Browsing by Author "Umiye, Osman Ahmed"

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Citation - WoS: 1
Citation - Scopus: 1
Bending Performance of Reinforced Concrete Beams With Partial Waste Glass Aggregate Replacement Assessed by Experimental, Theoretical and Digital Image Correlation Analyses
(Nature Portfolio, 2025) Ozkilic, Yasin Onuralp; Basaran, Bogachan; Aksoylu, Ceyhun; Karalar, Memduh; Zeybek, Ozer; Althaqafi, Essam; Umiye, Osman Ahmed
This study examines the usage of waste glass aggregate (WGA) for the consumption of sustainable reinforced concrete regarding the replacement of fine aggregate (FA) and coarse aggregate (CA). For this purpose, a series of tests consisting of a total of 12 beams were carried out to explore the bending performance. The quantity of the longitudinal reinforcement section area and WGA percentage were selected as the prime variables. For this purpose, the aggregate was swapped with WGA with weight percentages of 10% and 20% for the FA and 10% and 20% for coarse aggregate. The test outcomes revealed that the crack and bending properties of the reinforced concrete beams (RCBs) were greatly affected by the section area of tension reinforcement and the percentage of the WGA. The WGA percentage might be effectively used as 20% of the partial replacement of FA. With the addition of FA to the mixture, the load-bearing capacity of RCB increases. The increase in the WGA percentage by more than 10% might cause a considerable reduction in the capacity of the RCBs, especially when the longitudinal reinforcement ratio is high. Furthermore, the digital image correlation method was used to show the cracks/micro-cracks and to define displacement in RCBs.
Citation - WoS: 13
Citation - Scopus: 15
Effect of Gbfs Ratio and Recycled Steel Tire Wire on the Mechanical and Microstructural Properties of Geopolymer Concrete Under Ambient and Oven Curing Conditions
(Elsevier, 2024) Celik, Ali Ihsan; Karalar, Memduh; Aksoylu, Ceyhun; Mydin, Md Azree Othuman; Althaqafi, Essam; Yilmaz, Fatih; Umiye, Osman Ahmed
In this study, the effects of waste steel wire ratios, granulated blast furnace slag (GBFS) ratios, and different curing methods on geopolymer concrete (GPC) were investigated. For this purpose, 12 mixtures were produced and eight of them were cured under ambient conditions and the remaining four were cured in an oven. Steel wire ratios and GBFS ratios were added to GPC as 0-1-2-3 % and 0-10-20 % by volume and weight, respectively. As a result of the mixtures, cubes, cylinders, and beams were obtained and these elements were subjected to compression, tensile, and flexural tests. As a result of the tests, the compressive strengths of the specimens were obtained as 8.5%, 19.7%, and 24.9% for ambient curing and 10.4%, 23.2%, and 32.2% for oven curing, respectively, as the steel wire fiber increased from 0 % to 3 %. The maximum compressive strength of the oven-cured specimen with 3% steel wire fiber was measured as 42.56 MPa. The tensile strength of GPC also increased as the steel wire increased. The highest tensile strength was obtained with 3 % steel wire. In addition, oven curing conditions increased the tensile strength more than ambient curing. The flexural strength (FS) increased by 21.3 %, 29.4%, and 33.8 % with increasing steel wire ratios of 1 %, 2 %, and 3 %, respectively. The FS was further increased by oven curing conditions and the maximum FS was achieved with 3 % steel wire. In ambient curing conditions, a successful geopolymerization was achieved due to the high calcium content in the samples containing 20 % GBFS. This allowed to obtain similar strengths between ambient curing and oven curing. Although the oven curing values were higher, similar results were obtained for the samples cured in an ambient containing 20 % GBFS. As a result of the study, mixtures containing 3 % steel wire and 20% GBFS provided sufficient strength without oven curing and increased the usability of GPC under ambient conditions.
Effect of Stirrup Spacing and Recycled Steel Wires on the Shear and Energy Dissipation of Pultruded GFRP Hybrid Beams
(Sage Publications Ltd, 2025) Ozkilic, Yasin Onuralp; Kalkan, Ilker; Aksoylu, Ceyhun; Madenci, Emrah; Umiye, Osman Ahmed; Althaqafi, Essam; Beskopylny, Alexey N.
The contribution of Recycled Steel Wires (RSW) to the shear strength and behavior of pultruded glass fiber reinforced polymer (P-GFRP) hybrid composite beams with reinforced concrete infill, denoted as P-GFRP beams, was investigated experimentally and analytically in the current study. A total of six specimens with varying RSW ratio and stirrup spacing of the reinforced concrete (RC) core and a fixed shear span-to-beam depth ratio were tested to failure. The addition of RSW to concrete was established to have greater contribution to the beam strength with increasing stirrup spacing, that is, decreasing transverse reinforcement ratio. The contribution of RSW to energy dissipation capacity was found to be more pronounced in the elastic range of beam response as compared to the inelastic range. The theoretical calculations indicated that the RC core prevented the P-GFRP encasement from complete failure due to shear-induced material rupture at the initial stages of loading. By maintaining their integrity, the reinforced concrete-filled box beams (RCFB) were able to resist loading until complete failure associated with flexure-induced material rupture and web compression buckling. A strut-and-tie model providing accurate strength estimates for P-GFRP beams was also proposed.
Citation - WoS: 3
Citation - Scopus: 3
Shear and Flexural Performance of Reinforced Geopolymer Concrete Beams Cured Under Ambient and Oven Conditions With Environmentally Friendly Waste Steel Tire Wire Additives
(Nature Portfolio, 2025) Ozkilic, Yasin Onuralp; Celik, Ali Ihsan; Aksoylu, Ceyhun; Karalar, Memduh; Mydin, Md Azree Othuman; Althaqafi, Essam; Umiye, Osman Ahmed
In this study, the effects of Granulated Blast Furnace Slag (GBFS) and Waste Steel Wire (WSW) admixtures on the flexural and shear performances of Reinforced Geopolymer Concrete Beams cured under oven and ambient conditions were investigated experimentally and analytically in detail. The research used 100 mm and 270 mm stirrup spacings and changed GBFS and WSW with 0%, 10%, 20%, and 1%, 2%, and 3%, respectively. To evaluate flexural and shear strength of reinforced GPC, 100 x 150 x 1000 mm samples were made. The results showed how material proportions affect flexural, and shear beam mechanical performance and ductility. In flexural beams, increasing the GBFS ratio to 10% enhanced load bearing capability and preserved ductility. However, 20% of GBFS reduced load bearing capability and brittle fractures. It was found that mixtures with GBFS of 10% and WSW of 3% are optimum for flexural beams. For shear beams, brittle fracture was observed for all GBFS and WSW ratios and ductile behavior was not achieved. Increasing GBFS content to 10% boosted capacity from 2.05 to 19.37%, however increasing it to 20% dropped capacity from 2.72 to 15.10%. Increasing WSW content enhanced load bearing capability, however increasing GBFS content over 10% did not. It is emphasized that different materials and design methods should be investigated to ensure ductile behavior in shear beams. Increasing the WSW ratio from 0 to 3% boosted energy consumption capacity by 2.78 times. But raising the GBFS ratio to 20% reduced energy consumption capacity by 66%. In addition, AS3600 predicted beam damage more correctly in different conventional computations. This study shows that the GBFS ratio should be limited to 10% and the WSW ratio to 3%. This combination maintains ductility in flexural beams and gives a safe design limit in shear beams while increasing load bearing capability. The results obtained provide important information that will shed light on new designs.