İnşaat Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/395

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Performance-Based Seismic Evaluation and Retrofitting of Historic Unreinforced Concrete Wall Buildings With Interior Steel Frames
(Dolnoslaskie Wydawnictwo Edukacyjne-dwe, 2012) Gunes, Oguz; Güneş, Oğuz; Gunes, Burcu; Sozenoglu, Ismet; İnşaat Mühendisliği
Performance-based seismic evaluation of historical constructions is a challenge due to the difficulty of their structural analysis that accurately captures their nonlinear behavior. This paper focuses on the use of 3-D nonlinear finite element method for static pushover analysis of unreinforced concrete (URC) wall buildings with interior steel frames for seismic evaluation and retrofit design. Three such historical school buildings with different levels of structural complexity were modeled in detail using advanced finite element programs to obtain their linear and nonlinear behavior under monotonically increasing lateral loads. The capacity curves obtained from pushover analyses were used for performance evaluation using the Capacity Spectrum Method. Retrofit design verification for one of the buildings was performed using the same approach. The results show that despite its involved modeling process and computational expense, pushover analysis of buildings with URC/URM elements using 3-D nonlinear finite element method can become a powerful practical tool for improved seismic performance evaluation and retrofit design.
Closure to "local Scour at Triangular Labyrinth Side Weirs Located on an Alluvial Channel" by Mustafa Tunc, Muhammet Emin Emiroglu, and Mustafa Gogus
(2023) Tunç, Mustafa; Emiroğlu, Muhammet Emin; Göğüş, Mustafa
Effective intake for critical submergence in the case of more than one intake
(2017) Taştan, Kerem; Yıldırım, Nevzat
The available potential flow solution methods over-estimate the number of effective intake for the prediction of critical submergence in the case of multiple intakes of identical level without partition walls located on the longitudinal line of the canal, because they cannot establish an upper limiting value for the distance between the centers of the intakes. To address this, tests were conducted on dual intakes of identical level located on the longitudinal line of the canal in a cross-flow. In practice, by means of the chart obtained from the experimental results, one can determine the upper limiting value of the distance between the centers of dual intakes beyond which the effect of the intake on the critical submergence of the other intake is negligible. Such an intake is considered a non-effective intake and is disregarded in the prediction of critical submergence. In addition, the effective intake relating to multiple intakes sited in a still-water reservoir is explained.
Citation - WoS: 8
Citation - Scopus: 8
Dynamic Shear Force Amplification in Regular Frame-Wall Systems
(Wiley-blackwell, 2016) Kazaz, Ilker; Gulkan, Polat
A parametric study is conducted to investigate the dynamic shear amplification factor (DAF) in low-to-mid-rise frame-wall systems in which the reinforcement curtailment along the height matches the required code strength. The level of frame-wall interaction is varied by changing the wall index, defined as the ratio of the total wall area to the floor plan area, in a generic frame-wall system, and its correlation with the DAF is investigated. Wall index values ranging in the 0.2% to 2% interval are selected. Walls with lengths of 3m, 5m and 8m are used in the design of model buildings of 4, 8 and 12 stories. Shear-flexure beam continuum formulation is used in design and modeling. The global behavior is analyzed using nonlinear response history procedure using spectrum compatible ground motions. It is found that the primary source of amplification is the level of inelastic demand on the system. Walls designed for code-specified force reduction factor R=6 experienced an average base shear force amplification in the order of 1.64 with standard deviation of 0.19 with respect to design shear force. Amplification diminishes with decreasing R. An expression for the dynamic amplification factor as a function of the number of stories and force reduction factor R is proposed. Copyright (C) 2015 John Wiley & Sons, Ltd.
An investigation of the hydrodynamic and fish behavior characteristics of the brush-type fish passage: Iyidere (Turkey) field study
(2017) Küçükali, Serhat
The implementation of the european union (EU) water framework directive impact on small hydropower plants: situation in Turkey
(2014) Küçükali, Serhat
Citation - WoS: 30
Citation - Scopus: 32
Risk Scorecard Concept in Wind Energy Projects: an Integrated Approach
(Pergamon-elsevier Science Ltd, 2016) Kucukali, Serhat
The proposed risk assessment tool quantifies economic, environmental, political, and societal risks in wind energy projects. The risks are quantified based on the measured data and document evidence. An important component of the proposed methodology includes converting different external risks into a common scale and these scales express the level of risk factors. A survey was conducted with the experts in order to determine the relative importance of external risks. Applicability of the proposed tool is tested on real time wind power plants that are located in Izmir Province on the Aegean coast of Turkey. Change in laws and regulations, environmental issues, local community, grid connection, land use and permits, and erroneous wind resource assessment appeared to be key risk factors. The findings of case studies showed that the perception of inadequate understanding of the potential risks can lead to significant revenue loss. The proposed method estimates each risk factor level separately and then aggregates them by calculating the Project Risk Score (PRS) which is linked to the normalized revenue loss. (C) 2015 Elsevier Ltd. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Effect of Particle Size on Flip Bucket Scour
(Canadian Science Publishing, Nrc Research Press, 2016) Kucukali, Serhat; Kokpinar, Mehmet Ali
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: 14
Citation - Scopus: 16
Experimental and Numerical Investigation of Rc Column Strengthening With Cfrp Strips Subjected To Low-Velocity Impact Load
(Techno-press, 2021) Mercimek, Omer; Anil, Ozgur; Ghoroubi, Rahim; Sakin, Shaimaa; Yilmaz, Tolga
Reinforced concrete (RC) square columns are vulnerable to sudden dynamic impact loadings such as the vehicle crash to the bridges of highway or seaway, rock fall, the collision of masses with the effect of flood and landslide. In this experimental study RC square columns strengthened with and without CFRP strip subjected to sudden low velocity lateral impact loading were investigated. Drop-hammer testing machine was used to apply the impact loading to RC square columns. The test specimens were manufactured with square cross sections with 1/3 geometric scale. In scope of the study, 6 test specimens were manufactured and tested. The main variables considered in the study were the application point of impact loading, and CFRP strip spacing. A 9.0 kg mass was allowed to fall freely from a height of 1.0 m to apply the impact loading on the columns. During the impact tests, accelerations, impact force, column mid-point displacements and CFRP strip strains measurements were taken. The general behavior of test specimens, collapse mechanisms, acceleration, displacement, impact load and strain time relationships were interpreted, and the load displacement relationships were obtained. The data from the experimental study was used to investigate the effect of variables on the impact performances of RC columns. It has been observed that the strengthening method applied to reinforced concrete columns, which are designed with insufficient shear strength, insufficient shear reinforcement and produced with low strength concrete, using CFRP strips significantly improves the behavior of the columns under the effect of sudden dynamic impact loading and increases their performance. As a result of the increase in the hardness and rigidity of the specimens strengthened by wrapping with CFRP strips, the accelerations due to the impact loading increased, the displacements decreased and the number of shear cracks formed decreased and the damage was limited. Moreover, the finite element analyses of tested specimens were performed using ABAQUS software to further investigate the impact behavior.
Citation - WoS: 1
Citation - Scopus: 2
Hydraulics of Circular Bottom Intake Orifices
(Wiley, 2021) Gogus, Mustafa; Bulut, Muhammed; Ucar, Muhammed
In this study, the hydraulic characteristics of circular bottom intake orifices were investigated in a hydraulic model. The structure diverts the river-flow to a hydroelectric power plant through circular orifices located at the bottom of the channel. In the model, a series of circular holes of various diameters and locations at the bottom of a channel in the form of single and multiple holes were tested for different flowrates and screen angles (theta) to determine the flow diverting capacity of them. Discharges passing through orifices at known locations (x) and diameters (d) and screen slopes (theta) were measured and recorded along with the related main channel flow rates and depths (h). Using the dimensional analysis approach, an expression for the flow rate diverted from the main channel was derived as a function of related parameters, and their variations with each other were presented graphically and empirical equations were determined. Referring to the graphs and empirical equations, one can determine the discharge capacity of single and multiple intake orifices, which is important to calculate the amount of flow to be diverted from the main channel within the ranges of the related parameters used in this study.
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
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: 22
Citation - Scopus: 26
A Dispassionate View of Seismic-Hazard Assessment
(Seismological Soc Amer, 2013) Gulkan, Polat
Citation - WoS: 2
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: 45
Citation - Scopus: 51
Risk Assessment of River-Type Hydropower Plants Using Fuzzy Logic Approach
(Elsevier Sci Ltd, 2011) Kucukali, Serhat
In this paper, a fuzzy rating tool was developed for river-type hydropower plant projects, and risk assessment and expert judgments were utilized instead of probabilistic reasoning. The methodology is a multi-criteria decision analysis, which provides a flexible and easily understood way to analyze project risks. The external risks, which are partly under the control of companies, were considered in the model. A total of eleven classes of risk factors were determined based on the expert interviews, field studies and literature review as follows: site geology, land use, environmental issues, grid connection, social acceptance, macroeconomic, natural hazards, change of laws and regulations, terrorism, access to infrastructure and revenue. The relative importance of risk factors was determined from the survey results. The survey was conducted with the experts that have experience in the construction of river-type hydropower schemes. The survey results revealed that the site geology and environmental issues were considered as the most important risks. The new risk assessment method enabled a Risk Index (R) value to be calculated, establishing a 4-grade evaluation system. The proposed risk analysis will give investors a more rational basis to make decisions and it can prevent cost and schedule overruns. (C) 2011 Elsevier Ltd. All rights reserved.
High-velocity impact of large caliber tungsten projectiles on ordinary Portland and calcium aluminate cement based HPSFRC and SIFCON slabs. Part I: experimental investigations
(Techno-Press, 2011) Polat, Gülkan; Korucu, Hasan
Impact experiments have been carried out on concrete slabs. The first group was traditionally manufactured, densely reinforced concrete targets, and the next were ordinary Portland and calcium aluminate cement based HPSFRC (High performance steel fiber reinforced concrete) and SIFCON (Slurry infiltrated concrete) targets. All specimens were hit by anti-armor tungsten projectiles at a muzzle velocity of over 4 Mach causing destructive perforation. In Part I of this article, production and experimental procedures are described. The first group of specimens were ordinary CEM I 42.5 R cement based targets including only dense reinforcement. In the second and third groups, specimens were produced using CEM I 42.5 R cement and Calcium Aluminate Cement (CAC40) with ordinary reinforcement and steel fibers 2 percent in volume. In the fourth group, SIFCON specimens including 12 percent of steel fibers without reinforcement were tested. A high-speed camera was used to capture impact and residual velocities of the projectile. Sample tests were performed to obtain mechanical properties of the materials. In the companion Part II of this study, numerical investigations and simulations performed will be presented. Few studies exist that examine high-velocity impact effects on CAC40 based HPSFRC targets, so this investigation gives an insight for comparison of their behavior with Portland cement based and SIFCON specimens
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.
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: 6
Citation - Scopus: 8
A Modified Applied Element Model for the Simulation of Plain Concrete Behaviour
(Emerald Group Publishing Ltd, 2023) Soysal, Berat Feyza; Arici, Yalin; Tuncay, Kagan
A modified applied element model to simulate the behaviour of plain concrete continuum structures including discrete cracking is proposed in this study. In the classical applied element model, Poisson effects are fully ignored. To remediate this issue, diagonal elements are introduced to include the Poisson effect, and the constitutive parameters are rigorously determined using the Cauchy-Born rule and the hyper-elastic theory. The formulation is validated for linear elastic problems and the consistency and convergence behaviour of the numerical approach is shown. Tensile softening formulation using the concept of fracture energy is utilised for the nonlinear range. In this range, the approach is validated using the classical benchmark tests with pure tensile, split-tensile, combined shear-tensile and bending dominated push-over loading. The load-displacement behaviour and crack response were captured successfully, showing the proposed methodology can be used to quantify discrete cracks on large systems, such as dam monoliths, from initiation to significant damage levels.
Citation - WoS: 6
Citation - Scopus: 9
Failure Modes in Structural Applications of Fiber-Reinforced Polymer (Frp) Composites and Their Prevention
(Woodhead Publ Ltd, 2013) Gunes, O.
Fiber-reinforced polymer (FRP) composite materials have been increasingly used in civil engineering applications in the past two decades. Their wide ranging use, however, is still not realized due to a few fundamental issues including high material costs, relatively short history of applications and the gaps in the development of established standards. Design safety requires that all possible modes and mechanisms of failure are identified, characterized, and accounted for in the design procedures. This chapter provides a review of the failure types encountered in structural engineering applications of FRP and the preventive methods and strategies that have been developed to eliminate or delay such failures. As part of preventive measures, various non-destructive testing (NDT) and structural health monitoring (SHM) methods used for monitoring FRP applications are discussed with illustrative examples.
Citation - WoS: 20
Citation - Scopus: 28
Flow and Turbulence Structure in a Baffle-Brush Fish Pass
(Ice Publishing, 2018) Hassinger, Reinhard; Kucukali, Serhat
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: 49
Citation - Scopus: 63
Ductility of Frp-Concrete Systems: Investigations at Different Length Scales
(Elsevier Sci Ltd, 2013) Lau, Denvid; Tuakta, Chakrapan; Bueyuekoeztuerk, Oral; Gunes, Oguz
Fiber reinforced polymer (FRP) materials have been increasingly used in the last two decades to improve various structural characteristics of reinforced concrete (RC) bridges, buildings and other structures. Ductility of the resulting FRP-concrete system plays an important role in structural performance, especially in certain applications such as earthquake resistant design of structures, where ductility and energy dissipation play a vital role. Wrapping RC columns with FRP has been shown to generally result in significant increase in ductility due to the confinement of concrete by the FRP. Other applications such as flexural strengthening of beams involve tradeoffs between ductility and the desired load capacity. Furthermore, environmental factors may adversely affect the FRP-concrete bond raising concerns about the ductility of the system due to possible premature failure modes. Characterization of these effects requires the use of more involved mechanics concepts other than the simple elastic or ultimate strength analyses. This paper focuses on characterizing ductility of the FRP-concrete systems at different length scales using a combined experimental/computational mechanics approach. Effects of several parameters on ductility, including constituent material properties and their interfaces, FRP reinforcement geometry at the macro- and meso-level, and atomistic structure at the molecular level are discussed. Integration of this knowledge will provide the basis for improved design strategies considering the ductility of FRP-concrete systems from a global as well as local perspective including interface bond behavior under various mechanical and environmental conditions. (C) 2012 Elsevier Ltd. All rights reserved.

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