Orientador: Arai Augusta Bernardez Pecora / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T19:26:31Z (GMT). No. of bitstreams: 1 Arini_RicardoGreber_M.pdf: 5502572 bytes, checksum: c19e6a830ce67a88c8959a10cd21aef8 (MD5) Previous issue date: 2008 / Resumo: Este trabalho teve como objetivo analisar experimentalmente um sistema de refrigeração por compressão de vapor operando com o hidrocarboneto propano (R290) em substituição ao refrigerante HCFC22, visando atender as necessidades do mercado atual de refrigeração comercial, que busca alternativas que atendam à exigência de substituição gradual dos refrigerantes hidroclorofluorcarbonados (HCFC's). O estudo foi realizado em um mini-tanque de resfriamento de leite, produzido comercialmente para operar com o refrigerante 22. Foram analisadas as influências da temperatura do fluido no interior do tanque e da temperatura do ar de resfriamento do condensador sobre parâmetros de desempenho do ciclo de compressão como: pressão de condensação, pressão de evaporação, coeficiente de desempenho, efeito frigorífico, trabalho de compressão, taxa específica de transferência de calor no condensador, temperatura do refrigerante na descarga do compressor e volume específico do refrigerante na aspiração do compressor. Além da análise energética, este trabalho apresenta a análise exergética do ciclo operando com R290 em comparação com o ciclo operando com R22. As medidas experimentais foram realizadas em condições de regime permanente, verificado quando não se observaram variações significativas na temperatura do refrigerante em diversos pontos do ciclo. A temperatura do fluido do tanque e a temperatura do ar de resfriamento do condensador foram mantidas constantes através de resistências elétricas imersas na água contida no tanque e na entrada do condensador, respectivamente. A análise de resultados mostrou que é possível a substituição do refrigerante R22 pelo R290 no sistema estudado, sendo observado que o sistema operando com R290 apresentou desempenho energético equivalente ao apresentado pelo R22. Foi verificado que a eficiência exergética do sistema operando com R290 foi igual ou superior à obtida com R22. Observou-se ainda um menor consumo de energia elétrica pelo sistema nos testes de resfriamento utilizando propano como refrigerante. / Abstract: In order to meet the requirements of the commercial refrigeration market, which demands for alternatives to substitute gradually the use of refrigerants such as hydroclorofluorcarbons (HCFC's), this research had the aim to analyze experimentally a mechanical vapor-compression refrigeration system operating with hydrocarbon propane (R290) as an alternative for R22. This study was made in a small tank for milk refrigeration, commercially built to operate with the refrigerant HCFC22. It was analyzed the influences of the factors: temperature of the water inside the tank and temperature of the cooling air at the entrance of the condenser, on the performance of the compression cycle. The following parameters were determined: evaporating pressure, condensing pressure, coefficient of performance, refrigeration capacity per unit mass of refrigerant flow, compression work, rate of heat transfer per unit mass of refrigerant flow at the condenser, refrigerant discharge temperature at the compressor outlet and specific volume of the refrigerant at the compressor inlet. In order to verify which refrigerant fluid realizes the best usage of the available work, it was made, besides an energetic analysis, a comparative exergetic analysis of the cycles. The experimental measures were made at steady state conditions, verified when no significant variations of refrigerant temperatures in several parts of the cycle were observed. The water temperature inside the tank and the air temperature, at the entrance of the condenser, were kept constant by using electrical resistances. The analysis of the results showed that R290 could be used as a substitute for R 22 to the studied system. It was observed that the energetic performance of the system working with R290 was better than the obtained using R22. The exergetic efficiency of the system using R290 was equal or greater than that obtained using R22. A less electrical energy consumption was obtained in the cooling experiments using R290 as refrigerant. / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Orientador: Fabio Husemann Menezes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T03:12:56Z (GMT). No. of bitstreams: 1 Rielli_Glauber.pdf: 567843 bytes, checksum: 4d042894d00f11bcc831e52dc91eb94b (MD5) Previous issue date: 2009 / Resumo: Objetivo: Avaliar em suínos a viabilidade, morbidade e mortalidade imediata do acesso vascular alternativo para hemodiálise através da punção da veia ázigos, guiada por vídeo-toracoscopia. Material e métodos: Oito suínos foram submetidos a punção da veia ázigos e posterior introdução do cateter de hemodiálise na posição central através de vídeo-toracoscopia em hemitórax esquerdo, com ligadura distal e reparo proximal da mesma com dupla laçada de fio de silicone para hemostasia para quando da retirada do cateter. Os animais foram monitorizados através de dados hematimétricos, gasometria, pressão invasiva e sacrificados ao final. Resultados: Em cinco animais o procedimento transcorreu semintercorrências, com fluxo adequado pelo cateter, sem hemorragia, em um tempo médio de duas horas. Em dois animais houve a necessidade de dissecção direta da veia ázigos através da conversão para toracotomia devido a perda do controle hemostático. Em um destes animais houve lesão do parênquima pulmonar sem comprometer a ventilação. Em um animal a veia não foi localizada por provável lesão na inserção do trocar. Não ocorreram óbitos durante o procedimento. Conclusão: A técnica se mostrou viável, mas com complicações técnicas relacionadas ao treinamento, tendo o potencial de ser utilizado como acesso venoso alternativo para hemodiálise. Outros estudos podem validar estes achados com o intuito de se utilizar em humanos sem acesso vascular para hemodiálise / Abstract: Purpose: The purpose of this acute experiment is to evaluate in the pigs the feasibility and immediate complications associated with the transpleural cannulation of the azygos vein performed under video-thoracoscopy. Material and Methods: Eight female pigs were submitted to central venous cannulation of the azygos vein guided by vodeo-thoracoscopy of the left side of the thorax. The azygos vein was ligated distally and secured proximally with a double silicone strand loop, intended to be used as bleeding control in case the catheter is withdrawn. Invasive blood pressure with hematimetric and gasometrical data was recorded during the procedure. All animals were sacrificed after the experiment. Results: All animals survived the experiment. There were five successful cannulations. There were two conversions to thoracotomy because of bleeding which, even if minor, hindered the view of the operation field and were successfully converted to thoracomy with direct cannulation of the vein. There was one lung injury caused by a retractor. There was one termination of the procedure because the azygos vein was not found probably because of a lesion during the trocar insertion. Conclusion: In conclusion, the video-thoracoscopic technique was found to be feasible with complications related to technical training and could become an alternative access in patients with unsuitable conventional central venous access. Further investigation could validate these findings / Universidade Estadual de Campi / Ciencias Medicas / Mestre em Cirurgia

Gamification could be a solution to make office work more productive by in- creasing the intrinsic motivation of employees. Currently, little research exists on gamification in connection to administrative tasks. In literature the im- portance of designing gamified tasks to the target group is stressed. This study explores in an experiment the impact of gamification on intrinsic motivation while conducting basic administrative tasks, as well as differences between age groups. The qualitative analysis of the experiment (n = 32) reveals indications that gamification triggers positive emotions, a higher engagement and creativi- ty. Using a mixed methods approach, the indications from the qualitative anal- ysis could not be proven quantitatively with a statistical significance. The re- sults further suggest, that people over 35 years tend to perceive gamification more extreme than younger ones, leading to either high intrinsic motivation or alienation.

This essay presents a study of retention of idioms delving into a pedagogical approach by presenting them to a group of lower secondary students. The study also explores students’ memory retention whilst concurrently investigating if certain types of idioms are retained to a greater extent than others. For the sake of assessing memory retention in relation to these various types of idiomatic transparency, the selected idioms have been divided into three separate categories; transparent, semi-transparent and opaque depending on their literal and figurative meaning. This essay argues that opaque idioms are retained to a lesser extent in memory due to their non-transparent metaphorical meaning. In fact, the most striking finding is that idioms pertaining to the opaque category are indeed more difficult for students to learn and are also forgotten the fastest. Previous research has put emphasis on the complex structure of idioms and opinions seem divided regarding to what extent the teaching of idioms should be implemented together with other vocabulary items in a classroom setting. On the other hand, the same research emphasizes the great value of idioms; potentially expanding student vocabulary and making the English language more nuanced and native-like.

[EN] Climate change is one of the short term threats for the humanity because it can affect seriously to the environment and, consequently, to vegetal and animal life. If it is not stopped in next years, maybe this effect will be irreversible. Climate change is produced by anthropogenic emissions of Greenhouse Gas to Earth's atmosphere. Vapour compression systems are one of the main contributors to this phenomenon. Among them, commercial refrigeration applications, through HFC usage, can be highlighted. Since 1990s, developed countries supermarkets are using refrigerants (mainly R134a, R404A and R507A) with great impact (high GWP values) on the climate change due to leakages, especially from parallel compressor rack DX systems. Recently, some regulations and directives have been approved to limit GWP values of HFC used in most extended refrigeration and air conditioning applications, directly affecting to commercial refrigeration. In this thesis, some low-GWP alternatives to replace the most commonly used HFC refrigerants in commercial refrigeration are evaluated, taking into account the limitations imposed by these regulations. To carry out this evaluation, the current status of parallel compressor rack refrigeration systems and their fluids has been reviewed. Then, the different low-GWP options to replace R134a and R404A have been studied. HFOs and their mixtures with HFC have been highlighted as the most promising drop-in or retrofit alternatives. Thus, R1234yf, R1234ze(E) and R450A were proposed to replace R134a and R448A to substitute R404A. The theoretical performance of the different low-GWP alternative fluids, as an overview of their potential use, has been studied at typical parallel compressor rack refrigeration operating conditions using the basic thermodynamic vapour compression cycle. Given the good theoretical performance of these refrigerants, they have been tested in a vapour compression test bench. From the experimental results it is depicted that R1234yf and R1234ze(E) are not acceptable as drop-in or light retrofit refrigerants from an energetic point of view. These fluids, when used in R134a systems, require system modifications (more severe in the case of R1234ze(E)) to achieve acceptable energy efficiency values. Moreover, due to the large refrigerant charge in PCRRS, both HFOs could present problems relating to security. Thus, while R450A presents a GWP value of 547, it appears as the best option to replace R134a due to the similar energy efficiency and properties. Its experimental mass flow rate and cooling capacity are slightly lower than R134a, but the final COP is approximately the same. The best R450A results when compared to R134a are obtained at higher CRs. Although can obtain better efficiency results in new systems, with a minor TXV adjustment R448A shows very high performance when it is used in R404A systems. Despite R448A lower cooling capacity than that R404A, this HFC/HFO mixture can achieve great CO2 equivalent emission reductions and it is recommended as lower-GWP replacement for R404A. / [ES] El cambio climático es una amenaza para la humanidad ya que puede afectar seriamente al medio ambiente y, en consecuencia, a la vida animal y vegetal. Si en los próximos años no se actúa para detenerlo, tal vez este efecto sea irreversible. Entre otros factores, el incremento de la temperatura global es producido por las emisiones antropogénicas de gases de efecto invernadero a la atmósfera. La refrigeración comercial, basada en sistemas de compresión de vapor, contribuye de forma relevante a este fenómeno a través del uso de fluidos sintéticos como refrigerantes y del consumo de energía eléctrica procedente de combustibles fósiles. Desde la última década del siglo XX, los supermercados de países desarrollados utilizan HFCs como fluidos de trabajo, principalmente R134a, R404A y R507A. Estos gases, de alto potencial de calentamiento atmosférico (PCA), contribuyen al cambio climático al fugarse accidentalmente de los sistemas de refrigeración, destacando las centrales de compresores en paralelo conectadas a sistemas de expansión directa. El valor máximo de PCA de los HFCs utilizados en aplicaciones de refrigeración y aire acondicionado va a ser controlado por normativas comunitarias, afectando directamente a los fluidos usados comúnmente en refrigeración comercial. Esta tesis evalúa diferentes alternativas de bajo PCA para sustituir los refrigerantes HFC más utilizados en refrigeración comercial, teniendo en cuenta las limitaciones impuestas por las normativas actuales. Para llevar a cabo dicho estudio, se revisa el estado actual de los sistemas de centrales de compresores en paralelo y sus fluidos. A continuación, se analizan las diferentes opciones de bajo PCA para sustituir al R134a y R404A. Al destacar los HFOs y sus mezclas con HFCs como alternativas para realizar un reemplazo con pocas modificaciones del sistema (propiedades similares); R1234yf, R1234ze(E) y R450A son propuestos para sustituir al R134a y R448A para R404A. El rendimiento teórico de los diferentes fluidos alternativos de bajo PCA, para obtener una visión general del potencial de su uso, se estudia simulando las condiciones operativas típicas de las centrales de compresores en paralelo, usando el ciclo termodinámico de compresión de vapor básico. Dado el buen rendimiento mostrado por estos refrigerantes, son ensayados en un banco de pruebas de compresión de vapor. De los resultados experimentales se observa que R1234yf y R1234ze(E) no son aceptables desde un punto de vista energético como sustitutivos directos o con menores modificaciones. Dichos fluidos, cuando son utilizados en sistemas de R134a, requieren modificaciones del sistema (más severas en el caso del R1234ze(E)) para alcanzar valores aceptables de eficiencia energética. Por otra parte, debido a la gran carga necesaria en PCRRS, ambos HFOs podrían presentar problemas en cuanto a la seguridad. Así, mientras que el R450A presenta un valor de PCA de 547, aparece como la mejor opción para sustituir al R134a debido a una eficiencia energética y propiedades similares. El caudal másico y la capacidad frigorífica del R450A son ligeramente inferiores en comparación con las del R134a, pero por otra parte, el COP resultante es aproximadamente el mismo. Los mejores resultados obtenidos para R450A son obtenidas a altas tasas de compresión. Aunque puede ser obtenida una eficiencia energética más alta en sistemas de nuevo diseño, con sólo un ajuste menor de la válvula de expansión termostática, el R448A muestra valores muy altos de rendimiento en sistemas utilizados con R404A. A pesar de que la capacidad frigorífica del R448A es menor que la del R404A, esta mezcla de HFC y HFO puede dar lugar a grandes reducciones de emisiones de CO2 equivalentes, siendo así recomendado como reemplazo del R404A con menor PCA. / [CA] El canvi climàtic és una amenaça per a la humanitat ja que pot afectar seriosament el medi ambient i, en conseqüència, la vida animal i vegetal. Si en els propers anys no s'actua per aturar-lo, potser aquest efecte siga irreversible. Entre altres factors, l'increment de la temperatura global és produït per les emissions antropogèniques de gasos d'efecte hivernacle a l'atmosfera. La refrigeració comercial, basada en sistemes de compressió de vapor, contribueix de manera rellevant a aquest fenomen per l'ús de fluids sintètics com refrigerants i pel consum d'energia elèctrica procedent de combustibles fòssils. Des de l'última dècada del segle XX, els supermercats dels països desenvolupats utilitzen HFCs com fluids de treball, principalment R134a, R404A i R507A. Aquests gasos, d'alt potencial d'escalfament atmosfèric (PCA en castellà), contribueixen al canvi climàtic quan s'escapen accidentalment dels sistemes de refrigeració. D'aquest tipus de sistemes destaquen com a grans emissors de diòxid de carboni les centrals de compressors en paral·lel connectades a sistemes d'expansió directa. El valor màxim de PCA dels HFCs utilitzats en aplicacions de refrigeració i aire condicionat serà controlat per normatives comunitàries, cosa que afectarà directament els fluids utilitzats a la gran majoria de sistemes de refrigeració comercial. Aquesta tesi avalua diferents alternatives de baix PCA per substituir els refrigerants HFC més utilitzats en refrigeració comercial sense oblidar les limitacions imposades per les normatives actuals. Per dur a terme aquest estudi, es revisa l'estat actual dels sistemes de centrals de compressors en paral·lel i els seus fluids. A continuació, s'analitzen les diferents opcions de baix PCA per substituir l'R134a i l'R404A. Els HFOs i les seves mescles amb HFCs com alternatives destaquen per permetre una substitució amb poques modificacions del sistema (propietats similars); R1234yf, R1234ze(E) i R450A són proposats per substituir l'R134a i R448A per l'R404A. Per obtenir una visió general del potencial de l'ús dels diferents fluids alternatius de baix PCA, s'estudia el seu rendiment teòric mitjançant una simulació de les condicions operatives típiques de les centrals de compressors en paral·lel. Per a aquesta simulació s'empra el cicle termodinàmic de compressió de vapor bàsic. Com a conseqüència del bon rendiment mostrat per aquests refrigerants, són assajats en un banc de proves de compressió de vapor. Dels resultats experimentals s'observa que R1234yf i R1234ze(E) no són acceptables des d'un punt de vista energètic com a substitutius directes o amb menors modificacions. Aquests fluids, quan són utilitzats en sistemes de R134a, requereixen modificacions del sistema (més severes en el cas de l'R1234ze(E)) per assolir valors acceptables d'eficiència energètica. D'altra banda, a causa de la gran càrrega necessària en PCRRS, tots dos HFOs podrien presentar problemes en temes de seguretat. Així, mentre que el R450A presenta un valor de PCA de 547, apareix com la millor opció per substituir l'R134a a causa de una eficiència energètica i propietats similars. El cabal màssic i la capacitat frigorífica de l'R450A són lleugerament inferiors en comparació amb les de l'R134a, però d'altra banda, el COP resultant és aproximadament el mateix. Els millors resultats de l'R450A són obtinguts a altes taxes de compressió. Tot i que pot ser obtinguda una eficiència energètica més alta en sistemes de nou disseny, amb només un ajust menor de la vàlvula d'expansió termostàtica, l'R448A mostra valors molt alts de rendiment en sistemes utilitzats amb R404A. Encara que la capacitat frigorífica de l'R448A és menor que la de l'R404A, aquesta barreja de HFCs i HFO pot aconseguir grans reduccions d'emissions de CO2 equivalents, i es per tant es recomanada com a reemplaçament amb menor PCA de l'R404A. / Mota Babiloni, A. (2016). ANALYSIS OF LOW GLOBAL WARMING POTENTIAL FLUORIDE WORKING FLUIDS IN VAPOUR COMPRESSION SYSTEMS. EXPERIMENTAL EVALUATION OF COMMERCIAL REFRIGERATION ALTERNATIVES [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62680 / TESIS / Premios Extraordinarios de tesis doctorales

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Spillways are hydraulic structures that allow dams to release and convey surplus water or flood from the reservoir to the downstream channel. The spillway is a safety structure that prevents the overtopping of the dam. Many dam failure disasters were due to the inadequate capacity of the spillway, which fully illustrates the prominence of spillway design. According to the control structure, spillways can be divided into gated and ungated type. The gated spillway provides better control of the managed water level and reduces the elevation of the top of the dam. Researchers have mostly used experimental models to investigate these two types of spillways in previous literature. In the past few years, following the rapid development of numerical simulation technology, there have been more studies on the numerical modeling of spillways. However, most of the literature was about ungated spillways and most of it considered the case of low head ratios, while the case with gates, especially the case of vertical plane gates, was less investigated. In this study, the hydraulic characteristics, such as velocity, pressure, and discharge coefficient, of the ungated and gated ogee spillways are investigated by means of physical and numerical models for the case of low and high head ratios. The study covered head ratios varying from 1.4 to 4.6 and the relative gate-openings varying from 0.5 to 2. The second main objective of this study was to evaluate the performance of the numerical model to simulate gated and ungated spillways. It mainly employed 2DV OpenFOAM to simulate three turbulence models (realizable k-ε, RNG k-ε, k-ω SST), and the results were compared and calibrated with the experimental results from the physical model tests performed by the author to verify the performance of the numerical model. This study aims to demonstrate that the numerical model can be used as a complementary tool to the physical model to measure the hydraulic performance of ogee spillways.

Syfte: Målsättningen med studien är att hos friska kvinnor utvärdera om intensiv tuggning leder till en proprioceptiv allodyni i massetermuskulaturen. Följande hypoteser testades i studien: 30 minuters intensivt tuggande leder till (1) ökad trötthet och smärta, (2) sänkt smärttröskel, (3) ökad vibrotaktil känslighet (4) samt träningsvärk i massetermuskulaturen bilateralt. Material och Metod: 16 friska kvinnor (medelålder 25.8 ± 5.0 år) deltog i studien som bestod av två 60-minuters sessioner med 24-timmars uppföljning. Vid ena sessionen tuggade försökspersonerna på ett grekiskt tuggummi (Masticha Chios) i 5-minuters intervaller under 30 minuter, och vilade vid den andra sessionen. En vibrameter användes för att mäta vibrationströskel, upplevd vibrationsintensitet och upplevd vibrationsobehag. Upplevd trötthet och upplevd smärtintensitet värderades enligt en visuell analog skala 0-100 mm (VAS skala). Smärttröskeln mättes med en algometer som applicerades på massetermuskelns fäste. Två vägs variansanalys användes för att testa utfallsvariabler för upprepade mätningar och Dunnett’s posthoc-test. Resultat: En signifikant skillnad kunde ses mellan tuggning och icke tuggning för vibrationströskeln (P < 0.001); upplevda tröttheten (P < 0.001); smärttröskeln (P < 0.01); upplevda vibrationsobehaget (P < 0.05). Inga signifikanta skillnader observerades för upplevd smärta och upplevd vibrationsobehag. Däremot kunde en signifikant ökning ses över tid för vibrationströskeln och den upplevda tröttheten. Konklusion: Våra fynd indikerar att det ej finns något samband mellan intensiv tuggning och träningsvärk i massetermuskulaturen. Däremot resulterade tuggningen i ökad muskeltrötthet och vibrationsobehag, samt signifikant högre trösklar för smärta och vibration under försökets gång. Proprioceptiv allodyni kunde ej påvisas. / Aims: To evaluate if intense chewing leads to proprioceptive allodynia in the masseter muscle, and test if (1) pain and fatigue are increased after intense chewing, (2) pressure pain thresholds are decreased after intense chewing, (3) vibration thresholds are increased after intense chewing, (5) intense vibrations exacerbate pain after intense chewing. Materials and Methods: 16 healthy female volunteers (mean age 25.8 ± 5 years) participated in two 60-minute sessions, each with 24-hour follow-ups. In the first session, the subjects were instructed to chew on a viscous chewing gum (Masticha Chios). In the other session the participant were assigned a control task where no chewing was performed. Perceived intensity of vibration and perceived discomfort were assessed with a Vibrameter® on a 0-50-100 visual analog scale (VAS). Two 0-100 mm visual analog scales measured pain intensity and perceived fatigue. The pain threshold was measured with an electronic algometer. These variables were measured to assess delayed onset muscle soreness. All measurements were made on the masseter muscles. Two-way analysis of variance for repeated measures and Dunnett’s post hoc test was used to test for significant alterations in the outcome variables. Results: Significant differences were observed between chewing and no-activity for vibration threshold (P<0.001); perceived fatigue (P<0.001); pain threshold (P<0.01) and vibration discomfort (P<0.05). No significant differences were seen for perceived pain and perceived intensity of vibration. A significant increase over time could only be observed for vibration threshold (P<0.01) and perceived fatigue (P<0.05). Conclusion: Our findings suggest that there is no relation between intense chewing and delayed onset muscle soreness in the masseter muscles. Intense chewing evoked moderate levels of fatigue and discomfort, and a hypoalgesia to mechanical stimulation, and reduced vibrotactile sensitivity.

Helical heating coils are widely used in most conventional electric stoves for many years, these heating coils can reach 600-700°C, which is higher than the ignition point of oil and grease (about 400°C), leading to many fires. Pioneering Technology Inc. has developed a Safe-T Element plate to address such problem. The Safe-T Element plate is manufactured from Gray Cast Iron. However, these plates deform during its use. This study was carried out to investigate the current Safe-T Element design, both experimentally and numerically, in order to determine the root causes behind the deformation problem of the plate, and to suggest changes to the existing design in order to limit its distortion to acceptable targets. A chemical analysis was carried out to establish the type of material of the Safe-T Element plate. Chemical analysis showed that the material of the plate is cast iron. The microstructure of the plate was tested in order to examine its type and homogeneity. Tensile testing was carried to establish the grade of the material, and to calculate the value of its young's modulus and yield strength. Tensile testing indicated that the material of the Safe-T Element plate is close to Gray Cast Iron Class 40. Differential scanning calorimetry testing was carried out to investigate thermal stability of the plate material. This test indicated that material is thermally stable. Thermal cycling testing indicated that the root cause of the deformation problem is elastic thermal buckling. Temperature uniformity tests were carried out. More than 100°C temperature variation in the radial direction was observed. To address the distortion of the plate, an optimum geometry has been suggested based on the findings of the numerical investigation by removing the outer ring from the original design of the plate. / Thesis / Master of Applied Science (MASc)

The present research is conducted to investigate the behaviour of elliptical tube columns filled with self-compacting concrete (SCC). In total, ten specimens, including two empty columns, were tested to failure. The main parameters investigated were the length and the sections of the columns, and the concrete compressive strength. Artificial Neural Network (ANN) model was developed to predict the compressive strength of SCC using a comprehensive database collected from different previous studies. The database was used to train and test the developed ANN. Moreover, parallel to the experimental works, a three dimensional nonlinear finite element (FE) model using ABAQUS software was developed to predict the behaviour of SCC elliptical tube columns. The proposed ABAQUS model was verified against the current experimental results. The experimental results indicated that the failure modes of the SCC filled elliptical steel tube columns having large slenderness ratios were dominated by global buckling. Moreover, the composite columns possessed higher critical axial compressive capacities compared with their hollow section companions due to the composite interaction. However, due to the large slenderness ratio of the test specimens, the change of compressive strength of concrete core did not show significant effect on the critical axial compressive capacity of concrete filled columns although the axial compressive capacity increased with the concrete grade increase. The comparisons between the axial compressive load capacities obtained from experimental study and those predicted using simple methods provided in Eurocode 4 for concrete-filled steel rectangular tube columns showed a reasonable agreement. The proposed three dimensional FE model accurately predicted the failure modes, the load capacity and the load-deflection response of the columns tested. The experimental results, analysis and comparisons presented in this thesis clearly support the application of self-compacting concrete filled elliptical steel tube columns in construction engineering practice.