İnşaat Mühendisliği Bölümü Yayın Koleksiyonu
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Article Citation - WoS: 9Citation - Scopus: 20An Analysis on the Relationship Between Safety Awareness and Safety Behaviors of Healthcare Professionals, Ankara/Turkey(Oxford Univ Press, 2020) Uzuntarla, Fatma; Kucukali, Serhat; Uzuntarla, YasinObjectives: This descriptive study aims to examine the relationship between the safety awareness of healthcare professional and their safety behaviors. Methods: The study was carried out on 418 healthcare professionals working in a training and research hospital in Ankara/Turkey. The survey method was used as data collection tool. The questionnaire consisted of 3 sections and 18 questions. First section consisted of questions on sociodemographic characteristics and, second section consisted of the awareness scale and third section consisted of safety behaviors scale. Results: The safety awareness and safety behaviors are scored on a scale from 1 (completely disagree) to 5 (completely agree). The safety awareness and safety behaviors has an average score of 3.85 +/- 0.81 and 3.56 +/- 0.82, respectively. The safety awareness and safety behavior levels of healthcare professionals were found to be high. Conclusion: A significant positive correlation was found between safety awareness and safety behaviors and it was concluded that the increase in safety awareness led to an increase in safety behavior.Editorial Citation - WoS: 22Citation - Scopus: 26A Dispassionate View of Seismic-Hazard Assessment(Seismological Soc Amer, 2013) Gulkan, PolatArticle 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, HasanImpact 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 specimensArticle Citation - WoS: 4Citation - Scopus: 7The Performance of Water Jet Pumps and Their Application in Slurry Transportation(Turkish Soc thermal Sciences Technology, 2023) Kokpinar, Mehmet Ali; Gogus, MustafaThis 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.Article Citation - WoS: 22Citation - Scopus: 27Measuring Fluid Flow and Heat Output in Seafloor Hydrothermal Environments(Amer Geophysical Union, 2015) Germanovich, Leonid N.; Hurt, Robert S.; Smith, Joshua E.; Genc, Gence; Lowell, Robert P.We review techniques for measuring fluid flow and advective heat output from seafloor hydrothermal systems and describe new anemometer and turbine flowmeter devices we have designed, built, calibrated, and tested. These devices allow measuring fluid velocity at high-and low-temperature focused and diffuse discharge sites at oceanic spreading centers. The devices perform at ocean floor depths and black smoker temperatures and can be used to measure flow rates ranging over 2 orders of magnitude. Flow velocity is determined from the rotation rate of the rotor blades or paddle assembly. These devices have an open bearing design that eliminates clogging by particles or chemical precipitates as the fluid passes by the rotors. The devices are compact and lightweight enough for deployment from either an occupied or remotely operated submersible. The measured flow rates can be used in conjunction with vent temperature or geochemical measurements to obtain heat outputs or geochemical fluxes from both vent chimneys and diffuse flow regions. The devices have been tested on 30 Alvin dives on the Juan de Fuca Ridge and 3 Jason dives on the East Pacific Rise (EPR). We measured an anomalously low entrainment coefficient (0.064) and report 104 new measurements over a wide range of discharge temperatures (5 degrees-363 degrees C), velocities (2-199 cm/s), and depths (1517-2511 m). These include the first advective heat output measurements at the High Rise vent field and the first direct fluid flow measurement at Middle Valley. Our data suggest that black smoker heat output at the Main Endeavour vent field may have declined since 1994 and that after the 2005-2006 eruption, the high-temperature advective flow at the EPR 9 degrees 50'N field may have become more channelized, predominately discharging through the Bio 9 structure. We also report 16 measurements on 10 Alvin dives and 2 Jason dives with flow meters that predate devices described in this work and were used in the process of their development. This includes the first advective measurements in the Lau Basin and at the EPR 9 degrees 39.5'N. We discuss potential error sources and how they may affect the accuracy of measurements by our devices and other devices. In particular, we use the turbulent plume theory to evaluate the effect of entrainment of ambient seawater.Article Citation - WoS: 30Citation - Scopus: 32Risk Scorecard Concept in Wind Energy Projects: an Integrated Approach(Pergamon-elsevier Science Ltd, 2016) Kucukali, SerhatThe 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.Article Citation - WoS: 2Citation - Scopus: 2Effect of Particle Size on Flip Bucket Scour(Canadian Science Publishing, Nrc Research Press, 2016) Kucukali, Serhat; Kokpinar, Mehmet AliThis 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.Conference Object Conference Object Seismic behavior of a four-legged masonry minaret(2012) Kazaz, İ.; Akansel, V.; Gülkan, Polat; Kazaz, E.The four-legged Minaret of Sheikh Mutahhar Mosque has been constructed in the early 16th century during the Aq Qoyunlu Period in Diyarbakır, Turkey, which is located in the second most hazardous zone of the Turkish Seismic Zones Map. This is a special structure, because the minaret body has been placed on four cylindrical stone columns. Therefore, this minaret is seemingly vulnerable though it has survived for five centuries. We use the square cross sectioned minaret as a possible large-scale seismograph to examine the possible limits of ground motion that must have affected it without causing its collapse. In order to investigate the likely seismic performance and strength of the four-legged minaret, a model, which is very close to real structure, was generated with explicit dynamic code LS-DYNA. The developed model takes into account the material nonlinearities and the interface friction and contact behavior between the masonry units. It was displayed that the amplitude of the ground motion in Diyarbakır could not be 0.15g.Article Citation - WoS: 78Citation - Scopus: 92Finding the Most Suitable Existing Hydropower Reservoirs for the Development of Pumped-Storage Schemes: an Integrated Approach(Pergamon-elsevier Science Ltd, 2014) Kucukali, SerhatThis study aims to evaluate existing hydropower reservoirs for the development of pumped-storage schemes by using multi-criteria scoring technique. This method enables a screening of existing hydropower reservoirs, in order to assess and rank potential sites for pumped-storage development. This analysis is based on the documented evidence, measured data, and site surveys. The site assessments are categorized in 6 criteria namely geometrical conditions (maximum head, head to water way length ratio, distance to grid connection), geological conditions, environmental, and social conditions. In the context of the study, 7 existing hydropower reservoirs in Turkey, each with a catchment area of more than 50 km(2), are evaluated in order to be utilized as the lower reservoirs of pumped-storage facilities. The overall score of each candidate site is obtained and, their performance is compared. The results indicate that Turkey have suitable existing hydropower reservoirs for the development of pumped-storage facilities. However, the country lacks from legal and market framework for the establishment of pumped-storage power plants. (C) 2014 Elsevier Ltd. All rights reserved.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: 10Citation - Scopus: 14A Metaheuristic-Guided Machine Learning Approach for Concrete Strength Prediction With High Mix Design Variability Using Ultrasonic Pulse Velocity Data(Elsevier, 2023) Selcuk, S.; Tang, P.Assessment of concrete strength in existing structures is a common engineering problem. Several attempts in the literature showed the potential of ML methods for predicting concrete strength using concrete properties and NDT values as inputs. However, almost all such ML efforts based on NDT data trained models to predict concrete strength for a specific concrete mix design. We trained a global ML-based model that can predict concrete strength for a wide range of concrete types. This study uses data with high variability for training a metaheuristic-guided ANN model that can cover most concrete mixes used in practice. We put together a dataset that has large variations of mix design components. Training an ANN model using this dataset introduced significant test errors as expected. We optimized hyperparameters, architecture of the ANN model and performed feature selection using genetic algorithm. The proposed model reduces test errors from 9.3 MPa to 4.8 MPa.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: 3Citation - Scopus: 3Flow Rate Along the Length of the Swirling Vortex Axis at an Intake(Turkish Chamber Civil Engineers, 2021) Yildirim, Nevzat; Tastan, KeremIn 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.Article Açılı Cfrp Ankrajlı Şeritler ile Beton Yüzey Arasındaki Gerilme Deformasyon Davranışı için Yeni Bir Model Önerisi(2020) Özgür, A. C. Anıl; Ghoroubi, Rahim; Mercimek, ÖmerBetonarme, çelik veya yığma yapılar birçok farklı nedenden dolayı güçlendirilmeleri veya onarılmaları gerekmektedir. Karbon takviyeli elyaf kumaşlar (CFRP) deprem performansı yetersiz yapıların onarım ve güçlendirme çalışmalarında son 20 yıldır yaygın olarak kullanılmaktadır. CFRP ile geliştirilen onarım ve güçlendirme detaylarında önemli olan tasarım kriterlerinden biri CFRP elemanların yüzeyden soyulmalarını geciktirmektir. Bu amaçla CFRP ile geliştirilen güçlendirme detaylarında ankrajların kullanılması artış göstermiştir. Güçlendirme detaylarında kullanılan fan tipi CFRP ankrajlı CFRP şeritler ile ilgili gerilme-kayma deplasmanı modellerinin ankrajsız CFRP şeritlere göre çok daha sınırlı sayıda olduğu görülmektedir. Bu konudaki sınırlı sayıdaki çalışmada ankrajlar CFRP şeritlere uygulanan eksenel çekme kuvvetine göre 90o açılı olacak şekilde yerleştirilmiştir. Yapılan literatür taramasında eksenel yüke göre değişik açılarda yerleştirilen ankrajlı CFRP şeritlerin eksenel kuvvet taşıma gücü ve gerilme kayma deplasmanı modelleri ile ilgili bir çalışmaya rastlanmamıştır. Bu nedenle deneysel bir çalışma düzenlenmiş ve 28 adet beton yüzeyine yapıştırılan açılı ankrajlı CFRP şerit deney elemanı eksenel çekme kuvveti etkisinde yazarlar tarafından tasarlanan bir deney düzeneği kullanılarak test edilmiştir. Deneysel çalışmada incelenen değişkenler CFRP şerit genişliği ve CFRP şeritler üzerindeki CFRP fan tipi ankrajların açılarıdır. Deneysel çalışma sonucunda açılı ankrajlı CFRP şeritlerin maksimum taşıma gücü değerlerinin hesaplanması için bir denklem ve yeni bir gerilme kayma deplasmanı modeli önerilmiştir.Article Citation - WoS: 2Citation - Scopus: 2Site-Structure Resonance as a Proxy for Structural Damage(Earthquake Engineering Research inst, 2011) Lang, Dominik H.; Schwarz, Jochen; Gulkan, PolatSince 1992, the reconnaissance teams of the German Task Force for Earthquakes have undertaken numerous field missions to disaster areas after strong earthquakes worldwide. During these missions, a unique database of damage cases has been collected, which serves as the basis for examining whether site-structure resonance effects contribute to building damage. The selected buildings that partly experienced slight to moderate damage during a recent major event have been experimentally tested in order to identify their structural parameters and to allow a calibration of the structural building models. In addition, instrumental noise recordings were made directly at the building sites to derive the ranges of predominant site periods. By correlating the ranges of predominant site periods with the building's capacity curves, representing the inelastic displacement behavior under lateral effects, a quick survey procedure has been developed to estimate the impact of agreements between periods of the site and the structure contributing to structural earthquake damage. [DOI: 10.1193/1.3651403]Article Citation - WoS: 1Citation - Scopus: 2Hydraulics of Circular Bottom Intake Orifices(Wiley, 2021) Gogus, Mustafa; Bulut, Muhammed; Ucar, MuhammedIn 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.Publication On the properties of piezoelectric materials based upon orthonormal representations(CRC Press-Taylor, 2013) Dinçkal, ÇiğdemFor piezoelectric tensor, the decomposition method based upon irreducible orthogonal representation is overviewed. Besides, orthonormal tensor basis method is improved to express any third rank tensors such as piezoelectric tensor showing the piezoelectric effect of the material properties on the structures. Numerical examples for materials from different crystal symmetry classes serve to illustrate and verify the orthonormal tensor basis method. The differences and similarities are stated by comparing the methods presented in this work and the others in literature. It is also demonstrated that for hexagonal symmetry, each decomposed parts obtained from orthonormal tensor basis method has physical meaning. Furthermore, the norm based upon orthonormal tensor basis representation of piezoelectric tensor is obtained explicitly for each crystal symmetry classes and those results are used to study the piezoelectric effect of different materials. It is also shown that one can determine in which material the piezoelectric effect is stronger by using the norm concept for any material from various crystal symmetry classes.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 Adaptation of generalized Hill inequalities to anisotropic elastic symmetries(2011) Dinçkal, ÇiğdemMechanical and elastic behaviors of anisotropic materials are investigated in an innovative way. This is based on generalized Hill inequalities. From different type of anisotropic elastic symmetries, numerical examples are given. Constructing bounds on effective eigenvalues provides a deeper understanding about mechanical behavior of anisotropic materials. Generalized Hill inequalities are adapted to all anisotropic elastic symmetries. The materials selected from the same symmetry type which have larger interval between the bounds, are more anisotropic whereas smaller interval between the bounds, are closer to isotropy. Besides it is proved that there are relations between bulk and shear modulus and eigenvalues of cubic and isotropic symmetry and by these relations, two linear invariants are found out.
