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Öğe CFRP Strengthening of Reinforced Concrete Frames with Masonry Infill Walls: A Numerical and Parametric Study(TRANS TECH PUBLICATIONS LTD, 2013) Akin, E.; Ozcebe, G.The idea of strengthening the existing masonry infill walls of reinforced concrete (RC) frames has attracted many research groups in the last decade. The use of carbon fiber reinforced polymer (CFRP) strips along the diagonals of infills has become one major technique applied for this purpose. An experimental study conducted by the authors focused on the effect of aspect (height/width) ratio of hollow clay tile infills on the overall response attained by this strengthening methodology. Two different aspect ratios (HCT) were selected in the experimental study. However, a wider range of aspect ratios should also be investigated for design purposes. Therefore, a numerical model of the test frames are developed, which are validated by the experimental response curves. The basics of the numerical model that leads to a parametric study is the subject of this article.Öğe Evaluation of two-center electric field gradient integrals over STOs using elliptical coordinates(SPRINGER, 2008) Akin, E.In this study, analytical expressions are obtained for two different types of two-center EFG integrals and the integrals are calculated using these expressions. Analytical expressions for the integrals are given in terms of auxiliary J and K functions defined by Ozmen et al. [Int. J. Quantum Chem. 91, 13 (2003)] for the evaluation of two-center Coulomb integrals using elliptical coordinates. Results are compared and found to be in good agreement for small quantum numbers with the existing results from the literature. Numerical stability of the proposed method is very good and therefore we also present results for higher quantum numbers, however there is no previous results found in the literature to compare.Öğe Oscillator strengths for singly ionized oxygen(SPRINGER, 2009) Ates, S.; Tekeli, G.; Celik, G.; Akin, E.; Taser, M.The electric dipole oscillator strengths for multiplet and individual lines between some doublet and quartet levels have been calculated using the weakest bound electron potential model theory (WBEPMT) in singly ionized oxygen. We employed both numerical Coulomb approximation (NCA) wave functions and numerical non-relativistic Hartree-Fock (NRHF) wave functions for expectation values of radii in determination of parameters. The calculated oscillator strengths have been compared with available theoretical and experimental results. A good agreement with results in literature has been obtained. Moreover, oscillator strengths not existing in the literature for some highly excited levels have been obtained using this method.Öğe Testing and analysis of infilled reinforced concrete frames strengthened with CFRP reinforcement(SAGE PUBLICATIONS LTD, 2011) Akin, E.; Canbay, E.; Binici, B.; Ozcebe, G.There is an excessive demand for the rehabilitation of frame-type RC buildings which do not satisfy current seismic code provisions. Therefore, it is imperative to develop user-friendly strengthening methodologies which do not necessitate the evacuation of the building during rehabilitation period. The aim of this study was to strengthen the masonry infill walls by means of diagonal carbon fiber-reinforced polymer fabrics and to integrate them with the existing structural frame in order to form a new lateral load resisting system. This study investigated the possible effects of height-to-width ratio of the infills on the overall behavior attained by the previously developed rehabilitation methodology. In the first part of the study, eight 1/3 scaled, one-bay, two-story RC frames with two different aspect ratios were tested. The experimental results in terms of lateral stiffness, strength, drift, and energy dissipation characteristics of the specimens were discussed. In the second part, a numerical study of the frames was conducted to estimate the non-linear behavior of the specimens.Öğe The theoretical calculation of transition probabilities for some excited p-d transitions in atomic nitrogen(SPRINGER, 2006) Celik, G.; Akin, E.; Kilic, H. S.The atomic transition probabilities are calculated for individual lines between some quartet terms of 3p -> 4d and 3p -> 5d transition arrays using weakest bound electron potential model theory (WBEPMT). In the determination of relevant parameters which are needed for calculation of transition probabilities; we employed numerical non-relativistic Hartree-Fock wave functions for expectation values of radius in both ground and excited states unlike to NCA method used on traditional WBEPMT procedure. We have obtained very good agreement between our results and the accepted values taken from NIST.
