Abstract : Circular reinforced concrete (RC) members are often used in civil engineering structures, for instance, as piers and piles in bridge substructures. Also, their applications are frequently utilized as a fender and piling system for harsh water front and marine environments. Such members are usually reinforced with conventional steel bars and stirrups. Corrosion of steel reinforcement constitutes one of the major problems that shorten the lifetime serviceability and, hence, brittle failure of many concrete structures worldwide. In the last decade, the use of fiber reinforced polymer (FRP) materials has been growing to solve some of these problems and increase the anticipated service life of RC structures, such as bridges, parking garages, tunnels, and marine structures. Recently, the use of FRP bars in soft-eyes, which are openings in retaining walls that will be pierced by tunnel boring machines (TBMs), is gaining popularity in the field of tunnel excavation. In recent years, the shear behavior of RC members reinforced with FRP bars has been the focus of many studies. Accordingly, several codes and design guidelines are available for the design of concrete structures reinforced with FRP bars under shear loads. These codes and design guidelines were developed based on experimental work on rectangular concrete members reinforced with FRP bars and stirrups. Yet, no research seems to have assessed circular concrete members reinforced with FRP bars and spirals under shear loads. In this research study, an experimental program was designed to investigate the shear behavior of circular members reinforced with glass FRP (GFRP) and carbon FRP (CFRP) bars, and spirals. A total of twenty full-scale circular RC specimens, with a total length 3,000 mm and 500 mm in diameter, were fabricated and tested experimentally under shear load. The specimens were divided to five series; series I contains two reference steel-RC specimens with and without spiral reinforcement. Series II contains three specimens internally reinforced with GFRP longitudinal bars and without spiral reinforcement. Series III contains five specimens reinforced with GFRP longitudinal bars and spirals (Type I). Series IV includes six specimens reinforced with GFRP bars and spirals (Type II), while series V includes four specimens totally reinforced with CFRP reinforcement. The experimental tests were performed at the structural laboratory, Faculty of Engineering, University of Sherbrooke. The main objective of testing these specimens is to investigate the behavior of circular concrete members reinforced with GFRP or CFRP longitudinal bars and transverse spirals reinforcement. Several parameters have been studied; type of reinforcement, longitudinal reinforcement ratio, shear reinforcement ratio (spiral diameter and spacing), and shear-span-to-depth ratio. The test results of the tested specimens were presented and discussed in terms of load deflection response, crack patterns and modes of failure, ultimate shear capacities, concrete, longitudinal, and spiral strains, effectiveness of FRP spirals, and beam action versus arch action through four journal papers in this dissertation. In addition, an analytical investigation was conducted to evaluate the validity and accuracy of available FRP shear design equations in codes and design guidelines, and to determine whether certain modifications should be introduced in order to make them suitable for circular concrete members reinforced with FRP bars and spirals. The tested specimens were also analysed using Response 2000 (R2K), which is based on the modified compression field theory (MCFT). Based on the finding of this investigation, the shear capacity of FRP-RC members with circular sections may be determined with the approaches developed for rectangular sections provided that certain modifications are made to take into account the effective shear depth, equivalent breadth, the mechanical properties and geometry of GFRP or CFRP spirals. Furthermore, a new equation was introduced to quantify the spirals contribution (V[subscript s[florin]]) in circular concrete members to account for FRP spiral inclination, curvature, and strength reduction as a result of the stretching process. The proposed equation provided more reasonably accurate predictions. / Résumé : Les éléments circulaires en béton armé sont largement utilisés dans les structures en génie civil, comme par exemple, les pieux et les piles de pont. Également, ils sont très utilisés dans les systèmes de pieux battus dans des environnements agressifs et marines. Ces éléments sont habituellement utilisés avec un renforcement interne en acier. La corrosion de l'acier est un des problèmes majeurs qui diminuent la durée de vie et peuvent même amener la structure à la ruine et ce, partout dans le monde. Dans la dernière décennie, utiliser des polymères renforcés de fibres (PRF) est une bonne solution aux problèmes précédents et augmente la durée de vie des structures en béton armé, comme les ponts, les stationnements, les tunnels et les structures marines. Récemment, l'utilisation des barres de PRF dans les murs-diaphragmes, qui sont des ouvertures dans les murs de soutènement percé avec de la machinerie d'excavation de tunnel, gagne en popularité dans le domaine de l'excavation de tunnel. Depuis quelques années, le comportement en cisaillement des éléments en béton armé de PRF a été étudié dans plusieurs recherches. Par conséquent, les normes et les guides de dimensionnement sont disponibles pour les efforts tranchants. Ils sont développés à partir des expériences en laboratoires sur des éléments rectangulaires. Par contre, aucune recherche a été fait sur les éléments circulaires renforcés de PRF avec des barres et des spirales sous un effort tranchant. Dans ce sujet d'étude, un programme expérimental a été développé pour regarder le comportement en cisaillement des éléments circulaires en béton armé de PRV de verre (PRFV) et de PRF de carbone (PRFC), pour les barres longitudinales ainsi que pour les spirales (transversales). Un total de 20 spécimens circulaire de grandeur réelle, avec comme dimension 3,000 mm de long et 500 mm de diamètre, ont été fabriqués et testés à l'effort tranchant. Les spécimens ont été divisés en cinq séries; la série I contient deux spécimens de références en acier avec et sans renforcement transversal. La série II contient trois spécimens ayant de l'armature longitudinale en PRFV avec et sans renforcement transversal. La série III contient cinq spécimens renforcés de PRFV (Type I) dans le sens longitudinal et transversal. La série IV comprend six spécimens renforcés de PRFV (Type II) dans le sens longitudinal et transversal. Finalement, la série V comprend quatre spécimens totalement renforcés de PRFC. Les essais expérimentaux ont été réalisés dans le laboratoire de structure de la Faculté de génie à l'Université de Sherbrooke. L'objectif principal est de tester ces spécimens pour étudier le comportement des poutres circulaires en béton armé avec des PRFV et PRFC pour le renforcement longitudinal et transversal (spiral). Plusieurs paramètres y sont étudiés : type de renforcement, le taux d'armature longitudinal, le taux d'armature en cisaillement (diamètre et espacement des spires) ainsi que le rapport portée en cisaillement sur la profondeur effective. Les résultats sur les spécimens sont présentés et discutés en terme de la flèche, du réseau de fissuration, du mode de rupture, de la capacité ultime en cisaillement, le béton, la déformation longitudinale et transversale, efficacité des spirales en PRF, l'action de poutre à arche sur quatre articles de journal discutés dans cette dissertation, une étude analytique pour évaluer la validité des équations disponibles dans les codes et les guides de dimensionnement et de déterminer si certaines modifications devraient être faites pour que les sections circulaires avec un renforcement complet avec des spirales en PRF soient mieux adaptées. Les poutres testées ont également été analysées en utilisant Response 2000 (R2K), où il est basé sur la théorie du champ de compression modifiée (TCCM). Basé sur les résultats obtenus, la capacité en cisaillement des éléments circulaires en béton armé de PRF a été déterminé avec l'approche d'une section rectangulaire mais en changeant certains paramètres pour prendre en compte la profondeur effective, la largeur équivalente, des propriétés mécaniques ainsi que la géométrie des PRFV et PRFC pour les spirales. De plus, une nouvelle équation est introduite pour quantifier la contribution des spirales (V[indice inférieur s[florin]]) des éléments circulaires pour prendre en considération l'inclinaison des spires, de la courbure et de la réduction de la résistance suite à l'étirement de la spirale. L'équation proposée permet de prédire raisonnablement la capacité en cisaillement.

The purpose of this dissertation was to study factors affecting moisture distribution in 290-kilogram stirred-curd Cheddar cheese blocks cooled in stainless steel hoops. Uneven moisture distribution within blocks may create cheese with variable texture and flavor, which can be extremely costly to the producer. The effects of temperature, pH, and vacuum treatment on moisture distribution were investigated. Temperature, pH, moisture, and pressure profiles were presented. Also, comparisons were made between temperature profiles of 290- kilogram stirred-curd Cheddar cheese blocks cooled in stainless steel and in plywood hoops, as well as between temperature profiles of 66-kilogram Swiss cheese blocks cooled in cardboard and in plastic boxes. Moisture transferred from high to low temperature in the cheese blocks. Moisture may have transferred in response to thermally induced curd moisture-holding capacity gradients in the cheese blocks. Moisture also may have transferred in the cheese blocks by a mechanism similar to thermo-osmosis of liquids in porous solids. The cheese in the plywood or cardboard insulating materials cooled more uniformly than the cheese in the stainless steel or plastic containers. More uniform cooling of the cheese produced more uniform moisture distribution in the cheese blocks. Recommendations were made to help the cheesemaker produce cheese with even moisture distribution.

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Thesis (PhD (Mathematical Sciences. Applied Mathematics))--University of Stellenbosch, 2008. / This dissertation contains a detailed report on the results of a research project on the behaviour of a dynamical system consisting of a hoop to which a heavy particle is fixed at the rim. This loaded hoop rolls on a rough surface while remaining in the vertical plane. The motion of the hoop consists of various, possibly alternating, phases consisting of rolling without slipping, spinning or skidding motion and in some cases ends by hopping off the surface. A general mathematical model is developed, consisting of a system of second order ordinary differential equations, one for each of the three degrees of freedom. Analytic solutions are obtained in some cases; otherwise numerical solutions are used. Three specific applications of the general model are dealt with. In the first application the problem of massless hoops is investigated. The main emphasis is on the somewhat controversial question of what happens after the normal reaction becomes zero in a position where the particle is still moving downwards. A new result shows that the hoop can continue to move horizontally in a motion defined as skimming. The second application deals with rigid hoops and a large number of detailed results are presented. Classification schemes for the different types of behaviour are introduced and summarised in the form of phase diagrams. Some emphasis is placed on the rather amazing number of different patterns of motion that can be obtained by varying the parameters. In the third application two elastic models are analysed, with the primary purpose of explaining one aspect of the reported behaviour of experimental hoops, namely hopping while the particle is moving downwards. A chapter on experimental models rounds off the project.