WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Citation - WoS: 3Salihli Granitoid, Menderes Massif, Western Anatolia: a Sustainable Clean Energy Source for Mitigating Co2 Emissions(2022) Chandrasekharam, Dornadula; Ayzit, Tolga; Baba, AlperTurkey has a great opportunity to promote renewable energy, which is produced from high heat-generating granitoids using EGS (Enhanced Geothermal Systems) technology. Exploiting the energy from the radiogenic granitoid will help the country save about 32211 million kg of CO2 from gas-based electricity power plants. In addition to the hydrothermal energy sources, energy from EGS will make the country free from energy deficit and provide sustainable power, water, and food. In the present paper, we assess the power generation capacity of Salihli granitoid (SG), with an outcropping area of about 100 km2 located within the western Anatolian plateau, and describe the technology involved in harnessing the heat from these granitoids. The Anatolian Plateau is known for extension tectonics and is explained by the westward tectonic escape and subduction rollback processes. The most prominent structures of western Anatolia are E-W and ENE-WSW trending graben and horst controlled by low and high-angle oblique to dip-slip normal faults, exposing the Menderes Massif. Magmatic activity in western Anatolia is mainly related to episodic-two stage extensional regime, where the early phase is characterized mainly by calc-alkaline Early-Middle Miocene felsic lavas and pyroclastic and the latter by late Miocene-Quaternary rift-related alkaline basaltic volcanism. The plutonic activity started during 12 to 15 Ma represented by SG. The heat generation capacity of the SG varies from 5.5 to 6.7 (µW/m3), while the heat flow values over SG range from 68 to 107 HF (mW/m2). These values are much higher compared to the global average crustal values.Conference Object Citation - Scopus: 3Seismic Performance of Cfrp Jacketed Sub-Standard Rc Columns Under High Axial Stress and Shear Demand(Springer, 2022) Demir, Merve Nur; Demir, Uğur; Demir, Cem; İlki, AlperIn the last decades, lessons learnt from the major earthquakes, that occurred in many countries, brought revisions in prevailing seismic design codes. As a consequence of this phenomenon, the current building stock in Turkey is mainly comprised of reinforced concrete (RC) buildings which were designed according to different seismic design codes. The presented paper is a component of a comprehensive investigation which containing three variables i) high axial load ratio defined as axial load divided by the axial capacity, ii) high shear demand defined as the ratio of shear demand at flexural yielding to shear resistance and iii) low transverse reinforcement ratio owing to large spacing among steel reinforcements. Thus, a total of four full-scale square RC columns comprised of i) one column designed to comply with the former Turkish Seismic Design Code (TSDC, 1975) and ii) three columns which are not compliant to any design codes (referred as sub-standard), were tested under high axial load ratio, 0.4 for code-conforming and 0.75 for sub-standard columns, combined with reversed cyclic lateral loading. The columns were also designed to have high shear demand in the order of 0.62 and 0.80 for bare sub-standard according to ACI 318 (2019) and TBEC (2018) design codes as sometimes observed in existing sub-standard structures. In addition to that, the ratio of shear demand for the code-conforming column is calculated 0.43 and 0.50 as per design codes, respectively. Besides, the ratio of transverse reinforcement area to the minimum required transverse reinforcement area was 0.19 and 0.77 for sub-standard columns according to ACI 318 (2019) and TBEC (2018), respectively. For the code-conforming column, the aforementioned ratio was 0.57 and 1.32 for both design codes, in the same manner. One of the sub-standard columns was kept as a reference column while the other two of them have been externally jacketed with one layer or two layers of carbon fiber-reinforced polymer (CFRP) sheets. Test results pointed out that the confinement provided by CFRP jacketing has remarkably improved the performance of seismically-deficient RC columns subjected to high axial compression under high shear demand in terms of lateral load capacity and ductility. The experimental results were also supplemented with theoretical work to evaluate the effects of CFRP jacketing on the seismic behavior of sub-standard RC columns.Conference Object Citation - WoS: 1Citation - Scopus: 2Seismic Performance of Substandard Rc Columns Retrofitted With Sprayed Gfrm(Springer, 2022) Kian, Nima; Demir, Uğur; Demir, Cem; Maraşlı, Muhammed; İlki, AlperThere is a myriad amount of substandard reinforced concrete (RC) buildings in developing countries that do not comply with the requirements and instructions of the current building design codes. In particular, columns in these substandard buildings demonstrate unsatisfactory and undesired behavior against lateral loads, mainly due to low concrete compressive strength and poor reinforcement detailing. The problem is exacerbated when the axial load ratio (ratio of applied axial load to the axial load capacity) and/or the shear ratio (ratio of shear force corresponding to moment capacity (Ve) to the shear capacity (Vr)) is/are high, leading to brittle failure modes. In this study, three full-scale substandard RC columns subjected to high axial load ratio of 0.75 were tested under constant axial load combined with reversed cyclic lateral displacements. Shear ratio (Ve/Vr) of the substandard columns were 0.75 and 0.82 according to ACI 318-19 (ACI 318 (2019) Building Code Requirements for Structural Concrete. American Concrete Institute, Farmington Hills, MI, USA) and (Turkish Building Earthquake Code (Turkish Building Earthquake Code (TBEC) (2018) Disaster & Emergency Management Authority, Ankara, Turkey), respectively. According to the TBEC (Turkish Building Earthquake Code (TBEC) (2018) Disaster & Emergency Management Authority, Ankara, Turkey), columns had a high Ve/(fctmbd) ratio of 1.12, where, fctm, b, and d are the direct tensile strength of concrete, width of the cross-section, and effective depth of the section. The ratio of transverse reinforcement to minimum required transverse reinforcement according to the ACI 318-19 (ACI 318 (2019) Building Code Requirements for Structural Concrete. American Concrete Institute, Farmington Hills, MI, USA) and TBEC (Turkish Building Earthquake Code (TBEC) (2018) Disaster & Emergency Management Authority, Ankara, Turkey) was 0.19 and 0.77, respectively. Two of the columns were retrofitted with an innovative, cost-effective, and easily-applicable strengthening method, through external jacketing with sprayed glass fiber reinforced mortar (GFRM) of different characteristics. The remaining column was tested as the reference specimen to evaluate the efficiency of the strengthening method. The test results demonstrated the extremely poor performance of the reference substandard column as well as the remarkable lateral load capacity and ductility improvement provided by the adopted novel strengthening approach.Article Citation - WoS: 1Artificial Neutral Networks To Predict Design Properties for Cemented Embankment Layers of High Speed Train Rail Ways(Foundation Cement, Lime, Concrete, 2013) Egeli, İsfendiyar; Tayfur, Gökmen; Yılmaz, E.; Uşun, HandanI. EGELI, G. TAYFUR, E. YILMAZ, H. USUN ARTIFICIAL NEURAL NETWORKS TO PREDICT DESIGN PROPERTIES FOR CEMENTED EMBANKMENT LAYERS OF HIGH SPEED TRAIN RAILWAYS Cement-Wapno-Beton, Vol. XVIII/LXXX, 2013, No 1, p. 10 High-speed train railway (HSTR) embankment is a complicated process, as it deals with high geometric design standards and material properties. In this study the replaceability of fill strata without cement prepared subgrade layer and with cement addition one is investigated. In the experiments the specimens composed of natural sand with different cement additions and two w/c ratios were used. The Plaxis-FEM (2D) program was employed to find the maximum expected total settlements of HSTR embankments with cemented subgrade layer. Furthermore, the artificial neural networks model was constructed to predict the failure stress, elasticity modulus and strains. The sensivity analysis has revealed that cement content was the most sensitive for stress and elasticity modulus predictions, while the curing age of specimens was for the strain forecast.Article Citation - WoS: 11Citation - Scopus: 12A Novel Transformable Structural Mechanism for Doubly Ruled Hypar Surfaces(The American Society of Mechanical Engineers(ASME), 2015) Maden, Feray; Aktaş, Engin; Korkmaz, KorayA novel structural mechanism (SM) that is capable of transforming itself into various hyperbolic paraboloid (hypar) geometries is introduced in this paper. Composed of straight bars and novel joint types, the SM is designed based on the ruled surface generation method. Thus, the paper first investigates the geometrical properties and morphology of the hypar surface. Second, it constructs the SM and discusses its transformation capability with respect to its kinematic properties. Then, it presents a parametric model not only to analyze the geometry and possible configurations of the SM but also to prepare a model for the structural analysis. Finally, a transformable shelter structure is proposed as an architectural application of the SM and its feasibility is tested based on the structural analysis conducted in different configurations of the structure. According to the results of the structural analysis, the strength, and the stiffness of the structure are discussed in detail.Article Citation - WoS: 13Citation - Scopus: 14Soil Erosion Model Tested on Experimental Data of a Laboratory Flume With a Pre-Existing Rill(Elsevier Ltd., 2020) Aksoy, Hafzullah; Gedikli, Abdullah; Yılmaz, Murat; Eriş, Ebru; Ünal, N. Erdem; Yoon, Jaeyoung; Tayfur, GökmenPrediction of sediment discharge transported within flow is strongly needed in order to provide measures for a well-established erosion control and water quality management practice. Initiated by runoff generation and erosion processes sediment transport is influenced by microtopography over hillslopes of hydrological watersheds. Consideration of microtopography provides more accurate results. In this study, a process-based two-dimensional rainfall-runoff mathematical model is coupled with erosion and sediment transport component. Both the rainfall-runoff and sediment transport components make simulations in rills and over interrill areas of a bare hillslope. Models at such fine resolution are rarely verified due to the complexity of rills and interrill areas. The model was applied on a data set compiled from laboratory experiments. Erosion flume was filled with granular sand to replace a bare soil. A longitudinal rill and an interrill area were pre-formed over the soil in the flume before the simulated rainfall exerted on. The flume was given both longitudinal and lateral slopes. The simulated rainfall was changed between 45 mm/h and 105 mm/h and exerted on granular uniform fine and medium sand in the erosion flume with longitudinal and lateral slopes both changing from 5% to 20%. Calibration of the model shows that it is able to produce good results in terms of sedigraphs, which suggest also that the model might be considered an important step to verify and improve watershed scale erosion and sediment transport models.Article Citation - WoS: 20Citation - Scopus: 25Experimental Investigation on Reinforced Concrete Slabs Strengthened With Carbon Textiles Under Repeated Impact Loads(John Wiley and Sons Inc., 2020) Batarlar, Baturay; Hering, M.; Bracklow, F.; Kühn, T.; Beckmann, B.; Curbach, M.This study presents the performance of carbon textile reinforcement used as strengthening layers for reinforced concrete (RC) slabs under repeated impact loads. In order to reveal the contribution of carbon textile reinforcement to the behavior of RC slabs under impacts, five identical RC slabs with the dimensions of 1.5 m × 1.5 m × 0.20 m were manufactured and tested at the Technische Universität Dresden. To understand failure mechanisms of RC slabs under impact loadings, two specimens were kept unstrengthened and tested under different impact velocities. The rest of the specimens was strengthened with three different carbon textile reinforcements embedded in an additional 2 cm fine-grained concrete layer and subjected to impact loads with the same striker velocity. The results observed from the tests revealed that the carbon textile reinforcement is very effective at increasing the impact capacities of the specimens. Additionally, displacement–time histories and crack profiles are highly affected due to the carbon textile reinforcement types and ratios during the impact loadings. © 2020 The Authors. Structural Concrete published by John Wiley & Sons Ltd on behalf of International Federation for Structural Concrete.Conference Object A Boundary Element Method for Axisymmetric Elastodynamic Analysis(John Wiley and Sons Inc., 1996) Özkan, Gonca; Mengi, YalçınA new numerical method is proposed for the boundary element analysis of axisymmetric bodies. The method is based on complex Fourier series expansion of boundary quantities in circumferential direction, which reduced the boundary element equation to an integral equation in (r-z) plane involving the Fourier coefficients of boundary quantities, where r and z are the coordinates of the r theta z cylindrical coordinate system. The kernels appearing in these integral equations can be computed effectively by discrete Fourier transform formulas together with the fast Fourier transform (FFT) algorithm, and the integral equations (r-z) plane can be solved by Gaussian quadrature, which establishes the Fourier coefficients associated with boundary quantities. The Fourier transform solution can then be inverted into r theta z space by using again discrete Fourier transform formulas together with FFT algorithm. In this paper, we present the formulation of the proposed method which is outlined above. A comparison is given between the existent methods in literature and our method, which shows that the use of FFT algorithm for the integrations in circumferential direction provides considerable saving in computer time.Conference Object Upscaling Surface Flow Equations Depending Upon Data Availability at Different Scales(Springer Verlag, 2003) Tayfur, GökmenSt. Venant equations, which are used to model sheet flows, are point-scale, depth-averaged equations, requiring data on model parameters at a very fine scale. When data are available at the scale of a hillslope transect, the point equations need to be upscaled to conserve the mass and momentum at that scale, Hillslope-scale upscaled model must be developed if data are available at that scale. The performance of the three models applied to simulate flows from non-rilled surfaces revealed that the hillslope-scale upscaled model performs as good as the point-scale model though it uses far less data. The transectionally-upscaled model slightly underestimates the observed data.Conference Object Citation - WoS: 1Effect of Water Source on Human Health: a Case Study From Biga Peninsula, Turkey(2009) Baba, Alper; Gündüz, OrhanThe concentrations of certain elements including arsenic (As), fluoride (F) and aluminum (AI) were measured in groundwater in the different part of Biga Peninsula which is located in the western parts of Turkey. The concentration values of As and AI in groundwater ranged between 10-40 ppb, 0.5-0.8 ppm and 1-11.5 ppm, respectively, in this region. Al values exceed the Turkish drinking water standard value of 0.2 ppm. Furthermore, As concentration in water from alteration zones exceed the drinking water standard value of 10 ppb. Based on this background, this study was intended to investigate the source of these heavy metals and its neurotoxin effects on human health as many people living in this region have undergone medical treatment, which are believed to be related to the quality of water resources originating from densely altered volcanic rocks.