Yazar "Mansour, Walid" seçeneğine göre listele

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    Application of Ultra-High-Performance Concrete in Bridge Engineering: Current Status, Limitations, Challenges, and Future Prospects
    (Mdpi, 2023) Abdal, S.; Mansour, Walid; Agwa, Ibrahim; Nasr, Mohammed; Abadel, Aref; Ozkilic, Yasin Onuralp; Akeed, Mahmoud H.
    Ultra-high-performance concrete (UHPC) is a form of cementitious composite that has been the most innovative product in concrete technology over the last three decades. Ultra-high-performance concrete has been broadly employed for the design of numerous forms of construction owing to its excellent mechanical characteristics and durability, and studies on its behavior have grown fast in the last decades. While the utilization of ultra-high-performance concrete in bridge engineering (BE) is limited owing to its high costs, little is recognized about the utilization of UHPC in various BE elements. As a result of these issues, a comprehensive review of the current UHPC development trends should be conducted to determine its present state and perspective. This study presents a review of the state-of-the-art UHPC applications in BE. This review also discusses the current status, limitations, challenges, and areas for the further investigation of UHPC in BE. The aim of this research to help various construction stakeholders understand the distinctive characteristics, benefits, and barriers to the broad utilization of ultra-high-performance concrete applications. The understanding of UHPC will aid in increasing its entire market share in both the national and worldwide building sectors.
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    Buckling performance of pultruded glass fiber reinforced polymer profiles infilled with waste steel fiber reinforced concrete under axial compression
    (Techno-Press, 2022) Madenci, Emrah; Fayed, Sabry; Mansour, Walid; Ozkilic, Yasin Onuralp
    This study reports the results of a series of tests of pultruded glass fiber reinforced polymer (P--GFRP) box section composite profile columns, geometrically similar with/without concrete core, containing 0-1-2-3% steel fiber, with different lengths. The recycled steel wires were obtained from waste tyres. The effects of steel fiber ratio on the collapse and size effect of concrete filled P-GFRP columns under axial pressure were investigated experimentally and analytically. A total of 36 columns were tested under compression. The presence of pultruded profile and steel wire ratio were selected as the primary variable. The capacity of pultruded profiles with infilled concrete are averagely 9.3 times higher than the capacity of concrete without pultruded profile. The capacity of pultruded profiles with infilled concrete are averagely 34% higher than that of the pultruded profiles without infilled concrete. The effects of steel wire ratio are more pronounced in slender columns which exhibit buckling behavior. Moreover, the proposed analytical approach to calculate the capacity of P-GFRP columns successfully predicted the experimental findings in terms of both pure axial and buckling capacity.
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    Buckling performance of pultruded glass fiber reinforced polymer profiles infilled with waste steel fiber reinforced concrete under axial compression
    (Techno-Press, 2022) Madenci, Emrah; Fayed, Sabry; Mansour, Walid; Ozkilic, Yasin Onuralp
    This study reports the results of a series of tests of pultruded glass fiber reinforced polymer (P--GFRP) box section composite profile columns, geometrically similar with/without concrete core, containing 0-1-2-3% steel fiber, with different lengths. The recycled steel wires were obtained from waste tyres. The effects of steel fiber ratio on the collapse and size effect of concrete filled P-GFRP columns under axial pressure were investigated experimentally and analytically. A total of 36 columns were tested under compression. The presence of pultruded profile and steel wire ratio were selected as the primary variable. The capacity of pultruded profiles with infilled concrete are averagely 9.3 times higher than the capacity of concrete without pultruded profile. The capacity of pultruded profiles with infilled concrete are averagely 34% higher than that of the pultruded profiles without infilled concrete. The effects of steel wire ratio are more pronounced in slender columns which exhibit buckling behavior. Moreover, the proposed analytical approach to calculate the capacity of P-GFRP columns successfully predicted the experimental findings in terms of both pure axial and buckling capacity.
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    Experimental study on using recycled polyethylene terephthalate and steel fibers for improving behavior of RC columns
    (Elsevier, 2023) Fayed, Sabry; Madenci, Emrah; Bahrami, Alireza; Ozkilic, Yasin Onuralp; Mansour, Walid
    In this research, the behavior of RC columns reinforced with recycled polyethylene terephthalate (PET) fibers and steel fibers (SFs) was experimentally investigated. The experimental work included testing of 8 columns with the dimensions of 150 x 150 x 1000 mm subjected to the axial loading up to failure. Three volume fractions (1%, 2%, and 3%) were considered for both PET fibers and SFs. The axial/lateral displacements of the columns and the transverse/vertical strains versus the loads of the bars were recorded. The peak load, yield load, failure mode, ductility, and stiffness of the columns were studied in detail. The effects of plastic fibers (PFs) and SFs on the concrete characteristics were experimentally examined. Using 2% SFs in the mix increased the compressive strength, tensile strength, and toughness of concrete by 12.7%, 87.6%, and 304.8%, respectively. Furthermore, enhancement rates of the ultimate load capacity, stiffness, and ductility of the columns with 2% SFs were 15.6%, 72.6%, and 34.29%, respectively. The ultimate load capacity, initial stiffness, and ductility of the columns reinforced with 1% PF fiber were 9.43%, 62.6%, and 19.4%, respectively, greater than those of the columns without fibers. The columns' capacity was decreased with increasing SFs and PFs over 2%. An equation from ACI was used to predict the columns' capacity and the results agreed well with the experimental results.
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    Improving bond performance of ribbed steel bars embedded in recycled aggregate concrete using steel mesh fabric confinement
    (Elsevier Sci Ltd, 2023) Fayed, Sabry; Madenci, Emrah; Ozkilic, Yasin Onuralp; Mansour, Walid
    To investigate the bond behaviour of passively confined-recycled aggregate concrete (RAC), centre pull out tests were carried out on deformed steel bar with a diameter (O) of 12 mm. The recycled concrete aggregate (RCA) replacement ratios are 0, 30, 50, and 100 %. To investigate local bond strength, a short anchorage bonded length (La) of 10 was chosen. Steel mesh fabric (SMF) cylinders were used to confine the RAC around the bonded length of the bar. SMFs have diameters of 4O and 6O. SMF cylinder reinforcement ratios were estimated to be 0, 2.33, 3.04, 3.5, and 4.56 %. To accurately estimate maximal rising ratios in bond strength response owing to RAC confinement using SMFs, all specimens are intended to fail in the pull out mode (rather than the splitting mode). Unconfined and confined pull out specimens were tested for failure mechanism, ultimate local bond strength, bond stress-slip response, and ductility. When compared to similar unconfined specimens, confinement utilising SMFs dramatically improved bond stress-slip behaviour for all specimens including RCA. Ultimate bond strengths of RAC-unconfined specimens were 3.7-24.5 % lower than those of NAC-unconfined specimens, whereas ulti-mate slips of RAC-unconfined specimens were 25-140 % higher than those of NAC-unconfined specimens. Due to the usage of SMF cylinders at various levels of RCA, the ultimate bond strength of all confined specimens was dramatically increased when compared to unconfined specimens. When compared to a control unconfined NAC-specimen, the ductility of unconfined specimens containing 30 %, 50 %, and 100 % RCA decreased by 5.7, 18.6, and 39.6 %, respectively. In comparison, when compared to similar unconfined specimens, the maximum rising ratios in the ductility of confined specimens containing 0 % RCA, 30 % RCA, 50 % RCA, and 100 % RCA are 44.2 %, 77.9 %, 52.4, and 117.7 %, respectively. A novel proposed formula is developed to compute the ultimate bond strength of RAC while taking into account the influence of concrete grade, RCA content, concrete confinement via SMF, and transverse ties, and its results agree with the experimental results.