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RISS 인기검색어
- 검색키워드
- 저자 : Bora Gencturk (검색결과 4 건)
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Selection of an Optimal Lattice Wind Turbine Tower for a Seismic Region based on the Cost of Energy
Bora Gencturk,Arezou Attar,Cenk Tort 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.7
Over the past few decades, wind has emerged as one of the major sources of green and renewable energy for being a cost effective solution and offering a substantial reduction in greenhouse gas emissions. Currently, onshore wind energy is undergoing a rapid development and expansion at an annual rate of approximately 27%. As such, more and more wind farms are being established in earthquake prone areas resulting from the availability of wind energy in these regions. This paper investigates the optimal selection of lattice wind turbine towers in seismic regions based on the Cost of Energy (COE). Although, various different tower types and materials (e.g., steel and concrete-steel composite monopole) are available, this study focuses on steel lattice towers for providing a cost effective solution and for posing a challenging structural optimization problem. To the knowledge of the authors, design optimization of lattice wind turbine towers subjected to combined earthquake, wind and gravity loading has not been performed before. Ten tower height-wind turbine size combinations are generated by placing turbines with 100 to 400 kW power generation capacity on towers having 24 to 42.6 m height, and a cost optimal solution is obtained for each combination. Taboo search algorithm is used to minimize the total cost. The wind and earthquake loads on the towers are obtained for a specific case study location. The COE for each combination is calculated using three different wind probability distributions. Instead of using simplified structural models, all the details of a rigorous structural analysis, e.g., geometric nonlinearity, are included in the finite element models. Realistic loading conditions, including wind and earthquake, are considered.
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Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Tufail, Muhammad,Shahzada, Khan,Gencturk, Bora,Wei, Jianqiang Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to $650^{\circ}C$ for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
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Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Muhammad Tufail,Khan Shahzada,Bora Gencturk,Jianqiang Wei 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650 『C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
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Masoud Dehghani Champiri,Mir Mohammad Reza Mousavi,Kaspar Jodok Willam,Bora Gencturk 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.3
This paper investigates the effect of concrete degradation due to alkali-silica reactivity (ASR) and its effect on the performance of vertical concrete casks in the case of a hypothetical tip-over event. ASR is one of the major problems in certain concrete structures exposed to high relative humidity and temperature. Using the first order kinetic model, the mechanical and environmental effects of degradation are modeled for a dry-cask storage structure under the conditions that ASR is completely extended. Following the degradation, a tip-over impact simulation was performed and compared with that of an intact cask in terms of failure modes, damage patterns, stresses, and accelerations. It was seen that concrete crushing and shear banding are major failure modes in the cask with intact concrete, but in the case of the ASR affected cask, the concrete is fully damaged and a longitudinal crack which separates the cask into two parts propagates through the outerpack.
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