İnşaat Mühendisliği Bölümü

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Citation - WoS: 3
Citation - Scopus: 4
An analytical investigation of rigid plastic beams underimpact loading
(Gazi Univ, Fac Engineering Architecture, 2015) Gultop, Tekin; Gültop, Tekin; Yilmaz, Mahmut Cem; Alyavuz, Bahadir; 5168; İnşaat Mühendisliği
Beams might be subjected to impact loading which is a particular type of dynamic loading during their service lives. In this study the behaviour of beams under low speed impact loading has been investigated analytically. Simply supported and fixed ended beams have been analyzed with the assumption of rigid plastic behaviour. The collapse mechanism has been assumed to emerge by the instant formation of plastic hinges, hence, a limit analysis has been performed under dynamic loading considering the conservation principles of energy and momentum. The behaviour of rigid plastic beams under impact loading has been compared to the behaviour of elastic beams under similar loading conditions.
Citation - WoS: 5
Citation - Scopus: 5
An experimental investigation of flow resistance and turbulent flow in brush fish pass
(Ice Publishing, 2019) Kucukali, Serhat; Küçükali, Serhat; 20413; İnşaat Mühendisliği
The 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.
Citation - WoS: 8
Citation - Scopus: 8
Damage Limits for Ductile Reinforced Concrete Shear Walls
(Turkish Chamber Civil Engineers, 2012) Kazaz, Ilker; Gulkan, Polat; 5743
Although the strain based damage limits proposed in the existing Turkish Earthquake Code were adopted from reported studies of leading researchers, the appropriateness of these limit state definitions and corresponding values to evaluate the performance with the analytical tools and methods used in the displacement based design and assessment procedures has not been verified properly. The moment-curvature analysis based on the plane section hypothesis is severely violated especially for reinforced concrete walls. This indicates that a comprehensive investigation is required to investigate the validity of proposed damage limits for structural walls. This study is based on advanced and computationally rigorous numerical procedures to investigate the relation between drift ratio, plastic rotation and curvature, compressive strain in concrete and tensile strain in steel for rectangular reinforced concrete structural walls. Validity of the requirements related to deformation limits in the Turkish Seismic Code and other design guidelines is then evaluated. Modeling and acceptance criteria that are more accurate than the existing ones have been proposed for structural walls.
Citation - WoS: 1
Citation - Scopus: 1
Dynamics of a beam-column element on an elastic foundation
(Canadian Science Publishing, Nrc Research Press, 2016) Dinckal, Cigdem; Dinçkal, Çiğdem; Alemdar, Bulent N.; Gulkan, Polat H.; 26773; 5743; İnşaat Mühendisliği
An exact analytical solution of a harmonically vibrating beam-column element resting on an elastic Winkler foundation is derived. The solution covers four cases comprised of constant compressive or tensile axial force with the restrictions k(s) - m omega(2) < 0 and k(s) - m omega(2) > 0. The proposed solution is not restricted to a particular range of magnitudes of the foundation parameter. Closed form solutions of dynamic shape functions are explicitly derived for each sub-case to obtain frequency-dependent dynamic stiffness terms that constitute the exact dynamic stiffness matrices. Four numerical examples are provided to demonstrate the merits of the present study.
Citation - WoS: 2
Citation - Scopus: 2
Effect of particle size on flip bucket scour
(Canadian Science Publishing, Nrc Research Press, 2016) Kokpinar, Mehmet Ali; Küçükali, Serhat; Kucukali, Serhat; 20413; İnşaat Mühendisliği
This study quantifies the dimensionless maximum scour depth d(s)/D-50 downstream of flip buckets as a function of the square of the densimetric Froude number Fr-d(2), jet Reynolds number Re, lip angle, and sediment non-uniformity constant. The proposed formula is valid for Fr-d = 2.9-29.69, Re = 8.9 x 10(3)-4.2 x 10(5), and We > 32. Moreover, the scour profiles for different sediment sizes (D-50 = 3-17 mm) are presented from the Kigi Dam physical model and the effect of the Reynolds number on scour process is discussed. The prediction capacity of the proposed formula is compared with the existing empirical formulas in the literature and it is shown that the proposed dimensionally homogenous formula made better estimations. The procedure described here has a sound physical basis and it can be used to estimate the maximum scour depth downstream of flip buckets.
Citation - WoS: 1
Citation - Scopus: 1
Effect of sediment properties on incipient motion of large solitary particles on fixed bed
(Emerald Group Publishing Ltd, 2021) Gogus, Mustafa; Haspolat, Emre; 6062
The 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.
Citation - WoS: 1
Citation - Scopus: 3
Effects of collars on local scour around semi-circular end bridge abutments
(Emerald Group Publishing Ltd, 2023) Gogus, Mustafa; Daskin, Sueyla; Gokmener, Serkan
The 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.
Citation - WoS: 9
Citation - Scopus: 14
Evaluation of Tsunami Scenarios For Western Peloponnese, Greece
(Ist Nazionale Di Oceanografia E Di Geofisica, 2014) Yalciner, A. C.; Gulkan, P.; Dilmen, D. I.; Aytore, B.; Ayca, A.; Insel, I.; Zaytsev, A.; 5743
Tsunami hazard assessment of the eastern part of the Mediterranean Sea is the current interest of the countries having, a coastline in this region. Considering today's increasing population on the coasts and historical tsunamis, it is essential to estimate the probable tsunami risk, which might occur, to be able to mitigate the risk before the actual tsunami event happens. For this purpose, European Union funded project., SEAHELLARC is formed to develop a methodology and tools for seismic and tsunami safety and enhance the protection of coastal areas in the western part of Peloponnese in Greece by simultaneous observations and evaluation of onshore and offshore data. In this paper, we present the tsunami simulations of characteristics of possible tsunami source scenarios for the Pylos-Zakynthos-Filiatra and Kyparissia regions, located at western part of Greece. We use NAMIDANCE tsunami simulation and visualization tool to estimate extreme but possible tsunami wave effects in these regions. In the simulations the tsunami arrival times, maximum positive and negative amplitudes are computed, plotted, compared and discussed for the coastal areas of Zakynthos, Filiatra, Kyparissia and Pylos. Furthermore, a detailed mapping of the bathymetric features is performed to define possible landslides and lithological variations at the marine bottom. The uppermost sediments are mapped by sub-bottom profiling, while possible faults are identified by multi-channel reflection mapping at the western Peloponnese. This paper also builds upon the background of a seismic hazard assessment for the region to draw several credible tsunami occurrence scenarios that have been numerically simulated.
Citation - WoS: 16
Citation - Scopus: 25
Flow and Turbulence Structure in A Baffle-Brush Fish Pass
(Ice Publishing, 2018) Kucukali, Serhat; Küçükali, Serhat; Hassinger, Reinhard; 20413; İnşaat Mühendisliği
The 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.
Citation - WoS: 2
Citation - Scopus: 2
Flow Rate along the Length of the Swirling Vortex Axis at an Intake
(Turkish Chamber Civil Engineers, 2021) Tastan, Kerem; Yıldırım, Nevzat; Yildirim, Nevzat; 12654; İnşaat Mühendisliği
In this study, the characteristics of the flow in the region of swirling vortex are examined. The potential flow model based on the summing infinite number of spherical sinks along the vortex core is introduced to predict the flow field and the flow rate along the vortex axis. The flow towards the swirling vortex core has considerable effects on the radial velocity distribution within the ambient fluid flow region near the intake. The agreement between available test data relating to the radial velocity and the method introduced in this study is found to be satisfactory.
Citation - WoS: 0
Citation - Scopus: 0
Frame finite element model for nonlinear and vibration analysis of steel structures with Beam-Column and Column-Base Semi-Rigid Connections
(Gazi Univ, Fac Engineering Architecture, 2022) Ozel, Halil Firat; Özel, Halil Fırat; Saritas, Afsin; 237150; İnşaat Mühendisliği
In this paper, a shear deformable force-based frame finite element with semi-rigid connections is derived for nonlinear analysis of steel structures. Distributed plasticity approach is defined along element length and section depth, and linear or non-linear semi-rigid connection behavior can be specified anywhere along elements without the necessity to define additional nodes and to increase the degrees of freedom of the structural system. To perform vibration analyses with similar accuracy, force-based consistent mass matrix is used considering semi-rigidity in connections and an appropriate shear correction coefficient for I-sections. The element formulation is presented in 2 dimensions to simplify the formulation, and numerical validation and comparison studies are carried out on complex and irregular structures in 2-D and 3-D. In models with semi-rigid connections, the effect of nonlinear behavior on the structural system has been studied in both beam-column and column-bases. In the presented examples, it was possible to push structures higher than the existing displacements, and it was revealed that the nonlinear behavior in the column-base connections could create much more critical results for the structural systems with P-Delta effects. In addition, high-level accuracy results were obtained when performing vibration analyses with the application of force-based consistent mass matrix.
Citation - WoS: 15
Citation - Scopus: 14
Free Vibration Analysis of Carbon Nanotubes by Using Finite Element Method
(Springer, 2016) Dinckal, C.; Dinçkal, Çiğdem; 26773; İnşaat Mühendisliği
In the present study, an efficient and accurate finite element model for vibration analysis of carbon nanotubes (CNTs) with both Euler-Bernoulli and Timoshenko beam theory has been presented. For this purpose, an analytical solution for the exact dynamic shape functions of CNTs based on both Euler-Bernoulli and Timoshenko beam theories has been derived. The solution is general and is not restricted to a particular range of magnitudes of the nonlocal parameters. The exact dynamic shape functions have been utilized to derive analytic expressions for the coefficients of the exact dynamic (frequency-dependent) element stiffness matrix. Numerical results are presented to figure out the effects of nonlocal parameter, mode number and slenderness ratio on the vibration characteristics of CNTs. It is shown that these results are in good agreement with those reported in the literature. Present element formulation will be useful for structural analyses of nanostructures with complex geometries, loadings, material properties and boundary conditions.
Citation - WoS: 11
Citation - Scopus: 14
Hydraulic Model Test Results Of Baffle-Brush Fish Pass
(Ice Publishing, 2015) Kucukali, Serhat; Küçükali, Serhat; Hassinger, Reinhard; 20413; İnşaat Mühendisliği
The 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.
Citation - WoS: 2
Citation - Scopus: 2
Local scour evolution around semi-circular end bridge abutment in quasi-unsteady condition
(Ice Publishing, 2022) Gokmener, Serkan; Gogus, Mustafa; 6062
In 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.
Citation - WoS: 1
Citation - Scopus: 1
The Performance Of Water Jet Pumps And Their Applicatıon In Slurry Transportation
(Turkish Soc thermal Sciences Technology, 2023) Kokpinar, Mehmet Ali; Gogus, Mustafa; 6062
This present work is focused firstly on an experimental investigation for the optimum design of water jet pumps to be used in the hydrotransport of solid particles through pipeline systems. Experiments were conducted in a closed test loop using five types of jet pumps with various dimensions of the driving nozzle, suction nozzle, mixing chamber, and diffuser employing water as driving and suction fluid. The efficiency of each water jet pump element was analyzed and interpretations of results related to each water jet pump were made about the parts to be considered in the optimum design of a water jet pump. From the experimental results, the water jet pump having the optimum mixing chamber, suction nozzle, driving nozzle location, and cross-sectional dimensions produced a maximum efficiency of about 33%. In the second part of the study, the solid particle carrying capacity of water jet pumps in a pipeline system was studied under saltation, moving bed, and heterogeneous flow regimes by introducing seven different types of solid particles having various concentrations into the closed test loop. The effect of jet pumps on separating solid particles from flow in a region was investigated. A curved form of a by-pass system called the 'flow division unit' was added to the main pipeline system and through the flow division unit, then most of the solid particles in the flow were forced to flow towards the suction pipe of the jet pump. As a result of this, only water with very small particle concentrations passed through the centrifugal pumps, and in this way, the wear risk of the centrifugal pump was reduced considerably.

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