Performance of bridges during previous earthquakes has demonstrated that many structural failures could be attributed to seismic deficiencies in bridge columns. Lack of transverse reinforcement and inadequate splicing of longitudinal reinforcement in potential plastic hinge regions of columns constitute primary reasons for their poor performance. A number of column retrofit techniques have been developed and tested in the past. These techniques include steel jacketing, reinforced concrete jacketing and use of transverse prestressing (RetroBelt) for concrete confinement, shear strengthening and splice clamping. A new retrofit technique, involving fibre reinforced polymer (FRP) jacketing has emerged as a convenient and structurally sound alternative with improved durability. The new technique, although received acceptance in the construction industry, needs to be fully developed as a viable seismic retrofit methodology, supported by reliable design and construction procedures. The successful application of externally applied FRP jackets to existing columns, coupled with deteriorating bridge infrastructure, raised the possibility of using FRP reinforcement for new construction. Stay-in-place formwork, in the form of FRP tubes are being researched for its feasibility. The FRP stay-in-place tubes offer ease in construction, convenient formwork, and when left in place, the protection of concrete against environmental effects, including the protection of steel reinforcement against corrosion, while also serving as column transverse reinforcement. Combined experimental and analytical research was conducted in the current project to i) improve the performance of FRP column jacketing for existing bridge columns, and ii) to develop FRP stay-in-place formwork for new bridge columns. The experimental phase consisted of design, construction and testing of 7 full-scale reinforced concrete bridge columns under simulated seismic loading. The columns represented both existing seismically deficient bridge columns, and new columns in stay-in-place formwork. The existing columns were deficient in either shear, or flexure, where the flexural deficiencies stemmed from lack of concrete confinement and/or use of inadequately spliced longitudinal reinforcement. The test parameters included cross-sectional shape (circular or square), reinforcement splicing, column shear span for flexure and shear-dominant behaviour, FRP jacket thickness, as well as use of FRP tubes as stay-in-place formwork, with or without internally embedded FRP crossties. The columns were subjected to a constant axial compression and incrementally increasing inelastic deformation reversals. The results, presented and discussed in this thesis, indicate that the FRP retrofit methodology provides significant confinement to circular and square columns, improving column ductility substantially. The FRP jack also improved diagonal tension capacity of columns, changing brittle shear-dominant column behavior to ductile flexure dominant response. The jackets, when the transverse strains are controlled, are able to improve performance of inadequately spliced circular columns, while remain somewhat ineffective in improving the performance of spliced square columns. FRP stay-in-place formwork provides excellent ductility to circular and square columns in new concrete columns, offering tremendous potential for use in practice. The analytical phase of the project demonstrates that the current analytical techniques for column analysis can be used for columns with external FRP reinforcement, provided that appropriate material models are used for confined concrete, FRP composites and reinforcement steel. Plastic analysis for flexure, starting with sectional moment-curvature analysis and continuing into member analysis incorporating the formation of plastic hinging, provide excellent predictions of inelastic force-deformation envelopes of recorded hysteretic behaviour. A displacement based design procedure adapted to FRP jacketed columns, as well as columns in FRP stay-in-place formwork provide a reliable design procedure for both retrofitting existing columns and designing new FRP reinforced concrete columns.

Dans les supraconducteurs de type II, le champ magnétique pénètre le matériau sous forme de vortex, tourbillon de courants supraconducteurs circulant autour d'un c¿ur normal. Dans les travaux de cette thèse, nous montrons comment le confinement d'un système à une échelle comparable à la longueur de cohérence ? nanométrique modifie sensiblement ses propriétés supraconductrices.Cette étude est menée dans des nanostructures de plomb déposé in-situ sur un substrat de silicium (111), puis mesurées par spectroscopie à effet tunnel, sous UHV, à 300 mK et sous champ magnétique.En confinement extrême (taille latérale D<<10 ?), le système créé des vortex Géants, objets quantiques prédits théoriquement depuis 45 ans. En confinement plus faible (D~10 ?), les vortex peuvent être piégés, s'organisent ensuite en réseau triangulaire d'Abrikosov, puis s'interpénètrent avec le champ magnétique croissant.Les îlots de Pb cristallins supraconducteurs sont reliés entre eux par une monocouche de mouillage de Pb, ici désordonnée et non supraconductrice. Au voisinage des îlots, cette couche acquiert des caractéristiques spectroscopiques spécifiques qui reflètent la supraconductivité induite par proximité et les interactions entre électrons de type Altshuler-Aronov. L'évolution spatiale des spectres tunnel sont simulés en combinant les équations d'Usadel et la théorie du blocage de Coulomb dynamique.En réduisant la distance entre les îlots, l'effet de proximité autour de chacun se recouvre, ce qui forme une jonction Josephson. Sont étudiés finement le nombre, la position, le spectre et la forme des c¿urs de vortex Josephson sous champ magnétique, à travers une grande panoplie de jonctions. / In type II superconductors, the applied magnetic field penetrates the material in quanta of flux called vortices, vortices of superconducting currents circulating around a normal core. In the work of this thesis, we show how the confinement of a system to a scale comparable to the nanometric coherent length ? substantially modifies its superconducting properties.This study is carried out in nanostructures of lead deposited in-situ on a silicon (111) substrate, then studied by scanning tunneling spectroscopy, under UHV, at 300 mK, and under magnetic field. In extremely confinement (lateral size D<<10 ?), systems create Giant vortices, quantum objects predicted 45 years ago. In the weakly confinement (D~10 ?), vortices may be pinned, then are organized in the triangular Abrikosov lattice, finally interpenetrate in surface superconductivity with the increasing magnetic field. Crystalline superconducting Pb islands are here connected by a disordered non-superconducting wetting layer of Pb. In the vicinity of each superconducting island, the wetting layer acquires specific tunnelling characteristics which reflect the interplay between the proximity induced superconductivity and the inherent electron correlations of this ultimate diffusive two-dimensional metal. Spatial evolution of the tunnel spectra are simulated by combining the Usadel equations and the theory of dynamic Coulomb blockade. With reducing the distance between the islands, the proximity effect around each overlaps and forms a Josephson junction. Thanks to the tunneling spectroscopy, number, position, the spectrum and the form of Josephson vortex cores are studied in detail for a large variety of junctions.

Les résultats décrits dans cette thèse démontrent une relation complexe entre le confinement géométrique de molécules à 2D et les propriétés de chiralité. Il a été démontré qu’une chiralité multimodale peut être observée pour des systèmes non chiraux par le biais du confinement 2D. Les molécules H5T forment, sur Au(111), des domaines pour lesquels deux types de chiralité peuvent être observés. Les études sur le système H5T/Au(111) ont prouvé que des interactions simples, de type van der Waals sont susceptibles de créer des chiralités complexes, ce qui donne un caractère générique a ce type de phénomène. Une autre question importante est l’apparition, pour les molécules C-12, des domaines chiraux induits par des interactions intermoléculaires spécifiques: les liaisons hydrogène entre les groupements azobenzènes de molécules voisines. L’orientation des deux domaines chiraux est déterminée par l’orientation de l’un des deux dimères d’azobenzène stable par rapport à l’Au(111).La seconde partie de la thèse est dédiée à l’étude de l’influence du confinement 3D sur la chiralité de gouttes de cristal liquide cholestérique (CLC). Grâce à la nature photo-sensible du dopant chiral utilisé, nous avons été capables de modifier le pas choléstérique du mélange de CLC et par conséquent de déterminer l’expression de la chiralité pour un ratio rayon/pas choléstérique variable. Nous sommes parvenus à contrôler le pas choléstérique au sein de gouttes par irradiation UV et nous avons étudié les variations structurelles que l’irradiation induite. Nous avons observé que le confinement 3D d’un mélange de CLC photo-sensible a une influence positive sur l’inversion de l’hélice dans la goutte. / The first part of the thesis is devoted to studies of the self-assembled monolayers of discotic liquid crystals by the STM measurements at the liquid/solid interface. For the case of a model H5T molecule the self-assembled monolayers have evidenced both: point and organizational types of chirality, despite of the fact that neither the molecule nor the substrate was chiral. For another molecular system, C-12 - a triphenylene peripherally substituted with azobenzene moieties, self-assemblies bearing the chiral nature were also evidenced. Chirality was induced by formation of six dimers of azobenzene subunits coming from the neighboring molecules, which formed “rosettes” of clockwise or counter-clockwise rotation. For the H5T, the chirality was mediated by classical van der Waals interactions between molecules and between molecules and substrate. In the case of C-12 it was shown that the self-assembly originates from the substrate-mediated hydrogen bonding between the azobenzene moieties of neighboring molecules. The second part of the thesis presents studies of the influence of the 3D confinement on the chirality of the photoactive cholesteric liquid crystal (CLC) droplets. Due to the photo-responsive character of a chiral dopant we were able to modify the cholesteric pitch of the CLC mixture and thus to map the expression of chirality for a varying geometrical confinement parameter: radius-to-pitch. We evidenced a successful control of the droplets structure by UV irradiation and we studied the induced structural changes. In particular, the 3D confinement of a photo-responsive CLC mixture was shown to positively support the helix inversion within the cholesteric droplets.

L’effet du confinement de la phase amorphe lors de la cristallisation du poly(éthylène téréphtalate) et du poly(acide lactique) a été étudié à multi-échelles. Ces polymères peuvent exister sous forme amorphe et semi-cristalline. La relation entre la microstructure et les propriétés viscoélastiques des matériaux a été mise en évidence par les expériences en diffusion des rayons X aux petits angles (SAXS) et aux grands angles (WAXS), en Calorimétrie différentielle à balayage (DSC), en traction, en analyseur mécanique dynamique (DMA) et en nanoindentation. La différence de la structure moléculaire du PET et du PLA est essentielle pour leur comportement physique et mécanique. Au cours de la cristallisation, une autre phase amorphe dont le comportement mécanique est plus rigide que la phase amorphe traditionnelle a été formée. La DSC permet de quantifier la dépendance de la fraction de cette phase amorphe rigide en fonction du taux de cristallinité. La technique de diffusion des rayons X permet d’étudier l’évolution de la microstructure (dimension de cristallites, épaisseur des phases) lors de la cristallisation. Le comportement mécanique des polymères a été étudié à différentes échelles. Les essais de DMA permettent non seulement d’étudier le comportement viscoélastique macroscopique des polymères mais aussi de quantifier les propriétés viscoélastiques de chaque phase amorphe via leur température de transition vitreuse. Cela a été utilisé comme données d’entrée dans des modèles micromécaniques. La nanoindentation permet de mesurer les propriétés mécaniques du matériau à son extrême surface. Dans la dernière partie, une approche des propriétés mécaniques macroscopiques des matériaux a été réalisée par des modèles micromécaniques d’homogénéisation en se basant sur la morphologie matrice-inclusion. / The signature of confinement effect onto the mechanical properties of the amorphous phase during crystallization of two polymers, Polyethylene terephthalate (PET) and poly(lactic acid) (PLA) was investigated at multi-scale. The two polymers have the advantage of being either in bulk amorphous or in semi-crystalline state. The relation between the microstructure and the viscoelastic properties of materials is put light on by the experiments of X-Ray Scattering, differential scanning calorimetry (DSC), by tensile strength tests, by dynamic mechanical analysis (DMA) and by nanoindentation. The difference in molecular structure of PET and PLA is essential for their physical and mechanical behavior. During crystallization, the second amorphous phase whose mechanical behavior is more rigid than conventional amorphous phase was formed. DSC is used to quantify the rigid amorphous fraction dependence on the crystallinity. The technique of X-ray scattering is used to study the evolution of the microstructure (crystallite size, lamella thickness) during crystallization. The mechanical behavior of materials was studied at different scale. DMA tests allow not only to study the macroscopic behavior of viscoelastic polymers but also to quantify the viscoelastic properties of each amorphous phase through their glass transition temperature. This was used as input data in micromechanical models. Nanoindentation is used to measure the mechanical properties of the materials at the extreme surface. In the last part, the homogenization micromechanical modeling was performed based on the matrix - inclusion morphology in order to predict the macroscopic mechanical behavior laws of materials.

Orientadores: Irenilza de Alencar Nääs, Daniella Jorge de Moura / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-08T00:21:53Z (GMT). No. of bitstreams: 1 Souza_SilviaReginaLucasde_D.pdf: 2823600 bytes, checksum: 559235ef57bb2a95048ac80bb33c0165 (MD5) Previous issue date: 2006 / Resumo: A tendência atual é que o segmento de produção de leite se torne uma atividade mais precisa e economicamente viável. Sabe-se que as diferenças do microclima promovem mudanças no comportamento animal, entretanto, as medidas convencionais, da forma como foram feitas hoje, são evasivas, podendo levar a eventuais erros na interpretação dos resultados. O presente experimento foi realizado em uma fazenda comercial em São Pedro- SP, onde vacas leiteiras são monitoradas através de seis microcâmeras coloridas com 420 linhas de resolução e lente de 120 graus para avaliar seu comportamento. Foram realizadas observações visuais indiretas paralelas às análises do software e também observações visuais indiretas instantâneas para analisar o comportamento. O galpão foi dividido em 18 quadrantes para o mapeamento das distribuições climáticas e os dados foram processados no programa computacional Surfer® 6.0 para analisar a sua homogeneidade. O objetivo principal deste trabalho foi o desenvolvimento de uma metodologia de avaliação comportamental de vacas leiteiras confinadas, em função do microclima de alojamento em galpão de freestall, utilizando análise de imagens. Os resultados obtidos da análise multivariada com os dados das observações visuais instantâneas, apontaram no gráfico de Componentes Principais, os comportamentos considerados importantes, por se obterem respostas visualmente expressivas quando afetadas pelo ambiente de alojamento, tais como; bebendo água, comendo e deitadas na cama. As distribuições climáticas dentro do galpão não foram homogêneas, quando os equipamentos de climatização não estavam ligados. Fez-se correlação com as preferências térmicas apresentados pelos animais através dos gráficos de Componentes Principais e Índice de Temperatura e Umidade (ITU) das visualizações indiretas instantâneas, espaçadas e através da visão computacional. Concluiu-se que a metodologia de visão computacional desenvolvida para avaliação comportamental, apresentou algumas limitações, onde necessitam-se de ajustes nos algoritmos / Abstract: The current tendency of the milk production sector is to become more precise and economically feasible. It is known that differences in microclimate cause changes in animal behavior; however, conventional measures taken nowadays are evasive and can produce misinterpretation of the results. The current experiment was carried out in a commercial farm in São Pedro- SP, where milking cows were monitored using a total of six color micro-cameras with spatial resolution of 420 horizontal lines and 120 degrees lenses for behavior analysis. Indirect visual observations were performed parallel to the software analysis, as well as instantaneous indirect visual observations. The barn was divided into 18 quadrants in order to perform the climatic distribution mapping. The data gathered were processed using the software Surfer ® 6.0 to check for homogeneity. The primarily objective of this work was the development a milking cow?s behavior evaluation methodology as a function of freestall housing micro-climate, using image analysis. The results obtained through the multivariate analysis of the data from instantaneous observations pointed through the graphic of main components, the behaviors considered important for obtaining visually expressive responses when affected by the housing environment, such as: drinking water, feeding and laying down. The climatic distributions within the barn were not homogeneous when the cooling systems were not on. Correlations with the preset thermal values presented by the animals through the main component charts and THI from indirect visual instantaneous observations were performed and was concluded that the methodology for computational vision has been developed with few limitations and pending adjustments on its algorithms / Doutorado / Construções Rurais e Ambiencia / Doutor em Engenharia Agrícola

The Ottawa-Carleton Detention Centre (OCDC) is notorious for its austere conditions of confinement and human rights violations. In response to widespread criticism, the Ontario provincial government created a dedicated task force in 2016 to address longstanding issues at the jail. To date, little research has examined how OCDC has maintained these deplorable conditions of confinement despite concerted effort to improve them. Drawing on Mathiesen’s (1990) neutralization techniques, this thesis reveals the tactics used by government officials and jail functionaries to maintain the status quo at OCDC and stifle transformative change by comparing task force recommendations with their ensuing implementation. Through a qualitative content analysis of the OCDC task force progress reports, trend analyses, Ombudsman, Community Advisory Board, Independent Review of Corrections, and Jail Accountability & Information Line reports documenting issues at OCDC, I demonstrate how the Ontario provincial government and OCDC administration (a) refer to competing demands, higher authority, policy and procedure, or safety and security as excuses for not instituting changes, (b) define policy alternatives as irrelevant or impossible to implement, (c) postpone implementation of measures for not being developed enough or possible now, as well as (d) puncture and (e) absorb policy alternatives to uphold the status quo and impede transformative change. In doing so, I expose the provincial penal system’s proclivity to ‘finish’ (Mathiesen, 1974) alternatives that threaten the current system, thereby gutting new ideas of their ability to generate meaningful social change. The insights provided by this thesis help lay the groundwork for future critical criminological research to examine the barriers to social change in the penal field on a sub-national, national, and international scale.

Catalytic conversion of methanol to hydrocarbons (MTH) provides an alternative route to the production of fuels and important industrial chemicals that are currently mainly produced from the refinery of petroleum. The ability to control the product distribution of MTH according to the demands of specific applications is of crucial importance, which relies on the thorough understanding of the reaction pathways and mechanisms. Despite the significant research efforts devoted to zeolite-catalyzed MTH, it remains a challenge to establish a firm correlation between the physicochemical properties of zeolites and their catalytic activity and selectivity. In this dissertation, we designed a series of experiments to gain fundamental understanding of how the structural and compositional parameters of zeolites influence their catalytic performances in MTH. We investigated different types of zeolites, covering large-pore Beta, medium-pore ZSM-5, and small-pore DDR zeolites, and tune their crystallite size/diffusion length, hierarchical (mesoporous) structure, and Si/Al ratio (density of acid sites) by controlled synthesis or post-synthesis treatments. The influence of mesoporosity of a zeolite catalyst on its catalytic performance for MTH, with zeolite Beta, was first investigated. The shorter diffusion length associated with the hierarchical structure results in a lower ethylene selectivity but higher selectivity towards C4-C7 aliphatics. Then we investigated the correlation between the Al content and the ethylene selectivity by ZSM-5 zeolites with similar crystal sizes but varied Si/Al ratios. We realized that ethylene selectivity is promoted with the increase of aluminum content in the framework. These two observations can be explained by the same mechanistic reason: the ethylene selectivity is associated with the propagation degree of the aromatics catalytic cycle and essentially determined by the number of the acid sites that methylbenzenes would encounter before they exit the zeolite crystallite. Last we explored how to maximize the propylene selectivity by tuning the physicochemical properties of DDR zeolites. Due to the confined pore space in DDR, the propagation of olefins-based catalytic cycle can be preferentially promoted in a tunable manner, which cannot be realized with zeolites having larger pores. Thus, the propylene selectivity increases with increasing the Si/Al ratio and decreasing the crystallite size.

Zeolites are crystalline microporous solid acids composed of silica-rich frameworks with aliovalent Al heteroatoms substituted in crystallographically-distinct location sand arrangements, which generate anionic lattice charges that can be compensated by protons and extra framework metal cations or complexes that behave as catalytic active sites. Protons that charge-compensate Al are similar in Brønsted acid strength, yet differ in reactivity because their bound intermediates and transition states are stabilized by van der Waals interactions with confining microporous cavities, and by electrostatic interactions with proximal heteroatoms and adjacent protons. A diverse array of framework Al and extra framework H⁺site ensembles are ubiquitous in low-silica and low-symmetry zeolite frameworks (e.g., MFI, MOR), which cause measured turnover rates to reflect the reactivity-weighted average of contributions from each distinct site ensemble. The reactivity of distinct sites can be further masked by diffusion barriers often imparted by microporous domains and secondary reactions of primary products, which become increasingly prevalent as products encounter higher numbers of active sites during diffusion prior to egress from zeolite crystallites. Consequently,catalytic behavior often depends on zeolite material properties at orders-of-magnitude different length scales, which depend on the specific protocols used in their synthesis and crystallization.<div><br></div><div><div>In this work, CHA zeolites that contain only one symmetrically-distinct lattice site for Al substitution are used as model materials to decouple the effects of proton</div><div>location and proximity in vibrational spectra and turnover rates for acid catalysis. Interactions between proximal protons influence their equilibrium distribution among anionic lattice O atoms in AlO⁻_4/2tetrahedra, and result in temperature-dependent changes to vibrational frequencies and intensities of the asymmetric OH stretching region in infrared spectra measured experimentally and computed by density functional theory (DFT). Protolytic propane cracking and dehydrogenation, a catalytic probe reaction of the intrinsic reactivity of Brønsted acid protons, occur with turnover rates (748 K, per H⁺) that are an order-of-magnitude higher on paired protons than isolated protons, resulting from entropic benefits provided to late carbonium ion-pair transition states by proximal protons. These results indicate that cationic transition states can be stabilized entropically through multi-ion interactions with lattice anion and cation sites. Precise interpretation and quantification of the reactivity of different types and ensembles of Brønsted acid protons in zeolites requires that protolytic chemistry prevails in the absence of secondary active sites or other kinetically-relevant processes, a requirement generally met for alkane cracking but not dehydrogenation on H-form zeolites. Propane dehydrogenation activation energies vary widely (by >100 kJ mol⁻¹) among H-form zeolites of different structure (MFI, MOR, CHA) and composition (Si/Al = 10 – 140) because reactant-derived carbonaceous deposits form in situ and catalyze alkane dehydrogenation under non-oxidative conditions through hydride transfer pathways. Contributions of reactant-derived active sites to propane dehydrogenation rates are quantified through a series of transient and steady-state kinetic experiments with co-fed alkene and dihydrogen products, and are found to depend on gradients in product pressures that are present in integral reactors under non-ideal plug-flow hydrodynamics. Propane dehydrogenation rates collected at initial time-on-stream and in the presence of co-fed H₂ solely reflect protolytic reaction events and can be used to interpret differences in the reactivity of distinct proton sites and ensembles for alkane activation catalysis. The reaction conditions identified here can be used to remove or suppress the reactivity of carbonaceous active sites during catalysis, or to engineer the formation of organocatalysts on zeolite surfaces for selective dehydrogenation or hydride transfer reactions.</div></div><div><br></div><div><div>Synthetic strategies to decouple bulk and active site properties at disparate length scales, which are typically correlated in MFI zeolites crystallized hydrothermally, are developed by adding a second heteroatom and organic structure directing agent (SDA) to synthesis media. Crystallite size and morphology are independently varied from Al content by incorporating B heteroatoms into zeolitic frameworks, which generate protons that are catalytically irrelevant compared to those compensating Al, and NH₃ temperature-programmed desorption methods are developed to differentiate between these two types of proton sites. The siting of Al heteroatoms in distinct locations and ensembles is influenced by the decrease in cationic charge density among occluded SDAs, in cases where ethylenediamine is co-occluded with tetra-<i>n</i>-propylammonium cations. The co-occlusion of organic SDAs enables crystallizing MFI zeolites with different bulk properties but similar Al distributions, or with similar bulk properties and different Al distributions. MFI zeolites crystallized with these methods provide model materials that can be interrogated to decouple the effects of bulk and atomicscale properties on acid catalysis, and open opportunities to exploit these material properties by designing active site ensembles and crystallite diffusion properties for catalytic chemistries that depend on coupled reaction-transport phenomena.</div></div>

This thesis summarizes our latest findings on liquid-solid equilibria for fluids in confined spaces. In the first part of the thesis we introduce a microscopic lattice model which we have developed for the exploration of the freezing and melting phenomena in mesoporous solids with arbitrary geometries of the pore spaces. By applying this model to materials with well-ordered pore structures we (i) establish the mechanisms of the freezing and melting transitions and identify the equilibrium and metastable transition branches for different boundary conditions, (ii) illuminate the role of thermodynamic fluctuations, and (iii) find rigorous equations governing the transition temperatures for the lattice model considered. In the second part of the thesis the results obtained with the ordered pore systems are used for an in-depth analysis of the transitions occurring in geometrically disordered porous solids. First, by considering the ink-bottle pore geometry the efficacies of the different phase transition mechanisms established in the first part are elucidated. As a particularly important result, it is shown that thermodynamic fluctuations may alter the transition mechanisms. In the light of these findings the freezing and melting behaviors in statistically disordered porous materials are discussed. In the third part of the thesis several experimentally-relevant topics are considered and the potentials of the microscopic model for evaluation of the experimental data are demonstrated.

When compared to traditional concrete, steel fibre reinforced concrete (SFRC) shows several enhancements in performance, including improved tensile resistance, toughness and ductility. One potential application for SFRC is in columns where the provision of steel fibres can improve performance under axial and lateral loads. The use of SFRC can also allow for partial replacement of transverse reinforcement required by modern seismic codes. To improve workability, self-consolidating concrete (SCC) can be combined with steel fibres, leading to highly workable SFRC suitable for structural applications. Recent advances in material science have also led to the development of ultra-high performance fibre reinforced concretes (UHPFRC), a material which exhibits very high compressive strength, enhanced post-cracking resistance and high damage tolerance. In heavily loaded ground-story columns, the use of UHPFRC can allow for reduced column sections. This thesis presents the results from a comprehensive research program conducted to study the axial behaviour of columns constructed with highly workable SFRC and UHPFRC. As part of the experimental program, twenty-three full-scale columns were tested under pure axial compressive loading. In the case of the SFRC columns, columns having rectangular section and constructed with SCC and steel fibres were tested, with variables including fibre content and spacing of transverse reinforcement. The results confirm that use of fibres results in improved column behaviour due to enhancements in core confinement and cover behaviour. Furthermore, the results demonstrate that the provision of steel fibres in columns can allow for partial replacement of transverse reinforcement required by modern codes. The analytical investigation indicates that confinement models proposed by other researchers for traditional RC and SFRC can predict the response of columns constructed with SCC and highly workable SFRC. In the case of the UHPFRC columns, variables included configuration and spacing of transverse reinforcement. The results demonstrate that the use of appropriate detailing in UHPFRC columns can result in suitable ductility. Furthermore, the results demonstrate the improved damage tolerance of UHPFRC when compared to traditional high-strength concrete. The analytical investigation demonstrates the need for development of confinement models specific for UHPFRC.