Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
Browse
69 results
Search Results
Now showing 1 - 10 of 69
Article Citation - WoS: 2Citation - Scopus: 1Çelik Fiber Katkısının Farklı Boyuna Donatı Oranına Sahip Betonarme Döşemelerin Zımbalama Davranışı Üzerinde Etkileri(2019) Saatci, Selcuk; Yasayanlar, Suleyman; Yasayanlar, Yonca; Batarlar, BaturaySunulan çalışmada her iki yönde birbirine dik 0,004 (D1 serisi) ve 0,002 (D2 serisi) oranında boyuna donatıiçeren 2150x2150x150 mm boyutlarında iki grup betonarme döşeme, hacimce %0, %0,5, %1 ve %1,5oranında çelik fiber katkısı içeren beton karışımlarıyla dökülmüştür. Üretilen toplam sekiz döşeme ortanoktalarından statik yük altında test edilmişlerdir. Çelik fiber katkısı olmayan numunelerde yüksek boyunadonatı oranına sahip döşeme boyuna donatısında akma gerçekleşmeden gevrek bir şekilde zımbalamagöçmesi oluşurken düşük boyuna donatı oranına sahip döşeme zımbalama gerçekleşmeden önce çok dahasünek bir davranış göstermiştir. Çelik fiber katkısı her iki boyuna donatı oranında da iki kata varan oranlardazımbalama dayanımı artışlarına sebep olmuştur. Ancak D1 serisi döşemelerde çelik fiber katkısı maksimumyer değiştirmeleri önemli ölçüde arttırırken D2 serisinde maksimum yer değiştirmelerde önemli bir farkoluşmamış, bu döşemelerin yer değiştirmesi boyuna donatının akması tarafından kontrol edilmiştir. Çelikfiber katkısı oranının arttırılması D1 serisi döşemelerde dayanımın ve maksimum yer değiştirmelerinartmasına sebep olurken, D2 serisi döşemelerde %1'in üstü çelik fiber katkı oranları davranışta önemli birfark oluşturmamıştır. Yapılan deneyler Kritik Kesme Çatlağı Teorisi kullanılarak analitik olarakmodellenmiş ve bu tip modelleme ile ilgili bazı iyileştirmeler önerilmiştir.Article Citation - WoS: 7Citation - Scopus: 5Meteorological Drought and Trend Effects on Transboundary River Basins in Afghanistan(Springer, 2023) Hayat, Ehsanullah; Tayfur, GökmenAfghanistan, as a landlocked country located within central and southwestern Asia, has an arid to semi-arid climate. Most of the people are involved in agricultural activities, and a major part of the country's gross domestic product depends on agriculture, but the country has the lowest water storage capacity. Consecutive periods of drought and rapid snowmelt due to climate change have made it more challenging for suitable water resource management practices. This study investigates the historical meteorological drought characteristics across the whole country by employing the Reconnaissance Drought Index for the period 1979-2019 using data from 55 meteorological stations. Trends in precipitation and temperature are also investigated using the Mann-Kendall's and the Sen's slope statistical tests. A four-decadal countrywide drought map is generated. Extreme and severe droughts were observed in 1999 and 2000 across the whole country. Moderate drought events have started to occur with a frequency of 3 to 5 years since 1999. The decadal annual rainfall values in each river basin indicate that rainfall has decreased in the last two decades with a significant decline in 1999-2008. The trends of increase in temperature and decrease in precipitation are indications of rapid climate change in the country, especially in the south, west, and southwest regions. Due to the intensity and frequency of the droughts, river flow rates have decreased; and therefore, there is a need for the upstream and downstream neighboring countries to come to terms with the phenomenon of a new normal in the hydrological cycle and accordingly revise new water sharing treaties.Correction 3D modelling of surface spreading and underground dam groundwater recharge: Egri creek subbasin, Turkey(Springer, 2023) Şahin, Yavuz; Tayfur, GökmenArticle Citation - WoS: 15Citation - Scopus: 17Effects of Nanosecond Laser Ablation Parameters on Surface Modification of Carbon Fiber Reinforced Polymer Composites(SAGE Publications, 2023) Martin, Seçkin; İplikçi, Hande; Barışık, Murat; Türkdoğan, Ceren; Yeke, Melisa; Nuhoğlu, Kaan; Esenoğlu, Gözde; Tanoğlu, Metin; Aktaş, Engin; Dehneliler, Serkan; İriş, Mehmet ErdemRemoval of contaminants and top polymer layer from the surface of carbon-fiber-reinforced polymer (CFRP) composites is critical for high-quality adhesive-joining with direct bonding to the reinforcing fiber constituents. Surface treatment with a laser beam provides selective removal of the polymer matrix without damaging the fibers and increasing the wettability. However, inhomogeneous thermal properties of CFRP make control of laser ablation difficult as the laser energy absorbed by the carbon fibers is converted into heat and transmitted through the fiber structures during the laser operation. In this study, the effect of scanning speed and laser power on nanosecond laser surface treatment was characterized by scanning electron microscope images and wetting angle measurements. Low scanning speeds allowed laser energy to be conducted as thermal energy through the fibers, which resulted in less epoxy matrix removal and substantial thermal damage. Low laser power partially degraded the epoxy the surface while the high power damaged the carbon fibers. For the studied CFRP specimens consisting of unidirectional [45/0/?45/90]2s stacking of carbon/epoxy prepregs (HexPly®-M91), 100 mJ/mm2 generated by 10 m/s scanning speed and 30 W power appeared as optimum processing parameters for the complete removal of epoxy matrix from the top surface with mostly undamaged carbon fibers and super hydrophilic surface condition. © The Author(s) 2023.Article Citation - WoS: 4Citation - Scopus: 53d Modelling of Surface Spreading and Underground Dam Groundwater Recharge: Egri Creek Subbasin, Turkey(Springer, 2023) Şahin, Yavuz; Tayfur, GökmenThis study investigated surface spreading and underground dam recharge methods to replenish groundwater in Turkey's Egri Creek Sub-basin of the Kucuk Menderes River Basin. A three-dimensional numerical model was employed for this purpose. Field and lab data are provided to the model for realistic simulations. Pumping test results were used to determine the aquifer parameters. The laboratory works involved sieve analysis, permeability tests, and porosity and water content prediction. The numerical model's boundary conditions were determined from the geological and hydrogeological characteristics of the study area. Initial conditions were expressed regarding water content and pressure head in the vadose zone. The numerical model was satisfactorily validated by simulating water levels in three different pumping wells in the study area. Seven different scenarios, each having a different pool size, were investigated for the surface spreading recharge method. The results showed that a pool size of 30 x 30 m with a 6-m depth basin was the most optimal choice, raising the groundwater level to about 29.3 m. On the other hand, it was found that an underground dam could raise the levels by an average of 9.5 m, which might not be significant to warrant the construction.Article Citation - WoS: 2Citation - Scopus: 2Numerical Simulation of Flow and Dam Body Sediment Over a Movable Bed Due To an Earthfill Dam Break(Yıldız Teknik Üniversitesi, 2022) Tayfur, Gökmen; Issakhov, Alibek; Zhandaulet, YeldosThis paper presents the numerical simulations of flow and dam body sediment transport over a movable bed due to an earthfill dam break. The RANS equations, together with the k-omega SST turbulent model, are employed. The phase characteristic parameter is used as the phases of air, water, sediment, and bulk of dam body. The system of equations is solved numerically using the PISO algorithm. The numerical model is first verified using the dam break experimental data from the literature. The model successfully captures the temporal changes in the measured flow depths, pressures, wave fronts, and arrival times. The ve rified mod el is then app lied to simulate the flow and sediment transport as a result of an artificial earthfill dam break having an obstacle at its downstream section. The simulations show that there is a noticeable decrease in the shock pressures at all points around the obstacle and there is an increase in the water levels. The bulk dam body sediment moves together with the water flow wh ile sp reading. It takes longer time for the sediment laden flow to reach the obstacle. The investigation of dam body formed by different soils shows that the soil type has minor effect while the transport of sediment can raise the water levels and change the morphology of the downstream section.Article Citation - WoS: 2Citation - Scopus: 2Assessment of Future Water Demand in a Semiarid Region of Turkey: a Case Study of Tahtali–seferihisar Basin(Springer, 2023) Karahan, S. M.; Elçi, ŞebnemWater is a vital resource for society and nature, and its scarcity has consequences in all aspects of existence. Today, issues including the inability to preserve the status of existing water resources and excessive water withdrawal are causing the amount of water to diminish day by day. Furthermore, factors such as urbanization and industrialization, population growth, water quality degradation owing to agricultural pesticides, and climate change, all have a negative impact on water supplies. A basin-based water management analysis was carried out in this study by applying the "Integrated Water Resources Management" strategy to the Tahtalı–Seferihisar sub-basin in Turkey, where water stress is expected in the future. Using the WEAP (Water Evaluation and Planning System) model, the hydrological (precipitation, flow, evaporation) data of important water resources for the basin and Izmir (Tahtalı, Seferihisar, Ürkmez, and Kavakdere Dams) were used to predict the availability of water resources in the future, and several possible scenarios for water demands/supplies were analyzed. The water budget balances projected in 2050 have been calculated by considering six different scenarios: Reference Scenario, Report Consumption Scenario, Optimistic Case Scenario, Pessimistic Case Scenario, Return Flow Scenario, and Various Forecast Scenario. The water balances that can be obtained in each scenario under various situations were computed and compared. For all considered scenarios, unmet water demand in the basin is found to be significant (157.52 hm3 in the Optimistic Case Scenario and 373.16 hm3 in the Pessimistic Case Scenario).Article Citation - WoS: 8Citation - Scopus: 8Improving Adhesive Behavior of Fiber Reinforced Composites by Incorporating Electrospun Polyamide-6,6 Nanofibers in Joining Region(SAGE Publications, 2022) Esenoğlu, Gözde; Barışık, Murat; Tanoğlu, Metin; Yeke, Melisa; Türkdoğan, Ceren; İplikçi, Hande; Martin, Seçkin; Nuhoğlu, Kaan; Aktaş, Engin; Dehneliler, Serkan; İriş, Mehmet ErdemAdhesive joining of fiber reinforced polymer (CFRP) composite components is demanded in various industrial applications. However, the joining locations frequently suffer from adhesive bond failure between adhesive and adherent. The aim of the present study is improving bonding behavior of adhesive joints by electrospun nanofiber coatings on the prepreg surfaces that have been used for composite manufacturing. Secondary bonding of woven and unidirectional CFRP parts was selected since this configuration is preferred commonly in aerospace practices. The optimum nanofiber coating with a low average fiber diameter and areal weight density is succeed by studying various solution concentrations and spinning durations of the polyamide-6.6 (PA 66) electrospinning. We obtained homogeneous and beadles nanofiber productions. As a result, an average diameter of 36.50 +/- 12 nm electrospun nanofibers were obtained and coated onto the prepreg surfaces. Prepreg systems with/without PA 66 nanofibers were hot pressed to fabricate the CFRP composite laminates. The single-lap shear test coupons were prepared from the fabricated laminates to examine the effects of PA 66 nanofibers on the mechanical properties of the joint region of the composites. The single-lap shear test results showed that the bonding strength is improved by about 40% with minimal adhesive use due to the presence of the electrospun nanofibers within the joint region. The optical and SEM images of fractured surfaces showed that nanofiber-coated joints exhibited a coherent failure while the bare surfaces underwent adhesive failure. The PA66 nanofibers created better coupling between the adhesive and the composite surface by increasing the surface area and roughness. As a result, electrospun nanofibers turned adhesive failure into cohesive and enhanced the adhesion performance composite joints substantially.Article Citation - WoS: 1Citation - Scopus: 1Fragility Analysis of Wide-Beam Infill-Joist Block Rc Frames(Gazi Üniversitesi, 2022) Dönmez, Cemalettin; Karaarslan, Enes; Erberik, Murat AltuğPurpose: The purpose of the presented study is to develop fragility curves for the wide-beam infill-joist block reinforced concrete structures. Theory and Methods: Nonlinear time history analyses are performed for the set of selected ground motions. The performance levels are identified through pushover analysis and fragility curves are produced for ground motion parameters. Results: Fragility curves obtained for the wide-beam RC frames presents a different characteristic than the curves obtained for the conventional frames. Conclusion: Results show that wide-beam RC frame buildings are seismically more vulnerable than the conventional deep beam RC frame buildings based on structural models with similar properties. The possible reason seems to be low lateral stiffness of wide-beam frames that causes large lateral drift demands and therefore severe damage at the wide-beam column connections.Article Closure To "reverse Flood Routing in Rivers Using Linear and Nonlinear Muskingum Models" by Meisam Badfar, Reza Barati, Emrah Dogan, and Gokmen Tayfur(American Society of Civil Engineers (ASCE), 2022) Badfar, Meisam; Barati, Reza; Doğan, Emrah; Tayfur, Gökmen