestressed near-surface-mounted FRP reinforcements
    (Elsevier Sci Ltd, 2016) Kara, Ilker Fatih; Ashour, Ashraf F.; Koroglu, Mehmet Alpaslan
    A numerical method for estimating the curvature, deflection and moment capacity of reinforced concrete beams strengthened with prestressed near-surface-mounted (NSM) FRP bars/strips is presented. A sectional analysis is carried out to predict the moment curvature relationship from which beam deflections and moment capacity are then calculated. Based on the amount of FRP bars, different failure modes were identified, namely tensile rupture of prestressed FRP bars and concrete crushing before or after yielding of steel reinforcement. Comparisons between experimental results available in the literature and predicted curvature, moment capacity and deflection of reinforced concrete beams with prestressed NSM FRP reinforcements show good agreement. A parametric study concluded that higher prestressing levels improved the cracking and yielding loads, but decreased the beam ductility compared with beams strengthened with nonprestressed NSM FRP bars/strips. (C) 2016 Elsevier Ltd. All rights reserved.
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    Mechanical properties of self-compacting concrete with recycled bead wires
    (Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2019) Koroglu, Mehmet Alpaslan; Ashour, Ashraf
    This paper investigates the properties of self-compacting concrete with waste steel bead wires obtained as a result of the separation of waste tires. Waste steel bead wires were added to concrete between 1% and 5% by weight with an increment of 1%. In total, 54 cubes, 6 cylinders and 6 beams were cast, cured and tested in according to various standards to obtain the compressive, splitting tensile and flexural strengths, respectively. In addition, 6 cubes were left in salty water solution with a salt concentration of 4% for 120 days and tested in compression. A scanning electron microscopy (SEM) was also conducted on samples after failure. Test results showed that short time corrosion of steel fibers does not affect the mechanical properties. Also, the increase in the ratio of steel fiber was found to contribute positively to the mechanical properties of concrete up to 4%, beyond which, mechanical properties were reduced. Finally, in the samples subjected to bending tests, it has been found that a 6-fold increase in bending strength compared to the reference (non-fiber) sample was achieved in case of steel fiber ratio of 4% and 5%.
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    Tests of Continuous Concrete Slabs Reinforced with Basalt Fiber-Reinforced Plastic Bars
    (Amer Concrete Inst, 2017) Kara, Ilker Fatih; Koroglu, Mehmet Alpaslan; Ashour, Ashraf F.
    This paper presents experimental results of three continuously supported concrete slabs reinforced with basalt fiber-reinforced polymer (BFRP) bars. Three different BFRP reinforcement combinations of over and under reinforcement ratios were applied at the top and bottom layers of continuous concrete slabs tested. One additional concrete continuous slab reinforced with steel bars and two simply supported slabs reinforced with under and over BFRP reinforcements were also tested for comparison purposes. All slab sections tested had the same width and depth but different amounts of BFRP reinforcement. The experimental results were used to validate the existing design guidance for the predictions of moment and shear capacities, and deflections of continuous concrete elements reinforced with BFRP bars. The continuously supported BFRP reinforced concrete slabs illustrated wider cracks and larger deflections than the control steel-reinforced concrete slab. All continuous BFRP reinforced concrete slabs exhibited a combined shear-flexure failure mode. ACI 440.1R-15 equations give reasonable predictions for the deflections of continuous slabs (after first cracking) but stiffer behavior for the simply supported slabs, whereas CNR DT203 reasonably predicted the deflections of all BFRP slabs tested. On the other hand, ISIS-M03-07 provided the most accurate shear capacity prediction for continuously supported BFRP reinforced concrete slabs among the current shear design equations.
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    Tests of Continuous Concrete Slabs Reinforced with Basalt Fiber-Reinforced Plastic Bars
    (Amer Concrete Inst, 2017) Kara, Ilker Fatih; Koroglu, Mehmet Alpaslan; Ashour, Ashraf F.
    This paper presents experimental results of three continuously supported concrete slabs reinforced with basalt fiber-reinforced polymer (BFRP) bars. Three different BFRP reinforcement combinations of over and under reinforcement ratios were applied at the top and bottom layers of continuous concrete slabs tested. One additional concrete continuous slab reinforced with steel bars and two simply supported slabs reinforced with under and over BFRP reinforcements were also tested for comparison purposes. All slab sections tested had the same width and depth but different amounts of BFRP reinforcement. The experimental results were used to validate the existing design guidance for the predictions of moment and shear capacities, and deflections of continuous concrete elements reinforced with BFRP bars. The continuously supported BFRP reinforced concrete slabs illustrated wider cracks and larger deflections than the control steel-reinforced concrete slab. All continuous BFRP reinforced concrete slabs exhibited a combined shear-flexure failure mode. ACI 440.1R-15 equations give reasonable predictions for the deflections of continuous slabs (after first cracking) but stiffer behavior for the simply supported slabs, whereas CNR DT203 reasonably predicted the deflections of all BFRP slabs tested. On the other hand, ISIS-M03-07 provided the most accurate shear capacity prediction for continuously supported BFRP reinforced concrete slabs among the current shear design equations.