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Yayın A precision estimation method for volumetric changes(IEEE, 2019-06) Akça, Mehmet Devrim; Stylianidis, Efstratios; Gruen, Armin W.; Altan, Mehmet Orhan; Hofer, Martin; Smagas, Konstantinos; Sanchez Martin, Victor; Walli, Andreas; Jimeno, Elisa; Garcia, AlejandroEarth surface changes are often computed by comparing the sequences of digital elevation models (DEMs) so called the DEM of difference (DoD) method. We present an operational DEM generation, co-registration and DoD comparison software in which the surface changes are quantified in metric units of volume. A practical method, which is based on the law of error propagation, is developed to estimate the theoretical precisions of volumetric changes. The proposed pipeline can estimate the change of object volumes (in terms of loss and gain) together with their precision numbers. Change of the forest volume in a fire effected region in a test site is analyzed for the validation. The method can be used for various change detection applications related to forestry as well as other topics such as earthworks, geomorphology, mining, and urbanization.Yayın Improvement of seismic performance of precast frames with cladding panels fastened by energy dissipative steel cushions(Springer, 2021-09) Özkaynak, Hasan; Khajehdehi, Arastoo; Yüksel, Ercan; Karadoğan, Hüseyin FarukPrecast reinforced concrete panels are commonly used as wall claddings in precast buildings. The cladding panels are generally evaluated as non-structural members and are joined to structural systems via mechanical, welding, and bolted dry connections. Several failures were observed in the last seismic events in Southern Europe, which demonstrate the deficiencies of the cladding connections in terms of strength and ductility. A comprehensive research activity named SAFECLADDING was conducted in Europe to provide knowledge for proper seismic design of precast structures with cladding panels. In this context, energy dissipative steel cushions were developed and evaluated through the extensive experimental and numerical studies. Steel cushions can provide robust interaction of the structural system with the cladding panels. This paper numerically evaluates the effects of cladding panels with steel cushions on the global seismic behaviour of the buildings. An existing representative industrial building is selected to perform intensive nonlinear dynamic analyses. Analyses performed on the bare and hybrid systems showed that the hybrid system has high performance in terms of story drifts, internal forces, and deformations with respect to the bare system. The overall drifts in longitudinal and transversal directions of the building are reduced by about 78 and 54%, respectively. Average residual drifts of cladding panels and steel cushions indicated that the applied steel cushion placement scheme has a promising re-centring capability during seismic action.Yayın Pros and cons of using building information modeling in the AEC industry(ASCE-AMER Soc Civil Engineers, 2019-08-01) Seyis Kazazoğlu, SenemAlthough a plethora of studies on building information modeling (BIM) have been conducted in the last decade, none of the previous studies collate and/or prioritize the benefits, risks, and challenges of BIM based on the data collected from a comprehensive literature review and subject matter experts (SMEs). In order to allow architecture, engineering, and construction (AEC) professionals and academics see the true potential of BIM in a wider context and help them understand its multiorganizational and multidisciplinary functions, there is an obvious necessity for identifying, classifying, and prioritizing the pros and cons of BIM; however, such a study is still currently absent in the AEC literature. The aim of this study is to identify, classify, and rank the pros and cons of BIM that address the benefits, challenges, and risks of BIM in the transition from computer-aided design (CAD). A literature review was performed and face-to-face semistructured interviews with SMEs on BIM were conducted for identification and classification purposes. A total of 41 types of benefits, 11 types of risks, and 13 types of challenges of BIM were identified via triangulation of literature review and face-to-face semistructured interviews with SMEs. The Delphi method was performed for prioritizing the benefits of BIM in terms of time, cost, and sustainability as well as the risks and challenges of BIM encountered in the transition process from CAD to BIM. The interrater agreement and significance-level statistics were performed to analyze and validate the consensus reached by the Delphi panel experts. This paper contributes to the existing body of knowledge on BIM by providing comprehensive identification and classification of the benefits, challenges, and risks of BIM, and prioritization of the benefits for BIM in terms of time, cost, and sustainability as well as the risks and challenges of BIM. The priority rankings of benefits, risks, and challenges of BIM ensure successful completion of projects and create additional value by allowing professionals to make well-informed decisions that support decreasing time and cost-related waste in the transition process from CAD to BIM.Yayın Energy dissipation characteristics of slab type buildings with special connectors(National Technical University of Athen, 2015-05-25) Şenol, Erkan; Dindar, Ahmet Anıl; Yüksel, Ercan; Karadoğan, Hüseyin FarukThe latest developments in the construction technologies and the materials facilitated the practicing engineers to go higher and energy-efficient buildings. However, the safety of the buildings and the residents has been an issue all the time. This is not an exception for the precast structures. The advantages of the precast elements are the quality assurance and the rapid erection on the site and challenged by the connection details and their performances during the extreme loading cases such as earthquakes. The utilization of a special mechanical connection of the precast members have been in the focus of the recent works in Istanbul Technical University (ITU-STEELAB). The prototypes of the proposed special connectors, called as cushion, were tested in STEELAB in order to determine the mechanical properties such as lateral and axial stiffness and the failure modes. Once the properties were determined, a hypothetical building of single story multi-bay slab type structure was modeled in the computer framework capable of substituting various parametric values into the model, processing and extracting the results for statistical analysis, SAMA. SAMA is developed based on the use of SAP 2000 OAPI functions called in MATLAB and Python scripts. In the hypothetical model, the cushions were modeled as link elements and placed between all the precast elements including foundation-cladding interface. Extensive non-linear time-history analysis was conducted to identify the damage localization by comparing the energy dissipation at each mechanical connector under ground motion records selected according to focal distance, site conditions and intensity. The preliminary results reveal that the cushions are effectively dissipating a significant amount of energy and mitigating the collapse of the precast elements. The more detailed conclusions will be discussed in the near future.Yayın Preface(Springer Science and Business Media Deutschland GmbH, 2021) Dutta, Subashisa; İnan, Esin; Dwivedy, Santosha Kumar[No abstract available]Yayın GIS aided vulnerability assessment for roads(Springer Science and Business Media B.V., 2022-04-21) Çalışkan, Berna; Atahan, Ali Osman; Kesten, Ali SercanRoad networks are vulnerable to natural disasters such as floods, earthquakes and forest fires which can adversely affect the travel on the network. However, not all road links equally affect the travel conditions in a given network; typically some links are more critical to the network functioning than the others. The first stage of study involves the investigation of geological conditions. Image classification used for extracting information classes from ‘Geological Map of Istanbul area’ image file. The resulting raster layer used to create thematic map. A reclassification was performed for lithologic types. The second stage involves analyzing topological situation. A slope map prepared and classified according to percentage of slope values. The third phase is the analysis and interpretation of the accumulated data to establish suitable and applicable road vulnerability scores. The information in the source data for each vulnerability factor are classified into three different vulnerability scores: +2 (considerably increases vulnerability), +1 (increases vulnerability) and 0 (does not increase vulnerability) by using a vulnerability score table. The study area was categorized into three different traffic analysis zones as: (1) least favorable area; (2) favorable area; (3) most favorable area. Vulnerability values obtained to measure serviceability of critical links in dense urban road networks and applies them to the case of ‘Beyoğlu’ region. Thematic layers were prepared using the Geographic Information System (GIS), and they were then combined to produce the serviceability of road links in the ‘Beyoğlu’ region. Consequently, A site specific vulnerability index is proposed, considering the serviceability of road links. A conceptual flowchart of the GIS processing steps taken to obtain the vulnerability index is illustrated.Yayın Historical analysis of economic, social and environmental impacts of the Europe-Asia crossings in Istanbul(Taylor & Francis Inc, 2016) Alpkokin, Pelin; Black, John Andrew; İyinam, Şükriye; Kesten, Ali SercanAchieving economic, social, and environmental sustainability of urban transport is one of the great contemporary societal challenges. By tracing urban land-use and transport policies and technological change in transport over a 60-year period in a case study of Istanbul, the authors demonstrate the displacement of more sustainable modes of transport (ferry, walking, and public transport) for a more automobile-dependent metropolis with road bridges across the Istanbul Strait (Bosphorus Strait). This article describes the main features, history, and status of the Europe-Asia crossings in Istanbul, thus framing a discussion of sustainability issues. Its originality is a discussion of sustainability through the economic, social, and environmental impacts of Europe-Asia crossings based on both a historical perspective and future prospects in order to assess whether current policies are leading toward more sustainable outcomes. The article concludes by emphasizing the impacts of policy decisions on transport infrastructures and highlighting some suggestions for policymakers.Yayın Photogrammetric monitoring of an artificially generated shallow landslide(Wiley-Blackwell, 2013-06) Akça, Mehmet DevrimAn artificial rainfall event was applied to a forested slope in Ruedlingen, northern Switzerland. The experiment triggered a landslide which resulted in mobilising about 130m3 of debris. The event was monitored by a photogrammetric network of four cameras, operating at 5 to 8 frames per second, in order to quantify spatial and temporal changes by tracking tennis balls pegged into the ground. Image measurements were performed using automated image matching methods, implemented through a software package developed in-house. Three-dimensional coordinates of the target points were estimated by running a customised type of bundle adjustment, achieving a positioning precision of +/- 1 center dot 8cm.Yayın İstanbul çevre yollarında yağmurun serbest akım hızı ve kapasiteye etkisinin irdelenmesi(TMMOB İnşaat Mühendisşeri Odası, 2019-10-12) Aksoy, Göker; Öğüt, Kemal SelçukTrafik tıkanıklığının en çok yaşandığı kentimiz, 15 milyondan fazla nüfusuyla şüphesiz İstanbul’dur. İki önemli anayolu (D100 Karayolu ve O2, O3, O4 Otoyolları) üzerinde, zirve saatlerde yapılan yolculukların daha uzun sürdüğü sürücüler tarafından benimsenmiş bir gerçektir. Aynı zamanda, yağmur gibi sürücü davranışını değiştirebilen çevresel bir dış etmenin tıkanıklığın etkilerini daha da arttırdığı tecrübe edilen bir durumdur. Ayrıca, otoyol gibi yüksek hızların yapıldığı yerlerde, diğer taşıtların sebep olduğu ıslak yol yüzeyinden havaya kalkan yağmur suları da görüşü olumsuz etkileyerek sürücülerin benzer şekilde tepki vermesine neden olur. Kısacası, insan algısının bir sonucu olarak izleme aralıkları yağmur etkisiyle artar, hızlar düşer. Kuşkusuz her sürücü benzer tepkiyi vermeyeceğinden, yolu kullanan taşıtlar arasındaki hız farkları yağışsız günlere göre daha da artacak ve artan hız farklarıyla yol daha güvensiz olacaktır. Bu çalışmada, İstanbul’un önemli çevre yolları olan, O2, O3, O4 Otoyolları ve D100 Karayolu üzerinde trafik akımının yağmur etkisi altındaki değişimi incelenmiştir. Çalışma alanı kent içi bölgede kalan, kapasite akımının ölçüldüğü, tıkanıklık sorunun yaşandığı bölgelerle sınırlandırılmış ve otoyollarda 50, D100 Karayolu’nda ise 62 km’lik bir bölge incelenmiştir. Trafik algılayıcılarıyla toplanan trafik akım verileri, meteorolojik verilerle birlikte değerlendirilmiştir. Toplam 7 farklı meteoroloji istasyonu ölçümleri 25 farklı trafik algılayıcısı ölçümleriyle eşleştirilmiş ve çözümlemelerde yer almıştır. Güneşli ve yağmurlu günler arasında trafik akımındaki farklılıklar açığa çıkarılmıştır. Yağmur etkisi altında, otoyollarda serbest akım hızı (SAH) %8,61, D100 Karayolu’nda ise %8,16 azalmış; kapasitenin ise sırasıyla %7,88 ve %9,07 oranlarında azaldığı bulunmuştur. Ayrıca boyuna eğimin artması her iki yol tipinde de SAH’ı azaltmakta, kapasite ise artan boyuna eğim ile birlikte yalnızca otoyollarda azalmaktadır.Yayın Improving the calibration time of traffic simulation models using parallel computing technique(Institute of Electrical and Electronics Engineers Inc., 2019-06) Dadashzadeh, Nima; Ergün, Murat; Kesten, Ali Sercan; Zura, MarijanThe calibration procedure for traffic simulation models can be a very time-consuming process in the case of a large-scale and complex network. In the application of Evolutionary Algorithms (EA) such as Genetic Algorithms (GA) and Particle Swarm Optimization (PSO) for calibration of traffic simulation models, objective function evaluation is the most time-consuming step in such calibration problems, because EA has to run a traffic simulation and calculate its corresponding objective function value once for each set of parameters. The main contribution of this study has been to develop a quick calibration procedure for the parameters of driving behavior models using EA and parallel computing techniques (PCTs). The proposed method was coded and implemented in a microscopic traffic simulation software. Two scenarios with/without PCT were analyzed using the developed methodology. The results of scenario analysis show that using an integrated calibration and PCT can reduce the total computational time of the optimization process significantly-in our experiments by 50%-and improve the optimization algorithm's performance in a complex optimization problem. The proposed method is useful for overcoming the limitation of computational time of the existing calibration methods and can be applied to various EAs and traffic simulation software.
