Yazarlar
- Aydin, Metin Mutlu(13)
- Araz, Onur(11)
- Coruh, Emine(7)
- Peker, Iskender(6)
- Üzülmez, Mehmet(6)
- Mızrak, Sefa(5)
- Ozturk, Kasif Furkan(5)
- Seferoğlu, Mehmet Tevfik(5)
- Çoruh, Emine(5)
- Akpinar, Muhammet Vefa(4)
- Alemdağ, Selçuk(4)
- Bayraktar, Alemdar(4)
- Bilgic, Abdulbaki(4)
- Cakir, Tufan(4)
- Comert, Resul(4)
- Dağ, Serhat(4)
- Çavdar, Özlem(4)
- Akinoglu, Bulent G.(3)
- Alemdag, Selcuk(3)
- Altunişik, Ahmet Can(3)
- Ar, Ilker Murat(3)
- Bilgilioglu, Burhan Baha(3)
- Eraslan, Selim(3)
- Erol, Ismail(3)
- Günen, Mehmet Akif(3)
- Nizetic, S(3)
- Ozden, Talat(3)
- Papadopoulos, A(3)
- Sevin, Sedat(3)
- Urak, Faruk(3)
- Yalvac, Sefa(3)
- Çavdar, Ozlem(3)
- Çelik, Muhammet(3)
- Çömert, Resul(3)
- Özdemir, Samed(3)
- Acar, Ramazan(2)
- Akbulut, Zeynep(2)
- Akgol, Kadir(2)
- Aksüt, Yavuz Selim(2)
- Altundaş, Suna(2)
Yayınlar
- MakaleYalnız künye2013Assessment of heavy metal accumulation in the roadside soil and plants of Robinia pseudoacacia, in Gumushane, Northeastern Turkey; [Yol kenari{dotless}ndaki topraklarda ve Robinia pseudoacacia bitkilerindeki aǧi{dotless}r metal birikiminin deǧerlendirilmesi, Gümüşhane, kuzeydoǧu Türkiye]
Vural, Alaaddin
The concentrations of heavy elements were studied in the soils and plants of Robinia pseudoacacia, along a highway passing through Gümüşhane City Center, Turkey. The aim of this study is to understand heavy metal accumulation due to dense traffic load, industrialization, urbanization, and/or geological features of the region. The assessment of the heavy metal accumulation of the soils is based on the Geoaccumulation Index and Enrichment Factor, and that of plants, is based on the Bioaccumulation Factor. According to the Geoaccumulation Index, soil samples were uncontaminated for Cr, Co, Cu, Rb, and Sr elements, uncontaminated to moderately contaminated for V, Ni, Ba, and Zn, and moderately to heavily-heavy contaminated for As. The contamination of soil samples changes from moderate-heavy-extremely contaminated degree for Pb. According to the Enrichment Factor; soil samples show, no enrichment-moderately-severe enrichment for V. Considering the Zn element, enrichment is in minor to severe enrichment. On the other hand, element enrichment is severe to very severe enrichment for As and that of Pb is minor to an extremely severe enrichment level. The data revealed that the soil in the study area is significantly contaminated for Zn, As, and Pb. Also, concentration levels of Cu, Fe, Mo, Ni, Sr, and Zn in the shoots of Robinia pseudoacacia at some location were determined as above and/or exceeded the upper limit of the normal range.
- DüzeltmeYayıncıda açık erişim2012Erratum: Probabilistic sensitivity analysis of two suspension bridges in Istanbul, Turkey to near- and far-fault ground motion (Natural Hazards and Earth System Sciences (2012) 12 (459-473))
Çavdar, O.
No abstract available.
- MakaleAçık Erişim2012Probabilistic sensitivity analysis of two suspension bridges in Istanbul, Turkey to near- and far-fault ground motion
Çavdar, Ö.
The aim of this paper is to compare the near-fault and far-fault ground motion effects on the probabilistic sensitivity dynamic responses of two suspension bridges in Istanbul. Two different types of suspension bridges are selected to investigate the near-fault (NF) and far-fault (FF) ground motion effects on the bridge sensitivity responses. NF and FF strong ground motion records, which have approximately identical peak ground accelerations, of the Kocaeli (1999) earthquake are selected for the analyses. Displacements and internal forces are determined using the probabilistic sensitivity method (PSM), which is one type of stochastic finite element method. The efficiency and accuracy of the proposed algorithm are validated by comparison with results of the Monte Carlo Simulation (MCS) method. The displacements and internal forces obtained from the analyses of suspension bridges subjected to each fault effect are compared with each other. It is clearly seen that there is more seismic demand on displacements and internal forces when suspension bridges are subjected to NF and FF ground motion.
- MakaleYalnız künye2011Finite element model calibration effects on the earthquake response of masonry arch bridges
Sevim, Baris; Bayraktar, Alemdar; Altunisik, Ahmet Can; Atamtürktür, Sezer; Birinci, Fatma
The focus of this paper is to illustrate the importance of model calibration and in situ vibration testing by comparing the finite element model predictions of the earthquake response of the two historical arch bridges, Osmanli and Senyuva, before and after model calibration. The three-dimensional finite element models of these two arch bridges, built in the ANSYS finite element program, are used to predict bridge dynamic characteristics, such as natural frequencies and mode shapes. Following the analytical study, ambient vibration tests were conducted to experimentally obtain dynamic characteristics of these two bridges. During ambient vibration tests, accelerometers were placed at several points on the bridge to collect the vibration response due to natural and operational excitation sources. Enhanced frequency domain decomposition and stochastic subspace identification techniques were used to extract the experimental natural frequencies, mode shapes and damping ratios. Finite element models of the two arch bridges were adjusted such that the model predictions reproduce the ambient vibration test results with increased fidelity. The behavior of the masonry arch bridges under earthquake excitation recorded during the Erzincan Earthquake in 1992 is simulated by both the initial and adjusted finite element models. The findings of this study emphasize the importance of model calibration and ambient vibration testing. (C) 2010 Elsevier B.V. All rights reserved.
- MakaleAçık Erişim2011Nonlinear earthquake behaviour of highway tunnels
Sevim, B.
This paper describes the Arhavi Highway Tunnel which has two tubes, its geometrical properties, finite element model, and the nonlinear earthquake behaviour under a huge ground motion considering soil-structure interaction. The Arhavi Highway Tunnel is one of the tallest tunnels constructed in the Black Sea region of Turkey as part of the Coast Road Project. The tunnel has two tubes and each of them is about 1000 m tall. In the study, the modal analyses of the tunnel considering soil-structure interaction are performed and natural frequencies and mode shapes are obtained. Then, nonlinear transient analysis of the tunnel using Drucker-Prager criteria is performed applying acceleration components of 1992 Erzincan, Turkey earthquake's ground motion. In the time history analyses, Rayleigh damping coefficients are calculated using main natural frequency obtained from modal analysis. Element matrices are computed using the Gauss numerical integration technique. The Newmark method is used in the solution of the equation of motion. Because too much memory for the analyses is required, the first 7.5 s of the ground motions, which is the most effective duration, is taken into account in calculations. The displacement and stress results are observed to be the allowable level of the concrete material.
- MakaleYalnız künye2011Assessment of nonlinear seismic performance of a restored historical arch bridge using ambient vibrations
Sevim, Bariş; Bayraktar, Alemdar; Altunişik, Ahmet Can; Atamtürktür, Sezer; Birinci, Fatma
Historic masonry arch bridges are vital components of transportation systems in many countries worldwide, ensuring the ready access of goods and services to millions of people. The structural failure of these historic structures would severely and adversely impact the economies of these nations due to the massive disruptions of transportation systems accompanying such failures. To successfully maintain these aging masonry structures, performance assessment must incorporate the unique mechanical characteristics of masonry. Therefore, the preferred analysis technique must go beyond a linear approach. This study assesses the earthquake performance of a restored historical masonry arch bridge through nonlinear finite element analysis incorporating the Drucker-Prager damage criterion. The case study structure is the Mikron Arch Bridge, a nineteenth century Ottoman Era structure built over the Firtina River near Rize, Turkey, and restored in 1998. The Mikron Arch Bridge was first subjected to ambient vibration testing, during which accelerometers were placed at several points on the bridge span to record the bridge vibratory response. The investigators then used Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques to extract the experimental natural frequencies, mode shapes, and damping ratios from these measurements. Experimental results were compared with those obtained by the linear finite element analysis of the bridge. Good agreement between mode shapes was observed during this comparison, though natural frequencies disagree by 8-10%. The boundary conditions of the linear finite element model of Mikron Arch Bridge are adjusted such that the analytical predictions agree with the ambient vibration test results. By introducing the Drucker-Prager damage criterion, the calibrated linear FE model was next extended into a nonlinear model. Nonlinear analysis of seismic behavior of Mikron arch bridge was performed considering the acceleration record of Erzincan earthquake in 1992 that occurred near the Mikron Bridge region. The displacement and stress results were observed to be allowable level of the stone material. Moreover, linear FE model calibrations elicited a significant influence on the nonlinear FE model simulations.
- MakaleYalnız künye2011Experimental and analytical system identification of Eynel arch type steel highway bridge
Altunişik, Ahmet Can; Bayraktar, Alemdar; Sevim, Bariş; Özdemir, Hasan
This paper describes a full scale arch type steel highway bridges, its finite element modelling and Operational Modal Analysis. Eynel Highway Bridge which has arch type structural system with a total length of 336 m and located in the AyvacIk county of Samsun, Turkey is selected as a case study. The bridge connects the villages which are separated with Suat Uǧurlu Dam Lake. The three dimensional finite element model is constructed using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three-orthogonal directions. The ambient vibration tests on the bridge deck under natural excitation such as traffic, human walking and wind loads are conducted using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification methods are employed namely, Enhanced Frequency Domain Decomposition method in the frequency domain and Stochastic Subspace Identification method in time domain. The correlation between the finite element model and experimental results is studied. Good agreement is found between dynamic characteristics in the all measurement test setups performed on the bridge deck. It is demonstrated that the ambient vibration measurements using Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are enough to identify the most significant modes of steel highway bridges. It is seen that there are some differences between analytical and experimental natural frequencies and experimental natural frequencies are generally bigger than the others.
- MakaleAçık Erişim2011Solutions for 4D cadastre - with a case study on utility networks
Döner, Fatih; Thompson, Rod; Stoter, Jantien; Lemmen, Christiaan; Ploeger, Hendrik; van Oosterom, Peter; Zlatanova, Sisi
The increasing complexity and flexibility of modern land use requires that cadastres need to manage information on the third and temporal (fourth) dimension. This article considers the registration of legal space of utility networks in cadastre in this 3D + time (=4D) context. A requirement analysis in three countries that have methods to register utility networks complying with their legal, organizational and technical structure (Turkey, the Netherlands and Queensland, Australia) is the basis for three alternatives for 4D cadastre to register utility networks. The three alternatives are analysed with respect to legal, organizational and technical cadastral requirements. This article presents a case study and a prototype from the Netherlands. In this country by law utilities are considered to be real estate objects with obligatory registration of ownership and geometry. This study shows that the 3D space and separate temporal attributes approach (state-based model) is a very promising solution to maintain temporal changes of utility networks and that this approach is to be preferred above the current practice, where the 3D and temporal aspects are not considered when registering a network.
- MakaleYalnız künye2011Solid waste management practices in Turkey
Berkun, Mehmet; Aras, Egemen; Anılan, Tugce
As an economically developing country, Turkey has very well operated integrated solid waste management applications structured on modern facilities, besides over 2,000 scattered open dump areas in the country. Integrated waste management applications seem eligible for the metropolitan cities like Istanbul and Izmit (Kocaeli). Attempts have not been encouraging for the scattered regional settlements using central storage sites due to financial shortages and received rejections from nearby settlements. Small-scale compact solid waste management systems with materials recycling and composting can be more suitable alternatives in the small-scale regional settlements. The major constituents of municipal solid waste are organic in nature and approximately a quarter of municipal solid waste is recyclable. Although paper, including cardboard, is the main constituent, the composition of recyclable waste varies strongly by the source or the type of collection point. Solid wastes need primary treatment in order to be suitable for incineration and composting. Turkey needs to give more emphasis on the usage of modern solid waste removal technologies to overcome the overgrowing solid waste disposal problems.
- MakaleYalnız künye2008Investigation of dynamic response of masonry minaret structures
Dogangun, Adem; Acar, Ramazan; Sezen, Halil; Livaoglu, Ramazan
Almost all historical minarets in Turkey were constructed using cut stone, masonry blocks or combination of these two materials. The structural and geometrical properties of each masonry minaret, or slender tower structure, depend on many factors including the structural knowledge and applications at the time of construction, experience of the architect or engineer, seismicity of the region, and availability of construction materials in that area. Recent earthquakes in Turkey have shown that most masonry minarets in high seismic regions are vulnerable to structural damage and collapse. In this study, in order to investigate the dynamic behavior of historical unreinforced masonry minarets, three representative minarets with 20, 25, and 30 m height were modeled and analyzed using two ground motions recorded during the 1999 Kocaeli and Duzce, Turkey earthquakes. The modal analyses of the models have shown that the structural periods and the overall structural response are influenced by the minaret height and spectral characteristics of the input motion. The dynamic displacement and axial stress time histories are computed at the critical points on the minarets. During recent earthquakes, most minaret failures occurred above the base of the structure. Consistent with the observed response, the largest stresses were calculated at the same location.
- MakaleYalnız künye2008Municipal solid waste characteristics and management in Gümüşhane, Turkey
Nas, S. Serkan; Bayram, Adem
This paper presents a general overview of the current municipal solid waste (MSW) management in Gümüşhane Province, Turkey. In order to characterize the solid waste stream in the Municipality of Gümüşhane, a long-term study was conducted over a 52-week period between the spring of 2004 and the winter of 2005. In this study, percentage of components and specific weight of the MSW, the composting parameters (moisture content, total organic carbon, total nitrogen and pH), organic matter content, calorific value and the heavy metal concentrations (Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mn, Co) of the compostable wastes sorted from the mixed MSW were determined and evaluated. In Gümüşhane, a mean of 70 tons of MSW are generated each day or 1 kg/day/capita. Approximately 4500 kg of the MSW were collected and sorted in a year, and the mean specific weight of these is 308 kg/m3. Approximately 30% of the MSW generated is compostable wastes and the yearly mean moisture content, organic matter content, C/N ratio and pH of these are 78%, 92.1%, 21.6/1 and 4.73, respectively, and approximately 24% of the MSW consists of recyclable materials. The recommended system deals with maximizing recycling and minimizing landfilling of the MSW, and consists of separation at source, collection, sorting, recycling, composting and sanitary landfilling. Heavy metal concentrations of the compostable wastes from the open dump were determined to decrease in the following order: Fe > Mn > Zn > Cr > Cu > Pb > Ni > Cd > Co.
- MakaleYalnız künye2007Traditional Turkish masonry monumental structures and their Earthquake response
Doğangün, Adem; Sezen, Halil; Tuluk, Ö. İskender; Livaoğlu, Ramazan; Acar, Ramazan
Many historical and new masonry minarets were damaged or collapsed during the 1999 earthquakes in Kocaeli and Duzce, Turkey. These and other recent earthquakes not only caused loss of property but also loss of many lives. The structural failures and resulting casualties have led to discussion and investigation of potential reasons for poor seismic performance of masonry minarets. The primary goal of this study is to review the construction practices for historical and new masonry minarets in Turkey and to discuss the seismic damage observed in those structures. The architectural and structural properties of contemporary and historical Ottoman minarets and their components are presented. For example, a very old special technique for reinforcing and linking adjacent stone blocks with iron pieces in the vertical and horizontal directions is discussed. The structural damage examples are used to better understand the reasons for the observed failure mechanisms. It is concluded that the transition region between the square minaret boot and cylindrical body was most vulnerable to damage, and the iron clamps used in historical minarets effectively prevented structural damage.
