Yazarlar
- Sari, Mahmut(2)
- Öztürk, Serkan(2)
- Aksüt, Yavuz Selim(1)
- Altunisik, Ahmet Can(1)
- Araz, Onur(1)
- Ates, Sevket(1)
- Atmaca, Barbaros(1)
- Aydin, Metin Mutlu(1)
- Celen, Ali(1)
- Celen, Pinar(1)
- Cellek, Mehmet Salih(1)
- Cona, Lale(1)
- Dag, Serhat(1)
- Dalkiliç, Ahmet Selim(1)
- Donmez, Aydin Haci(1)
- Ghassemi, Mohammad Reza(1)
- Günaydin, Murat(1)
- Kahya, Volkan(1)
- Karadeniz, Sami(1)
- Karakoyun, Yakup(1)
- Kaya, Yusuf(1)
- Köfteci, Sevil(1)
- Mazlum, Ugur(1)
- Polat, Alper(1)
- Sengül, Kadir(1)
- Taner, Tolga(1)
- Tekin, Sezgin(1)
- Turan, Muhittin(1)
- Vahapoglu, Vahap(1)
- Wongwises, Somchai(1)
- Yetgin, Sukru(1)
- Yildirim, Mehmet Sinan(1)
- Çakir, Tufan(1)
- Çebi, Alican(1)
- Özsahin, Talat Sukru(1)
Yayınlar
- MakaleYayıncıda açık erişim2024Solutions of linear Fredholm integral equations with the three- step iteration method
Cona, Lale; Sengül, Kadir
In this article, the solution of the second type of nonhomogeneous linear Fredholm integral equations is investigated using a three-step iteration algorithm. It has been shown that the sequences obtained from this algorithm converge to the solution of the mentioned equations. Morever, data dependency is obtained for the second type of nonhomogeneous linear Fredholm integral equations. This result is supported by an example.
- MakaleYalnız künye2018EMPIRICAL RELATIONS AMONG THE PARAMETERS ASSOCIATED WITH EARTHQUAKE RUPTURE MECHANISMS FOR IRANIAN EARTHQUAKES
Öztürk, Serkan; Ghassemi, Mohammad Reza; Sari, Mahmut
In this study, we aimed to derive the new and more reliable empirical relationships among different seismic parameters associated with the earthquake rupture mechanisms for Iranian earthquakes. For this purpose, we firstly converted the surface wave magnitudes into moment magnitudes in order to prepare a uniform earthquake dataset. Thereafter, we estimated the empirical relationships between moment magnitude and surface rupture length, moment magnitude and maximum displacement, and surface rupture length and maximum displacement. These linear empirical equations were obtained by orthogonal regression and the goodness of fits were discussed in terms of the correlation coefficients. The results obtained by the orthogonal regression in this paper are compared with the results obtained by the least square method in the literature. The present study confirms that representations of statistical correlations among different earthquake faulting parameters can be given more clear and straightforward by the orthogonal regression as compared to the least square method. In addition, such kind of relationships may provide some significant insights for the calculation of the maximum surface rupture length, maximum surface displacement, and associated maximum credible earthquakes for different seismotectonic regions of Iran as well as the estimation of earthquake magnitudes in paleoseismological studies.
- MakaleYalnız künye2018DETECTION OF THE COMPLEX GROUND PROBLEMS BY GROUND PENETRATING RADAR: EXAMPLES FROM GUMUSHANE UNIVERSITY
Sari, Mahmut; Öztürk, Serkan
In this study, Ground Penetrating Radar (GPR) technique was used for the detection of i) the reasons of deformations which occur in the field ground of Gumushane University Sport Complex (GUSC), and ii) the congestion in flow pipe of Gumushane University, Engineering and Natural Sciences Faculty (GUENSF). GPR data was collected by using the RAMAC CU II device and a shielded antenna with a 500 MHz center frequency. The wave fields for GUSC were examined by 2D and 3D processing. The large-scaled hyperbolic reflections are in corresponds to the areas where the field ground has deformations. It is considered that these anomaly areas may include a gap or a padding having a large gap and suggested that these damaged areas must be full with hard materials. The large-scaled hyperbolic reflections approximately starts in one-meter depth and reaches three-meters. For GUENSF, the measurements were conducted on the route where the main flow pipe crosses. In GPR sections, hyperbolas with high amplitudes were observed in the zones where flow pipe passes. Information on slope of flow pipe was provided by examining the association of these hyperbolas with the depth, and the clogged zones were detected. It is stated that unclogging the clogged zones of the flow pipe will not fully contribute to the resolution of the problem. Therefore, it is suggested to provide necessary slope to the flow pipe by completely removing and mounting back. These results show that GPR technique is an effective tool to provide a good image and solution for the complex ground problems.
- MakaleYalnız künye2018TRIP OPTIMIZATION FOR PUBLIC TRANSPORTATION SYSTEMS WITH LINEAR GOAL PROGRAMMING (LGP) METHOD
Tekin, Sezgin; Köfteci, Sevil; Aydin, Metin Mutlu; Yildirim, Mehmet Sinan
Determination of the optimum trip schedules is an important problem for public transportation systems. It is complex task to assign optimum number of vehicles and determine the trip schedules for a public transport systems which consist of many routes. In the case of taking infrequent trip schedules, the existing passenger demand is not satisfied. Therefore waiting times are increased in the bus stops. In contrary, with more frequent intervals, unutilized capacity and higher operational costs are expected. Also, intense traffic density and environmental pollution are associated with the frequent trips. The optimum trip frequencies of the passenger demands varies during the hours of a day and is important for passenger satisfaction and operation efficiency of the system. Trip scheduling and vehicle assignment studies take attention in the current literature assisted with different optimization techniques and artificial intelligence method. In this study, only 10 different bus routes which is operated privately, were considered in the city center of Antalya and the Linear Goal Programming (LGP) was used to determine the optimum number of vehicles operated on the routes. The study results showed that the existing system performance can be preserved by reducing the frequency of specific trips and LGP is stated as an efficient algorithm for determining the optimum trip frequencies and number of vehicles in a public transportation systems.
- MakaleYalnız künye2018COMPARISON OF FEM SOLUTION WITH ANALYTICAL SOLUTION OF CONTINUOUS AND DISCONTINUOUS CONTACT PROBLEM
Kaya, Yusuf; Polat, Alper; Özsahin, Talat Sukru
The continuous and discontinuous contact problem of a homogeneous layer loaded with three rigid flat blocks and resting on the elastic semi-infinite plane was investigated in this study by using the finite element method (FEM). All surfaces are assumed to be frictionless. The homogenous layer was loaded by means of three rigid flat blocks whose external loads are Q and P (per unit thickness in z direction). Two dimensional finite element analysis of the problem was performed using ANSYS package program. Analyzes were performed for loading conditions which are Q=P, Q=2P, Q=4P, Q=8P and Q=10P, and different values of block widths, distances between blocks and shear modulus. The initial separation loads and initial separation distances (lambda(cr), chi(cr)) between the homogeneous layer and the elastic semi-infinite plane were determined for continuous contact condition. The length of the separation zone was obtained for discontinuous contact condition. In addition to these, normal stress distributions between the layer and the semi-infinite plane were determined for continuous and discontinuous contact conditions. As a result of the study, the analytical results, and the results of the finite element method were shown by comparing as graphs and tables.
- MakaleYalnız künye2018EFFECTS OF STRAND CONFIGURATION ON PRE-TENSIONED I-GIRDERS
Atmaca, Barbaros; Ates, Sevket; Günaydin, Murat; Altunisik, Ahmet Can
The purpose of this paper is to examine the effect of strand configuration on the behavior of precast, pre-tensioned concrete I-girders by considering design load components for highway bridges as dead loads and equivalent lane loads. Under these loads, bridge girder's bottom flange is exposed to tensile stresses. To minimize or eliminate the tensile stresses, compressive stresses are induced in pre-stressed concrete with strands. Determination of strand configuration is important as well as number of strands because it affects stress distribution and displacement of bridge girders. One of the typical precast I-girder with 90 cm height is considered in this study. To determine strand configuration effects, eighteen I-girders with the same cross-section, effective span length and material properties but different strand configuration are selected as an application. Equal prestressing force is applied all strands simultaneously. Three dimensional finite element (FE) models of girder are constituted using ANSYS software. Result of beam theory is used to verify the modeling techniques. At the end of the study, numerically identified stress distribution and displacement for I-girders compared with each other. It is seen that proper strand configuration is effective to reducing stresses and displacements of pre-stressed I-girder.
- Derleme MakaleAçık Erişim2018A REVIEW OF FLOW BOILING IN MINI AND MICROCHANNEL FOR ENHANCED GEOMETRIES
Çebi, Alican; Celen, Ali; Donmez, Aydin Haci; Karakoyun, Yakup; Celen, Pinar; Cellek, Mehmet Salih; Dalkiliç, Ahmet Selim; Taner, Tolga; Wongwises, Somchai
Flow boiling researches in enhanced geometries practiced recently have been summarized in this review. Classical approximations in macroscale flows have not applied to the flows with small hydraulic diameters, so, this subject has been paid attention by the researchers. Application areas of these structures are increasing continuously due to cooling need in small confined spaces. The related studies have been reviewed in a chronological manner and their parameters have been given in a table in order for the researchers to observe the scientific duration regarding the progresses on this subject. Almost all papers on this subject have been produced after 2000, therefore, this subject is considered as an actual one to improve and worth to study in the literature. This study can not only be evaluated as the beginning argument for the researchers involved in flow boiling process in mini and microchannel, but it also consists of new works on the investigated subject.
- MakaleYalnız künye2017THE USABILITY OF VOLCANIC ROCKS FROM UPPER EUPHRATES PART IN THE EASTERN ANATOLIA REGION AS CONCRETE AGGREGATE
Aksüt, Yavuz Selim; Yetgin, Sukru
In this study; the engineering properties of volcanic rocks obtained from four different quarries in the province of Erzincan region in the Upper Euphrates Part in the Eastern Anatolia Region were investigated. In laboratory studies, the experiments including bulk and aggregate tests (bulk and dense unit weight, specific mass, water absorption, Los Angeles test for resistance to wear, freezing resistance and uniaxial compressive strength) were conducted on 5 volcanic samples according to the standards (Turkish Standard, British Standard and ASTM) and in the second stage, grading of concrete tests (grading of the concrete aggregates, concrete preparation, slump test, specific density of concrete, uniaxial compressive strength, modulus of elasticity, splitting tensile strength, abrasion resistance and capillarity) were performed on the concrete samples with volcanic aggregates. For fresh concrete composition, water/cement ratio was selected as the main variable providing homogeneous mixing and the highest strength to the concrete samples with a specific granulometry. Cylindrical concrete samples were produced with a variety of water/cement ratios cured for 7 and 28 days in water and their compressive strengths were assessed in the light of their physical and mechanical properties. The results obtained from aggregates and concrete tests, which were performed in line with the standards showed that especially Yassitepe-Dogu (YTD) sample, one of the volcanic rocks from Erzincan region can be used as concrete aggregate. It was observed that compressive strength of the concrete samples could satisfy C25/30 strength class and upper classes. In addition, it was understood that they can be used in highways, bridges, dams, buildings etc., especially as structural concrete.
- MakaleYalnız künye2015DYNAMIC DISPLACEMENT AND STRESS ANALYSES OF CANTILEVER RETAINING WALLS CONSIDERING SOIL-STRUCTURE INTERACTION AND WALL FLEXIBILITY
Çakir, Tufan; Dag, Serhat
The Mononobe-Okabe (M-O) method based on limit equilibrium principle is widely used in the design of retaining structures against earthquake loads. However, this method does not consider the soil-structure interaction and wave propagation effects. On the other hand, it is known that the interactions of retaining structures with backfill and foundation soils transform the seismic behavior of these structures to a rather complex problem. The main purpose of this study is to evaluate the soil-structure interaction and wall flexibility effects on the seismic behavior of backfill-cantilever retaining wall-foundation/soil systems. In line with this target, three dimensional finite element models were utilized for analyzing the aforementioned systems. Seismic analyses were carried out in the time domain by considering five different foundation soil conditions and two different wall thicknesses. The results were comparatively interpreted in terms of lateral wall displacements and the stresses occurring at critical sections of the wall. It was observed that these responses may vary significantly due to soil-structure interaction and wall flexibility effects.
- MakaleYalnız künye2015RESONANT VIBRATIONS OF TWO-SPAN RAILWAY BRIDGES UNDER HIGH-SPEED TRAINS
Kahya, Volkan; Araz, Onur; Turan, Muhittin
In this study, resonant vibrations of two-span railway bridges subjected to high-speed trains (HSTs) are studied. The continuous beam is modelled by using Bernoulli-Euler beam theory, and the train is considered as a series of moving concentrated loads. The dynamic response is obtained analytically by using the assumed mode method. Effects of the speed parameter and the span to car length ratio on the response are examined. Numerical results show that the above mentioned parameters play very important role on the dynamic behavior of two-span bridges.
- Derleme MakaleYalnız künye2015EXPERIMENTAL INVESTIGATION OF THE STRESS RELAXATION BEHAVIOURS OF EPDM SYNTHETIC RUBBERS
Mazlum, Ugur; Vahapoglu, Vahap; Karadeniz, Sami
Rubber type materials are preferred because they are suitable for use in many engineering applications besides their elasticity. EPDM rubber show outstanding heat, ozone and weather resistance and has excellent electrical properties. Therefore this rubber as an elastomer is an engineering material that has wide range of applications in industry such as door and window seals, radiator, garden and heating hoses, tubing, washers, belts, electrical insulation, roofing membrane and rubber mechanical goods. In this works, the stress relaxation behaviour of EPDM rubber at the room temperature were experimentally investigated. Applied to the hardness EPDM samples were subjected to different loading programs. In addition, for the loading programs that were implemented, it is shown that for the EPDM rubbers tested the stress relaxation curves obtained at different stretch ratios may be represented by a single representative curve for the specimens having the same hardnesses.
- DergiJOURNAL OF THERMAL ENGINEERING