İnşaat Mühendisliği Bölümü Koleksiyonu

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

Browse

Now showing 1 - 17 of 17

Citation - WoS: 7
Citation - Scopus: 4
2D Modeling Temperature Development of Mass Concrete Structures at Early Age
(FIB. The International Federation for Structural Concrete, 2018) Yikici, T.A.; Chen, R.H.L.
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. © 2022 Elsevier B.V., All rights reserved.
Aktif Öğrenme Modelini Kullanan Mef Üniversitesi’nin İddiası: “öğrenmede Sınırsız Özgürlük”
(KobiEfor, 2020) Şahin, Muhammed
MEF Üniversitesi, yüksek öğretimde dönüşümün anahtarı olarak kabul edilen Flipped Learning modelini ilk uygulayan kurum olarak ilk mezunlarını 2018’de verdi. Aktif öğrenme modelinde yetişen öğrencilerin mezuniyet sonrası işe girme ve öğrenime devam etme oranı yüzde 96’yı buldu. Üniversite bu yıl da finalleri kaldırarak proje haftasını getirdi.
Citation - WoS: 2
Citation - Scopus: 2
Assessment of the Disaster Recovery Progress Through Mathematical Modelling
(TMMOB İnşaat Mühendisleri Odası, 2020) Dikmen, Seyyit Ümit; Sönmez, Murat; Akbıyıklı, Rıfat
Natural disasters, especially major earthquakes, cause widespread devastation in the built environment. Hence, the major component of the recovery in its aftermath constitutes a chain of projects starting at different times, having different costs and durations. In this study, the post disaster recovery curve modelled through a mathematical approach taking into account these properties of the projects. The approach followed is based on the project S-curve concept that provides the opportunity to simulate the progress by outlining the project spending. Well-known mathematical functions are adapted to model the project spending and the handover processes. Monte Carlo simulation is performed to evaluate the general behavior of the recovery curve using the model developed. Weibull distribution is used to generate the model’s parameters. Results of the Monte Carlo simulation demonstrate that the recovery process exhibits an S-shape, the duration of initial portion and the slope of the bulk portion being significantly governed by the level of preparedness of the community.
Bitişik Yapıların Deprem Performanslarının Ayrı veya Bitişik Olarak Kırılganlık Eğrileri Yardımı ile İncelenmesi
(2015) Akbulut, Ali; Boduroğlu, M. Hasan
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.
Contribution of Gravity Frames To Seismic Performance of Steel Moment Resisting Frames
(2018) Zorlu, Mustafa; Şeker, Onur; Akbaş, Bülent; Shen, Jay
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.
Deprem Yalıtımlı ve Geleneksel Binalarda Tesisatlar İçin Sismik Koruma Hesabı ve Gereksinimi
(2023) Şadan, Bahadır
İnşaat mühendisleri, olası büyük bir deprem senaryosu için, binanın taşıyıcı elemanlarını ve içinde yaşayan insanların can güvenliğini sağlamak için tasarım yapmaktadırlar. Halbu - ki, büyük bir deprem sonrası mali kayıp tabloları incelendiğinde, mali kayıpların en büyük bölümünü yapısal olmayan elemanlardaki hasarın oluşturduğunu görebiliriz. Dışarıdan bakıldığında hasarsız gözüken, taşıyıcı elemanlarında hasar olmayan bir binanın içerisine girildiğinde, sadece kendi ağırlığını taşımak için askılanmış ve doğru sismik koruma uygulan- mamış tesisatların, tavaların ve diğer tavana asılı ekipmanların, yüksek deprem ivmesi nedeni ile hasar gördüğü ve binanın kullanılamaz hale geldiği gözlemlenebilir. Bu durum özellikle deprem sonrası hemen hizmet vermesi gereken kritik binalar için (ör. hastaneler, ulaşım ve haberleşme yapıları vb.) daha büyük önem taşımaktadır. Sağlık Bakanlığı bu bağlamda, 2013 yılında yayınladığı bir genelge ile, 1. ve 2. derece deprem bölgesindeki, 100 ve üzeri yatak kapasiteli tüm devlet hastanelerinde sismik izolatörler ile deprem yalıtımını zorunlu hale getirmiştir. Deprem yalıtımı, binaya etkiyen deprem ivmelerini dolayısı ile deprem kuvvetlerini çok büyük oranda sönümleyerek, sadece bina taşıyıcı siste- minin değil aynı zamanda diğer muhteviyatın (tesisatlar, ivmeye hassas cihazlar vb.) deprem sırasında korunmasını sağlamaktadır. Fakat bu azaltma deprem etkilerini tamamen yok et- mediği için tesisatlarda sismik koruma yapılmasına gerek olmadığı anlamına gelmemektedir. Bu bildiride, 18 Mart 2018, 30364 sayılı Resmi Gazete’de yayınlanarak, 1 Ocak 2019 tarihi itibari ile resmi olarak yürürlüğe giren Türkiye Bina Deprem Yönetmeliği’ne (TBDY) göre elektrik ve mekanik tesisatların sismik koruma hesabı tariflenmektedir. Ayrıca yine TBDY’e göre deprem yalıtımlı binalarda sismik koruma hesabı gereksinimi irdelenmektedir.
Citation - WoS: 51
Citation - Scopus: 55
Experimental Evaluation of Eaf Ladle Steel Slag as a Geo-Fill Material: Mineralogical, Physical & Mechanical Properties
(2017) Yıldırım, İrem Zeynep; Prezzi, Monica
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.
Citation - WoS: 5
Citation - Scopus: 7
Factors Affecting Site-Specific Response Analysis
(Taylor and Francis, 2022) Tönük, Gökçe; Ansal, Atilla M.
The engineering purpose of a site-specific response analysis is to estimate the uniform hazard acceleration spectrum on the ground surface for a selected hazard level. One of the mandatory components for site response analyses is one or more representative acceleration time histories that need to be scaled with respect to the calculated seismic hazard level for the selected site. The selection and scaling procedures of earthquake acceleration records play an important role in this approach. The effects and differences in using two different scaling approaches are studied: scaling with respect to ground motion parameters and response spectrum scaling. A set of homogeneous ground motion prediction relationships are developed for peak ground acceleration, peak ground velocity, root-mean-square acceleration, Arias intensity, cumulative absolute velocity, maximum spectral acceleration, response spectrum intensity, and acceleration spectrum intensity based on a uniform set of acceleration records for ground motion parameter scaling.The uncertainties associated with site response analysis are considered as epistemic and aleatory uncertainties in source characteristics, soil profile, and soil properties. Aleatory variability is due to the intrinsic randomness of natural systems; it cannot be reduced with additional data (Passeri et al. 2020), however; its variability may be modeled by probability distribution functions. Thus, one possibility is to determine the probability distribution of the acceleration spectrum calculated on the ground surface for all possible input acceleration records, site profiles, and dynamic soil properties. The variability in the earthquake source and path effects are considered using a large number of acceleration records compatible with the site-dependent earthquake hazard in terms of fault mechanism, magnitude, and distance range recorded on stiff site conditions. Likewise, a large number of soil profiles may be considered to account for the site condition variability. The uncertainties related to dynamic soil properties may be considered as possible variability of maximum dynamic shear modulus in site response analyses. A methodology is proposed to estimate a uniform hazard acceleration spectrum on the ground surface based on the probabilistic assessment of the factors involved in site response analysis. The uniform hazard acceleration spectra obtained from a case study are compared with the spectra calculated by probabilistic models proposed in the literature.
Impact of Introducing Semi-Rigid Moment Frames on Seismic Response of Braced Frames
(2019 ISEC Press, 2019) Shen, Jay; Akbaş, Bülent; Şeker, Onur; Faytarouni, Mahmoud
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.
Laz Rektör Eğitimi Alt Üst Etti
(Pazarlılar Derneği'nin Kültürel Yayını, 2016) Şahin, Muhammed
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."
Lessons From the Rector of the First Fully Flipped Learning University
(FLR The Flipped Learning 3.0 Magazine, 2018) Şahin, Muhammed
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.
Citation - WoS: 1
Citation - Scopus: 1
Probabilistic Seismic Microzonation for Ground Shaking Intensity, a Case Study in Türkiye
(Springer, 2023) Tönük, Gökçe; Ansal, Atilla
The purpose of seismic microzonation is to estimate earthquake characteristics on the ground surface based on a probabilistic approach to mitigate earthquake damage in the foreseeable future for the new buildings, as well as for the existing building stock. The probabilistic analysis and related results are very important from an engineering perspective since the nature of the problem can only be dealt with in a probabilistic manner. The uncertainties associated with these analyses may be large due to the uncertainties in source characteristics, soil profile, soil properties, and building inventory. At this stage, the probability distribution of the related earthquake parameters on the ground surface may be determined based on hazard-compatible input acceleration-time histories, site profiles, and dynamic soil properties. One option, the variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the site-dependent earthquake hazard. Likewise, large numbers of soil profiles may be used to account for the site-condition variability. The seismic microzonation methodology is proposed based on the probabilistic assessment of these factors involved in site response analysis. The second important issue in seismic microzonation procedure is the selection of microzonation parameters. The purpose being mitigation of structural damage, it is possible to adopt earthquake parameters like cumulative average velocity (CAV) or Housner intensity (HI) that was observed to have better correlation with building damage after earthquakes. A seismic microzonation procedure will be developed with respect to ground shaking intensity considering probabilistic values of the cumulative average velocity (CAV) or Housner intensity (HI).
Seismic Evaluation of Square Hss Braces in Scbf Using Regression Analysis
(ISEC Press, 2019) Shen, Jay; Akbaş, Bülent; Şeker, Onur; Faytarouni, Mahmoud
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.
Seismic Performance of Damaged Code-Conforming Rc Columns Repaired With Sustainable Structural Mortar
(Elsevier B.V., 2024) Kolemenoglu, S.; Halici, O.F.; Demir, C.; Aydemir, C.; Aydemir, M.E.; Ilki, A.
Examining the seismic performance of damaged reinforced concrete (RC) structures after repair applications is vital for an effective post-earthquake disaster management policy. However, the number of experimental studies investigating the seismic behavior of repaired RC members is insufficient, especially for structural members that have endured slight or moderate level damages. In this study, four identical large-scale code-conforming RC columns were tested under combined effects of axial load and reversed cyclic lateral displacements. The reference column was tested until failure, while the remaining three columns were first imposed to lateral displacements until the formation of damages at different levels, then repaired with structural repair mortar that contains recycled raw materials without removing axial load and tested again until failure. The primary objectives of the experimental program are to enhance the knowledge on the post-earthquake performance of damaged RC columns and to investigate the effects of repair applications after slight and moderate damage levels. This paper provides details on the effectiveness of the aforementioned repair technique on the seismic performance of code-complying RC columns damaged at different damage levels. © 2024 Elsevier B.V.. All rights reserved.
Structural Assessment of the 13th Century Great Mosque and Hospital of Divrigi: a World Heritage Listed Structure
(12th International Conference on Structural Analysis of Historical Constructions (SAHC 2021), 2021) İlki, Alper; Berlucchi, Nicola; Demir, Cem; Şanver, Ali Naki; Hurata, Ali; Cömert, Mustafa; Halıcı, Ömer Faruk
The Great Mosque and Hospital of Divrigi is located in the central eastern partof Turkey, in Divrigi, Sivas. The historical facility consists of a monumental mosque anda two-story hospital, which are adjacent to each other. The structure dates back to13th century Mengujekids period and has been listed by the UNESCO as a World Heritagesince 1985. Great Mosque and Hospital of Divrigi is particularly notable for its monumentalstone portals that are decorated with three-dimensional ornaments carved fromstone. The structural system of the monument consists of multi-leaf stone masonrywalls and stone piers that support the roof structure which consists of stone and brickarches and vaults. The structure is located about 90 km away from the North AnatolianFault Line, that has been causing several destructive earthquakes. Consequently, thestructure is prone to destructive seismic activities. In this study, after a briefintroduction on the structural system and current condition of the structure, thestructural performance of the Great Mosque and Hospital of Divrigi is investigatedthrough site observations and structural analyses. For this purpose, linear and nonlinear 3Dfinite element models of the structure are developed and the structure is examined under theeffects of vertical loads and seismic actions. In the light of the analyses results,recommendations for potential interventions are outlined for further preservation of thestructure.
Citation - Scopus: 19
The Modified Post-Earthquake Damage Assessment Methodology for Tcip (tcip-Dam
(Springer, 2021) Cömert, Mustafa; Ilki, Alper; Halıcı, Ömer Faruk; Demir, Cem
Post-Earthquake damage assessment has always been one of the major challenges that both engineers and authorities face after disastrous earthquakes all around the world. Considering the number of buildings in need of inspection and the insufficient number of qualified inspectors, the availability of a thorough, quantitative and rapidly applicable damage assessment methodology is vitally important after such events. At the beginning of the new millennia, an assessment system satisfying these needs was developed for the Turkish Catastrophe Insurance Pool (TCIP, known as DASK in Turkey) to evaluate the damages in reinforced concrete (RC) and masonry structures. Since its enforcement, this assessment method has been successfully used after several earthquakes that took place in Turkey, such as 2011 Van Earthquake, 2011 Kutahya Earthquake, 2019 Istanbul Earthquake and 2020 Elazig Earthquake to decide the future of damaged structures to be either ‘repaired’ or ‘demolished’.
Citation - WoS: 3
Citation - Scopus: 4
Time - Cost Relationships for Superstructure Projects in Turkey
(TMMOB İnşaat Mühendisleri Odası, 2020) Dikmen, Seyyit Ümit; Akbıyıklı, Rıfat; Sönmez, Murat
The concept of time-cost relationship in construction projects was first introduced by Bromilow. Bromilow used the data of the superstructure projects completed in Australia in the creation of the proposed time-cost model (BTC model). The aim of this study is to determine the time-cost relationship of superstructure projects in Turkey. Time and cost data of superstructure projects completed between the years of 1999-2018 was used in the study. Data was grouped primarily on the basis of the intended use of buildings (individual buildings, educational buildings, hospitals, industrial buildings and social housing), and then time-cost relationships were separately determined for each group. In addition, the effects of the parameters such as exchange rates and the number of non-working days on the time-cost relationship were investigated statistically.

Browse

Browsing İnşaat Mühendisliği Bölümü Koleksiyonu by Access Right "info:eu-repo/semantics/openAccess"