İnşaat Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/395
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Article Citation - WoS: 3Citation - Scopus: 3Local Scour Evolution Around Semi-Circular End Bridge Abutment in Quasi-Unsteady Condition(Ice Publishing, 2022) Gokmener, Serkan; Gogus, MustafaIn this experimental study, the temporal development of local scour is studied around semi-circular end bridge abutments under quasi-unsteady clear-water flow conditions in a rectangular sediment channel. A step-wise hydrograph of 6 h duration is used in the experiments. Six different abutment lengths having constant width, with uniform sand as bed material, were tested for three different successive flows - each applied continuously for 2 h. Bathymetry of the bed level was measured around the abutment every 15 min with the help of a measurement device to observe temporal development of the local scour around the semi-circular end abutment. Effects of the abutment length, flow intensity and time on the scour depths around semi-circular end bridge abutments, along with those at the front, upstream and downstream faces of the abutment, are also investigated and discussed. It is shown that the maximum scour depth always occurs at the front noses of the abutments compared with those at the upstream and downstream noses. A dimensionless empirical formula is derived to predict the scour depth at the front nose of the abutment as a function of related parameters. The results reveal that flow intensity is the most critical parameter in scour development.Article Citation - WoS: 2Citation - Scopus: 3Effects of Collars on Local Scour Around Semi-Circular End Bridge Abutments(Emerald Group Publishing Ltd, 2023) Gogus, Mustafa; Daskin, Sueyla; Gokmener, SerkanThe occurrence of scour around bridge elements due to the transportation of bed material during flood events can cause serious structural damage and loss of life. Increased uncertainties in precipitation and runoff predictions due to climate change make this phenomenon more complex and dangerous. Bridge scour countermeasures should thus be more focused on decreasing scour formation around bridge elements. In this study, abutment scour under clear-water conditions with constant flow intensity was conducted and collars were tested as scour countermeasures around semi-circular end bridge abutments. The experimental study was performed in a rectangular channel with an almost uniform cohesionless bed material for 3 h with and without collars. Collars of various lengths located at different elevations around the abutments were tested to investigate the effect of collars on scour development. The results of the study showed that the scour depth decreased with increasing collar width and when the collar was placed below the bed level for a given abutment length. The results were compared with those of similar earlier studies to show the effect of abutment shape, size of the bed sediment and test durations on the development of scour depth around abutments.Article Citation - WoS: 1Citation - Scopus: 1Effect of Sediment Properties on Incipient Motion of Large Solitary Particles on Fixed Bed(Emerald Group Publishing Ltd, 2021) Gogus, Mustafa; Haspolat, EmreThe effect of sediment properties such as shape, size, specific weight and packing (support) condition on the incipient motion of large solitary particles was systematically investigated. A series of experiments was conducted in a rectangular tilting flume with a smooth fixed (rigid) bed under uniform flow conditions. In each experiment, a thin fibreglass rectangular rod of height 1/5 or 1.5/5 of the height of the particle was placed just downstream of the particle to imitate the interaction of particles in rivers. Contrary to common belief and knowledge, it was found that the Shields parameter decreased as the dimensionless grain diameter increased for a given bed slope under rough turbulent flow conditions. Moreover, a larger shear stress was needed to start the motion of particles on steeper slopes for a given particle diameter. An increase in the ratio of the support height to particle height by 50% resulted in an increase in the dimensionless critical shear stress by almost six times for the same particle and relative roughness.Article Citation - WoS: 17Citation - Scopus: 19Hydraulic Model Test Results of Baffle-Brush Fish Pass(Ice Publishing, 2015) Hassinger, Reinhard; Kucukali, SerhatThe flow characteristics (depth, velocity, energy dissipation) of a new baffle-brush fish pass were investigated experimentally in a 2 m wide rectangular flume which has a bed slope of 4% for discharges of 100-550 l/s. In all the experiments, quasi-uniform and sub-critical flow conditions and Froude numbers between 0.17 and 0.23 were observed. The Darcy-Weisbach friction factor was negatively correlated with the relative submergence of the brush elements. Two different characteristic velocity regions were identified, namely the baffle region and the brush region. The turbulence intensities were in the range 38-79% in the baffle zone and 13-31% in the brush zone. The hydraulic test results showed that this type of fish pass can produce adequate flow depth and favourable local flow velocities for the design discharge of 0.2 m(2)/s (relative submergence of brushes = 1.03), which is suitable for different fish species.Article Citation - WoS: 21Citation - Scopus: 28Flow and Turbulence Structure in a Baffle-Brush Fish Pass(Ice Publishing, 2018) Hassinger, Reinhard; Kucukali, SerhatThe flow an d turbulence characteristics of a new baffle-brush type fish pass were investigated experimentally in a 2 m wide rectangular flume with a bed slope of 4% and Reynolds and Froude numbers in the range 5 x 10(4)-2.8 x 10(5) and 0.17-0.23, respectively. The baffle-brush fishway combines the properties of a baffle (Larinier) fish pass with the features of the brush-furnished fishway. The baffle-brush fish pass ensures continuous low-and high-velocity migration corridors for both strong (e.g. salmon) and weak swimming (e.g. river lamprey) fish, with negligible flow accelerations (i.e. quasi-uniform conditions). The turbulent kinetic energy (TKE) takes its maximum value near the centre of the baffle zone and decays towards the brush zone. The effects of the Reynolds number (Re) on the resultant velocity and TKE distributions were also investigated. For Re = 2 x 10(5), the TKE was in the range 0.05-0.21 m(2)/s(2) with an average value of 0.11 m(2)/s(2) in the baffle section, whereas it ranged between 0.007 and 0.04 m(2)/s(2) with an average value of 0.02 m(2)/s(2) in the brush section. In the proposed fish pass there is no need to build resting pools.Article Citation - WoS: 6Citation - Scopus: 8An Experimental Investigation of Flow Resistance and Turbulent Flow in Brush Fish Pass(Ice Publishing, 2019) Kucukali, SerhatThe present study aimed to search for chicken abdominal fat deposition-related polymorphisms within RB1 and to provide functional evidence for significantly associated genetic variants. Association analyses showed that 11 single nucleotide polymorphisms (SNPs) in intron 17 of RB1, were significantly associated with both abdominal fat weight (P < 0.05) and abdominal fat percentage (P < 0.05). Functional analysis revealed that the A allele of g.32828A>G repressed the transcriptional efficiency of RB1 in vitro, through binding nuclear factor-kappa B (NF-B-K) and SRY-related HMG box protein 2 (SOX2). Furthermore, RB1 mRNA expression levels in the abdominal fat tissue of individuals with the A/A genotype of g.32828A>G were lower than those of individuals with the G/G genotype. Collectively, we propose that the intronic SNP g.32828A>G of RB1 is an obesity-associated variant that directly affects binding with NF-B-K and SOX2, leading to changes in RB1 expression which in turn may influence chicken abdominal fat deposition.