Behavior of FRP-confined normal- and high-strength concrete under cyclic axial compression

An important application of fiber-reinforced polymer (FRP) composites is as a confining material for concrete, both in the seismic retrofit of existing reinforced concrete columns and in the construction of concrete-filled FRP tubes as earthquake-resistant columns in new construction. The reliable design of these structural members against earthquake-induced forces necessitates a clear understanding of the stress-strain behavior of FRP-confined concrete under load cycles. This paper presents the results of an experimental study on the behavior of FRP-confined normal- and high-strength concrete under axial compression. A total of 24 aramid and carbon FRP-confined concrete cylinders with different concrete strengths and FRP jacket thicknesses were tested under monotonic and cyclic loading. Examination of the test results has led to a number of significant conclusions in regards to both the trend and ultimate condition of the axial stress-strain behavior of FRP-confined concrete. These results are presented, and a discussion is provided on the influence of the main test parameters in the observed behaviors. The results are also compared with two existing cyclic axial stress-strain models for FRP-confined concrete. © 2012 American Society of Civil Engineers.Togay Ozbakkaloglu and Emre Aki

İlklerin piyanisti İdil Biret'in Türk ve dünya müziğine katkısı ve Türk müzk eğitimine etkisi

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2018.This work is a student project of the Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.The History of Turkey course (HIST200) is a requirement for all Bilkent undergraduates. It is designed to encourage students to work in groups on projects concerning any topic of their choice that relates to the history of Turkey. It is designed as an interactive course with an emphasis on research and the objective of investigating events, chronologically short historical periods, as well as historic representations. Students from all departments prepare and present final projects for examination by a committee, with 10 projects chosen to receive awards.Includes bibliographical references (pages 13-14)by Fatma Özden Mercan

Phosphorus-nitrogen compounds. Part 42. the comparative syntheses of 2-: Cis -4-ansa(N/O) and spiro(N/O) cyclotetraphosphazene derivatives: Spectroscopic and crystallographic characterization, antituberculosis and cytotoxic activity studies

The reaction of N4P4Cl8 (1) with one equimolar amount of the sodium salt of an N/O donor-type bidentate ligand (2) afforded two kinds of derivatives, namely, mono-ferrocenyl-2-cis-4-dichloro-ansa- (2,4-ansa; 3) and mono-ferrocenyl-spiro- (spiro; 4) hexachlorocyclotetraphosphazenes. The reaction yield (35%) of 4 was significantly larger than that of 3 (14%). The 2,4-ansa compound (3) was reacted with excess secondary amines to produce 2-cis-4-dichloro-ansa-cyclotetraphosphazenes (3a-3d). On the other hand, the spiro compound (4) gave fully substituted mono-ferrocenyl-spiro-cyclotetraphosphazenes (4a-4d) with excess monoamines as well. The tetrameric phosphazene derivatives were characterized by ESI-MS and/or HRMS, FTIR, HSQC, HMBC, 1H, 13C, and 31P NMR spectroscopy and X-ray crystallography (for 4). It is observed that the 2,4-ansa and spiro-cyclotetraphosphazenes have different thermal stabilities. Additionally, the CVs of the new mono-ferrocenyl pendant-armed cyclotetraphosphazenes revealed electrochemically reversible one-electron oxidation of the Fe-redox centre. The 2,4-ansa phosphazenes (3 and 3a-3d) have two different stereogenic P centers indicating that they are expected to be in racemic mixtures (RR?/SS?). The chiralities of 3a and 3c were investigated by chiral HPLC. The manuscript also deals with the antimicrobial activities against G(+)/G(-) bacteria and fungi, the interactions with plasmid DNA, the in vitro cytotoxic activities against L929 fibroblast and MCF7 breast cells, and the antituberculosis activities against Mycobacterium tuberculosis H37Rv of the cyclotetraphosphazenes. © 2019 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Hacettepe Üniversitesi: 013 D04 602 004Türkiye Bilimler AkademisiTürkiye Bilimsel ve Teknolojik Araştirma Kurumu, TÜBITAK: 215Z496The authors thank the ‘‘Scientific and Technical Research Council of Turkey’’ (Grant No. 215Z496). T. H. is grateful to Hacettepe University Scientific Research Project Unit (Grant No. 013 D04 602 004), and Z. K. thanks the Turkish Academy of Sciences (TÜBA) for partial support of this work