O objetivo deste trabalho foi estudar o efeito do confinamento em encontros de pilares de concreto com uma determinada resistência à compressão com lajes ou vigas de concreto de menor resistência. Com isso pretendeu-se desenvolver um melhor entendimento desse assunto, ainda pouco explorado, avaliar recomendações de algumas normas e, onde necessário e possível, sugerir uma solução alternativa. Foram ensaiados à compressão axial vinte e dois modelos reduzidos que representavam pilares de canto ou internos, incorporando parte da laje, e pilares isolados, cujos resultados foram comparados com recomendações de normas, ACI-318, CSA 23.3 e pesquisadores como, Gamble e Klinar, Ospina e Alexander, Bianchini e Silveira dos Santos. Na verdade, esta pesquisa é um prosseguimento daquela realizada por Silveira dos Santos. Complementando os estudos experimentais, modelos em elementos finitos possibilitaram a melhor compreensão desse efeito e ainda viabilizaram a comparação dos resultados experimentais com o critério de confinamento sugerido pelo CM CEB-FIP e pelo Eurocode EC2. Concluiu-se que apenas para pilares internos, cercados por laje em toda a volta, há um aumento de resistência do conjunto por efeito do confinamento do concreto da laje, devendo-se ainda respeitar certos limites. Para pilares de canto é necessária a utilização de algum elemento que compense a falta do concreto, como por exemplo, uma armadura transversal. / The goal of this paper is to study the effect of the confinement in connections of concrete columns having certain strength with lower strength concrete slabs or beams. It was intended to develop a better understanding of this subject, still little explored, to evaluate some code recommendations and, where necessary and possible, to suggest a alternative solution. Twenty-two specimens of reduced models were tested in compression representing corner or internal columns, incorporating part of the slabs, and isolated columns. These results were compared with recommendations of codes, ACI- 318, CSA 23,3 and researchers as, Gamble and Klinar, Ospina and Alexander, Bianchini and Silveira dos Santos. Indeed, this research is a continuation of that one carried through by Silveira dos Santos. Complementing the experimental studies, finite elements models made possible the best understanding of this effect and still they had made possible the comparison of the experimental results with the confinement criterion suggested for CM CEB-FIP and Eurocode EC2. It had concluded that only for internal columns, surrounded by slab, there is a strength increase of the specimen caused by confinement of the slab\'s concrete respecting certain limits. For corner columns it\'s necessary the utilization of some element that compensates the missing concrete, for example, a transversal reinforcement.

Typescript. / Digitized by Kansas Correctional Industries

O presente trabalho fornece uma visão geral sobre a aplicação, o dimensionamento e o detalhamento de pilares confeccionados com concreto de alto desempenho (CAD), cujo principal atributo analisado é a resistência do concreto à compressão. A ênfase do estudo é dada à aplicação do CAD em pilares de edifícios. São apresentadas as principais diferenças entre pilares de CAD e pilares confeccionados com concretos de baixa resistência (fck < 40 MPa), sendo abordados, com base em códigos vigentes e em resultados experimentais, os diagramas tensão-deformação mais indicados, as formas de consideração das não-linearidades física e geométrica, as excentricidades a serem consideradas no dimensionamento, as causas e a forma de prevenção do fenômeno da perda do cobrimento (característico de pilares de CAD), a importância e a forma de consideração do confinamento e algumas disposições construtivas necessárias para o bom desempenho do pilar. Procurou-se, sempre que possível, apresentar os aspectos que não necessitam de alterações, ou seja, que podem ser considerados da mesma forma para concretos de baixa e de alta resistência. Finaliza-se com a apresentação de alguns exemplos de dimensionamento de pilares de CAD, abordando os tópicos analisados ao longo do texto. / The present work provides an overview of use and design of columns made with high performance concrete (HPC), whose main analyzed attribute is the compression strength of the concrete. The emphasis of the study is given to the application of HPC in columns of buildings. The main differences are presented among columns of HPC and columns made with low strength concrete (fck < 40 MPa), being approached, on base in effective codes and in experimental results, the more suitable stress-strain diagrams, the forms of consideration of the physical and geometrical non-linearities, the eccentricities to be considered in the design, the causes and the form of prevention of the phenomenon of the spalling of the concrete cover (characteristic of HPC columns), the importance and the form of consideration of the confinement and some necessary constructive dispositions for the good performance of the column. It was sought, whenever possible, to present the aspects that don\'t need alterations, that is to say, that can be considered in the same way for low and high strength concretes. It concludes with the presentation of some examples of design of HPC columns, approaching the topics analyzed along the text.

Nowadays, industrial processes are having to be rapidly developed to meet high standards regarding increases in the production rate and/or improving product quality. Fulfilling these requirements is having to work in tandem with the pressure to reduce energy consumption due to global environmental regulations. Consequently, most industrial processes critically rely on automatic control, which can provide efficient solutions to meet such challenges and prerequisites. For this thesis, an intelligent system design has been investigated for controlling the distillation process, which is characterised by highly nonlinear and dynamic behaviour. These features raise very challenging tasks for control systems designers. Fuzzy logic and artificial neural networks (ANNs) are the main methods used in this study to design different controllers, namely: PI- PD- and PID-like fuzzy controllers, ANN-based NARMAL2 in addition to a conventional PID controller for comparison purposes. Genetic algorithm (GA) and particle swarm optimisation (PSO) have also been utilised to tune fuzzy controllers by finding the best set of scaling factors. Finally, an intelligent controller is proposed, called ANFIS-based NARMA-L2, which uses ANFIS as an approximation approach for identifying the underlying systems in a NARMA-L2 configuration. The controllers are applied to control two compositions of a binary distillation column, which has been modelled and simulated in MATLAB® and on the Simulink® platform. Comparative analysis has been undertaken to investigate the controllers' performance, which shows that PID-like FLC outperforms the other tested fuzzy control configurations, i.e. PI- and PD-like. Moreover, PSO has been found to outperform GA in finding the best set of scaling factors and over a shorter time period. Subsequently, the performance of PID-like FLC has been compared with ANN-based NARMA-L2 and the proposed ANFIS-based NARMA-L2, by subjecting the controlled column to different test scenarios. Furthermore, the stability and robustness of the controllers have been assessed by subjecting the controlled column to inputs variance and disturbances situations. The proposed ANFIS-based NARMAL2 controller outperforms and demonstrates more tolerance of disturbances than the other controllers. Finally, the study has involved investigating the control of a multicomponent distillation column due to its significant enhancement in operational efficiency regarding energy saving and recent widespread implementation. That is, Kaibel's distillation column with 4×4 configuration has been simulated also in MATLAB® and on the Simulink® platform with the proposed controller being implemented to control the temperatures of the column and the outcomes subsequently compared with conventional PID controllers. Again, the novel controller has proven its superiority regarding the disturbances tolerance as well as dealing with the high dynamics and nonlinear behaviour.

A mathematical model was developed to predict the exchange of one cation by another in a soil column undergoing one dimensional cation solution displacement under steady state flow conditions. The model allowed prediction of both the solution and exchanger phase concentration of the cation in question. The model consists of a material balance equation which is a parabolic type partial differential equation. The assumption was made that equilibrium was reached instantaneously between the cations in the solution phase and the exchanger phase. This assumption reduced the material balance equation to a form that allowed numerical solution providing the data concerning the cation exchange isotherm and the initial and boundary conditions are available. FORTRAN programs were written for the numerical computation of the problem involved. The computation was done on a digital computer. The model was verified by comparing the theoretically computed cation concentration profile with data from actual soil column experiments. The cation exchange of Mg→Ca was tested on Yolo fine sandy loam, Nibley clay loam and Haford Sandy loam columns. The exchange of Na→Ca was also tested on Yolo fine sandy loam. Satisfactory agreement between the column experiment values and the theoretically computed values was obtained.

Concrete filled steel tubular (CFST) columns are widely used in building and infrastructure projects throughout the world.Compared with other form of construction CFST columns offer superior structural performance and speed and ease of construction.Design procedures and recommendations provided in most of the design codes are often tedious and complex. There have been attempts to simplify the design procedure by providing a simplified expression to predict the capacity of a CFST under a general loading condition.In this thesis a rigorous analysis procedure was presented for the analysis of CFST beam-columns under general loading conditions.All the analytical results were verified by comparisons with the available test results and current ACI, AISC AND Eurocode 4 design codes. The comparisons demonstrated that the proposed numerical equations are accurate, and slightly conservative. Based on the numerical analysis, a simple and easy to follow calculation procedure was proposed for design of CFST columns under either uniaxial or biaxial bending moment and axial load. / Doctor of Philosophy (PhD)

PhD / Abstract: The objective of this research is to investigate the interaction of local and overall flexural buckling in cold-formed stainless steel columns. Literature study exposes a lack of understanding of this subject and a need for experimental data, particularly on the local-overall interaction buckling of stainless steel open sections. Two separate experimental programs were therefore carried out. The first program included 36 tests on pin-ended lipped channel columns. Three alloys were considered: AISI 304, AISI 430 and 3Cr12. The specimens were designed to fail by local-overall interaction buckling in the inelastic stress range, thus highlighting the non-linear behaviour of stainless steel. Half of the specimens were tested under a concentric load. The other half had the load applied with a nominal eccentricity of Le/1500. The test results demonstrate the imperfection sensitivity of local-overall interaction buckling and illustrate the shift in effective centroid in pin-ended columns with singly symmetric cross-section. The second experimental program studied local-overall interaction buckling in 24 pin-ended stainless steel I-section columns. The specimens consisted of plain channels connected back-to-back using sheet metal screws. Two alloys were considered: AISI 304 and AISI 404. Local and overall imperfections were carefully measured in both experimental programs. Extensive material testing was carried out on the alloys employed in the experimental program, in order to determine tensile and compressive material properties, anisotropic parameters and enhanced corner properties. A detailed finite element model is presented, which includes non-linear material behaviour, anisotropy, increased material properties of the corner areas and local and overall imperfections. The model was verified against the two aforementioned experimental programs and against additional data available in literature on stainless steel SHS columns. The model yielded excellent predictions of the specimen failure mode, ultimate strength and load-deformation behaviour. The finite element model was used to generate additional data for stainless steel columns with lipped channel, plain channel, SHS and I-shaped cross-section, failing by local-overall interaction buckling. The parametric studies covered the practical ranges of overall and cross-sectional slenderness values. The Australian/New Zealand, European and North American standards for stainless steel were evaluated using the available data. The comparison reveals an inability of the design codes to properly account for the interaction effect as the cross-sectional slenderness increases. Predictions are unsafe for I-section columns with intermediate or high cross-sectional slenderness. A direct strength method is proposed for stainless steel columns, accounting for the local-overall interaction effect. The method offers a simple design solution which fits within the framework of the current Australian and North-American standards.

Thesis (Ph. D.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 105-107). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This study examines differences between male and female as well as UK and US authors in newspaper text, specifically column writing. Many studies have shown that women have a tendency to show greater involvement in text by using personal and subjective reference. The present study applied corpus linguistic methods to 145 columns retrieved from two broadsheet newspapers, The Guardian and The New York Times. The usage of first person singular and plural pronouns was examined to determine whether there are gender-based or cultural differences in the way the authors show involvement in the texts. The data show no significant differences between male and female or UK and US authors. The uneven gender distribution of the sampling, conventions of journalism and column writing as well as women’s adaptation to the communication style of public sphere may be some of the reasons for the non-significant differences between the studied dimensions.