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.

Early Diagnosis Behavior in Turkish Women with and without a Family History of Cervical Cancer

Gunaydin, Cansu,Gencturk, Nuran Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2

Background: This study was planned as comparative and descriptive in order to measure and evaluate the knowledge and attitudes regarding early diagnosis of women with and without a family history of cervical cancer. Materials and Methods: The study sample consisted of the relatives of female patients (N=253) who were admitted to Istanbul University of Medicine. Women with a family history of cervical cancer formed the case group, while those without family history of cervical cancer constituted the control group. Two distinct data collection tools, a questionnaire and the Miller Behavioral Style Scale (MBSS), were used in order to obtain data for evaluation with SPSS for Windows 20.0 statistics package program. Results: It was found that 61.0% of the case group with family history of cervical cancer and 19.0% of the control group without family history of cervical cancer were using early diagnostic methods. Thus the presence of an individual with cervical cancer in the family affected the attitudes towards early diagnosis. It was further found that the level of knowledge on cervical cancer and PAP smear test was higher in the case group, which was more sensitive with regard to being informed about cervical cancer as compared to general society. However, the average MBSS scores were not significantly different compared to the control group. Conclusions: It was noted that, women participating this study knowledgeable, but this did not necessarily transform into better behavior.

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.

Synergistic Effect of Fly Ash and Bentonite as Partial Replacement of Cement in Mass Concrete

M. E. Shabab,K. Shahzada,B. Gencturk,M. Ashraf,M. Fahad 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

This research focuses on the effects of using fly ash and bentonite as partial replacement of ordinary Portland cement (OPC) in mass concrete. Replacement of OPC with supplementary cementing materials such as fly ash or bentonite is one of the promising ways to mitigate thermal cracking due to temperature differentials in mass concrete. In this study, three types of concrete mixes with varying amount of partial replacement of OPC were investigated, 25% bentonite, 25% fly ash, and 12.5% bentonite and 12.5% fly ash. These mixtures were named BM, FM and BF, respectively. A fourth control mixture (CM) with no OPC replacement was also studied for comparison purposes. From each mix, one large specimen (having 600 × 800 × 1000 mm overall dimensions) representing mass concrete, and concrete cylinders of standard size representing normal structural concrete were prepared. Various tests were performed on these specimens at ages of 7, 14, 28, 56 and 91 days. Comparatively, BF was the most effective in controlling temperature rise in mass concrete. Moreover, this mix resulted in the highest values of compressive strength at 91 days and higher early-age strength. Ultrasonic pulse velocity (UPV) tests were conducted on mass concrete samples as well as on cores extracted from concrete blocks. Results of these tests revealed that mass concrete blocks made of BF and FM resulted in more uniform properties, or in other words, suffered least from large concrete placement by reducing the heat of hydration.

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.

Effect of Alkali-Silica Reactivity Damage to Tip-Over Impact Performance of Dry Cask Storage Structures

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.