Browsing by Author "Aras, M"

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    Impact behavior of low strength concrete slab strengthened with fan type anchored carbon fiber-reinforced polymer strips
    Çaliskan, Ö; Aras, M; Yilmaz, T; Anil, Ö; Erdem, RT
    This study investigated the behavior of slabs produced with low compressive strength concrete without reinforcements under the effect of sudden dynamic impact loading. In addition, an experimental study was conducted by proposing a strengthening method with anchored carbon fiber-reinforced polymer (CFRP) strips to strengthen the nonreinforced slabs with low-strength concrete against sudden dynamic impact loads to improve their performance. The variables examined in the experimental study were the placement of the CFRP strips adhered to the concrete slabs for strengthening purposes and anchors in the strips. A constant energy level of impact loading was applied to the concrete slab test specimens with the authors' free weight drop test setup. The acceleration-time, displacement-time, strain-time, and applied impact loading-time measurements on the concrete slabs were examined, and comments were made about the strengthening method applied to the slab test specimens. In addition, numerical analysis of the tested concrete slabs with ABAQUS finite element software was performed, and the results were compared with the experimental results. In the comparison, it was investigated to what extent numerical analysis and this type of impact analysis can be done realistically and compatible with the experimental results. Within the scope of the study, the strengthening method applied with fan- type anchored CFRP strips significantly improved and increased the impact performance of concrete slabs produced with low-strength concrete.
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    Investigation of impact behavior of reinforced concrete beam to column connection strengthened with carbon fiber-reinforced polymer strips
    Kaya, T; Aras, M; Yilmaz, T; Çaliskan, Ö; Anil, Ö; Erdem, RT
    Reinforced concrete (RC) members may expose to impulsive dynamic loads due to the reasons such as the explosions occurring in the interior or exterior part of them, rockfall, the vehicle crash to the bridges, the collision of masses with the effects of floods and landslide. Many studies have investigated the effects of impulsive dynamic loads on the beam, column, and slab RC structural elements have been investigated in the literature. However, the authors have not encountered any study focused on the impact behavior of beam to column connections of the frames constructing the bearing system of reinforced concrete structures. Therefore, an experimental study has been planned to investigate RC beam impact behavior to column connections strengthened with carbon fiber-reinforced polymer (CFRP) strips. The concrete compressive strength, shear reinforcement spacing, CFRP strip spacing, and input impact energy applied to test specimens were taken as experimental variables. The time histories of impact load acting on test specimens, accelerations, displacements, and the strains measured from CFRP strips have been recorded in experiments. The experimental variables' effect on dynamic responses of RC beam to column connections strengthened with CFRP strips subjected to impact load has been interpreted in detail. The study's scope and improved numerical analysis procedure have also been introduced to verify experimental results. Good agreement between numerical and experimental results demonstrated that the presented numerical procedures could be safely used for evaluation of impact behavior of RC beam to column connections strengthened with CFRP strips.
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    Investigation of the role of stray cats for transmission of toxoplasmosis to humans and animals living in Izmir, Turkey
    Karakavuk, M; Can, H; Selim, N; Yesilsiraz, B; Atli, E; Sahar, EA; Demir, F; Gül, A; Özdemir, HG; Alan, N; Yalçin, M; Özkurt, O; Aras, M; Çelik, T; Can, S; Döskaya, AD; Gürüz, AY; Döskaya, M
    Introduction: Toxoplasma gondii is a protozoan parasite that has a widespread distribution among mammalians and birds. One of the reasons for the high prevalence may be due to ingesting oocyst disseminated by stray cats' feces. In Turkey, most of the citizens are closely associated with stray cats and they love to pet and feed them on the streets. In this study, we aimed to determine the prevalence of T. gondii DNA in feces of stray cats living in Izmir, Turkey in order to identify the transmission potential to humans and other animals. Methodology: Feces and blood samples of 465 stray cats were investigated for the presence of T. gondii oocysts by microscopy and for the presence of T. gondii DNA by two real time PCR methods. Furthermore, serum samples were analyzed for anti-T. gondii IgG antibodies using an ELISA. Results: Oocysts were detected in 0.43% of the stray cats by microscopy. T. gondii DNA was detected in 14.37% of the stray cats' feces samples. The seroprevalence rate was 37.84%. In the feces and/or blood PCR positive group, 35.89% of them were seropositive. Among the 176 seropositive cats, T. gondii DNA was detected in feces of 27 cats (15.34%). Conclusions: This study first time showed the inter relation of T. gondii DNA in feces and blood samples and seropositivity. In sum, over 14% of the stray cats living outdoor may have an important role in transmission of toxoplasmosis to humans in Izmir as well as to other animals.
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    Experimental investigation of impact behaviour of shear deficient RC beam to column connection
    Aras, M; Yilmaz, T; Çaliskan, Ö; Anil, Ö; Erdem, RT; Kaya, T
    Reinforced concrete (RC) structures may be subjected to sudden dynamic impact loads such as explosions occurring for different reasons, the collision of masses driven by rockfall, flood, landslide, and avalanche effect structural members, the crash of vehicles to the highway and seaway structures. Many analytical, numerical, and experimental studies focused on the behavior of RC structural elements such as columns, beams, and slabs under sudden dynamic impact loads. However, there is no comprehensive study on the behavior of the RC column-beam connections under the effect of sudden dynamic impact loads. For this purpose, an experimental study was performed to investigate the behavior of RC column-beam connections under the effect of low-velocity impact loads. Sixteen RC beam-column connections with a scale of 1/3 were manufactured and tested under impact load using the drop-weight test setup. The concrete compressive strength, shear reinforcement spacing in the beam, and input impact energy applied to test specimens were taken as experimental variables. The time histories of impact load acting on test specimens, accelerations, and displacements measured from the test specimens were recorded in experiments. Besides, shear and bending crack widths were measured. The effect of experimental variables on the impact behavior of RC beam-column connections has been determined and interpreted in detail. Besides, a finite element model has been established for verification and comparison of the experimental results by using ABAQUS software. It has been demonstrated that concrete strength, shear reinforcement ratio, and impact energy significantly affect the impact behavior of RC column-beam connections.