Civil Engineering / İnşaat Mühendisliği
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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 - Scopus: 2Application of Endurance Time Method in Seismic Assessment of Rc Frames Designed by Direct Displacement-Based Procedure(Turkish Chamber of Civil Engineers, 2024) Karımzada, Nisar Ahmad; Shırkhanı, Amir; Aktaş, EnginThis paper addresses the Direct Displacement-Based Design (DDBD) approach of multi-story RC frame structures consistent with changes to design criteria between Turkish earthquake codes of TSC-2007 and TBEC-2018. The corresponding response modification factor (R) of structures designed based on the DDBD approach is also estimated in this research. The design base shear forces of both codes are compared considering different R factors and also with that of the DDBD approach. The results showed that the DDBD approach, as per TBEC-2018, provides RC frame structures with higher R values compared to the similar approach in accordance with TSC-2007. The Endurance Time (ET) method is a time history-based procedure for seismic assessment of structures under intensifying dynamic excitations aided to judge their performance at various intensity levels. Since, up to now, the ET method has not been considered to evaluate the performance of the structures designed by the DDBD approach, this paper addresses this issue. The ET performance curves of RC frames show that structures designed by the DDBD approach in accordance with TBEC-2018 exhibit higher Interstory Drift Ratios (IDRs) values than TSC-2007 at various hazard levels.Article Citation - Scopus: 3A Brief Overview on Geothermal Scaling(General Directorate of Mineral Research and Exploration (MTA), 2023) Isık, Tuğba; Baba, Alper; Chandrasekharam, Dornadula; Demir, Mustafa M.; Isık, Tuğba; Baba, Alper; Demir, Mustafa MuammerHot spring waters are rich in terms of minerals. Since there are dramatic changes in thermodynamic parameters in geothermal power plants, such as a decrease in temperature and pressure, severe precipitation occurs throughout the system components in an uncontrolled manner. There are three main chemistries in deposits: carbonates (mainly calcium carbonates), silicates (metal silicates), and sulphides (antimony sulphide-stibnite). Energy harvesting is remarkably reduced out of the insulating nature of the deposit. Various actions need to be taken to mitigate this undesirable issue of scaling in geothermal systems. Geothermal systems are in fact quite complex, and the composition of brine and, accordingly, the chemistry of the deposit are not identical. Therefore, each system should be studied individually, and a tailor-made remedy should be developed. In this overview, the types of deposits in terms of chemistry and the actions (pH modification or antiscalant dosing) that should be taken to reduce scaling are mentioned, and potential chemistries of antiscalants are given.Article Citation - WoS: 1Citation - Scopus: 2Geothermal Power Corridor-Connecting the Middle East Countries(Maden Tetkik ve Arama Genel Mudurlugu-mta, 2023) Chandrasekharam, DornadulaThe Middle East economy and life depend on imports, be it food, water, or energy, despite each country in the region having enormous energy resources to exploit and reduce dependency on countries outside the region and develop a socioeconomic model of regional cooperation and synergy. An estimated 371 TWh of electricity available from geothermal energy resources can be utilized by these countries to support basic needs and be free from food-energy-water imports by sharing their energy resources. The total amount of CO2 emissions from these countries is currently 945 x 106 kg, so these countries can further earn about 92 million euros from carbon savings, by using geothermal energy along this corridor. This amount can be utilized for augmenting the energy supply from geothermal sources. In this work, the available geothermal resources are evaluated, and suggestions are made how this energy can be best utilized for peaceful existence and cooperation in the region.Article Citation - WoS: 2Citation - Scopus: 2Effects of Mix-Design Variables on the Workability, Rheology and Stability of Self-Consolidating Concrete(Pontificia Universidad Catolica de Chile, Escuela de Construccion Civil, 2022) Alami, Mohammad Musa; Erdem, T.K.This study investigates the effects of basic mix design variables such as water/cement ratio (w/c), slump flow, coarse-to-total aggregate ratio (CA/TA), and maximum aggregate size (Dmax) on the main characteristics of self-consoli-dating concrete. The w/c of the mixtures was either 0.42 or 0.50. The CA/TA ranged between 0.45 and 0.53. Slump flow was adjusted to 550, 650 or 720 ±20 mm by varying the superplasticizer content. Dmax was varied as 10, 15 and 20 mm. V-funnel, L-box, rheometer, sieve segregation tests and a new test method, recently developed by the authors, for dynamic segregation resistance were performed. The effect of each variable on the test results were effectively summarized in a table. Increasing the w/c, CA/TA and Dmax decreased the superplasticizer demand and increased the flowability. When the slump flow, w/c and CA/TA were higher, viscosity was found to be lower. Higher values of CA/TA and Dmax were found to reduce the passing ability. Increasing the slump flow (or superplasticizer content), CA/TA and Dmax disturbed the sta-bility. Generally, the effects of w/c and slump flow on the SCC characteristics were more pronounced when compared to those of CA/TA and Dmax. Good correlations were obtained between several test results © Copyright (c) 2022 Alami, M. and Erdem, T. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivatives 4.0 International LicenseArticle 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: 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, GökmenArticle Citation - WoS: 7Citation - Scopus: 7A Comprehensive Study on Burst Pressure Performance of Aluminum Liner for Hydrogen Storage Vessels(ASME, 2021) Kangal, Serkan; Sayı, Abdülmecit Harun; Ayakdaş, Ozan; Kartav, Osman; Aydın, Levent; Artem, Hatice Seçil; Aktaş, Engin; Yücetürk, Kutay; Tanoğlu, Metin; Kandemir, Sinan; Beylergil, BertanThis paper presents a comparative study on the burst pressure performance of aluminum (Al) liner for type-III composite overwrapped pressure vessels (COPVs). In the analysis, the vessels were loaded with increasing internal pressure up to the burst pressure level. In the analytical part of the study, the burst pressure of the cylindrical part was predicted based on the modified von Mises, Tresca, and average shear stress criterion (ASSC). In the numerical analysis, a finite element (FE) model was established in order to predict the behavior of the vessel as a function of increasing internal pressure and determine the final burst. The Al pressure vessels made of Al-6061-T6 alloy with a capacity of 5 L were designed. The manufacturing of the metallic vessels was purchased from a metal forming company. The experimental study was conducted by pressurizing the Al vessels until the burst failure occurred. The radial and axial strain behaviors were monitored at various locations on the vessels during loading. The results obtained through analytical, numerical, and experimental work were compared. The average experimental burst pressure of the vessels was found to be 279 bar. The experimental strain data were compared with the results of the FE analysis. The results indicated that the FE analysis and ASSC-based elastoplastic analytical approaches yielded the best predictions which are within 2.2% of the experimental burst failure values. It was also found that the elastic analysis underestimated the burst failure results; however, it was effective for determining the critical regions over the vessel structure. The strain behavior of the vessels obtained through experimental investigations was well correlated with those predicted through FE analysis.Article Citation - WoS: 29Citation - Scopus: 31Reverse Flood Routing in Rivers Using Linear and Nonlinear Muskingum Models(American Society of Civil Engineers, 2021) Badfar, Meisam; Barati, Reza; Doğan, Emrah; Tayfur, GökmenOne of the key factors for flood modeling and control is the flood hydrograph, which is not always available due to lack of flood discharge observations. In reverse flow routing, hydraulic or hydrological calculations are performed from the downstream end to the upstream end. In the present study, a reverse flood routing approach is developed based on the Muskingum model. The storage function is conceptualized as linear and five different nonlinear forms. The Euler and the fourth-order Runge-Kutta numerical methods are used for solving the storage models. The shuffled complex evolution (SCE) algorithm is used for optimization of the flood routing parameters. The models are calibrated and validated with theoretical and actual hydrographs. The results indicate that the proposed methodology could substantially (up to almost 82%) improve comparison with observed inflows. The practical applicability of the proposed methodology is also validated in real river systems.