İnşaat Mühendisliği Bölümü

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Citation - WoS: 11
Citation - Scopus: 15
Assessment of the Effectiveness and the Initial Cost Efficiency of Hot Recycled Asphalt Using Polymer Modified Bitumen
(Elsevier, 2023) Almusawi, Ali; Shoman, Sarmad; Lupanov, Andrei P.
The drastic increase in environmental concerns and increasing costs of road construction materials necessitate evaluating some alternative solutions. One of the most suitable alternatives is recycling old asphalt pavement to produce reclaimed asphalt pavement (RAP). The RAP materials have been commonly combined with asphalt mixtures during pavement construction. Incorporating RAP material should demonstrate an equivalent or better performance than conventional asphalt mixtures. Conversely, the inclusion of RAP mainly needs to improve performance compared to conventional asphalt mixtures. The key issue of using RAP is to restore the loss properties of aged materials and normally asphalt Agent Rejuvenator (ARA) was used. Also, adding polymers with RAP into the asphalt mixture becomes necessary to obtain the required performance. This study investigated the RAP effects of elastomeric polymer on the performance of the asphalt mixture following Russian standards (GOST). The impact of using PMB with RAP material on the asphalt mixture's performance was primarily considered by employing tests that can reveal the adhesion property. Additionally, the performance of the pavement was evaluated in terms of strength and low-temperature cracking. For this purpose, numerous test methods were implemented to appraise the asphalt performance, such as compressive strength, moisture susceptibility, shear resistance, tensile strength, porosity of the mineral particles, and residual porosity. The results indicated that the overall performance of the asphalt mixtures prepared with RAP and combined with polymer depicted a better performance. Moreover, the initial construction cost for each asphalt composition was estimated and compared. The utilization of PMB increased the cost of the asphalt mixture. However, such an increase in the cost would lead to an increase in the overall performance, especially for RAP mixtures.
Citation - WoS: 81
Citation - Scopus: 106
Availibility of Renewable Energy Sources in Turkey: Current Situation, Potential, Government Policies and the Eu Perspective
(Elsevier Sci Ltd, 2012) Kucukali, Serhat; Baris, Kemal
This study aims to explore the availability and potential of renewable energy sources in Turkey as well as assessing related government policies, financial and environmental aspects of renewable energy projects. Turkey is a country which has the highest hydropower, wind and geothermal energy potential among European countries. As a European Union (EU) candidate several incentives were developed in Turkey for electricity generation from renewable energy sources by the enactment of Law No. 5346 in 2005 which was later restructured by Law No. 6094 in 2010. The most important ones are: ease of land acquisition and feed-in-tariffs which promise purchasing of electricity generated and domestic manufacturing of equipment by the private companies with a price of 5.30-9.69 and 0.3-2.55 (sic)c/kWh, respectively, depending on the type of the renewable and the equipment. However, feed-in tariff amounts take reservoir area into account instead of installed capacity for hydroelectric power plants. Moreover, Environmental Impact Assessment (EIA) report is not mandatory for all renewable energy plants. According to the multi-criteria analysis tool developed in this study to evaluate the renewable energy source (RES) technologies the most appropriate renewable energy alternative for Turkey is biomass, simply because of the highest social benefit among others. (C) 2011 Elsevier Ltd. All rights reserved.
Citation - WoS: 12
Citation - Scopus: 16
Debris Flow Modelling and Hazard Assessment for a Glacier Area: a Case Study in Barsem, Tajikistan
(Springer, 2023) Dincer, A. Ersin; Kalpakci, Volkan; Ozturk, Sevki; Yilmaz, Kutay
This study analyses a previous debris flow hazard as a consequence of emerging risks related to climate and regional physical changes. In addition to the increasing flood frequencies, there is an increasing risk of mud or debris flow due to increasing temperature and heavy precipitation resulting in glacier melting. One of the most recent dramatic examples of the debris flow incident took place in Barsem, Tajikistan, in 2015. As a result of heavy precipitation and excess temperature, the melting of glaciers caused debris flow which ended up with a catastrophic damage at Barsem Town. In this study, a methodology for modelling debris flow and related hazard is developed by examining the 2015 incident in detail with a commercially available software, Hydrological Engineering Centre-River Analysis System (HEC-RAS). Simulations and hazard assessment of the incident suggest that assessment of debris flow hazard can be implemented similar to flood hazard. Moreover, it is seen that debris flow inundation area can be predicted accurately by low-resolution free-source digital elevation models (DEMs), while in the present work they could not predict the debris flow hazard assessment accurately. Sensitivity results also reveal that free-source DEMs with higher resolutions do not necessarily give better predictions than free-source DEMs with lower resolutions.
Citation - WoS: 25
Citation - Scopus: 33
Deformation Limits for Structural Walls With Confined Boundaries
(Earthquake Engineering Research inst, 2012) Kazaz, Ilker; Gulkan, Polat; Yakut, Ahmet
For accurate analytical assessment of performance and damage in reinforced concrete members, well-defined deformation limits at particular damage states are required. With advanced and computationally intensive finite element analyses, we establish deformation limits at yield and ultimate limit states for adequately confined rectangular reinforced concrete structural walls in terms of drift ratio, plastic rotation, and curvature. To investigate the deformation limits of structural walls, a parametric study on isolated cantilever wall models is performed. The primary variables of the parametric study are the shear-span-to-wall-length ratio, wall length, axial load ratio, normalized shear stress, the amount of horizontal web reinforcement, and the amount of longitudinal reinforcement at the confined boundary of structural wall models. Expressions and limit values are proposed for yield and ultimate deformation capacity of structural walls, based on the most influential parameters. The proposed equations are found to be promising when compared to results of experiments. [DOI: 10.1193/1.4000059]
Citation - WoS: 22
Citation - Scopus: 26
A Dispassionate View of Seismic-Hazard Assessment
(Seismological Soc Amer, 2013) Gulkan, Polat
Citation - WoS: 48
Citation - Scopus: 63
Ductility of Frp-Concrete Systems: Investigations at Different Length Scales
(Elsevier Sci Ltd, 2013) Lau, Denvid; Tuakta, Chakrapan; Bueyuekoeztuerk, Oral; Gunes, Oguz
Fiber reinforced polymer (FRP) materials have been increasingly used in the last two decades to improve various structural characteristics of reinforced concrete (RC) bridges, buildings and other structures. Ductility of the resulting FRP-concrete system plays an important role in structural performance, especially in certain applications such as earthquake resistant design of structures, where ductility and energy dissipation play a vital role. Wrapping RC columns with FRP has been shown to generally result in significant increase in ductility due to the confinement of concrete by the FRP. Other applications such as flexural strengthening of beams involve tradeoffs between ductility and the desired load capacity. Furthermore, environmental factors may adversely affect the FRP-concrete bond raising concerns about the ductility of the system due to possible premature failure modes. Characterization of these effects requires the use of more involved mechanics concepts other than the simple elastic or ultimate strength analyses. This paper focuses on characterizing ductility of the FRP-concrete systems at different length scales using a combined experimental/computational mechanics approach. Effects of several parameters on ductility, including constituent material properties and their interfaces, FRP reinforcement geometry at the macro- and meso-level, and atomistic structure at the molecular level are discussed. Integration of this knowledge will provide the basis for improved design strategies considering the ductility of FRP-concrete systems from a global as well as local perspective including interface bond behavior under various mechanical and environmental conditions. (C) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 12
Citation - Scopus: 12
Economic and Environmental Impacts of Utilizing Lower Production Temperatures for Different Bitumen Samples in a Batch Plant
(Elsevier, 2022) Almusawi, Ali; Sengoz, Burak; Ozdemir, Derya Kaya; Topal, Ali
The utilization of hot mix asphalt (HMA) for road construction necessitates high temperatures during mixing bitumen and aggregate at asphalt plant. The required (mixing) production temperature is calculated by the standard method (ASTM 2493). The application of this method for polymer modified bitumen (PMB) and warm mix asphalt (WMA) have tendency of higher temperatures. Therefore, some alternative methods suggested by literatures for the determination of production temperature for PMB and WMA have been implemented aiming to determine lower temperatures than the standard method (ASTM 2493). Moreover, the economic impacts of the determined production temperatures through different models are evaluated by the estimation of energy consumption in terms of electricity and natural gas costs for the batch type asphalt plants. Besides, the possible environmental effects are calculated by considering the carbon dioxide emissions. The results of this study have shown that the reduction in production temperatures led to a significant decrease in the total construction cost of each type of asphalt and a significant reduction in the estimated carbon dioxide emission. The results of this study can be used as a reference point for the estimation of both economic and environmental impacts of utilizing lower production temperatures for different bitumen samples.
Citation - WoS: 5
Citation - Scopus: 5
The Effect of Vertical Motions on Damage Accumulation on Concrete Gravity Dams
(Wiley, 2023) Soysal, Berat Feyza; Arici, Yalin; Ay, Bekir Ozer
The effect of vertical ground motions on the seismic response of dams has long been a concern in the seismic design and evaluation of concrete gravity dams. The guidelines regarding the use of vertical motions in time history analysis (THA) are not clear due to the complexity of the effect as well as the large uncertainty in the motion selection process. The goal of this study is to assess the significance of vertical motions' effects on concrete gravity dams considering the relevant variability due to ground motion, system frequency response as well as the shaking level. To this end, a carefully selected ground motion set providing realistic vertical(V)/horizontal(H) loading was used in nonlinear THAs of three different systems with different modal properties. In order to evaluate the intensity of shaking on the vertical motions' effect, the responses were calculated at different seismic levels corresponding to operation, design, and maximum shaking levels. Along with traditional demand parameters commonly employed in assessing seismic response, cracking on the base and at the upstream face of the monolith was adopted as demand measures using a model capable of yielding discrete cracking on the system. The effect of vertical motions was quantified by comparing the response of H + V to H only shaking. The results show the vertical shaking can significantly affect upstream cracking for the operation or design level earthquakes, the effect increasing for larger dams.
Citation - WoS: 24
Citation - Scopus: 27
Evaluation of Soil-Structure Interaction Effects From System Identification of Structures Subject To Forced Vibration Tests
(Elsevier Sci Ltd, 2019) Tileylioglu, Salih; Givens, Michael J.; Mylonakis, George; Stewart, Jonathan P.; Star, Lisa M.
We describe procedures to evaluate the dynamic properties of test structures subject to forced vibration testing. We seek modal vibration periods and damping ratios corresponding to the actual flexible-based response of the structure (incorporating the effects of compliance in the soil medium supporting the foundation) and similar attributes for a fixed-base condition in which only the flexibility of the structure is represented. Our approach consists of using suitable input and output time series with conventional parametric system identification procedures, and as such extends previously developed procedures for use with earthquake recordings. We verify the proposed approach and demonstrate its application using data from two test structures supported on shallow foundations that have been used in forced vibration tests and that have recorded earthquakes. The structures were tested with and without braces to modify their stiffness and were deployed at two sites with different soil conditions. We analyze the results to evaluate experimental period lengthening ratios and foundation damping. The results show (1) strong increases in period lengthening and foundation damping with the wave parameter (dimensionless ratio of structure-to-soil stiffness), (2) compatibility between modal properties from forced vibration testing and earthquake excitation, (3) soil nonlinearity increases period lengthening and modifies foundation damping in a manner that can be reasonably captured in predictive models using equivalent-linear soil properties compatible with a proposed shear strain index.
Citation - WoS: 10
Citation - Scopus: 10
Experimental Investigation of Bonding Behavior of Anchoraged Timber-To Joint
(Springernature, 2021) Ghoroubi, Rahim; Mercimek, Omer; Sakin, Shaimaa; Anil, Ozgur
The comprehensive experimental study examining the general load-displacement behavior, stress distributions and shear stress-shear-displacement behaviors in the connection area when wood structural elements are combined with adhesive or adhesive with mechanical anchorages have been found in very limited number of studies in the literature. Therefore, an experimental study was planned. In this study, the general load-displacement behavior of the timber connection regions which are connected by adhesive and mechanical anchorages together with adhesive, with varying lengths of 180, 240 and 350 mm are investigated experimentally. Besides, the effect of changing the number and location of mechanical anchorages used in the connection area on the general load-displacement behavior and shear stress-shear-displacement behavior was also investigated. Using the load-displacement graphs obtained as a result of the experimental study, a generalized material model is proposed for the shear stress-shear-displacement interfacial adhesion surface for wood-wood junction points. This material model, which is proposed for wood-wood connection points with mechanical anchors, is a model that can be useful and can be used in the analysis of structural systems containing such connections using finite element software. It is thought that the overall capacity and load-displacement behavior of structural systems containing such connection points can be calculated more realistically using the proposed interfacial material model.
Citation - WoS: 21
Citation - Scopus: 20
Experimental Investigation of Damaged Square Short Rc Columns With Low Slenderness Retrofitted by Cfrp Strips Under Axial Load
(Elsevier Science inc, 2020) Ghoroubi, Rahim; Mercimek, Omer; Ozdemir, Anil; Anil, Ozgur
The aim of this study is to develop the retrofitting details, which will increase axial ultimate load capacity, stiffness, displacement ductility ratios, and energy dissipation capacities of short reinforced concrete (RC) low slenderness columns to avoid adverse effects on earthquake performance. The main variables examined in the experimental study are the Carbon Reinforced Fiber Polymer (CFRP) strip width used for retrofitting, the distance between CFRP strips, the use of the anchor at the overlap zone in the CFRP strips, and the placement of the CFRP strips horizontally or vertically to the column axis. For these purposes, eleven square short RC columns with a dimension of 150x150x500 mm (with low slenderness ratio: lambda = 11.5) were produced. The columns were damaged up to 50% of their axial load carrying capacity, then retrofitted with CFRP strips in different ways. The short RC columns with low slenderness ratio were tested under monotonic axial loading until they failure. By obtaining the axial load-displacement graphs of the test specimens, the ultimate axial load capacity, initial stiffness value, displacement-ductility ratios, and energy dissipation capacities are calculated and interpreted. It has been found that the most successful retrofitting detail is obtained when CFRP strips are placed perpendicular to the column axis, and CFRP fan-type anchors are used in the strip overlap region.
Citation - WoS: 78
Citation - Scopus: 91
Finding the Most Suitable Existing Hydropower Reservoirs for the Development of Pumped-Storage Schemes: an Integrated Approach
(Pergamon-elsevier Science Ltd, 2014) Kucukali, Serhat
This study aims to evaluate existing hydropower reservoirs for the development of pumped-storage schemes by using multi-criteria scoring technique. This method enables a screening of existing hydropower reservoirs, in order to assess and rank potential sites for pumped-storage development. This analysis is based on the documented evidence, measured data, and site surveys. The site assessments are categorized in 6 criteria namely geometrical conditions (maximum head, head to water way length ratio, distance to grid connection), geological conditions, environmental, and social conditions. In the context of the study, 7 existing hydropower reservoirs in Turkey, each with a catchment area of more than 50 km(2), are evaluated in order to be utilized as the lower reservoirs of pumped-storage facilities. The overall score of each candidate site is obtained and, their performance is compared. The results indicate that Turkey have suitable existing hydropower reservoirs for the development of pumped-storage facilities. However, the country lacks from legal and market framework for the establishment of pumped-storage power plants. (C) 2014 Elsevier Ltd. All rights reserved.
Citation - WoS: 4
Citation - Scopus: 10
Finding the Most Suitable Existing Irrigation Dams for Small Hydropower Development in Turkey: a Gis-Fuzzy Logic Tool
(Pergamon-elsevier Science Ltd, 2021) Al Bayat, Omar; Maras, H. Hakan; Kucukali, Serhat
This paper enables a screening of existing irrigation dams in order to assess and rank potential sites for small hydropower development by using a Geographic Information System (GIS)-fuzzy logic multi criteria scoring technique. The following criteria are evaluated: dam characteristics (reservoir normal level, reservoir capacity, dam purpose, dam ageing), and grid connection spatial characteristics. The proposed method estimates the suitability degree of each criterion separately and then aggregates them into a Site Suitability Index (SSI). Existing irrigation dams in Turkey are assessed in order to be utilized for hydropower development. The overall score of each candidate site is obtained and, their performance is compared for different strategies. One of the most suitable dams, Karadere, was chosen as a case study. By using the daily continuous monitored data, we showed that flow and head is highly variable during the irrigation season. Accordingly, we evaluated an innovative compact medium-head hydro turbine that can capture those fluctuations with its operational flexibility and minimal civil works. Moreover, an optimal path methodology was applied to find the best grid connection route from the dam to its nearest substation considering the site land use characteristics in order to minimize land expropriation. (c) 2021 Elsevier Ltd. All rights reserved.
Citation - WoS: 39
Citation - Scopus: 45
A Fuzzy Logic Tool To Evaluate Low-Head Hydropower Technologies at the Outlet of Wastewater Treatment Plants
(Pergamon-elsevier Science Ltd, 2017) Kentel, Elcin; Kucukali, Serhat; Ak, Mumtaz
This study aims to find the most sustainable mature Low-Head (LH) hydropower technology option to generate hydroelectricity at the outlet of wastewater treatment plants by assessing the relevant economic, technical, and environmental criteria. A total of six criteria are assessed: investment cost, payback period, energy generation performance, construction duration, fish-friendliness, and aeration capacity. The fuzzy logic tool estimates satisfaction of each criterion separately and then aggregates them into an Overall Performance Index. The proposed method is applied to an existing wastewater treatment plant (Tatlar WWTP) in Ankara, Turkey. For the assessment, the real-time operational data of the plant and the technical drawings are employed. According to the multi-criteria analysis tool developed in this study to evaluate the LW technologies' the most appropriate hydropower technology for the outlet of Tatlar WWTP is found to be the Archimedean screw, because of its superior environmental and economic performance.
Citation - WoS: 29
Citation - Scopus: 32
Investigation of Strengthened Low Slenderness Rc Column by Using Textile Reinforced Mortar Strip Under Axial Load
(Elsevier Sci Ltd, 2022) Mercimek, Omer; Ghoroubi, Rahim; Ozdemir, Anil; Anil, Ozgur; Erbas, Yasar
An experimental and numerical study was conducted to improve the critical performance of low slenderness reinforced concrete columns, such as ultimate load capacity, initial stiffness, and energy dissipation capacity, using Textile-Reinforced Mortar (TRM) strip. A total of 17 reinforced concrete columns were fabricated and tested under uni-axial compression. The effect of carbon textile type, strip width and distance, usage of carbon fiber reinforced polymer (CFRP) fan type anchors was investigated. The experimental part of the study indicated that the ultimate load capacities of reinforced concrete columns strengthened with TRM strips was increased to 1.19-1.78 times. Their initial stiffness increased to 1.01-1.99 times, and energy dissipation capacity values increased to 1.22 and 2.09 times. In addition, simulation models for the experimental specimens were created with the ABAQUS finite element software. Then the results of analyses and the experimental outputs were compared together and interpreted. Finally, using the verified FEM model, a parametric numerical study was carried out to determine the effect of the increase in the concrete compressive strength of the column on the performance of the specimens examined within the scope of the study. According to the main findings of this study, it was demonstrated that the application of the proposed TRM strips for strengthening reinforced concrete columns was a successful method.
Citation - WoS: 22
Citation - Scopus: 26
Measuring Fluid Flow and Heat Output in Seafloor Hydrothermal Environments
(Amer Geophysical Union, 2015) Germanovich, Leonid N.; Hurt, Robert S.; Smith, Joshua E.; Genc, Gence; Lowell, Robert P.
We review techniques for measuring fluid flow and advective heat output from seafloor hydrothermal systems and describe new anemometer and turbine flowmeter devices we have designed, built, calibrated, and tested. These devices allow measuring fluid velocity at high-and low-temperature focused and diffuse discharge sites at oceanic spreading centers. The devices perform at ocean floor depths and black smoker temperatures and can be used to measure flow rates ranging over 2 orders of magnitude. Flow velocity is determined from the rotation rate of the rotor blades or paddle assembly. These devices have an open bearing design that eliminates clogging by particles or chemical precipitates as the fluid passes by the rotors. The devices are compact and lightweight enough for deployment from either an occupied or remotely operated submersible. The measured flow rates can be used in conjunction with vent temperature or geochemical measurements to obtain heat outputs or geochemical fluxes from both vent chimneys and diffuse flow regions. The devices have been tested on 30 Alvin dives on the Juan de Fuca Ridge and 3 Jason dives on the East Pacific Rise (EPR). We measured an anomalously low entrainment coefficient (0.064) and report 104 new measurements over a wide range of discharge temperatures (5 degrees-363 degrees C), velocities (2-199 cm/s), and depths (1517-2511 m). These include the first advective heat output measurements at the High Rise vent field and the first direct fluid flow measurement at Middle Valley. Our data suggest that black smoker heat output at the Main Endeavour vent field may have declined since 1994 and that after the 2005-2006 eruption, the high-temperature advective flow at the EPR 9 degrees 50'N field may have become more channelized, predominately discharging through the Bio 9 structure. We also report 16 measurements on 10 Alvin dives and 2 Jason dives with flow meters that predate devices described in this work and were used in the process of their development. This includes the first advective measurements in the Lau Basin and at the EPR 9 degrees 39.5'N. We discuss potential error sources and how they may affect the accuracy of measurements by our devices and other devices. In particular, we use the turbulent plume theory to evaluate the effect of entrainment of ambient seawater.
Citation - WoS: 10
Citation - Scopus: 13
A Metaheuristic-Guided Machine Learning Approach for Concrete Strength Prediction With High Mix Design Variability Using Ultrasonic Pulse Velocity Data
(Elsevier, 2023) Selcuk, S.; Tang, P.
Assessment of concrete strength in existing structures is a common engineering problem. Several attempts in the literature showed the potential of ML methods for predicting concrete strength using concrete properties and NDT values as inputs. However, almost all such ML efforts based on NDT data trained models to predict concrete strength for a specific concrete mix design. We trained a global ML-based model that can predict concrete strength for a wide range of concrete types. This study uses data with high variability for training a metaheuristic-guided ANN model that can cover most concrete mixes used in practice. We put together a dataset that has large variations of mix design components. Training an ANN model using this dataset introduced significant test errors as expected. We optimized hyperparameters, architecture of the ANN model and performed feature selection using genetic algorithm. The proposed model reduces test errors from 9.3 MPa to 4.8 MPa.
Citation - WoS: 108
Citation - Scopus: 122
Nano-Modification To Improve the Ductility of Cementitious Composites
(Pergamon-elsevier Science Ltd, 2015) Yesilmen, Seda; Al-Najjar, Yazin; Balav, Mohammad Hatam; Sahmaran, Mustafa; Yildirim, Gurkan; Lachemi, Mohamed
Effect of nano-sized mineral additions on ductility of engineered cementitious composites (ECC) containing high volumes of fly ash was investigated at different hydration degrees. Various properties of ECC mixtures with different mineral additions were compared in terms of microstructural properties of matrix, fiber-matrix interface, and fiber surface to assess improvements in ductility. Microstructural characterization was made by measuring pore size distributions through mercury intrusion porosimetry (MIP). Hydration characteristics were assessed using thermogravimetric analysis/differential thermal analysis (TGA/DTA), and fiber-matrix interface and fiber surface characteristics were assessed using scanning electron microscopy (SEM) through a period of 90 days. Moreover, compressive and flexural strength developments were monitored for the same period. Test results confirmed that mineral additions could significantly improve both flexural strength and ductility of ECC, especially at early ages. Cheaper Nano-CaCO3 was more effective compared to nano-silica. However, the crystal structure of CaCO3 played a very important role in the range of expected improvements. (C) 2015 Elsevier Ltd. All rights reserved.
Citation - WoS: 22
Citation - Scopus: 27
Performance Limits for Structural Walls: an Analytical Perspective
(Elsevier Sci Ltd, 2012) Kazaz, Ilker; Gulkan, Polat; Yakut, Ahmet
Recently proposed changes to modeling and acceptance criteria in seismic regulations for both flexure and shear dominated reinforced concrete structural walls suggest that a comprehensive examination is required for improved limit state definitions and their corresponding values. This study utilizes nonlinear finite element analysis to investigate the deformation measures defined in terms of plastic rotations and local concrete and steel strains at the extreme fiber of rectangular structural walls. Response of finite elements models were calculated by pushover analysis. We compare requirements in ASCE/SEI 41, Eurocode 8 (EC8-3) and the Turkish Seismic Code (TSC-07). It is concluded that the performance limits must be refined by introducing additional parameters. ASCE/SEI 41 limits are observed to be the most accurate yielding conservative results at all levels except low axial load levels. It is shown that neither EC8-3 nor TSC-07 specifies consistent deformation limits. TSC-07 suggests unconservative limits at all performance levels, and it appears to fall short of capturing the variation reflected in the calculated values. Likewise EC8-3 seems to fail to represent the variation in plastic rotation in contrast to several parameters employed in the calculation. More accurate plastic rotation limits are proposed. (c) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 45
Citation - Scopus: 51
Risk Assessment of River-Type Hydropower Plants Using Fuzzy Logic Approach
(Elsevier Sci Ltd, 2011) Kucukali, Serhat
In this paper, a fuzzy rating tool was developed for river-type hydropower plant projects, and risk assessment and expert judgments were utilized instead of probabilistic reasoning. The methodology is a multi-criteria decision analysis, which provides a flexible and easily understood way to analyze project risks. The external risks, which are partly under the control of companies, were considered in the model. A total of eleven classes of risk factors were determined based on the expert interviews, field studies and literature review as follows: site geology, land use, environmental issues, grid connection, social acceptance, macroeconomic, natural hazards, change of laws and regulations, terrorism, access to infrastructure and revenue. The relative importance of risk factors was determined from the survey results. The survey was conducted with the experts that have experience in the construction of river-type hydropower schemes. The survey results revealed that the site geology and environmental issues were considered as the most important risks. The new risk assessment method enabled a Risk Index (R) value to be calculated, establishing a 4-grade evaluation system. The proposed risk analysis will give investors a more rational basis to make decisions and it can prevent cost and schedule overruns. (C) 2011 Elsevier Ltd. All rights reserved.

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