Yazarlar
- Peker, Iskender(23)
- Araz, Onur(16)
- Erol, Ismail(15)
- Ar, Ilker Murat(12)
- Bayraktar, Alemdar(10)
- Seferoğlu, Mehmet Tevfik(10)
- Aydin, Metin Mutlu(9)
- Günaydin, Murat(9)
- Adanur, Süleyman(8)
- Altunişik, Ahmet Can(8)
- Basoglu, Mustafa Engin(8)
- Akyol, Mehmet(7)
- Yanarateş, Cağfer(7)
- Akpinar, Muhammet Vefa(6)
- Altan, Aytaç(6)
- Barut, Abdulkadir(6)
- Başoğlu, Mustafa Engin(6)
- Cakmak, Recep(6)
- Searcy, Cory(6)
- Çavdar, Özlem(6)
- Baki, Birdogan(5)
- Benli, Tolga(5)
- Gergin, Ramazan Eyüp(5)
- Kahya, Volkan(5)
- Kuzulugil, Kenan(5)
- Ozden, Talat(5)
- Pala, Fahrettin(5)
- Seferoğlu, Ayşegül Güneş(5)
- Sevim, Bariş(5)
- Yilmaz, Tekin(5)
- Adanur, S.(4)
- Adanur, Suleyman(4)
- Aksüt, Yavuz Selim(4)
- Altunisik, Ahmet Can(4)
- Aydin, Musa(4)
- Cakir, Mehmet Ali(4)
- Cavusoglu, Ibrahim(4)
- Coruh, Emine(4)
- Ercikdi, Bayram(4)
- Gunaydin, M.(4)
Yayınlar
- MakaleYalnız künye2018Bearing capacity and slope stability assessment of rock masses at the Subasi viaduct site, NE, Turkey
Kaya, Ayberk; Bulut, Fikri; Dağ, Serhat
This study investigates the bearing capacity of rock masses and stability of slopes at the Subasi viaduct site which is a part of the improvement project of the Artvin–Hopa government highway between KM 6 + 500 and 13 + 787 in NE Turkey. The geotechnical studies were performed in three stages. Firstly, the bearing capacity of moderately weathered andesitic tuff was evaluated using the empirical equations. Secondly, the major principal stress and vertical displacement due to the viaduct and traffic loadings at the level of foundations were determined by the finite element method (FEM). The vertical displacement value and comparison of bearing capacity and major principal stress show that any problem is not expected at the viaduct site in terms of the bearing capacity. Finally, the stability of slopes at the viaduct site was investigated using kinematic, limit equilibrium, and finite element method-based shear strength reduction analyses methods. It was concluded that no discontinuity controlled failures at the slopes are expected. However, a circular failure is possible to occur at the face slope excavated in highly weathered andesitic tuff. After support application, the long-term stabilization of face slope has been achieved. Consequently, it is suggested that the empirical, analytical, and numerical methods should be combined for a more reliable construction design.
- MakaleYalnız künye2018Solving power transmission line routing problem using improved genetic and artificial bee colony algorithms
Eroğlu, Hasan; Aydin, Musa
In engineering studies, finding the best route from a start point to an end point on pixel-based weighted maps is a big problem for researchers. For this problem many methods and algorithms have been developed until now. The “cost distance” (CD) and “cost path” (CP) tools that are used by a modified Dijkstra’s algorithm and used by Environmental Systems Research Institute’s (ESRI) ArcGIS Desktop 10 software are very fast and most preferred solutions for route optimization problems. Despite the advantages of these tools, they have the disadvantage of making a lot of curves with big angles. Especially in some engineering studies like power transmission lines’ routing, the angle of the curves of the lines should not have big values. For overcoming this problem both genetic algorithm (GA) and artificial bee colony (ABC) algorithm that have been improved and adapted for the problem were used as powerful optimizers to find the best routes with fewer curves in those kinds of optimum route problems. New functions like smart direction sensing and improved random functions were developed for application of GA and ABC algorithms in power transmission lines routing studies. This study showed that the ABC algorithm’s performance is better than GA. The accuracy of the algorithms was proven by comparing the results with the CD–CP tools’ results. The experimental results showed that the improved algorithms gave better performance than Dijkstra’s algorithm.
- BildiriAçık Erişim2018Determining photovoltaic module performance and comparisons
Karaveli, Abdullah Bugrahan; Ozden, Talat; Akinoglu, Bulent G.
Knowing electricity production potential of a photovoltaic (PV) system prior to installation is very beneficial for the investor to see the feasibility of the investment. There are three procedures that can be followed to calculate the potential electricity production of any system under different conditions. These are installation of sample systems and gathering data over time, the use of some databases/software programs to reach the performances and developing new model/methodology to make these estimations. It is obvious that installation of PV systems everywhere is neither technically nor economically conceivable. On the other hand, global software programs may not reflect local conditions to calculations. Consequently, there is a need to develop methodology that is able to derive location specific equations and coefficients and make accurate estimations. Its accuracy can be controlled by validating the results for some locations with the measured values from already installed PV power plants (PV PP). So, in this study we initially develop a methodology to calculate efficiency and electricity production performance of some modules for Ankara and compare the results with the measured values owing to the system installed on the roof of the Middle East Technical University Solar Energy Research Center (METU GUNAM) in Ankara/Turkey. The methodology initially calculates solar irradiation falling on the modules that is the input. Then the performance of the module is calculated by using developed methodology. There are also some online software programs to calculate the performances, such as EU PVGIS and PV WATTS. We analyzed and used these software programs and compare their results with the results of newly developed methodology. As proven through mean-bias error (MBE), root-mean-square error (RMSE) and mean absolute error (MAE) statistical comparison methods, the methodology of this study has given the most accurate results.
- BildiriAçık Erişim2018Impacts of a photovoltaic power plant for possible heat island effect
Demirezen, Emre; Ozden, Talat; Akinoglu, Bulent G.
Today, solar energy conversion technologies take a significant place within the efforts of obtaining renewable and sustainable energy around the world, and show a rapid progress. One of the most common technologies is photovoltaic power plants (PVPP) which are built using PV modules that provide electricity directly from sunlight. These plants are qualified as one of the pioneering applications among clean energy production methods. However, as the modules cover large areas and as they are produced by mostly dark-colored solar cells, an environmental debate has already been opened via some recent studies in the literature: Do they alter the solar reflectivity (albedo) of the region's surface where they are installed, and in turn affect the typical microclimate characteristics of that region such as the local air temperatures, humidity, pressure and wind speed? Considering also the additional heat that the modules radiate while producing electricity, the main probable result should be expected as Heat Island Effect (HIE). HIE has been particularly discussed for about last 10 years. Basically, this effect defines the day-night and inter-seasonal variations of local temperatures due to artificial changes on the natural land surface. Accordingly, when an urbanized area is compared with the neighboring rural areas, the difference is specifically named as Urban Heat Island (UHI) effect. In the present work, we are conducting a field research with in-situ measurements taken by the two weather monitoring stations inside and outside a PVPP in the district Tavsanli (Kutahya, Turkey). We also provide the meteorological data of Tavsanli station from Turkish State Meteorological Service (TSMS), which is the nearest weather monitoring station to the PVPP under inspection. These stations have been collecting the data of air temperature, relative humidity, average wind speed and atmospheric pressure every 10 minutes since October 2017. We used two statistical methods to compare and interpret the first 8-month data of all the three stations. We considered the statistical significance tests for both the first 8 months as a whole and dividing it into two 4 months before and after the PVPP becomes operational. We found that the measurements of the three stations differ significantly for most of the weather parameters. We also carried out pairwise tests and showed that each pair has significant differences for most parameters.
- MakaleYalnız künye2018Modal parameter identification of RC frame under undamaged, damaged, repaired and strengthened conditions
Altunişik, Ahmet Can; Karahasan, Olguhan Şevket; Genç, Ali Fuat; Okur, Fatih Yesevi; Günaydin, Murat; Kalkan, Ebru; Adanur, Süleyman
Structures are built on a design and then damaged in time by natural and manmade effects, repaired and strengthened for reusing. Determination of the structural behavior is very important to avoid future disaster. Operational Modal Analysis has been widely used recently to determine the inherent modal parameters of engineering structures and give significant information about the structural condition. Also, this method can be used to further studies such as model updating, damage detection and health monitoring. In this paper, it is aimed to investigate the changes of modal parameters considering undamaged, damaged, repaired and strengthened conditions using ambient vibration tests. For this purpose, a reinforced concrete frame model having two-floor with two spans in the longitudinal direction considering ½ geometric scales is built in laboratory. Four different cases are considered to emerge the efficiency of this procedure and the undamaged RC model is measured firstly to determine the initial modal parameters. Secondly, the lateral forces are applied to floor levels to obtain the damages, especially in beam-column joints. Thirdly, the damaged model is repaired using injection material and lastly strengthened with Carbon Fiber Reinforcement Polymer. It is also examined that what rate the dynamic characteristics return to back after repairing and strengthening studies by the comparison with undamaged condition? In addition to this the evaluation of carbon fiber reinforcement polymer effectiveness in strengthening for real applications is presented. It is seen that ambient vibration test is enough to identify the modal parameters of engineering structures for different conditions. The modal parameters are decreased distinctly with damages, and reverted almost initial condition with strengthening.
- MakaleYalnız künye2017System identification of arch dam model strengthened with CFRP composite materials
Altunisik, A.C.; Gunaydin, M.; Sevim, B.; Adanur, S.
This paper presents the structural identification of an arch dam model for the damaged, repaired and strengthened conditions under different water levels. For this aim, an arch dam-reservoir-foundation model has been constructed. Ambient vibration tests have been performed on the damaged, repaired and strengthened dam models for the empty reservoir (0 cm), 10 cm, 20 cm, 30 cm, 40 cm, 50 cm and full reservoir (60 cm) water levels to illustrate the effects of water levels on the dynamics characteristics. Enhanced Frequency Domain Decomposition Method in the frequency domain has been used to extract the dynamic characteristics. The dynamic characteristics obtained from the damaged, repaired and strengthened dam models show that the natural frequencies and damping ratios are considerably affected from the varying water level. The maximum differences between the frequencies for the empty and full reservoir are obtained as 16%, 33%, and 25% for damaged, repaired and strengthened model respectively. Mode shapes obtained from the all models are not affected by the increasing water level. Also, after the repairing and strengthening implementations, the natural frequencies of the arch dam model increase significantly. After strengthening, between 46-92% and 43-62% recovery in the frequencies are calculated for empty and full reservoir respectively. Apparently, after strengthening implementation, the mode shapes obtained are more acceptable and distinctive compared to those for the damaged model.
- BildiriYalnız künye2017A day ahead hourly solar radiation forecasting by artificial neural networks: A case study for Trabzon province; [Yapay Sinir Aǧlari ile Gün Öncesi Saatlik Güneş Radyasyonu Tahmini: Trabzon İli Örneǧi]
Çevik, Sibel; Çakmak, Recep; Altaş, Ismail Hakki
The integration of renewable energy sources to the electrical grid leads to some issues in the grid because of intermittent and variable characteristics of renewable energy sources such as wind and solar. It has been predicted that the solar based electricity production will has highest annual increase rate among the other renewable sources. Due to the intermittent and volatile nature of the solar energy in an electricity grid where photovoltaic systems are intensive, load planning is essential. Therefore, day ahead solar radiation forecasting will contribute to the load planning studies. Artificial neural networks are one of the methods that are applied frequently and successfully in forecasting studies. In this study, a cause effect based artificial neural network (ANN) has been designed and performed for day ahead hourly solar radiation forecasting in Trabzon province. A similar day selection algorithm has been utilized to get more accurate forecasting by the ANN. The designed ANN has been trained and tested in MATLAB simulation environment without using ready codes of MATLAB ANN toolbox. The obtained results reveal that the designed ANN forecasts the solar radiation with acceptable error for a place such as Trabzon which has rainy and cloudy weather conditions.
- MakaleYalnız künye2017An Investigation of the Seismic Behaviour of an Ancient Masonry Bastion Using Non-Destructive and Numerical Methods
Altunisik, A.C.; Adanur, S.; Genc, A.F.; Gunaydin, M.; Okur, F.Y.
Determining the structural behavior of masonry structures is a challenge due to their lack of homogeneity. The seismic behavior of masonry structures is especially complex. The aim of this study was to examine the structural behavior of Zağanos Bastion using both experimental and numerical methods. The Operational Modal Analysis technique, including the Enhanced Frequency Domain Decomposition Method, and the Stochastic Subspace Identification Method were used to illustrate experimentally the dynamic characteristic of the bastion. A finite element model was developed using ANSYS software in order that the dynamic characteristics of the bastion, including natural frequencies and mode shapes, could be calculated numerically. Seismic analysis was carried out using the 1999 Kocaeli earthquake ground motion record to determine the linear and nonlinear seismic behavior of the bastion. The Turkish Earthquake Code and its general technical specifications were used to evaluate the seismic results. The results show that the maximum and minimum principal stresses exerted on the masonry components exceeded the code requirements at some points, but in general the requirements for the stresses were satisfied.
- MakaleYalnız künye2016Retrofitting Effect on the Dynamic Properties of Model-Arch Dam with and without Reservoir Water Using Ambient-Vibration Test Methods
Altunisik, Ahmet Can; Günaydin, Murat; Sevim, Baris; Bayraktar, Alemdar; Adanur, Suleyman
Continuous health monitoring and regular condition assessment is of vital importance for engineering structures in general and especially for arch dams. These structures can be exposed to many different loads such as earthquake, blast, wind, ice, and water pressure, which may cause deterioration and loss of structural integrity. Such development may have severe economic consequence and, more importantly, may present a serious risk to public safety. Therefore, the structural behavior of arch dams must be monitored at regular intervals during their service life, although the overall failure rate of these dams is around 1%. Experimental measurements by ambient vibration test methods are among the most commonly preferred inspection techniques for the evaluation of structural performance and safety. The aim of this research is to examine the retrofitting effect on the dynamic properties of a damaged arch dam model, with and without reservoir water, after retrofitting with high-strength structural repair mortar and carbon fiber reinforced polymer composite material. To this end, an arch dam-reservoir-foundation model was built. In the study, ambient vibration tests were carried out for three test-cases to determine changes in dynamic properties, such as natural frequency, mode shape, and damping ratio before and after retrofitting. The three cases were (1)a severely damaged dam with full reservoir (Case-A), (2)a repaired dam with full reservoir (Case-B), and (3)a strengthened dam with full reservoir (Case-C). In addition, all the measurement tests were repeated with an empty reservoir to extract the effect of water. Data for the ambient vibration tests were gathered from the dam body during vibrations by natural excitations. These excitations were provided through small impacts, and the response signals were measured by sensitivity accelerometers placed at the crest points. To obtain the experimental dynamic properties, the enhanced frequency domain decomposition method in the frequency domain was used. Comparisons of experimentally identified dynamic properties for the damaged and the retrofitted dam showed that the retrofitting application affected the structural behavior of the arch dam considerably. It was very effective in restoring the structure's original dynamic properties.
- MakaleYalnız künye2016Dynamic Characteristics of an Arch Dam Model before and after Strengthening with Consideration of Reservoir Water
Altunisik, Ahmet Can; Günaydin, Murat; Sevim, Baris; Bayraktar, Alemdar; Adanur, Suleyman
This technical note presents an investigation about the changing of dynamic characteristics of an arch dam model before and after strengthening considering reservoir water. To this end, an arch dam-reservoir-foundation model has been constructed in the laboratory. Ambient vibration tests have been performed on the damaged and strengthened arch dam models for empty and full reservoir to determine the effect of water on the dynamics characteristics. Enhanced frequency domain decomposition method has been used to extract the dynamic characteristics. Finally, the dynamic characteristics obtained from the damaged and strengthened dam models have been compared to with each other. Also, the natural frequencies for damaged and strengthened models are compared to detect the effect of strengthening application on the frequencies. Results indicate that the natural frequencies and damping ratios are changed with the full reservoir. However, mode shapes are not changed. Results also show that the natural frequencies of damaged dam considerably increase after strengthening applications.
- MakaleYalnız künye2016Logistics center site selection by ANP/BOCR analysis: A case study of Turkey
Peker, Iskender; Baki, Birdogan; Tanyas, Mehmet; Murat Ar, Ilker
Site selection for logistics centers is one of the most strategic decisions in logistics. This study addresses the problem of logistics center site selection, using Analytic Network Process/Benefits, Opportunities, Costs and Risks, which is a multi-criteria decision making technique. The decision problem is applied to the city of Trabzon, which is an important city of the Eastern Black Sea Region in Turkey. First, the results are evaluated in terms of each sub-network and each group and, next, are consolidated for each alternative. They yield that Alternative A is the most appropriate logistics center location of all in Trabzon. Furthermore, the sensitivity analysis results emphasize that the decision model is robust.
- BildiriYalnız künye2016Scheduling of domestic shiftable loads via Cuckoo search optimization algorithm
Cakmak, Recep; Altas, Ismail H.; Cetin, A.; Camurcu, A.Y.
Electrical power systems have been developed to more advanced structures called as smart grids. Among many other issues, demand side management (DSM) is one of the important instruments of the smart grids. DSM techniques increase the efficiency of the grid, and modify consumer's electrical demand via demand response (DR) programs using financial incentives. In this study, shiftable domestic loads scheduled by Cuckoo search algorithm (CSA) to ensure balanced load curve as much as possible while considering the consumers' preferences. The main motivation of this paper is scheduling the usage hours of the shiftable household appliances in a neighborhood by applying the recently developed metaheuristic CSA. This paper proposes an approach to increase the efficiency and lifetime of utility network by scheduling and operating shiftable domestic loads while considering consumer's demand in terms of financial benefits. Proposed CSA based scheduling mechanism is compared with that of Genetic algorithm (GA). The results reveal positive effects of the scheduling and the performance of the CSA over GA.
- BildiriYalnız künye2016Series multiple tuned mass dampers for vibration control of high-speed railway bridges
Kahya, V.; Araz, O.; Zingoni, A.
This paper presents Series Multiple Tuned Mass Dampers (STMDs) in vibration control of railway bridges under the passage of high-speed trains. In solution, the bridge is assumed as a Bernoulli-Euler beam, and the train is simulated as a series of moving forces with constant speed. A classic single TMD, and parallel Multiple TMD(MTMD) devices are also considered for the purpose of comparison. It is assumed that total absorber mass is the same for the devices considered. Optimum absorber parameters are obtained for the criterion based on the minimization of the maximum dynamic displacements of the beam at its midpoint. Control effectiveness and robustness of STMDs are discussed in comparison with other types of absorbers considered.
- MakaleAçık Erişim2016Investigation of pozzolanic activity of volcanic rocks from the northeast of the Black Sea
Çullu, Mustafa; Bolat, Hakan; Vural, Alaaddin; Tuncer, Ertan
Mineralogical and chemical properties, as well as the pozzolanic activities, of the volcanic rocks in the northeast of the Black Sea were examined. Physical and mechanical tests were conducted on samples collected from the study area and the feasibility of using volcanic rocks as pozzolanic admixture in the concrete industry was investigated. Mortar samples containing admixture in the ratios of 0%, 10%, 20%, 30%, 40%, and 50% were prepared by keeping fineness of pozzolanic admixtures fixed. By using these mortar samples, prismatic mortar samples of 4×4×16 cm were prepared and the samples were cured in water. Their 7-, 28-, and 90-day tensile strengths, compressive strengths, and ultrasonic pulse velocity were determined. As a result, it was determined that volcanic rocks can be used to produce blended cement by considering their specific gravity, pozzolanic activities, and compressive strengths. It was noted that increase in trass rate significantly reduced tensile and compressive strength of cement in the early stage as expected.
- MakaleAçık Erişim2015Optimization of electrical power transmission lines' routing using AHP, fuzzy AHP, and GIS
Eroʇlu, Hasan; Aydin, Musa
With the increase of people's need for energy, electrical energy transmission has become a very important issue as well as electrical power generation. One of the most important problems in energy transmission is finding the best route in a very complex study area. To date, many people from different disciplines have come together to find the best routes by manual methods like using paper maps and deciding which route is the least-cost path (LCP) to the destination point. Today it is known that, in engineering problems, and especially in path-finding or site-placing problems, the Geographic Information System (GIS) is the most powerful tool. On the other hand, as finding the best route is a very complicated problem and many criteria should be considered, including slope, landslide, road/railway/pipeline crossing, ice zones, distances to roads, national parks, archaeological areas, residential areas forests, and river crossings, multicriteria decision methods like the analytic hierarchy process (AHP) and fuzzy analytic hierarchy process (FAHP) should be used to make the most accurate decisions. In this study, the AHP and FAHP are used to weight criteria relevant to energy transmission line (ETL) routing. According to the criteria, digital maps of the sample study area are edited, weighted, converted to raster-based format, and gathered using the Environmental Systems Research Institute's ArcGIS Desktop 10 software. After generation of the weighted surface map, the LCP tool is used to find the best route. By selecting different start and end points in the sample study area, accuracy and performance of the best routes according to the LCP algorithm are assessed and some problems of the routes for ETL routing are presented. With this study, mistakes by manual methods will decrease in ETL routing and other routing problems.
- MakaleYalnız künye2015Stochastic seismic analysis of Kömürhan Highway Bridge with varying material properties
Çavdar, Özlem; Bayraktar, Alemdar; Altunışık, Ahmet Can
Stochastic seismic finite element analyses of the Kömürhan Bridge, the material properties of which are described by random fields, are presented in this paper. The stochastic perturbation technique and Monte Carlo simulation (MCS) method are used in the analyses. A summary of MCS and perturbation-based stochastic finite element dynamic analysis formulation of the structural system is given. The Kömürhan Bridge, located on the 51st km of Elazığ-Malatya highway in the east of Turkey, was chosen as a numerical example. The Erzincan earthquake in 1992 was considered a ground motion, since it took place in the vicinity of the bridge. The material properties were considered to be random variables. During the stochastic analysis, displacements and internal forces of the bridge under consideration were obtained using the perturbation-based stochastic finite element method (SFEM), as well as the MCS method. The selected random variables were elastic modulus and mass density. The efficiency and accuracy of the proposed SFEM algorithm were validated through comparison with results of the MCS method.
- MakaleYalnız künye2015CFRP composite retrofitting effect on the dynamic characteristics of arch dams
Altunişik, Ahmet Can; Günaydin, Murat; Sevim, Bariş; Bayraktar, Alemdar; Adanur, Süleyman
The purpose of this study is to investigate the effect of retrofitting dynamic characteristics of a damaged laboratory arch dam model, subsequently repaired with high-strength structural mortar and strengthened with composite carbon fiber reinforced polymer. This study constructed in laboratory conditions is a prototype arch dam-reservoir-foundation model. Five test cases of ambient vibration on the arch dam model illustrate the changes in dynamic characteristics: natural frequency, mode shape, and damping ratio, before and after retrofitting. The ambient vibration tests collected data from the dam body during vibrations by natural excitations which provided small impacts and response signals from sensitivity accelerometers placed at crest points. Enhanced Frequency Domain Decomposition Method in the frequency domain extracts the experimental dynamic characteristics. At the end of the study, experimentally identified dynamic characteristics obtained from all test cases have been compared with each other. Apparently, after the retrofitting, the natural frequencies of the dam body increased considerably, demonstrating that the retrofitting, including repairing and strengthening is very effective on the flashback of initial dynamic characteristics.
- MakaleAçık Erişim2015Static and dynamic responses of Halgavor footbridge using steel and FRP materials
Gunaydin, M.; Adanur, S.; Altunisik, A.C.; Sevim, B.
In recent years, the use of fiber reinforced polymer composites has increased because of their unique features. They have been used widely in the aircraft and space industries, medical and sporting goods and automotive industries. Thanks to their beneficial and various advantages over traditional materials such as high strength, high rigidity, low weight, corrosion resistance, low maintenance cost, aesthetic appearance and easy demountable or moveable construction. In this paper, it is aimed to determine and compare the geometrically nonlinear static and dynamic analysis results of footbridges using steel and glass fiber reinforced polymer composite (GFRP) materials. For this purpose, Halgavor suspension footbridge is selected as numerical examples. The analyses are performed using three identical footbridges, first constructed from steel, second built only with GFRP material and third made of steel-GFRP material, under static and dynamic loadings using finite element method. In the finite element modeling and analyses, SAP2000 program is used. Geometric nonlinearities are taken into consideration in the analysis using P-Delta criterion. The numerical results have indicated that the responses of the three bridges are different and that the response values obtained for the GFRP composite bridge are quite less compared to the steel bridge. It is understood that GFRP material is more useful than the steel for the footbridges.
- MakaleYalnız künye2015Dynamic responses of industrial reinforced concrete chimneys strengthened with fiber-reinforced polymers
Karaca, Zeki; Türkeli, Erdem; Günaydin, Murat; Adanur, Süleyman
Industrial reinforced concrete (RC) chimneys are tall and slender structures that need repair and strengthening in their service lives. Fiber-reinforced polymers (FRPs) are continuously becoming a popular material that is used for strengthening purposes of RC structures. The purpose of this study is to determine the effect of FRP strengthening on dynamic responses of industrial RC chimneys. A 75-m-high industrial RC chimney with an opening on the body was selected for FRP strengthening. First, three-dimensional finite element model of the chimney and its modal analyses were performed in ANSYS software. Then, linear transient analyses of the chimney were carried out by using 1992 Erzincan Earthquake ground motion record. After that, body of chimney was strengthened with FRP composite, and dynamic analyses were performed. Finally, dynamic responses of chimney before and after FRP strengthening, such as displacements and maximum-minimum principal stresses, were compared. At the end of the study, it was seen that displacements increased along the height of the chimney, maximum and minimum principal stresses occurred at the region of opening and base for all analysis, respectively. Also, it was seen from this study that FRP strengthening is effective on the dynamic response of industrial RC chimneys.
- MakaleAçık Erişim2015A low cost outdoor testing facility for detailed photovoltaic device performance characterization
Ogulgonen, Guvenc; Ozden, Talat; Yardim, Ugur; Turan, Rasit; Kincal, Serkan; Turan, R; Gunes, M; Sariciftci, NS; Varlikli, C
Long term outdoor performance monitoring is the ultimate method to capture the long term performance characteristics of PV devices. As time consuming as this process might be, it is the only way in which the local environmental condition versus PV device characteristics may be captured when making investment decisions. This data needs to be captured at least once through the seasonal cycle. It needs to be correlated to the environmental conditions, this monitoring climatic conditions is a requirement. Solar irradiation conditions must be monitored over a range of inclination angles - direct, diffuse and reflected components must be ideally captured separately. The panels must be held at maximum power generating point through the varying illumination conditions. Periodic IV traces must be captured, in addition to the power output to understand mechanisms of degradation, if present. Furthermore, the IV curves must be summarized in terms of relevant performance metrics. This work describes an outdoor testing facility that addresses all the aforementioned requirements. Reliable equipment selections coupled with adequate modelling strategies allow for the generation of a robust and accessible database of performance data.
