The effect of GFRP bars to flexural behaviour in reinforced concrete beams

YÖK Tez ID: 418709Son yıllarda cam elyaf (GFRP) donatılar yüksek dayanımları, düşük özgül ağırlıkları ve korozyona uğramamaları nedeniyle çelik donatılara alternatif olarak kullanılmaktadır. GFRP donatılar göçmeye kadar doğrusal gerilme-şekil değiştirme davranışı göstermektedir. Ayrıca elastisite modülleri çeliğe göre daha düşüktür. Bu nedenlerle bu donatıların davranışlarının iyi anlaşılması, avantaj ve dezavantajların belirlenmesi gerekmektedir. Ülkemizde bu konu ile yapılmış yeteri kadar çalışma mevcut değildir. Bu çalışma çelik donatıya iyi bir alternatif olarak düşünülen GFRP donatılı betonarme kirişlerin davranışlarını tespit etmek ve iyileştirmek amacıyla gerçekleştirilmiş deneysel bir çalışmadır. Çalışmada kiriş çekme donatısı olarak, çelik donatının yanında cam elyaf donatılar da kullanılmıştır. Bu donatılar sadece çelik, sadece cam elyaf, cam elyaf ve çelik donatılar birlikte kullanılacak şekilde düzenlenmiştir. Basınç donatıları ise tüm elemanlarda aynıdır. ½ ölçekli yedi adet betonarme kiriş elemanı hazırlanmış ve eğilme altında test edilmiştir. Deneyler sonunda elemanların süneklik oranları, enerji sönümleme kapasiteleri, akma yükleri ve rijitlikleri değerlendirilmiştir. GFRP donatılar kirişlerin davranışlarının gevrekleşmesine neden olmuş ancak GFRP donatı kullanılan kirişlerin taşıma gücü kapasitesinde çelik donatılı kirişlere göre artış olmuştur.Glass fiber reinforced polymer (GFRP) rebars have been identified as an alternative construction material for reinforcing concrete during the last decade owing to their high stength, low self-weigth and non-corrodible nature. These materials have linear stress-strain behavior up to failure. Furthermore, the modulus of elasticity of GFRP is significantly lower than that of steel. Therefore behavior of GFRP bars should be well understood and it is necessary to determine the advantages and disadvantages of GFRP bars. There are not enough studies about this topic in Turkey. This experimental study is planned for understandign the mechanical properties of GFRP bars that will be used as an alternative to steel bars in future. Steel and GFRP bars were used as tensile reinforcement in beams. Only steel bars, only GFRP bars or steel and GFRP bars together were used as tensile reinforcement in test beams. Steel compression reinforcement was used in all specimes. 7 half scale reinforced concrete beams were tested under four-point bending. After the tests ductility ratio, energy dissipation capacity, yielding load and stiffness values were evaluated. GFRP reinforcement resulted in brittle behaviour in reinforced beams but an increase at ultimate bearing capacity was observed in GFRP reinforced beam compared to steel reinforced beam

Betonerme kirişlerde cam elyaf donatıların eğilme davranışına etkisi

Tez (Yüksek Lisans) -- Kırıkkale Üniversitesi100372

Synthesis of TiB2-reinforced iron-based composite coating

Titanium diboride (TiB2) particulate reinforced Fe-based alloy composite coating was produced with ferrotitaniurn (FeTi), ferroboron (FeB), ferrotungsten (FeW), ferrochromium (FeCr), ferrovanadium (FeV) and ferromolybdenum (FeMo) powders by using gas tungsten arc welding (GTAW) process. The effects of GTAW processing on the microstructure of AISI-4340 alloy coating with ferro-alloy powders were investigated experimentally. Abrasive wear tests were performed on the coated surface of samples to examine the influence of vol% and the size of boride on wear rates. Depending on the results, it was seen that the samples coated by FeTi-FeW-FeB ferro-alloy powders mixture have the highest wear resistance. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved

FeCrC, FeW, and NiAl Modified Iron-Based Alloy Coating Deposited by Plasma Transferred Arc Process

The technique of alloying X120Mn12 steel substrate by plasma transferred arc process was used for development of a surface having high wear resistance. High carbon ferrochromium, ferrotungsten, and nickel-aluminum intermetallic powders were combined to form M7C3 carbides inside Fe-based composite surface coating. The phase transformations on these coated surfaces were comprehensively examined by using a combination of scanning electron microscopy (SEM) with energy dispersive spectrometry microanalysis, differential thermal analysis and X-ray diffraction (XRD). The microstructure studies of the superficial layers of the coating revealed a phase mixture of interdendritic austenite () phase structure and fine eutectic M7C3 carbides. The new formed coated surfaces were investigated by change of alloying elements (Cr, W, Ni), size of dendrites, change of eutectic reaction temperatures, hardness, carbide volume ratio of hard phases, and coating thickness as the processing parameters (powder feed rate and heat input). The dry sliding wear tests were performed on a pin on disc machine. The wear rates of the tests were affected by the powder feed rate, powder type, and applied load. Results revealed that processing powder combination used in this study (FeCrC-FeW-NiAl) provided the best option with superior combination of properties on surface of X120Mn12 steel substrate

A Comparative Examination of Science Achievements in Life Studies Course Curricula Of 2009, 2015 and 2018 According to the Revised Bloom’s Taxonomy: the Case of Turkey

The purpose of this study is to determine the distribution of Science achievements inLife Studies Course Curricula of 2009, 2015 and 2018 regarding the knowledge and cognitiveprocess dimensions of the Revised Bloom Taxonomy and to comparatively examine the resultingdistributions. This study adopted document analysis. While conducting the analysis, we classifiedthe achievements as factual knowledge, conceptual knowledge, operational knowledge and meta-cognitive knowledge in the accumulation of knowledge dimension and as remembering,understanding, applying, solving, evaluating and creating in the cognitive process dimension.Based on our findings, we concluded that achievements of 2009, 2015 and 2018 curricula focusedon remembering, understanding and applying levels in the cognitive dimension and factual andconceptual knowledge dimensions in the knowledge dimension. We present somerecommendations for teachers and teacher candidates, which they can use while preparing theirlesson plans.</p