Civil Engineering / İnşaat Mühendisliği

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Çelik Fiber Katkısının Farklı Boyuna Donatı Oranına Sahip Betonarme Döşemelerin Zımbalama Davranışı Üzerinde Etkileri
    (2019) Saatci, Selcuk; Yasayanlar, Suleyman; Yasayanlar, Yonca; Batarlar, Baturay
    Sunulan 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: 8
    Citation - Scopus: 9
    Çelik Fiber Katkılı Etriyesiz Betonarme Kirişlerin Davranışı
    (Gazi Üniversitesi, 2017) Saatçi, Selçuk; Batarlar, Baturay
    Sunulan çalışmada çelik fiber katkısının farklı boyuna donatı oranlarına sahip etriyesiz betonarme kirişlerineğilme davranışına olan etkileri deneysel ve analitik olarak incelenmiştir. Yapılan deneysel çalışmada düşükve yüksek boyuna donatı oranına sahip iki grup kiriş imal edilmiştir. Her bir gruptaki kirişlerhacimce %0, %0,5, %1,0 ve %1,5 çelik fiber oranına sahip olup toplam sekiz kiriş açıklık ortasına uygulananyük altında test edilmiştir. Düşük boyuna donatı oranına sahip kirişlerde çelik fiber katkısı eğilme kapasitesini %50'ye yakın oranlarda arttırmış, ancak deformasyonların tek bir çatlakta toplanması sebebiyleboyuna donatıda kopmaya yol açarak çelik fiber katkısız kirişe göre daha az yerdeğiştirme yapmasına sebepolmuştur. Yüksek boyuna donatı oranına sahip kirişlerde ise çelik fiber katkısı etriye görevi görerek çelikfiber katkısı olmaması durumunda gevrek eğik çekme göçmesi gösteren kirişlerin sünek eğilme göçmesigöstermelerini sağlamıştır. Her iki grupta çelik fiber oranının arttırılması çatlak dağılımını etkilemeklebirlikte davranışta önemli bir farklılığa yol açmamıştır. Kirişler analitik yöntemlerle modellendiğindeliteratürde yaygın kullanılan ve çatlakta çelik fiberlerin taşıdığı çekme gerilmesini sabit kabul edenyaklaşımın güvenli tarafta olmakla birlikte eğilme kapasitesinin olduğundan düşük hesaplanmasına yolaçtığı, çekme gerilmelerini çatlak genişliği ile ilişkilendiren daha hassas modellerin daha iyi sonuçverebilecekleri görülmüştür
  • Book
    Citation - Scopus: 6
    Climate Change and Its Effects on Water Resources: Issues of National and Global Security
    (Springer, 2011) Baba, Alper; Gündüz, Orhan; Friedel, Michael J.; Tayfur, Gökmen; Howard, Ken W.F.; Chambel, Antonio
    National and global security can be assessed in many ways but one underlying factor for all humanity is to access to reliable sources of water for drinking, sanitation, food production and manufacturing industry. In many parts of the world, population growth and an escalating demand for water already threaten the sustainable management of available water supplies. Global warming, climate change and sea level rise are expected to intensify the resource sustainability issue in many water-stressed regions of the world by reducing the annual supply of renewable fresh water and promoting the intrusion of saline water into aquifers along sea coasts where 50% of the global population reside. Pro-active resource management decisions are required, but such efforts would be futile unless reliable predictions can be made to assess the impact of the changing global conditions that would impart upon the water cycle and the quality and availability of critical water reserves.
  • Article
    Citation - Scopus: 4
    Betonarme Çerçeve Yapıların Olasılıklı Sismik Analizi
    (Gazi Üniversitesi, 2006) Korkmaz, Armağan; Aktaş, Engin
    Betonarme çerçeve yapıların sismik davranışlarının belirlenmesinde, analizlere olasılıklı ifadelerin dahil edilmesi, sismik davranışın daha gerçekçi tanımlanmasına yardımıcı olacaktır. Çalışmada betonarme çerçeve yapıların olasılıklı sismik analizlerinin gerçekleştirilmesi amaçlanmış, bu amaçla örnek betonarme çerçeve yapılar ele alınmıştır. Bu betonarme çerçeve yapılar için öteleme analizleri DRAIN 2D programı ile yapılmıştır. Öteleme analizlerinin ardından zaman tanım alanında dinamik analizler gerçekleştirilmiştir. Öteleme analizleri, zaman tanım alanında dinamik analiz sonuçları ile karşılaştırılmıştır. Bu karşılaştırmanın ardından kırılganlık analizleri yapılmıştır. Betonarme çerçeve yapıların olasılıklı sismik davranışını ortaya koymak amacı ile kırılganlık analizleri ile kırılganlık eğrileri elde edilmiştir. Çalışmanın ana amacı, öteleme analizleri ile zaman tanım alanında dinamik analizlerin karşılaştırılması sonucu, daha gerçekçi bir sismik davranış tanımlama ihtiyacının olduğunu göstermek ve kırılganlık analizleri ile, sismik davranışın olasılıklı olarak daha gerçekçi bir şekilde ifadesini sağlayabilmektir.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 5
    Dynamic Analysis of an Immersed Tunnel in Izmir;
    (Pontificia Universidad Catolica de Chile, Escuela de Construccion Civil, 2018) Egeli,I.; Gurbuz,C.
    The original design of the planned Izmir Bay Immersed Tube Tunnel, considered it to be a continuous subsea tunnel for the whole length of about 7.6 km. But this was later changed into having 2 shorter tubes of 2.7 km long each connected thru’ a 2.2 km long artificial island created in the middle of the bay from the excess dredged material, a concept which also reduces costs and increases efficiency. This island will serve as a venue for the 2025 Expo Exhibition, which Izmir city will apply to organize in the future. Reason for the research study was to provide a preliminary design, using a dynamic analysis, during the current pre-feasibility stage, of the immersed tunnel to show whether it can be built across the Izmir Bay. This paper takes into account the new alignment and presents the results of a 2-D dynamic analysis conducted of the prefabricated 100m long tunnel elements, sitting within a backfilled dredged ditch, dug after the recommended ground improvement was carried out. Analyses considered staged construction and the results showed that: Tunnel units and its surrounding soils inside the dredged ditch act together to provide a better earthquake response with a damping effect of the earthquake force; Tunnel units do not float to the sea surface, but continued to stay inside the dredged ditch and applied positive stresses to the foundations during the design earthquakes. As there was no floating, there was no need for anchoring the tunnel to ditch bottom; Tunnel units and immersion joints (made of specified strong elastomer material) continued to stay in compression longitudinally and provided a superb water-tightness level; There were no risky (un-tolerable) ground deformations during, after striking of the design earthquakes. Total vertical and differential displacements of the tunnel units and in the surrounding soils were all at acceptable levels; Concrete surface crack widths occurring in the tunnel units, during striking of the design earthquakes were also found to be allowable. Study results show that the tunnel elements can withstand Mw=7 short duration (<10 sec) or Mw=6 long duration (>10 sec) earthquakes without major damages to their structure © 2018. Revista de la Construccion. All rights reserved.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 24
    Developing Polymer Composite-Based Leaf Spring Systems for Automotive Industry
    (Walter de Gruyter GmbH, 2018) Öztoprak, Nahit; Güneş, Mehmet Deniz; Tanoğlu, Metin; Aktaş, Engin; Eğilmez, Oğuz Özgür; Şenocak, Çiler; Kulaç, Gediz
    Composite-based mono-leaf spring systems were designed and manufactured to replace existing mono-leaf metal leaf spring in a light commercial vehicle. In this study, experimentally obtained mechanical properties of different fiber-reinforced polymer materials are presented first, followed by the description of the finite element analytical model created in Abaqus 6.12-1 (Dassault Systemes Simulia Corp., RI, US) using the obtained properties. The results from the finite element analysis are presented next and compared with actual size experimental tests conducted on manufactured prototypes. The results demonstrated that the reinforcement type and orientation dramatically influenced the spring rate. The prototypes showed significant weight reduction of about 80% with improved mechanical properties. The hybrid composite systems can be utilized for composite-based leaf springs with considerable mechanical performance.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Çelik Fiber Katkısının Farklı Boyuna Donatı Oranına Sahip Betonarme Döşemelerin Zımbalama Davranışı Üzerinde Etkileri
    (Gazi Üniversitesi, 2019) Saatçi, Selçuk; Yaşayanlar, Süleyman; Yaşayanlar, Yonca; Batarlar, Baturay
    In this study, reinforced concrete slabs in two groups, having 0.004 (D1 series) and 0.002 (D2 series) longitudinal reinforcement ratios in two orthogonal directions, were cast with concrete mixes containing 0%, 0.5%, 1% and 1.5% steel fiber ratios in volume. Slabs were 2150x2150x150 mm in dimensions. Eight slabs were tested in total under static loads. For slabs without steel fibers, the slab with higher reinforcement ratio showed punching failure before the yielding of longitudinal bars, whereas the slab with lower reinforcement ratio displayed a significantly higher ductility before final punching failure. Addition of steel fibers increased the punching load capacity up to two times. However, although addition of steel fibers also increased the maximum displacements in D1 series slabs, it did not make any significant effect on the maximum displacements of D2 series slabs. Maximum displacements were still controlled by the yielding of longitudinal reinforcement. Increasing the steel fiber ratio increased both the punching capacity and the maximum displacements in D1 series slabs, but it did not make a significant difference in behavior of D2 series beyond 1% fiber ratio. An analytical study of the test specimens were also performed using Critical Shear Crack Theory and based on comparisons of experimental and analytical results some improvements in the model were proposed. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Determining Water and Sediment Quality Related To Lead-Zinc Mining Activity
    (Polish Academy of Sciences, 2018) Şanlıyüksel Yücel, Deniz; Baba, Alper
    This study focuses on the Koru and Tesbihdere Pb-Zn mining districts, located at the upstream areas of the Umurbey dam basin. Mining activities in Koru, one of the longest operated mines in NW Turkey, date back to the beginning of the 1900s. The purpose of the study is to (1) determine the hydrochemical properties of the water resources and to assess the potential environmental consequences of mining activities in the Koru and Tesbihdere mining districts, and (2) investigate the effects caused by mining activities on the water resources and sediment quality in the Umurbey dam basin. Concentrations of As, Cd, Cu, Fe, Mn, Pb, and Zn in river sediments downstream of the Tesbihdere and Koru mining district, and in the Umurbey dam sediments were higher than the world average for river sediments. The geoaccumulation index and enrichment factor revealed that sediments were strongly polluted with Pb and Zn, moderately to strongly polluted with Cd and moderately polluted with Cu. The chemical analyses of water resources revealed that the maximum Fe, Zn, Pb, Mn, and Cu concentrations reached 2890 μg/l, 1785 μg/l, 1180 μg/l, 984 μg/l, and 419 μg/l, respectively. The Koru River is classified as polluted water according to Turkish inland water quality regulations. The environmental contamination problems in the local drainage system are caused by leakage from past and current tailing ponds into the Koru River.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 2
    Climate Change Mitigation With Renewable Energy: Geothermal
    (Springer Verlag, 2011) Baba, Alper
    On a global scale, there is increasing evidence that climate is changing and of a discernible human influence. Many of scientists are confident that if current emissions of greenhouse gases continue, the world will be warmer, sea levels will rise and regional climate patterns will change. According to some scientist, global temperatures are expected to rise faster over the next century than over any time during the last 10,000 years. From this token, geothermal energy is now considered to be one of the most important alternative energy sources to minimize climate change. Geothermal technologies for power generation or direct use operate with little or no greenhouse gas emissions. Geothermal energy is generally accepted as being an environmentally-friendly energy source, particularly when compared to fossil fuel energy sources. Geothermal resources have long been used for direct heat extraction for district urban heating, industrial processing, domestic water and space heating, leisure and balneotherapy applications. Geothermal energy is used in more than 80 countries for direct heat application and 24 countries for power generation. Re-injection of fluids maintains a constant pressure in the reservoir, thus increasing the field's life and reducing concerns about environmental impacts. Geothermal energy has several significant characteristics that make it suitable for climate change mitigation.
  • Article
    Modeling Water Stress Effect on Soil Salinity
    (Springer Verlag, 2011) Tayfur, Gökmen
    As it is widely known the earth is experiencing a climate change. The primary effect of this change is the increase trend in global temperature. This, in turn, results in increased number of events in flooding, and drought in different parts of the world. A secondary effect is the change in water and soil salinity. A considerable portion of the cultivated land in the world is affected by salinity, limiting productivity potential. About 20 million ha of total 230 million ha of irrigated land in the world are salt affected. The climate change is expected to worsen this situation. This study explores the water stress effect on soil salinity. For this purpose, a model is developed to simulate salt transport in a layered soil column. The soil salinity transport model development involves two parts: (1) modeling salt movement through sail layers due to runoff, percolation, and lateral subsurface flow, and (2) modeling dissolution and precipitation of gypsum which acts as sink or source for salts in soil. The model is calibrated and validated with measured data. The soil is irrigated under optimal and water stress irrigation conditions. The major model parameters affecting the soil salinity are found to be wilting point, field capacity, hydraulic conductivity, initial soil salinity, and soil gypsum concentration. The results have revealed that water stress results in high concentration of salt accumulation in soil columns.