Low velocity impact behavior of concrete beam strengthened with CFRP strip

Erkan Kantar,Özgür Anil 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.3

Nowadays CFRP (Carbon Fiber Reinforced Polymer) became widely used materials for the strengthening and retrofitting of structures. Many experimental and analytical studies are encountered at literature about strengthening beams by using this kind of materials against static loads and cyclic loads such as earthquake or wind loading for investigating their behavior. But authors did not found any study about strengthening of RC beams by using CFRP against low velocity impact and investigating their behavior. For these reasons an experimental study is conducted on totally ten strengthened RC beams. Impact loading is applied on to specimens by using an impact loading system that is designed by authors. Investigated parameters were concrete compression strength and drop height. Two different sets of specimens with different concrete compression strength tested under the impact loading that are applied by dropping constant weight hammer from five different heights. The acceleration arises from the impact loading is measured against time. The change of velocity, displacement and energy are calculated for all specimens. The failure modes of the specimens with normal and high concrete compression strength are observed under the loading of constant weight impact hammer that are dropped from different heights. Impact behaviors of beams are positively affected from the strengthening with CFRP. Measured accelerations, the number of drops up to failure and dissipated energy are increased. Finite element analysis that are made by using ABAQUS software is used for the simulation of experiments, and model gave compatible results with experiments.

The new odd-burr rayleigh distribution for wind speed characterization

Ibrahim Arik,Yeliz M. Kantar,Ilhan Usta 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.6

Statistical distributions are very useful in describing wind speed characteristics and in predicting wind power potential of a specified region. Although the Weibull distribution is the most popular one in wind energy literature, it does not seem to be able to perfectly fit all the investigated wind speed data in nature. Thus, many studies are still being conducted to find flexible distribution for modelling wind speed data. In this study, we propose a new Odd-Burr Rayleigh distribution for wind speed characterization. The Odd-Burr Rayleigh distribution with two shape parameters is flexible enough to model different shapes of wind speed data and thus it can be an alternative wind speed distribution for the assessment of wind energy potential. Therefore, suitability of the Odd-Burr Rayleigh distribution is investigated on real wind speed data taken from different regions in the South Africa. Numerical results of the conducted analysis confirm that the new Odd-Burr Rayleigh distribution is suitable for modelling most of the considered real wind speed cases and it also can be used for predicting wind power.

Estimation of compression strength of polypropylene fibre reinforced concrete using artificial neural networks

R. Tugrul Eredm,Erkan Kantar,Engin Gucuyen,Özgür ANIL 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.5

In this study, Artificial Neural Networks (ANN) analysis is used to predict the compression strength of polypropylene fibre mixed concrete. Polypropylene fibre admixture increases the compression strength of concrete to a certain extent according to mix proportion. This proportion and homogenous distribution are important parameters on compression strength. Determination of compression strength of fibre mixed concrete is significant due to the veridicality of capacity calculations. Plenty of experiments shall be completed to state the compression strength of concrete which have different fibre admixture. In each case, it is known that performing the laboratory experiments is costly and time-consuming. Therefore, ANN analysis is used to predict the 7 and 28 days of compression strength values. For this purpose, 156 test specimens are produced that have 26 different types of fibre admixture. While the results of 120 specimens are used for training process, 36 of them are separated for test process in ANN analysis to determine the validity of experimental results. Finally, it is seen that ANN analysis predicts the compression strength of concrete successfully.

Magnetic Properties of a Mixed Spin-3/2 and Spin-2 Ising Ferrimagnetic System within the Effective-field Theory

Bayram Deviren,Ersin Kantar,Mustafa Keskin 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.6

The magnetic properties of the ferrimagnetic mixed spin-3/2 and spin-2 Ising model with a crystal field in a longitudinal magnetic field on a honeycomb ( = 3) and a square lattice ( = 4) are studied by using the effective-field theory with correlations. The ground-state phase diagram of the model is obtained in a longitudinal magnetic field (h) for a single-ion potential or a crystal-field interaction () plane. We also investigate the thermal variations of the sublattice magnetization, and present the phase diagrams in the (/|J|, kBT/|J|) plane. The susceptibility, internal energy, and specific heat of the system are numerically examined, and some interesting phenomena in these quantities are found due to the applied longitudinal magnetic field. Moreover, the system undergoes first- and second-order phase transitions; hence, the system has a tricritical point. The system also exhibits reentrant behaviors.

Quality of Life and Chemotherapy-related Symptoms of Turkish Cancer Children Undergoing Chemotherapy

Arslan, Fatma Tas,Basbakkal, Zumrut,Kantar, Mehmet Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.3

This cross-sectional and descriptive study was designed to determine symptoms emerging due to chemotherapy treatment and their effects on children's quality of life. The research was carried out between February 2008 and February 2009 at the pediatric oncology clinics in four hospitals, focusing on 93 patients receiving chemotherapy. A survey form, the Pediatric Quality of Life Inventory (PedsQL 4.0) and the Memorial Symptom Assessment Scale (MSAS) were used as data collection tools. Chi-square and Student t tests were performed for data analysis. Some 51.6% of the children were aged 13-15 years old, and 51.8% were boys and 50.5% were diagnosed as having solid tumors. There were significant relations between: antimetabolite chemotherapeutics and feeling irritable and worrying (p=0.001, p=0.030); vinkoalkaloid and numbness/tingling in hands/feet (p=0.043); antracyclines and lack of energy and skin changes (p=0.021, p=0.004); and corticosteroids and lack of appetite, nausea and sadness (p=0.008, p=0.009, p=0.009). Several symptoms such as feeling sad, worrying and feeling irritable caused a significant decrease in the total domain of quality of life scores (p=0.034, p=0.012, p=0.010, respectively). Chemotherapeutic drugs can cause symptoms that can seriously affect quality of life in children.

Vibration measurement and vulnerability analysis of a power plant cooling system

Anil, Ozgur,Akbas, Sami Oguzhan,Kantar, Erkan,Gel, A. Cem Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.11 No.2

During the service life of a structure, design complications and unexpected events may induce unforeseen vibrations. These vibrations can be generated by malfunctioning machinery or machines that are modified or placed without considering the original structural design because of a change in the intended use of the structure. Significant vibrations occurred at a natural gas plant cooling structure during its operation due to cavitation effect within the hydraulic system. This study presents findings obtained from the in-situ vibration measurements and following finite-element analyses of the cooling structure. Comments are made on the updated performance level and damage state of the structure using the results of these measurements and corresponding numerical analyses. An attempt was also made to assess the applicability of traditional displacement-based vulnerability estimation methods in the health monitoring of structures under vibrations with a character different from those due to seismic excitations.

Vibration measurement and vulnerability analysis of a power plant cooling system

Özgür ANIL,Sami Oğuzhan AKBAŞ,Erkan KANTAR,A. Cem GEL 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.2

During the service life of a structure, design complications and unexpected events may induce unforeseen vibrations. These vibrations can be generated by malfunctioning machinery or machines that are modified or placed without considering the original structural design because of a change in the intended use of the structure. Significant vibrations occurred at a natural gas plant cooling structure during its operation due to cavitation effect within the hydraulic system. This study presents findings obtained from the in-situ vibration measurements and following finite-element analyses of the cooling structure. Comments are made on the updated performance level and damage state of the structure using the results of these measurements and corresponding numerical analyses. An attempt was also made to assess the applicability of traditional displacement-based vulnerability estimation methods in the health monitoring of structures under vibrations with a character different from those due to seismic excitations.