Mühendislik Fakültesi

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A Case Study of Structural Failure of Mounting Systems for Solar Panels from South-Eastern Turkey: An Investigation of Design Parameters under Extreme Weather Events
(2019) Çelik, Gence Genç; Çelik, O.; 101566
One of the biggest demand of growing population, and cornerstone of the socio-economical growth of Nations, Energy is expected today to be Sustainable, Easy to Reach, Economical, and Continuous. As one of the most common and imperative contributors of this Clean Energy Future, Solar Energy in various forms takes a significant role whole around the World. And It shows a great potential particularly for Turkey which imports the majority of its Energy Resources - including Conventional Ones - from Out Sources, to decrease Energy Dependency on Out-of-country Bases and increase awareness to develop competition in New Technology and Production Fields. Based on a Structural Failure Case of Supporting Frames designed for Solar Photovoltaics (PV) in a Solar Power Plant from Turkey, this paper addresses the significance of Local and Site-Specific Investigation of Climate Data to properly decide on Structural Design Parameters -particularly Loads of Snow and Wind- by staying still comformable with National Codes and Standards.
A New Novel Model Proposal For Bond-Slip Behavior Between Angular CFRP Fan Type Anchoraged CFRP Strip and Concrete Surface
(2020) Ghoroubi, Rahim; Mercimek, Ömer; Anıl, Özgür; 306045
In the reinforced concrete, masonry or steel structures should be strengthened or repaired. Carbon fiber reinforced polymers (CFRP) have been widely used for the last 20 years for repairing and strengthening of inadequate earthquake performance of the structures. One of the most important developed design criteria in the retrofit and strengthening details are using CFRP to delay the debonding of the CFRP reinforcement elements. For this reason, the uses of anchors in the reinforcement details developed by using CFRP and also researches on this subject have increased substantially. In the literature, research on bond-slip models developed for fan type CFRP anchors and anchored CFRP strips used in reinforcement details are limited in comparison to non-anchored strips. However, in studies on this subject, anchors are placed at 90o to the axial tensile force applied to the CFRP strips. Axial force-bearing strength and bond-slip models of CFRP strips with the different anchored angle under axial tensile strengths have not been found in the literature. For this reason, an experimental study was carried out and 28 specimens of angled anchored CFRP strip test specimen, which was bonded to the concrete surface, was tested under the influence of axial tensile force with an experimental setup designed by the authors. The variables studied in the experimental study are the CFRP strip width and the fan type CFRP anchor angle placed on the CFRP strip. As a result of the experimental study, an equation was proposed for calculating the bearing strength values of angled anchored CFRP strips and a new proposal for the bond-slip model was developed.
A Predictive Ground-Motion Model for Turkey and Its Comparison with Recent Local and Global GMPEs
(2011) Cağnan, Zehra; Akkar, Sinan; Gülkan, Polat; 5743
We present a local ground motion prediction equation (GMPE ) for estimating the peak ground-motion values that was derived using the recently compiled Turkish strong motion database . The new GMPE is comparable with the recent global GMPEs in terms of model sophistication and quality of underlying database. Using this equation, we explore the inter-event , inter-station ground motion variability of the recent Turkish strong motion database as well as suitability of some local and global GMPEs for regional seismic hazard assessment analyses. The inter-event error underlines the distinguishing characteristics of few earthquakes, suggesting that the use of local GMPEs can be important especially when specific scenario studies are to be carried out. The inter-station variability allowed us to detect stations with outlier site response and to investigate the goodness of the employed site effect s model. Results also indicate suitability of some global and local GMPEs for use in regional seismic hazard assessments together with the model presented in this study. These should be combined through a logic tree scheme to reduce both aleatory and epistemic uncertainty in local hazard assessments.
Adaptation of generalized Hill inequalities to anisotropic elastic symmetries
(2011) Dinçkal, Çiğdem; 26773; İnşaat Mühendisliği
Mechanical 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.
An investigation of the hydrodynamic and fish behavior characteristics of the brush-type fish passage: Iyidere (Turkey) field study
(2017) Küçükali, Serhat; 20413; İnşaat Mühendisliği
Analysis of Elastic Anisotropy of Wood Material for Engineering Applications
(2011) Dinçkal, Çiğdem; 26773; İnşaat Mühendisliği
This paper presents a convenient method to describe the degree of the elastic anisotropy in a given type of wood and then discusses its practical values. Besides mechanical and elastic behaviour of wood are investigated in order to understand the optimum mechanical behaviour of it in selected directions. Bounds on the wood elastic constants have been constructed in terms of elasticity and compliance tensors for any type of woods by developing Hill (1952) approach. So for any type of wood with known elastic constants, it is possible to choose the best set of elastic constants (effective elastic constants) which determine the optimum mechanical and elastic properties of it. Bounds on the wood elastic constants as well as the degree of elastic anisotropy are significant and critical cases in design of any engineering and structural materials made up of wood.
Biogas Energy in Turkey: Current Situation, Sustainability and Policy Implications, Energy Science and Technology
(2014) Küçükali, Serhat; Küçükali, Serhat; 20413; İnşaat Mühendisliği
Birden Fazla Boşluklu Çift Doğrultulu Betonarme Döşemelerin Zımbalama Performansının İyileştirilmesi için Tekstil ile Güçlendirilmiş Sıva Şeritler ile Güçlendirilmesi
(2021) Mercimek, Ömer; Ghoroubi, Rahim; Anıl, Özgür; Baran, Mehmet
Betonarme kirişsiz döşemelerde meydana gelebilecek olan ani ve gevrek bir şekilde, hiçbir deformasyon belirtisi göstermeden oluşan zımbalama göçme mekanizması yapı içerisinde yaşayanlara zarar verebilecek son derece tehlikeli bir göçme şeklidir. Bu nedenle tasarım aşamasında kaçınılan göçme mekanizmalarının başında gelmektedir. Betonarme döşemelerde havalandırma, elektrik veya dogalgaz gibi alt yapı sistemlerinin geçirilmesi veya merdiven ya da asansör boşluğu gibi mimari zorunluluklar nedeniyle bırakılan boşlukların, döşemelerin zımbalama dayanımını ve davranışını olumsuz etkilediği bilinmektedir. Ancak birden fazla boşluklu çift doğrultulu betonarme döşemelerin zımbalama yüklemesi etkisi altındaki davranışının incelendiği bir araştırmaya literatürde rastlanmamıştır. Bu nedenle betonarme çift doğrultulu döşemelerde birden fazla boşluğun döşemelerin zımbalama davranışı üzerindeki olumsuz etkilerinin belirlenmesi ve boşlukların meydana getirdiği davranış problemlerinin azaltılabilmesi için tekstil ile takviye edilmiş sıva şeritler ile döşemelerin güçlendirilmesinin incelendiği deneysel bir çalışma planlanmıştır. Bu çalışma kapsamında biri boşluksuz referans elemanı, 4 deney elemanı ise 300x300 mm boyutlarında kare kesitli iki adet boşluklu olacak şekilde toplamda 5 döşeme deney elemanı üretilmiştir. Boşluklu deney elemanlarının ikisi tekstil ile güçlendirilmiş sıva katmanlı (TGSK) şeritler ile güçlendirilerek deney elemanlarının zımbalama davranışı üzerinde boşlukların meydana getirdiği olumsuz etkilerin ne ölçüde iyileştirilebildiği deneysel olarak araştırılmıştır. Çalışma kapsamında TGSK şeritler ile geliştirilen ve uygulanan güçlendirme metodunun döşemelerin zımbalama dayanımını önemli ölçüde artırdığı, boşlukların meydana getirdiği olumsuz etkileri sınırlandırdığı görülmüştür.
Brush-baffle fish pass: a continuous migration corridor for fish
(2016) Küçükali, Serhat; 20413; İnşaat Mühendisliği
Buildings Subjected to Recurring Earthquakes: A Tale of Three Cities
(2011) Bayhan, Beyhan; Polat, Gülkan; 5743
Three different buildings built according to the same design have experienced three different near-field strong ground motions over a period of 11 years in three different cities in Turkey. The input motion was known for each because strong-motion sensors were located adjacent or close to the buildings. We examine the performance of the five-story, reinforced concrete-frame buildings. Bidirectional nonlinear time history and nonlinear static analyses on 3-D analytical models are performed. The principal focus is to assess whether the analytical model of the buildings could indicate column-beam damage consistent with that observed at the sites after the earthquakes. Results illustrate that nonlinear time history analyses are capable of indicating the occurrence of shear failure in captive columns; however, they overestimate the global damage. The overestimation is greater where the building sustained a pulse-type motion without significant distress. It appears that difference between visual observations and analytical results persists.
Cuckoo Search Based Backcalculation Algorithm for Estimating Layer Properties of Full-Depth Flexible Pavements
(Springer, 2021) Öcal, Arda; Pekcan, Onur; İnşaat Mühendisliği
This book highlights the basic concepts of the CS algorithm and its variants, and their use in solving diverse optimization problems in medical and engineering applications. Evolutionary-based meta-heuristic approaches are increasingly being applied to solve complicated optimization problems in several real-world applications. One of the most successful optimization algorithms is the Cuckoo search (CS), which has become an active research area to solve N-dimensional and linear/nonlinear optimization problems using simple mathematical processes. CS has attracted the attention of various researchers, resulting in the emergence of numerous variants of the basic CS with enhanced performance since 2019.
Determination of Optimum Bitumen Content in Porous Asphalt Pavement by Different Methods
(2022) İbiş, Ahmet Buğra; Şengöz, Burak; almusawi, Ali; Kaya Özdemir, Derya; Topal, Ali
In recent years, studies on porous asphalt have gained more importance and countries are conducting various studies in order to improve the engineering properties of this type of pavement. As a result of these studies, each country developed its own standard and therefore different optimum bitumen content (OBC) determination methods emerged. This paper investigates the determination of the optimum bitumen content of porous asphalt samples prepared by using different aggregate types and polymers by the methods implemented in Turkey and in other countries. The results have shown that the application of each method yielded different bitumen content.
Developments in International Bridge Engineering
(2021) Gülkan, Polat; Caner, Alp; Memişoğlu Apaydın, Nurdan
This book reports on current challenges in bridge engineering faced by professionals around the globe, giving a special emphasis to recently developed techniques and methods for bridge design, construction and monitoring. Based on extended and revised papers selected from outstanding presentation at the Istanbul Bridge Conference 2018, held from November 5 – 6, 2018, in Istanbul, Turkey, and by highlighting major bridge studies, spanning from numerical and modeling studies to the applications of new construction techniques and monitoring systems, this book is intended to promote high standards in modern bridge engineering. It offers a timely reference to both academics and professionals in this field.
Displacement Induced Torsion in Structures
(2012) Masoudi, M.; Gülkan, Polat; Dazio, A.; 5743
Satisfying the equations of motion in the deformed configuration leads to actions that inherently contain secondary effects. Similar to the product of vertical loads and lateral displacements which leads to the PΔ effect in structures, lateral displacements may cause significant secondary torsion due to the presence of lateral loads. A simple finite-element formulation is presented in the paper to capture this effect. This formulation is verified by means of the Corotational approach and the updated Lagrangian formulation for acceptable drift limits in structural engineering practice. A simple single-story structure and a 7-story RC and steel structures with no predefined mass eccentricity are subjected to an ensemble of bi-axial ground motions recorded on different soil conditions to demonstrate secondary effects. The paper shows that when the period of the structure is not identical in the two horizontal directions secondary torsion is important and may result in significant torsional amplification.
Ecological Assessment: Use of Hydropower and Biogas Energy in Waste Water Treatment Plants
(CRC Press, 2018) Küçükali, Serhat; Ar, I. İrfan; Ak, Mümtaz; Günal, Asiye; 20413; İnşaat Mühendisliği
Effect of dual pipe intakes dimensions and positions on critical submergence
(2019) Yıldırım, Nevzat; Yıldırım, Nevzat; 12654; İnşaat Mühendisliği
Effect of intake entrance geometry on the critical submergence
(2019) Yıldırım, Nevzat; Yıldırım, Nevzat; 12654; İnşaat Mühendisliği
Effect of the Bed-Sediment Layer on the Scour Caused by a Jet
(2016) Yıldırım, Nevzat; Koçak, Peli̇n Pınar; Yıldırım, Nevzat; 12654; İnşaat Mühendisliği
Scour caused by a water jet impinging the bedsediment layer is a significant concern for hydraulic engineers. Although several studies investigated the maximum scour depth on the non-cohesive bed-sediment layer, the effect of the bed-sediment layer’s thickness on the scour was not studied. This study investigated the effect of the thickness of the non-cohesive sediment layer at the canal bed on the depth of the scour caused by a water jet. The dimensionless parameters affecting the depth of the scour were obtained via dimensional analysis. Experiments were conducted on two different, non-cohesive bed-sediment layers at the bottom of a rectangular canal for different jet Froude numbers. Experimental results indicated that the depth of the scour increases with the thickness of the bed-sediment layer; this is because as the thickness of the sediment layer increases, the penetration depth of the air bubbles (dragged and enforced by the impinging water jet) through the sediment layer just under the scour hole increases. Due to the buoyancy force, as the air bubbles rise upward, they apply uplift forces and dynamic effects onto sediment particles, dislodging, suspending, and carrying the sediment particles away from the bed. If the thickness of the sediment layer is increased beyond a limiting value for a given flow condition, the maximum depth of the scour does not change (it remains almost constant). The effect of the thickness of the bed-sediment layer on the depth of the scour is present but not excessively large.
Effective intake for critical submergence in the case of more than one intake
(2017) Yıldırım, Nevzat; Yıldırım, Nevzat; 12654; İnşaat Mühendisliği
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.
Examination of code performance limits for shear walls
(2012) Kazaz, İ.; Gülkan, Polat; Yakut, A.; 5743
Recently proposed changes to modeling and acceptance criteria in seismic regulations for both flexure and shear dominated reinforced concrete structural walls suggest that a comprehensive examination is required for improved limit state definitions and their corresponding values. This study utilizes a well calibrated modeling tool to investigate the deformation measures defined in terms of plastic rotations and local concrete and steel strains at the extreme fiber of rectangular structural walls. We compare requirements in ASCE/SEI 41, Eurocode 8 and the Turkish Seismic Code. This way, a critical evaluation of the requirements embedded in these documents becomes possible. It is concluded that the performance limits must be refined by introducing additional parameters. Significant recommendations are provided for Eurocode 8 and the Turkish Seismic Code.

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