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 - Scopus: 1
    Anomalous Crustal Structure Beneath the Örenli-Eğiller Depression Zone, Inferred From Magnetotelluric Studies, Western Anatolia, Türkiye
    (TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2024) Chandrasekharam, Dornadula; Raju, K.; Subba Rao, P.B.V.; Baba, Alper
    In Türkiye, the prevalence of high radiogenic granites makes them ideal locations for initiating enhanced geothermal system (EGS) projects. One such occurrence of these granites is observed in the Kozak area of the Bergama region. To assess the energy potential of this site, a magnetotelluric (MT) survey was conducted, focusing on determining the depth distribution of the intrusive granite. The survey employed dimensionality analysis, utilizing Bahr skew and phase tensor analyses that denote a 2D subsurface nature up to 100 s and beyond that a 3D nature. In the present study, we interpreted MT data up to 100 s. The data collected, including rotated impedance tensors and tippers, were inverted using a nonlinear conjugate gradient algorithm integrated into the MT interpretation software of the WinG Link 2D inversion data modeling package. Multiple homogeneous half-space initial models were tested during the 2D inversion process. The findings indicate the existence of a midcrustal conductor associated with graphites and iron sulfides in the source region. This conductivity may be attributed to processes such as exsolution of metamorphic fluids, influx of mantle sources, or the entry of magmatic fluids through transcrustal fault zones. The findings indicate that the intrusive granite was emplaced along a NE–SW major fault, penetrating shallow crustal levels. The depth of this granite intrusion is determined to be 15 km, covering an outcrop area of 60 km². This detailed geological information allows a comprehensive assessment of the power-generating capacity of the intrusive granite. The results of this investigation contribute valuable insights for the development and optimization of Enhanced Geothermal System (EGS) projects in the region. © 2024, TUBITAK. All rights reserved.
  • Article
    Citation - Scopus: 2
    Application 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, Engin
    This 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: 3
    A 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 Muammer
    Hot 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: 1
    Citation - Scopus: 2
    Geothermal Power Corridor-Connecting the Middle East Countries
    (Maden Tetkik ve Arama Genel Mudurlugu-mta, 2023) Chandrasekharam, Dornadula
    The 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
    Efficiency of Shear Studs Manufactured From Threaded Bars on the Punching Behavior of Flat Slabs
    (Golden Light Publishing, 2023) Saatçi, Selçuk; Saatcı, Selçuk; Yaşayanlar, Yonca
    Punching resistance in flat slab systems in reinforced concrete structures is often provided with drop panels or shear reinforcement around columns. Shear studs are effectively used in these structures as shear reinforcement. However, factory-made shear studs may not be available in all locations and small quantities for small projects. Therefore, cheap shear studs that can be manufactured from widely available materials in small quantities can be very useful in certain cases. In this study, shear studs manufactured from threaded bars, widely available in hardware stores, are used for providing punching resistance to flat slabs. Stud heads were formed with T-section nuts. Four slab specimens, two with shear studs and two without, were cast and tested under concentrated loads at their mid-point. The slabs had 2150×2150×150 mm dimensions and they were cast with two different longitudinal reinforcement ratios. Test results showed that manufactured shear studs significantly increased the load and deformation capacities of the slabs. Slabs with shear studs were able to show up to three times higher bending deformations and they were able to sustain up to 50% higher loads. The study has shown that these studs can be effectively used for punching strengthening purposes in flat plate systems or in other cases where punching resistance is needed.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Magnetotelluric Investigations Over Geothermal Provinces of India: an Overview
    (TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2023) Prabhala, Bhaskhara Venkata Subba Rao; Pachigolla, Venkata Vijaya Kumar; Chandrasekharam, Dornadula; Deshmukh, Vasu; Singh, Ajay Kishore
    Magnetotelluric (MT) and audio-magnetotelluric (AMT) studies are sensitive to the geothermal fluids filling the faults and/ or fracture zones of the geothermal system. In India, MT/AMT studies have been carried out in NW Himalayas, central, eastern, and western India. In other areas, detailed MT/AMT studies need to be expedited. This review paper presents the art of geothermal exploration in India by using MT/AMT techniques and identifies potential zones that can be exploited for power generation and direct application. Reservoir characteristics, carbon emissions reduction methods, and levelised cost factor are also discussed. © TÜBİTAK.
  • Research Project
    Polimerlerin transport özelliklerinin gravimetrik yöntemle ölçülmesi
    (TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2003) Alsoy Altınkaya, Sacide; Tıhmınlıoğlu, Funda; Yürekli, Yılmaz
    Bu çalışmanın amacı ülkemizde oldukça yaygın bulunan sektörlerden biri olan boya sektöründe kullanılan metilmetakrilat bütilakrilat kopolimerinin kopolimerinin içinde metilmetakrilat monomerinin difüzyon katsayıları ve çözünürlüğünün ölçülmesi ve bu verilerden pratik bir korelasyon elde edilmesidir. Çalışmanın bir diğer amacı da bu korelasyonun türetilecek bir matematik model içinde kullanılarak boyada kalan monomerin havaya geçiş hızının ve monomerin havadaki konsantrasyonunun hesaplanmasıdır.
  • Research Project
    Çimento esaslı sensör üretimi
    (TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2013) Teomete, Egemen; Erdem, Tahir Kemal
    Depremler, malzeme bozulmaları ve diğer çevresel etkiler, yapıların performansını olumsuz etkiler. Yapı sağlığının izlenmesi can ve mal güvenliğini sağlamak için önemlidir. Gerinim pulları, yapı elemanlarının yüzeylerinden ölçüm alabilmekte, içinden ölçüm almak zor olmaktadır. Gerinim pullarının dayanıklılığı düşüktür, bu nedenle kısa süreler için kullanılabilinir. Gerinim pullarının pahalı olmaları çok sayıda kullanılmalarının önünde engeldir. Bu çalışmada, karbon ve çelik lifli, farklı lif uzunluğu ve lif hacimsel oranlarına sahip 46 farklı çimento matrisli karışım tasarlanmıştır. Basınç, yarmada çekme ve çentikli eğilme testleri ile, birim şekil değiştirmeye ve çatlak uzunluğuna en duyarlı karışım Çimento Esaslı Sensör (ÇES) olarak belirlenmiştir. Sıcaklığın ve nemin ÇES elektriksel direnci üzerindeki etkisi belirlenmiştir. Yükleme hızının ve nemin elektriksel direnç değişimi – birim şekil değiştirme ilişkisine etkileri araştırılmıştır. ÇES’in sensör özellikleri olan duyarlılık ve doğrusallık değerleri tespit edilmiştir. Elektrik akımının birim şekil değiştirmeye dik olduğu çapraz yükleme durumunun elektriksel direnç değişimine etkisi belirlenmiştir. Birim şekil değiştirme ve çatlak uzunluğu ile elektriksel direnç değişimi arasındaki mekanizmalar aydınlatılmıştır. ÇES içindeki aktif maddelerin zaman içinde birim şekil değiştirme -elektriksel direnç değişimi arasındaki ilişkiye ve elektriksel dirence etkisi belirlenmiştir.
  • Article
    Investigation of the Effect of Aggregate Specific Gravity on Optimum Bitumen Content of Hot Mix Asphalt
    (2022) Saltan, Mehmet; Karadağ, Öznur; Uz, Volkan Emre; Kaçaroğlu, Gizem; Gökalp, İslam
    In this study, effect of aggregate specific gravity, which is directly related to origin of aggregates used in hot mix asphalt on optimum bitumen content, indirect tensile strength and tensile strength ratio of hot mix asphalt, was investigated. Specific gravity (SG) values of one kind of limestone aggregate were calculated according to Turkish Standard (TS), American Society for Testing and Materials (ASTM) and American Association of State Highway and Transportation Officials (AASHTO) standards, separately. Although one kind of limestone aggregate and 50/70 penetration grade bitumen are used in the mixtures, different values were obtained in terms of optimum bitumen content, indirect tensile strength and moisture sensitivity due to differences in the specific gravity values of the aggregates. Optimum bitumen contents were found by using TS, ASTM and AASHTO standards as 5.03%, 4.75% and 4.59%, respectively. According to the cost – benefit analysis, it can be said that changes in aggregate specific gravity values, which were calculated, based on different standards provide economic benefit. Overall, the results indicated that specific gravity values of one kind of limestone aggregate used in hot mix asphalt have significantly affected optimum bitumen content and indirect tensile strength of the mixtures.