İnşaat Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1943

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Access Right: Open AccessEnd date: 2019

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Now showing 1 - 8 of 8
  • Article
    Contribution of Gravity Frames To Seismic Performance of Steel Moment Resisting Frames
    (2018-12-31) Zorlu, Mustafa; Şeker, Onur; Akbaş, Bülent; Shen, Jay; Boz, Mehmet; 01. MEF University
    Traditionally, lateral stiffness and strength of the gravity frames in steel buildings are neglected in structural analysis. During the past earthquakes, such as Northridge, USA, 1994 and Kobe, Japan, 1995, unexpected failures were detected at beam-to-column connections of steel moment resisting frames (MRFs). In the aftermath of these earthquakes, extensive research has been carried out to reveal the causes of these failures. Based on the detailed observations, it is likely that the reserve capacity provided by the gravity frames prevented the highly damaged steel buildings from collapsing, since majority of the moment-resisting connections failed prematurely during the Northridge earthquake (1994). Even though the influence of gravity frames (GFs) on structural behavior can be substantial, little attention is paid to evaluate its impact on structural response. With this paper, the contribution of interior GFs in seismic performance of special moment resisting steel frames (SMRFs) is evaluated. For this purpose, 4- and 9-story SMRFs were designed in accordance with the requirements of Draft Turkish Seismic Code (2016). The frames are, then, subjected to incremental dynamic analysis. To evaluate the contribution of the interior GFs on the overall seismic performance of structural system, inelastic behavior of shear tab (simple) connections at beam-to-gravity-only columns were idealized as semi-rigid joints. A general purpose structural analysis software, ETABS, is utilized for the analyses. The results of the study are presented in terms of story drifts, base shear vs. roof displacement.
  • Conference Object
    Seismic Evaluation of Square Hss Braces in Scbf Using Regression Analysis
    (ISEC Press, 2019-05) Shen, Jay; Akbaş, Bülent; Şeker, Onur; Faytarouni, Mahmoud; 01. MEF University
    Since the 1990s, structural engineering practice geared toward the use of hollow structural sections (HSS), notably square HSS, for their economy, and ease of design and construction. According to the AISC Seismic Provisions, during a severe earthquake, these braces could undergo post-buckling axial deformations 10 to 20 times their yielding deformation. However, recent experimental studies indicate that braces made of square HSS, depending on their size, width-to-thickness, and slenderness ratio, are vulnerable to fracture even prior to 10. Therefore, relying on past experimental studies comprised of a few square HSS specimens to develop seismic requirements for SCBF with square HSS could lead to underestimation of the seismic risk. This paper aims to evaluate the fracture risk of braces in existing SCBFs designed in accordance with AISC 341-05 and AISC 341-16 through incremental dynamic analyses (IDA) along with experimentally developed regression model that estimates fracture.
  • Conference Object
    Impact of Introducing Semi-Rigid Moment Frames on Seismic Response of Braced Frames
    (2019 ISEC Press, 2019-05) Shen, Jay; Akbaş, Bülent; Şeker, Onur; Faytarouni, Mahmoud; 01. MEF University
    Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.
  • Conference Object
    Citation - WoS: 7
    Citation - Scopus: 4
    2D Modeling Temperature Development of Mass Concrete Structures at Early Age
    (fib. The International Federation for Structural Concrete, 2017-08-06) Yıkıcı, Tahsin Alper; Chen R.H.L.; Chen, Roger H. L.; Yikici, Tahsin Alper; 02.04. Department of Civil Engineering; 02. Faculty of Engineering; 01. MEF University
    In this paper, a 2D finite volume analysis methodology was used to predict temperature development within three different bridge pier caps. MATLAB® was employed to generate a program that solves the governing heat transfer equation where development of thermo-physical concrete properties was defined as a function of degree of hydration. The rate of heat generation was obtained experimentally via adiabatic calorimetry and the activation energy was determined following the ASTM C 1074 procedure to implement equivalent age concept. 2D finite volume analysis results were presented in comparison with the recorded concrete temperatures from the field. Accordingly, temperature time histories at the center and the side surface of the bridge pier caps were predicted reasonably well using the concrete mixture information and the measured concrete hydration properties. © Springer International Publishing AG 2018.
  • Article
    Bitişik Yapıların Deprem Performanslarının Ayrı veya Bitişik Olarak Kırılganlık Eğrileri Yardımı ile İncelenmesi
    (Gazi Univ, 2015) Akbulut, Ali; Boduroğlu, M. Hasan; Boduroğlu, M. Hasan; 02.04. Department of Civil Engineering; 02. Faculty of Engineering; 01. MEF University
    Mevcut yapıların deprem performans, risk ve güçlendirme analizlerinde, yanındaki yapı ile olan ilişkisini uygun modelleme teknikleri ile analiz aşamasının içine dâhil ederek, sonuçların tekbaşına analiz edilmiş binalara göre olan farklılıklarını incelemek önemli bir konu olarak ortaya çıkmaktadır. Bu çalışmada, literatürdeki komşu binaların birbirleri ile olan etkileşim modelleri, statik itme analizi ve doğrusal olmayan hesap yöntemleri, deprem ivme kayıtlarının bir veri tabanından alınması ve tasarım spektrumuna göre ölçeklenmesi, zaman tanım alanına göre hesap yöntemi, hareket denkleminin Newmark-b yöntemi ile sayısal çözümü ve kırılganlık eğrileri ile bina performans seviyelerinin belirlenmesi konuları incelenmiştir. Bitişik (komşu) ve birbirine benzer binaların, deprem performanslarının birbirileri ile olan etkileşimli ve deprem yönüne göre değişen bir şekilde yapı blokları olarak ele alınıp, hasar görebilirlik-kırılganlık eğrileri yönünden değerlendirilmeleri incelenmiş ve binaların ayrı ayrı analiz edildikleri duruma göre daha farklı sonuçlar verdiği tespit edilmiştir.
  • Article
    Citation - WoS: 55
    Citation - Scopus: 58
    Experimental Evaluation of Eaf Ladle Steel Slag as a Geo-Fill Material: Mineralogical, Physical & Mechanical Properties
    (Elsevier Sci Ltd, 2017-11) Yıldırım, İrem Zeynep; Yıldırım, İrem Zeynep; Prezzi, Monica; 02.04. Department of Civil Engineering; 02. Faculty of Engineering; 01. MEF University
    Despite of significant efforts in the last decades towards utilization of steel slag in the construction industry, steel slag stockpiling and landfilling operations do not seem to be declining in steel-producing countries. Use of steel slag as a construction material requires understanding of its engineering properties and development of a methodology to address its swelling potential. This paper focuses on the results of a series of laboratory tests (grain-size analysis, X-ray diffraction, specific gravity, compaction, maximum and minimum dry unit weight, direct shear, and long-term swelling tests) performed on samples of electric-arc-furnace ladle (EAF(L)) steel slag to assess its potential to be used as a geo-material. Direct shear test results indicated that the EAF(L) steel slag exhibits comparable frictional properties to angular crushed sand. Based on the leachate concentration levels from TCLP analyses, the EAF(L) steel slag tested was classified as Type III Solid Waste. The long-term, one-dimensional (1D) swelling test results showed continued volumetric expansion even after more than 16 months of monitoring. Replacing 5-10% by weight of EAF (L) steel slag with Class C fly ash reduced the 1D swelling to negligible levels. (C) 2017 Elsevier Ltd. All rights reserved.
  • Article
    Lessons From the Rector of the First Fully Flipped Learning University
    (FLR The Flipped Learning 3.0 Magazine, 2018) Şahin, Muhammed; Şahin, Muhammed; 02.04. Department of Civil Engineering; 02. Faculty of Engineering; 01. MEF University
    Sahin: MEF Educational Institutions was founded in the 1970s by İbrahim Arıkan, an educator and businessman. In 1996, he founded MEF national and international K-12 schools in Istanbul and Izmir. In 2013, he founded MEF University. As both educator and entrepreneur, Arıkan was in a unique position to establish a university. He was aware the educational system was not well suited to the current needs of students and society and envisioned a totally new educational approach for MEF University. To find this approach, he brought me on board as founding rector. Having been rector of Istanbul Technical University from 2008 to 2012, I had a strong background in innovations in education. During our first meeting, Arıkan made it clear that if he was going to establish a university, it needed to be unique and take a different mentality to the educational needs of today’s students. I vividly remember Ibrahim emphatically declaring that if he could not make a change to higher education, he would call a halt to his aspirations for opening a university.
  • Other
    Laz Rektör Eğitimi Alt Üst Etti
    (Pazarlılar Derneği'nin Kültürel Yayını, 2016) Şahin, Muhammed; Şahin, Muhammed; 02.04. Department of Civil Engineering; 02. Faculty of Engineering; 01. MEF University
    MEF Üniversitesi Rektörü Prof. Dr. Muhammed Şahin, dünyada hiç bir üniversitede olmayan bir eğitim sistemini üniversitesinde uygulayarak bir ilke imza attı. Bir dönem İTÜ Rektörlüğü de yapan Şahin, Flipped Clasroom eğitim-öğretim modeli ile Türkiye'de eğitimi alt üst ettiklerini söylüyor. Akademi dünyasının tepkisi ise ilginçti: "Bu riski sadece bir Laz Rektör alabilirdi."